U.S. patent application number 17/277802 was filed with the patent office on 2021-10-14 for valve train assembly.
The applicant listed for this patent is Eaton Intelligent Power Limited. Invention is credited to Majo Cecur.
Application Number | 20210317760 17/277802 |
Document ID | / |
Family ID | 1000005695453 |
Filed Date | 2021-10-14 |
United States Patent
Application |
20210317760 |
Kind Code |
A1 |
Cecur; Majo |
October 14, 2021 |
VALVE TRAIN ASSEMBLY
Abstract
A cam phasing mechanism (1) for a cam assembly (100) of an
internal combustion engine, the cam assembly (100) comprising a
camshaft (120) and an actuator (130) for opening a valve (505) at a
reference position of rotation of the camshaft (120), the cam
phasing mechanism (1) comprising: a force transfer member (2a) for
interposition between the camshaft (120) and the actuator (130) of
the cam assembly (100) for transferring force between the camshaft
(120) and the actuator (130); and an adjuster (2b) for selectively
moving the force transfer member (2a) to adjust the reference
position of rotation of the camshaft (120).
Inventors: |
Cecur; Majo; (Turin,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eaton Intelligent Power Limited |
Dublin |
|
IE |
|
|
Family ID: |
1000005695453 |
Appl. No.: |
17/277802 |
Filed: |
September 19, 2019 |
PCT Filed: |
September 19, 2019 |
PCT NO: |
PCT/EP2019/075194 |
371 Date: |
March 19, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01L 1/267 20130101;
F01L 1/344 20130101; F01L 1/047 20130101; F01L 13/0063 20130101;
F01L 2305/00 20200501; F01L 1/146 20130101 |
International
Class: |
F01L 1/344 20060101
F01L001/344; F01L 1/047 20060101 F01L001/047 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 19, 2018 |
GB |
1815261.1 |
Claims
1. A cam phasing mechanism (1) for a cam assembly (100) of an
internal combustion engine, the cam assembly (100) comprising a
camshaft (120) and an actuator (130) for opening a valve (505) at a
reference position of rotation of the camshaft (120), the cam
phasing mechanism (1) comprising: a force transfer member (2a) for
interposition between the camshaft (120) and the actuator (130) of
the cam assembly (100) for transferring force between the camshaft
(120) and the actuator (130); and an adjuster (2b) for selectively
moving the force transfer member (2a) to adjust the reference
position of rotation of the camshaft (120).
2. The cam phasing mechanism (1) according to claim 1 , wherein the
adjuster (2b) comprises a first member (4) and a second member (5),
wherein the first member (4) is moveable relative to the second
member (5) for selectively moving the force transfer member (2a)
relative to the second member (5) to adjust the reference position
of rotation of the camshaft (110).
3. The cam phasing mechanism (1) according claim 2, wherein the
first member (4) is continuously moveable relative to the second
member (5) for continuously adjusting the reference position of
rotation of the camshaft (120) within a predetermined range.
4. The cam phasing mechanism (1) according to claim 2, wherein the
force transfer member (2a) is spaced from the first member (4) by a
third member (3).
5. The cam phasing mechanism (1) according to claim 4, wherein the
third member (3) is pivotable about the first member (4).
6. The cam phasing mechanism (1) according to claim 4, wherein the
third member (3) is Y-shaped such that a distal portion (33) of the
third member (3) is a bifurcated portion to enclose the force
transfer member (2a).
7. The cam phasing mechanism (1) according to claim 2, comprising a
driving member (10) for driving the second member (5) of the
adjuster (2b).
8. The cam phasing mechanism (1) according to claim 7, wherein an
axis of rotation of the driving member (10) is perpendicular to an
axis of rotation of the second member (5).
9. The cam phasing mechanism (1) according to claim 1, wherein the
first member (4) is moveable relative to the second member (5) by
translational motion of the first member (4).
10. The cam phasing mechanism (1) according to claim 1, wherein the
force transfer member (2a) comprises a first roller (21) for
engagement with the camshaft (120) of the cam assembly (100) and a
second roller (22) for engagement with the actuator (130) of the
cam assembly (100).
11. The cam phasing mechanism (1) according to claim 10, wherein
the first roller (21) and the second roller (22) are each
independently rotatable about a third roller (23).
12. The cam phasing mechanism (1) according to claim 10, wherein
the first roller (21) and the second roller (22) are coaxial.
13. The cam phasing mechanism (1) according to claim 12, wherein
the first roller (21) and the second roller (22) are rotatable
about a common axis, and wherein the first roller (21) is
restricted to a central location along the common axis.
14. The cam phasing mechanism (1) according to claim 10, wherein
the second roller (22) comprises two rollers, wherein one of the
two rollers is arranged on one side of the first roller (21) and
the other of the two rollers is arranged on another side of the
first roller (21).
15. A cam assembly (100) for an internal combustion engine and for
controlling actuation of a valve (505), the cam assembly (100)
comprising: a camshaft (120); an actuator (130) moveable by
rotation of the camshaft (120) for opening the valve (505) at a
reference position of rotation of the camshaft (120); and a force
transfer member (2a) interposed between the camshaft (120) and the
actuator (130) for transferring force between the camshaft (120)
and the actuator (130); wherein the force transfer member (2) is
selectively moveable by an adjuster (2b) to adjust the reference
position of rotation of the camshaft (120).
16. The cam assembly (100) according to claim 15, wherein the force
transfer member (2a) is selectively moveable either side (S1, S2)
of a reference plane (P) between an axis (115) of the camshaft
(120) and an axis (135) of the actuator (130).
17. The cam assembly (100) according to claim 15, wherein the
actuator (130) comprises a first surface (131) for avoiding contact
with the force transfer member (2a) and a second surface (132) for
engaging the force transfer member (2a).
18. The cam assembly (100) according to claim 17, wherein the force
transfer member (2a) comprises a first roller (21) for engaging the
camshaft (120) and a second roller (22) for engaging the second
surface (132) of the actuator (130).
19. The cam assembly (100) according to claim 18, wherein the first
roller (21) comprises a diameter that is greater than a diameter of
the second roller (22).
20. A valve train assembly (1000) for an internal combustion
engine, the valve train assembly (1000) comprising an exhaust valve
and a cam assembly (100) for actuating the exhaust valve, the cam
assembly (100) comprising: a camshaft (120); an actuator (130)
moveable by rotation of the camshaft (120) for opening the valve
(505) at a reference position of rotation of the camshaft (120);
and a force transfer member (2a) interposed between the camshaft
(120) and the actuator (130) for transferring force between the
camshaft (120) and the actuator (130); wherein the force transfer
member (2) is selectively moveable by an adjuster (2b) to adjust
the reference position of rotation of the camshaft (120).
Description
TECHNICAL FIELD
[0001] The present invention relates to valve train assemblies of
internal combustion engines, specifically to variable valve train
components of a valve train assembly.
BACKGROUND
[0002] Internal combustion engines, such as four-stroke diesel
engines, may comprise variable valve train components. Valve train
assemblies may include a camshaft that rotates with engine speed to
sequentially move a push rod, rocker arm and valve. An eccentric
cam lobe determines the movement of the push rod for each
revolution of the camshaft. For example, valve train assemblies may
comprise a variable valve lift to provide for control of an opening
of a valve (for example, control of an opening of an intake valve
and/or exhaust valve) by alternating between at least two or more
modes of operation (e.g. valve-lift modes). The timing and/or
duration of the valve lift may be controlled by the valve train
assembly. Optimising valve operations helps to reduce fuel
consumption, particularly when the engine speed and/or engine load
is varied.
SUMMARY
[0003] Aspects of the present invention are listed in the
accompanying claims.
[0004] Features of the present invention will now be described, by
way of example only, with reference to the accompanying drawings,
of which:
LIST OF FIGURES
[0005] FIG. 1 illustrates schematically a cam phasing mechanism for
a cam assembly of an internal combustion engine according to an
example;
[0006] FIG. 2 illustrates schematically a cross-sectional side view
of a cam phasing mechanism according to an example;
[0007] FIG. 3a illustrates schematically a cross-sectional side
view of a cam assembly according to an example;
[0008] FIG. 3b illustrates schematically an enlarged
cross-sectional side view of a force transfer member shown in FIG.
3a;
[0009] FIG. 4 illustrates schematically a part cross-sectional side
view of a valve train assembly according to an example;
[0010] FIG. 5 illustrates schematically a reference timing diagram
according to an example;
[0011] FIG. 6 illustrates schematically a timing diagram showing an
example of a late exhaust valve closing (LEVC) scenario according
to an example;
[0012] FIG. 7 illustrates schematically a part cross-sectional side
view of a valve train assembly according to another example;
[0013] FIG. 8 illustrates schematically a part cross-sectional side
view of an actuation assembly of the valve train assembly shown in
FIG. 7;
[0014] FIG. 9 illustrates schematically an arrangement of an
hydraulic circuit of the actuation assembly shown in FIG. 7;
[0015] FIG. 10 illustrates schematically a cross-sectional side
view of the actuation assembly shown in FIG. 7;
[0016] FIG. 11 illustrates schematically a cross-sectional side
view of an actuation mechanism of the actuation assembly shown in
FIG. 10;
[0017] FIGS. 12a to 12d illustrate schematically cross-sectional
side views of different positions of the actuation mechanism shown
in FIG. 11;
[0018] FIGS. 12B and 12B illustrate schematically cross-sectional
side views of different positions of the actuation assembly shown
in FIG. 10;
[0019] FIGS. 13 and 14 illustrate schematically the timing diagram
shown in FIG. 6 and the points on the timing diagram corresponding
to the different positions of FIGS. 12a to 12d;
[0020] FIG. 15 illustrates schematically a cross-sectional side
view of a motion controller shown in FIG. 10;
[0021] FIG. 16 illustrates schematically a side view of a camshaft
arrangement according to an example;
[0022] FIG. 17 illustrates schematically a cross-sectional side
view of a position of the actuation mechanism shown in FIG. 10;
[0023] FIG. 18 illustrates schematically a timing diagram showing
an example of a late intake valve closing (LIVC) scenario according
to an example;
[0024] FIGS. 19a and 19b illustrate schematically cross-sectional
side views of different states of the motion controller shown in
FIG. 15;
[0025] FIG. 20 illustrates schematically a timing diagram showing
an example of a combined late intake valve opening (EIVO) and early
intake valve closing (EIVC) scenario according to an example;
[0026] FIGS. 21a to 21f illustrate schematically cross-sectional
side views of different arrangements of the motion controller shown
in FIG. 15;
[0027] FIGS. 22 to 24 illustrate schematically the locations on a
timing diagram corresponding to the different arrangements of FIGS.
21a to 21f;
[0028] FIG. 25 illustrates schematically a camshaft arrangement for
a six cylinder internal combustion engine according to an
example;
[0029] FIG. 26 illustrates schematically a timing diagram of a
two-stroke engine brake system according to an example;
[0030] FIG. 27 illustrates schematically a top view of a valve
assembly according to an example;
[0031] FIG. 28a illustrates schematically an engine brake rocker
arm assembly according to an example;
[0032] FIG. 28b illustrates schematically an engine brake control
capsule of the engine brake rocker arm assembly of FIG. 28a;
[0033] FIG. 28c illustrates schematically an actuator of the engine
brake rocker arm assembly of FIG. 28a; and
[0034] FIG. 29 illustrates schematically a rocker arm arrangement
according to an example.
[0035] Throughout, like reference signs denote like features.
DESCRIPTION
[0036] Referring to FIG. 1 an example of a cam phasing mechanism 1
for a cam assembly 100 according to an example is shown. The cam
phasing mechanism 1 is suitable for a valve train assembly 1000 of
an internal combustion engine (not shown), as shown in FIG. 4. The
internal combustion engine may comprise six cylinders (not shown)
and may be a compression ignition (CI) engine suitable for diesel
fuel combustion. Preferably, the internal combustion engine is a
four-stroke combustion engine.
[0037] The cam assembly 100 shown in FIG. 1 comprises a camshaft
120 and an actuator 130 having an axis for opening a valve 505 at a
reference position of rotation of the camshaft 120. The camshaft
120 is rotatable about an axis (not shown). The reference position
is a position of angular rotation of the camshaft 120 about the
axis of the camshaft at which point the valve 505 is caused to open
and move away from a valve seat of a cylinder head. The cam phasing
mechanism 1 comprises a force transfer member 2a and an adjuster
2b. The force transfer member 2a is to be interposed between the
camshaft 120 and the actuator 130 of the cam assembly 100 so that
force is transferable between the camshaft 120 and the actuator
130. The adjuster 2b is to selectively move the force transfer
member 2a to bring about an adjustment of the reference position of
rotation of the camshaft 120.
[0038] FIG. 2 shows the cam phasing mechanism 1 in more detail. The
adjuster 2b comprises a first member 4, a second member 5 and a
third member 3. The third member 3 is described in more detail
below. The first member 4 is moveable relative to the second member
5 so that the force transfer member 2a is selectively moved
relative to the second member 5. This allows the reference position
of rotation of the camshaft 120 to be adjusted. The first member 4
is shown to be moveable through a centre of the second member 5.
That is, the second member 5 surrounds the first member 4 an at
least partially enclose the first member 4. While the second member
5 is configured to rotate about an axis, the first member 4 is
configured to move linearly along an axis. Each axis may be the
same. The first member 4 and second member 5 may be concentric.
[0039] In the example shown, the first member 4 is continuously
moveable relative to the second member 5 for continuously adjusting
the reference position of rotation of the camshaft 120 within a
predetermined range. The predetermined range may be 50 degrees of
rotation of the camshaft, corresponding to 100 crank angle degrees
(100 CAD). That is, the reference position of rotation of the
camshaft 120 at which the valve 505 is caused to open or close can
be shifted, i.e. phased, by 50 angular degrees of rotation of the
camshaft 120.
[0040] In the example provided, the first member 4 of the adjuster
2b is a threaded bushing and the second member 5 is a wheel gear.
That is, the first member 4 and second member 5 are engageable by
respective threaded portions. The respective threaded portions mesh
together to provide the required movement of the first member 4
relative to the second member 5 to allow a translational position
of the force transfer member 2a to be changed. As the second member
5 is rotated about an axis, the first member 4 is moved along the
second member 5 to a translated location of the first member 4'.
This movement is shown as translational motion of the first member
4 about a translation axis L in a first direction B. The axis of
rotation of the second member 5 may be coexist on translation axis
L. The first member 4 is configured to move up and down the
translation axis L. Movement of the first member 4 in the first
direction B may, for example, cause advance timing of the valve
505. That is, the valve 505 may open sooner in an engine cycle.
[0041] As shown in FIG. 2, the force transfer member 2a is spaced
from the first member 4 by the third member 3. The third member 3
comprises a lever arm 31 which is pivotable relative the first
member 4 and the second member 5. The pivot in this example is a
bearing 6. The lever arm 31 extends between a proximal portion 32
and a distal portion 33 of the third member 3. The proximal portion
32 is shown to be moveable within the second member 5 and the
proximal portion 32 moves with the first member 4. The third member
3 may be generally Y-shaped such that the distal portion 33 is a
bifurcated portion. In this example, the bifurcated portion extends
around axial ends of the force transfer member 2a to enclose the
force transfer member 2a between branches of the bifurcated
portion. When the third member 3 is generally Y-shaped, the lever
arm 31 comprises a stem portion from which the branches of the
bifurcated portion extend.
[0042] As discussed, the pivotable motion of the lever arm 31 is
achieved by the bearing 6. The bearing 6 comprises a portion that
is coupled to the first member 4. The bearing 6 is therefore
configured to experience the same translational motion of the first
member 4 with respect to the second member 5, which is represented
by a translated location of the bearing 6' in FIG. 2. The bearing 6
allows the force transfer member 2a to freely pivot about the first
member 4. A first portion of the first member 4 comprises an
abutment to contact the lever arm 31 of the third member 3 and
prevent pivoting motion in one rotational direction. Equally, a
second potion of the first member 4 comprises an abutment to
contact the lever arm 31 of the third member 3 and prevent pivoting
motion in another rotational direction. Each abutment may be
opposite each other and may be on an internal surface of the first
member 4. Each abutment may be diametrically opposed.
[0043] The cam phasing mechanism 1 of FIG. 2 comprises a driving
member 10 for driving the second member 5 of the adjuster 2b. The
driving member 10 may be electromechanically controlled and driven
by an electrical signal. An axis of rotation of the driving member
10 for driving the driving member 10 in rotation direction R2 is
perpendicular to an axis of rotation of the second member 5. The
driving member 10 may be a worm gear. The driving member 10
comprises a first threaded portion 11 which engages with a second
threaded portion 52 of the second member 5. The second member 5
comprises two threaded portions. The threaded portions are shown on
opposite sides of the second member 5. In the example of FIG. 2,
the second threaded portion 52 is located on an external side of
the second member 5. An additional third threaded portion 53 is
located on an internal side of the second member 5. The third
threaded portion 53 is configured to mesh with a fourth threaded
portion 41 of the first member 4. The engagement of the first to
fourth threaded portions 11, 52, 53, 41, movement of which is
driven by the driving member 10, causes the force transfer member
2a to move and affect the valve timing. The relative movement of
the first member 4 and second member 5 is prevented when the
driving member 10 is rotationally fixed. However, the third member
3, and thus the force transfer member 2a, can still freely pivot to
allow the transfer of force between the camshaft 120 and actuator
130.
[0044] In the example shown in FIG. 2, the force transfer member 2b
is moveable about three axes. A first axis of movement of the force
transfer member 2b is the axis about which the force transfer
member 2b moves translationally. This is caused by the relative
movement of the first member 4 and second member 5. A second axis
of movement of the force transfer member 2b is the axis about which
the force transfer member 2b pivots. The pivoting motion causes the
force transfer member 2b to move relative to the first member 4 and
the second member 5. The second axis of movement is caused by the
transfer of force between the camshaft 120 and the actuator 130. A
third axis of movement of the force transfer member 2b is the axis
about which a roller assembly rotates. The third axis of movement
may be parallel to the first axis of moment. Either or both of the
first and third axes of movement may be perpendicular to the
secocnd axis of movement. The roller assembly is shown in FIG. 3b
and is described in more detailed below. The roller assembly
reduces the friction between the engaging parts of the camshaft 120
and the actuator 130 with the force transfer member 2b so that the
transfer of energy is more efficient. The roller assembly also
helps to reduce wear and noise of the respective engaging
parts.
[0045] The cam phasing mechanism 1 of FIG. 2 comprises a housing 7
to enclose the moving parts of the cam phasing mechanism 1. The
housing 7 may be part of a case 8 which encloses the camshaft, such
as a cam cover or crankcase. In FIG. 2, the housing 7 and the case
8 are separate and may be interposed by a gasket to prevent
lubricant oil leakage from the cam phasing mechanism 1. The housing
7 and the case 8 may therefore be coupled together by at least one
fastener, such as a bolt. The housing 7 is shown with a locating
member 71 which helps to control an axial position of the second
member 5. The locating member 71 defines a recess into which the
second threaded portion 52 is located. The case 8 is also shown
with a locating member 81 which interacts with the locating member
71 of the housing 7 to accommodate the first member 5 of the
adjuster 2b. The first member 5 of the adjuster 2b is shown with a
locating member 51 which is a protrusion to fit inside a recess of
the locating member 81.
[0046] Turning to FIG. 3a, a schematic illustration of a
cross-sectional side view of a cam assembly 100 according to an
example is shown. The cam assembly 100 comprises the cam phasing
mechanism 1 shown in FIG. 2. The cam phasing mechanism 1 engages
with the camshaft 120 and actuator 130 to open and close a valve
505. The actuator 130 in this example is a curved mushroom type
lifter that is configured to act on a push rod which then acts on a
rocker assembly to open the valve 505. This operation is discussed
in relation to FIG. 4. The actuator 130 moves in a second direction
D, which is shown to be perpendicular to the first direction B.
[0047] The camshaft 120 shown in FIG. 3a, for example, comprises at
least one cam 121 accommodated within a housing 124. Each cam 121
has a base surface 123a and a raised profile 123b of a cam lobe
122. When the cam 120 is orientated such that the base surface 123a
is engaged with the force transfer member 2a, no actuation force is
transmitted to the actuator 130, via the force transfer member 2a,
for opening the valve 505. The camshaft 120 is configured to rotate
about a camshaft axis 125 in direction R1. As the camshaft 120
rotates, the raised profile 123b engages with the force transfer
member 2a and the raised profile 123b applies a force, via the
force transfer member 2a, to the actuator 130. The actuator 130
subsequently moves in the second direction D to act on a rocker arm
assembly and open the valve 505. The force transfer member 2a
thereby acts as an intermediate member to transmit an actuation
force from the camshaft 120 to the actuator 130 in order to open
the valve 505.
[0048] As is best shown in FIG. 3a, the force transfer member 2a is
selectively moveable either side S1, S2 of a reference plane P
between an axis 115 of the camshaft 120 and an axis 135 of the
actuator 130. The axis 135 of the actuator 130 is a pivot of a push
rod and lifter, whereby the push rod pivots about the axis 135 as
the lifter moves along a predefined path. The force transfer member
2a is shown on a first side S1 when the adjuster 2b is at one limit
of movement. At another limit of movement of the adjuster 2b the
force transfer member 2a can move through the reference plane and
to a second side S2. This movement is possible while the camshaft
120 rotates and the force transfer member 2a pivots.
[0049] An enlarged view of a roller assembly region A of the force
transfer member 2a is shown in FIG. 3b. Here, the force transfer
member 2a comprises a first roller 21 for engagement with the
camshaft 120 of the cam assembly 100 and a second roller 22 for
engagement with the actuator 130 of the cam assembly 100. The first
roller 21 and the second roller 22 are each independently rotatable
about a third roller 23. In the example shown, the first roller 21
and the second roller 22 are coaxial. The actuator 130 comprises a
first surface 131 and a second surface 132. The second surface 132
of the actuator 130 engages with the second roller 22 of the force
transfer member 2a, whereas the first surface 131 of the actuator
130 avoids contact with the force transfer member 2a. The first
surface 131 is shown as a groove in the actuator 130. In the
example shown, the first surface 131 of the actuator 130 is spaced
away from both the first roller 21 and the second roller 22 so that
only the second surface 132 of the actuator engages with the
respective portion of the force transfer member 2a, i.e. the second
roller 22. In the example shown, the first roller 21 is arranged
centrally, whereas the second roller 22 is exposed at either side.
The central location may refer to a location along a shared axis of
rotation of the first roller 21 and second roller 22. That is, the
first roller 21 and the second roller 22 are rotatable about a
common axis and the first roller 21 is restricted to a central
location along the common axis. The first roller 21 is shown with a
greater diameter than the second roller 22. The second roller 22
may comprise two rollers, wherein each of the two rollers are
arranged either side of the first roller 21. That is, one of the
two rollers is arranged on one side of the first roller 21 and the
other of the two rollers is arranged on another side of the first
roller 21. The first surface 131 and the second surface 132 of the
actuator 130 are concave and may complement the curvature of the
base surface 123a of the cam 121.
[0050] FIG. 4 shows a valve train assembly 1000 according to an
example. The valve train assembly 1000 is suitable for an internal
combustion engine (not shown). The valve train assembly 1000
comprises a valve assembly 500 which may be a pair of exhaust
valves including the valve 505 and the cam assembly 100 as
previously described for actuating the valve 505 of the valve
assembly 500. As the camshaft 120 rotates, force is transmitted to
the force transfer member 2a of the cam assembly 100 when the
raised profile 123b of the cam 121 engages with the force transfer
member 2a. Subsequently, the actuator 130 moves a push rod 200 to
cause a rocker arm of a rocker arm assembly 300 to pivot and press
a valve bridge assembly 400 to open the valve 505 by pressing a
valve stem 501 and moving a valve head 502. The valve 505 may be an
exhaust valve that opens an exhaust port (not shown) to allow
exhaust gas to leave a combination chamber of an internal
combustion engine.
[0051] FIG. 5 illustrates schematically a reference timing 1100
diagram according to an example. The reference timing 1100 diagram
shows the amount of lift of an intake and exhaust valve. That is,
the degree of movement of the intake valve and exhaust valves. The
reference timing of the exhaust valve 1120 and the reference timing
of the intake valve 1110 is shown together. In the scenario show, a
region of overlap E1 is present. This is when both the intake and
exhaust valves are simultaneously open, which, in the example
shown. occurs a few degrees either side of top dead centre (TDC) of
the piston stroke. The exhaust valve opens at a valve opening 1121
timing, reaches a maximum lift 1123 and then closes at a valve
closing 1122 timing. Equally, the intake valve opens at a valve
opening 1111 timing, reaches a maximum lift 1113 and then closes at
a valve closing 1112 timing.
[0052] The cam phasing mechanism 1 is configured to change the
timing at which a valve, such as the exhaust valve opens. In the
example, shown, a valve phasing range F represents the degree to
which the reference timing of the exhaust valve 1120 can be changed
to advance or retard the opening timing of the exhaust valve. For
example, the early phasing 1101 of the valve opening, e.g. early
exhaust valve opening (EEVO) may be up to 100 crank angle degrees,
corresponding to 50 camshaft angle degrees from the reference
timing of the exhaust valve 1120. Movement of the timing of the
exhaust valve opening towards the reference timing of the exhaust
valve 1120 may be considered to be late phasing 1102 in this
example. The EEVO scenarios moves the timing of the maximum lift of
the exhaust valve towards bottom dead centre (BDC) timing of a
piston of the internal combustion engine.
[0053] FIG. 6 shows a schematic example timing diagram of an
exhaust valve event The timing diagram is an example of an
elongated timing 1200 to increase the valve lift duration. The
intake valve timing 1110 in FIG. 6 is the same as the reference
intake valve timing shown in FIG. 5 and there is no change to the
timing in this specific example. However, the reference timing of
the exhaust valve 1120 shown in FIG. 5 has been advanced and
elongated to create a different region of overlap E2. A lost motion
region K is shown on a closing side of the exhaust valve. The lost
motion region K maintains the exhaust valve in a lift position such
that the exhaust port remains open. In this instance, the camshaft
is disengaged with the valve while the valve is kept open. This
process will be described in further detail below. Although a fixed
lift position of the exhaust valve is shown in FIG. 6, the lost
motion does not have to result in a fixed position and may be
represented by reduced motion of the exhaust valve closing
event.
[0054] FIG. 7 shows a schematic illustration of a part
cross-sectional side view of a valve train assembly 2000 according
to an example. Here, a set of components for an intake side and an
exhaust side are shown. For example, an intake cam 111 causes an
intake push rod 210 to exert a force to control the actuation of a
pair of intake valves including an intake valve 515 by sequentially
transferring force to an intake rocker arm assembly 310 and an
intake valve bridge assembly 410. The intake valve bridge assembly
410 exerts a force on the intake valve stem 511 of an intake valve
assembly 510 which causes the intake valve head 512 to move about
an intake valve seat of the cylinder head. Equally, an exhaust cam
121 causes an exhaust push rod 220 to exert a force to control the
actuation of a pair of exhaust valves including an exhaust valve
525 by sequentially transferring force to an exhaust rocker arm
assembly 320 and an exhaust valve bridge assembly 420. The exhaust
valve bridge assembly 420 also exerts a force on the exhaust valve
stem 521 which causes the exhaust valve head 522 to move about an
exhaust valve seat of the cylinder head. As shown in the example of
FIG. 7, the intake cam 111 and exhaust cam 121 are part of the same
camshaft, which rotates about a single, common axis. Also shown in
FIG. 7 is an actuation assembly 600 which is interposed between the
push rods 210, 220 and respective rocker arm assemblies 310,
320.
[0055] As shown in FIG. 8, the actuation assembly 600 comprises an
actuation mechanism 700 and a motion controller 800. The actuation
mechanism 700 may be considered a first actuation arrangement and
the motion controller 800 may be considered a second actuation
arrangement. In the example shown, the actuation mechanism 700 and
motion controller 800 are in communication with each other,
whereby, in one example, the motion controller 800 is configured to
influence an operation of the actuation mechanism 700.
[0056] In the example shown in FIG. 9, the actuation assembly 600
is hydraulically controlled and is shown with a hydraulic circuit.
Therefore, operation of the actuation assembly 600 may be affected
by a working fluid, such as oil which is moved around the hydraulic
circuit by a pump (not shown). When the working fluid is
pressurised, respective parts of the actuation assembly 600 can be
moved to bring about a change in valve timing. The hydraulic
circuit comprises a pressurising device which is shown as an
accumulator 601. The accumulator 601 comprises a moveable member,
such as a piston 605, that is moveable with respect to a housing
604 back and forth along a reciprocation path C. The accumulator
piston 605 is biased towards a first position by a resilient device
such as a spring S. The spring S acts on the piston 605 to
pressurise the working fluid. One function of the accumulator 601
is to accommodate changes in the volume of working fluid passing
into and out of the actuation assembly 600. The working fluid is
moved away from the accumulator 601 by a pump. The working fluid is
then supplied, by a first supply line 602 of the hydraulic circuit,
to the motion controller 800 and, by a second supply line 603 of
the hydraulic circuit, to the actuation mechanism 700. Respective
return lines 606, 607 are then used to transport the working fluid
away from the actuation mechanism 700 and the motion controller
800. The hydraulic circuit is provided as a closed system.
[0057] In FIG. 10, the actuation mechanism 700 and the motion
controller 800 of the actuation assembly 600 are shown in more
detail. The actuation mechanism 700 and the motion controller 800
comprise a network of passageways that form part of the hydraulic
circuit. In the example shown, a common passageway 608 is shown to
interconnect the respective passageways of the actuation mechanism
700 and the motion controller 800. The actuation assembly 600 is
shown with two force transmitters 610, 620. A first force
transmitter 610 predominantly for controlling actuation of an
intake valve 515 and a second force transmitter 620 is
predominantly for controlling actuation of an exhaust valve 525.
Each force transmitter 610, 620 engages with the respective push
rod 210, 220 and camshaft 111, 121 and rocker arm assembly 310,
320. The actuation mechanism 700 and the motion controller 800 are
explained in further detail below.
[0058] FIG. 11 shows a schematic cross-sectional side view of the
actuation mechanism 700 of the actuation assembly 600 shown in FIG.
10. The force transmitter 610 of the actuation assembly 600
comprises a first actuator 710 and a second actuator 720. The
second actuator 720 may be a hydraulic lock piston such that a
resistance to movement of the second actuator 720 is achieved by
hydraulic force. The first actuator 710 and the second actuator 720
are moveable relative each other. The relative movement may be
along a common axis of motion M1. The first actuator 710 is
engageable with the exhaust push rod 220 and the exhaust rocker arm
assembly 320. However, the second actuator 720 is not engageable
with the exhaust push rod 220 but is engageable with the exhaust
rocker arm assembly 320. Each of the first actuator 710 and the
second actuator 720 comprise a respective engagement face to
directly abut an engagement face 323a of a joint 321 of the exhaust
rocker arm assembly 320. The engagement face 721 of the second
actuator 720 is spaced from the joint 321 because in the
orientation shown in FIG. 11, the first actuator 710 is directly
engaging with the joint 321 without engagement of the second
actuator 720. As the joint 321 is pressed by an engagement face of
the first actuator 710 a ball 322 moves within a socket 323 of the
exhaust rocker arm assembly 320.
[0059] The first actuator 710 comprises a slave part 710a and a
master part 710b that are separable from each other. Each of the
slave part 710a and the master part 710b is shown as a rod that are
moveable with respect to each other. The slave part 710a is a first
rod that is moveable within a hole provided in the second actuator
720. The master part 710b is a second rod that is moveable within a
hole provided in a housing 770 of the actuation mechanism 700. In
the orientation shown in FIG. 11, the slave part 710a and the
master part 710b are engaged with each other in an engagement area
704 in an engagement position.
[0060] The actuation mechanism 700 comprises a controller that
allows a working fluid to enter the housing 770 via a fluid inlet
730. The controller in this example is a spool valve 750. The spool
valve 750 comprises a rotating member 751 such as a cam and a
sliding member 752 which acts as a valve. As the rotating member
751 rotates about a motion axis M2 in direction R3, a raised
profile of the rotating member 751 causes the sliding member 752 to
move and allow the working fluid to communicate between the fluid
inlet 730 and an intermediate passageway 731. The intermediate
passageway 731 contains a non-return valve 760. The non-return
valve 760 comprises a moveable part 761 such as a ball and a
resilient member such as a spring S. The moveable part 761 is
moveable relative to a base 762 to open the non-return valve 760 by
moving the moveable part 761 along a motion axis M3 and allow the
working fluid to flow to a working zone 733. The working zone 733
is a reservoir for causing hydraulic lock of the second actuator
720 and varies in volume. The working zone 733 comprises a reserve
passageway 734 which allows a volume of working fluid to remain in
the working zone 733 when the second actuator 720 is moved fully
down by the exhaust rocker arm assembly 320 when the exhaust valve
525 is closed. Finally, working fluid is removed from the working
zone 733 through a fluid outlet 735.
[0061] FIGS. 12a to 12d schematically show cross-sectional side
views of the actuation mechanism 700 at different stages of
operation of the actuation mechanism 700 to highlight the different
positions of the various components. The positions shown in FIGS.
12a to 12d are performed when the exhaust valve 525 is moving away
from the position of maximum lift and is therefore closing the
exhaust port.
[0062] FIG. 12a shows the actuation mechanism 700 arranged in a
first position 700-1. In the first position 700-1, the first
actuator 710 is configured to control actuation of the exhaust
valve 525. The engagement area 740 is therefore defined by the
first actuator 710 only and not the second actuator 720. In the
first position 700-1, the socket 323 of the rocker exhaust arm
assembly 320 engages with the slave part 710a of the first actuator
710 which is engaged with the master part 710b and exhaust push rod
220. The location of the exhaust valve at the first position 700-1
of the actuation mechanism 700 is shown in FIG. 13. When the
engagement area 740 is defined by the engagement of the slave part
710a with the socket 323 the exhaust valve closes according to the
shape of the curve shown in the reference timing of FIG. 5.
Rotation of the raised profile 123b of the exhaust camshaft 121
causes the slave part 710a and master part 710b of the first
actuator 710 to move in contact with each other at the same rate.
This is a movement in a valve closing direction H, which may
correspond to a downward direction. In the first position 700-1,
the spool valve 750 is open such that the working fluid could be
pumped into the working zone 733. However. to prevent movement of
the second actuator 720 in the valve closing direction H, the fluid
outlet 735 is closed. Therefore, even though the working fluid may
be pumped, the first position 700-1 represents a no flow condition
of the working fluid inside the actuation mechanism 700. This helps
to hydraulically lock the second actuator 720 in position so that
no movement of the second actuator 720 is possible.
[0063] In order to position the second actuator 720 in the correct
location in the housing 770 when in the first position 700-1, the
working fluid forces the second actuator 720 to an extent of the
housing 770, which may correspond to an upward direction. The
second actuator 720 therefore comprises an abutment which engages
with a corresponding abutment of the housing 770 as shown in
abutment area N. The second actuator 720 is held in abutment with
the housing 770 by a pressure of the working fluid as well as the
action of the non-return valve 760 which prevents working fluid
from escaping the working zone 733.
[0064] Each rocker arm assembly 310, 320 is biased to close the
valve as a default configuration. Therefore, the exhaust rocker arm
assembly 320 exerts a force against the first actuator 710. As the
exhaust camshaft 121 is rotated, the socket 323 is brought towards
the second actuator 720. During this event, the exhaust valve 525
continues to close, as shown by the downward arrow in FIG. 13.
[0065] FIG. 12b shows the actuation mechanism 700 when arranged in
a second position 700-2. Here, actuation of the exhaust valve 525
is controlled by the second actuator 720 rather than the first
actuator 710. In this position, the movement of the exhaust valve
525 is brought to a gradual stop, as shown by the corresponding
location of the second position 700-2 in FIG. 13. The exhaust valve
525 remains open at a certain lift, for example 3 mm for a
predetermined crank angle degrees. When lifting the exhaust valve
525 the exhaust valve 525 is raised away from an exhaust valve
seat. The second actuator 720 now acts as a hydraulic lock piston
to prevent any movement of the exhaust rocker arm assembly 320 in
the valve closing direction H. Given that the fluid outlet 735 and
the non-return valve 760 are closed, the working fluid cannot leave
the working zone 733 and the second actuator 720 is held in
position relative to the housing 770. In the second position 700-2,
the engagement area 740 comprises respective engagement portions of
the first actuator 710 and second actuator 720. This engagement
area 740 in the second position 700-2 is therefore greater than the
engagement area 740 in the first position 700-1. Nevertheless, in
some examples, the engagement area 740 in the second position 700-2
may only comprise the second actuator 720 and not the first
actuator 710.
[0066] As discussed above, the movement of the first actuator 710
is governed by a first driver and the movement of the second
actuator 720 is governed by a second driver that is different to
the first driver. In the example provided, the first driver
comprises a mechanical force and the second driver comprises a
hydraulic force.
[0067] In FIG. 12c, the actuation mechanism 700 is arranged in a
third position 700-3. At this point, the fluid outlet 735 is open
and working fluid can flow through the working zone 733. A
controller may control release of working fluid from the fluid
outlet 733 to reduce the volume of working fluid within the working
zone 733. The controller may hydraulically control movement of the
second actuator 720. This reduces the pressure inside the working
zone 733 and a volume of working fluid in the working zone 733
starts to decrease. Between the second position 700-2 and the third
position 700-3, the master part 710b moves away from the slave part
710a as the raised profile 123b continues to rotate to create a gap
G that is greatest just before the exhaust valve 525 resumes a
closing action. In the third position 700-3, the resilience of the
rocker arm assembly 320 and valve assembly 520 forces the second
actuator 720 to move downward towards a lower part of the housing
770. The location of the third position 700-3 in the valve timing
diagram is shown in FIG. 14 using the corresponding reference value
700-3.
[0068] The period between the second position 700-2 and the third
position 700-3 may be changed by changing the timing of opening the
exhaust valve 525. That is, the motion of the second actuator 720
towards the lower part of the housing 770 is independent of
rotation of the exhaust camshaft 121. In this instance, the period
at which the exhaust valve 525 is constantly kept open is variable.
Specifically, the motion of the second actuator 720 is independent
of rotation of the exhaust camshaft 121 when the raised profile
123b of the exhaust camshaft 121 no longer raises the exhaust valve
525. That is the exhaust valve closing (EVC) event is always
substantially at the same point and is independent of the timing of
the exhaust valve opening (EVO). Selecting the timing of the
opening of the exhaust valve 525 to begin earlier than that of a
standard exhaust valve lift event (e.g. that shown un the reference
timing diagram of FIG. 5) is referred to herein as Early Exhaust
Valve Opening (EEVO).
[0069] In some instances, for example in the example provided, the
first force transmitter 610 controls the opening of the fluid
outlet 735 and acts as a controller. The first force transmitter
610 may comprise a channel which allows the fluid outlet 735 to
communicate with the return line 606 of the hydraulic circuit. This
may occur when the intake valve 515 is lifted to around 0.5 to 0.7
mm of lift since the first force transmitter 610 governs the
lifting operation of the valve to raise the intake valve 515 from
the intake valve seat (not shown). In this instance, the timing
location of the third position 700-3 is determined by the intake
valve operation. The exhaust valve 525 operation and the intake
valve operation 515 are therefore directly linked by the actuation
assembly 600.
[0070] FIG. 12d shows a fourth position 700-4 of the actuation
mechanism 700. The location of the fourth position 700-4 on the
valve lift diagram is shown in FIG. 14 with corresponding notation
700-4. Between the third position 700-3 and the fourth position
700-4, the second actuator 720 continues to be moved downward by
the resilience of the exhaust rocker arm assembly 320 and exhaust
valve assembly 520. The second actuator 720 comprises a damper 705
that is used to decelerate the bringing together of the second
actuator 720 to the housing (valve closed position) 770. The damper
705 shown is an arcuate portion. The arcuate portion may be convex.
Additionally, the arcuate portion may be conical in shape. A damper
with a conical shape allows a discharge area to gradually vary in
order to provide a gradual closure of the exhaust valve 525. Due to
the conical shape, the discharge area decreases at a lower rate
with constant movement of the second actuator 720 to allow working
fluid to more gradually flow out of the working zone 733 through
the fluid outlet 735. The working zone 733 comprise a reserve
passageway 734 which comprises working fluid in the fourth position
700-4. The reserve passageway 734 is formed from a space between
the slave part 710a and the second actuator 720. In the region of
the reserve passageway 734 the second actuator 720 is sized to
accommodate a portion of the master part 710b but does not come
into contact with the master part 710b since the master part 710b
engages with the slave part 710a.
[0071] The operation of the actuation mechanism 700 sequentially
between the first to fourth positions 700-1 to 700-4 elongates the
period during which the exhaust valve is open compared to the
period shown in the reference timing diagram of FIG. 5. When the
actuation mechanism 700 is used in combination with the cam phasing
mechanism 1 as previously described a size of the elongation is
variable. When the actuation mechanism 700 is further combined with
the motion controller 800 as shown in FIG. 10, the exhaust valve
closing (EVC) timing is determined by a pressure release portion
802. The pressure release portion 802 allows the working fluid to
discharge out of the working zone 733 and through the fluid outlet
735. When combining the actuation mechanism 700 with the motion
controller 800, the fluid outlet 735 acts as one part of the common
passageway 608. Given that the pressure release portion 802 of the
motion controller 800 may be controlled by an intake camshaft 111,
the actuation mechanism 700 may move to the third position 700-3 by
movement of the intake camshaft 111 rather than the exhaust
camshaft 121. This scenario is shown in FIGS. 12B and 12C whereby a
direction of movement of a motion controller 800 and corresponding
pressure release portion 802 is shown by arrow J. FIG. 12B
corresponds to the timing location of the second position 700-2, as
described in FIG. 12b. FIG. 12C corresponds to the timing location
of the third position 700-3, as described in FIG. 12c.
[0072] FIG. 15 shows a schematic illustration of a cross-sectional
side view of the motion controller 800 shown in FIG. 10. The force
transmitter 620 of the actuation assembly 600 comprises a first
part 810 and a second part 820. The first part 810 and the second
part 820 may operate as a hydraulic lock piston such that a
resistance to movement of both the first part 810 and the second
part 820 is achieved by hydraulic force. The first part 810 and the
second part 820 are moveable relative each other. The relative
movement may be along a common axis of motion M1. The second part
820 is engageable with the intake push rod 210 but is not
engageable with the intake exhaust rocker arm assembly 310. The
first part 810 is not engageable with the intake push rod 210 but
is engageable with the intake rocker arm assembly 310. Each of the
first part 810 and the second part 820 comprise a respective
engagement face to directly abut the other part. The first part 810
comprises a further engagement face to abut a joint 311 of the
intake rocker arm assembly 310. In FIG. 15, the first part 810 is
directly engaging with the joint 311 without respective engagement
faces of the first part 810 and second part 820 engaging with each
other. A resilient member such as a spring S, is used to separate
the first part 810 and second part 820. The joint 311 therefore
presses against an engagement face of the first part 810 at
engagement area 840 and a ball 312 of the joint 311 moves within a
socket 313 of the joint 311.
[0073] The first part 810 and the second part 820 are separable
from each other. Each of the first part 810 and the second part 820
are shown as a cylinder that each have a cavity 811, 821 for being
filled by the working fluid. Together the cavities 811, 821 form a
reservoir. As the first part 810 and the second part 820 move with
respect to each other, the size of the reservoir changes even
though the size of the cavities 811, 821 remain fixed. In the
orientation shown in FIG. 15, the motion controller 800 is in an
unlocked state such that the second part 820 is moveable towards
the first part 810 by the camshaft 111 without imparting a lifting
force to the intake valve 515. The motion controller 800 may be
moved to a locked state before the intake valve 515 is opened
whereby the first part 810 and second part 820 are brought together
and engage. The spring S resists relative movement between the
first part 810 and the second pat 820 in the unlocked state.
[0074] The motion controller 800 comprises a controller that allows
a working fluid to enter the housing 870 via a fluid inlet 831. The
controller in this example is a non-return valve 860. The
non-return valve 860 comprises a moveable part 861 such as a ball,
a resilient member such as a spring S and a switch 862 for opening
and closing the non-return valve 860. The moveable part 861 is
moveable relative to the switch 862 to open the non-return valve
860 by moving the moveable part 861 along a motion axis M3 and
allow the working fluid to flow to a working zone 833. The working
zone 833 is the reservoir for causing hydraulic lock of the first
part 810 and second part 820 and varies in volume. The working zone
833 comprises a port 832 which allows a volume of working fluid to
fill or be released in the working zone 833 when the second part
820 is moved away from the first part 810 to allow the fluid inlet
831 to communicate with the cavities 811, 821 of the respective
first part 811 and second part 821. The working fluid can be
removed from the working zone 833 through the fluid inlet 831 when
the motion controller 800 is move to a locked state and the switch
862 is open in the position shown in FIG. 15. In this position, the
moveable member 861 no longer acts as a one-way valve and working
fluid may flow in either direction through the non-return valve
860.
[0075] Also shown in FIG. 15 is a further controller that allows a
working fluid to leave the housing 870 via a fluid outlet 835c. The
controller in this example is a spool valve 850. The spool valve
850 comprises a rotating member 851 such as a cam and a sliding
member 852 which acts as a valve. As the rotating member 851
rotates about a motion axis M2 in direction R3, a raised profile of
the rotating member 851 causes the sliding member 852 to move and
allow the working fluid to communicate between a fluid inlet 835b
and a fluid outlet 835c.
[0076] A further fluid inlet 830 is shown that is communicable with
a further fluid outlet 835a when a pressure release portion 802 is
aligned with the inlet 830 and outlet 835a. The pressure release
portion 802 is used to relieve pressure from the working zone 733
of the actuation mechanism 700 as previously described.
[0077] FIG. 16 illustrates schematically a side view of a camshaft
arrangement according to an example. The camshaft shown is the
intake camshaft 110. The intake camshaft 110 comprises a raised
profile with two portions, each portion is described herein as a
first raised profile 113b formed from a first cam lobe 112a and a
second raised profile 113c formed from a second cam lobe 112b. The
first raised profile 113b is more prominent that the second raised
profile 113c. That is, the first raised profile 113b protrudes
further from a base surface 113a that the second raised profile
113c. Therefore, when the intake camshaft 110 rotates about the
camshaft axis 115 in the direction shown (clockwise), the first
raised profile 113b engages with the actuator 130 before the second
raised profile 113c. The rotation of the intake camshaft 110 with
such a first raised profile 113b followed by such a second raised
profile 113c is arranged to produce the valve timing diagram shown
in FIG. 18.
[0078] The camshaft arrangement shown in FIG. 16 may be used
without the motion controller 800. However, when the camshaft
arrangement is used with the motion controller 800, the motion
controller is provided in a spaced arrangement shown in FIG. 17.
Here, the non-return valve 860 and the spool valve 850 are both
closed so that working fluid is retained in the reservoir and a
size of the port 832 is maximised. In this arrangement the first
part 810 and second part 820 of the motion controller 800 are
spaced apart and held relative to one another by a hydraulic lock.
The action of the camshaft shown in FIG. 16 is therefore the
dictating factor that produces the valve timing diagram of FIG. 18
and particularly the lost motion region Q (i.e. a region of no
valve lift). In this instance, the intake valve 515 operation is
elongated and is referred to herein as Late Intake Valve Closing
(LIVC).
[0079] FIGS. 19a and 19b schematically show cross-sectional side
views of the motion controller 800 in different states of operation
to highlight the different positions of the various components. The
positions shown in FIGS. 19a and 19b are performed when the intake
valve 515 is closed.
[0080] The first state is an unlocked state 800-1 of the motion
controller 800. In the unlocked state 800-1, the first part 810 and
second part 820 of the motion controller 800 are separated by the
port 832. The port 832 is closed when the first part 810 and second
part 820 are brought together as shown in the locked state 800-2.
When in the unlocked state 800-1, the second part 820 is moveable
towards the first part 810 in valve opening direction J by the
raised profile of the cam lobe of the camshaft 111 without
imparting a lifting force to the intake valve 515. A resistance to
relative movement between the first part 810 and the second part
820 in the unlocked state 800-1 is provided by a resilient member
such as the spring S. FIG. 20 is a valve timing diagram showing
reference timing 1110 of the intake valve 515 and the stunted
timing 1210 brought about by the motion controller 800. The stunted
timing 1210 is a reduced period of intake valve 515 opening
compared to the reference timing 1110 which causes earl intake
valve opening (EIVO) as well as early intake valve closing (EIVC)
operations. The unlocked position is shown by notation 800-1. Here,
the intake valve 515 is closed despite the raised profile of the
camshaft acting on the second part 820 of the motion controller 800
and lifting the second part 820 in valve opening direction J. The
intake valve 515 therefore does not open until the motion
controller 800 is arranged in the locked state 800-2 shown in FIG.
19b.
[0081] In the unlocked state 800-1, shown in FIG. 19a, the
reservoir formed by the respective cavities 811, 821 of the first
part 810 and the second part 820 further comprises the port 832
that is communicable with the fluid inlet 831. However, in the
locked state 800-2, as shown in FIG. 19b, the switch 862 of the
motion controller 800 is switched to a position at which the fluid
inlet 831 becomes a two-way passageway to allow working fluid to be
released as a fluid outlet from the reservoir. Therefore, as the
motion controller 800 continues to move in the valve opening
direction J, the intake valve 515 begins to open because the force
is transmitted by mechanical coupling of the first part 810 and
second part 820. Further rotation of the intake camshaft 110 causes
the raised profile to open the intake valve 515. The position of
the locked state 800-2 is shown on the valve timing diagram of FIG.
20. As the motion controller 800 continues on the valve closing
direction H the lost motion region K is not imparted on the valve
because the intake valve 515 has already closed (see FIG. 20). The
loss in intake valve 515 lift is shown as 3 mm.
[0082] FIGS. 21a to 21f schematically show cross-sectional side
views of the motion controller 800 in different arrangements to
highlight the different positions of the various components. The
positions shown in FIGS. 21a to 21f are performed in relation to
the intake valve 515.
[0083] A first arrangement 800a of the motion controller 800 is
shown in FIG. 21a with the corresponding location on the valve
timing diagram in FIG. 22. The first arrangement 800a is the same
as the unlocked state 800-1, shown in FIG. 19a, expect that the
switch 862 of the non-return valve 860 is closed to activate the
non-return function (i.e. one-way flow) of the non-return valve.
That is, working fluid in the fluid can enter the inlet 831 and
reach the port 832 of the reservoir because the moveable part 861
can move against the spring S under a pumped flow of the working
fluid by the pump (not shown). However, working fluid cannot leave
the reservoir (comprising the first cavity 811, the second cavity
821 and the port 832) or the fluid inlet 831 passageway. Therefore,
although the port 832 is aligned with the fluid inlet 831 the
working fluid cannot leave the reservoir because of a back pressure
of working fluid from the fluid inlet 831. In this instance, the
first part 810 is fixed relative to the second part 820. The fixing
is achieved by hydraulic lock.
[0084] Rotation of the intake camshaft 111, causes the force
transmitter 601 to move relative to the housing 870 of the motion
controller 800 in valve opening direction J. That is, the first
part 810 and the second part 820 move in combination (i.e. in
tandem) to open the intake valve 515 and raise the intake valve 515
away from the intake valve seat. In this example, the direction of
movement of the first part 810 and second part 820 is an upward
direction.
[0085] As the combined first part 810 and the second part 820 move
in a direction to open the valve (i.e. the valve opening direction
J), the port 832 becomes aligned with the fluid inlet 835b. Given
that the spool valve 850 is in an open position by turning the
rotating member 851, working fluid can be transferred through an
aperture in the sliding member 852 and out through the fluid outlet
835c and return line 607. As the working fluid leaves the reservoir
the first part 810 and second part 820 move towards each other and
directly engage by mechanical contact. The second arrangement 800b
shows the situation as the port 832 becomes aligned with the fluid
inlet 835b and just before the first part 810 and second part 820
move towards each other. The third arrangement 800c shows the
situation as enough working fluid has left the reservoir for the
first part 810 and second part 820 to directly engage by mechanical
contact.
[0086] The corresponding location of the second arrangement 800b
and the third arrangement 800b is shown on the valve timing
diagrams of FIGS. 22 and FIGS. 23, respectively. As can be seen, a
lost motion event occurs as the first part 810 and second part 820
move towards each other. During this event, the intake camshaft 110
continues to rotate but the intake valve 515 is held at a
substantially fixed lift position for a given crank angle degrees.
The length of the period may be determined by the spool valve 850.
For example, the spool valve 850 may be partially opened to
restrict a flow of the working fluid though the spool valve
850.
[0087] FIG. 21d shows a fourth arrangement 800d of the motion
controller 800 whereby the intake valve 515 is raised to a position
of maximum lift as shown in the diagram of FIG. 23. Although the
position of maximum lift, in terms of crank angle degrees (i.e. the
timing), is the same as the reference timing 1110, the amount of
maximum lift of the intake valve 515 is reduced by the motion
controller 800. This produces a downward shift in the intake valve
515 timing diagram, as shown in FIG. 24.
[0088] As the intake camshaft 111 continues to rotate, an interface
between the first part 810 and second part 820 which is where the
port 832 formally existed, is moved towards the fluid inlet 831, as
shown in the fifth arrangement 800e of FIG. 21e. Since the working
fluid is pumped by the pump through the non-return valve 860 and
fluid inlet 831, the pressure of the working fluid forces the first
part 810 and the second part 820 to separate by the working fluid
filling the port 832. At this point, the first part 810 and the
second part 820 move away from each other. The spring S encourages
the separation because the spring S acts on the inside of the first
part 810 and the second part 820 to naturally forces the first part
810 and the second part 820 apart. The separation of the first part
810 and the second part 820 is shown in the sixth arrangement 800f
of FIG. 21f.
[0089] It will be appreciated that when the intake camshaft 111
comprises the two raised profiles 113b, 113c, as shown in FIG. 16,
the intake valve 515 is closed in the fifth arrangement 800e of
FIG. 21e despite the lifter remaining on the raised profile 113c.
The intake valve 515 remains closed as the first part 810 and the
second part 820 move apart and the lifter returns to the base
circle 113a of the camshaft. It will further be appreciated that
the intake valve 115 closes earlier in the scenario indicated with
respect to FIGS. 21 to FIGS. 24 (which may be referred to as Early
Intake Valve Closing (EIVC) than it does in the scenario indicated
with respect to FIGS. 17 to FIGS. 18 (which may be referred to as
Late Intake Valve Closing (LIVC).
[0090] Although the intake camshaft 111 may comprise the two raised
profiles 113b, 113c, as shown in FIG. 16, the second profile 113c
is not able to lift the intake valve 515 due to the relative
movement of the first part 810 and second part 820 shown between
the second arrangement 800b and the third arrangement 800c. When
the two raised profiles 113b, 113c are used, the period between the
fifth arrangement 800e and the sixth arrangement 800f corresponds
to the smaller, second raised profile 113c. However, given that the
intake valve 515 closes at the fifth arrangement 800e, the effect
of the second raised profile 113c is not transferred to the intake
valve 515.
[0091] FIG. 25 shows a schematic illustration of components of an
internal combustion engine 1300. The internal combustion engine
1300 is a compression ignition engine suitable for diesel fuel. The
engine comprises six cylinders 1301-6. The engine 1300 comprises an
engine brake system that functions to release compression gas on
the compression stroke, that is when the piston moves between BDC
and TDC. As shown in the timing diagram of FIG. 26, the compression
release begins a few degrees before top dead centre (bTDC) with a
maximum valve lift after top dead centre (aTDC). The release of
compression gas from the cylinder reduces the force exerted on the
piston on the downward stroke by gas that is compressed in the
cylinder. This helps to assist a braking or retardation event.
[0092] As shown in FIG. 25, exhaust valve cams 1330 and intake
valve cams 1340 exist for each cylinder 1301-6. However, two-thirds
of the cylinders, i.e. four cylinders 1301-4 in this example,
comprise a two-stroke engine braking arrangement and one-third of
the cylinders, i.e. two cylinders 1305-6, comprise a single-stroke
or single-stroke engine braking arrangement. Various types of
two-stroke braking arrangements and one-stroke braking arrangements
are known per se that could be used in the system of FIG. 25.
Typically, a two-stroke braking arrangement acting on a cylinder
will provide greater braking power than will a one-stroke braking
arrangement acting on a cylinder. However, a two-stroke braking
arrangement typically comprises a greater number of components than
does a one-stroke braking arrangement and therefore is typically
more complicated, more expensive and occupies more space than a
one-stroke braking arrangement.
[0093] Systems such as the one illustrated in FIG. 25 which
comprises a single-stroke engine brake arrangement configured to
provide single stroke engine braking on at least one cylinder of
the plurality of cylinders and a two-stroke engine brake
arrangement configured to provide two-stroke engine braking on at
least one other cylinder of the plurality of cylinders are
advantageous because the combination of a single-stroke engine
brake arrangement acting on one cylinder and a two-stroke braking
arrangement acting on another cylinder provide sufficient braking
power but such systems are less costly and more space efficient
than corresponding systems in which each cylinder is provided with
a two-stroke engine braking arrangement.
[0094] The specific system shown in FIG. 25 in which a two-stroke
braking arrangement is provided for each of cylinders 1 to 4 and a
one-stroke braking is arrangement is provided for each of cylinders
5 to 6 is particularly advantageous in this respect.
[0095] As shown in FIG. 25, two-stroke engine brake cams 1320 for
controlling the two-stroke engine brake arrangements and
single-stroke engine brake cams 1310 for controlling the
single-stroke engine brake arrangements exist on a single, common
camshaft 1350 in a case 1360. In this example, two other cams are
shown as fuel pump cams 1315.
[0096] FIG. 26 illustrates schematically a valve timing diagram
1400 of a two-stroke engine brake system according to an example. A
first bump 1401 exists prior to a second bump 1402. Both bumps
1401, 1402 form the exhaust valve timing. Each bump 1401, 1402
comprises a compression release event. In one engine cycle, that is
720 degrees of rotation of the crankshaft, two compression release
events occur for a two-stroke engine brake system, whereas for a
single-stroke engine brake system, one compression release event
occurs for 720 degrees of rotation of the crankshaft. The bump 1401
comprises a first section 1401a which is a brake gas recirculation
lift (i.e. when exhaust gas is recirculated back into the
cylinder), a first compression release lift 1401b (i.e. the first
compression release event of the cycle) and a re-breading lift
1401b. The bump 1402 represents a second compression release lift
(i.e. the second compression release event of the cycle). A
deactivated exhaust event T occurs when the exhaust valve is
closed. This is typically where the normal exhaust gases are
released by the exhaust valve. However, combustion does not occur
during an engine braking event. A stunted timing 1410 event of the
intake valve is shown. That is, late intake valve opening (LIVO) as
described in the examples above could be used to avoid the back
flow of air during the braking event.
[0097] FIG. 27 illustrates schematically a top view of a valve
train assembly 1500 according to an example. The valve assembly
1500 comprises an intake rocker arm assembly 1540, an exhaust
rocker arm assembly 1520 and an engine brake rocker arm assembly
1530 for controlling the valves of a given cylinder, for example,
one of cylinders one to four described with respect to FIG. 25
above. Each of the intake rocker arm assembly 1540 and the exhaust
rocker arm assembly 1520 acts on two valves. In that respect, the
intake rocker arm assembly 1540 and the exhaust rocker arm assembly
1520 may be part of the valve train assembly described above, see
for example FIG. 7 which can be controlled to perform any of the
appropriate EEVO, EIVC, LIVC functions described above. The engine
brake rocker arm assembly 1530 acts on a single one of the exhaust
valves and may be controlled to cause two-stroke engine braking as
described above. Also shown is a single, common camshaft 1510
comprising a LIVO controlling cam 1501, an EIVC and LIVC
controlling cam 1502, an EEVO controlling cam 1503, an exhaust
rocker arm deactivation cam 1504 and an engine brake controlling
cam 1505. The common camshaft 1510 may be electromechanically
actuated to control all of the variable valve lift functions for
example: EEVO, EIVC, LIVC, single-stroke and two-stroke engine
braking.
[0098] Referring now to FIGS. 28a to 28c, there is illustrated an
engine brake rocker arm assembly 1530 that can be used, for
example, as the engine brake rocker arm assembly in the valve train
assembly 1500, illustrated in FIG. 27.
[0099] As shown in FIG. 28a, the engine brake rocker arm assembly
1530 is mounted for rotatable movement about a rocker arm shaft
2000. At a first end 1530a, the engine brake rocker arm assembly
1530 contacts a push rod 2002 and, at a second end 1530b, the
engine brake rocker arm assembly 1530 is contactable with a valve
stem 2004 of an exhaust valve 2006. The exhaust valve 2006 is one
of a pair of exhaust valves (only the exhaust valve 2006 is
illustrated) supported in a valve bridge assembly 400, as
illustrated in FIG. 4. The engine brake rocker arm assembly 1530 is
contactable with the valve stem 2004 via an intermediary part 400a
of the valve bridge 400, which is moveable by the engine brake
rocker arm assembly 1530 relative to the valve bridge assembly 400
as a whole.
[0100] The engine brake rocker arm assembly 1530 comprises at the
second end 1530b an engine brake control capsule 2008 (which is
illustrated in isolation in FIG. 28b) for selectively configuring
the engine brake rocker arm assembly 1530 in an engine brake OFF
configuration and an engine brake ON configuration.
[0101] The engine brake rocker arm assembly 1530 is configured in
the engine brake ON configuration when the engine is operating in
engine brake mode. When the engine is operating in engine brake
mode, as a camshaft rotates, for example the camshaft 1350
illustrated in FIG. 25, an engine brake cam arranged on the
camshaft 1350, for example one of the engine brake cams 1320 as are
also illustrated in FIG. 25, and which is in direct or indirect
contact with the push rod 2002, causes the push rod 2002 to move in
sympathy with the cam profile of the engine brake cam 1320. This
movement of the push rod 2002 causes the engine brake rocker arm
assembly 1530 to pivot about the rocker arm shaft 2000 and the
engine brake rocker arm assembly 1530 in turn causes the exhaust
valve 2006 to lift to cause an engine brake event. The cam profile
of the engine brake cam 1320 may, for example, be shaped so as to
cause the exhaust valve 2006 to perform the two-stroke engine brake
event illustrated in FIG. 26.
[0102] The engine brake rocker arm assembly 1530 is configured in
the engine brake OFF configuration when the engine is operating in
normal drive mode. In the engine brake OFF configuration, the
movement of the push rod 2002 caused by the cam profile of the
engine brake cam 1320 is absorbed as a lost motion stroke by the
engine brake control capsule 2008 so that the engine brake rocker
arm assembly 1530 does not transfer any movement to the exhaust
valve 2006.
[0103] As is known in the art, the engine brake control capsule
2008 may be of the type that comprises a first body 2008a and a
second body 2008b each comprising a circular end portion that is
crenulated around its length and which end portions face each
other. One of the bodies 2008a, 2008b is rotatable about it
longitudinal axis relative to the other of the bodies 2008a, 2008b
between a first position and a second position to configure the
engine brake control capsule 2008 in the engine brake OFF
configuration or the engine brake ON configuration.
[0104] When the engine brake control capsule 2008 is in the engine
brake ON configuration the raised portions of each of the
crenulated circular end portions face each other such that the
first body 2008a and the second body 2008b act as a single unit and
transfer the movement of the engine brake rocker arm assembly 1530
to the exhaust valve 2006 by means of a member 2009. When the
engine brake control capsule 2008 is in the engine brake OFF
configuration the crenulated circular end portions are positioned
so that every raised portion faces a recessed portion so that the
first body 2008a is moveable relative to the second body 2008b to
absorb the movement of the engine brake rocker arm assembly 1530 as
a lost motion stroke so that no movement is transferred to the
exhaust valve 2006 via the member 2009. The engine brake control
capsule 2008 comprises a lost motion spring 2010 for biasing the
first body 2008a and the second body 2008b away from each
other.
[0105] The engine brake rocker arm assembly 1530 further comprises
an actuator 2012 (shown separately in FIG. 28c) mounted on the side
of the brake rocker arm assembly 1530 for configuring the engine
brake control capsule 2008 in the engine brake ON and OFF
configurations. For clarity, the actuator 2012 is not shown in FIG.
28a but it should be appreciated that its longitudinal axis lies
along the dashed line shown in FIG. 28a. The actuator 2012
comprises a two-piece piston arrangement 2014 comprising a first
piston piece 2016 having a first end 2016a slidably arranged within
a first end 2018a of a second piston piece 2018.
[0106] An engine brake actuation cam 2022 is provided on a control
camshaft 2024 which is rotatable 180 degrees between a first
position and a second position to act on a second end 2016b of the
first piston piece 2016 to drive the two-piece piston arrangement
2014 linearly to cause rotation of one of the first 2008a and
second 2008b bodies, for example, the first body 2008a, relative to
the other of the first 2008a and second 2008b bodies, for example,
the second body 2008b, to configure the engine brake control
capsule 2008 between the engine brake ON and OFF configurations.
That is to say, when the actuation cam 2022 is rotated in a first
sense, the two-piece piston arrangement 2014 is driven linearly in
a first direction to cause rotation of one of the first 2008a and
second 2008b bodies relative to the other of the bodies in a first
sense to configure the brake control capsule 2008 in one of the ON
and OFF configurations. And then, when the actuation cam 2022 is
rotated back in the opposite sense, the two-piece piston
arrangement 2014 is driven linearly back in the opposite direction
to cause rotation of one of the first 2008a and second 2008b bodies
relative to the other of the bodies in the opposite sense to
configure the brake control capsule 2008 back into the other of the
ON and OFF configurations. In the example shown in FIG. 28c, the
actuator 2012 is shown in engine brake OFF position and hence is
driven linearly, when the actuation cam 2022 rotates, to the engine
brake ON position.
[0107] The control camshaft 2024 may be operated in any suitable
way, for example, by pressurised oil, pneumatically, or
electromechanically.
[0108] The two-piece piston arrangement 2014 is provided with a
threaded region 2026 arranged circumferentially around a section of
its outer surface and which cooperates with a threaded region of
one of the first 2008a and second 2008b bodies, in this example the
first body 2008a, to rotate that body between the engine brake ON
and OFF configurations when the two-piece piston arrangement 2014
is driven linearly. The two-piece piston arrangement 2014 is
provided with a return spring 2020 for biasing the two-piece piston
arrangement 2014 to a return position (in this example engine brake
OFF position) and also a compliance spring 2028 arranged between
the first piston piece 2016 and the second piston piece 2018. The
compliance spring 2028 is much stiffer than is the return spring
2020 and is arranged to bias the actuator 2012 to configure the
engine brake control capsule 2008 in the engine brake ON
configuration. In some scenarios, the control cam 2022 will rotate
but the rotatable one of the first 2008a and second bodies is not
in a condition to rotate. This causes the compliance spring 2028 to
be compressed by the first piston piece 2016 and once the rotatable
one of the first 2008a and second bodies is in a condition to
rotate, the compliance spring 2028 will extend and the actuator
2012 will configure the engine brake control capsule 2008 in the
engine brake ON configuration.
[0109] The engine brake control capsule 2008 may also function as a
mechanical lash adjuster.
[0110] Although for clarity it is not shown in FIG. 28a, it should
be appreciated that there is an exhaust rocker arm, for example,
one arranged like the rocker arm 300 in FIG. 4 for acting on the
exhaust bridge 400 during the normal engine drive mode to cause a
normal exhaust event lift of the exhaust valves carried by the
bridge 400 in response to the rotation of an exhaust cam, for
example cam 120 shown in FIG. 4. When the engine is drive mode the
exhaust rocker arm 300 is active and the engine brake rocker arm is
de-active and vice versa when the engine is in engine brake
mode.
[0111] Suitable means is provided for activating and deactivating
the exhaust rocker arm. For example, the exhaust rocker arm 300 may
be provided with a similar control capsule and actuator to that
illustrated in FIG. 28b and FIG. 28c in the rear section of the
exhaust rocker arm, i.e. the section that interfaces with the push
rod 200.
[0112] Preferably, a control cam (not shown) for controlling the
control capsule in the exhaust rocker arm is mounted on a common
shaft 2024 as the control cam 2022 for controlling the engine brake
control capsule 2008. In this way the common shaft 2024 can be used
to control the engine brake control capsule 2008 to configure it
into the engine brake ON configuration and to control the exhaust
rocker arm control capsule to configure it into the exhaust rocker
arm de-active configuration and can be used to control the engine
brake control capsule 2008 to configure it into the engine brake
OFF configuration and to control the exhaust rocker arm control
capsule to configure it into the exhaust rocker arm active
configuration.
[0113] When the engine is in normal drive mode there will be
periods when the exhaust rocker arm has moved the exhaust valve
bridge 400 out of contact with the exhaust brake rocker arm
assembly 1530. A suitable arrangement is provided in order to
maintain the connection between the exhaust brake rocker arm 1530
and the exhaust brake cam (e.g. via push rod 2002 in the example of
FIG. 30a) under load. In the example shown in FIG. 28a, the
arrangement comprises a fixed support element 1540 and a spring
1542 arranged between the exhaust brake rocker arm 1530 and the
fixed support element 1540 which biases the exhaust brake rocker
arm 1530 towards the exhaust brake cam (not shown in FIG. 28a).
[0114] Referring now to FIG. 29 there is illustrated a rocker arm
arrangement 2500 that can be configured to provide a normal exhaust
valve lift in normal engine drive mode and an exhaust brake valve
lift in exhaust brake mode.
[0115] At a first end, the rocker arm arrangement 2500 comprises a
first member 2502 for engagement with a push rod (not shown) that
is in contact with a rotating exhaust cam (not shown). The first
member 2502 may also function as a mechanical lash adjuster. At a
second end, the rocker arm arrangement 2500 comprises an exhaust
brake control capsule 2504 and associated actuator (not shown) that
are similar to those described above with reference to FIG. 28.
Also, at the second end, the rocker arm arrangement 2500 comprises
a second member 2506 for engagement with a valve bridge (not shown)
carrying a pair of exhaust valves (not shown). A lost motion spring
2508 is housed above the second member 2506. As described above
with respect to FIG. 28, the exhaust brake control capsule 2504 can
act upon one of the exhaust valves (not shown) carried by the valve
bridge (not shown).
[0116] In operation, the rocker arm arrangement 2500 pivots in
accordance with the cam profile (not shown) of the cam (not shown)
that acts on the push rod (not shown) that acts in turn on the
first member 2502. In normal engine drive mode, the exhaust brake
control capsule 2504 is in the engine brake OFF configuration and
provides no effect. In normal engine drive mode, the rocker arm
arrangement 2500 pivots through a lost motion stroke X before
contacting the second member 2506 to cause the second member 2506
to move the valve bridge (not shown) and hence both exhaust valves
(not shown) to provide a normal exhaust valve lift in accordance
with the cam profile (not shown) of the exhaust cam (not
shown).
[0117] In exhaust brake mode, the exhaust brake control capsule
2504 is in the engine brake ON configuration to provide an exhaust
brake event. In this mode, as the rocker arm arrangement 2500
pivots the control capsule 2504 causes the exhaust valve (not
shown) it acts upon to open first while the rocker arm arrangement
2500 pivots through the lost motion stroke X to contact the second
member 2506 to cause the valve bridge (not shown) to then open the
second exhaust valve (not shown). Following the engine rocker
arrangement 2500 contacting the second member 2506, the lift of
both of the exhaust valves (not shown) is controlled by the second
member 2506 in accordance with cam profile (not shown) of the
exhaust cam (not shown). The cam profile (not shown) may, for
example, provide a single stroke-exhaust lift and the arrangement
may be used on cylinders 5 and 6 in the system of FIG. 25.
[0118] It is to be understood that any feature described in
relation to any one example may be used alone, or in combination
with other features described, and may also be used in combination
with one or more features of any other of the examples, or any
combination of any other of the examples.
[0119] According to a first example, a cam phasing mechanism is
provided. The cam phasing mechanism for a cam assembly of an
internal combustion engine, the cam assembly comprising a camshaft
and an actuator for opening a valve at a reference position of
rotation of the camshaft. Aspects of the cam phasing mechanism are
as follows: [0120] Aspect 1: The cam phasing mechanism
comprises:
[0121] a force transfer member for interposition between the
camshaft and the actuator of the cam assembly for transferring
force between the camshaft and the actuator; and
[0122] an adjuster for selectively moving the force transfer member
to adjust the reference position of rotation of the camshaft.
[0123] Aspect 2: The cam phasing mechanism according to Aspect 1 of
the first example, wherein the adjuster comprises a first member
and a second member, wherein the first member is moveable relative
to the second member for selectively moving the force transfer
member relative to the second member to adjust the reference
position of rotation of the camshaft. [0124] Aspect 3: The cam
phasing mechanism according Aspect 2 of the first example, wherein
the first member is continuously moveable relative to the second
member for continuously adjusting the reference position of
rotation of the camshaft within a predetermined range. [0125]
Aspect 4: The cam phasing mechanism according to Aspect 2 or Aspect
3 of the first example, wherein the force transfer member is spaced
from the first member by a third member. [0126] Aspect 5: The cam
phasing mechanism according to Aspect 4 of the first example,
wherein the third member is pivotable about the first member.
[0127] Aspect 6: The cam phasing mechanism according to Aspect 4 or
Aspect 5 of the first example, wherein the third member is Y-shaped
such that a distal portion of the third member is a bifurcated
portion to enclose the force transfer member. [0128] Aspect 7: The
cam phasing mechanism according to any one of Aspect 2 to Aspects 6
of the first example, comprising a driving member for driving the
second member of the adjuster. [0129] Aspect 8: The cam phasing
mechanism according to Aspect 7 of the first example, wherein an
axis of rotation of the driving member is perpendicular to an axis
of rotation of the second member. [0130] Aspect 9: The cam phasing
mechanism according to any preceding Aspect of the first example,
wherein the first member is moveable relative to the second member
by translational motion of the first member. [0131] Aspect 10: The
cam phasing mechanism according to any preceding Aspect of the
first example, wherein the force transfer member comprises a first
roller for engagement with the camshaft of the cam assembly and a
second roller for engagement with the actuator of the cam assembly.
[0132] Aspect 11: The cam phasing mechanism according to Aspect 10
of the first example, wherein the first roller and the second
roller are each independently rotatable about a third roller.
[0133] Aspect 12: The cam phasing mechanism according to Aspect 10
or Aspect 11 of the first example, wherein the first roller and the
second roller are coaxial. [0134] Aspect 13: The cam phasing
mechanism according to Aspect 12 of the first example, wherein the
first roller and the second roller are rotatable about a common
axis, and wherein the first roller is restricted to a central
location along the common axis. [0135] Aspect 14: The cam phasing
mechanism according to any one of Aspect 10 to Aspect 13 of the
first example, wherein the second roller comprises two rollers,
wherein one of the two rollers is arranged on one side of the first
roller and the other of the two rollers is arranged on another side
of the first roller.
[0136] According to a second example, a cam assembly for an
internal combustion engine and for controlling actuation of a valve
is provided. Aspects of the cam assembly are as follows: [0137]
Aspect 1: The cam assembly comprises:
[0138] a camshaft;
[0139] an actuator moveable by rotation of the camshaft for opening
the valve at a reference position of rotation of the camshaft;
and
[0140] a force transfer member interposed between the camshaft and
the actuator for transferring force between the camshaft and the
actuator;
[0141] wherein the force transfer member is selectively moveable by
an adjuster to adjust the reference position of rotation of the
camshaft. [0142] Aspect 2: The cam assembly according to Aspect 1
of the second example, wherein the force transfer member is
selectively moveable either side of a reference plane between an
axis of the camshaft and an axis of the actuator. [0143] Aspect 3:
The cam assembly according to Aspect 15 or Aspect 16 of the second
example, wherein the actuator comprises a first surface for
avoiding contact with the force transfer member and a second
surface for engaging the force transfer member. [0144] Aspect 4:
The cam assembly according to Aspect 17 of the second example,
wherein the force transfer member comprises a first roller for
engaging the camshaft and a second roller for engaging the second
surface of the actuator. [0145] Aspect 5: The cam assembly
according to Aspect 18 of the second example, wherein the first
roller comprises a diameter that is greater than a diameter of the
second roller.
[0146] According to a third example, a valve train assembly for an
internal combustion engine is provided. The valve train assembly
comprising an exhaust valve and the cam assembly according to any
one of Aspects 1 to 5 of the second example.
[0147] According to a fourth example, an actuation mechanism for
controlling actuation of a valve of an internal combustion engine
is provided. Aspects of the actuation mechanism are as follows:
[0148] Aspect 1: The actuation mechanism comprises:
[0149] a first actuator for controlling actuation of the valve when
the actuation mechanism is arranged in a first position; and
[0150] a second actuator for controlling actuation of the valve
when the actuation mechanism is arranged in a second position;
[0151] wherein the first actuator and second actuator are moveable
relative each other. [0152] Aspect 2: The actuation mechanism
according to Aspect 1 of the fourth example, wherein movement of
the first actuator is governed by a first driver and movement of
the second actuator is governed by a second driver that is
different to the first driver. [0153] Aspect 3: The actuation
mechanism according to Aspect 2 of the fourth example, wherein the
first driver comprises a mechanical force and the second driver
comprises a hydraulic force. [0154] Aspect 4: The actuation
mechanism according to any preceding Aspect of the fourth example,
comprising an engagement area for mechanical engagement with a
rocker arm assembly to move a rocker atm of the rocker arm
assembly, wherein the engagement area comprises a portion of the
first actuator and a portion of the second actuator when the
actuation mechanism is arranged in the second position. [0155]
Aspect 5: The actuation mechanism according to Aspect 4 of the
fourth example wherein, the first actuator comprises a slave part
and a master part that are separable from each other and the
engagement area comprises a portion of the slave part of the first
actuator and the portion of the second actuator and wherein the
second actuator acts to maintain the valve at a substantially fixed
position as the master part separates from the slave part to
arrange the actuation mechanism in a third position. [0156] Aspect
6: The actuation mechanism according to Aspect 5 of the fourth
example, wherein the slave part and the master part that are
separated by a gap when the actuation mechanism is arranged in the
third position. [0157] Aspect 7: The actuation mechanism according
to Aspect 6 of the fourth example, wherein the gap is variable when
the actuation mechanism is arranged between the third position and
a fourth position. [0158] Aspect 8: The actuation mechanism
according to any one of Aspect 5 to Aspect 7 of the fourth example,
wherein the actuation mechanism comprises a pressure release
portion for releasing fluid pressure from a working zone acting on
the second actuator of the actuation mechanism to enable the second
actuator and the slave part of the first actuator to move the
actuation mechanism from the third position into the fourth
position in which the valve is closed and the slave part and the
master part of the first actuator are non-separated. [0159] Aspect
9: The actuation mechanism according to any preceding Aspect of the
fourth example, comprising a fluid passageway comprising a fluid
inlet, a working zone and a fluid outlet; wherein a volume of fluid
within the working zone is variable by movement of fluid between
the fluid inlet and fluid outlet. [0160] Aspect 10: The actuation
mechanism according to any preceding Aspect of the fourth example,
comprising a controller for hydraulically controlling movement of
the second actuator. [0161] Aspect 11: The actuation mechanism
according to Aspect 10 of the fourth example, wherein the
controller controls release of fluid from the fluid outlet to
reduce the volume of fluid within the working zone. [0162] Aspect
12: The actuation mechanism according to any preceding Aspect of
the fourth example, wherein the first actuator is moveable within
the second actuator.
[0163] According to a fifth example, a valve train assembly for an
internal combustion engine is provided. The valve train assembly
comprising an exhaust valve and the actuation mechanism according
to any one of Aspects 1 to 12 of the fourth example for actuating
the exhaust valve.
[0164] According to a sixth example, an actuation assembly for an
internal combustion engine is provided. Aspects of the actuation
assembly are as follows: [0165] Aspect 1: The actuation assembly
comprises:
[0166] an actuation mechanism according to any one of Aspect 1 to
Aspect 12 of the fourth example for controlling actuation of an
exhaust valve; and
[0167] a motion controller for controlling actuation of an intake
valve;
[0168] wherein the motion controller comprises a pressure release
portion for releasing fluid pressure from a working zone acting on
the second actuator of the actuation mechanism. [0169] Aspect 2:
The actuation assembly according to Aspect 1 of the sixth example,
wherein the pressure release portion is activatable by an intake
camshaft. [0170] Aspect 3: The actuation assembly according to
Aspect 15 of the sixth example, wherein the pressure release
portion is independent of the opening timing of the exhaust valve.
[0171] Aspect 4: The actuation assembly according to Aspect 15 or
Aspect 16 of the sixth example, wherein the pressure release
portion is a channel for communication between a fluid outlet of
the actuation mechanism and a return line of a hydraulic circuit.
[0172] Aspect 5: The actuation assembly according to any one of
Aspect 14 to Aspect 17 of the sixth example, wherein the pressure
release portion is configured to release pressure from the working
zone between 0.5 and 0.7 mm of lift of the exhaust valve.
[0173] According to a seventh example, a motion controller for
controlling movement of a valve of an internal combustion engine is
provided. Aspects of the motion controller are as follows: [0174]
Aspect 1: The motion controller comprises:
[0175] a first part for engagement with a rocker arm assembly;
and
[0176] a second part for engagement with a camshaft;
[0177] wherein the motion controller is arrangeable between an
unlocked state and a locked state before the valve is opened;
[0178] wherein in the unlocked state the second part is moveable
towards the first part by the camshaft without imparting a lifting
force to the valve to thereby delay an opening of the valve. [0179]
Aspect 2: The motion controller according to Aspect 1 of the
seventh example wherein, after the second part has been moved a
pre-defined distance by the camshaft without imparting a lifting
force to the valve, the second part contacts the first part to
arrange the motion controller in the locked state wherein the first
part and the second part are moveable as a unit by the camshaft to
impart a lifting force to the valve. [0180] Aspect 3: The motion
controller according to Aspect 1 or Aspect 2 of the seventh
example, wherein a resistance to relative movement between the
first part and the second part in the unlocked state is provided by
a resilient member. [0181] Aspect 4: The motion controller
according any preceding Aspect of the seventh example, wherein the
first part and second part form a reservoir having a port
communicable with a fluid inlet and the motion controller comprises
a switch for switching the fluid inlet to a fluid outlet to release
fluid from the reservoir.
[0182] According to an eighth example, a valve train assembly for
an internal combustion engine is provided. Aspects of the valve
train assembly are as follows: [0183] Aspect 1: The valve train
assembly comprising an intake valve and the motion controller
according to any one of Aspects 1 to 4 of the seventh example for
actuating the intake valve. [0184] Aspect 2: The valve train
assembly according to Aspect 1 of the eight example, wherein a
raised profile of a camshaft is configured to move the motion
controller between the unlocked state and the locked state before
the intake valve is opened. [0185] Aspect 3: The valve train
assembly according to Aspect 2 of the eight example, wherein the
intake valve opens at a greater rate of lift than when a
corresponding rate of lift when the intake valve is closed.
[0186] According to a ninth example, an engine braking system for
an internal combustion engine comprising a plurality of engine
cylinders is provided. Aspects of the engine braking system are as
follows: [0187] Aspect 1: The engine braking system comprising a
single-stroke engine brake arrangement configured to provide single
stroke engine braking on at least one cylinder of the plurality of
cylinders and a two-stroke engine brake arrangement configured to
provide two-stroke engine braking on at least one other cylinder of
the plurality of cylinders. [0188] Aspect 2: An engine braking
system according to Aspect 1 of the ninth example wherein the
single-stroke engine brake arrangement is configured to provide
single-stroke engine braking on each of N.sub.1 cylinders of the
plurality of cylinders and the two-stroke engine brake arrangement
is configured to provide two-stroke engine braking on each of
N.sub.2 other cylinders of the plurality of cylinders and wherein
N.sub.1 is greater than N.sub.2. [0189] Aspect 3: An engine braking
system according to Aspect 2 of the ninth example where N.sub.1 is
a whole multiple of N.sub.2. [0190] Aspect 4: An engine braking
system according to Aspect 2 or Aspect 3 of the ninth example
wherein N.sub.1=4 and N.sub.2=2. [0191] Aspect 5: An engine braking
system according to Aspect 4 of the ninth example wherein the
internal combustion engine comprises 6 cylinders arranged in a
sequence and the single-stroke engine brake arrangement is
configured to provide single stroke engine braking on cylinders one
to four in the sequence and the two-stroke engine brake arrangement
is configured to provide two-stroke engine braking on cylinders
five to six in the sequence.
[0192] It is to be understood that any Aspect described in relation
to any one of the first to ninth examples may be used alone, or in
combination with other Aspects described, and may also be used in
combination with one or more Aspects of any other of the first to
ninth examples, or any combination of any other of the first to
ninth examples.
REFERENCE SIGNS LIST
[0193] 1 cam phasing mechanism [0194] 2a force transfer member
[0195] 2b adjuster [0196] 21 first roller [0197] 22 second roller
[0198] 23 third roller [0199] 3 third member [0200] 31 lever arm
[0201] 32 proximal portion [0202] 33 distal portion [0203] 4, 4',
2502 first member [0204] 41 fourth threaded portion [0205] 5, 2506
second member [0206] 51, 71, 81 locating member [0207] 52 second
threaded portion [0208] 53 third threaded portion [0209] 6, 6'
bearing [0210] 7, 124, 604, 770 housing [0211] 8, 1360 case [0212]
10 driving member [0213] 11 first threaded portion [0214] 100 cam
assembly [0215] 110, 120, 1350, 1510 camshaft [0216] 111, 121,
1501-5 cam [0217] 112a, 112b, 122 cam lobe [0218] 113a, 123a base
surface [0219] 113b, 123b, 113c raised profile [0220] 115, 125
camshaft axis [0221] 130, 2012 actuator [0222] 131 first surface
[0223] 132 second surface [0224] 135 axis of actuator [0225] 200,
210, 220, 2002 push rod [0226] 300, 310, 320, 1520, 1530, 1540
rocker arm assembly [0227] 311, 321 joint [0228] 312, 322 ball
[0229] 313, 323 socket [0230] 323a, 721 engagement face [0231] 400,
410, 420 valve bridge assembly [0232] 400a intermediary part [0233]
500, 510, 520, 1500 valve assembly [0234] 501, 511, 521, 2004 valve
stem [0235] 502, 512, 522 valve head [0236] 505, 515, 525 valve
[0237] 600 actuation assembly [0238] 601 accumulator [0239] 602,
603 supply line [0240] 605 accumulator piston [0241] 606, 607
return line [0242] 608 common passageway [0243] 610, 620 force
transmitter [0244] 700 actuation mechanism [0245] 700-1 first
position [0246] 700-2 second position [0247] 700-3 third position
[0248] 700-4 fourth position [0249] 704, 740, 840 engagement area
[0250] 705 damper [0251] 710 first actuator [0252] 710a slave part
[0253] 710b master part [0254] 720 second actuator [0255] 730, 830,
831, 835b fluid inlet [0256] 731 intermediate passageway [0257]
733, 833 working zone [0258] 734 reserve passageway [0259] 735,
835a., 835c fluid outlet [0260] 750, 850 spool valve [0261] 751,
851 rotating member [0262] 752, 852 sliding member [0263] 760, 860
non-return valve [0264] 761, 861 moveable part [0265] 762 base
[0266] 800 motion controller [0267] 800-1 unlocked state [0268]
800-2 locked state [0269] 800a first arrangement [0270] 800b second
arrangement [0271] 800c third arrangement [0272] 800d fourth
arrangement [0273] 800e fifth arrangement [0274] 800f sixth
arrangement [0275] 802 pressure release portion [0276] 810 first
part [0277] 811, 821 cavity [0278] 820 second part [0279] 832 port
[0280] 862 switch [0281] 1000, 2000 valve train assembly [0282]
1100, 1110, 1120 reference timing [0283] 1101 early phasing [0284]
1102 late phasing [0285] 1111, 1121 valve opening [0286] 1112, 1122
valve closing [0287] 1113, 1123 maximum lift [0288] 1200 elongated
timing [0289] 1210, 1410 stunted timing [0290] 1300 internal
combustion engine [0291] 1301--6 engine cylinder [0292] 1310
single-stroke engine brake cams [0293] 1315 fuel pump cams [0294]
1320 two-stroke engine brake cams [0295] 1330 exhaust valve cams
[0296] 1340 intake valve cams [0297] 1400 two-stroke engine brake
valve timing [0298] 1401 first bump [0299] 1402 second bump [0300]
1530 engine brake rocker arm assembly [0301] 1530a, 2016a, 2018a
first end [0302] 1530b, 2016b second end [0303] 1540 fixed support
element [0304] 1542 spring [0305] 2000 rocker arm shaft [0306] 2006
exhaust valve [0307] 2008 engine brake control capsule [0308] 2008a
first body [0309] 2008b second body [0310] 2009 member [0311] 2010,
2508 lost motion spring [0312] 2014 two-piece piston arrangement
[0313] 2016 first piston piece [0314] 2018 second piston piece
[0315] 2020 return spring [0316] 2022 engine brake actuation cam
[0317] 2024 control camshaft [0318] 2026 threaded region [0319]
2028 compliance spring [0320] 2500 rocker arm arrangement [0321]
2504 exhaust brake control capsule [0322] A roller assembly region
[0323] B first direction [0324] C reciprocation path [0325] D
second direction [0326] E1, E2 region of overlap [0327] F valve
phasing range [0328] G gap [0329] H valve closing direction [0330]
J valve opening direction [0331] K, Q lost motion region [0332] L
translation axis [0333] M1, M2, M3 motion axis [0334] N abutment
area [0335] P reference plane [0336] R1, R2, R3 rotation direction
[0337] S spring [0338] S1 first side [0339] S2 second side [0340] T
deactivated exhaust event [0341] X lost motion stroke
* * * * *