U.S. patent application number 15/126294 was filed with the patent office on 2017-03-23 for valve train assembly.
The applicant listed for this patent is Eaton SRL. Invention is credited to Jiri Novotny.
Application Number | 20170081996 15/126294 |
Document ID | / |
Family ID | 50635003 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170081996 |
Kind Code |
A1 |
Novotny; Jiri |
March 23, 2017 |
VALVE TRAIN ASSEMBLY
Abstract
A valve train assembly has at least a camshaft with at least a
first cam body and a second cam body, each axially movable over the
camshaft between a first axial position and a second axial position
and each earn body being provided with a first cam for controlling
a valve in the first axial position and a second cam for
controlling the valve in the second axial position; and one or more
couplers for coupling the movement of the cam bodies. A first
groove extends along a part of the circumference of the first cam
body. A second groove extends along a part of the circumference of
the second cam body, An engager for engaging alternately the first.
and second groove is included, such that either the first cam body
is moved to the first axial position or the second cam body is
moved to the second axial position.
Inventors: |
Novotny; Jiri; (Prague,
CZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eaton SRL |
Torino |
|
IT |
|
|
Family ID: |
50635003 |
Appl. No.: |
15/126294 |
Filed: |
March 17, 2015 |
PCT Filed: |
March 17, 2015 |
PCT NO: |
PCT/EP2015/055507 |
371 Date: |
September 15, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01L 2013/0052 20130101;
F01L 13/0036 20130101 |
International
Class: |
F01L 13/00 20060101
F01L013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2014 |
GB |
1404874.8 |
Claims
1: A valve train assembly comprising: a camshaft including a first
cam body and a second cam body, each cam body being axially movable
over the camshaft between a first axial position and a second axial
position, and each cam body including a first cam configured to
control a valve in the first axial position and a second cam
configured to control the valve in the second axial position; a
coupler configured to couple a movement of the first cam body and
the second cam body; a first groove extending along a part of a
circumference of the first cam body; a second groove extending
along a part of a circumference of the second cam body; and an
engager configured to alternately engage the first and second
groove, such that either the first cam body is moved to the first
axial position or the second cam body is moved to the second axial
position.
2: The assembly of claim 1, wherein the engager includes a first
movable pin configured to engage in the first groove and a second
movable pin configured to engage in the second groove.
3: The assembly of claim 2, wherein the engager further includes a
solenoid connected to each movable pin, wherein the solenoid is
configured to move a respective movable pin into engagement with
the respective groove.
4: The assembly of claim 1, wherein the first groove includes, in
rotation direction, an axial direction component towards a side of
the second axial position, and wherein the second groove includes,
in rotation direction, an axial direction component towards a side
of the first axial position
5: The assembly of claim 4, wherein the first groove is
mirror-symmetrical to the second groove.
6: The assembly of claim 1, wherein the first cam body and second
cam body are substantially cylindrical.
7. The assembly of claim 6, wherein the cam bodies include an axial
groove, and wherein the cam shaft includes a corresponding axial
rib.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. national stage application under
35 U.S.C. .sctn.371 of International Application No.
PCT/EP2015/055507, filed on Mar. 17, 2015, and claims benefit to
British Patent Application No. 1404874.8, filed on Mar. 18, 2014.
The International Application was published in English on Sep. 24,
2015, as WO 2015/140137 A1 under PCT Article 21(2).
FIELD
[0002] The invention relates to a valve train assembly including at
least a camshaft with at least a first cam body and a second cam
body.
BACKGROUND
[0003] A valve train assembly is used for an internal combustion
engine and has typically at least some of the following elements:
valves, rocker arms, push-rods, lifters and camshaft.
[0004] Depending on the type of valve train assembly some or all of
the elements of a valve train assembly. For example an internal
combustion engine having the camshaft in the engine block, there
will also be present push-rods and rocker arms, while with an
overhead camshaft, the cams on the camshaft will be in direct
contact with the lifters or tappets, which move the valves in the
cylinder head.
[0005] It is known to use variable valve timing or variable valve
lifting to change the characteristics of an combustion engine, such
that performance, emission of the engine or fuel economy is
improved.
[0006] A system to achieve this is known as cam shifting. In such a
system at least two cams are provided on a cam body for each valve.
The two cams have a different profile, such that the timing is
different depending on the cam used for the respective valve. By
shifting the cam body in axial direction over the camshaft, one can
select which cam is used to control the respective valve.
[0007] With such a system it is also possible to put a cylinder in
a deactivated mode, by choosing a cam profile for the valves of the
cylinders, which keep the valves closed at all time and use
compressed air as a spring.
[0008] The valve train assembly according to the preamble is for
example known from US2010/0251982. According to this publication, a
cam body is provided with cams for two valves of a cylinder. The
cam body is also provided with two oppositely curved grooves on the
portion between the cams for the two valves. Two solenoid driven
pins are also provided, which pins can be engaged with their
respective two grooves. When a pin is brought into engagement with
the respective groove, the engaged pin, in combination with the
rotation of the cam shaft, will push the cam body to a first
position in which one of the two cams are used for controlling the
valves. By engaging the other pin into the respective groove, the
cam body is pushed to another position, in which the other cams are
used for controlling the valves.
[0009] The space on the cam body between the cams for the two
valves is limited. The grooves and the solenoid driven pins have to
be arranged within this limited space, causing severe limitations
on the design of the grooves and the solenoid driven pins.
[0010] Furthermore, according to this art, each cylinder should be
provided with a cam body for the exhaust cam shaft and a cam body
for the intake cam shaft, each cam body being provided with grooves
and solenoid driven pins. This makes the valve train assembly
complex and prone to malfunctions.
SUMMARY
[0011] An aspect of the invention provides a valve train assembly,
comprising: a camshaft including a first cam body and a second cam
body, each cam body being axially movable over the camshaft between
a first axial position and a second axial position, and each cam
body including a first cam configured to control a valve in the
first axial position and a second cam configured to control the
valve in the second axial position; a coupler configured to couple
a movement of the first cam body and the second cam body; a first
groove extending along a part of a circumference of the first cam
body; a second groove extending along a part of a circumference of
the second cam body; and an engager configured to alternately
engage the first and second groove, such that either the first cam
body is moved to the first axial position or the second cam body is
moved to the second axial position.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present invention will be described in even greater
detail below based on the exemplary figures. The invention is not
limited to the exemplary embodiments. All features described and/or
illustrated herein can be used alone or combined in different
combinations in embodiments of the invention. The features and
advantages of various embodiments of the present invention will
become apparent by reading the following detailed description with
reference to the attached drawings which illustrate the
following:
[0013] FIG. 1 shows a perspective view of part of an embodiment of
the valve train assembly according to the invention;
[0014] FIG. 2 shows a cross sectional view of the embodiment of
FIG. 1;
[0015] FIG. 3 shows a top view of cylinder head with the embodiment
of the valve train assembly according to FIG. 1; and
[0016] FIG. 4 shows a second perspective view of part of the
embodiment of the valve train assembly according to FIG. 1.
DETAILED DESCRIPTION
[0017] An aspect of the invention provides a valve train assembly
in which the above mentioned disadvantages are reduced or even
removed.
[0018] The invention relates to a valve train assembly comprising:
at least a camshaft with at least a first cam body and a second cam
body, each axially movable over the camshaft between a first axial
position and a second axial position and each cam body being
provided with a first cam for controlling a valve in the first
axial position and a second cam for controlling the valve in the
second axial position; and coupling means for coupling the movement
of the first cam body and the second cam body
[0019] An aspect of the invention provides a valve train which is
characterized by [0020] a first groove extending along a part of
the circumference of the first cam body; [0021] a second groove
extending along a part of the circumference of the second cam body;
and [0022] engagement means for engaging alternately the first and
second groove, such that either the first cam body is moved to the
first axial position or the second cam body is moved to the second
axial position.
[0023] With the valve train assembly according to an aspect the
invention the first and second groove are arranged on separate cam
bodies, which are coupled together. So, if for example the first
groove on the first cam body is engaged and the first cam body is
moved to the first axial position, it will also take along the
second cam body due to the coupling means.
[0024] When the second groove is engaged on the second cam body,
the second cam body will be moved to the second position and take
along the first cam body due to the coupling means.
[0025] As a result, the space available on a cam body can be
dedicated to a single groove with single engagement means, opposite
to the prior art, in which the space available on a cam body was
needed for at least two grooves and two engagement means.
[0026] With the valve train assembly according to the invention, it
is even possible to use a third cam body with a third groove
coupled to the other two cam bodies, such that a three position
axial displacement of the cam bodies is possible. Depending on the
number of cylinders in the combustion engine, the number of coupled
cam bodies can even be further expanded.
[0027] Preferably, the engagement means comprise a first movable
pin for engagement in the first groove and a second movable pin for
engagement in the second groove. A pin is a simple means to be used
for engagement with a groove. The rotation of the cam shaft in
combination with the engagement of the groove ensures, that the cam
body is moved to the desired position.
[0028] In a preferred embodiment of the valve train assembly
according to the invention the engagement means further comprise a
solenoid connected to each movable pin for moving the pin into
engagement with the respective groove. By using the pin as the core
of the solenoid a very compact actuation of the pin can be
achieved. Using a permanent magnet solenoid and a ramp at the end
of each groove, the solenoid needs to be powered only shortly, to
bring the pin into engagement with the groove. The permanent magnet
of the solenoid will keep the pin, until the pin is pushed back by
the ramp at the end of the groove.
[0029] In a further preferred embodiment of the valve train
assembly according to the invention the first groove has in
rotation direction an axial direction component towards the side of
the second axial position and wherein the second groove has in
rotation direction an axial direction component towards the side of
the first axial position.
[0030] Because of the combined action of the engagement of the pin
in the respective groove and the rotation of the cam shaft and thus
the cam body, the cam body will be moved towards the desired
position.
[0031] Preferably, the first groove is mirror-symmetrical to the
second groove. This ensures that the acceleration and deceleration
of the cam body, when one of the grooves is engaged is the same,
which will contribute to a smooth-running engine.
[0032] In yet another embodiment of the valve train assembly
according to the invention the first cam body and second cam body
are substantially cylindrical.
[0033] Preferably, the substantially cylindrical cam bodies
comprise at least an axial groove and wherein the cam shaft is
provided with at least a corresponding axial rib.
[0034] FIG. 1 shows a perspective view of part of an embodiment of
the valve train assembly 1 according to the invention.
[0035] The valve train assembly 1 has camshaft 2 with a cam body 3.
This cam body 3 is substantially cylindrical and axially slidable
over the cam shaft 2. To ensure, that the cam body 3 is rotated
along with the cam shaft 2, axial ribs 4 are arranged on the
camshaft 2 and corresponding grooves 5 are arranged in the
cylindrical cam body 3.
[0036] The cam body 3 is provided on both sides with cam lobes 6,
7. The center part of the cam body 3 is provided with a curved
groove 8, which extends along a part of the circumference of the
center part of the cam body 3. Due to the curved shape, the groove
8 has also an axial direction component.
[0037] A solenoid 9 operated pin 10 is provided in the wall of a
cylinder head 11 and can engage with the groove 8. When the
solenoid 9 is powered and the operating pin 10 engages with the
groove 8, the cam body 3 will be moved in the direction of the
arrow D as a result of the rotation in the direction of the arrow R
of the cam shaft 2 and the cam body 3.
[0038] The valve train assembly 1 is furthermore provided with
rocker arms 12, which are each at one end provided with a cam
follower 13, which follows the profile of the cam lobes 6, 7. The
other end 14 of the cam follower 13 is in contact with the tip of a
valve stem 15, such that the valve 15 is controlled by the cam 6,
7.
[0039] In the shown position, the cam follower 13, follows the
profile of the cam 6, 7. If the cam body is moved in axial
direction D, then the cam follower 13, will be moving of the
surface of the cam body 3, just next to the cam lobes 6, 7. As the
cam body 3 is substantially cylindrical, the valve 15 will in this
position not be operated and the corresponding cylinder will be
deactivated. As shown in FIG. 4, it is also possible to arrange a
second cam lobe 28, 29 next to the cam lobes 6, 7, with a different
profile, such that behavior of the valve movement can be
altered.
[0040] FIG. 3 shows a top view of cylinder head with the embodiment
of the valve train assembly 1 according to FIG. 1. The cylinder
head shown is typically part of a 6-cylinder combustion engine.
[0041] The valve train assembly 1 has the cam shaft 2, which is
typically used for operating the exhaust valves 15 and a second cam
shaft 16 for operating the intake valves.
[0042] Both cam shafts 2, 16 are provided with a number of cam
bodies 3, 17, 18, 19, 20, 21. On the cam shaft 2, the cam body 3 is
provided with the groove and the cam body 18 is provided with a
mirror-symmetrical groove 22. This groove 22 can be engaged by
engagement means 23. When engaged, the groove 22 will cause the cam
body 18 to move in the opposite direction of the arrow D.
[0043] The cam bodies 3 and 18 are coupled via forks 24, 26
connected via a connection rod 25 (see FIG. 4). When the cam body 3
is moved in the direction D, the forks 24, 26 and connection rod 25
will take the cam body 18 along. On the other hand, when the cam
body 18 is moved in the opposite direction by engagement of the
groove 22, the cam body 3 will be taken along. In this way it is
possible to move the cam bodies 3, 18 between two positions.
[0044] As the other cam bodies 17 cannot be moved at the same time
as the cam bodies 3, 18 due to the timing of the valves of the
different cylinders, a separate mechanism 27 is provided on the
connection rod 25, such that the movement of the cam bodies 17 is
delayed with respect to the cam bodies 3, 18. Such mechanisms are
already known in the prior art.
[0045] While the invention has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. It will be understood that changes and
modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below. Additionally,
statements made herein characterizing the invention refer to an
embodiment of the invention and not necessarily all
embodiments.
[0046] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B, and C"
should be interpreted as one or more of a group of elements
consisting of A, B, and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B, and C,
regardless of whether A, B, and C are related as categories or
otherwise. Moreover, the recitation of "A, B, and/or C" or "at
least one of A, B, or C" should be interpreted as including any
singular entity from the listed elements, e.g., A, any subset from
the listed elements, e.g., A and B, or the entire list of elements
A, B, and C.
* * * * *