U.S. patent application number 10/833682 was filed with the patent office on 2004-11-04 for internal combustion engine.
Invention is credited to Lancefield, Timothy Mark, Owen, Richard Alwyn.
Application Number | 20040216710 10/833682 |
Document ID | / |
Family ID | 32982441 |
Filed Date | 2004-11-04 |
United States Patent
Application |
20040216710 |
Kind Code |
A1 |
Owen, Richard Alwyn ; et
al. |
November 4, 2004 |
Internal combustion engine
Abstract
An engine is described having a camshaft 14 formed with an oil
passage 26, a cover 22 fitted to the front of the engine and
overlying the front end of the camshaft 14, and an oil supply line
24 formed in the engine front cover. The camshaft 14 is formed with
an axially projecting extension that is rotatably and sealingly
received in an opening formed in the front cover 22 to enable the
oil passage 26 in the camshaft to communicate with the oil supply
line 24 in the engine cover 22.
Inventors: |
Owen, Richard Alwyn;
(Banbury, GB) ; Lancefield, Timothy Mark;
(Shipston on Stour, GB) |
Correspondence
Address: |
SMITH-HILL AND BEDELL
12670 N W BARNES ROAD
SUITE 104
PORTLAND
OR
97229
|
Family ID: |
32982441 |
Appl. No.: |
10/833682 |
Filed: |
April 27, 2004 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 1/34 20130101; F01L
1/3442 20130101; F01L 1/02 20130101; F01L 1/022 20130101; F01L
1/047 20130101; F01L 1/46 20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 29, 2003 |
GB |
0309710.2 |
Claims
1. An engine having a camshaft formed with an oil passage, a cover
fitted to the front of the engine and overlying the front end of
the camshaft, and an oil supply line formed in the engine front
cover, wherein the camshaft is formed with an axially projecting
extension that is rotatably and sealingly received in an opening
formed in the front cover to enable the oil passage in the camshaft
to communicate with the oil supply line in the engine cover.
2. An engine as claimed in claim 1, wherein the camshaft is fitted
with a variable valve timing mechanism actuated by means of the oil
in the oil passage.
3. An engine as claimed in claim 2, wherein the variable valve
timing mechanism is a vane-type phaser.
Description
[0001] The present invention relates to an internal combustion
engine.
[0002] The optimum angles at which the inlet and exhaust valves of
an internal combustion engine should open and close, both in
relation to one another and in relation to the engine crankshaft,
and optimum valve lift all vary with the engine speed and load
conditions. In an engine with fixed camshafts, a compromise setting
must be adopted in which the different performance parameters are
traded off one against the other.
[0003] To achieve performance improvements over a range of engine
speeds and loads, it has already been proposed to vary the cam
phase, duration, lift or a combination of these parameters in
relation to the crankshaft by the introduction of variable valve
actuation mechanisms.
[0004] Several variable valve actuation mechanisms are known from
the prior art each having its own advantages and disadvantages. The
majority of these mechanisms use oil pressure to control their
operation via a control valve to which the oil is supplied by way
of passages in the camshaft and/or the cylinder head. A problem
that is encountered with this approach is that the rate at which
oil can be supplied to the control valve is restricted by the size
of the passages. Furthermore, there will be a drop in oil pressure
due to the cylinder head being far removed from the oil pump in the
case of many engines. Consequently, the variable valve actuation
mechanism can only respond slowly when a change to its current
setting is required.
[0005] A still further disadvantage is that the requirement for oil
passages in the engine block, cylinder head and valve train can
make it difficult to retro-fit a variable valve actuation mechanism
into an existing engine.
[0006] U.S. Pat. No. 6,247,436 discloses an internal combustion
engine having a crankshaft and a camshaft the ends of which project
from a front end of the engine, a hydraulically operable variable
valve actuation mechanism at the front end of the engine for
driving the camshaft, an engine driven oil pump located at the
front end of the engine and drive means located at the front end of
the engine for transmitting torque from the crankshaft to the
variable valve actuation mechanism. A front cover overlying the
variable valve actuation mechanism comprises oil supply passages
that are directly connected to the variable valve actuation
mechanism, to enable the resistance to oil flow of the hydraulic
circuit connecting the engine drive oil pump to the variable valve
actuation mechanism to be reduced.
[0007] U.S. patent application Ser. No. 2002/0029910 also shows a
camshaft that is fitted with a vane-type phaser, i.e. a phase
changing mechanism, to which oil is supplied through a cover fitted
to the front of the engine.
[0008] In both these prior art proposals, a spigot projecting from
the engine front cover fits inside part of the phaser or the
camshaft to supply oil to the phaser. Such a configuration
necessarily increases the diameter of at least part of the phaser
and in the case of the phaser described in U.S. patent application
Ser. No. 2002/0029910, this spigots extends most of the way into
the phaser and forces the diameter of the entire assembly to be
increased.
[0009] With a view to mitigating this problem, the present
invention provides an engine having a camshaft formed with an oil
passage, a cover fitted to the front of the engine and overlying
the front end of the camshaft, and an oil supply line formed in the
engine front cover, wherein the camshaft is formed with an axially
projecting extension that is rotatably and sealingly received in an
opening formed in the front cover to enable the oil passage in the
camshaft to communicate with the oil supply line in the engine
cover.
[0010] In the invention, the camshaft is extended forwards to
project into the front cover instead of there being a spigot on the
front cover that projects into the camshaft. In this way, the
desired fluid communication between the oil supply line of the
front cover and the oil passage of the camshaft is achieved without
the need to increase the diameter of any part of the camshaft or
the phaser.
[0011] The invention will now be described further, by way of
example, with reference to the accompanying drawing, which is a
partial section through a camshaft fitted with a vane-type
phaser.
[0012] The accompanying drawing shows a camshaft 14 coupled to a
drive pulley 16 through a vane-type phaser having vanes 18 and vane
cavities 20. The pulley 16 has inwardly extending vanes 18 each of
which extends into a respective arcuate recess defined by the
camshaft 14 and divides the recess into two variable volume
cavities 20 or working chambers. Torque is transmitted from the
pulley 16 to the camshaft 16 through oil filling the cavities 20.
When no oil can flow into or out of the cavities, the pulley 16 and
the camshaft 14 are hydraulically locked to one another. To vary
the angular position of the pulley 14 relative to the camshaft and
thereby effect a change in the phase of the camshaft 14 relative to
the engine crankshaft that drives the pulley 16, oil is admitted
into the cavity on one side of a vane while at the same time
allowing oil to escape from the cavity on the opposite side of the
vane.
[0013] A camshaft having this type of phaser is more fully
described in U.S. Pat. No. 2002/0059910, which is imported herein
by reference. FIG. 4 of the latter patent application shows a
similar section to that shown in the accompanying drawing. For this
reason, it is not deemed necessary to describe the camshaft 14 nor
the vane-type phaser in greater detail within the present context.
It is also not necessary to dwell on the construction and operation
of a vane-type phaser because it is not fundamental to the present
invention. The invention is concerned with the manner of
introducing oil into a rotating camshaft rather than with the
function served by the oil after it has been so introduced.
[0014] The engine of the present invention is fitted with a front
cover 22 having various oil supply lines 24 that communicate
through a control valve (not shown) with main oil supply and return
galleries that lead to the engine oil pump. The supply lines 24 in
turn communicate with various passages 26 that lead to different
ones of the vane cavities 20. A suitable engine front cover is
described fully in U.S. Pat. No. 6,247,436, which is imported
herein by reference and for this reason it is not deemed necessary
for it to be described in detail within the present context.
[0015] The camshaft 14 and the front cover 22 shown in the
accompanying drawings differ from the prior art designs in that the
camshaft 14 has an end that projects axially beyond the phaser and
is received in an opening in the front cover 12. The end of the
camshaft 14 can rotate within the front cover 22 and continuous
communication between the passages 26 and the supply lines 24 is
achieved through radial bores 32 in the camshaft and
circumferentially extending grooves 34 in the wall of the
cylindrical opening. The shaft is further provided with seals 30
that seal against the lands defined between the grooves in the
opening.
[0016] Because no part of the cover 22 extends into the camshaft,
the diameter of the camshaft 14 and of the phaser need not be
increased to allow a rotary hydraulic connection to be achieved
between the camshaft and the engine front cover.
[0017] In this way, the invention permits a phaser to be contained
within a pulley having the same size as a conventional camshaft
drive pulley and no modification is required to the engine block to
provide an adequate oil supply to the phaser other than to fit a
front cover to the engine block, as has been proposed
previously.
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