U.S. patent application number 10/666864 was filed with the patent office on 2005-03-24 for engine lubrication system and pressure reducing valve for limiting overhead oil flow.
Invention is credited to Plenzler, Jeremy M., Zheng, Liyun.
Application Number | 20050061290 10/666864 |
Document ID | / |
Family ID | 34194784 |
Filed Date | 2005-03-24 |
United States Patent
Application |
20050061290 |
Kind Code |
A1 |
Plenzler, Jeremy M. ; et
al. |
March 24, 2005 |
ENGINE LUBRICATION SYSTEM AND PRESSURE REDUCING VALVE FOR LIMITING
OVERHEAD OIL FLOW
Abstract
A lubrication system for an internal combustion engine having a
pressure reducing valve to optimize oil flow through an engine to
increase engine efficiency. The lubrication system includes an
engine driven oil pump connected to supply pressurized oil through
a main oil feed to a main bearing gallery, a cam gallery and a
hydraulically actuated device such as a cam phaser or switching
valve lifters. A pressure reducing valve connected between the main
bearing feed restricts oil flow to the cam gallery to raise oil
pressure supplied to the hydraulically actuated device. The
increased oil pressure to the hydraulically actuated device allows
the engine to use a smaller oil pump and thereby increase engine
efficiency while providing for actuation of the cam phaser or the
switching lifters over the full engine speed range.
Inventors: |
Plenzler, Jeremy M.; (Royal
Oak, MI) ; Zheng, Liyun; (Troy, MI) |
Correspondence
Address: |
LESLIE C. HODGES
General Motors Corporation
Legal Staff, Mail Code 482-C23-B21
P.O. Box 300
Detroit
MI
48265-3000
US
|
Family ID: |
34194784 |
Appl. No.: |
10/666864 |
Filed: |
September 18, 2003 |
Current U.S.
Class: |
123/196M ;
184/6.5 |
Current CPC
Class: |
F01L 1/34 20130101; F01M
1/16 20130101; F01M 11/02 20130101; F01L 13/0005 20130101; F01M
1/02 20130101 |
Class at
Publication: |
123/196.00M ;
184/006.5 |
International
Class: |
F01M 001/04 |
Claims
1. A lubrication system for an internal combustion engine, the
system comprising: an oil pump driven by the engine and supplying
pressurized oil through a main oil feed to a main bearing gallery,
a cam gallery, and a hydraulically actuated device; and a pressure
reducing valve connected between the pump and the cam gallery and
operative to selectively limit oil flow to the cam gallery and
thereby raise oil pressure supplied to the main bearing gallery and
hydraulically actuated device to a desired operating level greater
than the oil pressure supplied to the cam gallery.
2. A system as in claim 1 wherein the hydraulically actuated device
is a cam phaser.
3. A system as in claim 1 wherein the hydraulically actuated device
is a series of switching lifters.
4. A system as in claim 1 wherein the hydraulically actuated device
is a stepping valve train.
5. A system as in claim 2 wherein the pressure reducing valve
includes an open orifice limiting oil flow to the cam gallery to
maintain a desired minimum oil pressure to the main bearing gallery
and cam phaser at lower engine speeds.
6. A system as in claim 2 wherein the pressure reducing valve
maintains adequate cam phaser oil pressure during engine
operation.
7. A system as in claim 2 wherein the pressure reducing valve
increases oil pressure to the cam phaser as engine speed
increases.
8. A system as in claim 1 wherein the cam gallery receives oil from
the main bearing gallery.
9. A system as in claim 1 including an oil pickup connected with an
inlet of the pump to draw in oil from an engine oil pan.
10. A system as in claim 1 including an oil filter connected
between the outlet of the oil pump and the main oil feed.
11. A system as in claim 1 wherein the pressure reducing valve
maintains a constant oil pressure in the cam gallery during engine
operation.
Description
TECHNICAL FIELD
[0001] This invention relates to engine oil systems and, more
particularly, to a system including a pressure reducing valve to
optimize oil flow and pressure for various lubrication and
actuation functions.
BACKGROUND OF THE INVENTION
[0002] Internal combustion engines may use lubricating oil for many
purposes including for example, lubricating moving parts, actuating
cam phasers, and controlling switching valve lifters for valve
stepping and cylinder deactivation. Cam phasers and cylinder
deactivation devices generally require a higher oil pressure for
actuation during engine operation than the moving parts of the
engine require for proper lubrication. Switching lifters generally
require high oil pressure for high lift operation and a lower oil
pressure for low lift operation.
[0003] Since engines having cam phasers or cylinder deactivation
devices generally require higher than normal oil pressure for their
operation, while other components which do not require high
pressure lubrication, such as a valvetrain components, can be over
lubricated. Since valve trains commonly require a relatively low
oil pressure to provide adequate lubrication to prevent engine
wear, a method of reducing oil pressure to an engine's valve train
is desired to reduce overall oil flow and increase engine
efficiency.
SUMMARY OF THE INVENTION
[0004] Co-pending applications pertaining to related subject matter
were filed concurrently with this application on ______, 2003 as
U.S. application Ser. No. ______ (GP-302777), U.S. application Ser.
No. ______ (GP-303044), and U.S. application Ser. No. ______
(GP-303046).
[0005] The present invention provides an oil system for an internal
combustion engine having a pressure reducing valve to optimize oil
pressures in the engine while increasing engine efficiency by
minimizing parasitic losses created from over lubrication.
[0006] In an exemplary embodiment, the oil system includes an oil
pump having an inlet and an outlet. An oil pickup connected with
the inlet extends into an engine oil sump to draw oil into the oil
system. The outlet of the oil pump connects to a main oil feed
which supplies oil to a main bearing gallery and a hydraulically
actuated device such as a cam phaser or switching lifters. Oil sent
to the cam phaser is used to actuate the cam phaser, while oil
directed to the main bearing gallery is used primarily for
lubrication purposes. When switching lifters are present, some of
the oil directed to the cam phaser is diverted to a control, which
supplies oil pressure to the switching lifters to allow valve
stepping or cylinder deactivation. In addition, some of the oil
pumped into the main bearing gallery is sent through a cam gallery
feed to a cam gallery in an upper part of the engine for
lubrication of a valve train.
[0007] A pressure reducing valve connected between the main bearing
gallery and the cam gallery acts as a flow restrictor that
selectively limits oil flow to the cam gallery. The pressure
reducing valve includes an orifice to limit oil flow into the cam
gallery under low oil pressure conditions. During high oil pressure
conditions, the flow restrictor partially closes outlet openings to
maintain a constant oil pressure in the cam gallery.
[0008] The restriction of oil flow to the cam gallery created by
the valve forms back pressure before the valve which increases oil
pressure in the main feed. The increased oil pressure within the
main feed is then available for operating the hydraulically
actuated device. As a result, the oil pressure to the hydraulically
actuated device and the main bearing gallery is increased while the
rest of the oil system operates at a lower oil pressure. This
allows cam phasing or cylinder deactivation at engine idle or other
conditions when oil pump pressure would otherwise be too low to
actuate the cam phaser or the switching lifters. The increased oil
pressure supplied to the hydraulically actuated device allows the
device to be operated at all engine speeds without a large increase
in the size of the oil pump. The use of a smaller oil pump reduces
parasitic losses for increased engine efficiency.
[0009] These and other features and advantages of the invention
will be more fully understood from the following description of
certain specific embodiments of the invention taken together with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a pictorial view of an internal combustion engine
including an oil system with a cam phaser according to the
invention;
[0011] FIG. 2 is a pictorial view of a portion of a direct acting
valve train with switching lifters having portions broken away to
show interior features of the components;
[0012] FIG. 3 is a pictorial view of an exemplary oil system for
the engine of FIG. 1; and
[0013] FIG. 4 is a pictorial view of a pressure reducing valve for
the oil system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] Referring now to FIG. 1 of the drawings in detail, numeral
10 generally indicates an internal combustion engine. The engine
includes a cylinder block 12 having a bank of cylinders 14
containing pistons 16 connected with a crankshaft 18. A cylinder
head 20 carries intake and exhaust valves 21, 22 actuated by
camshafts 24, 26. A cam phaser 28 is mounted on the exhaust
camshaft 26 to vary the exhaust valve timing. An oil pan 30 below
the block forms an oil sump for the engine.
[0015] FIG. 2 illustrates an exhaust portion of an engine valve
train 32 for use in an overhead cam piston type engine. The valve
train 32 includes exhaust camshaft 26 which is driven through a
drive sprocket 34 connected by a chain 36 (FIG. 1) with the engine
crankshaft 18. Cam phaser 28 is connected between the sprocket 34
and the camshaft 26 in order to vary the timing of the camshaft
relative to the piston motion and other operating functions of the
engine and relative to other camshafts of the engine.
[0016] The exhaust valves 22 are actuated through switching valve
lifters 38 which are engaged by cams 40 of the camshaft 26. The
switching valve lifters 38 react to oil pressure to deactivate or
selectively change the amount of valve lift provided for the
associated exhaust valves 22. A controller 42 receives oil pressure
and distributes or cuts off the control pressure to the switching
lifters 38 to actuate the valve train 32. The controller 42 may
supply oil pressure to the switching lifters 38 to reduce valve
lift or disable valve lift for cylinder deactivation.
[0017] FIG. 3 illustrates the passages of an oil system 44 within
the engine 10. The oil system includes an engine driven oil pump 46
having an inlet 48 and an outlet 50. An oil pickup 52 connected
with the pump 46 extends into the sump of the oil pan 30. The pump
46 connects through an oil filter 54 with a main oil feed 56. The
main oil feed 56 distributes oil to a cam phaser feed 58 and a main
bearing gallery 60. The main bearing gallery 60 supplies oil to
crankshaft main bearings and connecting rod bearings, not shown.
The main bearing gallery 60 connects a cam gallery feed 62 which
carries oil to a cam gallery 64 for lubricating camshaft bearings
and valve gear 66 within the cylinder head 20 of the engine 10.
[0018] In accordance with the invention, a pressure reducing valve
68, as shown in FIG. 4 is, connected between the main bearing
gallery 60 and the cam gallery 64. The pressure reducing valve 68
has a tubular housing 70 surrounding a slidable flow control piston
72. The piston 72 internally defines an orifice 74. A biasing
spring 76 between the piston 72 and an outlet end 78 of the housing
70 urges the piston 72 toward an inlet end 80 of the housing having
a large inlet opening 82. A plurality of outlet openings 84 extend
through a tubular wall of the housing 70 adjacent the outlet end
78.
[0019] During engine operation, the oil pump 46 draws oil from the
oil pan 30 through the oil pickup 52. The oil is then pumped
through the pump outlet 50 and oil filter 54 to the main oil feed
56. The oil in the main oil feed 56 is then directed to the main
bearing gallery 60 and the cam phaser 28. Some of the oil in the
main bearing gallery 60 flows to the cam gallery 64 through the
pressure reducing valve 68.
[0020] Under low oil pressure conditions, the biasing spring 76
holds the flow control piston 72 against the inlet end 80 of the
housing 70, opening the outlet openings 84 to allow oil to flow
through the pressure reducing valve 68. Thus, oil flow from the
main bearing gallery 60 passes through the piston orifice 74 into
the outlet end 78 of the housing 70 and through the outlet openings
84 to the cam gallery 64.
[0021] As oil pressure increases at the inlet end 80 of the housing
70, the piston 72 begins to slide toward the outlet end 78 and
compress the biasing spring 76. As the piston 72 moves toward the
outlet end 78, the piston restricts access to the outlet openings
84 to maintain constant oil pressure to the cam gallery 64. As oil
pressure on the inlet end 80 of the housing 70 is reduced, the
biasing spring 76 pushes the piston 72 back toward the inlet end 80
to open the outlet openings 84 and maintain constant oil pressure
to the cam gallery 64.
[0022] At lower engine speeds while oil pump output is minimal,
only a small portion of the oil pumped though the oil system 44
flows through the orifice 74 of the pressure reducing valve 68. The
remainder of the oil not flowing through the orifice 74 builds oil
pressure on the inlet end 80 of the pressure reducing valve 68
which creates back pressure in the main bearing gallery 60 and in
turn increases oil pressure to main oil feed 56 and the cam phaser
28. This allows the cam phaser 28 to actuate during idle and low
rpm conditions, when oil pump pressure would otherwise be too low
for cam phaser actuation.
[0023] As engine speed increases, the output from the oil pump 34
increases, causing the oil pressure in the system 32 to increase.
As oil pressure increases at the inlet end 68, the piston 60 slides
toward the outlet end 66 against the biasing spring 64. The
movement of the piston 60 restricts flow through the pressure
reducing valve 56 by closing the outlet openings 72. The
restriction of oil to flow through the pressure reducing valve 56
maintains a lower oil pressure in the cam gallery than in the
remainder of the system. The restriction of oil flow to the cam
gallery 64 limits the system's oil flow requirements, thereby
allowing the engine 10 to operate with a smaller more efficient oil
pump.
[0024] While the invention has been described by reference to
certain preferred embodiments, it should be understood that
numerous changes could be made within the spirit and scope of the
inventive concepts described. Accordingly, it is intended that the
invention not be limited to the disclosed embodiments, but that it
have the full scope permitted by the language of the following
claims.
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