U.S. patent application number 13/802323 was filed with the patent office on 2014-09-18 for active pressure relief valve system and method.
This patent application is currently assigned to Honda Motor Co., Ltd.. The applicant listed for this patent is HONDA MOTOR CO., LTD.. Invention is credited to Kevin Danford.
Application Number | 20140261280 13/802323 |
Document ID | / |
Family ID | 51521689 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140261280 |
Kind Code |
A1 |
Danford; Kevin |
September 18, 2014 |
ACTIVE PRESSURE RELIEF VALVE SYSTEM AND METHOD
Abstract
An active pressure relief valve system and method for
lubricating an internal combustion engine includes a reservoir, a
pump for pumping fluid from the reservoir through the internal
combustion engine, and an active relief valve fluidly disposed
downstream from the pump for both variably adjusting pressure of
the fluid within the internal combustion engine and limiting the
pressure of the fluid within the internal combustion engine to a
maximum pressure threshold. The active relief valve is configured
to variably and electronically adjust the pressure of the fluid
within the internal combustion engine when commanded by a
controller, and further configured to mechanically limit the
pressure of the fluid within the internal combustion engine to a
maximum pressure threshold.
Inventors: |
Danford; Kevin; (Dublin,
OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HONDA MOTOR CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
Honda Motor Co., Ltd.
Tokyo
JP
|
Family ID: |
51521689 |
Appl. No.: |
13/802323 |
Filed: |
March 13, 2013 |
Current U.S.
Class: |
123/188.9 ;
123/198R |
Current CPC
Class: |
F01M 1/20 20130101 |
Class at
Publication: |
123/188.9 ;
123/198.R |
International
Class: |
F01M 11/00 20060101
F01M011/00 |
Claims
1. An active pressure relief valve system for lubricating an
internal combustion engine, comprising: a reservoir; a pump for
pumping fluid from the reservoir through the internal combustion
engine; and an active relief valve fluidly disposed downstream from
the pump for both variably adjusting pressure of the fluid within
the internal combustion engine and limiting the pressure of the
fluid within the internal combustion engine to a maximum pressure
threshold, the active relief valve configured to variably and
electronically adjust the pressure of the fluid within the internal
combustion engine when commanded by a controller and further
configured to mechanically limit the pressure of the fluid within
the internal combustion engine to the maximum pressure
threshold.
2. The active pressure relief valve system of claim 1 wherein the
active relief valve includes: an actuator that variably and
electronically adjusts the pressure of the fluid within the
internal combustion engine via rotational movement; and a piston
movable against urging of a spring that mechanically limits the
pressure of the fluid within the internal combustion engine via
axial movement.
3. The active pressure relief valve system of claim 2 wherein the
active relief valve is disposed within only a single relief bore
defined within the internal combustion engine.
4. The active pressure relief valve system of claim 2 wherein the
piston includes at least one axial throughole and the active relief
valve includes a rotatable member variably and rotatably movable
between a first position and a second position for variably opening
or closing the at least one axial throughole, the first position
allowing relatively more fluid flow through the at least one axial
throughole than the second position.
5. The active pressure relief valve system of claim 4 wherein the
actuator is a motor that rotatably moves the rotatable member under
command by the controller.
6. The active pressure relief valve system of claim 5 wherein the
rotatable member is connected to the motor by the spring such that
rotation of the spring by the motor causes rotation of the
rotatable member relative to the piston.
7. The active pressure relief valve system of claim 6 wherein one
of the piston and a wall of the internal combustion engine defining
a relief bore in which the active relief valve is disposed includes
a protrusion and the other of the piston and the wall includes an
aperture in which the protrusion is received to prevent relative
rotation between the wall and the piston.
8. The active pressure relief valve system of claim 4 wherein the
motor includes a torsion spring that urges the rotatable member
toward the second position such that, when the controller is not
commanding the pressure relief valve, the rotatable member moves
toward the second position.
9. The active pressure relief valve system of claim 1 further
including: the controller that commands the active relief valve to
variably adjust the pressure of the fluid within the internal
combustion engine; and a pressure sensor operatively connected to
the controller that senses the pressure of the fluid and sends a
signal to the controller that is indicative of the pressure sensed,
and wherein the controller variably adjusts the pressure of the
fluid based on the signal from the pressure sensor.
10. The active pressure relief valve system of claim 1 further
including: a relief bore defined in the internal combustion engine
in which the active relief valve is received; a first discharge
passage fluidly connected to the relief bore for discharging the
fluid passing through the relief valve to variably adjust the
pressure of the fluid of the internal combustion engine; and a
second discharge passage fluidly connected to the relief bore for
discharging the fluid passing through the relief valve to limit the
pressure of the fluid in the internal combustion engine to the
maximum pressure threshold.
11. The active pressure relief valve system of claim 1 wherein an
indicator is operatively connected to the controller, the indicator
activated when there is a failure of the active relief valve.
12. An active oil pressure relief valve for a vehicle, comprising:
a valve assembly disposed within a relief bore, the relief bore
fluidly connected downstream to a pump for pumping fluid from a
reservoir and arranged to selectively return the fluid to the
reservoir to variably control a pressure of the fluid and to limit
a maximum pressure of the fluid; an actuator of the valve assembly
rotatably movable to variably control the pressure of the fluid;
and a piston of the valve assembly axially movable to limit the
maximum pressure of the fluid, the piston axially displaced when
the fluid reaches the maximum pressure and thereby passing through
the valve assembly back to the reservoir.
13. The active pressure relief valve of claim 12 wherein the valve
assembly includes a spring for urging the piston toward a closed
position, the piston movable axially against the urging of the
spring when the pressure of the fluid reaches the maximum
pressure.
14. The active pressure relief valve of claim 13 wherein the valve
assembly includes a rotatable member that is rotatable by the
actuator for selectively opening and closing at least one passage
defined through the piston, and wherein a degree of rotation of the
rotatable member by the actuator corresponds to a degree of closure
of the at least one passage by the rotatable member.
15. The active pressure relief valve of claim 14 wherein the piston
includes a radial wall portion through which the at least one
passage is defined and a cylindrical sleeve wall portion depending
from the radial wall portion, and wherein the rotatable member is
cooperatively received radially and axially within the cylindrical
sleeve wall portion.
16. The active pressure relief valve of claim 14 wherein the at
least one passage is a plurality of axial througholes defined
through the piston and the rotatable member includes a
corresponding plurality of axial througholes defined therethrough,
the rotatable member rotatable by the actuator from a first
rotatable position wherein the plurality of axial througholes and
the corresponding plurality of axial througholes are misaligned to
inhibit flow through the at least one passage and a second
rotatable position wherein the plurality of axial througholes and
the corresponding plurality of axial througholes are in registry
with one another.
17. The active pressure relief valve of claim 13 wherein the
actuator is a motor having an output shaft connected to the
rotatable member by the spring for transferring rotation movement
of the output shaft to the rotatable member.
18. The active pressure relief valve of claim 12 further including
a controller operatively connected to the actuator for control
thereof based on a sensed pressure of the fluid.
19. An active pressure relief valve method for lubricating an
internal combustion engine, comprising: providing an active relief
valve fluidly disposed downstream from a pump fluidly connected to
a fluid reservoir for both variably adjusting pressure of a fluid
pumped by the pump within the internal combustion engine and
limiting the pressure of the fluid within the internal combustion
engine to a maximum pressure threshold; variably and electronically
adjusting the pressure of the fluid within the internal combustion
engine via a controller operatively connected to the active relief
valve; and passively and mechanically limiting the pressure of the
fluid within the internal combustion engine to a maximum pressure
threshold.
20. The method of claim 19 wherein variably and electronically
adjusting the pressure of the fluid includes controlling an
actuator to rotatably move the active relief valve, and passively
and mechanically limiting the pressure of the fluid includes urging
a piston via a spring toward a closed position for inhibiting
passage of the fluid until the pressure reaches the maximum
pressure threshold.
Description
BACKGROUND
[0001] Conventional vehicles typically use mechanical oil pumps to
provide the necessary oil flow and pressure for internal combustion
engine operation and durability. For example, in one arrangement, a
single gerotor mechanical pump is permanently driven by the
internal combustion engine's crank shaft. Some vehicle
manufacturers have begun to introduce advanced mechanical oil pump
designs, including variable displacement in an attempt to reduce
the power consumption of the pump associated with unnecessarily
high engine supply oil pressure. The relief systems associated with
conventional oil pumps typically employ a single or double stage
mechanical relief system to reduce the pumping losses of the
mechanical pump. One known design employs a single electric
solenoid valve in addition to a standard mechanical relief valve.
This allows control of the single electric solenoid valve by a
controller (e.g., providing an additional bypass) to increase
engine efficiency through reduction of oil pump pressure pumping
losses.
[0002] Power consumption in a gerotor-style mechanical oil pump is
comprised of two main components: mechanical friction and pumping
friction. The mechanical friction of the pump is generally
determined by pump component materials, manufacturing precision,
and other physical pump-related variables. The mechanical friction
of the oil pump can usually only be reduced by changing the
physical design of the pump, and results in a constant friction
(i.e., power loss) value across varying pump outlet pressures for a
given engine/pump speed. The pumping friction of the mechanical
pump increases linearly with output pressure for a given engine
speed. As the oil pressure necessary for complete operation and
durability of the engine is not singularly a function of engine
speed, increases in engine efficiency can be realized through
adaptive control of engine oil pressure. The use of a mechanical
relief valve limits the adaptability of a relief function to
control through other mechanical engine characteristics, i.e.,
pressure, speed, temperature, etc. The operation of a mechanical
valve generally cannot adapt to complex real-time changes in engine
operation and oil pressure requirements.
[0003] Some vehicle manufacturers have begun to add additional
electric solenoid relief valves to oil systems to increase the
pressure adaption capability of the system. However, known
applications typically utilize small, dual position solenoid
valves, i.e., toggle-type valves with on or off operation. This
limits the capability of the relief valve to areas with large
pressure reduction potential and cannot be utilized to actively
modify the engine supply pressure under all conditions due to the
dual operation solenoid having a single size orifice. When the
valve is open, the orifice is an additional flow area that will act
to reduce the oil pump outlet pressure. An electric solenoid used
in conjunction with a standard mechanical relief valve will
increase the adaptability of the pressure supply system and
decrease the power consumption of the oil pump; however, without
active control over the effective size of the relief system
orifice, full adaptability and maximum oil pump efficiency cannot
be realized.
[0004] Current concerns with the application of a variable orifice
size pressure relief primarily concern packaging and cost. Known
proportional valves that will produce the required orifice area
range require large input torques to operate and induce significant
flow restrictions, even when open to the maximum orifice size.
Additionally, the added power consumption of the proportional valve
could offset the power consumption reduction of the pressure
reduction, rendering the system null from a power consumption and
efficiency standpoint. Powerful proportional valves that could
provide the required flow rate and pressure drop requirements tend
to be very large and heavy. From a packaging and fluid flow
standpoint, the physical space required also poses significant
problems.
SUMMARY
[0005] According to one aspect, an active pressure relief valve
system for lubricating an internal combustion engine includes a
reservoir, a pump for pumping fluid from the reservoir through the
internal combustion engine, and an active relief valve fluidly
disposed downstream from the pump for both variably adjusting
pressure of the fluid within the internal combustion engine and
limiting the pressure of the fluid within the internal combustion
engine to a maximum pressure threshold. The active relief valve is
configured to variably and electronically adjust the pressure of
the fluid within the internal combustion engine when commanded by a
controller, and further configured to mechanically limit the
pressure of the fluid within the internal combustion engine to the
maximum pressure threshold.
[0006] According to another aspect, an active oil pressure relief
valve for a vehicle includes a valve assembly disposed within a
relief bore. The relief bore is fluidly connected downstream to a
pump for pumping fluid from a reservoir and arranged to selectively
return the fluid to the reservoir to variably control the pressure
of the fluid and to limit a maximum pressure of the fluid. The
active oil pressure relief valve further includes an actuator of
the valve assembly rotatably movable to variably control the
pressure of the fluid and a piston of the valve assembly axially
movable to limit the maximum pressure of the fluid. The piston is
axially displaced when the fluid reaches the maximum pressure and
thereby passes through the valve assembly back to the
reservoir.
[0007] According to a further aspect, an active pressure relief
valve method for lubricating an internal combustion engine includes
providing an active relief valve fluidly disposed downstream from a
pump fluidly connected to a fluid reservoir for variably adjusting
pressure of a fluid pumped by the pump within the internal
combustion engine and limiting the pressure of the fluid within the
internal combustion engine to a maximum pressure threshold,
variably and electronically adjusting the pressure of the fluid
within the internal combustion engine via a controller operatively
connected to the active relief valve, and passively and
mechanically limiting the pressure of the fluid within the internal
combustion engine to a maximum pressure threshold.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic cross-sectional view of an active
pressure relief valve system according to an exemplary
embodiment.
[0009] FIG. 2 is a perspective view of an active pressure relief
valve of the active pressure relief valve system of FIG. 1.
[0010] FIG. 3 is an exploded perspective view of the active
pressure relief valve of FIG. 2.
[0011] FIG. 4 is a partial cross-sectional view showing the active
pressure relief valve both variably adjusted to a closed position
and mechanically held in a closed position.
[0012] FIG. 5 is a partial cross-sectional view of the active
pressure relief valve similar to FIG. 4 but showing the active
pressure relief valve variably adjusted to allow fluid flow
therethrough.
[0013] FIG. 6 is a partial cross-sectional view of the active
pressure relief valve similar to FIG. 4 but showing a piston of the
valve mechanically forced open against the urging of a spring.
[0014] FIG. 7 is a top view of the active pressure relief valve
showing apertures through the piston fully closed by a rotatable
member.
[0015] FIG. 8 is a view similar to FIG. 7 but showing the rotatable
member rotated to partially open the apertures for variably
adjusting pressure.
[0016] FIG. 9 is another view similar to FIG. 7 but showing the
rotatable member fully rotated so that corresponding apertures
therethrough are in registry with the apertures through the
piston.
DETAILED DESCRIPTION
[0017] Referring now to the drawings wherein the showings are for
purposes of illustrating one or more exemplary embodiments and not
for purposes of limiting same, FIG. 1 schematically illustrates an
active pressure relief valve system 10 for lubricating an internal
combustion engine 12 on an associated vehicle (not shown). The
active pressure relief valve system 10 includes a reservoir 14 of
fluid 16, such as oil, and a pump 18 for pumping the fluid 18 from
the reservoir 14 through the internal combustion engine 12. The
active pressure relief valve system 10 further includes an active
relief valve 20 (also referred to herein as an active oil pressure
relief valve for a vehicle) fluidly disposed downstream from the
pump 18 for both variably adjusting pressure of the fluid 16 within
the internal combustion engine 12 and limiting the pressure of the
fluid 16 within the internal combustion engine 12 to a maximum
pressure threshold. As described in more detail below, the active
relief valve 20 is configured to variably and electronically adjust
the pressure of the fluid 16 within the internal combustion engine
12 when commanded by a controller 22 and further configured to
mechanically limit the pressure of the fluid 16 within the internal
combustion engine 12 to the maximum pressure threshold. In the
illustrated embodiment of FIG. 1, the controller 22 is an
electronic control unit and can be the main electronic control unit
provided on the vehicle, though this is not required. Optionally, a
filter (not shown) may be fluidly downstream of the pump 18 and
upstream from the active relief valve 20.
[0018] With additional reference to FIGS. 2 and 3, the active
relief valve 20 of the illustrated embodiment includes a valve
assembly 30 disposed within a relief bore 32. The relief bore 32 is
fluidly connected to and arranged downstream from the pump 18. The
relief bore 32 is particularly arranged to allow the active relief
valve 20 to selectively return the fluid 16 pumped by the pump 18
to the reservoir 14 to variably control the pressure of the fluid
and to limit a maximum pressure of the fluid 16 within the internal
combustion engine 12. In the illustrated embodiment, the relief
bore 32 is fluidly connected to a main passage 34 defined through
the internal combustion engine 12 for diverting a portion of the
fluid 16 passing through the main passage 34 and returning the
fluid 16 to the reservoir 14 via the active relief valve 20. For
this purpose, the active relief valve 20 includes an actuator 36 of
the valve assembly 30 that is rotatably movable to variably control
the pressure of the fluid 16 and a piston 38 of the valve assembly
30 that is axially movable to limit the maximum pressure of the
fluid 16.
[0019] As shown, the valve assembly 30 can include a spring 40, in
addition to the actuator 36 and the piston 38, for urging the
piston 38 toward a closed position (the position of the piston 38
shown in FIGS. 4 and 5). The piston 38 is movable axially against
the urging of the spring 40 to an open position (the position of
the piston 38 shown in FIG. 6, for example) when the pressure of
the fluid 16 reaches or exceeds the maximum pressure. The spring 40
can be selected so that its spring characteristics (e.g., spring
coefficient) corresponds to the maximum pressure (i.e., the piston
38 is only movable to compress the spring 40 when the pressure
within the internal combustion engine 12 reaches or exceeds the
maximum pressure). In one embodiment, the spring 40 is selected so
that the maximum pressure is approximately 70 psi, though other
maximum pressures could be used as will be known and appreciated by
those skilled in the art.
[0020] In addition to the actuator 36, the piston 38 and the spring
40, the valve assembly 30 can further include a rotatable member 44
that is rotatable by the actuator 36 for variably adjusting
pressure within the internal combustion engine 12. As will be
described in more detail below, the actuator 36 variably and
electronically adjusts the pressure of the fluid 16 within the
internal combustion engine 12 via rotational movement of the
rotatable member 44 and the piston 38 is movable against urging of
the spring 40 to mechanically limit the pressure of the fluid 16
within the internal combustion engine 12 via axial movement. The
piston 38 is axially displaced when the fluid 16 reaches (or
exceeds) the maximum pressure and thereby passes through the valve
assembly 30 back to the reservoir 14. In an exemplary embodiment,
the actuator 36 is a motor that rotatably moves the rotatable
member 44 under command by the controller 22 to variably change a
cross-sectional opening through the active relief valve 20 to
thereby variably adjust fluid pressure within the internal
combustion engine 12.
[0021] More specifically, the piston 38 can include at least
passage therethrough partially defined by at least one axial
throughole. In the illustrated embodiment, the at least one axial
throughole is a plurality of axial througholes 42a, 42b, 42c
defining a plurality of corresponding passages through the piston
38. The rotatable member 44 is variably and rotatably movable
between a first rotatable position and a second rotatable position
for variably opening or closing the at least one axial throughole
(i.e., the axial througholes 42a, 42b and 42c in the illustrated
embodiment). As will be described in more detail below, the first
position for the rotatable member 44 allows relatively more fluid
flow through the at least one axial throughole than the second
position. In an exemplary embodiment, a degree of rotation of the
rotatable member 44 by the actuator 36 corresponds to a degree of
opening of the at least one axial throughole (and therefore also a
degree of opening of the at least one passage) by the rotatable
member 44.
[0022] In particular, the piston 38 of the illustrated embodiment
includes a radial wall portion 38a through which the at least one
passage is defined (i.e., the axial througholes 42a, 42b, and 42c
are defined in the radial wall portion 38a) and a cylindrical
sleeve wall portion 38b depending from the radial wall portion 38a.
By this arrangement, the rotatable member 44 can be cooperatively
received radially and axially within the cylindrical sleeve wall
portion 38b. The rotatable member also includes at least one
corresponding axial throughole, which is a plurality of
corresponding througholes 46a, 46b and 46c in the illustrated
embodiment. In particular, the corresponding plurality of axial
througholes 46a, 46b, 46c correspond with the axial througholes
42a, 42b and 42c of the piston 38. The rotatable member 44 is
rotatable by the actuator 36 from the first rotatable position
wherein the plurality of axial througholes 42a, 42b, and 42c and
the corresponding plurality of axial througholes 46a, 46b, 46c are
misaligned (e.g., fully misaligned) to inhibit flow through the at
least one passage and a second rotatable position wherein the
plurality of axial througholes 42a, 42b, 42c and the corresponding
plurality of axial througholes 46a, 46b, 46c are aligned (e.g., in
registry with one another). As shown, the rotatable member 44 of
the illustrated embodiment has a cup-like configuration similar to
the piston 38 (and can alternately be referred to as an inner
piston 44). In particular, in the illustrated embodiment, the
rotatable member 44 includes a radial wall potion 44a through which
the corresponding plurality of apertures 46a, 46b and 46c are
defined and a cylindrical sleeve wall portion 44b depending from
the radial wall portion 44a.
[0023] The rotatable member 44 is connected to the actuator 36 by
the spring 40 such that rotation of the spring 40 by the actuator
36 causes rotation of the rotatable member 44 relative to the
piston 38. More particularly, in the illustrated embodiment where
the actuator 36 is a motor, an output shaft 36a of the actuator 36
can be connected to the rotatable member 44 by the spring 40 for
transferring rotation movement of the output shaft 36a to the
rotatable member 44. In the illustrated embodiment, and with
particular reference to FIG. 3, a relief cap 50 is non-rotatably
fixed to the actuator 36 by a suitable fastener, such as the
illustrated screw 52. As shown, the relief cap 50 includes a head
portion 50a and a threaded shaft portion 50b extending therefrom.
The threaded shaft portion 50b is appropriately sized for a
threaded engagement with a threaded portion 32a of the relief bore
32 defined in the internal combustion engine 12. This threaded
engagement secures the active relief valve 20 within the relief
bore 32 of the internal combustion engine 12. Received within the
threaded shaft portion 50b of the relief cap 50 is a thrust bearing
54 that allows relative rotation as will be described below.
[0024] The spring 40 includes a first end 40a received within and
non-rotatably fixed to the rotatable member 44. In particular, the
first end 40a of the spring 40 is received within a groove inside
the cylindrical sleeve wall portion 44b of the rotatable member 44.
A second end 40b of the spring 40 is non-rotatably fixed to a
spring base 56. In particular, the second end 40b is received
within a circumferential groove 56a defined on a shaft portion 56b
of the spring base 56. The shaft portion 56b extends from a head
portion 56c that rests against the thrust bearing 54 and is able to
rotatably move relative to the relief cap 50 easily due to the
thrust bearing 54. As shown, the relief cap 50, the thrust bearing
54 and the spring base 56 can all be annularly disposed about the
output shaft 36a of the actuator 36. A locknut 58 can be threadedly
received on the output shaft 36a for axially securing the relief
cap 50, the thrust bearing 54 and the spring base 56 to the
actuator 36. The non-rotatable fixing of the first and second ends
40a, 40b of the spring 40, respectively to the rotatable member 40
and the spring base 56 can be through any known connection type,
including but not limited to welding, staking, interference fit
connection, etc.
[0025] To allow the actuator 36 to rotate the spring 40 and thereby
the rotatable member 44 relative to the piston 38, one of the
piston 38 and a wall 60 of the internal combustion engine 12
defining the relief bore 32 in which the active relief valve 20 is
disposed includes a protrusion 62 and the other of the piston 38
and the wall 60 includes an aperture 64 in which the protrusion 62
is received to prevent relative rotation between the wall 60 and
the piston 38. In the illustrated embodiment, the protrusion 62
extends radially outward from the cylindrical sleeve wall portion
38b of the piston 38 and the aperture 64 is defined in the wall 60
of the internal combustion engine 12 (see FIGS. 4-6). It is to be
appreciated by those skilled in the art that the protrusion could
be provided on the wall 60 and the aperture 64 defined in the
piston 38.
[0026] Returning reference to FIG. 1, the active pressure relief
valve system 10 can include the controller 22 operatively connected
to the actuator 36. In particular, the controller 22 can command
the active relief valve 20 to variably adjust the pressure of the
fluid 16 within the internal combustion engine 12. In addition, the
active pressure relief valve system 10 can include a pressure
sensor 70 operatively connected to the controller 22 that senses
the pressure of the fluid 16 within the internal combustion engine
12 and sends a signal to the controller 22 that is indicative of
the pressure sensed. The controller 22 can be configured to
variably adjust the pressure of the fluid 16 based on the signal
from the pressure sensor 70. In the illustrated embodiment, the
pressure sensor 70 is associated with a pressure sensor passage 72
that is fluidly connected to the main passage 34.
[0027] The active pressure relief valve system 10 of the
illustrated embodiment further includes a first discharge passage
74 fluidly connected to the relief bore 32 for discharging the
fluid 16 passing through the relief valve 20 to variably adjust the
pressure of the fluid 16 of the internal combustion engine 12 and a
second discharge passage 76 fluidly connected to the relief bore 32
for discharging the fluid 16 passing through the relief valve 20 to
limit the pressure of the fluid 16 in the internal combustion
engine to the maximum pressure threshold.
[0028] Though not shown, the actuator 36 can include a torsion
spring that urges the output shaft 36a in a first rotatable
direction when the actuator 36 is not commanded by the controller
22. Such rotation is, in turn, transmitted through the spring 40 to
thereby urge the rotatable member 44 toward the second rotatable
position so that when the controller 22 is not commanding the
pressure relief valve 20, the rotatable member 44 moves toward the
second rotatable position. In the second rotatable position, the
rotatable member can fully close the axial througholes 42a, 42b,
42c as best shown in FIG. 7. When the rotatable member 44 is in the
second rotatable position illustrated in FIG. 7 and the pressure of
the fluid 16 in the main passage 34 is below the maximum pressure
threshold, the active relief valve 20 will be as shown in FIG. 4
and no fluid flow of the fluid 16 will occur through the valve 20
to the first and second discharge passages 74, 76.
[0029] Optionally, an indicator 78 can be operatively connected to
the controller 22. The indicator 78 can be activated when there is
a failure of the active relief valve 20. For example, when the
actuator 36 fails to operate as expected when commanded by the
controller 22, the controller 22 can activate the indictor 78. The
indicator 78 could be, for example, a visual indictor that is
illuminated on the dashboard of the vehicle in which the engine 12
is disposed.
[0030] In operation, when the controller 22 commands the actuator
36 to rotate, the rotatable member 44 is rotated via the output
shaft 36a and the spring 40 relative to the piston 38. Such
rotation causes the corresponding plurality of througholes 46a,
46b, 46c to begin aligning with the axial througholes 42a, 42b, 42c
as shown in FIG. 8 and thereby allow the fluid 16 to pass through
the piston 44, and more generally through the active relief valve
20 and onto the first discharge passage 74 as shown in FIG. 5. The
degree of rotation of the rotatable member 44 corresponds to a
degree of alignment between the corresponding plurality of
apertures 46a, 46b, 46c and the axial througholes 42a, 42b, 42c of
the piston 38. The first rotatable position for the rotatable
member 44 can correspond to the corresponding plurality of
apertures 46a, 46b, 46c being in registry with the axial
througholes 42a, 42b, 42c, and thus a maximum opening amount is
provided through the piston 38 when the rotatable member 44 is
rotated to the first rotatable position as illustrated in FIG. 9.
As already mentioned, the degree to which the rotatable member 44
is rotated and thus the degree to which the axial througholes 42a,
42b, 42c in the piston 38 are opened can be controlled by the
controller 22 based on the sensed pressure within the main passage
34.
[0031] In the illustrated embodiment, the first position for the
rotatable member 44 is a position wherein the corresponding axial
througholes 46a, 46b, 46c are fully in registry with the axial
througholes 42a, 42b, 42c and the second position is a position
wherein the corresponding axial througholes 46a, 46b, 46c are fully
misaligned with the axial througholes 42a, 42b, 42c. This is not
required. The first position need only be a position wherein the
corresponding axial througholes 46a, 46b, 46c are at least
partially in registry with the axial througholes 42a, 42b, 42c and
the second position need only be a position wherein the axial
througholes are less open than the first position.
[0032] Under normal operating conditions, the system 10 can operate
in a computer controlled feedback loop wherein the controller 22
will command a specific required oil pressure based on engine and
vehicle operating conditions and the active relief valve 20 will
vary the relief flow area to achieve the pressure demanded by the
controller 22. If a failure occurs, the system can behave as a
standard two-stage mechanical oil pressure relief system. More
particularly, in the event of a failure, such as a power failure
within the associated vehicle whereby command of the actuator 36 by
the controller 22 ceases, the torsion spring within the actuator 36
operates to return the output shaft 36a and the rotatable member 44
to the second position wherein the rotatable member 44 inhibits
flow through the axial througholes 42a, 42b, 42c (FIG. 7). Should
pressure of the fluid 16 within the main passage 34 exceed the
maximum pressure threshold, the fluid 16 will axially move the
piston 38 as shown in FIG. 6 against the urging of the spring 40
and allow fluid flow from the main passage 34 through the second
discharge passage 76. Accordingly, the active relief valve 20
mechanically limits the pressure of the fluid 16 within the
internal combustion engine 12 to the maximum pressure threshold
because excess pressure within the main passage 34 causes the
active relief valve 20 to open fluid flow from the main passage 34
through the second discharge passage 76. In addition, the rotatable
member can be rotatably moved by the actuator 36 based on commands
from the controller 22 so that, under normal operating conditions,
the pressure of the fluid 16 within the internal combustion engine
12 can be variably and electronically adjusted.
[0033] Advantageously, the active relief valve 20 being configured
to variably and electrically adjust the pressure of the fluid 16
within the internal combustion engine 12 and further configured to
mechanically limit the pressure of the fluid 16 within the internal
combustion engine 12 to the maximum pressure threshold occurs
within a single active relief valve 20 that is disposed within only
a single relief bore 32 defined within the internal combustion
engine 12. Functionally, the system 10 behaves as an independently
controlled dual-stage relief system with one mechanical non-active
relief and one electro-mechanical active relief operating in
conjunction to control the engine oil pressure to a target value.
Structurally, the active relief valve 20 is located in the same
space envelope as a conventional standard mechanical system.
Advantageously, this reduces the number of modifications that would
be needed to adapt the system to a current conventional engine or
oil pump structure. In addition, the active pressure relief valve
system allows for complete active control of the engine operating
oil pressure while ensuring the durability and reliability of the
engine 12 during any failure condition. The control of the oil
pressure will allow the engine 12 to operate more efficiently but
will also continue to protect the engine from excessive
pressures.
[0034] An active pressure relief valve method for lubricating an
internal combustion engine will now be described. In particular,
the method will be described in association with the active
pressure relief valve system 10 described hereinabove, though this
is not required. In the method, the active relief valve 10 that is
disposed downstream from the pump 18 and fluidly connected to the
fluid reservoir 14 is provided for both variably adjusting pressure
of the fluid 16 pumped by the pump 18 within the internal
combustion engine 12 and limiting the pressure of the fluid 16
within the internal combustion engine 12 to the maximum pressure
threshold. The pressure of the fluid 16 within the internal
combustion engine 12 is variably and electronically adjusted via
the controller 22 operatively connected to the active relief valve
20. The pressure of the fluid 16 within the internal combustion
engine 12 is also passively and mechanically limited to a maximum
pressure threshold. As already described herein, adjusting the
pressure of the fluid 16 variably and electronically can include
controlling the actuator 36 to rotatably move the active relief
valve 20, and limiting the pressure of the fluid 16 can passively
and mechanically can include urging the piston 38 via the spring 40
toward the closed position (shown in FIG. 5) for inhibiting passage
of the fluid 16 until the pressure reaches the maximum pressure
threshold.
[0035] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives or varieties
thereof, may be desirably combined into many other different
systems or applications. Also that various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
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