U.S. patent application number 09/822612 was filed with the patent office on 2001-11-01 for active control of a hydra-mechanical traction control device.
Invention is credited to Porter, Fred C..
Application Number | 20010035323 09/822612 |
Document ID | / |
Family ID | 26891483 |
Filed Date | 2001-11-01 |
United States Patent
Application |
20010035323 |
Kind Code |
A1 |
Porter, Fred C. |
November 1, 2001 |
Active control of a hydra-mechanical traction control device
Abstract
The hydraulic coupling according to the present invention
generally includes a multi-plate clutch assembly operatively
connecting a pair of rotary members, an actuator assembly for
actuating the clutch assembly, and a fluid control system operable
for controlling actuation of the actuator assembly. The actuator
assembly includes a hydraulic pump and a piston mounted in a piston
chamber for movement relative to the multi-plate clutch assembly.
The fluid control system regulates the fluid pressure supplied to
the piston chamber by the hydraulic pump to control the clutch
engagement force exerted by the piston on the clutch assembly. The
fluid control system includes an electrically-controlled flow
control valve operable for regulating the fluid pressure delivered
to the piston chamber. Preferably, the flow control valve is a
pulse-width modulated (PWM) valve having a moveable valve element.
The position of the valve element is controlled by an electronic
traction control module that monitors and responds to certain
vehicle operating conditions, including a sump fluid temperature, a
coupling outlet oil temperature, the four wheel speeds, and the
piston chamber pressure. The electronic traction control module
sends a control signal to the PWM control valve for modulating the
hydraulic pressure supplied to the piston chamber, which, in turn,
controls clutch engagement.
Inventors: |
Porter, Fred C.; (Beverly
Hills, MI) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, PLC
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
26891483 |
Appl. No.: |
09/822612 |
Filed: |
March 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60195930 |
Apr 10, 2000 |
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Current U.S.
Class: |
192/35 ;
192/103F; 192/82T |
Current CPC
Class: |
F16D 48/04 20130101;
F16D 2500/1026 20130101; B60W 2510/0291 20130101; F16D 2500/3024
20130101; F16D 25/14 20130101; F16D 2048/0242 20130101; F16D 48/02
20130101; B60W 2510/0241 20130101; F16D 2500/7109 20130101; F16D
2500/7041 20130101; F16D 2500/3056 20130101; F16D 2500/7044
20130101; F16D 2500/70404 20130101; F16D 2500/3115 20130101; F16D
48/064 20130101 |
Class at
Publication: |
192/35 ;
192/82.00T; 192/85.0AA; 192/103.00F |
International
Class: |
F16D 025/02; F16D
025/0638; F16D 043/284 |
Claims
What is claimed is:
1. A hydraulic coupling for use in a driveline apparatus for a
motor vehicle to rotatively couple first and second rotary members,
the hydraulic coupling comprising: a transfer clutch operatively
connected between the first and second rotary members; a piston
housing defining a piston chamber; a piston disposed in said piston
chamber and actuable to engage said transfer clutch and rotatively
couple the first and second rotary members; a hydraulic pump in
fluid communication with a sump containing hydraulic fluid and
providing a pumping action in response to relative rotation between
the first and second rotary members; a first fluid flow path for
supplying hydraulic fluid from said hydraulic pump to said piston
chamber; a control valve located in fluid communication with said
first flow path for regulating flow of hydraulic fluid into said
piston chamber for actuating said piston; a second flow path for
supplying hydraulic fluid from said control valve to a clutch
chamber to cool said transfer clutch; a first temperature sensor
for detecting the temperature of hydraulic fluid in said sump; a
second temperature sensor for detecting the temperature of
hydraulic fluid in said clutch chamber; a pressure sensor for
detecting the pressure of fluid in said piston chamber; and an
electronic traction control module controlling actuation of said
control valve in response to sensor signals from said sensors.
2. The hydraulic coupling of claim 1 wherein said transfer clutch
includes a hub fixed for rotation with the first rotary member, a
drum fixed for rotation with the second rotary member, and a
multi-plate clutch pack interconnected between said hub and said
drum.
3. The hydraulic coupling of claim 2 wherein said piston housing is
connected between said drum and a pump cover assembly that is fixed
to the second rotary member, said hydraulic pump being retained in
said pump cover assembly and having a first pump member fixed for
rotation with said cover assembly and a second pump member fixed
for rotation with the second rotary member such that relative
rotation between said first and second pump members generates said
pumping action.
4. The hydraulic coupling of claim 1 wherein said first temperature
sensor generates a first temperature signal that is delivered to
said control module, said control module having logic for modifying
controlled actuation of said control valve in response to
variations in said first temperature signal which are sensor
indicative of fluid viscosity changes.
5. The hydraulic coupling of claim 4 wherein said second
temperature sensor generates a second temperature signal that is
delivered to said control module, said control module having logic
for releasing said transfer clutch when said second temperature
signal exceeds a predetermined maximum value.
6. The hydraulic coupling of claim 5 wherein said pressure sensor
sends a pressure signal to said control module for limiting the
maximum torque transferred by said transfer clutch when said
pressure exceeds a predetermined maximum value.
7. The hydraulic coupling of claim 1 wherein said second
temperature sensor generates a second temperature signal that is
delivered to said control module, said control module having logic
for releasing said transfer clutch when said second temperature
signal exceeds a predetermined maximum value.
8. The hydraulic coupling of claim 7 wherein said pressure sensor
sends a pressure signal to said control module for limiting the
maximum torque transferred by said transfer clutch when said
pressure exceeds a predetermined maximum value.
9. The hydraulic coupling of claim 1 wherein said pressure sensor
sends a pressure signal to said control module for limiting the
maximum torque transferred by said transfer clutch when said
pressure exceeds a predetermined maximum value.
10. The hydraulic coupling of claim 1 further comprising first and
second speed sensors to measure the rotary speed of the first and
second rotary members and send first and second speed signals to
said control module, said control module operable to control
actuation of said transfer clutch in response to a speed
differential between the rotary members.
11. The hydraulic coupling of claim 1 further comprising a housing
rotatably supporting the first and second rotary members, said
housing defining a valve body receiving said control valve and
having an inlet passage communicating with an outlet of said pump,
a first supply passage, and a first exhaust passage, said piston
housing defining a second supply passage in communication with said
piston chamber and said first supply passage, and a second exhaust
passage in communication with said first exhaust passage, said
control valve operable to deliver high pressure fluid through said
first and second supply passages to said piston chamber and to
deliver low pressure fluid through said first and second exhaust
passages to said clutch chamber.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to couplings for use
in motor vehicle driveline applications. More specifically, the
coupling includes a hydraulic pump, a transfer clutch coupled
between a pair of rotary members, and a fluid distribution system
for controlling actuation of the transfer clutch.
BACKGROUND OF THE INVENTION
[0002] Hydraulic couplings are used in a variety of motor vehicle
driveline applications for limiting slip and transferring drive
torque between a pair of rotary members. In all wheel drive
applications, hydraulic couplings have been used to automatically
control the transfer of drive torque from a driven member to a
non-driven member in response to speed differentiation
therebetween. In limited slip applications, such as used in
association with a differential in an axle assembly, full-time
transfer case, or transaxle, hydraulic couplings have been used to
limit slip and bias the torque split between two rotary members.
Examples of known hydraulic couplings which are adaptable for such
driveline applications include viscous couplings, geared traction
units, and passively and electronically-controlled
hydraulically-actuated friction clutches generally similar to those
shown and described in U.S. Pat. Nos. 5,148,900, 5,358,454,
4,649,459, 5,704,863, 5,779,013, and 6,051,903.
[0003] In response to increased consumer demand for motor vehicles
with traction control systems, hydraulic couplings are currently
being used in a variety of driveline applications. Such hydraulic
couplings rely on hydromechanics and pressure-sensitive valve
elements to passively respond to a limited range of vehicle
operating conditions. These hydraulic couplings are susceptible to
improvements that enhance their performance, such as a more
controlled response to a wider range of vehicle operating
conditions. With this in mind, a need exists to develop improved
hydraulic couplings that advance the art.
SUMMARY OF THE INVENTION
[0004] Accordingly, the present invention provides a hydraulic
coupling for use in motor vehicle driveline applications for
rotatively coupling a pair of rotary members to limit speed
differentiation and transfer drive torque therebetween.
[0005] The hydraulic coupling according to the present invention
generally includes a multi-plate clutch assembly operatively
connecting a pair of rotary members, an actuator assembly for
actuating the clutch assembly, and a fluid control system operable
for controlling actuation of the actuator assembly. The actuator
assembly includes a hydraulic pump and a piston mounted in a piston
chamber for movement relative to the multi-plate clutch assembly.
The fluid control system regulates the fluid pressure supplied to
the piston chamber by the hydraulic pump to control the clutch
engagement force exerted by the piston on the clutch assembly. The
fluid control system includes an electrically-controlled flow
control valve operable for regulating the fluid pressure delivered
to the piston chamber. Preferably, the flow control valve is a
pulse-width modulated (PWM) valve having a moveable valve element.
The position of the valve element is controlled by an electronic
traction control module that monitors and responds to certain
vehicle operating conditions including, without limitation, a sump
fluid temperature, a coupling outlet oil temperature, the four
wheel speeds, and the piston chamber pressure. The electronic
traction control module sends a control signal to the PWM control
valve for modulating the hydraulic pressure supplied to the piston
chamber, which, in turn, controls clutch engagement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Further objects, features and advantages of the present
invention will become readily apparent from the following detailed
specification and the appended claims which, in conjunction with
drawings, set forth the best mode now contemplated for carrying out
the invention. Referring to the drawings:
[0007] FIG. 1 is a sectional view illustrating a hydraulic coupling
according to the present invention operatively coupled between
first and second rotary members;
[0008] FIG. 2 is a schematic illustration of a hydraulic circuit
associated with the hydraulic coupling of FIG. 1; and
[0009] FIG. 3 is a diagramatical illustration of the hydraulic
circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] In general, the present invention is directed to an
actively-controlled hydromechanical limited slip and torque
transfer apparatus, hereinafter referred to as a hydraulic
coupling. The hydraulic coupling is well-suited for vehicular
driveline applications requiring torque transfer or slip limiting
control between a pair of rotary members. Driveline applications
for the hydraulic coupling include, but are not limited to, limited
slip axle differentials, power take-offs and in-line coupling for
all-wheel drive vehicles, on-demand couplings and limited slip
differentials in four-wheel drive transfer cases, and limited slip
differentials in transaxles.
[0011] Referring initially to FIG. 1 of the drawings, a hydraulic
coupling according to a preferred embodiment of the present
invention is generally identified with reference numeral 10. As
specifically shown in FIG. 1, hydraulic coupling 10 is located in a
driveline apparatus having a housing 12 and is operatively coupled
between a first rotary member, hereinafter referred to as first
shaft 14, and second rotary member, hereinafter referred to as
second shaft 16. Shafts 14 and 16 are rotatable relative to one
another, with first shaft 14 being supported by a bearing assembly
18 for rotation relative to second shaft 16. Bearings 20 and 22 and
24 are also provided for supporting shaft 14 and 16, respectively,
for rotation relative to housing 12. As will become apparent,
hydraulic coupling 10 is controlled by an electronic traction
control module 26 for automatically controlling torque transfer and
speed differentiation between shafts 14 and 16. Electronic traction
control module 26 monitors vehicle system information and hydraulic
coupling information including, but not limited to, wheel speed,
oil sump temperature, oil outlet temperature, clutch pressure, and
controls a pulse-width modulated (PWM) flow control valve assembly
28 associated with hydraulic coupling 10.
[0012] In general, hydraulic coupling 10 comprises two portions: an
actuator assembly 30, and a transfer clutch 32 for transferring
drive torque from a faster rotating shaft to a slower rotating
shaft in response to excessive speed differentiation therebetween.
Transfer clutch 32 is a hydraulically-actuated multi-plate clutch
assembly operably coupled between first shaft 14 and second shaft
16. Actuator assembly 30 includes a hydraulic pump 34 and a piston
assembly 36. Hydraulic pump 34 is confined within a cover assembly
38 which includes a cylindrical outer drum 40 and a cover plate 42
secured via fasteners 44 thereto. Cover assembly 38 is fixed for
rotation with second shaft 16 and, in the embodiment shown, outer
drum 40 is integral with second shaft 16. Preferably, hydraulic
pump 34 is a bi-directional gerotor pump having a first toothed
pump member 46 fixed (i.e., splined) for rotation with first shaft
14, an eccentric ring 48 fixed to outer drum 40, and a second
toothed pump member 50 therebetween. With such an arrangement,
relative rotation between first shaft 14 and second shaft 16
results in a pumping action which draws fluid from an inlet chamber
52 on the suction side of pump 34 to an outlet chamber 54 on the
discharge side of pump 34. To facilitate pumping action in both
directions of rotation, hydraulic pump 34 includes suitable one-way
check valves similar to the arrangement shown in commonly-owned
U.S. Pat. No. 6,041,903 which is incorporated by reference. Inlet
chamber 52 is in fluid communication with fluid-filled sump 56
(FIG. 2) provided within housing 12.
[0013] Transfer clutch 32 includes a clutch hub 58 fixed via a
splined connection 60 to first shaft 14, an outer drum 62 coupled
via a piston housing 64 to cover assembly 38, and a clutch pack 66
having a plurality of inner clutch plates fixed (i.e., splined) to
clutch hub 56 that are interleaved with a plurality of outer clutch
plates fixed (i.e., splined) to outer drum 62. Outer drum 62 is
journaled for rotation relative to first shaft 14. In addition,
outer drum 62 is rigidly connected (i.e., welded) to an end plate
segment 72 of piston housing 64 which, in turn, is fixed via
splined connection 74 to cover plate 42. A first exhaust passage 76
formed in housing 12 communicates with a second exhaust passage 78
in piston housing 64 for exhausting fluid from PWM flow control
valve assembly 28 into a clutch chamber 80 to provide an adequate
supply of lubricating fluid for cooling and lubricating clutch pack
66.
[0014] Piston assembly 36 includes a piston chamber 82 that is
formed in plate segment 72 of piston housing 64, and an actuation
member or piston 84 disposed in annular piston chamber 82. Piston
84 is supported for axial sliding movement within piston chamber 82
relative to interleaved multi-plate clutch pack 66 for selectively
applying a compressive clutch engagement force thereon, thereby
transferring drive torque from first shaft 14 (via clutch hub 58)
to second shaft 16 (via drum 62, piston housing 64, and cover
assembly 38) or vise versa.
[0015] A first fluid supply passage 86 is formed in housing 12
between PWM flow control valve assembly 28 and piston chamber 82.
First supply passage 86 communicates with a second supply passage
88 formed in piston housing 64. An inlet passage 90 is formed in
housing 12 for providing fluid communication between outlet chamber
54 of pump 34 and the inlet to PWM flow control valve assembly 28.
A pressure relief valve 92 is provided in inlet passage 90 for
preventing the pressure delivered to control valve assembly 28 from
exceeding a predetermined maximum level. The amount of drive torque
transferred is proportional to the magnitude of the clutch
engagement force exerted by piston 84 on clutch pack 66 which, in
turn, is a function of the fluid pressure within piston chamber 82.
The magnitude of the control fluid pressure (P.sub.C) delivered to
piston chamber 82 is determined by PWM flow control valve assembly
28 which has a moveable valve element, the position of which is
controlled by an electric control signal generated by control
module 26. The remaining fluid is exhaust through passages 76 and
78 at an exhaust pressure (P.sub.E) which is the difference between
the pump pressure P.sub.G generated by gerotor pump 34 and the
control pressure P.sub.C. As is known, the control pressure P.sub.C
can be closely controlled due to the use of PWM valve 28.
[0016] As seen, ring seals 98 are provided for sealing piston
housing 64 for rotation relative to housing 12. Ring seals 98 allow
fluid passages 76 and 86 to communicate between housing 12 and
piston housing 64. Moreover, ring seals 100 are provided between
cover plate 42 and housing 12 to provide a fluid tight seal
therebetween. An annular chamber 102 formed in housing 12 provides
fluid communication between outlet chamber 54 and inlet passage 90.
A thrust bearing 104 is shown between housing 12 and plate segment
72 of piston housing 64.
[0017] It was previously noted that electronic control module 26
monitors vehicle system information and certain hydraulic coupling
information including wheel speed, oil sump temperature, the oil
outlet temperature, and clutch pressure. In particular, the wheel
speeds are detected by four (4) wheel speed sensors 106A-106D which
are disposed on, or in close proximity to, each of the vehicles'
wheels. The oil sump temperature is measured by a first temperature
sensor 106 which is disposed in oil sump 56. The oil outlet
temperature is detected by a second temperature sensor 108 located
in proximity to the terminal end of second exhaust passage 78. The
clutch pressure is detected by a clutch pressure sensor 110 which
may be disposed in piston chamber 82 or in one of supply passages
86 and 88.
[0018] The electronic control module 26 employs a main algorithm
which determines the desired clutch pressure based upon the
difference in front wheel and rear wheel speed (.DELTA..sub.S). An
exemplary characteristic curve for P.sub.C versus .DELTA..sub.S is
shown in FIG. 2 to illustrate the manner in which the control
pressure P.sub.C can be controlled to change with .DELTA..sub.S.
The present invention functions to modulate the clutch apply
pressure through the use of PWM solenoid valve 28 with the main
algorithm control logic and closed loop control. Lacking any
difference in speed between shafts 14 and 16, pump 34 turns as a
unit and creates no hydraulic flow. Upon introduction of
differential speeds, the pump elements begin relative motion and
commence hydraulic flow. The pressure generated by pump 34 is fed
to inlet passage 90 for delivery to the inlet of PWM solenoid valve
28. Pulsations in pressure due to gerotor lobes may need to be
dampened with an accumulator 112 or other suitable means. The PWM
valve duty cycle is controlled electronically by electronic control
module 26 based upon the logic of the main algorithm and inputs
from wheel speed sensors 104 and 104D (ABS), pressure transducer
110 and temperature sensors 106 and 108. A second pressure
transducer 114 can be used to provide a pressure signal to
controller 26 from inlet passage 90. The wheel speed sensors are
used to control the duty cycle of the PWM valve 28 that, in turn,
controls the pressure being fed to piston chamber 82. They also
signal controller 26 that a non-standard tire size (mini-spare) is
on the vehicle so that the system can be deactivated or operating
characteristics can be changed.
[0019] Pressure transducer 110 signals controller 26 how much
torque is being transferred so that logic can control the torque
according to predetermined requirements. It also can be used to
limit the maximum torque transfer so that the system components can
be down sized for mass and cost savings. Sump temperature sensor
106 is used to compensate for fluid viscosity changes on the inlet
side of pump 34. An exemplary viscosity compensation chart is shown
in FIG. 2 (labled "viscosity compensation"). With the fluid
viscosity (V) decreasing as the sump fluid temperature (T.sub.S)
increase. The clutch outlet oil temperature sensor 108 is used to
deactivate transfer clutch 32 during thermally abusive operation,
thereby preventing clutch damage. An exemplary clutch deactivation
curve is shown in FIG. 2 (labeled "thermal overload").
[0020] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *