WO2009023414A1

WO2009023414A1 - Torque feedback sensor

Info

Publication number: WO2009023414A1
Application number: PCT/US2008/071026
Authority: WO
Inventors: Larry A. Pritchard
Original assignee: Borgwarner Inc.
Priority date: 2007-08-13
Filing date: 2008-07-24
Publication date: 2009-02-19

Abstract

A coupling device (10) for use in a motor vehicle (30) has an input member (12) and at least one output member (14). At least one modulating clutch assembly (50) selectively couples the input member (12) to the output member (14). The modulating clutch assembly (50) includes an electrical clutch operator (54) and a plurality of clutch plates (80). The plurality of clutch plates (80) has a first plurality (82) of clutch plates (80) coupled to the input member (12) and a second plurality (84) of clutch plates (80) coupled to the output member (14), wherein the second plurality (84) of clutch plates (80) is interleaved with the first plurality (82) of clutch plates (80). A closed hydraulic cavity (92, 192) is disposed at a reaction side of the modulating clutch assembly (50). A pressure sensor (94, 194) is configured to measure pressure in the closed hydraulic cavity (92, 192).

Description

TORQUE FEEDBACK SENSOR

BACKGROUND

1. Field of the Invention

[0001] The present invention generally relates to clutch assemblies. More specifically, the invention relates to electrically actuated clutch assemblies.

2. Description of Related Art

[0002] Clutches which are activated or energized by electromagnetic coils are common components in rotary power transmission systems, both in stationary applications and in motor vehicles. Such electromagnetic clutches may be broadly characterized by whether they provide on-off energy transfer or modulating energy transfer. In the case of the former, dog clutches which may include auxiliary synchronizing devices are utilized whereas in the latter, friction clutch packs having a plurality of interleaved friction plates or discs are utilized. In either case, an electromagnetic operator which translates or compresses components of the clutch upon energization activates the clutch and upon deenergization, deactivates or relaxes the clutch.

[0003] Torque transfer devices, of the electrically actuated clutch type, proportionally transfer torque from an input shaft to an output shaft based on the amount of current applied to an electrical actuator. Each design requires the application of a certain amount of current to the electrical actuator to cause the clutch to transfer a given value of torque. A powertrain control unit (PCU) may be configured to apply current to engage the electrical actuator when desired.

[0004] There is a constant drive toward reducing electric current consumption of motor vehicle components, in order to increase gas mileage, among other advantages of such a reduction. Inter-active torque management systems have provided closed loop torque feedback systems that measure the amount of torque being applied, in order to determine the minimum amount of torque required. Applying the minimum amount of torque required helps reduce electric current consumption and also may reduce wear on components. Likewise, there is also a need to provide accurate levels of torque transfer in order to affect vehicle dynamics in prescribed fashion that promotes increased vehicle stability. In order to provide this functionality one must know the amount of torque transferred to the wheels during this maneuver, hence the need for torque feedback. Torque management systems may require additional components in a torque transfer device. However, reduction in the size, complexity, and cost of vehicle systems is also desired. [0005] In view of the above, it is apparent that there exists a need for a closed loop torque feedback system that has few components and low cost.

SUMMARY

[0006] In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides a novel torque feedback sensor that may be used in a closed hydraulic cavity located at a reaction side of a clutch assembly. A coupling device for use in a motor vehicle is provided. The coupling device has an input member and at least one output member. At least one modulating clutch assembly selectively couples the input member to the output member or members. The modulating clutch assembly includes an electrical clutch operator and a plurality of clutch plates. The plurality of clutch plates has a first group of clutch plates coupled to the input member and a second group of clutch plates coupled to the output member and/or members. The second group of clutch plates is interleaved with the first group of clutch plates. A closed hydraulic cavity is disposed at a reaction side of the modulating clutch assembly. A pressure sensor is configured to measure pressure in the closed hydraulic cavity. [0007] Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a schematic of a motor vehicle incorporating a coupling device according to the present invention;

[0009] Fig. 2 is a full, sectional view of a coupling device having a hydraulic cavity, according to the principles of the present invention;

[0010] Fig. 3 is a fragmentary, enlarged view of the coupling device having a hydraulic cavity of Fig. 2, incorporating the principles of the present invention; and

[0011] Fig. 4 is a fragmentary, enlarged view of a coupling device having another hydraulic cavity incorporating the principles of the present invention.

DETAILED DESCRIPTION

[0012] Referring now to the schematic of Fig. 1 , a coupling device 10 according to the present invention is shown incorporated into a motor vehicle 30. The motor vehicle 30 includes a motive source 32 such as an internal combustion engine or electric motor. A plurality of wheels 34 are coupled to the motive source 32 through a drive member 36 shown as a propeller shaft and output members 38 shown as an axle half-shaft. Two output members 38 are shown coupled to the drive member 36 using any embodiment of the coupling device 10. In this example, a differential 40 couples output shaft 14 with the two output members 38, shown as axle half-shafts.

[0013] A digital powertrain control unit (PCU) 42 is connected with the electrical clutch operator 54 of the coupling device 10 through, for example, a cable 44. The PCU 42 is configured to provide a range of electrical currents to a electrical clutch operator of coupling device 10 based on a desired amount of torque to be transferred from the drive member 36 to the output members 38. The desired amount of torque may be determined by the PCU 42 by reading a plurality of wheel speed sensors 46 and drive member sensor 47 providing information regarding the operational state of the motor vehicle 30. In addition, the amount of torque or torque setting of coupling device 10 may be measured (indirectly) with reference to a pressure signal received from a pressure sensor 94, which will be described in more detail below. Pressure sensor 94 communicates with data receiver 49. [0014] Referring now to Fig. 2, a section view of the coupling device 10 of the present invention is illustrated in more detail. As its primary components, the coupling device 10 includes an input member 12 selectively coupled to an output member 14 by a modulating clutch assembly 50 having a ball ramp operator 52. The input member 12 may be disposed in a substantially coaxial relationship with the output member 14, as shown in Fig. 2, or the input and output members 12 and 14, may have be disposed in another relationship, such as a substantially perpendicular relationship. One example of a coupling device having one or more modulating clutch assemblies and including a ball ramp operator is disclosed in U.S. Patent No. 6,905,008 to Kowalsky which is herein incorporated by reference. Another example is disclosed in U.S. Patent No. 5,839,328 to Showalter which is herein incorporated by reference.

[0015] The modulating clutch assembly 50 selectively transfers torque from the input member 12 to the output member 14 by activating an electrical clutch operator 54 of the modulating clutch assembly 50. The electrical clutch operator 54 may be operable to engage a pilot clutch pack 56, as described below, or the pilot clutch pack 56 may be omitted, and the electrical clutch operator 50 may activate and control a main clutch pack 58 in any other suitable way. [0016] The electrical clutch operator 54 may comprise a solenoid coil 60, which may be energized to urge an annular solenoid plunger 62 toward the left, as illustrated in Fig. 2. As the solenoid plunger 62 moves to the left, the air gap between the frusto-conical surfaces 64, 66 closes and the solenoid plunger 62 pulls studs 68 to the left. The studs 68 are attached to a pressure plate 70, such that that when the studs 68 move to the left by virtue of the solenoid plunger 62 moving to the left, the pressure plate 70 also moves to the left to compress the pilot clutch pack 56. The pilot clutch pack 56 has a first plurality of clutch plates 71 coupled with the input member 12, and a second plurality of clutch plates 73 coupled with a clutch hub 72.

[0017] Upon being compressed, the pilot clutch pack 56 engages the ball ramp operator 52 to transfer torque between the input and output members 12, 14 through pilot and main clutches 56, 58. More particularly, the circular clutch hub 72 is freely rotatably disposed upon the output member 14. A plurality of ramped recesses 74 is disposed in a circular pattern about the axis of the output member 14. Disposed within the recesses 74 are load transferring members, such as ball bearings 76 or similar components, which roll along the ramps defined by the recesses 74. A circular member 78 is disposed in opposed relation with the circular clutch hub 72 and includes a like plurality of complimentary sized recesses 74. Upon compression of the pilot clutch pack 56, the circular clutch hub 72 is pulled away from the circular member 78, causing the ball bearings 76 to ride up the recesses 74. As the ball bearings 76 ride up the recesses 74, the circular clutch hub 72 and the circular member 78 are driven apart. When the circular member 78 is driven away from the circular clutch hub 72, the circular member 78 acts as an apply plate to compress the main clutch pack 58.

[0018] Upon compression, the main clutch pack 58 transfers torque to the output member 14. More specifically, the main clutch pack 58 comprises a plurality of interleaved clutch plates 80. A first group 82 of the clutch plates 80 is coupled to the input member 12, either by being directly coupled or selectively coupled, for example by virtue of the pilot clutch pack 56 described above. A second group 84 of clutch plates 80 is coupled with the output member 14. When compressed, the first and second pluralities 82, 84 of clutch plates 80 rotate together, and main clutch pack 58 thereby couples the input member 12 to the output member 14. The magnitude of current applied to solenoid coil 60 is related to the compressive force applied to frictionally couple clutch plates 80. Accordingly, the torque transfer through coupling device 10 from input member 12 to output member 14 is modulated by the applied current.

[0019] Referring now to Figs. 2 and 3, a high pressure, annular piston 88 is connected to the reaction side, or distal end 86, of the main clutch pack 58. The piston 88 may be connected to the last clutch plate 80 of the main clutch pack 58, or the piston 88 may be coupled to the main clutch pack 80 in any other suitable manner, such as by being connected to an apply plate 89. The piston 88 is received by a piston chamber 90 formed in or inserted in the back plate 91 , wherein the piston chamber 90 defines a closed hydraulic cavity 92. Preferably, the hydraulic cavity 92 is a sealed chamber containing a liquid. The liquid is preferably a generally incompressible fluid, such as oil. It is also contemplated, within the spirit and scope of the present invention, that the hydraulic cavity 92 could have hydraulic fluid lines extending therefrom to fluidly connect a pressure sensor 94 or other components, so long as the cavity 92 and accompanying lines remain closed during operation. In other words, significant volumes of fluid within the cavity 92 or accompanying lines is not extracted and additional fluid is not added during operation. [0020] A pressure sensor 94, probe, or transducer is located within the hydraulic cavity 92 or in fluid communication with the hydraulic cavity. The pressure sensor 94 is configured to sense pressure, or a change in pressure, within the hydraulic cavity 92. The pressure sensor 94 is preferably a telemetric pressure sensor having a transmitter and an internal battery, and as such the pressure sensor 94 may rotates with the hydraulic cavity 92 and back plate 91. The signal of the pressure sensor 94 may be transmitted by radio frequency or another signal and picked by a corresponding antenna associated with receiver 49. Any suitable pressure sensor or transducer could be used in the pressure sensor 94, as one having ordinary skill in the art would understand. For example, the pressure sensor 94 could be a piezoelectric device which transmits a signal to an antenna, which further sends the signal to the receiver 49 and the PCU 42 regarding the real time hydraulic fluid pressure within the hydraulic cavity 92.

[0021] As the main clutch pack 58 is compressed by the apply plate 78, the piston 88 compresses the fluid within the hydraulic cavity 92. As the piston 88 compresses the fluid within the hydraulic cavity 92, the pressure sensor 94 measures the increasing pressure within the hydraulic cavity 92. The pressure measurement may be correlated to the apply load on the main clutch pack 58 and the corresponding torque being transmitted by the coupling device 10. The pressure in the hydraulic cavity 92 may be directly proportional or correlated to the force being applied to the main clutch pack 58. The pressure signal from the pressure sensor 94 may be provided to a controller, such as the PCU 42, and closed loop control of torque capacity may be effectuated, if desired.

[0022] Referring now to Fig. 4, another embodiment of a hydraulic cavity 192 for use with a main clutch pack 58 is illustrated. Like the hydraulic cavity 92 of Figs. 2-3, the hydraulic cavity 192 of Fig. 4 is formed within or otherwise inserted into the back plate 91 of the main clutch pack 58. The hydraulic cavity 192 is a sealed chamber comprising a fluid. The fluid is preferably a generally incompressible fluid, such as water or oil. [0023] The hydraulic cavity 192 has a relatively thin, deflectable plate 188 comprising one of its sides, wherein the thin deflectable plate 188 has an inner side 196 in contact with hydraulic fluid located within the hydraulic cavity 192. The deflectable plate 188 has an outer side 198 that is in contact with the main clutch assembly 58, either by being in direct contact with the last clutch plate 80, or by being in contact with another member (not shown) that is connected to the last clutch plate 80.

[0024] A pressure sensor 194, or a pressure sensor probe, is located within the hydraulic cavity 192. In the alternative, the pressure sensor 194 could be in fluid communication with the hydraulic cavity 192 in another manner. The pressure sensor 194 is preferably a telemetric pressure sensor, as described above. As a load is applied to the main clutch assembly 58, the clutch plates 80 will transmit the load to the deflectable plate 188. As a result, the deflectable plate 188 will be slightly deflected into the hydraulic cavity 192, which will cause the pressure within the hydraulic cavity 192 to increase. The pressure sensor 194 obtains a pressure measurement, which may be correlated to the apply load on the main clutch pack 58 and the torque being transmitted by the coupling device 10. The pressure in the hydraulic cavity 192 may be directly proportional or correlated to the force being applied to the main clutch pack 58. The pressure signal from the pressure sensor 194 may be provided to a controller, such as the PCU 42 via receiver 49, and closed loop control of torque capacity may be effectuated, if desired.

[0025] Other instances of the electrical clutch operator 54 may have other appropriate configurations instead of including a solenoid coil 60 and a pilot clutch pack 56. Other examples include, but are not limited to, electromechanical devices and electrohydraulic devices. The coupling device 10 may include any appropriate electric motor configured to mechanically compress the interleaved clutch plates 80, without falling beyond the spirit and scope of the present invention. An electrohydraulic device may include an electric pump and/or an electrically actuated valve to hydraulically compress the interleaved clutch plates 80. [0026] As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims.

Claims

CLAIMSI claim:

1. A coupling device (10) for use in a motor vehicle (30) powertrain for selectively coupling torque from a rotating input member (12) to one or more output members (14), the coupling device (10) comprising: a modulating clutch assembly (50) selectively coupling the input member (12) to the output member (14), the modulating clutch assembly (50) including a plurality of clutch plates (80) having one or more first clutch plates (82) coupled to the input member (12), and one or more second clutch plates (84) coupled to the output member (14) and interleaved with the first clutch plates (82), the modulating clutch assembly including a clutch operator applying a variable compressive force acting on the clutch plates to modulate the frictional coupling and the torque transfer between the first and second clutch plates; a hydraulic cavity (92, 192) disposed at a reaction side of the modulating clutch assembly (50) responsive to the compressive force acting on the clutch plates applied by the clutch operator; and a pressure sensor (94, 194) configured to measure pressure in the closed hydraulic cavity (92, 192) which is related to the frictional and torque coupling between the first and second clutch plates.

2. The coupling device (10) of claim 1 , wherein the hydraulic cavity (92, 192) is sealed.

3. The coupling device (10) of claim 1 , wherein the hydraulic cavity (92, 192) is filled with a liquid.

4. The coupling device (10) of claim 1 , further comprising a piston (88) disposed at the reaction side of the modulating clutch assembly (50), the hydraulic cavity (92) formed by a piston chamber (90) receiving the piston (88).

5. The coupling device (10) of claim 4, the piston (88) being configured to pressurize fluid within the hydraulic cavity (92) when the compressive force is applied to the modulating clutch assembly (50).

6. The coupling device (10) of claim 4, wherein the piston (88) is coupled to a clutch plate (80) at the reaction side of a main clutch pack (58) of the modulating clutch assembly (50).

7. The coupling device (10) of claim 1 , wherein the hydraulic cavity (192) is filled with a fluid, and the hydraulic cavity (192) has a side comprising a deflectable plate (188), the deflectable plate (188) having an inner side (196) contacting the fluid.

8. The coupling device (10) of claim 7, wherein the deflectable plate (188) has an outer side (198) that is selectively compressed by a member (80) located at the reaction side of the modulating clutch assembly (50).

9. The coupling device (10) of claim 8, wherein the member is a clutch plate (80).

10. The coupling device (10) of claim 1 , wherein the pressure sensor (94, 194) is a telemetric pressure sensor.

11. The coupling device (10) of claim 10 further comprising a data receiver for receiving data from the telemetric pressure sensor and providing signals to a powertrain control unit, the powertrain control unit providing control signals to the modulating clutch assembly.

12. The coupling device (10) of claim 1 , wherein the clutch operator includes an electrical clutch operator.

13. The coupling device (10) of claim 12, wherein the electrical clutch operator (54) comprises a solenoid coil (60).

14. The coupling device (10) of claim 13, further comprising: a pilot clutch pack (56) having a first plurality of pilot clutch plates (71 ) coupled to the input member (12) and a second plurality of pilot clutch plates (73) coupled to a clutch hub (72), the second plurality of pilot clutch plates (73) being interleaved with the first plurality of pilot clutch plates (71 ); and a pressure plate (70) adjacent to the pilot clutch pack (56), wherein energization of the solenoid (60) coil translates a solenoid plunger (62), causing the pressure plate (70) to compress the pilot clutch pack (56).

15. The coupling device (10) of claim 14, wherein compression of the pilot clutch pack (56) engages a ball ramp operator (52) to compress the clutch plates (80) of a main clutch pack (58) of the modulating clutch assembly (50).