JP2005076699A - Electromagnetic clutch assembly improved in generation of torque - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clutch of low power consumption, particularly used in an automobile. <P>SOLUTION: This electromagnetic clutch assembly having a ball lamp actuator is improved in its torque generating performance. This electromagnetic clutch assembly 70 has a primary or pilot frictional clutch pack 130 and a secondary or main frictional clutch pack 170. The ball lamp actuator operated by the primary or pilot frictional clutch pack 130 has a plastic washer 160 or ring adjacent to one of actuator members. The plastic washer 160 improves the action of the main frictional clutch pack 170, and increases the compression force added to the secondary or main clutch pack, whereby the feedback action for improving the torque processing performance of the electromagnetic clutch assembly 70 is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  This application is filed under US Provisional Patent Application No. 60/90, filed May 29, 2002, which is hereby incorporated by reference and is incorporated herein by reference, under 35 USC 119 (e). The benefit of the filing date of 383,992 is claimed.

  The present invention relates generally to electromagnetic clutches, and more particularly to an electromagnetic clutch having a ball ramp actuator and improved torque throughput characteristics.

  A clutch actuated or excited by an electromagnetic coil is a special common component in a rotational power transmission system, both in stationary applications and in automobiles. Such electromagnetic clutches can be broadly characterized depending on whether they start or stop energy transmission or regulate energy transmission. In the former case, a meshing clutch that can include an auxiliary tuning device is utilized, while in the latter, a friction clutch pack having a plurality of alternating friction plates or disks is utilized. In either case, an electromagnetic clutch actuator that translates or compresses the components of the clutch activates the clutch when energized and deactivates or relaxes the clutch when energized.

  One design and operating characteristic of electromagnetic clutches that is a significant technical concern is power consumption. In particular, it is desirable to design and utilize low power consumption clutches in automobiles. Low power consumption is desirable in itself, but it reduces the heat generated by the coil, so low power consumption reduces the need for coil cooling and reduces the useful life of the coil. Stretching, thereby improving the overall desired design goals.

  Designs that exhibit low power consumption are generally referred to as cam or ball ramp actuated clutches. In this case, a pair of opposed plates having camming members or opposed arcuate recesses that receive ball or roller bearings rotate relatively due to resistance forces resulting from excitation of the electromagnetic coil. When separated. Such separation compresses adjacent friction clutch packs, thereby transmitting drive energy or torque through the friction clutch packs. Such a device is disclosed in connection with the transfer case of US Pat. No. 4,989,686, which is shared by the assignee of the present invention.

  In addition to reducing power consumption, another constant goal of clutch design is to increase torque generation. The present invention is directed to a cam operated clutch having an increased torque generation amount.

  An electromagnetic clutch assembly having a ball ramp actuator improves torque handling capability. The electromagnetic clutch assembly has a primary or pilot friction clutch pack and a secondary or main friction clutch pack. A ball ramp actuator actuated by a primary or pilot friction clutch pack includes a plastic washer or ring adjacent to one of the actuator members. The plastic washer improves the action of the primary friction clutch pack and enhances the compressive force applied to the secondary or main clutch pack, thus providing a feedback action that increases the torque handling capacity of the electromagnetic clutch assembly.

Thus, one object of the present invention is to provide a cam operated electromagnetic clutch with improved torque handling capability.
It is a further object of the present invention to provide a cam actuated electromagnetic clutch for use in truss case, rear axle and other driveline components of an automobile.

  Further objects and advantageous effects of the present invention will become apparent by referring to the following description of preferred embodiments and the accompanying drawings in which identical components, elements or working parts are indicated by like reference numerals. I will.

BEST MODE FOR CARRYING OUT THE INVENTION

  First, in FIG. 1, a drive train of a four-wheel drive vehicle embodying the present invention is shown schematically and denoted by reference numeral 10. The drive train 10 of the four-wheel drive vehicle has a prime mover 12 that is connected to the transaxle 14 and directly drives the transaxle 14. The output of the transaxle 14 drives a bevel gear set or a twisted bevel gear set 16, which is a front or primary propulsion shaft 22, a front or primary differential 24, and a pair of operable fronts. Power is provided to the primary or front drive line 20, which includes an axle 26 and a pair of front or primary tires and wheel assemblies 28, respectively. It should be understood that the previous or primary differential 24 is conventional.

  The bevel gear set or torsional gear set 16 also includes a secondary propulsion shaft 32 having a suitable universal joint 34, a rear or secondary differential assembly 36, and a pair of operable secondary or rear axles 38. Power is also provided to the secondary or rear drive train 30, each comprising a pair of secondary or rear tires and wheel assemblies 40.

  The above description relates to a vehicle in which the primary drive system 20 is disposed at the front of the vehicle and correspondingly the secondary drive system 30 is disposed at the rear of the vehicle. Called a car. As used herein, the expressions “primary” and “secondary” mean a drive system that always provides drive torque and a drive system that provides supplementary or intermittent torque, respectively. The present invention disclosed and claimed herein includes a primary drive train 20 disposed at the rear of the vehicle, and the components within the secondary drive train 30 and the secondary differential assembly 36 are vehicle components. These expressions (primary and secondary) are used in place of the expressions front and rear in this specification, as they are readily available with the car located at the front.

  Thus, the primary drivetrain 20 is located at the front of the car, the illustration of FIG. 1 is not limiting and is merely an example, and the components shown and the overall arrangement of the components are It should be understood that it is equally suitable for wheel drive vehicles and can be used with the primary rear wheel drive vehicle. In such a vehicle, the primary differential 24 is replaced with a secondary differential assembly 36 at the rear of the vehicle, and the secondary differential assembly 36 is replaced with the primary differential 24 in front of the vehicle. Will be moved to the department.

  A controller or microprocessor 50 that receives signals from a plurality of sensors and provides control functions, i.e., operating signals, to an electromagnetic clutch assembly 70 operatively disposed in front of the secondary differential assembly 36 is a vehicle drive train 10. Is related. Specifically, a first sensor such as variable reluctance or Hall effect sensor 52 detects the rotational speed of the primary (front) tire and wheel assembly 28 on the right side and provides an appropriate signal to the microprocessor 50. Similarly, a second variable reluctance or Hall effect sensor 54 senses the rotational speed of the left primary (front) tire and wheel assembly 28 and provides a signal to the microprocessor 50. A third variable reluctance or Hall effect sensor 56 senses the rotational speed of the right secondary (rear) tire and wheel assembly 40 and provides a signal to the microprocessor 50. Finally, a fourth variable reluctance or Hall effect sensor 58 associated with the left secondary (rear) tire and wheel assembly 40 senses its speed and provides a signal to the microprocessor 50. The speed sensors 52, 54, 56, 58 can be independent or dedicated sensors or sensors mounted on the car for use in anti-lock braking systems (ABS) or other speed sensing and control devices. Should be understood. Although not shown in FIG. 1, it should be understood that a conventional counting wheel or tone wheel is associated with each of the speed sensors 52, 54, 56, 58, as appropriate.

  The controller or microprocessor 50 can also receive information regarding the output speed of the transaxle 14. A variable reluctance or Hall effect sensor 62 associated with the tone wheel 64 of the front or primary propulsion shaft 22 can be utilized. In an alternative form, utilizing a variable reluctance or Hall effect sensor 66 associated with the secondary differential assembly 36 and disposed adjacent to the tone wheel 68 at the input shaft of the secondary differential assembly 36. You can also. The controller or microprocessor 50 receives signals from sensors 52, 54, 56, 58 and either sensor 62 or sensor 66 and adjusts the signals to determine corrective actions to improve vehicle stability, Software is included that maintains the control state of the vehicle and / or corrects or compensates for vehicle skid or other abnormal driving conditions and provides an output signal to the electromagnetic clutch assembly 70.

  Next, in FIG. 2, the electromagnetic clutch assembly 70 includes a continuous flange defining a plurality of through openings 76 or a cylindrical bell housing 72 having a plurality of ears or protrusions 74. The plurality of through openings 76 are adapted to accept, for example, threaded fasteners that facilitate attachment of the differential assembly 36 illustrated in FIG. 1 and disassembly from the housing. . The cylindrical housing 72 receives and supports a rolling bearing assembly such as a ball bearing assembly 78 that rotatably supports the bell-shaped input member 82. Input member 82 may include a short shaft 84 having a male spline 86. Other positive drive means such as keyways, hexagonal flats, etc. can also be defined by the input short shaft 84. A second rolling bearing assembly, such as a ball bearing assembly 88, rotatably supports a cylindrical output hub 92. The cylindrical inner wall of the input member 82 defines a plurality of female splines or gear teeth 94.

  A clutch ring or collar 96 is disposed radially between the cylindrical input member 82 and the cylindrical output hub 92, and the clutch ring or collar 96 is complementary to the female thread 102 on the inner surface of the input member 82. It has a male threaded portion 98 at the periphery that engages with the female threaded portion 102. Thus, as can be readily understood, the clutch wheel or collar 96 can be screwed into and removed from the input member 82 by appropriate relative rotation. A roller bearing assembly 104 is between the clutch wheel or collar 96 and the output hub 92. A fluid tight elastomeric seal 106 is received in a circumferential groove 108 formed in the inner surface of the clutch ring or collar 96 adjacent to the roller bearing assembly 104 and is fluid tight between the output hub 92 and the clutch collar 96. Providing a seal. An O-ring 112 received in the circumferential groove 114 of the clutch wheel or collar 96 also provides a seal between the outer surface of the clutch hub or collar 96 and the input member 82. The output shaft 120 preferably includes a male spline 122 that mates with the female spline 124 in the cylindrical output hub 92 and rotatably engages the female spline 124. A suitable oil seal 126 is disposed within the output hub 92 and maintains a fluid tight interior region within the generally cylindrical input member 82.

  Turning now to the friction clutch element itself, the electromagnetic clutch assembly 70 includes a first plurality of larger diameter clutch plates 132 having male or outer splines that engage the female splines 94 of the input member 82. A primary or pilot clutch pack 130 is provided. As described above, the friction clutch plate 132 having a larger diameter rotates together with the input member 82. A plurality of small-diameter clutch plates 134 are alternately arranged with the first plurality of large-diameter clutch plates 132, and the small-diameter clutch plates 134 have an inner side, that is, a female spline 136. The spline 136 engages a male spline 138 in the complementary form of a first circular member or plate 140 that is rotatably received by the cylindrical output hub 92. The first and second plurality of clutch plates 132, 134 include a suitable friction material disposed on at least one surface of each of the plates. The first circular plate 140 has a plurality of ramp-shaped recesses 142 arranged in a circular pattern around the axis of the output hub 92. The recess 142 defines a sloped portion of the helical torus. A load transfer ball 144 or similar load transfer member that rolls along an ramp defined by the slope of the recess 142 is disposed in each of the recesses 142. The large second circular member or plate 146 is disposed in opposing relation to the first circular plate 140 and has a plurality of similar recesses 148 that are of complementary dimensions and arrangement. doing. In this way, the load transmitting ball 144 is received and captured in a pair of opposing recesses 142, 148, the ends of the recesses 142, 148 are curved, and the interior region of the recesses 142, 148. This is a much steeper slope than this, so that the load transfer ball 144 is effectively trapped in the region defined thereby.

  Replacing the recesses 142, 148 and the load transmitting ball 144 with other similar mechanical elements that axially displace the circular plates 140, 146 in response to relative rotation between the circular plates 140, 146. It will be understood that this is possible. For example, it is possible to use tapered rollers arranged in a conical spiral shape in a complementary form.

  One important design consideration for the recesses 142, 148 and the load transfer ball 144 is that the geometry and overall design of the clutch assembly 70 and the clearance are self-engaging by the clutch assembly 70. ) To ensure that it does not. The electromagnetic clutch assembly 70 must not be self-engaged and must be able to adjust the friction clutch pack locking action in direct proportion to the input signal provided by the controller or microprocessor 50.

  The second circular plate 146 is complementary to the male spline or gear teeth 154 formed on the output hub 92 and engages with the gear teeth 154. have. A circular plate 156 having a spline 158 that engages the female spline 94 in the input member 82 is disposed between the first or pilot clutch pack 130 and the second circular member 146.

  There is an annular flat washer 160 on the side or surface of the first circular plate 140 opposite the second circular plate 146. On the opposite side of the flat washer 160 from the first circular plate 140 is a backup or support annular member 162 seated in the triangular circumferential groove 164 of the clutch collar 96.

  The flat washer 160 is preferably made of a plastic such as thermoplastic polyimide or similar material. For example, a plastic manufactured by Mitsubishi Chemical under the name Aurum JQC3025 and an engineered low mu polyimide plastic such as DuPont Vespel® are suitable. Both have been found to provide good performance. The plastic material must have a sufficiently high PV value so that it does not self-sacrifice under the load and speed conditions present in the specific application.

  The secondary or main friction pack assembly 170 is located between the second circular member 146 and the surface of the input member 82 extending radially and circumferentially. The main friction clutch pack assembly 170 includes a first plurality of large diameter clutch plates or disks 172 having male splines 174 that are drivably engaged with splines 94 formed on the input member 82. A second plurality of small diameter discs 176 having female splines 178 that engage with complementary forms of male splines 154 in the cylindrical output hub 92 become the first plurality of large diameter friction discs 172. On the other hand, they are bound together. Also in this case, the first and second plurality of clutch plates 172, 174 have a suitable friction material disposed on at least one surface of each of the plates.

  An electromagnetic coil 184 is disposed in a suitable recess 182 of the clutch collar 96. The electromagnetic coil 184 is connected to at least one electrical lead 186 that provides power from the controller or microprocessor 50.

  In operation, when electrical energy is applied to the electromagnetic coil 184, the plate 156 is drawn toward the clutch hub 96 and generates a resistance force that causes the first circular plate or member 140 to move to the second circular shape. Rotating relative to the plate or member 146, the load transmitting ball 144 rides into the recesses 142 and 148, thereby urging the plates or members 140 and 146 apart. The second member 146 functions as a force applying plate, and this axial movement compresses the main or secondary friction clutch pack and transmits torque between the input member 82 and the output shaft 120. The plain washer 160 amplifies or enhances the torque generated by the main or primary clutch pack 130.

The torque added from the friction surface of the plain washer 160 is a value obtained by multiplying the number of surfaces that can act on the vertical force applied to the surface, the friction coefficient of the friction surface, and the average radius of the friction surface. This torque is converted to an additional axial force equal to the additional torque from above divided by the pitch radius of the load transfer ball 144 and then divided by the tangent of the ball cam angle. From this, it can be understood that when the friction surface is pulled away from the ball cam and the load is increased, the load increases. This interactive process is called feedback action. However, it is necessary to avoid the degree of feedback action that causes the clutch assembly 70 to lock due to mathematical phenomena growing in an uncontrolled state. This growth is similar to that seen when the microphone is placed in front of the speaker when uncontrolled. A graph of this relationship applied to this device is shown in FIG. There are two solutions to deal with excess gain. One is to select the material to provide a friction surface with a low coefficient of friction (approximately 0.03 to 0.05). Another solution is to modify the ball slope angle to be about 16.5 °. Any of these modifications will typically provide controllability and certainty for changes in physical characteristics observed over time and temperature.
T _n = FR _n μ
here,
T _n = additional torque F = ball pulling force R _n = average radius of a single friction surface μ = dynamic coefficient of friction against the friction surface T = T _n + T _p
here,
T = total torque T _n = additional torque T _p = primary clutch torque

For this reason,

  Next, in FIG. 4, this graph provides information on how the electromagnetic clutch assembly 70 of the present invention provides an increased degree of torque amplification depending on the friction factor of the flat wheel or washer 160. For this reason, choosing a specific coefficient of friction for the material from which the plain washer or wheel 160 is made and taking into account the surface finish on its peripheral surface is the feedback action of the primary or secondary friction clutch pack 170 realized thereby and It will be appreciated that it is easy to select a specific amount of torque increase due to the improved fastening action.

  The above disclosure is the best mode devised by the inventors for carrying out the present invention. However, it will be apparent that devices embodying modifications and variations will be apparent to those skilled in the art of electromagnetic clutch assemblies. The foregoing disclosure represents the best mode contemplated by the inventors for carrying out the invention and is intended to enable those skilled in the relevant art to practice the invention. The invention is not to be limited thereby, but is to be construed as including such obvious modifications as described above and only as limited by the spirit and scope of the appended claims.

1 is a schematic diagram of a power train of a four wheel drive vehicle having an electromagnetic clutch assembly according to the present invention utilized with a rear differential. FIG. 1 is a complete cross-sectional view of an electromagnetic clutch assembly according to the present invention. FIG. 3 is an exploded view of a flat pattern of a ball ramp actuator of an electromagnetic clutch assembly according to the present invention along line 3-3 of FIG. 6 is a graph showing the degree of torque amplification provided by the electromagnetic clutch assembly mechanism according to the present invention;

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Drive train of 4 wheel drive vehicle 12 Motor | power_engine 14 Transaxle 16 Bevel gear / twisted bevel gear set 20 Primary drive system 22 Primary propulsion shaft 24 Primary differential 26 Front axle 28 Primary tire and wheel assembly / left primary (front) Tire and wheel assembly 30 Secondary drive system 32 Secondary propulsion shaft 34 Universal joint 36 Secondary differential assembly 38 Secondary or rear wheel shaft 40 Secondary or rear tire and wheel assembly / right secondary (rear) tire And wheel assembly 50 controller or microprocessor 52 first variable reluctance or Hall effect sensor / speed sensor 54 second variable reluctance or Hall effect sensor / speed sensor 56 second variable reluctance or Hall effect sensor / speed sensor 58 first Two variable reluctance or Hall effect sensors / speed sensors 6 Variable reluctance or Hall effect sensor 64 Tone wheel 66 Variable reluctance or Hall effect sensor 68 Tone wheel 70 Electromagnetic clutch assembly 72 Bell-shaped housing 74 Ear-shaped protrusion 76 Through-opening 78 Ball bearing assembly 82 Bell-shaped input member / cylindrical input Member 84 Input short shaft 86 Male spline 88 Ball bearing assembly 92 Cylindrical output hub 94 Female spline or gear tooth 96 Clutch ring or collar / clutch hub 98 Male thread 102 Female thread 104 Roller bearing assembly 106 Elastomeric seal 108 Circumferential groove 120 Output shaft 122 Male spline 124 Female spline 126 Oil seal 130 Primary or pilot clutch pack 132 Friction clutch plate / large diameter clutch plate / first clutch plate 134 small Clutch plate / second clutch plate 136 Inside or female spline 138 Male spline 140 First circular member or plate 142 Recess 144 Load transmitting ball 146 Large diameter second circular member or plate 148 Recess 152 Female spline or gear teeth 154 Male spline or gear teeth 156 Circular plate 158 Spline 160 Plain washer 170 Secondary or main friction pack assembly 172 First plurality of large diameter clutch plates or discs 174 Male spline / Clutch plate 176 Second plurality of small diameter discs 178 Female spline 184 Electromagnetic coil 186 Electrical conductor

Claims (20)

In the electromagnetic clutch assembly,
An input member and an output member arranged coaxially;
A first circular member having a plurality of camming surfaces; and an output member adjacent to the first circular member, having a plurality of similar camming surfaces and capable of rotating with the output member. A second circular member splined;
A plurality of similar load transmitting balls disposed on the camming surface;
A friction washer disposed between the first circular member and the input member;
A first clutch having a first plurality of first clutch plates splined to the first circular member and a second plurality of pointed first clutch plates splined to the input member. Pack,
An electromagnetic coil for engaging the first clutch pack;
A first plurality of second clutch plates splined to the input member and a second clutch pack having a second plurality of inserted second clutch plates splined to the output member An electromagnetic clutch assembly.   2. The electromagnetic clutch assembly according to claim 1, further comprising an outer housing adapted to receive the input member and a friction preventing bearing rotatably supporting the input member within the outer housing. .   2. The electromagnetic clutch assembly of claim 1, wherein the output member defines a splined passage and is complementary to the splined passage of the output member. An electromagnetic clutch assembly further comprising an output shaft having.   The electromagnetic clutch assembly of claim 1, wherein the friction washer is made of plastic.   2. The electromagnetic clutch assembly according to claim 1, further comprising a plurality of oil seals for sealing an inner region of the clutch assembly that houses the first and second clutch packs.   The electromagnetic clutch assembly of claim 1, wherein the friction washer provides a controlled feedback action that improves the torque handling capability of the second friction clutch pack.   The electromagnetic clutch assembly of claim 1, wherein the washer is made of thermoplastic polyimide. In the torque transmission device having a pair of clutches,
A rotatable input member;
A rotatable output member;
A main clutch having a first plurality of clutch plates connected to the input member and a second plurality of clutch plates alternately arranged with the first plurality of clutch plates and connected to the output member;
A cam actuator having first and second members defining opposing cam surfaces and coupled to the output member such that the first cam member can rotate with the output member;
The first plurality of clutch plates connected to the input member and the second plurality of clutch plates alternately arranged with the first plurality of clutch plates and connected to the second member of the cam actuator A pilot clutch having
An electromagnetic coil for engaging the pilot clutch;
A torque transmission device comprising a combination of a friction washer that is operatively disposed between the second member of the cam actuator and the input member.   9. The torque transmission device according to claim 8, further comprising an outer housing assembly adapted to receive the input member, and a friction preventing bearing rotatably supporting the input member within the outer housing. .   9. The torque transmission device according to claim 8, wherein the output member defines an internal passage in which a spline is provided and is complementary to a passage in the output member in which the spline is provided. A torque transmission device further comprising: an output shaft having:   The torque transmission device according to claim 8, wherein the friction washer is made of plastic.   9. The torque transmission device according to claim 8, wherein the friction washer provides a feedback action that is controlled to improve the torque handling capacity of the friction clutch pack of the main clutch.   9. The torque transmission device according to claim 8, wherein the washer is made of thermoplastic polyimide.   The torque transmission device according to claim 8, further comprising a plurality of oil seals for sealing an inner region of the torque transmission device that houses the first and second clutch packs. In the electromagnetic clutch assembly,
An input member and an output member arranged coaxially and rotatable;
An electromagnetic coil;
A first cam member disposed around the output member;
A second cam member splined with the output member so that it can rotate with the output member;
A washer disposed between the first cam member and the input member;
A primary friction clutch having a first plurality of primary clutch plates splined to the first cam and a second plurality of inserted primary clutch plates splined to the input member;
A combination of a first plurality of secondary clutch plates splined to the input member and a second clutch having a second plurality of inserted secondary clutch plates splined to the output member. Clutch assembly.   16. The electromagnetic clutch assembly of claim 15 further comprising an outer housing adapted to receive the input member and a rolling bearing assembly that rotatably supports the input member within the outer housing. Solid.   16. The electromagnetic clutch assembly of claim 15, wherein the output member defines a splined surface that defines a hole provided with a spline and is complementary to the hole provided with the spline of the output member. An electromagnetic clutch assembly further comprising an output shaft having.   The electromagnetic clutch assembly of claim 15, wherein the washer is made of plastic.   The electromagnetic clutch assembly of claim 15, wherein the washer is made of thermoplastic polyimide. 16. The electromagnetic clutch assembly of claim 15, wherein the means for axially pulling the cam member apart from a plurality of opposing surfaces of arcuate recesses disposed in the cam member and the recesses disposed in the recess. A plurality of load transmission members.

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