WO2003033929A1

WO2003033929A1 - Electrical mechanical disc clutch unit

Info

Publication number: WO2003033929A1
Application number: PCT/NL2002/000664
Authority: WO
Inventors: Hendrikus Jan Kapaan; Cornelius Petrus Antonius Vissers; Jacobus Zwarts; Emmanuel Jacques Eyroud
Original assignee: Ab Skf
Priority date: 2001-10-19
Filing date: 2002-10-18
Publication date: 2003-04-24

Abstract

A disc clutch unit, comprises a rotatable body (1), a concentric rotatable member (2), and a disc clutch. Said disc clutch comprising a disc (4) connected to the rotatable body or the rotatable member and friction means (5) which enclose the disc at both disc surfaces. The friction means being connected to the other of the rotatable body and the rotatable member and being operative between a clamped state in which the disc surfaces (6,7) and the friction means frictionally engage each other so as to establish a slipping or fixed relationship and a free state in which the disc surfaces and the friction means are freely rotatable with respect to each other.

Description

Electrical mechanical disc clutch unit

The invention is related to the field of clutches. A clutch usually comprises friction plates which are held pressed against each other, e.g. by means of a disc spring. By depressing the spring, the pressure is relieved and the clutch is disengaged.

The spring in question may be actuated either mechanically, e.g. by a lever hydraulically, or electrically. The electric actuation can be obtained through, for instance, an electrically driven screw actuator.

The prior art clutches rely on the preload which is provided by an axial disc spring on a flat friction plate. Although such spring usually performs satisfactorily, it still has disadvantages. For instance, the preload and thereby the torque to be transmitted has a fixed maximum and can not be influenced. This is caused by the fact that in the case of prior art clutches, the friction plate engages one surface of the clutch. A further consequence thereof is that the plates should have a relatively large diameter in order to provide the required torque output. Also a worn clutch has to be adjusted manually.

The object of the invention is to provide an improved clutch device. This object is achieved by a disc clutch unit, comprising a rotatable body which can be connected to a drive source, a concentric rotatable member which can be connected to a driven shaft, and a disc clutch comprising a disc connected to the output member and friction means which enclose the disc at both disc surfaces, said friction means being connected to the other of the rotatable body and the rotatable member and being operative between a clamped state in which the disc surfaces and the friction means frictionally engage each other so as to establish a slipping or fixed relationship and a free state in which the disc surfaces and the friction means are freely rotatable with respect to each other, characterized in that the rotatable body is accommodated in a housing which can be connected to the stationary part of the drive source, the outer circumference of the body being provided with (part of) a starter means.

The disc clutch unit according to the invention has a friction means which pinches the disc from both sides. Thereby, first of all a considerable torque can be transmitted, even in the case of a disc of limited diameter. Moreover, the internal forces in the clutch remain limited, as the pinching forces are directly equilibrated through the friction means at both sides. As a result of the high pinching force, a considerable torque can be transmitted even in the case of a disc of moderate diameter. This system ensures an automatic wear compensation for the clutch pads and clutch disc.

The rotatable body may carry axially oriented compression springs which are regularly spaced in the circumferential direction of said body, a bracket member which lies opposite said compression springs, and friction pads which are positioned between said springs and bracket member, the disc being pinched between the springs, bracket member and friction pads, and actuator means for influencing the pinch force exerted on the disc.

The compression springs, consisting of steel spring or resilient materiel e.g. rubber, provide the state force required for pressing the f iction pads onto the disc. The spring force delivered by said springs is sufficient for obtaining a slip-free state. The actuator means act to counteract the spring force, such that a slipping state or a freely rotatable state can be accurately controlled.

The actuator may either directly engage the friction pads, or indirectly through a ringshaped pressure plate.

The actuator, e.g. screw actuator, may be driven by a common electric motor which is concentric to the rotatable body, and the screw actuators engage said motor through a mechanical transmission. Said transmission may comprise gears, chains or toothed belts. The bracket member is divided in at least two adjoining halves so as to facilitate removal thereof with the aim of friction pad replacement.

The starter means comprise an integrated starter-generator unit. Said starter means comprise a toothing for engagement with the drive gear of a starter motor.

The rotatable body comprises two concentric rings which are rotatably supported with respect to each other through a rolling element bearing means, one of said rings being provided with starter means, and the other of said rings being connected to the disc clutch, said rings being held in a preloaded position with respect to each other through essentially tangentially oriented springs for damping vibrational forces during start and service conditions. One of the rings is fitted around the other one, and their facing cylindrical surfaces being provided with at least one raceway, two sets of rolling elements being provided which each are in rolling contact with opposite raceways, the rotatable body also acts as a flywheel due to its mass. Although the friction means may be carried out in several ways, preferably they comprise at least one calliper carrying two opposite friction pads between which the disc is accommodated, as well as the drive means for moving the friction pads towards and from each other. Preferably, the disc is slidable with respect to the torque members so as to compensate for wear of disc and pads. This can e.g. be obtained by means of a splined shaft torque member.

The drive means may comprise an electromagnet, said electromagnet maintaining the clamping state of the friction means when the energy is switched off after a predetermined period of time. A stable embodiment can be obtained in case the friction means comprise at least two clutch callipers which are equally spaced over the circumference of the disc. Nevertheless, it is also possible to apply a single clutch calliper in combination with appropriate balancing devices e.g. adding balancing weight on the unit (static) or using a defined number of balls moving in a raceway at the circumference of the unit, in order to create optimal balancing conditions.

The invention is also related to a hybrid power train, comprising an internal combustion engine, an electric motor and a transmission for connecting to a driveable component, e.g. the driven wheels of a vehicle, said combustion engine and electric motor engaging each other through a first clutch device, and said electric motor and transmission engaging each other through a second clutch device. According to the invention at least one of the first and second clutch device is a clutch device as described before.

Such a power train for hybrid automotive applications is known. The electric motor in question can be constituted by a so-called integrated starter-generator. In that case, both the starter and the generator are a part of a single device. Alternatively, a separate electric motor can be provided which is energised by the starter-generator. Also, the starter-generator can charge the battery backup of a hybrid power train.

The transmission can be electrically actuated. Furthermore, the transmission can be an automatic transmission e.g. continuously variable transmission or a gear shift transmission. Said transmission can be selectively actuated by the internal combustion engine or the electric motor.

The invention will further be described with reference to an embodiment shown in the figures. Fig. 1 shows a view in perspective and partially cut away of an electric mechanical clutch unit according to the invention.

Fig. 2 shows a vertical cross section to the axes of the clutch unit according to fig. 2. Fig. 3 shows a first hybrid power train comprising the clutch unit according to the invention.

Fig. 4 shows a second hybrid power train. Fig. 5 shows a second embodiment of the clutch unit.

The clutch unit shown in figures 1 and 2 comprises a rotatable body 1, which can be connected to e.g. the internal combustion motor of a vehicle. By means of a disc clutch 3, said rotatable body 1 can be connected to, or discomiected from an output member 2, which can e.g. be connected to a gear box or continuously variable transmission.

The disc clutch 3 comprises a disc 4 comiected to the output member 2, as well as pairs of opposite friction pads 10. One friction pad 10 of each pair is connected to a bracket member 9, the other friction pad 10 of each pair is connected to a ringshaped pressure plate 13. According to a particular embodiment, the clutch disc is flexibly comiected with the output member using metallic or non-metallic means in order to compensate for misalignment between the rotatable body (input member) and the output member.

As is clear from fig. 1, said ringshaped pressure plate 13 is permanently biased by compression springs 8, which are accommodated in blind holes 26 of the ring 19 of the rotatable body 1. Thus, the springs 8 firmly compress the friction pad 10 into an engagement with the opposite services 6, 7 of the disc 4. The biasing force of the springs 8 is selected such that a non-slipping relationship is obtained between the friction pads 10 and the disc 4.

Furthermore, screw actuators 12 are accommodated in the ring 19 of the rotatable body 1. Said screw actuators are accommodated in the throughgoing bores 27 of said ring 19. At the one end, by means of bolts 27, the screw actuators 12 are connected to the ringshaped pressure plate 13. At their other end, the screw actuators carry a gear 28, which each engage a pinion 15. This pinion 15 in turn is connected to the shaft 29 of an electric motor 14 which is accommodated in a central hole 30 of the ring 19. By means of slipring ( contacting or non-contacting) energy transfer devices feed the electric motor 14 with electric current so as to control the screw actuators 12 and so as to transfer sensor signals.

In this way, by means of the screw actuators the biasing force of the compression springs 8 can be counteracted. In other words, the force by means of which the ringshaped pressure plate 13 presses the disc 4 and the friction pads 10 upon each other can be varied so as to obtain a slipping engagement there between or even a freely rotatable condition.

The rotatable body 1 has, besides the inner ring 19, an outer ring 18. These rings 18, 19 are supported with respect to each other by means of the bearing 20, which comprises a double set of deep groove ball bearings 23, 24. These bearings are accommodated in the facing cylindrical surfaces 21, 22 of the rings 18, 19.

As shown in fig. 1 and 2 essentially tangentially oriented springs 20 are accommodated in the recesses 31 between the rings 18, 19. By means of end caps 35, these springs 20 are supported at their ends against the end surfaces 32, 34, which delimit the recesses 31 in respectively the outer ring 18 and the inner ring 19. Thereby, these springs 20 can absorb the shock or vibration forces which occur during service and also during start conditions. In this respect, the outer ring 18 is provided with an integrated starter generator unit 17. The rotatable body 1 acts as a flywheel. The clutch unit contains one or more lockpins to block the movement of the spring/pressure plate when the spring is in compressed condition.

The electric mechanical clutch unit shown in fig. 3 comprises a rotatable input shaft 2, onto which a disc 4 is connected. The disc 4 is straddled by means of two friction means 5 which are equally spaced along the circumference of the disc 4. The friction means 5 carry two opposite friction pads 10 each, containing callipers 50. The callipers 50 are connected to a bracket 9 which in turn is connected to the rotatable body 1. The rotatable body is connected to the output shaft 51.

The friction pads 10 are moveable towards and away from each other by means of an electric motor 14 and a screw mechanism 11, which components are known per se. By actuating the electric motors 14, the friction pads 10 of the two friction means 5 exert a pinching force on the disc 4. Depending on the magnitude of this pinching force, a fixed or slipping connection between the input shaft 2 and the output shaft 51 is obtained. An autobalancing ring 25 is provided for balancing the clutch unit

The electric mechanic clutch unit according to the invention can be applied in industrial and automotive (hybrid) power trains. A first example of a hybrid power train containing two electric mechanical clutches 40 according to the invention is shown in fig. 4. One electric mechanical clutch 40 is positioned between the internal combustion engine 41 and the integrated starter-generator 38. This integrated starter-generator is connected to the battery 42 through the inverter 43.

The other electric mechanical clutch 40 according to the invention is positioned between the integrated starter-generator 38 and the continuously variable transmission 44, which in turn is connected to the vehicle shaft 45 and the vehicle wheels 46. Said electric mechanical clutch can also be integrated with the starter-generator. The integrated starter-generator performs both as a starter motor as well as generator. Moreover it can function as a damper and can provide reverse driving of the vehicle when changing direction of rotation. In the second embodiment of a hybrid power train as shown in fig. 5 gear transmission 47 is applied. A slip ring may be integrated in the electric mechanical clutch or in the starter-generator for activating the rotating electric motor of the clutch.

The disc 4 can be made of a metallic, non-metallic or a composite material, e.g. a ceramic material. The clutch calliper can be connected to either the torque input member or the torque output member. For ease of maintenance, the friction pads are moveable in radial direction with respect to the disc, e.g. for changing worn out pads. Thus, pad removal and replacement can take place without needing the separation of transmission and engine.

The clutch unit may furthermore contain one or more lockpins to block the movement of the springs and pressure plate with the spring in compressed condition. This is an important safety aspect when changing worn out clutch pads.

The springs 18, 19 of the body 1 may contain steel springs or other non-metallic resilient components, e.g. a rubber pad or spring or a combination thereof.

The clutch unit may furthermore comprise sensors for controlling the number of rotations, load, temperature, etc. The starter generator may be air-cooled or liquid- cooled.

The clutch unit furthermore has a housing which contains the drive section, damper function, actuating and control means, etc. The clutch parts themselves, in particular the friction pads 10, protrude out of the housing so as to allow easy changing of worn out clutch pads after removing the bracket.

The clutch disc surface may contain a high friction coating. Important features of the clutch unit include amongst others a self-contained actuator thereof incorporating drive units, clutch and control units. The transmission is fit for high torques. The control from fixed to idle running conditions can be electronic. Furthermore, automatic compensation of clutch disc or pad wear is insured. Misalignment between drive and driven sections is compensated for. E.g. a clutch disc is flexibly connected to the drive means using metallic or non-metallic means in order to compensate for misalignment between the drive and driven sections. A clutch unit can be applied for automotive and industrial applications, e.g. manual and automatic transmissions, combinations with starter generator and hybrid power trains.

The components of the clutch unit, such as disc, pads, housing, etc. can be made of metallic or non-metallic material, e.g. sheet metal or plastic, cast iron or metal powder material, composite material; furthermore, coatings may be applied to decrease or increase frictional characteristics.

Manufacturing methods and operations may include forging, stamping, moulding, energy welding, gluing, milling, hard turning, whirling, grinding, etc.

Claims

1. Disc clutch unit, comprising a rotatable body (1) which can be connected to a drive source, a concentric rotatable member (2) which can be connected to a driven shaft, and a disc clutch (3) comprising a disc (4) connected to the output member (2) and friction means (5) which enclose the disc (4) at both disc surfaces (6, 7), said friction means (5) being connected to the other of the rotatable body (1) and the rotatable member (2) and being operative between a clamped state in which the disc surfaces (6, 7) and the friction means (5) frictionally engage each other so as to establish a slipping or fixed relationship and a free state in which the disc surfaces (6, 7) and the friction means (5) are freely rotatable with respect to each other, characterized in that the rotatable body (1) is accommodated in a housing (16) which can be connected to the stationary part of the drive source, the outer circumference of the body (1) being provided with (part of) a starter means (17).

2. Clutch unit according to claim 1, wherein the rotatable body (1) carries axially oriented compression springs (8) which are regularly spaced in the circumferential direction of said body (1), a bracket member (9) which lies opposite said compression springs (8), and friction pads (10) which are positioned between said springs (8) and bracket member (9), the disc (4) being pinched between the springs (8), bracket member (9) and friction pads (8), and actuator means (11) for influencing the pinch force exerted on the disc (4).

3. Clutch unit according to claim 2, wherein the actuator means (11) comprise screw actuators (12) which are regularly spaced in the circumferential direction of the rotatable body (1).

4. Clutch unit according to claim 3, wherein the screw actuators (12) engage the friction pads (10).

5. Clutch unit according to claim 3, wherein the screw actuator (12) engage a ringshaped pressure plate (13) which in turn engages the friction pads (10).

6. Clutch unit according to any of claims 3-5, wherein the screw actuators (12) are directly or indirectly drivable by means of an electric motor (14), e.g. a permanent magnet motor or brush motor.

7. Clutch unit according to claim 6, wherein the electric motor (14) is concentric to the rotatable body (1), and the screw actuators (12) engage said motor through a mechanical transmission (15).

8. Clutch unit according to claim 7, wherein the transmission comprises gears or chains.

9. Clutch unit according to claim 7, wherein the transmission comprises pulleys and belts.

10. Clutch unit according to any of claims 2-9, wherein the fiiction pads (10) are positioned on both disc surfaces (6, 7).

11. Clutch unit according to any of claims 2-10, wherein the bracket member (9) is divided in at least two adjoining halves so as to facilitate removal thereof with the aim of friction pad replacement.

12. Clutch unit according to any of the preceding claims, wherein the starter means comprise an integrated starter-generator unit (17).

13. Clutch unit according to any of the preceding claims, wherein the starter means comprise a toothing for engagement with the drive gear of a starter motor.

14. Clutch unit according to any of the preceding claims, wherein the rotatable body (1) comprises two concentric rings (18, 19) which are rotatably supported with respect to each other through a rolling element bearing means (31), one (18) of said rings being provided with starter means (17), and the other (19) of said rings being connected to the disc clutch (3), said rings (18, 19) being held in a preloaded position with respect to each other through essentially tangentially oriented springs (20) for damping vibrational forces during start and service conditions.

15. Clutch unit according to claim 14, wherein one (18) of the rings is fitted around the other one (19), and their facing cylindrical surfaces (21, 22) being provided with at least one raceway (23, 24), at least one set of rolling elements being provided which each are in rolling contact with opposite raceways (23, 24).

16. Clutch unit according to any of the preceding claims, wherein the unit carries a static or dynamic balancing unit.

17. Clutch unit according to claim 16, wherein the rotatable body (1) carries an autobalancing ring unit (25), with balls running raceway.

18. Clutch unit according to any of the preceding claims wherein the friction means (5) comprise at least one calliper.

19. Power train, comprising an internal combustion engine (17) and a transmission (19, 22) for connecting to a driveable component, e.g. the driven wheels (21) of a vehicle, said internal combustion engine (17) and said transmission (19, 21) engaging each other through a clutch device, characterised by a clutch device according to any of claims 1 - 18.

20. Power train, comprising an internal combustion engine (17), an electric motor (13) and a transmission (19, 22) for connecting to a driveable component, e.g. the driven wheels (21) of a vehicle, said combustion engine (17) and electric motor (13) engaging each other through a first clutch device (15), and said electric motor (13) and transmission (19) engaging each other through a second clutch device (16), characterised in that at least one of the first (15) and second (16) clutch device is al clutch device according to any of claims 1 -18.

21. Power train according to claim 20, wherein the electric motor is constituted by an integrated starter-generator (13).

22. Power train according to any of claims 19 - 21, wherein the transmission (19, 22) is electrically actuated.

23. Power train according to any of claims 19 - 21, wherein the transmission is a continuously variable transmission (19).

24. Hybrid power train according to any of claims 19 - 21, wherein the transmission is a gear transmission (22).

25. Power train according to any of claims 19 - 21, wherein the fransmission is an infinitively variable transmission.