EP1000265A1

EP1000265A1 - Positive clutch

Info

Publication number: EP1000265A1
Application number: EP98938712A
Authority: EP
Inventors: Ünal GAZYAKAN; Gerhard Bailly; Detlef Baasch
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1997-08-04
Filing date: 1998-07-29
Publication date: 2000-05-17
Also published as: JP2001512811A; DE19733673A1; WO1999008015A1

Abstract

The invention relates to a positive clutch comprising a sleeve carrier (8), which is rotationally fixed to a component (1) that is to be coupled, and a sliding sleeve (9) which is made from a driving ring (10) and a gear shift hub (12) connected to each other by means of a sliding clutch (14). The driving ring (10) co-operates with a driver (15) which is rotationally fixed to a second component (2,3) that is to be coupled. The gear shift hub (12) is also rotationally fixed to the sleeve carrier (8) but is axially displaceable and co-operates with a coupling body (5) which is rotationally fixed to the second component (2,3) to be coupled. In order to minimise the breakaway torque of the sliding clutch and synchronisation torque during conditions of operation, the invention is characterised in that the sliding clutch (14) is a hydraulic clutch wherein torque is transmitted by a viscous medium.

Description

Positive clutch

The invention relates to a positive clutch with the features according to the preamble of claim 1.

In manual transmissions that are switched with traction interruption, d. That is, that an input shaft is separated from a prime mover during the switching process by a clutch, you can engage the respective gear with a clutch of the type described above, by pushing a shift toothing of a sliding sleeve into a clutch toothing of a clutch body, which is on a clutch to be coupled Gear element is attached, for. B. on a gear or gear housing. The torque in the switched state is transferred from one gear element via the clutch body, the clutch teeth, the gear teeth, the sliding sleeve and a sleeve carrier to another gear element, e.g. B. a gear or a shaft, transmitted or supported on the gear housing. The sleeve carrier can be a synchronizer body lying in the sliding sleeve or an outside guide ring which is fastened to the other gear element and to which the sliding sleeve is axially displaceably connected by means of driving teeth. The driving toothing can simultaneously perform another function, in particular it can be designed as a switching toothing or a running toothing.

The shifted gear determines the gear ratio and thus the speed ratio between the input shaft and an output shaft of the transmission. The non-coupled gear elements, e.g. B. free circulation, constantly engaged gears, the other gears run at a differential speed corresponding to their ratio to the switched gear elements. If changing from one gear to another, the parts to be coupled must be brought to approximately the same speed during shifting before the gear teeth of the sliding sleeve can engage in the gear teeth of the clutch body to be engaged.

A synchronization device is used for this. It usually consists of friction surfaces, e.g. B. a friction cone or lining plates, which are non-rotatably connected to the gear elements to be switched via plate carriers and form a slip clutch. When the sliding sleeve is axially displaced, the slip clutch is activated until the gear elements to be coupled are at least approximately synchronized.

A shift clutch is known from EP 0 184 077 B1, specifically for gearboxes in countershaft construction. A sliding sleeve is slidably arranged on an inner synchronizer body. The friction surfaces are in the form of a friction cone on the clutch body and a counter cone on a synchronizer ring which rotates with the sliding sleeve; the synchronizer ring can rotate between two stops relative to the sliding sleeve by a limited angle of rotation so that a locking device is brought into the locking position, for. B. a locking toothing on the synchronizer ring.

If you move the sliding sleeve in the direction of the clutch body to be switched, the synchronizer ring with its counter-cone is pressed against the friction cone of the clutch body via flexible locking means. The syn- chronring relative to the sliding sleeve, so that front oblique surfaces of the gear teeth meet corresponding locking surfaces of the locking teeth. As a result, an axial force is exerted on the synchronizing ring and the friction surfaces. The switching force simultaneously generates a restoring force on the synchronizer ring via the inclined surfaces. When the parts are synchronized, this outweighs the circumferential force acting on the friction surfaces and brings the synchronizer ring into a central position in which the sliding sleeve can be switched through. As soon as the locking surfaces release the switching path, no more axial force is transferred to the synchronizer ring and the slip clutch is released. When the sliding sleeve is shifted forward, the shift toothing is aligned with the toothing by its beveled surfaces and corresponding beveled surfaces on the toothing, resistance forces opposing the shifting force being overcome by the inert masses of the components to be rotated and by dragging moments of the lubricants and coolants.

From DE 195 06 987 AI a generic, positive clutch is known, the sliding sleeve of an outer driver ring, which engages a shift fork, and a shift hub, which is rotatably but axially displaceably arranged on a synchronizer body. The gearshift hub has a gear toothing which has end faces lying in a rotating surface and cooperates with a coupling toothing on a clutch body, the end faces of which also lie in a rotating surface. The coupling body is non-rotatably but axially elastically resiliently connected to a gear wheel which is rotatably mounted on a gear shaft. A slip clutch in the form of a spring-loaded clutch plate clutch is arranged between the synchronizer body, which is non-rotatably connected to the transmission shaft, and the driver ring, the driver ring serving as the outer disk carrier and the shift hub as the inner disk carrier. Lids are attached to the front of the shift hub, which run with little radial play to the driving ring and between which the lining plates are supported under the pressure of a corrugated spring.

The driver ring has on its outer circumference a single-toothing which cooperates with a driver toothing of a driver which is connected to the gearwheel in a rotationally fixed but axially resilient manner. The teeth of the driver toothing are narrower than the tooth gaps, so that an ample play is formed in the circumferential direction, which facilitates the engagement of the single-toothing during switching. The end faces of the driver toothing and the single-track toothing lie in a conical rotational surface, so that they form an angle in the axial direction to the peripheral surface and to the end face.

If the sliding sleeve is shifted from its neutral position in the direction of the switching position, the single-toothing of the driver ring comes into contact and engages with the driver teeth of the driver, so that a torque is transmitted from the gearwheel to the gear shaft via the lining plates. This torque depends on the force of the wave spring. It is decisive for the time it takes to establish synchronism between the gear and the gear shaft. Locking surfaces on the driver toothing prevent the switching toothing of the hub part from coming into contact with the crown toothing, before the gear and the gear shaft are nearly synchronized.

The end faces of the driver toothing, the single-toothing toothing, the coupling toothing and the shift toothing, which run in rotating surfaces, ensure that the torques generated by the gear elements to be coupled do not exert any reaction forces on the switching force. Furthermore, contact impacts on the driver teeth and coupling teeth are absorbed softly, and this results in a relatively uniform shifting force over the entire shift travel, which improves shifting comfort.

Since the lining plates of the slip clutch adhere to each other before shifting, there is static friction between them, which can transmit a much greater torque than sliding friction. If the driving toothing is now switched, a large moment corresponding to the static friction is first transmitted, which drops to a much smaller sliding friction torque when the lining plates move relative to one another. Such peak moments are undesirable because of the high component load, wear, noise and the heating of the components.

The invention has for its object to build up the synchronous torque more slowly in a clutch of the type mentioned and to control and regulate by operating parameters.

It is solved according to the invention by the features of claim 1. Further refinements result from the subclaims. According to the invention, a fluid clutch is used as the slip clutch, in which the torque is transmitted via a viscous means. Volumetric pumps, centrifugal pumps or viscous couplings can be used as the liquid coupling. First of all, they require a low starting torque, which is essentially determined by the masses of the fluid coupling to be accelerated. The drag torque and flow resistance, through which the torque is transmitted from the drive ring to the gear hub, only take effect with increasing speed difference.

A viscous coupling is characterized in that rotating surfaces move with little play relative to one another in a space filled with liquid, the transmissible torque being essentially determined by the viscosity of the liquid and the distance between the surfaces.

The pumps, which can be of different types, convey the liquid from a pressure side via a flow resistance to a suction side. The transmissible torque is essentially dependent on the size of the flow resistance, which results on the one hand from its geometric design and on the other hand from the viscosity of the liquid. Since the viscosity of the liquid changes with temperature, it is advisable to design the flow resistance as a variable throttle point. As a result, temperature influences can be compensated and desired characteristics for the transmissible torque for upshifts and downshifts can be controlled or regulated differently. The flow resistance can be controlled or regulated as a function of a rotational speed of a component or a rotational speed difference between two components or an nth derivative of the rotational speed according to time, where n can take any integer value. The speeds of the components of the slip clutch are particularly suitable for this. A simple speed control can be achieved by designing the flow resistance as a centrifugal valve. This detects the speed of the component and controls the flow resistance at the same time. However, it is also possible to record the speed separately and to control a controllable valve according to predetermined characteristic curves or characteristic fields via an electronic evaluation unit.

In addition to a speed-dependent control of the flow resistance, a temperature-dependent control is expedient, which can be used alone or in combination with the speed-dependent control. Component, equipment or ambient temperatures or their temperature gradients can be used for control. Since the heat transfer processes always take place with considerable delays, the use of temperature gradients is suitable for fast control or regulation. Simple control devices can be achieved with standard thermostatic valves, and more complex control methods use electronic aids and evaluation devices.

Simple regulating and control methods also result from the fact that the flow resistance is controlled or regulated as a function of a predetermined period of time over a time course. The timing can be started depending on the switching path or another suitable event. An internal gear pump can also be used as a slip clutch. It is simple in construction and reliable and can easily be accommodated in the given installation space. The internal gear pump expediently has planet gears mounted in a planet carrier, which mesh with a ring gear attached to the driving ring and are located in a space filled with liquid. Gear oil is usually used as the liquid. The planet gears convey the liquid from a suction side to a pressure side, which are connected to the suction side of an adjacent planet gear via design gaps. The gaps form flow resistances and are dimensioned accordingly for the torques to be transmitted.

According to a further embodiment, the suction side of a planet gear can be connected to the pressure side of another planet gear via a connecting channel. The other planet gear is expediently an adjacent planet gear, but this is not absolutely necessary. The flow resistance is expediently arranged in the connection channel or the connection channel itself is designed to be a flow resistance. The flow resistance in the connecting channel is expediently formed by a rotary slide valve or axial slide valve, which can be controlled or regulated by means of appropriate adjusting means depending on the parameters mentioned above or characteristic values derived therefrom.

Numerous features are shown and described in connection in the description and in the claims. The person skilled in the art will expediently also combine the features individually in the sense of the tasks to be solved consider and combine them into meaningful further combinations.

Exemplary embodiments of the invention are shown in the drawing. Show it:

1 shows a longitudinal section through a clutch according to the invention,

Fig. 2 shows a cross section along the line II-II in Fig. 1 and

3 shows a cross section of a variant of FIG. 2.

On a gear shaft 1, two gears 2 and 3 are mounted by means of bearings 4, preferably needle bearings. The clutch is arranged between the gears 2 and 3. It is designed as a double filling and is therefore essentially symmetrical. Because of the comprehensibility of the description and the clarity of the drawing, components that occur several times are provided with the same code number or only identified once.

The clutch has a sliding sleeve 9, which is constructed from a drive ring 10 and a shift hub 12, which are connected to one another via a slip clutch 14 in the form of an internal gear pump. The slip clutch 14 comprises a ring gear 22, which is integrally connected to the driving ring 10, but can also be designed as a separate component, planet gears 24, which are mounted in a planet carrier 23 and cover 27, which with the Shift hub 12 are firmly connected and form an oil-filled and sealed by means of seals 28 with this and the driving ring 10.

The planet gears 24 are mounted with their teeth directly in recesses 26 of the planet carrier 23 and mesh with the ring gear 22. To save weight, they have holes 25. The planet carrier 23 is rotatably connected to the gear hub 12. As a result, the planet gears 24 form small gear pumps with the ring gear 22, the pressure sides 30 of which are connected to suction sides 29 of adjacent planet gears via appropriately dimensioned gaps 33. Instead of column 33 (FIG. 2), connection channels 31 in the form of bores are provided in the embodiment according to FIG. 3, in which flow resistances 32 are arranged.

The gear hub 12 is connected via its gear teeth 13 in a rotationally fixed but axially displaceable manner to a synchronizer body 8 which is arranged in a rotationally fixed manner on the gear shaft 1. If a speed difference occurs between the shifting hub 12 and the driving ring 10, the planet gears 24 convey liquid via the gaps 33 or connecting channels 31 dimensioned as throttling resistances, optionally with additionally arranged flow resistances 32, and thus transmit a torque between the driving ring 10 and the shifting hub 12. until these parts are synchronized. This so-called synchronization torque depends on the viscosity of the liquid and the speed difference and thus the volume flow of the gear pump and the size of the throttle resistance. That the viscosity of the liquid changes with the operating temperature and the speed difference accordingly changed the switching sequence, it is desirable to change the flow resistance 32 depending on these parameters so that the synchronization torque takes a favorable course taking into account the switching function and the switching comfort. It is therefore advantageous that the flow resistances 32 are changed by means of parameter-controlled axial slides or rotary slides or a combination of both.

The clutch is switched by means of a shift fork, not shown, which engages in a groove 11 of the driving ring 10 and moves the sliding sleeve 9 axially in the direction of the gears 2 or 3. The shift fork can be adjusted by hand or by automatic actuators.

After a short shift travel, a single-toothing 20 on the driving ring 10 butt meets a driving toothing 17 on a driving 15, which is non-rotatably connected via a driving toothing 16 to a gearwheel 2, 3 and by a wave spring 18 which is supported with respect to the gearwheel 2, 3 , is pressed against a stop disk 19. If the engagement teeth 20 butt meet the driver teeth 17, the driver 15 can deflect axially elastically until the engagement teeth 20 engage in the tooth gaps of the driver teeth 17 due to a peripheral force of a driven gear element 1 or 2, 3. Due to the coupling between the driver 15 and the driver ring 10, a synchronous torque is built up in the slip clutch 14, which acts until synchronism between the gear 2 or 3 and the transmission shaft 1 is achieved. Locking devices, not shown, or a corresponding software at a automatic switching prevent that the sliding sleeve 9 can be switched on before approximately synchronism has been achieved.

In synchronism, the sliding sleeve 9 is shifted further and its switching teeth 13 meet a coupling toothing 6 of a coupling body 5, which is non-rotatably connected to the gearwheel 2 or 3 via driving teeth 7 and is axially elastically flexible via a wave spring 21 on the gearwheel 2 or 3 supports. If the gear teeth 13 meet tooth gaps in the dome teeth 6, they engage in the dome teeth 6 and the shift is complete. The switching position is expediently secured by conventional locking means, for. B. undercuts, resilient locking elements or the like. If the gear teeth 13 meet bluntly on the coupling teeth 6, the coupling body 5 deviates axially until a circumferential force rotates the gear teeth 13 with respect to the coupling teeth 6 by a corresponding angular range and engages the gear teeth 13 in the coupling teeth 6.

Since the circumferential forces which cause the engagement of the engagement teeth 20 and the shift teeth 13 do not generate any axial reaction forces, the shift force over the course of the shift is determined only by the low resistances of the latching means and the wave springs 18 and 21. This results in low, largely uniform switching forces over the entire switching range. Reference numerals

1 gear shaft 30 pressure side

2 gear 31 connecting channel

3 gear 32 flow resistance

4 bearings 33 gap

5 coupling bodies

6 coupling teeth

7 drive teeth

8 synchronizer bodies

9 sliding sleeve

10 drive ring

11 groove

12 shift hub

13 gear teeth

14 slip clutch

15 drivers

16 drive teeth

17 drive teeth

18 corrugated spring

19 stop disc

20 single toothing

21 corrugated spring

22 ring gear 3 planet carrier 4 planet gear

25 Bore 6 recess 7 cover 8 seal 9 suction side

Claims

Patent claims

1. Positive clutch with a sleeve carrier (8), which is rotatably connected to a component to be coupled (1), with a sliding sleeve (9), which is constructed from a drive ring (10) and a shift hub (12), which via a Slipping clutch (14) are connected to one another, the driver ring (10) cooperating with a driver (15) which is connected in a rotationally fixed manner to a second component (2, 3) to be coupled, and the shifting hub (12) in a rotationally fixed but axially displaceable manner the sleeve carrier (8) is connected and cooperates with a coupling body (5) which is non-rotatably attached to the second component (2, 3) to be coupled, characterized in that the slip clutch (14) is a fluid coupling in which the torque is above a viscous agent is transferred.

2. Clutch according to claim 1, characterized in that the slip clutch (14) is a volumetric pump.

3. Clutch according to claim 1, characterized g e k e n n z e i c h n e t that the slip clutch (14) is a centrifugal pump.

4. Clutch according to claim 1, characterized in that the slip clutch (14) is a viscous clutch.

5. Clutch according to claim 2 or 3, characterized in that the slip clutch (14) conveys liquid via a flow resistance (32).

6. Clutch according to claim 5, characterized in that the flow resistance (32) is a variable throttle point.

7. Clutch according to claim 6, characterized in that the flow resistance (32) is controlled or regulated depending on the speed of a component, a speed difference or an nth derivative of the speed according to time.

8. Clutch according to claim 7, characterized g e k e n n z e i c h n e t that the flow resistance (32) is a centrifugal valve.

9. Clutch according to claim 6, characterized in that the flow resistance (32) is controlled or regulated as a function of a component, operating medium or ambient temperature or a temperature gradient.

10. Clutch according to claim 5, characterized in that the flow resistance (32) is controlled or regulated as a function of a predetermined period of time or over a time course.

11. Clutch according to one of claims 5 to 10, characterized in that the slip clutch (14) is an internal gear pump.

12. Clutch according to claim 11, characterized in that the slip clutch (14) has a plurality of planet gears (24) mounted in a planet carrier (23) which mesh with a ring gear 22 attached to the driving ring (10) and are filled with liquid in one Space.

13. Clutch according to claim 12, characterized in that a suction side (29) of a planet gear (24) is connected via a connecting channel (31) to a pressure side (30) of another planet gear (24).

14. Clutch according to claim 13, characterized in that the flow resistance (32) is arranged in the connecting channel (31).

15. Clutch according to claim 14, characterized in that the flow resistance (32) is formed by a rotary slide valve or axial slide valve.