GB2494610A - Clamping clutch having first and second spring plates pivotable around a hinge joint to clamp a clutch plate - Google Patents

Abstract

A friction clutch, for a vehicle, comprises a first clamping spring plate 11 and a second clamping spring plate 13, wherein at least one of the clamping spring plates 11, 13 comprises teeth 15, 16 for transmitting a torque flow. The friction clutch also comprises a clutch plate 12 and a hinge-joint 14, wherein the first and second clamping spring plates 11, 13 enclose the clutch plate 12 and wherein the first and second clamping spring plates 11, 13 are pivotable around the hinge joint 14. The spring plates 11 & 13 preferably have a contact portion 23, preferably a bulge having a circular cross section, and a lever portion 20, 22. These friction clutches may be used in planetary gearboxes (fig 7).

Description

Description

Clamping Clutch A clutch is a mechanical device which provides for the transmission of power -and therefore usually motion -from one component, the driving member, to another, the driven member. A special form of a clutch is the brake.

Clutches are used whenever the ability to limit the transmission of power or motion needs to be controlled either in amount or over, for example electric screwdrivers limit how much torque is transmitted through use of a clutch and clutches control whether automobiles transmit engine power to the wheels.

In the simplest application, clutches are employed in devices which have two rotating shafts. In these devices one shaft is typically attached to a motor or other power unit (the driving member) while the other shaft (the driven member) provides output power for work to be done. In a drill for instance, one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two shafts so that they may be locked together and spin at the same speed (engaged), locked together but spinning at different speeds (slipping), or unlocked and spinning at different speeds (disengaged).

In the automotive sector, single plate and multiplate clutches are frequently used types of clutches, Often, the I-' single plate clutches are designed as dry clutches and the multiplate clutches as wet clutches. A wet clutch is immersed in a cooling lubricating fluid which also keeps the surfaces clean and gives smoother performance and longer life. Wet S clutches, however, tend to lose some energy to the liquid.

Since the surfaces of a wet clutch can be slippery (as with a motorcycle clutch bathed in engine oil), stacking multiple clutch disks can compensate for the lower friction and so eliminate slippage under power when fully engaged.

It is an object of the application to provide an improved friction clutch for the use in a powertrain of a motorized vehicle, especially for use in a planetary gearbox.

The friction clutch, which is also referred to as clamping clutch, comprises a first clamping spring plate and a second clamping spring plate. At least one of the clamping spring plates comprises teeth for transmitting a torque flow. The teeth are, for example, provided as outer teeth on a circular diameter of the clamping spring plate and they engage into spliries of a transmission part such as a shaft, a hollow shaft or a part of a casing. The torque flow may be directed from the splines to the teeth or also vice versa. The splines allow the transmission of the torque as well as a movement along an axis of a shaft.

Furthermore, the friction clutch comprises a clutch plate and a hinge-joint. The first clamping spring plate and the second clamping spring plate enclose the clutch plate and the first clamping spring plate and the second clamping spring plate are pivotable around the hinge joint. The clamping spring plates enclose the clutch plate at least partially such that contact regions of the clamping spring plates provide a fric- tional engagement to the clutch plate when the contact re-gions are moved towards the clutch plate.

A portion of the clamping spring plate serves as friction surface for frictional engagement and another portion of the clamping spring plate serves as a lever and as a return spring. Thereby, the required space and the number of re-quired parts is decreased. Furthermore, the contact pressure is increased through the lever effect.

Specifically, the first clamping spring plate and the second clamping spring plate may each comprise a contact portion for frictional contact with a contact portion of the clutch plate and a lever portion for actuation by a clutch actuation mechanism.

The contact portion of the clutch plate can be provided by a bulge, especially an outer bulge, and the contact portions of the first spring plate and second spring plate can be pro-vided by a rim, especially an outer rim, respectively. The forms of the rims match the Latin of the bulge to provide frictional contact between the rims and the bulge when the clutch is engaged. Specifically, the rims and the bulge may be rotationally symmetric to allow rotational movement of the rims relative to the bulge. The bulge of the clutch plate may be provided with a circular cross section. The circular cross section provides a smooth contact area.

The lever portions of the first spring plate and the second spring plate may be designed to have a straight cross section and the lever portions can be provided at an angle relative to the clutch plate wherein this angle is greater for an open clutch state than for a closed clutch state.

Especially, the hinge-joint may be provided by a retainer part which holds the first clamping spring plate and the sec-ond clamping spring plate together. Thereby, the hinge can be realized by simply assembling the first clamping spring part, S the retainer and the second clamping spring part. The hinge can be de-assembled by removing the retainer. If the retainer is provided by an elastic part, assembly and de-assembly can be achieved by bending the retainer outwards or inwards. Spe-cifically, the retainer part can be provided by a retainer ID ring.

In a further refinement, the first clamping spring plate coin- prises outer teeth and the second clamping spring plate com-prises outer teeth. Thereby, both clamping spring plate can engage in splines. which provides a stable movement. In a re-versed arrangement, the teeth of the clamping spring plates may also be designed as inner teeth.

The outer teeth of the first clamping spring plate and of the second clamping spring plate may be provided on brackets, es-pecially on brackets which are oriented at approximately 90° to a plane of the outer bulge. Thereby, space is provided for the hinge to move.

The brackets of the first clamping spring plate and the brackets of the second clamping spring plate can be provided at alternating positions and the retainer ring can be pro- vided in the brackets. The brackets and/or teeth at the al- ternating positions take up lateral forces in alternating di-rections. Thereby, a firm connection is achieved which can be easily assembled and de-assembled.

The application furthermore provides a clutch arrangement which comprises the abovementioned friction clutch. The clutch arrangement comprises an outer hollow shaft, an inner hollow shaft and an actuator. The actuator may be hydraulic or also electromechanic. An end of the actuator is in contact with an end of the lever portion of the first clamping spring plate.

The outer teeth of the first clamping spring plate and of the second clamping spring plate engage into spline teeth of the outer hollow shaft and inner teeth of the clutch plate engage with spline teeth of the inner hollow shaft.

Specifically, the actuator can be provided by a piston which is connected to a hydraulic channel of a hydraulic actuation mechanism.

Furthermore, the application discloses a planetary gearbox which comprises the abovementioned friction clutch. The fric-tion clutch is connected to at least one of a sun gear, a planetary carrier or a ring gear of a planetary gear set of the planetary gearbox. Specifically, the friction clutch may be connected via the inner teeth of the clutch plate or via the outer teeth of one of the clutch spring plates which ena-gage into a part that moves together with the sun gear, the planetary carrier or the ring gear of the planetary gear set.

The planetary gear box may comprise further planetary gear sets and friction clutches.

Moreover, the application discloses a powertrain with the abovementioned planetary gearbox, wherein an output shaft of 3D a motor is connected to an input shaft of the planetary gear- box, wherein an output shaft of the planetary gearbox is con-nected to an input part of the powertrairt, for example to a gearwheel, a chain, a shaft and/or a differential. Specifi-cally, the motor may be provided by a combustion engine and the planetary gearbox may be designed as a gearbox of an automatic transmission Other engines such as electric motors are also possible.

The application discloses furthermore a motorized vehicle with the abovementioned powertrain, wherein the powertraifl is connected to wheels of the motorized vehicle and to a motor of the motorized vehicle, for example via a crankshaft of the motor. A motorized vehicle in this sense comprises especially passenger cars and buses but also motorbikes, utility vehi-cles and lorries.

The application is now explained in further detail with reN erence to the following figures in which Figure 1 illustrates an exploded view of a clamping clutch according to the application, Figure 2 illustrates an assembled view of the clamping clutch, Figure 3 illustrates a cross section through a section of a transmission with the clamping clutch in an open state, Figure 4 shows an enlarged portion of Fig. 3 with the clamp-ing clutch in a closed state, Figure 5 shows the enlarged portion of Fig. 4 with an mdi-cation of a lever effect, Figure 6 shows an enlarged portion of Fig. 3, and Figure 7 shows a powertrain with a planetary gearbox that comprises clamping clutches.

In the following description, details are provided to de-scribe the embodiments of the application (invention). It shall be apparent to one skilled in the art, however, that the embodiments may be practised without such details.

Fig. 1 shows an exploded view of a clamping clutch 10 accord-ing to the application. The clamping clutch comprises a first clamping spring plate 11, a clutch plate 12, a second clamp- ing spring plate 13 and a retainer ring 14. The first clamp- ing spring plate U comprises outer teeth 15 which are pro-vided on the periphery of the first clamping spring plate 11 at regular distances. In the same way, the second clamping spring plate 13 comprises outer teeth 16 which are provided on the periphery of the second clamping spring plate 13 at regular distances.

The clutch plate 12 comprises an outer bulge 23 and a ring shaped surface 24. The ring shaped surface 24 of the clutch plate 12 comprises indentations 25, which are provided at regular intervals along an inner diameter of the ring shaped surface 24. The indentations 25 toxin inner teeth 26, which are located between the indentations 25. The inner teeth 26 are provided to enable a movement on a splined shaft, which is not shown in Fig. 1.

The outer teeth 15 and the outer teeth 16 of the clamping spring plates 13. and 13 are provided on brackets 17 and brackets 18, respectively, which protrude from a rotationally symmetric main body of the first clamping spring plate 11 and of the second clamping spring plate 13. respectively. The main body of the first clamping spring plate 11 comprises an outer rim 19 and a lever portion 20, which is shaped like a Belleville washer. Likewise, the main body of the second clamping spring 13 comprises an outer rim 21 and a lever por-tion 22, which is shaped like a Belleville washer.

The cross section of the main body of the clamping spring plates 11, 13 comprises a straight section, which corresponds to the respective lever portion 20, 22 and a round portion, which corresponds to the respective outer rim 19, 21. This can be best seen in Fig. 4. The outer rims 19, 21 have a shape of a circular groove with a round cross section. The outer rims 19, 21 of the clamping spring plates 11, 13 are formed to match the shape of the outer bulge 23 of the clutch plate 12. The clamping spring plates ii. and 13 of Fig. 1 have identical shapes. Thereby, the production and assembly is fa cilitated. However, embodiments in which the clamping spring plates have different shapes are also possible.

The retainer ring 14 is an open ring with a gap 27. The di-ameter and the elasticity of the retainer ring 14 are such that the retainer ring 14 can be lifted above the outer teeth 15, 16. The diameter of the retainer ring 14 is made such that the retainer ring 14 fits into the angles 17, 18 in an assembled state of the clamping clutch 10. This can be seen in Fig 2.

Fig. 2 shows an assembled state of the clamping clutch 10. In the assembled state, the outer teeth 15 of the first clamping spring plate 11 are on a side of the second clamping spring plate 12 while the outer teeth 16 of the second clamping spring plate 13 are on a side of the first clamping spring plate 11. This can also be seen in the cross sections of Fig. 3 and 4. In the assembled state, the retainer ring 14 is lo-cated between the brackets 17 and 18 on which the outer teeth and 16 are provided. Thereby, the first clamping spring plate 11 and the second clamping spring plate 13, which en-close the clutch plate 12. are held together firmly.

Figure 3 illustrates a cross section through a section of a transmission. Fig. 3 shows the clamping clutch 10 in an open state wherein the piston 34 is in contact with receiving parts 29 and wherein the outer rims 19, 21 are detached from the outer bulge 23. The transmission comprises an input shaft 30, the clamping clutch 10, an actuation mechanism 31 and an output shaft 32.

The actuation mechanism 31 comprises an inlet channel 33 for a fluid and a piston 34 which is in contact with an inner end of the lever portion 20 of the first clamping spring plate 11. An arrow 35 indicates a closing movement of the piston 34.

& outer hollow shaft 36 is formed out on the input shaft 30, and the outer hollow shaft 36 encloses the actuation mecha-nism 31 and the clamping clutch 10. The outer teeth 15 and the outer teeth 16 engage into spline teeth 8, also known as splines 8, which are provided on an inner surface of the outer hollow shaft 36. The splines 8 allow an axial movement of the clamping spring plates 11 and 13. In the view of Fig. 3. this can be seen for one outer tooth 15 of the first clamping spring plate 11.

A retaining plate 37 and a retainer 38 are provided on the inner surface of the outer hollow shaft 36. The retaining plate 37 is provided on the side of the output shaft 32 and is in contact with the lever portion 22 of the second clamp-ing spring plate 13. The retainer 38 is provided on the side of the output shaft 32 relative to the retaining plate 37 and is in contact with the retaining plate 37, An inner hollow shaft 39 is formed out on the output shaft 32. On an outer surface of the inner hollow shaft 39 splines 9 are provided in which the inner teeth 25 of the clutch plate 12 engage. The splines 9 allow an axial movement of the clutch plate 12 while coupling the rotational motion of the clutch plate to the rotation motion of the output shaft 32.

On the other hand, the rotational motion of the first clamp-ing spring plate 11 and of the second clamping spring plate 13 is coupled to the rotational motion of the input shaft 33 via the outer teeth 15, 16.

Furthermore, receiving parts 29 are provided an the inner hollow shaft 36 which have a shape that matches with the shape of the piston 34 such that a fluid volume between the piston 34 and the inner hollow shaft 36 in an open state of the clamping clutch 10 is minimized.

The retaining plate 37 exerts a reaction force on the second clamping spring plate 13 while the piston exerts an action force on the first clamping spring plate 11.

Fig. 5 shows the cross section of Fig. 3, wherein a lever ef-fect is indicated. The clamping spring plates 11, 13 act similar to pliers but with the difference that the clamping spring plates 11, 13 are elastic and that the clamping force is provided on the same side of a hinge axis than the outer rims 19, 21 of the clamp spring plates 11, 13 which clamp the clutch plate 12 in between them, The retainer ring 14 provides the hinge axis. Let the dis-tance between a contact point of a clamp spring plate 11, 13 1].

with the clutch plate 12 and the hinge axis be denoted by 1.2 and a distance between the inner end of a clamp spring plate 11, 13 and the hinge axIs be denoted by Li. Then, the quo-tient L1/L2 gives the force amplification at the contact point. Herein, the approximation is made, that the force to move the clamping clutch is small in comparison.

Figure 6 shows the enlarged portion of Fig. 4 with the clamp-ing clutch in a closed state.

The clamping clutch 10 is closed by pressing a fluid through the hydraulic channel 33. The pressure of the fluid moves the piston 34 away from the outer hollow shaft 36 and towards the retaining plate 37. An outer end of the piston 34 presses an inner edge of the lever portion 20 Qf the first clamping spring plate 11 towards the retaining plate 37. Due to the action force of the piston 34 the clamping clutch 10 moves towards the retaining plate 37. The outer rims 19, 21 are pressed against the outer bulge 23 of the clutch disk.

The motion of the clamping clutch is guided on the outer hol-low shaft 36 by the inner spline teeth 8 of the outer hollow shaft 36 in which the outer teeth 15, 16 of the first and second clamping spring plates 11, 13 engage. Furthermore, the motion of the clamping clutch 10 is guided on the inner hollow shaft by the outer spline teeth 9 of the inner hollow shaft 39 in which the inner teeth 26 of the clutch plate 12 engage. The first clamping spring plate 11 and the second clamping spring plate 13 are supported with their outer rims 19, 21 on the outer bulge 23 of the clutch plate 12, as can be seen in Fig. 6. Thereby, a tilting of the first and second clamping spring plate 11, 13 during the movement is pre-vented.

In order to release the clamping clutch again, the pressure at the hydraulic channel is reduced. The spring force of the first and second clamping spring plates 11 and 13 provides a restoring force. The restoring force moves the clamping clutch 10 end the piston 34 away from the retaining plate 37 and moves the outer rims 19, 21 of the clamping spring plates 11, 13 away from the outer bulge 23 of the clutch plate until a disengaged position is reached. The disengaged position in which the outer rims 19, 21 have little or no frictional con-tact with the outer bulge 23 is shown in rig. 6.

In the engaged state of the clamping clutch 10, a torque is transmitted from the input shaft 30 via the outer hollow shaft 16, the splines B on the outer hollow shaft, the outer teeth 15 of the first clamping spring plate 11 and the outer teeth 16 to the outer rim 19 of the first clamping spring plate 11 and to the outer rim 21 of the second clamping spring plate 13. Through the frictional engagement of the outer rims 19, 21 with the outer bulge 23 of the clutch plate 12, the torque is transmitted to the clutch plate 12 via the inner teeth 26 of the clutch plate 12 and the splines 9 of the inner hollow shaft 39 to the output shaft 32.

fl another arrangement, the output shaft 32 may be an input shaft and the input shaft 30 may be an output shaft. In an arrangement which provides a braking clutch, the outer teeth lS 16 may also engage into splines $ that are provided on the inside of a part of a stationary casing.

Fig. 7 shows a powertrain 40 with a planetary gearbox 41 that comprises clamping clutches according to the application. In Fig. 7, the actuation mechanisms are not shown. The actuation mechanisms can be realized in a similar way as in a hydrauli-cally actuated automatic transmission but they may also be realized as motor driven mechanical actuators. An input shaft 42 of the planetary gearbox 41 is connected to a torque con- verter 43, which is connected to a crankshaft 44 of a combus-tion motor that is not shown. An output shaft 45 of the S planetary gearbox 41 is connected to a differential 46 which is connected to a front axis 47 with front wheels 48.

The planetary gearbox 41 comprises planetary gearsets P1, P2 and P3. Clamping clutches 49 and 50 are provided to connect the first planetary gearset Pt to the second planetary gearset P2. Clamping clutches 51, 52 are provided to connect the third planetary gearset P3 and the second planetary gearset P2 to the input shaft 42. Furthermore, clamping clutch 53 is provided to connect the first planetary gearset P1 to the gearbox casing and clamping clutch 54 is provided to connect the second planetary gearset P2 and the third planetary gearset P3 to the gearbox casing. By engaging and disengaging the six clamping clutches 49, 50, 51, 52, 53, 54 according to predefined patterns, various transmission ratios are achieved.

By using clamping clutches instead of clutch packs in the planetary gearbox of Fig. 7, a space between the first plane-tary gearset P1 and the second planetary gearbox P2 can be reduced significantly.

For the clamping clutch, various configurations are possible: the clamping spring plates 11, 13 may be connected to an in-put shaft and the clutch plate 12 to an output shaft or the clutch plate 12 may be connected to an input shaft and the clamping spring plates ii, 13 to an output shaft. The clamp-ing spring plates 11, 13 may be provided on the outside, relative to a rotation axis, and the clutch plate 12 on the inside as shown in the preceding Figures.

Alternatively, the clutch plate 12 may be provided on the outside and the clamping spring plates 11, 13 on the inside.

In the latter case, the arrangement is reversed with respect to the radial distance. For example, the outer teeth of the clamping spring plates become inner teeth which engage into the splines 9 of the inner hollow shaft 39 and the inner teeth of the clutch plate become outer teeth which engage into the splines 8 of the outer hollow shaft 36. The clutch plate itself takes the form of a clutch ring with an inner bulge.

for a braking clutch, such as the braking clutches 53, 54 of fig. 7, it can be advantageous to provide the clamping spring plates on the stationary part. Thereby, an actuator such as a piston can be made stationary with respect to the clamping spring plates.

A use of a clamping clutch according to the invention reduces significantly the number of required parts. In addition, the weight, the cost of the clutch and the total clutch length is reduced. This length reduction is particularly large in corn-parison to a multi plate clutch.

The clamping clutch is especially useful as a clutch in a planetary gear of an automatic transmission but its use is not limited to this application.

Although the above description contains much specificity, these should not be construed as limiting the scope of the embodiments but merely providing illustration of the foresee-able embodiments. Especially the above stated advantages of the embodiments should not be construed as limiting the scope of the embodiments but merely to explain possible achieve-ments if the described embodiments are put into practise.

Thus, the scope of the embodiments should be determined by the claims and their equivalents, rather than by the examples given.

Reference numbers clamping clutch 11 first clamping spring plate 12 clutch plate 13 second clamping spring plate 14 retainer ring outer teeth 16 outer teeth 17 brackets 1A brackets 19 outer rim lever portion 21 outer rim 22 lever portion 23 outer bulge 24 ring shaped surface indentations 26 inner teeth 27 gap of retainer ring 29 receiving parts input shaft 31 actuation mechanism 32 output shaft 33 hydraulic channel 34 piston closing movement 36 outer hollow shaft 37 retaining plate 38 retainer 39 inner hollow shaft powertrain 43. planetary gearbox 42 input shaft 43 torque converter 44 crankshaft output shaft 46 differential 41 front axis 48 wheels 49 clamping clutch clamping clutch 51 clamping clutch 52 clamping clutch 53 clamping clutch 54 clamping clutch

Claims (1)

1. <claim-text>Claims 1. Friction clutch (10) for a motorized vehicle, the fric-tion clutch (10) comprising -a first clamping spring plate (11), -a second clamping spring plate (13), at least one of the clamping spring plates (11, 13) com-prising teeth (15, 16) for transmitting a torque flow, -a clutch plate (12), -a hinge-joint (14), wherein the first clamping spring plate (U) and the sec-ond clamping spring plate (13) enclose the clutch plate (12) and wherein the first clamping spring plate (11) and the second clamping spring plate (13) are pivotable around the hinge joint (14).</claim-text> <claim-text>2 Friction clutch (10) according to claim 1, wherein the first clamping spring plate (11) and the second clamping spring plate (13) comprise a contact portion (19, 21) for frictional contact with a contact portion (23) of the clutch plate (12) and a lever portion (20, 22) for actua-tion by a clutch actuation mechanism 133, 34).</claim-text> <claim-text>3. Friction clutch (10) according to claim 2, wherein the contact portion (23) of the clutch plate (12) is provided by a bulge (23) and the contact portions (19, 21) of the first spring plate (11) and second spring plate (13) are provided by a rim (19, 21), respectively, and wherein the forms of the rims (19, 21) match the form of the bulge (23) 4. Friction clutch (10) according to claim 3, wherein the bulge (23) of the clutch plate (12) has a circular cross section.5. Friction clutch (10) according to one of claim 2 to 4, wherein the lever portions (20, 22) are provided at an angle relative to the clutch plate (12), and wherein this angle is greater for an open clutch state than for a closed clutch state.6. Friction clutch (10) according to one of the preceding claims, wherein the hinge-joint (14) is provided by a re-tainer part (14) which holds the first clamping spring plate (11) and the second clamping spring plate (13) to-gether.7. Friction clutch (10) according to claim 6, wherein the retainer part (14) is provided by a retainer ring (14).8. Friction clutch (10) according to one of the preceding claims, wherein the first clamping spring plate (11) com-prises outer teeth (15) and the second clamping spring plate (13) comprises outer teeth (16).9. Friction clutch (10) according to claim B, wherein the outer teeth (15, 16) of the first clamping spring plate (11) and of the second clamping spring plate (13) are provided on brackets (17, 18).10. Friction clutch (10) according to claim 9, wherein the brackets (17) of the first clamping spring plate (11) and the brackets (18) of the second clamping spring plate (13) are provided at alternating positions and wherein a retainer ring (14) is provided in the brackets (17, 18) 11. Clutch arrangement comprising a friction clutch (10) ac-cording to one of the claims 8 to 10, -an outer hollow shaft (36), an inner hollow shaft (39), and an actuator (34), wherein an end of the actuator (34) is in contact with an tO end of the lever portion (20) of the first clamping spring plate (11), wherein the outer teeth (15) of the first clamping spring plate (11) and of the second clamp-ing spring plate (13) engage into spline teeth (8) of the outer hollow shaft (36) and wherein inner teeth (26) of the clutch plate (12) engage with spline teeth (9) of the inner hollow shaft (39) 12. Clutch arrangement according to claim 11, wherein the ac tuator (34) is provided by a piston (34) which is con nected to a hydraulic channel (33) of a hydraulic actua-tion mechanism (31).13. Planetary gearbox (41) comprising a friction clutch (10) according to one of the claims 1 to 10, wherein the Fric-tion clutch (10) is connected to at least one of a sun gear, a planetary carrier or a ring gear of a planetary gear set (Cl, G2, G3) of the planetary gearbox ($1) 14. Powertrain with a planetary gearbox (41) according to claim 13, wherein an output shaft of a motor is connected to an input shaft (42) of the planetary gearbox (41) and wherein an output shaft (45) of the planetary gearbox 2].(41) is connected to an input part (46) of the power-train.15. Motorized vehicle with a powertrain according to claim 14, wherein the powertrain is connected to wheels NB) of the motorized vehicle and to a motor of the motorized ve-hicle.</claim-text>