Differential device

Abstract

Provided is a differential device that outputs torque around a shaft, and that is provided with: a housing that is provided with a first wall that extends in the radial direction at a first end with respect to the shaft, a second wall that extends in the radial direction at a second end with respect to the shaft, and a peripheral wall that connects the first wall and the second wall; a chamber is defined by the first wall, the second wall and the peripheral wall; and a differential gear set housed in the chamber and including a first side gear facing the first wall, a second side gear facing the second wall, a plurality of pinion shafts extending in the radial direction, and a plurality of pinions rotatably supported by the pinion shafts and meshing with the first side gear and the second side gear, a differential distribution unit that differentially distributes the torque received by the pinion shaft to the first side gear and the second side gear; a friction clutch that is disposed between the first side gear and the first wall and brakes the first side gear with respect to the first wall; a cam mechanism disposed coaxially with the shaft outside the housing and adjacent to the second wall, the cam mechanism converting a rotational force around the shaft into a thrust force in the direction of the shaft; and a transmission member that is in contact with the friction clutch and applies the thrust force, the transmission member including a plurality of plungers capable of transmitting the thrust force, the plungers extending parallel to the shafts and passing between the plurality of pinions or between the plurality of pinion shafts, and the transmission member being in contact with the friction clutch.

Description

Technical Field

[0001] The present invention relates to an electronically controlled limited slip differential (LSD) device suitable for differentially outputting torque to axles of equal length. Background Art

[0002] In a car, the left and right axles do not necessarily rotate at the same speed, so it is necessary to allow a difference between them. In order to transmit torque to the two axles while allowing the difference, a differential device is used.

[0003] When either of the left or right drive wheels loses traction, the differential device will idle and will not be able to transmit torque to the other drive wheel. In order to avoid this situation, some differential devices have a mechanism for limiting the differential. One example is an electronically controlled limited slip differential (LSD) that utilizes a multi-plate clutch. If the pressure applied to the multi-plate clutch is increased or decreased under electronic control, the degree of differential limitation changes accordingly. If sufficient pressure is further applied, the multi-plate clutch will not slip, so the so-called differential lock can also be achieved. Patent document 1 discloses related technology.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent document 1: International patent application publication WO2019 / 111294A1 Summary of the invention

[0007] The multi-plate clutch needs to be adjacent to the side gear, and the actuator that applies pressure to the multi-plate clutch needs to be arranged adjacent to the multi-plate clutch. The multi-plate clutch and the actuator must be arranged to the side of the differential device. Therefore, the two axles cannot be made equal in length, or if the two axles are made equal in length, the differential device has to be arranged to one side of the left or right in the vehicle. Such an arrangement may cause a difference in characteristics between the two axles and then between the two wheels. The differential device disclosed below provides a solution to this problem.

[0008] According to one embodiment, a differential device for outputting torque around an axis comprises: a housing, which comprises a first wall extending radially at a first end of the axis, a second wall extending radially at a second end of the axis, and a peripheral wall connecting the first wall and the second wall, wherein the first wall, the second wall, and the peripheral wall divide a chamber; a differential gear set, which is accommodated in the chamber and comprises a first side gear facing the first wall, a second side gear facing the second wall, a plurality of pinion shafts extending radially, and a plurality of pinion gears respectively rotatably supported on the pinion shafts and meshing with the first side gear and the second side gear, wherein the pinion gears are connected to the first side gear and the second side gear, and the pinion gears are connected to the first side gear and the second side gear. The above-mentioned torque received by the wheel axle is differentially distributed to the above-mentioned first side gear and the above-mentioned second side gear; a friction clutch is arranged between the above-mentioned first side gear and the above-mentioned first wall, and brakes the above-mentioned first side gear relative to the above-mentioned first wall; a cam mechanism is arranged coaxially with the above-mentioned shaft outside the above-mentioned housing and adjacent to the above-mentioned second wall, and converts the rotational force around the above-mentioned shaft into a thrust in the direction of the above-mentioned shaft; and a transmission component, which includes a plurality of plungers, and is connected to the above-mentioned friction clutch and applies the above-mentioned thrust, wherein the above-mentioned plungers pass through the above-mentioned plurality of pinion gears or between the above-mentioned plurality of pinion gear shafts and extend parallel to the above-mentioned shaft, and are capable of transmitting the above-mentioned thrust. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is an elevation view of a differential device according to one embodiment.

[0010] Figure 2 It is a side view of the differential device.

[0011] Figure 3 This is a cross-sectional side view of the differential device, taken from Figure 1 The diagram is taken along line III-III.

[0012] Figure 4 This is a cross-sectional view of the differential device, from Figure 2 The diagram is taken along line IV-IV.

[0013] Figure 5 is a cross-sectional partial elevational view of a differential device, particularly showing its actuator and its surroundings.

[0014] Figure 6 It is an elevation view of a differential device according to another embodiment.

[0015] Figure 7 is a cross-sectional view of a differential device according to another embodiment, and is similar to Figure 4 The corresponding figure.

[0016] Figure 8 is a cross-sectional view of a differential device according to yet another embodiment, Figure 4 , Figure 7 The corresponding figure.

[0017] Fig. 9 is a cross-sectional partial elevational view of a differential device, particularly showing its actuator and its surroundings.

[0018] Fig.10 It is schematically indicated Fig. 9 A perspective view of the cam mechanism in the actuator is shown. DETAILED DESCRIPTION

[0019] Hereinafter, several exemplary embodiments will be described with reference to the accompanying drawings. In the following description and in the scope of the invention to be protected, unless otherwise specified, the shaft refers to the rotating shaft of the differential device. The rotating shaft is usually consistent with the rotating shaft of the axle or cam mechanism, but consistency is not required. In addition, for ease of description, sometimes right and left are distinguished, and of course, the embodiment in which the left and right are reversed is also possible. It should be particularly noted that the drawings may not be shown with an accurate scale, so the mutual dimensional relationship is not limited to the relationship shown in the figure.

[0020] An example of a bevel gear type differential device is described below, but it is of course possible to use other types such as a face gear type.

[0021] For example, refer to Figures 1 to 4 , the differential device can be used to distribute the torque around the axis X to the left and right axles differentially. The differential device generally comprises: a housing 1, which can rotate around the axis X; a differential gear set 3, which is accommodated in the housing 1; a friction clutch 5, which is used to limit the differential of the differential gear set 3; a cam mechanism 7, which is arranged on the side opposite to the friction clutch 5 and is used to drive it; and a transmission component 9, which transmits thrust from the cam mechanism 7 to the friction clutch 5. In the example shown in the figure, the motor 61 connected to the planetary carrier is connected to the cam mechanism 7 from the outside via the reduction gear set 63, thereby causing it to operate, thereby applying thrust to the friction clutch 5. However, as Figures 6 to 8 As in the examples shown, the motor 61 can also be arranged coaxially with the differential device.

[0022] Mainly return and refer to Figure 1 The housing 1 is composed of a first wall 11 extending radially and substantially perpendicular to the axis X at its left end, a second wall 13 at the right end opposite to the first wall 11, and a peripheral wall 15 connecting the walls 11 and 13. These walls 11, 13, and 15 define a chamber, and the chamber accommodates the gear set 3 and the friction clutch 5. The boss 21 protrudes axially from the first wall 11, and the boss 23 protrudes axially from the second wall 13, and is respectively supported by the bearings of the planetary carrier, so that the housing 1 as a whole can rotate around the axis X. In order to receive torque from the engine or the drive motor, the housing 1 can be combined with the ring gear, but in Figure 1 Not depicted.

[0023] The differential gear set 3 is a mechanism for differentially distributing the torque about the axis X to the left and right axles. Figure 3 , Figure 4 The differential gear set 3 includes, for example, one or more pinion shafts 35 , pinion gears 37 rotatably supported on the pinion shafts 35 , and first side gears 31 and second side gears 33 respectively meshing with the pinion gears 37 .

[0024] The pinion shafts 35 may be short round bars extending in the radial direction, or may be combined in a cross shape as shown in the figure. The outer ends of the pinion shafts 35 are connected to the peripheral wall 15, thereby receiving torque from the housing 1. For example, the connection may be as follows: Figure 1 As shown in FIG. 1 , a so-called C-shaped ring is used, or other fixing means such as a pin can be used. Alternatively, instead of this structure, Figure 8 As shown in the example, the inner ends of the pinion shafts 35 are connected to each other through a so-called cross shaft via an annular member. In addition, the outer ends of the pinion shafts 35 may not be connected to the peripheral wall 15, but may be connected to other elements (in Figure 8 In the example, a cage-shaped transmission component 9) is engaged and receives torque via it.

[0025] Reference Figure 4 , Figure 7 , Figure 8 In any one of the above, the first side gear 31 faces the first wall 11, and the second side gear 33 faces the second wall 13, and they are respectively connected to the axle. For connection, each side gear 31, 33 has a spline or the like on its inner circumference. The side gears 31, 33 are meshed with the pinion gear 37 so as to be rotatable around the pinion shaft 35, so that both receive torque and can be differential with each other. Therefore, the differential gear set 3 differentially distributes the received torque to the side gears 31, 33.

[0026] The friction clutch 5 is arranged between the first side gear 31 and the first wall 11, and receives thrust to exert braking force. In the illustrated example, it is a multi-plate clutch, but it can also be other forms of friction clutches. In the case where the friction clutch 5 is a multi-plate clutch, it is composed of outer plates and inner plates that are respectively roughly disc-shaped and alternately stacked. In order to engage, the outer plate can have a wing protruding radially outward, and the inner plate can have a flange protruding inward. Correspondingly, the housing 1 can have a wing groove, and the first side gear 31 can have a flange groove. When the alternately stacked plates are subjected to thrust in the axial direction via the transmission component 9, the first side gear 31 is braked relative to the first wall 11 by the mutual friction force, thereby limiting the differential of the differential gear set 3 according to the thrust.

[0027] The cam mechanism 7 has a structure for converting the rotational force of the motor 61 into an axial thrust. Figure 4 Combination Figure 5 , a combination of a drive plate 71, a thrust plate 73 opposed thereto, and a cam structure interposed therebetween. The cam structure is composed of, for example, an inclined surface provided on one or both of the plates 71 and 73, and a cam ball 75 capable of rolling on the inclined surface. A roller may be used instead of the cam ball, or the cam ball may be omitted, and the inclined surface on one side and the protrusion on the other side may be made to slide directly and press each other.

[0028] The drive plate 71 can rotate around the axis X, but is fixed in the axial direction. In order to rotatably support the drive plate 71, a bearing 77 may be sandwiched between the second boss 23 and the drive plate 71. Figure 2 As shown, the drive plate 71 has gear teeth for meshing with the reduction gear set 63 at least partially around the drive plate 71, and is driven by the motor 61 via the reduction gear set 63 to rotate around the axis X. On the other hand, the thrust plate 73 is stopped from rotating around the axis X, but is movable in the axial direction. In order to stop the rotation, for example, the planetary carrier or other fixed components can be provided with a snap-fit ​​portion 41. The snap-fit ​​portion 41 is engaged with the thrust plate 73 to stop the rotation.

[0029] like Figure 4 , Figure 5 As best shown, the cam mechanism 7 is arranged outside the housing 1 and adjacent to the second wall 13, and in particular, the thrust plate 73 is opposite to the transmission component 9 and can directly apply thrust thereto. The transmission component 9 can be formed into a flat annular shape corresponding thereto at least in the portion opposite to the thrust plate 73. The transmission component 9 rotates together with the housing 1, and therefore, preferably, a thrust bearing 79 is interposed between the thrust plate 73 and the transmission component 9. Alternatively, there may be no thrust bearing and direct or indirect contact and sliding. When the drive plate 71 is rotated by the motor 61, the thrust plate 73 is driven in the axial direction by the clamped cam structure, whereby thrust acts on the transmission component 9.

[0030] See for example Figure 1 , Figure 3 , Figure 4 In order to transmit the thrust to the friction clutch 5, the transmission component 9 is also integrally or separately provided with a plurality of plungers 91 extending from the right end to the left end of the housing 1 in parallel with the axis X. An opening 17 is provided in the second wall 13 in a manner of penetrating the plunger 91, and the plunger 91 faces the cam mechanism 7 through the opening 17. The housing 1 may also be provided with a groove or a cavity 19, for example, on the inner surface of the peripheral wall 15 in correspondence with the plunger 91, and the plunger 91 is respectively guided by the groove or the cavity 19 to maintain parallelism with respect to the axis X.

[0031] As through e.g. Figure 3 It can be understood that the plungers 91 extend from the second wall 13 side to the first wall 11 side through the pinions 37. Preferably, the plurality of plungers 91 are symmetrically arranged around the axis X. This is conducive to uniformly transmitting the thrust around the axis.

[0032] The transmission member 9 may further include a pressing member 93 integrally or separately connected to the plunger 91 at one end of the friction clutch 5 side. The pressing member 93 can be in surface contact with the friction clutch 5, thereby allowing thrust to act on the friction clutch 5 symmetrically about the axis.

[0033] Or, if Figure 8 As shown, the transmission member 9 as a whole may be in a cage-like form surrounding the differential gear set 3. In this case, on the side facing the friction clutch 5, the transmission member 9 is in a deep bowl-like form that accommodates the first side gear 31, and a plurality of plungers 91 may be branched and extended from the edge thereof. Each plunger 91 may also extend toward the second wall 13 by passing between the pinion shafts 35. Of course, the plurality of plungers 91 may also be arranged symmetrically around the axis X.

[0034] In this case, the inner surface of the peripheral wall 15 has a groove 19 engaged with the transmission member 9, and the plurality of plungers 91 abut against the side surface of the pinion shaft 35, so that the transmission member 9 can also be responsible for the torque transmission from the housing 1 to the pinion shaft 35. In this case, the transmission member 9 is responsible for transmitting the thrust from the cam mechanism 7 to the friction clutch 5, as in the example described above.

[0035] As mentioned above, Figures 6 to 8 As shown in the examples, the motor 61 can be arranged coaxially with the differential device. In this case, the motor 61 and the cam mechanism 7 can also constitute an integrated actuator. For example, the whole is accommodated in the housing 83 and integrated, and supported on the boss 23. The actuator as a whole can rotate relative to the boss 23, but is stopped relative to the planetary carrier. In addition, it is fixed in the axial direction relative to the boss 23 or the planetary carrier by a C-ring or the like, thereby bearing the reaction force of the thrust exerted by it.

[0036] like Fig. 9 As best shown in FIG. 1 , the motor 61 is composed of a rotor 65 and a stator 67 opposed to the rotor 65 with a gap G therebetween, roughly similar to the prior art. It may also be a so-called radial gap motor that maintains a gap G in the radial direction, but the illustrated example is an axial gap motor that maintains a gap G in the axial direction. The rotor 65 and the stator 67 can both be arranged coaxially with the axis X, but the stator 67 is stopped by, for example, the housing 83, and the rotor 65 can rotate relative to them. In order to support the rotor 65 rotatably, a bearing such as a ball bearing 85 can be used, which can be interposed between the rotor 65 and the stator 67, for example. A plurality of coils arranged in the circumferential direction generate magnetic flux according to the input power, and the magnetic flux jumping over the gap G drives the rotor 65 to rotate around the axis X. In addition, the rotor 65 is coupled to the cam mechanism 7 to drive it.

[0037] The cam mechanism 7 can also be as described above. Figure 5 As shown in the example, there is a drive plate 71, a thrust plate 73 and a cam ball 75 between them. Fig. 9 , Fig.10 As shown in the example, a mechanism using a planetary gear may also be used. According to this example, the drive plate 71 and the thrust plate 73 are internal gears having internal teeth 71t and 73t, respectively, and are connected to the drive plate 71 and the thrust plate 73. Figure 5 The examples shown are different, but all can rotate around the axis X. A plurality of planetary gears 81 are meshed on their inner circumferences. Usually, the planetary gears 81 are arranged symmetrically about the axis X. A sun gear portion 67t having external teeth and being stopped is arranged on the radially inner side of the planetary gears 81, and the sun gear portion 67t meshes with these planetary gears 81. In the example shown in the figure, the sun gear portion 67t is integrally extended from the stator 67, but this is not necessary, and for example, it can also be fixed to the housing 83.

[0038] Here, the number of teeth of the internal teeth 71t of the drive plate 71 and the number of teeth of the internal teeth 73t of the thrust plate 73 are slightly different, so when the drive plate 71 is rotated by the motor 61, a rotation difference is generated between the drive plate 71 and the thrust plate 73. Using this rotation difference, the cam ball 75 pushes up the thrust plate 73, thereby converting the rotational force into thrust. Of course, as described above, it is also possible to use an appropriate cam structure without the cam ball.

[0039] The degree of the cam mechanism 7 is usually greater than that of the reduction gear, and can be appropriately adjusted by the difference in the number of teeth. That is, the actuator of this embodiment can controllably exert a particularly large thrust compared to the prior art. Figure 5 In the present embodiment, the thrust plate 73 is also adjacent to the transmission member 9, and the friction clutch 5 can be operated via the thrust plate 73. The actuator of the present embodiment can also be used for other purposes.

[0040] According to any embodiment, in the differential device, the friction clutch near the left end and the cam mechanism near the right end are of approximately the same size, and the differential device has an approximately bilaterally symmetrical structure. Therefore, the left and right axles can be made equal in length, as in a differential device without a differential limiting device. In addition, the differential device of this embodiment is not particularly large compared to a differential device without a differential limiting device, so it can be used interchangeably with the differential device.

[0041] Several embodiments have been described, and corrections or modifications of the embodiments can be made based on the above disclosure.

Claims

1. A differential device that outputs torque about an axis, the differential device comprising: a housing having a first wall extending radially at a first end with respect to the shaft, a second wall extending radially at a second end with respect to the shaft, and a peripheral wall connecting the first wall and the second wall, wherein the first wall, the second wall, and the peripheral wall define a chamber; a differential gear set housed in the chamber, comprising a first side gear facing the first wall, a second side gear facing the second wall, a plurality of pinion shafts extending in the radial direction, and a plurality of pinion gears rotatably supported on the pinion shafts and meshing with the first side gear and the second side gear, and differentially distributing the torque received by the pinion shafts to the first side gear and the second side gear; a friction clutch disposed between the first side gear and the first wall to brake the first side gear relative to the first wall; a cam mechanism, which is arranged coaxially with the shaft outside the housing and adjacent to the second wall, and converts a rotational force around the shaft into a thrust force in the direction of the shaft; as well as A transmission component includes a plurality of plungers, and is connected to the friction clutch and applies the thrust, wherein the plungers pass through between the plurality of pinion gears or between the plurality of pinion gear shafts and extend parallel to the shaft, and are capable of transmitting the thrust.

2. The differential device according to claim 1, characterized in that: The second wall further includes an opening that passes through the second wall, and the opening is set to a size that allows the plunger to pass therethrough and face the cam mechanism.

3. The differential device according to claim 1, characterized in that: The peripheral wall includes a groove or a cavity for guiding the plunger in order to hold the plunger parallel to the axis.

4. The differential device according to claim 1, characterized in that: The transmission member includes a pressing member which is integral with or separate from the plurality of plungers and is continuous in the circumferential direction and is in surface contact with the friction clutch, so that the thrust acts on the friction clutch symmetrically with respect to the axis.

5. The differential device according to claim 1, characterized in that: The clutch includes an inner plate engaged with the first side gear and an outer plate engaged with the housing, and the inner plate and the outer plate are stacked on each other in the axial direction to form a multi-plate clutch.

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