JP2023167462A - power transmission device - Google Patents

Abstract

To provide a power transmission device capable of reducing a weight deviation and a drive torque deviation.SOLUTION: A power transmission device comprises: a differential device that distributes driving torque to a first output shaft and a second output shaft; a first planetary gear device and a second planetary gear device that are each equipped with a first element, and a second element and a third element that rotate in conjunction with the first element; and a linking part that links the third element of the first planetary gear device and the third element of the second planetary gear device. The first output shaft is coupled to the first element of the first planetary gear device, and the second output shaft is coupled to the first element of the second planetary gear device. The second element of the first planetary gear device has a control motor attached thereto, and rotation of the second element of the second planetary gear device is regulated.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power transmission device that distributes torque between two output shafts.

Background Art As a power transmission device that distributes torque between two output shafts, the prior art disclosed in Patent Document 1 is known. The prior art includes a differential device that distributes drive torque to two output shafts, and three planetary gear devices arranged on one output shaft. One of the elements of the planetary gear set is coupled to one output shaft, and another element of the planetary gear set is connected to the differential. When the control motor attached to the planetary gearset is actuated, a torque is applied to the differential that causes the elements of the planetary gearset to rotate in the opposite direction, thereby actively distributing the drive torque between the two output shafts.

German Patent Invention No. 102014112602

In the prior art, three planetary gear units are arranged on one output shaft, so there is a problem that the weight is biased to one side with the differential gear as a boundary, and the drive torque is biased.

The present invention has been made to solve this problem, and an object of the present invention is to provide a power transmission device that can reduce left and right weight and drive torque imbalance.

In order to achieve this object, the power transmission device of the present invention includes a differential device that distributes drive torque to a first output shaft and a second output shaft, a first element, and a differential device that distributes drive torque to a first output shaft and a second output shaft. a first planetary gear set and a second planetary gear set respectively comprising a rotating second element and a third element; a third element of the first planetary gear set and a third element of the second planetary gear set; and a connecting portion that connects the elements. The first output shaft is coupled to a first element of a first planetary gear set and the second output shaft is coupled to a first element of a second planetary gear set. A control motor is attached to the second element of the first planetary gear set, and rotation of the second element of the second planetary gear set is restricted.

The differential device includes a first side gear that is coupled to the first output shaft and rotates about the center axis, a second side gear that is coupled to the second output shaft and rotates about the center axis, and a first side gear that is coupled to the second output shaft and rotates about the center axis. The pinion may be provided with a pinion that meshes with the side gear and the second side gear and revolves around the central axis, and a differential case that supports the rotation axis of the pinion and applies a driving torque.

According to a first aspect, a first planetary gear device includes a first element coupled to a first output shaft, a second element and a third element that rotate in conjunction with the first element; a second planetary gear device including a first element coupled to the second output shaft, a second element and a third element that rotate in conjunction with the first element, and The generated drive torque is distributed to the first output shaft and the second output shaft. The third elements are connected to each other by the connecting portion, and rotation of the second element of the second planetary gear device is restricted. When the control motor applies torque to the second element of the first planetary gear set, the torque can be actively distributed between the first output shaft and the second output shaft. Since the planetary gear device is arranged on each of the two output shafts, it is possible to reduce weight deviation and drive torque deviation.

According to a second aspect, in the first aspect, the second element of the second planetary gear train is fixed to the stationary body by friction. Since the second element rotates when the torque of the second output shaft becomes excessive, the risk of component damage can be reduced.

According to a third aspect, in the first or second aspect, the first element is a carrier supporting a planetary gear meshing with the sun gear. Since the rotational speed transmitted from the second element to which the control torque is applied to the first element can be slowed down, the torque can be applied to the first element with a relatively small control torque.

According to a fourth aspect, in the first or second aspect, the first planetary gear set and the second planetary gear set are arranged symmetrically with respect to the differential. Therefore, the symmetry regarding the differential device can be improved.

It is a skeleton diagram of a power transmission device in one embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a skeleton diagram of a power transmission device 10 in one embodiment. The power transmission device 10 is a device that adjusts torque distribution between two output shafts. In this embodiment, a power transmission device 10 disposed in an automobile will be described. The power transmission device 10 includes a differential device 13 that distributes applied torque to a first output shaft 11 and a second output shaft 12, and a first planetary gear device 20 disposed on the first output shaft 11. and a second planetary gear device 30 disposed on the second output shaft 12.

The differential device 13 includes a differential case 14 in which a first gear 15 is provided in an annular shape around a central axis O, a first side gear 16 and a second side gear 17 that rotate around the central axis O, and a first side gear 16 and a second side gear 17 that rotate around the central axis O. A pinion 18 that meshes with the first side gear 16 and the second side gear 17 is provided. The side gears 16, 17 and the pinion 18 are bevel gears, and the direction of power transmission is changed by meshing between the bevel gears. A rotation axis 19 of the pinion 18 is provided in the differential case 14, and the pinion 18 revolves around the central axis O. The number of pinions 18 is appropriately set to one or more depending on the maximum torque of a drive motor (not shown), the weight of the automobile, the intended use, and the like.

The first output shaft 11 is coupled to the first side gear 16 on the center axis O, and the second output shaft 12 is coupled to the second side gear 17 on the center axis O. The first output shaft 11 and the second output shaft 12 extend in opposite directions. As long as the first output shaft 11 and the second output shaft 12 are connected on the central axis O, they do not need to be coaxial over the entire length of the shaft. The first output shaft 11 and the second output shaft 12 may be at an angle with respect to the central axis O. Wheels (not shown) are attached to the first output shaft 11 and the second output shaft 12, respectively.

Torque (driving torque) of a drive motor (not shown) is applied to the first gear 15 provided in the differential case 14 . The first output shaft 11 and the second output shaft 12 are drive shafts of the automobile. The power transmission device 10 transmits the torque of the drive motor to the left and right wheels via the first output shaft 11 and the second output shaft 12, and transmits the torque to the left and right wheels while allowing a difference in rotational speed between the left and right wheels. Actively allocate.

The first planetary gear device 20 includes a first element 21 , a second element 22 and a third element 24 that rotate in conjunction with the first element 21 . The rotation of the second element 22 and the third element 24 in conjunction with the first element 21 refers to a state before the planetary gear set 20 is assembled to the power transmission device 10. After the planetary gear device 20 is assembled to the power transmission device 10, rotation of any one of the elements 21, 22, and 24 is restricted. In this embodiment, the second element 22 is a sun gear, and the third element 24 is a ring gear arranged coaxially with the sun gear. The first element 21 is a carrier that supports a planetary gear 23 that meshes with the sun gear and ring gear.

The first element 21 is coupled to the first output shaft 11 , which passes through the second element 22 . The third element 24 is provided with an annular second gear 25 that is continuous in the circumferential direction. The second element 22 is provided with an annular third gear 26 that is continuous in the circumferential direction. A fourth gear 27 that meshes with the third gear 26 is coupled to a rotating shaft of a control motor 28 . Torque (control torque) of a control motor 28 is applied to the second element 22 through meshing between a third gear 26 and a fourth gear 27 (reduction device).

The second planetary gear device 30 includes a first element 31, a second element 32 that rotates in conjunction with the first element 31, and a third element 34. The rotation of the second element 32 and the third element 34 in conjunction with the first element 31 refers to a state before the planetary gear set 30 is assembled to the power transmission device 10. After the planetary gear device 30 is assembled to the power transmission device 10, rotation of any one of the elements 31, 32, and 34 is restricted. In this embodiment, the second element 32 is a sun gear, and the third element 34 is a ring gear disposed coaxially with the sun gear. The first element 31 is a carrier that rotatably supports a planetary gear 33 that meshes with the sun gear and the ring gear.

The first element 31 is coupled to the second output shaft 12 , and the second output shaft 12 passes through the second element 32 . The third element 34 is provided with an annular fifth gear 35 that is continuous in the circumferential direction. The second element 32 is provided with a rotating body 36 that rotates together with the second element 32. The rotating body 36 is fixed to a stationary body 41 such as a case (not shown) of the power transmission device 10 by friction. Therefore, the rotation of the second element 32 of the second planetary gear set 30 is restricted.

The speed transmission ratio of the first planetary gear unit 20 when the second element 22 of the first planetary gear unit 20 is fixed, the first element 21 is the input shaft, and the third element 24 is the output shaft is , the speed transmission ratio of the second planetary gear device 30 when the second element 32 of the second planetary gear device 30 is fixed, the first element 31 is the input shaft, and the third element 34 is the output shaft is the same value. That is, the first planetary gear device 20 and the second planetary gear device 30 differ only in the positions where they are arranged, and the number of teeth and the number of each element are the same. The number of teeth of the second gear 25 is the same value as the number of teeth of the fifth gear 35.

The differential gear 13 is arranged between the first planetary gear set 20 and the second planetary gear set 30. In this embodiment, the first planetary gear set 20 and the second planetary gear set 30 are arranged symmetrically with respect to the differential gear 13. The sun gear of the first planetary gear set 20 and the sun gear of the second planetary gear set 30 are arranged symmetrically with respect to a plane 42 that includes the rotation axis 19 of the pinion 18 of the differential gear 13 .

In the power transmission device 10, a connecting portion 37 that connects the third elements 24 and 34 is arranged between the first planetary gear device 20 and the second planetary gear device 30. The connecting portion 37 includes a sixth gear 38 that meshes with the second gear 25 provided on the third element 24 and a seventh gear 39 that meshes with the fifth gear 35 provided on the third element 34. , a shaft 40 that connects the sixth gear 38 and the seventh gear 39 and rotates together with the sixth gear 38 and the seventh gear 39. The number of teeth of the sixth gear 38 is the same value as the number of teeth of the seventh gear 39. Since the position of the shaft 40 is fixed, in this embodiment the coupling portion 37 causes the third elements 24, 34 to rotate in the same direction and at the same speed.

When the carrier (first element 21) supporting the planetary gear 23 meshing with the sun gear of the first planetary gear set 20 attempts to rotate the sun gear (second element 22) to which the control motor 28 is attached, the second The rotational speed of element 22 tends to be greater than the rotational speed of first element 21. Since the torque acting on each element is inversely proportional to the rotation speed, the torque of the second element 22 can be lower than the torque of the first element 21. A control motor 28 having an inertia sufficient to regulate rotation of the second element 22 with reduced torque is attached to the second element 22. That is, the rotation of the second element 22 is regulated by the control motor 28.

When a car equipped with the power transmission device 10 is traveling straight at high speed on an uneven road such as a cobblestone road, one wheel (not shown) momentarily leaves the road surface, floats in the air, and lands again. There are things to do. Even when one wheel is suspended in the air, the drive motor (not shown) continues to supply torque to the differential device 13, so the wheel suspended in the air spins, the differential device 13 is activated, and the wheel is A situation arises in which the rotational speeds between the first elements 21, 31 to which the attached output shafts 11, 12 are coupled must be significantly different.

However, the rotation of the second element 32 of the second planetary gear set 30 is restricted, and the third element 34 is connected to the third element 24 of the first planetary gear set 20 via a connecting portion 37. A control motor 28 is attached to the second element 22 through meshing between a third gear 26 and a fourth gear 27 (reduction gear). Therefore, when the differential 13 operates with one wheel in the air, the second element 22 of the first planetary gear 20 drives the control motor 28 in reverse, or the second planetary gear The second element 32 of the device 30 is in a state where it attempts to rotate against the frictional force acting between the stationary body 41 and the rotating body 36.

When the first element 31 (carrier) of the second planetary gear device 30 rotates at a certain speed, the rotation speed of the second element 32 (sun gear) is greater than the rotation speed of the first element 31. , the torque of the second element 32 and the rotating body 36 is smaller than the torque of the first element 31. Therefore, the rotation of the second element 32 is regulated by a certain amount of frictional force acting between the rotating body 36 and the stationary body 41.

In order for the second element 22 of the first planetary gear set 20 to reversely drive the control motor 28, it must drive a large inertia obtained by multiplying the inertia of the control motor 28 by the square of the reduction ratio of the reduction gear. Must be. Therefore, even if one wheel floats for a short period of time, the rotational speed of the wheel suspended in the air will hardly change. That is, the first planetary gear set 20 and the second planetary gear set 30 realize an inertial limited slip differential. Even if one wheel is suspended in the air, the rotational speed of the left and right wheels remains almost the same, so driving torque continues to be applied to the wheels that are on the ground. Even when a wheel floats in the air and lands, both wheels continue to drive the vehicle, ensuring straight-line stability. Since the rotational speed of the wheel suspended in the air is almost the same as the rotational speed of the wheel when it was on the ground, no excessive force is exerted on each gear of the power transmission device 10 when the wheel lands again. Therefore, the risk of damage to each gear of the power transmission device 10 can be reduced.

When the control motor 28 is activated when a crosswind blows while the vehicle is traveling straight or when turning, torque is transmitted in the direction of rotating the first side gear 16 and the second side gear 17 in opposite directions. Since the torque is applied to the device 10, the torque on one of the output shafts 11 and 12 increases, and the torque on the other output shaft 11 and 12 decreases. This makes it possible to control the yaw moment around the center of gravity, which is a control parameter when the vehicle attempts to turn. Since the planetary gear devices 20 and 30 are arranged on the two output shafts 11 and 12, respectively, it is possible to reduce the weight deviation and drive torque deviation of the power transmission device 10 with the differential device 13 as a boundary. Therefore, the running stability of the automobile can be improved.

When the control motor 28 is operated, the second element 22 rotates through meshing with the third gear 26 and the fourth gear 27, and as the planetary gear 23 revolves, the first element 21 rotates. Torque is applied to the power transmission device 10 in a direction that causes the side gear 16 and the second side gear 17 to rotate in opposite directions. Since this operation is achieved through gear meshing, the magnitude and direction of torque can be controlled with almost no hysteresis, and driving force can be actively distributed to the left and right wheels with precision.

Since the second element 32 of the second planetary gear device 30 is fixed to the stationary body 41 by friction, a torque that exceeds the frictional force acting between the rotating body 36 and the stationary body 41 is applied to the second element 32. The second element 32 is stationary unless applied. When the torque of the second output shaft 12 becomes excessive and a torque exceeding the frictional force acting between the rotating body 36 and the stationary body 41 is applied to the second element 32, the second element 32 rotates. Thereby, when excessive torque is applied to the power transmission device 10, it is possible to prevent excessive impact force from acting on each gear of the power transmission device 10. Therefore, the risk of damage to the power transmission device 10 can be reduced.

Since the control motor 28 is attached to the second element 22 (sun gear) whose torque is smaller than the torque of the first element 21 (carrier) to which the first output shaft 11 is coupled, the control motor 28 is relatively small. Torque can be applied to the power transmission device 10 with a small torque (control torque). Therefore, the control motor 28 can be one with a small maximum torque.

The differential device 13 includes a first side gear 16 coupled to the first output shaft 11, a second side gear 17 coupled to the second output shaft 12, and the first side gear 16 and the second side gear 17. It includes a pinion 18 that meshes with the pinion 18, and a differential case 14 that supports the rotation axis 19 of the pinion 18. As a result, compared to a differential device including a planetary gear device, it is possible to reduce bias in the efficiency of distributing torque between the first output shaft 11 and the second output shaft 12. Furthermore, a torque vectoring function can be added to the existing differential gear 13.

Since the first planetary gear device 20 and the second planetary gear device 30 are arranged symmetrically with respect to the differential device 13, the symmetry of the power transmission device 10 with respect to the differential device 13 can be improved. Furthermore, since the first output shaft 11 and the second output shaft 12 can be made to have the same length, maneuverability can be improved. In particular, the sun gear of the first planetary gear set 20 and the sun gear of the second planetary gear set 30 are arranged symmetrically with respect to the plane 42 that includes the rotation axis 19 of the pinion 18 of the differential gear 13, so that the symmetry is further enhanced. You can improve. Moreover, since the central axis O of the differential device 13 and the rotation centers of the planetary gear devices 20 and 30 are arranged coaxially, the radial dimension of the power transmission device 10 can be prevented from becoming excessive.

Although the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments in any way, and it is easily understood that various improvements and modifications can be made without departing from the spirit of the present invention. This can be inferred.

Although the embodiment has described the differential device 13 including two side gears 16 and 17 made of bevel gears and a pinion 18 that meshes with the side gears 16 and 17, the present invention is not necessarily limited to this. Instead of the differential device 13 including a bevel gear, it is of course possible to employ a known mechanism including a planetary gear device as the differential device 13.

In the embodiment, a case has been described in which the first planetary gear device 20 and the second planetary gear device 30 include a single planetary gear train, but the invention is not necessarily limited to this. It is of course possible to employ a composite planetary gear train, which is a combination of a plurality of single planetary gear trains, for the first planetary gear set 20 and the second planetary gear set 30, respectively.

In the embodiment, in the first planetary gear set 20, a control motor 28 is attached to the sun gear as the second element 22, a ring gear is connected to the second planet gear set 30 as the third element 24, and the second planet In the gear device 30, a case has been described in which the rotation of the sun gear is regulated via the rotating body 36 as the second element 32, and the ring gear is connected to the first planetary gear device 20 as the third element 34. However, it is not limited to this.

For example, in the first planetary gear set 20, the control motor 28 is attached to the ring gear as the second element 22, and the sun gear is connected as the third element 24 to the second planetary gear set 30. Of course, it is possible to restrict the rotation of the ring gear as the second element 32 via the rotating body 36 and to connect the sun gear to the first planetary gear set 20 as the third element 34.

In the embodiment, in the first planetary gear device 20 and the second planetary gear device 30, the carrier is coupled to the first output shaft 11 and the second output shaft 12 as the first elements 21 and 31, respectively. explained. However, it is not limited to this.

For example, in the first planetary gear device 20 and the second planetary gear device 30, it is naturally possible to couple ring gears as the first elements 21 and 31 to the first output shaft 11 and the second output shaft 12, respectively. be. In this case, for example, in the first planetary gear set 20, the control motor 28 is attached to the sun gear as the second element 22, the carrier is connected to the second planet gear set 30 as the third element 24, and the control motor 28 is attached to the sun gear as the second element 22. In the gear system 30 , a second element 32 regulates the rotation of the sun gear via a rotating body 36 , and a third element 34 connects the carrier to the first planetary gear system 20 .

Furthermore, in the first planetary gear device 20 and the second planetary gear device 30, it is naturally possible to couple the sun gear as the first elements 21 and 31 to the first output shaft 11 and the second output shaft 12, respectively. It is. In this case, for example, in the first planetary gear set 20, the control motor 28 is attached to the ring gear as the second element 22, the carrier is connected to the second planet gear set 30 as the third element 24, and the control motor 28 is attached to the ring gear as the second element 22. In the gear system 30 , a second element 32 regulates the rotation of the ring gear via a rotating body 36 , and a third element 34 connects the carrier to the first planetary gear system 20 .

In the embodiment, a case has been described in which the second element 32 of the second planetary gear device 30 is fixed to the stationary body 41 by friction, but the invention is not necessarily limited to this. It is of course possible to fix the second element 32 to the stationary body 41 by mechanical or metallurgical bonding. Examples of mechanical connections include connections using screws, rivets, caulking, and spline connections. Examples of metallurgical joining include joining by welding and brazing.

In the embodiment, a case has been described in which the control motor 28 is attached to the second element 22 through meshing between the third gear 26 and the fourth gear 27 (reduction gear), but this is not necessarily the case. It's not a thing. As long as the inertia of the control motor 28 is ensured, it is naturally possible to omit the reduction gear and connect the rotation shaft of the control motor 28 and the second element 22 coaxially. The radial dimension of the power transmission device 10 can be reduced to the extent that the speed reduction device can be omitted.

In the embodiment, a case has been described in which wheels are attached to each of the first output shaft 11 and the second output shaft 12, that is, a case in which the power transmission device 10 is provided on the drive shaft extending from left to right of the automobile, but this is not necessarily the case. It is not limited. It is naturally possible to arrange the first output shaft 11 and the second output shaft 12 so as to extend in the front and rear of the automobile, and to provide the power transmission device 10 on the drive shaft (propeller shaft) that extends in the front and rear. In this case, the power transmission device 10 adjusts the torque distribution between the front and rear wheels.

In the embodiment, a case has been described in which the driving force of a drive motor (not shown) is applied to the differential device 13, but the invention is not necessarily limited to this. Of course, it is possible to apply the driving force of the engine to the differential device 13. In this case, it is naturally possible to interpose a transmission between the engine and the differential gear 13.

10 Power transmission device 11 First output shaft 12 Second output shaft 13 Differential device 14 Differential case 16 First side gear 17 Second side gear 18 Pinion 19 Rotating shaft 20 First planetary gear device 21 First element ( carrier)
22 Second element (sun gear)
23 Planetary gear 24 Third element (ring gear)
28 Control motor 30 Second planetary gear device 31 First element (carrier)
32 Second element (sun gear)
33 Planetary gear 34 Third element (ring gear)
37 Connecting part 41 Stationary body O Central axis

Claims (4)

a differential device that distributes drive torque to a first output shaft and a second output shaft;
A first planetary gear device and a second planetary gear device each including a first element, a second element, and a third element that rotate in conjunction with the first element;
a connecting portion that connects the third element of the first planetary gear device and the third element of the second planetary gear device,
the first output shaft is coupled to the first element of the first planetary gear set;
the second output shaft is coupled to the first element of the second planetary gear set;
a control motor is attached to the second element of the first planetary gearing;
The second element of the second planetary gear device is a power transmission device whose rotation is restricted. The power transmission device according to claim 1, wherein the second element of the second planetary gear device is fixed to a stationary body by friction. The power transmission device according to claim 1 or 2, wherein the first element is a carrier that rotatably supports a planetary gear that meshes with a sun gear and a ring gear. The power transmission device according to claim 1 or 2, wherein the first planetary gear device and the second planetary gear device are arranged symmetrically with respect to the differential device.

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