JP2010185486A - Drive unit for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit for a vehicle capable of distributing a driving force to one side to the other side even when left and right wheels tread. <P>SOLUTION: This drive unit 2 includes a differential mechanism 7 having the first differential gear 8L differential-rotated each other, the second differential gear 8R and a case 10, the first electric motor 3L interposed between a left driving wheel 4L and the first differential gear 8L, the second electric motor 3R interposed between a right driving wheel 4R and the second differential gear 8R, and a central brake BC capable of braking and releasing the case 10 of the differential mechanism 7, an outer 13L of the first electric motor 3L is connected to the first differential gear 8L, and an outer 13R of the second electric motor 3R is connected to the second differential gear 8R. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle driving device in which braking / driving means for applying braking / driving force to driving wheels of a vehicle is interposed between a differential mechanism and driving wheels.

  2. Description of the Related Art A vehicle drive device is known in which in-wheel motors are provided on left and right drive wheels and a differential mechanism is disposed between the drive wheels (Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP 2000-177411 A JP 2008-193844 A JP 2008-57549 A

  In the drive device of Patent Document 1, since the case that is a reaction force element of the in-wheel motor is fixed to the vehicle body, when one drive wheel of the left and right drive wheels idles, the drive force is transferred to the other drive wheel. Can only be distributed. For this reason, the driving force cannot be distributed during normal traveling or when both driving wheels are in contact with the ground.

  Therefore, an object of the present invention is to provide a vehicle drive device that can distribute a drive force to one side to the other even when the left and right drive wheels are grounded.

  The drive device of the present invention includes a differential mechanism having three rotation elements that can rotate differentially with each other, one of the first drive wheels of the left and right drive wheels of the vehicle, and any one of the three rotation elements. A first braking / driving means that is interposed between two first rotating elements and can apply braking / driving force to the first driving wheel; the other second driving wheel of the left and right driving wheels; and the three rotations A second braking / driving means that is interposed between another second rotating element of the element and can apply a braking / driving force to the second driving wheel; and the remaining third rotating element of the three rotating elements. Braking means capable of braking and releasing the first braking / driving means, wherein the first braking / driving means is a first reaction force element that receives a reaction force of the braking / driving force applied to the first driving wheel, and the second braking / driving means is the A second reaction force element that receives a reaction force of the braking / driving force applied to the second drive wheel, and the first reaction force element is the first reaction force element; A rotating element, the second reaction force elements are respectively connected to the second rotating element, those (claim 1).

  According to this drive device, both the first driving wheel and the second driving wheel are driven in the same direction by the first braking / driving means and the second braking / driving means with the third rotating element braked by the braking means. By applying force, the reaction force of each braking / driving device is input to the first rotating element and the second rotating element of the differential mechanism. Therefore, when a difference occurs in the braking / driving force applied to each drive wheel, the differential driving mechanism absorbs the difference in braking / driving force by differentially rotating each rotating element. That is, even when a difference in braking / driving force occurs between the left and right driving wheels while both driving wheels are grounded, one braking / driving force can be distributed to the other by the differential mechanism. A differential rotation between the first rotation element and the second rotation element causes a rotation difference in each reaction force element, and allows a difference in rotation speed of each drive wheel due to the braking / driving force difference. Accordingly, even if the rotation of the first driving wheel and the rotation of the second driving wheel are not separately controlled by each braking / driving means, the traveling of the vehicle is stabilized by the function of the differential mechanism. Further, when the third rotating element is released by the braking means while each driving wheel is stopped, such as when the vehicle is stopped, each reaction force of the first braking / driving means and the second braking / driving means is It is received by each drive wheel. For this reason, since the braking / driving force of each braking / driving means can be output from the third rotating element, the power can be used when the vehicle is stopped.

  One aspect of the present invention may further include wheel braking means capable of independently braking each of the first drive wheel and the second drive wheel. According to this aspect, by braking one of the first driving wheel or the second driving wheel, the reaction force of the braking / driving means provided on the one driving wheel side is increased, and the increase is the other side. It is distributed to the drive wheel side. Thereby, the rotational speed of the other drive wheel can be increased. That is, the output ratio of each braking / driving means can be adjusted by appropriately adjusting the braking force of each driving wheel.

  The braking / driving means may take any form as long as it is interposed between the drive wheel and the rotating element of the differential mechanism. For example, the braking / driving means may be configured in the form of a so-called harmonic drive in which an electric motor is disposed in the middle of an axle shaft or a drive shaft, and at least one of the first braking / driving means and the second braking / driving means. One of them may be configured as an in-wheel motor (claim 3). In this case, only one of the braking / driving means may be configured as an in-wheel motor, or both the braking / driving means may be configured as an in-wheel motor.

  The power output from the third rotating element of the differential mechanism may be used in any way. For example, the vehicle is provided with a steering assist device for assisting steering of the first drive wheel and the second drive wheel, while the first drive wheel and the second drive wheel are provided in a steerable state. The power of the third rotating element of the differential mechanism may be used as a drive source for the steering assist device (claim 4). According to this aspect, it is possible to assist the steering by using the power output from the third rotating element at the time of the stationary operation that is the steering while the vehicle is stopped. For this reason, the assistance at the time of stationary can be performed by the power of the third rotating element, so that there is an advantage that the capacity of the drive device to be mounted on the steering assist device in order to assist the steering during traveling can be reduced.

  In this aspect, the steering assist device includes a steering assist member that assists steering of the first drive wheel and the second drive wheel, and is interposed between the steering assist member and the third rotation element. A power transmission mechanism for transmitting the power of the third rotating element to the steering assist member, and the power transmission mechanism is configured to be capable of switching the direction of the power transmitted to the steering assist member between the forward and reverse directions. (Claim 5). In this case, even if the rotation direction of the third rotation element is one direction, it is possible to switch the direction of the power transmitted by the power transmission mechanism to the steering assist member according to the steering direction. That is, even when the vehicle is traveling in which the operation direction of each braking / driving means cannot be changed, power can be extracted from the third rotating element and used for steering assistance.

  In the present invention, applying braking / driving force means applying force to a driving wheel as an operation target, and is a concept including both driving in which positive acceleration occurs and braking in which negative acceleration occurs.

  As described above, according to the drive device of the present invention, even when a braking / driving force difference occurs between the left and right drive wheels with both drive wheels in contact with each other, each rotating element rotates differentially. Thus, the braking force difference is absorbed by the differential mechanism, so that one braking / driving force can be distributed to the other by the differential mechanism.

The figure which showed typically the front principal part of the vehicle to which the drive device which concerns on a 1st form was applied. The figure which showed typically the front principal part of the vehicle to which the drive device which concerns on a 2nd form was applied. The figure which showed typically the front principal part of the vehicle to which the drive device which concerns on a 3rd form was applied.

(First form)
FIG. 1 schematically shows a front main part of a vehicle to which a driving apparatus according to a first embodiment of the present invention is applied. The upper side of FIG. 1 corresponds to the front side of the vehicle. The vehicle 1A is configured as an electric vehicle using an electric motor as a driving power source. The drive device 2 is mounted on the vehicle 1A and brakes and drives the left and right drive wheels 4L and 4R with a pair of left and right electric motors 3L and 3R. This braking / driving means applying a force to the drive wheel, and includes both a drive applying a force in the rotational direction of the drive wheel and a braking applying a force in the opposite direction. Each drive wheel 4L, 4R has wheels 5L, 5R, and axles 6L, 6R are connected to each wheel 5L, 5R. A differential mechanism 7 is provided between the drive wheels 4L and 4R. The differential mechanism 7 has three rotating elements that can be differentially rotated with respect to each other. That is, the differential mechanism 7 includes a first differential gear 8L configured as a bevel gear, a second differential gear 8R configured coaxially with the first differential gear 8L and configured as a bevel gear, A case 10 that rotatably holds a pair of pinions 9 that mesh with the differential gears 8L and 8R, respectively. A ring gear 11 configured as a bevel gear coaxial with the differential gears 8L and 8R is provided on the outer periphery of the case 10.

  The first motor 3L is interposed between the first drive wheel 4L and the differential mechanism 7, and the second motor 3R is interposed between the second drive wheel 4R and the differential mechanism 7. The first electric motor 3L includes a rotor 12L connected to one end of the axle 6L, and an outer 13L disposed on the outer periphery of the rotor 12L. The rotor 12L and the outer 13L are provided in a relatively rotatable state. . The outer 13L is connected to the first differential gear 8L via a connecting shaft 14L. Accordingly, when the first electric motor 3L is operated, a braking / driving force is applied to the first driving wheel 4L, and the reaction force is transmitted through the outer differential 13L and the connecting shaft 14L as the first differential gear 8L. Is input. Accordingly, the first motor 3L corresponds to the first braking / driving means according to the present invention, the first differential gear 8L corresponds to the first rotating element according to the present invention, and the outer 13L corresponds to the first reaction force element according to the present invention. To do.

  On the other hand, the second electric motor 3R similarly has a rotor 12R connected to one end of the axle 6R and an outer 13R disposed on the outer periphery of the rotor 12R, and these are provided in a relatively rotatable state. Yes. The outer 13R is connected to the second differential gear 8R via a connecting shaft 14R. As a result, when the second electric motor 3R is operated, a braking / driving force is applied to the second driving wheel 4R, and the reaction force is applied to the second differential gear 8R via the outer 13R and the connecting shaft 14R which are reaction force elements. Is input. Accordingly, the second motor 3R corresponds to the second braking / driving means according to the present invention, the second differential gear 8R corresponds to the second rotating element according to the present invention, and the outer 13R corresponds to the second reaction force element according to the present invention. To do. The case 10 which is the remaining rotating element of the differential mechanism 7 corresponds to a third rotating element according to the present invention. The ring gear 11 provided in the case 10 meshes with a speed increasing gear 15 configured as a bevel gear having a smaller number of teeth than that, and the speed increasing gear 15 is provided so as to rotate integrally with the output shaft 16. Yes.

  Wheel brakes BL and BR are provided on the left and right drive wheels 4L and 4R. The left wheel brake BL has a brake disk 20L that rotates integrally with the first drive wheel 4L, and a brake caliper 21L that operates between a braking position that sandwiches the brake disk 20L and a release position that releases the brake disk 20L. . Similarly, the right wheel brake BR has a brake disc 20R that rotates integrally with the second drive wheel 4R, and a brake caliper 21R that operates between a braking position that sandwiches the brake disc 20R and a release position that releases the brake disc 20R. ing. Each caliper 21L, 21R is attached to a vehicle body constituent member of the vehicle 1A.

  Each wheel brake BL, BR can be operated independently. For example, it is possible to brake the first driving wheel 4L while releasing the second driving wheel 4R, or to operate in the opposite state. Of course, it is also possible to brake and release each drive wheel 4L, 4R simultaneously. Accordingly, when the left and right wheel brakes BL and BR are combined, they function as the wheel braking means according to the present invention. The drive device 2 is provided with a central brake BC as a braking means for braking and releasing the case 10 of the differential mechanism 7. The central brake BC operates between a braking position where the ring gear 11 provided in the case 10 is sandwiched and a release position where the ring gear 11 is released. The central brake BC is attached to the vehicle body constituent member.

  The brakes BL, BR, BC are controlled in operation by a brake control device (not shown). For example, during traveling of the vehicle 1A, the case 10 is braked by the central brake BC, and this is stopped with respect to the vehicle body. Thereby, since the reaction force of each motor 3L, R is received by the differential mechanism 7, each drive wheel 4L, 4R is rotationally driven in the direction of the arrow Df shown. When a driving force difference (a reaction force difference from the road surface) occurs between the left and right driving wheels 4L and 4R while the vehicle 1A is traveling, the outer mechanisms 13L and 13R are rotated reversely (differential by the differential mechanism 7). Rotation), one driving force is distributed to the other, and the driving force difference is absorbed. Thereby, a rotation difference between the drive wheels 4L and 4R can be allowed. This is the same when the drive wheels 4L and 4R are braked. Therefore, it is possible to secure the running stability by using the function of the differential mechanism 7 without separately controlling the rotational speeds of the drive wheels 4L and 4R by the electric motors 3L and 3R. In other words, the drive device 2 can use the function of the differential mechanism 7 in the same manner as a normal drive device that distributes engine power to the left and right drive wheels via the differential mechanism. Further, by braking one of the drive wheels 4L and 4R using the wheel brakes BL and BR, the reaction force of the electric motor provided on one of the drive wheels increases, and the increase The minute is distributed to the other drive wheel side. Thereby, the rotational speed of the other drive wheel can be increased. That is, it is possible to adjust the output ratio of each electric motor 3L, 3R by appropriately adjusting the braking force of each drive wheel 4L, 4R.

  While the vehicle 1A is stopped, the drive wheels 4L and 4R are braked by the wheel brakes BL and BR, and the case 10 of the differential device 7 is released by the central brake BC. By operating the electric motors 3L and 3R in this state, the reaction force of the electric motors 3L and 3R is received by the drive wheels 4L and 4R. Therefore, the power of the electric motors 3L and 3R is supplied to the differential mechanism 7 and the speed increasing gear. 15 through the output shaft 16. Therefore, the power output from the output shaft 16 when the vehicle 1A is stopped can be used. When the power output from each of the motors 3L and 3R is small, each drive is driven by the frictional force generated between the drive wheels 4L and 4R and the road surface when the vehicle is stopped without braking the wheel brakes BL and BR. Since the reaction forces of the electric motors 3L and 3R can be received by the wheels 4L and 4R, the power of the electric motors 3L and 3R can be taken out from the output shaft 16.

(Second form)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 schematically shows a front main part of a vehicle to which the drive device according to the second embodiment is applied. In the following, the same reference numerals are attached to the same components as those in the first embodiment, and the description thereof is omitted. In this embodiment, power output from the output shaft 16 is used as a drive source for the steering assist device. The vehicle 1B is provided with a steering mechanism 25 for steering the left and right drive wheels 4L, 4R. Further, in order to be able to steer each drive wheel 4L, 4R, each connecting shaft 14L, 14R is divided into two parts, and each divided part is connected by connecting parts 26L, 26R which can transmit rotation in a state where the angle can be changed. ing. Accordingly, each drive wheel 4L, 4R is attached to the vehicle in a steerable state. The steering mechanism 25 is configured as a rack-and-pinion-type steering mechanism, and includes a rack 27 in which a tooth portion 27a is engraved and extends in the left-right direction, a pair of arms 28L and 28R linked to both sides of the rack 27, and a steering. And a steering assist device 29 for assisting the force. The steering arms 28L and 28R are coupled to the coupling shafts 14L and 14R so that the coupling shafts 14L and 14R can be tilted in a rotatable state. The steering assist device 29 uses the power of the case 10 of the differential mechanism 7, in other words, the power of the output shaft 16 as a part of its drive source. That is, the pinion 30 provided on the output shaft 16 meshes with the tooth portion 27 a of the rack 27, so that the power of the case 10 is transmitted to the rack 27. The steering mechanism 25 is provided with a transmission mechanism 32 that transmits the rotation of the steering wheel 31 to the rack 27, and the transmission mechanism 32 is provided with an electric motor 33 that is another drive source of the steering assist device 29. .

  When the output shaft 16 rotates in the direction indicated by the arrow D1, an assisting force that moves the rack 27 in the left direction works, so that left steering can be assisted. On the other hand, when the output shaft 16 rotates in the direction indicated by the arrow D2, the right steering can be assisted. Thus, in order to assist left and right steering, it is necessary to switch the rotation direction of the output shaft 16. In order to switch the rotation direction, it is necessary to switch the rotation direction of each of the electric motors 3L and 3R, but the rotation direction of each of the electric motors 3L and 3R cannot be switched during traveling. Therefore, the steering assist device 29 according to the present embodiment can use the power of the output shaft 16 as an assist when the vehicle is stationary while the vehicle is stopped. Since the steering force at the time of stationary is greater than that during traveling, it is sufficient that the electric motor 33 incorporated in the steering assist device 29 can assist steering during traveling by using the power of the output shaft 16 at the time of stationary. Therefore, the electric motor 33 can be reduced in size.

(Third form)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 schematically shows a front main part of a vehicle to which the drive device according to the second embodiment is applied. This form is equivalent to the modification which changed the direction of the steering auxiliary force of the 2nd form so that change was possible. Hereinafter, the same reference numerals are given to components common to the second embodiment, and description thereof will be omitted. The vehicle 1 </ b> C shown in FIG. 3 is provided with a steering assist device 35 that assists the steering mechanism 25 in steering.

  The steering assist device 35 is provided between the first output shaft 16A provided with the speed increasing gear 15, the second output shaft 16B provided with the pinion 30 engaged with the tooth portion 27a of the rack 27, and the output shafts 16A and 16B. The rotation switching mechanism 36 is provided. The rotation switching mechanism 36 has the same structure as that of the differential mechanism 7, and is arranged coaxially with the first differential gear 41 provided on the first output shaft 16A and the first differential gear 41. A second differential gear 42 provided on the output shaft 16B and a case 44 that rotatably holds a pair of pinions 43 that mesh with the differential gears 41 and 42, respectively. Further, the rotation switching mechanism 36 releases the brake Ba, which operates between a braking position where the case 44 is restrained to the vehicle body and a release position where the case 44 is released, and an engagement position where the pinion 43 is restrained with respect to the case 44. And a clutch CL that operates between the release position and the release position.

  By appropriately operating the brake Ba and the clutch CL of the rotation switching mechanism 36, the state where the first output shaft 16A and the second output shaft 16B rotate in the same direction, and the state where they rotate in the opposite directions Can be switched. That is, when the brake Ba is operated to the release position while the clutch CL is operated to the engaged position, the differential rotation of the differential gears 41 and 42 is prevented and the output shafts 16A and 16B are moved in the same direction together with the case 44. Rotates together. On the other hand, when the brake Ba is operated to the braking position while the clutch CL is operated to the release position, the differential gears 41 and 42 are differentially rotated in opposite directions, so that the output shafts 16A and 16B are rotated in opposite directions. To do. Therefore, even if the rotation direction of the first output shaft 16A is one direction, the rotation switching mechanism 36 causes the left steering assist to rotate the second output shaft 16B in the direction of the arrow D1, and the second output shaft 16B to the arrow D2. It is possible to achieve both the right steering assistance that rotates in the direction of. In other words, steering assistance in both directions can be performed without switching the rotation directions of the electric motors 3L and 3R. Therefore, not only when the vehicle 1 </ b> C is stopped but also when the vehicle is running, steering can be assisted by appropriately operating the rotation switching mechanism 36. Thereby, since all the drive sources of the steering assist device 35 can be replaced with the respective electric motors 3L, 3R, the auxiliary electric motor 33 (FIG. 2) mounted in the second mode can be omitted.

  In the third embodiment, the ring gear 11, the speed increasing gear 15, the first output shaft 16A, the rotation switching mechanism 36, the second gear are provided between the rack 27 serving as a steering assist member and the case 10 of the differential mechanism 7. A power transmission element group including the output shaft 16B and the pinion 30 is interposed, the power of the case 10 can be transmitted to the rack 27 by the power transmission element group, and the power transmitted to the rack 27 is switched between the forward and reverse directions. Can do. Therefore, the power transmission element group of the present embodiment functions as power transmission means according to the present invention.

  The present invention is not limited to the above embodiments, and can be implemented in various forms within the scope of the gist of the present invention. It is also possible to implement at least one of the first braking / driving means and the second braking / driving means according to the present invention as an in-wheel motor of a type in which an electric motor is disposed on the inner peripheral side of the drive wheel. That is, both or only one of the first braking / driving means and the second braking / driving means can be configured as an in-wheel motor. In the second and third embodiments, the power of the case, which is the third rotating element of the differential mechanism, is used as a drive source of the steering assist device, but there is no limitation on the method of using the power. Therefore, it is possible to use the power as a drive source for a work device such as a winch. In addition, the differential mechanism is configured as a planetary gear mechanism, and the differential mechanism can be configured as a planetary roller mechanism using a friction wheel as a rotating element.

1A to 1C Vehicle 2 Driving device 7 Differential mechanism 3L First electric motor (first braking / driving means)
3R second electric motor (second braking / driving means)
4L drive wheel (first drive wheel)
4R drive wheel (second drive wheel)
8L first differential gear (first rotating element)
8R Second differential gear (second rotating element)
10 Case (third rotating element)
13L outer (first reaction force element)
13R outer (second reaction force element)
27 Rack (steering assisting member)
29, 35 Steering assist device BL Wheel brake BR Wheel brake BC Central brake (braking means)

Claims (5)

A differential mechanism having three rotational elements capable of differentially rotating with each other, a first drive wheel of one of the left and right drive wheels of the vehicle, and a first rotational element of any one of the three rotational elements. A first braking / driving means capable of applying a braking / driving force to the first driving wheel interposed therebetween, a second driving wheel of the other of the left and right driving wheels, and another one of the three rotating elements. A second braking / driving means that is interposed between the two rotating elements and can apply braking / driving force to the second driving wheel, and a brake capable of braking and releasing the remaining third rotating element of the three rotating elements. Means, and
The first braking / driving means has a first reaction force element that receives a reaction force of the braking / driving force applied to the first driving wheel, and the second braking / driving means has a reaction force of the braking / driving force applied to the second driving wheel. The vehicle has a second reaction force element to be received, the first reaction force element being connected to the first rotation element, and the second reaction force element being connected to the second rotation element, respectively. Drive device.   The drive device according to claim 1, further comprising wheel braking means capable of independently braking each of the first drive wheel and the second drive wheel.   The drive device according to claim 1 or 2, wherein at least one of the first braking / driving means and the second braking / driving means is configured as an in-wheel motor. In the vehicle, the first drive wheel and the second drive wheel are provided in a steerable state, and a steering assist device for assisting steering of the first drive wheel and the second drive wheel is provided. ,
The drive device according to any one of claims 1 to 3, wherein power of the third rotation element of the differential mechanism is used as a drive source of the steering assist device. The steering assist device includes a steering assist member for assisting steering of the first drive wheel and the second drive wheel, and the third rotation element interposed between the steering assist member and the third rotation element. Power transmission means for transmitting the power of the power to the steering assist member,
The drive device according to claim 4, wherein the power transmission means is configured to be able to switch a direction of power transmitted to the steering assist member between two directions of forward and reverse.

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