JP2018154232A - Drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive device that has a parking lock function and enables an entire apparatus to be downsized.SOLUTION: A drive apparatus includes: a motor 2 that rotates about a shaft coaxial with a rotational axis of a wheel; a speed reduction mechanism 7, connected to the motor 2 and wheel, for transmitting torque to the wheel by increasing torque of the motor 2; and a brake mechanism 19 connected to an input side of the speed reduction mechanism 7. Further, the brake mechanism 19 includes: a brake rotor 20 connected to the speed reduction mechanism 7; a brake stator 21 for applying brake torque to the brake rotor 20 by frictionally contacting the brake rotor 20; a first electromagnetic actuator 22 capable of controlling contact pressure between the brake stator 21 and brake rotor 20; and a second electromagnetic actuator 26 capable of maintaining a state of the brake stator 21 and brake rotor being contacted with given contact pressure even with a power supply of the vehicle being cut off.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a driving device that applies driving torque and braking torque to wheels, and more particularly to a driving device provided for each of a plurality of wheels.

  Patent Document 1 and Patent Document 2 describe a so-called in-wheel drive device in which a motor is mounted in a tire wheel. In these drive devices, a reduction gear is provided in a torque transmission path between the motor and the tire wheel in order to reduce the size of the motor. This speed reducer is constituted by two single pinion type planetary gear mechanisms. In the drive device described in Patent Document 1, a cylindrical shaft configured to accommodate the speed reducer is connected to an outer peripheral portion of a carrier that is an output element of the speed reducer. A brake mechanism for applying braking torque is provided. Further, in the driving device described in Patent Document 2, the output shaft of the motor extends through the case that houses the motor and the speed reducer, and extends to the opposite side of the speed reducer. A brake mechanism for applying a braking torque to the portion is provided.

JP 2013-82321 A JP2013-82320A

  As described in Patent Document 1 and Patent Document 2, the drive device can be reduced in size by providing the drive device with a brake mechanism. In particular, since the required torque of the brake mechanism can be reduced by providing a brake mechanism on the input side of the speed reducer as in the drive device described in Patent Document 2, the brake mechanism itself can be reduced in size. As a result, the drive device can be reduced in size. However, since a vehicle equipped with a so-called in-wheel motor is driven independently, each wheel needs to have a parking lock mechanism for each wheel in order to maintain a parking state. If the parking lock mechanism is separately provided in addition to the drive device, the entire device provided on the wheel may be increased in size.

  Further, since the brake mechanism described in Patent Document 1 and Patent Document 2 is configured to control the braking torque by hydraulic pressure, a hydraulic mechanism such as an oil passage that supplies hydraulic pressure to the brake mechanism is provided. Become. Therefore, by providing such a hydraulic mechanism, there is a possibility that the entire apparatus provided on the wheel is enlarged.

  When the entire apparatus provided on the wheel is increased in size as described above, the weight of the wheel increases accordingly, so-called unsprung load increases, and traveling stability and riding comfort may be deteriorated.

  The present invention has been conceived by paying attention to the technical problems as described above, and has an object of providing a drive device having a parking lock function and capable of reducing the size of the entire device. is there.

  In order to achieve the above-mentioned object, the present invention is provided in each wheel of a vehicle, and is connected to the wheel so that torque can be transmitted to the wheel in a driving device capable of applying driving torque and braking torque to each wheel. And a motor that rotates on the same axis as the rotation center axis of the wheel, and a speed reduction mechanism that is connected to the motor and the wheel and that increases torque of the motor and transmits torque to the wheel. A brake mechanism coupled to an input side of the speed reduction mechanism, and the brake mechanism causes a brake torque to act on the brake rotor by frictional contact with the brake rotor coupled to the speed reduction mechanism. A first electromagnetic actuator capable of controlling a contact pressure between the brake stator and the brake stator and the brake rotor And a second electromagnetic actuator capable of maintaining a state in which the brake stator and the brake rotor are brought into contact with each other with a predetermined contact pressure even when the power of the vehicle is stopped. It is a feature.

  According to this invention, since the brake mechanism is connected to the input side of the speed reduction mechanism, the required torque of the brake mechanism can be reduced, and as a result, the brake mechanism can be reduced in size. The brake mechanism includes a brake rotor, a brake stator that generates a braking torque by frictional contact with the brake rotor, a first electromagnetic actuator that can control a contact pressure between the brake rotor and the brake stator, a brake stator, The second electromagnetic actuator is capable of maintaining a state in which the brake rotor is brought into contact with a predetermined contact pressure. Therefore, it is not necessary to separately provide a mechanism for parking lock, and it is not necessary to separately provide a hydraulic mechanism or the like, and the drive device can be reduced in size. As a result, the unsprung load can be reduced.

It is sectional drawing for demonstrating an example of the drive device in embodiment of this invention.

  FIG. 1 schematically shows a cross-sectional view for explaining an example of a drive device according to an embodiment of the present invention. A drive device 1 shown in FIG. 1 is mounted on any wheel of a vehicle, and a motor 2 is provided as a drive force source. The motor 2 can be configured in the same manner as a motor provided as a driving force source for a conventionally known hybrid vehicle or electric vehicle. As an example, the motor 2 can be configured by a three-phase synchronous motor. Specifically, it is constituted by an annular stator 4 fixed to the case 3 and a rotor 5 provided rotatably inside the stator 4. And the output shaft 6 is connected with the rotor 5 so that integral rotation is possible. The stator 4 is provided with a coil (not shown).

  The output shaft 6 extends to both sides of the rotor 5, and the extended portions are rotatably held by the case 3. A single pinion type planetary gear mechanism 7 is connected to an end portion extending outward in the vehicle width direction. The planetary gear mechanism 7 corresponds to the “deceleration mechanism” in the embodiment of the present invention. The sun gear 8 is connected to the output shaft 6 of the motor 2, and the ring gear 9 is integrated with the case 3. The torque of the motor 2 is amplified and output from a carrier 11 that holds the pinion gear 10 that meshes with the sun gear 8 and the ring gear 9 so as to be able to rotate and revolve around the rotation center of the sun gear 8. Has been. The carrier 11 is integrally formed with a cylindrical shaft 12 that opens to the outside in the vehicle width direction. That is, the cylindrical shaft 12 is provided so as to rotate about the same axis (rotation center axis) L2 as the rotation center axis L1 of the motor 2. The cylindrical shaft 12 is rotatably held by the case 3.

  An output member 13 extending outward in the vehicle width direction is connected to the cylindrical shaft 12, and a tire wheel 14 is fixed to the output member 13 with bolts 15. The tire wheel 14 includes a cylindrical portion 17 that surrounds the outside of the case 3 and to which a tire 16 is attached, and an annular wall portion 18 that is formed so as to close an opening on one side of the cylindrical portion 17. Bolts are fixed so that the side surface of the wall portion 18 and the side surface of the output member 13 are in contact with each other. That is, the tire 16 is configured to rotate about the same axis L2 as the cylindrical shaft 12 and to rotate about the same axis as the rotation center axis L1 of the motor 2.

  Further, a friction brake 19 capable of applying a braking torque to the output shaft 6 of the motor 2 is provided. The friction brake 19 corresponds to the “brake mechanism” in the embodiment of the present invention, and is configured by an excitation-operating electromagnetic brake that operates by energizing an electromagnet to brake a predetermined rotating member. Yes. In the example shown in FIG. 1, the friction brake 19 is fixed so as to rotate integrally with the output shaft 6 at an end portion of the output shaft 6 that extends to the opposite side to the end portion to which the planetary gear mechanism 7 is connected. A brake rotor 20 made of magnetic material, an annular brake stator 21 that can approach the brake rotor 20 and is spline-engaged with the case 3 in a non-rotatable manner, and a brake stator that generates electromagnetic force when energized 21 and a coil 22 attached to 21. The coil 22 corresponds to the “first electromagnetic actuator” in the embodiment of the present invention.

  Accordingly, when the coil 22 is energized, the friction brake 19 operates so as to frictionally engage the brake rotor 20 and the brake stator 21 by the electromagnetic force generated by the coil 22 and generates braking torque. The braking torque is transmitted to the tire 16 via the planetary gear mechanism 7.

  Further, when the coil 22 is de-energized, more specifically, even when the power of the vehicle is stopped, the brake rotor 20 and the brake stator 21 are brought into contact with each other with a predetermined contact pressure so that the output shaft 6 is moved. A parking brake (hereinafter referred to as EPB) 23 capable of maintaining a braked state is provided. In the example shown in FIG. 1, the EPB 23 includes a movable plate 24, a feed screw mechanism 25, and a braking motor 26 that operates the feed screw mechanism 25. The braking motor 26 corresponds to the “second electromagnetic actuator” in the embodiment of the present invention.

  The feed screw mechanism 25 is an actuating device that converts the rotational motion by the torque output from the braking motor 26 into a linear motion and presses the movable plate 24 toward the brake stator 21 side. The EPB 23 applies a torque in a predetermined rotation direction (normal rotation direction) to the feed screw mechanism 25 by the braking motor 26, thereby pressing the movable plate 24 and the brake stator 21 toward the brake rotor 20 side, thereby The rotor 20 and the brake stator 21 are frictionally engaged to brake the output shaft 6. On the contrary, the braking of the output shaft 6 by the EPB 23 can be released by applying a reverse torque to the feed screw mechanism 25 by the braking motor 26. That is, the brake rotor 20 has a function as one component of the EPB 23. The braking motor 26 is fixed to the case 3 so that the rotation center axis L3 of the braking motor 26 is coaxial with the rotation center axis L1 of the motor 2.

  In addition, the feed screw mechanism 25 in the EPB 23 is set such that the reverse efficiency of the feed screw when converting linear motion into rotational motion is lower than the positive efficiency of the feed screw when converting rotational motion into linear motion. Therefore, the state where the movable plate 24 and the brake stator 21 are pressed toward the brake rotor 20 by the feed screw mechanism 25 to brake the output shaft 6 can be maintained. Therefore, even if the energization of the coil 22 and the braking motor 26 is stopped while the feed screw mechanism 25 is operated by the braking motor 26 and the output shaft 6 is braked, the output shaft 6 by the EPB 23 is stopped. The braking state can be maintained. Therefore, the feed screw mechanism 25 in the EPB 23 generates a thrust for braking the output shaft 6 by converting the rotational motion into a linear motion, and maintains a state where the output shaft 6 is braked by generating a thrust. This is a thrust generating mechanism capable of.

  The EPB 23 can control the magnitude of the braking torque acting on the output shaft 6 of the motor 2 by controlling the contact pressure between the brake rotor 20 and the brake stator 21 by the braking motor 26. That is, the EPB 23 can function as a backup for the friction brake 19.

  A case 3 that houses the motor 2, the planetary gear mechanism 7, the friction brake 19, or the EPB 23 is connected to a suspension mechanism 28 via a knuckle 27.

  The drive device 1 described above outputs torque from the motor 2 when an acceleration request is made based on an accelerator operation by the driver. The torque is increased according to the gear ratio of the planetary gear mechanism 7 and transmitted to the tire 16. Similarly, when a deceleration request based on a brake operation or the like by the driver is made, the coil 22 is energized to generate a braking torque by bringing the brake stator 21 into contact with the brake rotor 20, or the motor 2 is regeneratively controlled according to the situation. Thus, a braking torque is generated. The braking torque is increased according to the gear ratio of the planetary gear mechanism 7 and transmitted to the tire 16.

  Therefore, by providing the motor 2 and the friction brake 19 on the input side of the planetary gear mechanism 7 that functions as a speed reduction mechanism as described above, the torque that should be output by the motor 2 and the friction brake 19 can be reduced. That is, the outer diameters of the motor 2 and the friction brake 19 can be reduced. As a result, the mountability of the motor 2 and the friction brake 19 can be improved, and so-called unsprung load can be reduced.

  Further, when the parking range is selected by operating a shift lever or a switch (not shown), the brake motor 26 is driven to bring the brake stator 21 and the brake rotor 20 into contact with each other and the brake motor 26 is energized in that state. To stop. As described above, since the reverse efficiency of the feed screw mechanism 25 is set to be lower than the normal efficiency, the brake stator 21 and the brake rotor 20 are in contact with each other even when the power supply to the braking motor 26 is stopped. Is maintained, in other words, the state in which the braking torque is applied to the tire 16 is maintained.

  As described above, since the brake rotor 20 has a function as one component of the EPB 23, the EPB 23 can be downsized as compared with a case where a so-called parking lock mechanism is separately provided. Furthermore, since the required torque can be reduced similarly to the friction brake 19, the EPB 23 can be reduced in size. As a result, the mountability of the EPB 23 can be improved and the unsprung load can be reduced.

  Furthermore, the drive device 1 can be reduced in size by arranging the motor 2, the friction brake 19, and the planetary gear mechanism 7 on the same axis.

  Since the friction brake 19 and the EPB 23 have the coil 22 and the braking motor 26 as actuators, it is not necessary to provide a hydraulic mechanism or the like, and the drive device 1 can be downsized accordingly, and the unsprung load Can be reduced.

  The planetary gear mechanism 7 is not limited to a single-pinion type planetary gear mechanism, and may be a double-pinion type planetary gear mechanism. A plurality of planetary gear mechanisms are connected in series to increase the gear ratio stepwise. It may be configured to increase. Moreover, the drive apparatus 1 should just be provided in the wheel which functions as a drive wheel, and does not need to be provided in all the four wheels.

  DESCRIPTION OF SYMBOLS 1 ... Drive device, 2 ... Motor, 6 ... Output shaft, 7 ... Planetary gear mechanism, 14 ... Tire wheel, 16 ... Tire, 19 ... Friction brake, 20 ... Brake rotor, 21 ... Brake stator, 22 ... Coil, 23 ... Parking brake (EPB), 26 ... braking motor, L1, L2, L3 ... rotation center axis.

Claims (1)

In the drive device that can be applied to each wheel of the vehicle and can apply a drive torque and a braking torque to each wheel,
A motor connected to the wheel so as to transmit torque and rotating on the same axis as the rotation center axis of the wheel;
A speed reduction mechanism connected to the motor and the wheel, and increasing torque of the motor to transmit the torque to the wheel;
A brake mechanism connected to the input side of the speed reduction mechanism,
The brake mechanism includes a brake rotor coupled to the speed reduction mechanism, a brake stator that applies a braking torque to the brake rotor by frictional contact with the brake rotor, and a contact pressure between the brake stator and the brake rotor. A controllable first electromagnetic actuator and a second electromagnetic actuator capable of maintaining a state in which the brake stator and the brake rotor are brought into contact with each other with a predetermined contact pressure even when the vehicle power supply is stopped. The drive device characterized by the above-mentioned.

Images