WO2007097086A1

WO2007097086A1 - Electric car drive unit

Info

Publication number: WO2007097086A1
Application number: PCT/JP2006/323794
Authority: WO
Inventors: Tomoaki Makino
Original assignee: Ntn Corporation
Priority date: 2006-02-22
Filing date: 2006-11-29
Publication date: 2007-08-30
Also published as: JP2007224979A

Abstract

An electric car drive unit (20) comprises a first drive device (20a) having a motor part (21) for rotatingly driving a motor side rotation member (30) disposed in a casing and a reduction gear part (31) for reducing the rotational speed of the motor side rotation member (30) and transmitting the reduced rotational speed to a wheel side rotation member (38), and a second drive device (20b) of the same shape as the first drive device. Each of the reduction gear parts (31) of the first drive device (20a) and the second drive device (20b) includes a reduction gear part input shaft (32) having eccentric parts (32a, 32b), curved plates (33, 34) as revolving members rotatively held by the eccentric parts (32a, 32b), a plurality of outer pins (35) as outer peripheral engagement members engaged with the outer peripheral parts of the curved plates (33, 34), and a motion converting mechanism for transmitting the rotating motions of the curved plates (33, 34) to the wheel side rotating member (38).

Description

Specification

Electric vehicle drive unit

Technical field

[0001] The present invention relates to an electric vehicle drive unit that rotationally drives drive wheels of an electric vehicle or the like.

Background art

[0002] A conventional electric vehicle drive unit is described in, for example, Japanese Patent Application Laid-Open No. 2005-7914. The electric vehicle drive unit described in the publication discloses a motor that generates a driving force, a wheel hub that connects the tire, and the motor and the wheel hub to reduce the rotation of the rotor of the motor to the tire. A transmission reduction gear. This speed reducer employs a parallel shaft gear mechanism formed by combining a plurality of gears having different numbers of teeth.

[0003] The electric vehicle drive unit in which the output shaft of the electric motor and the wheel hub are coaxially connected via a speed reducer does not require a large power transmission mechanism such as a propeller shaft or a differential gear. Therefore, it is attracting attention in terms of reducing the weight and size of vehicles. However, the electric vehicle drive unit attached to the unsprung part of the vehicle has a problem that the riding comfort becomes worse due to the increase of the unsprung weight, and has not yet been put into practical use.

[0004] The output torque of the electric motor and the motor volume (weight) are approximately proportional, and in order to obtain a large output sufficient to drive the wheels of a vehicle with a small motor volume, high-speed rotation cannot be avoided. It is necessary to incorporate a reduction gear between the output shaft of the electric motor and the hub. For this reason, it is meaningless if the weight of the built-in speed reducer is large. Therefore, a compact speed reducer capable of obtaining a large speed reduction ratio is required for an electric vehicle drive unit.

[0005] Further, as a reduction device for an electric vehicle, there is one in which a planetary gear reduction device is incorporated as a reduction device between an output shaft of an electric motor and a wheel hub (see, for example, JP-A-5-332401). ). The one described in JP-A-5-332401 is not an electric vehicle drive unit in which the electric motor and the speed reducer are mounted under the spring, but the planetary gear speed reducer is provided in two stages, and the second stage planetary gear speed reduction is provided. The output from the machine is distributed to the left and right unsprung wheels via the drive shaft. [0006] The reduction ratio of the parallel shaft gear mechanism and the planetary gear mechanism employed in the reduction gears described in each of the above publications is the former force SlZ2 to lZ3 from the viewpoint of gear strength and the like, and the latter is 1Z3 to 1 Generally set to about Z6. This is insufficient as a reduction ratio of a reduction gear mounted on an electric vehicle drive unit. In order to obtain a sufficient reduction ratio, the reduction gear needs to have a multistage configuration. This leads to an increase in the weight and size of the reducer, which is inappropriate for electric vehicle drive units that require a connecting toy.

[0007] Further, the planetary gear reducer described in JP-A-5-332401 can obtain a large reduction ratio as compared with a parallel shaft gear. Since it is composed of a pinion gear carrier, there is a problem that the number of parts is large and compaction is difficult.

Disclosure of the invention

[0008] Therefore, an object of the present invention is to provide an electric vehicle drive unit that employs a speed reduction unit that is compact and provides a high speed reduction ratio.

[0009] An electric vehicle drive unit according to the present invention includes first and second drive devices that respectively rotate and drive left and right wheels. Each drive device includes a motor unit that rotationally drives the motor-side rotation member, and a reduction unit that decelerates the rotation of the motor-side rotation member and transmits it to the wheel-side rotation member fixedly connected to the wheel knob. The motor-side rotating member includes an eccentric portion, and the speed reducing portion is rotatably held by the eccentric portion, and performs a revolving motion centering on the rotation axis as the motor-side rotating member rotates. The outer peripheral engagement member that engages with the outer peripheral portion of the revolution member and causes the rotation of the revolution member, and the rotation movement of the revolution member is converted into a rotation movement around the rotation axis of the motor side rotation member. And a movement mechanism that transmits to the wheel side rotating member. Furthermore, the motor-side rotating member of the first driving device and the motor-side rotating member of the second driving device are arranged coaxially. In addition, the revolution member has, for example, a plurality of waveforms on the outer peripheral portion thereof.

[0010] Preferably, the counter member further includes a counterweight attached to the motor-side rotating member in a phase that cancels the unbalanced inertial couple due to the eccentric motion of the revolving member. In the case of having a plurality of revolving members, the eccentric portion generates an unbalanced inertia couple together with the centrifugal force. Therefore, the counterweight is arranged at a phase that cancels out the unbalanced inertial couple generated by the revolving member. Thus, the vibration of the electric vehicle drive device (of the present invention) can be suppressed.

[0011] The motion mechanism has, for example, an inner pin that connects the revolving member and the wheel-side rotating member, and a hole that receives an inner pin whose diameter is larger than the outer diameter of the inner pin by a predetermined amount. For example, the hole is provided in the revolving member, and the inner pin is held by the wheel side rotating member. By adopting the motion modification having the above-described configuration, the rotational motion of the revolution member can be transmitted to the wheel-side rotation member.

[0012] Preferably, the motor-side rotation member includes a cylindrical motor rotation shaft that is rotationally driven by the motor, and a speed reducer input shaft having an outer diameter surface that fits into the inner diameter surface of the motor rotation shaft. The motor rotation shaft and the speed reduction unit input shaft are spline-fitted.

[0013] By configuring the motor side rotation member with the motor rotation shaft and the speed reduction unit input shaft as in the above configuration, the shape of each member can be simplified. Also, the assembly of the motor-side rotating member is improved by fitting both the members by spline fitting.

[0014] According to the present invention, it is possible to obtain an electric vehicle drive unit incorporating a speed reduction unit that is compact and can provide a large reduction ratio. Brief Description of Drawings

FIG. 1 is a diagram showing an electric vehicle drive unit according to an embodiment of the present invention.

2 is a diagram showing an electric vehicle employing the electric vehicle drive unit of FIG.

FIG. 3 is a diagram showing a first drive device of the electric vehicle drive unit of FIG. 1.

FIG. 4 is a partially enlarged view of the speed reducing portion of FIG.

FIG. 5 is a cross-sectional view taken along the line ZZ in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to FIG. 1 and FIG. 2, an electric vehicle drive unit 20 according to an embodiment of the present invention will be described.

Referring to FIG. 2, an electric vehicle 11 has a driving force applied to a chassis 12, front wheels 13a and 13b as steering wheels, rear wheels 14a and 14b as drive wheels, and left and right drive shafts 15a and 15b. Electric vehicle drive unit 20 for transmitting the power. In general, the drive shafts 15a and 15b are composed of constant velocity joints and shaft portions, and are spline-fitted to the vehicle drive unit 20 and the drive wheels 14a and 14b. Here, in order to expand the cabin space of the electric vehicle 11, the model shown in Fig. 1 is used. An electric vehicle drive unit 20 according to an embodiment of the present invention is employed.

Referring to FIG. 1, an electric vehicle drive unit 20 includes a motor unit 21 that rotationally drives a motor-side rotating member 30 disposed in a casing, and a wheel side that decelerates the rotation of the motor-side rotating member 30. The first drive device 20a having a speed reducing portion 31 that transmits to the rotating member 38, and the second drive device 20b having the same shape as the first drive device, the first drive device 20a drives the drive shaft 15a to the second drive The device 20b drives the drive shaft 15b to rotate. Further, the motor side rotating member 30 of the first drive device 20a and the motor side rotating member 30 of the second drive device 20b are arranged coaxially.

Next, the structure of the first drive device 20a will be described with reference to FIG. Note that the second driving device 20b has the same shape as the first driving device 20a, and thus the description thereof is omitted.

[0020] The motor 21 of the first drive device 20a includes a stator 24 fixed to the casing, a rotor 23 disposed with a gap in the radial direction inside the stator, and a rotor 23 fitted into the rotor 23. The radial gap motor includes a motor rotating shaft 22 that rotates integrally with the motor 23.

[0021] The speed reducer 31 includes a speed reducer input shaft 32 having eccentric parts 32a and 32b, and curved plates 33 and 3 4 as revolving members that are rotatably held by the eccentric parts 32a and 32b by rolling bearings 33a and 34a. And a plurality of outer pins 35 as outer peripheral engagement members that are held in a fixed position on the casing and engage with the outer peripheral portions of the curved plates 33 and 34, and the wheel side rotating member 38 And a counterweight 36a, 36b.

Here, the motor-side rotating member 30 includes a cylindrical motor rotating shaft 22 that is rotationally driven by the motor 21, and a speed reducing portion that has an outer diameter surface that fits into the inner diameter surface of the motor rotating shaft 22. It is configured by spline fitting the force shaft 32. The motor-side rotating member 30 is rotatably supported by rolling bearings 30a, 30b, and 30c at both ends of the motor 21 and the left end of the speed reduction portion 31.

[0023] As shown in FIG. 5, the curved plate 33 has a plurality of corrugations formed of a trochoidal system curve such as epitrochoid on the outer peripheral portion, and has a plurality of through holes penetrating the one end surface force and the other end surface. 3 3b are provided at equal intervals on a circumferential track centering on the rotation axis of the curved plate 33. The curved plate 34 has the same shape as the curved plate 33.

[0024] The outer pins 35 are equally spaced on a circumferential track around the rotation axis of the motor side rotating member 30. Is provided. This coincides with the revolution trajectory of the curved plates 33, 34. Therefore, when the curved plates 33, 34 revolve, the curved waveform and the outer pin 35 are engaged, and the curved plates 33, 34 rotate. Give rise to Further, in order to reduce the contact resistance with the curved plates 33, 34, needle roller bearings 35a are provided at positions where they contact the outer peripheral surfaces of the curved plates 33, 34.

[0025] The counterweights 36a and 36b are disc-shaped and have a through-hole that engages with the speed reduction unit input shaft 32 at a position where the central force is also removed, and are unbalanced inertia couples generated by the rotation of the curved plates 33 and 34. In order to cancel out, the eccentric portions 32a and 32b are arranged outside the eccentric portions 32a and 180 degrees out of phase.

[0026] Here, the curved plates 33, 34 and the counterweights 36a, 36b are, as shown in FIG. 4, the center point between the two curved plates 33, 34 is G, and the center point G and each curve The distance between the center of the plates 33 and 34 is Ll, the distance between the center point G and each counterweight 36a, 36b is L2, and the mass of the curved plate 33 and counterweight 36a on the left side of the center point G is ml, from the center point G. If the mass of the right curved plate 34 and the counterweight 36b is m2, and the eccentricity of the center of gravity of the center of gravity is ε 1 and ε 2, respectively, LI X mix ε l = L2 X m2 X ε Become a relationship that satisfies 2!

[0027] The motion structure is composed of a plurality of inner pins 37 held by the wheel-side rotating member 38 and through holes 33b, 34b provided in the curved plates 33, 34. The inner pins 37 are provided at equal intervals on a circumferential track centering on the rotation axis of the wheel side rotation member 38. Further, in order to reduce the contact resistance with the curved plates 33, 34, needle roller bearings 37a are provided at positions in contact with the inner wall surfaces of the through holes 33b, 34b of the curved plates 33, 34. On the other hand, the through holes 33b and 34b are provided at positions corresponding to the plurality of inner pins 37. The inner diameters of the through holes 33b and 34b are the outer diameters of the inner pins 37 (the maximum outer diameter including the needle roller bearing 37a). (Diameter) is set larger by a predetermined amount.

[0028] The wheel-side rotating member 38 has a flange portion having a hole for holding the inner pin 37 on the end surface, and a cylindrical shaft portion that is fitted to the drive shaft 15b. It is supported rotatably by rolling bearings 38a and 30c.

[0029] The operating principle of the first drive device 20a configured as described above will be described in detail.

[0030] For example, the motor 21 supplies an alternating current to the coil of the stator 24 by an external force. In response to the electromagnetic force generated, the rotor 23 constituted by a permanent magnet or a DC electromagnet rotates. At this time, the rotor 23 rotates at a higher speed as the voltage of higher frequency is applied to the coil.

Thus, when the motor side rotating member 30 connected to the rotor 23 rotates, the curved plates 33 and 34 revolve around the rotation axis of the motor side rotating member 30. At this time, the outer pin 35 engages with the curved waveform of the curved plates 33 and 34 to cause the curved plates 33 and 34 to rotate in the direction opposite to the rotation of the motor side rotating member 30.

[0032] The inner pin 37 passing through the through holes 33b and 34b comes into contact with the inner wall surface of the through holes 33b and 34b as the curved plates 33 and 34 rotate. It is transmitted to the drive shaft 15a via the wheel side rotating member 38. From this, the revolving motion of the curved plates 33 and 34 is not transmitted to the inner pin 37, but only the rotational motion of the curved plates 33 and 34 is transmitted to the wheel side rotating member 38.

[0033] It should be noted that the speed reduction ratio of the speed reduction unit 31 having the above-described configuration is such that the number of outer pins 35 is Z and the wave of the curved plates 33 and 34 is

A

If the number of shapes is Z, it is calculated as (Z — Z) / Z. In the embodiment shown in FIG. 5, Z =

B A B B A

12, Z = 11

Since it is B, the reduction ratio is と ι, and a very large reduction ratio can be obtained compared to parallel shaft gear reducers and planetary gear reducers.

[0034] Thus, by adopting the reduction gear 21 that can obtain a large reduction ratio without using a multistage configuration, a compact and high reduction ratio electric vehicle drive unit can be obtained. Further, by providing the needle roller bearings 35a, 37a at the positions where they contact the curved plates 33, 34 of the outer pin 35 and the inner pin 37, the contact resistance is reduced, so the transmission efficiency of the speed reduction part 31 is improved. I will go up.

The above description of the operation has been made by paying attention to the rotation of each member. Actually, however, power including torque is transmitted from the electric motor 21 to the rear wheels 14a, 14b. Therefore, the power reduced as described above is converted to high torque.

[0036] In the above description of the operation, power is supplied to the electric motor 21 to drive the electric motor 21, and the power transmitted from the electric motor 21 to the rear wheels 14a, 14b is the opposite of this. When the vehicle decelerates or goes down a hill, the power from the rear wheels 14a, 14b is converted into high-rotation low-torque rotation by the speed reduction mechanism 31 and transmitted to the electric motor 21. 21 may generate electricity. In addition, the power generated here is stored in a knotter and later The electric motor 21 may be driven or used for the operation of other electric devices provided in the vehicle.

[0037] In the electric vehicle drive unit 20 configured as described above, since the rotation of the motor 21 is decelerated by the speed reduction unit 31 and transmitted to the drive wheels 14a and 14b, the low-torque, high-rotation type motor 21 is used. However, it is possible to transmit the necessary torque to the drive wheels 14a and 14b. As a result, the electric vehicle drive unit 20 can be reduced in size and weight, so that the electric vehicle 11 having a large cabin space and low fuel consumption can be obtained.

[0038] In each of the above-described embodiments, the force provided with two curved plates of the speed reduction unit with a 180 ° phase change can be set arbitrarily. For example, three curved plates are provided. In this case, it is recommended to change the 120 ° phase.

[0039] In addition, although the motion conversion mechanism in the above-described embodiment has been illustrated as an example including the inner pin fixed to the wheel side rotation member and the through hole provided in the curved plate, the present invention is not limited thereto. The rotation of the speed reducer can be arbitrarily configured to be transmitted to the drive wheels. For example, it may be a motion conversion mechanism composed of an inner pin fixed to a curved plate and a hole formed in the wheel side rotating member.

[0040] Further, in each of the above embodiments, the example in which the bearings provided on the outer pin and the inner pin are needle roller bearings from the viewpoint of reducing the radial thickness is shown, but the present invention is not limited thereto. For example, cylindrical roller bearings, tapered roller bearings, angular contact ball bearings, four-point contact ball bearings, self-aligning roller bearings, etc. Can do. Similarly, any type of rolling bearing can be applied as a bearing that supports the motor-side rotating member, the wheel-side rotating member, the gear carrier, and the like.

[0041] Further, in each of the above-described embodiments, the force shown in the example using a radial gap motor in which a radial gap is provided between the stator and the rotor is applied. Any type of motor is not limited thereto. be able to. For example, by applying an axial gap motor in which an axial gap is provided between the stator and the rotor, the electric vehicle drive unit can be made compact in the axial direction.

[0042] In the electric vehicle 11 shown in Fig. 2, the rear wheels 14a and 14b are used as driving wheels. However, the front wheels 13a and 13b are not limited to this. It may be a car. In the present specification, the term “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and should be understood as including, for example, hybrid vehicles.

[0043] Further, the motor-side rotating member shown in each of the above embodiments can be simplified in shape by spline-fitting the motor rotating shaft and the speed reducing portion input shaft, and Assemblability is improved. However, an integrated motor-side rotating member that is not limited to this may be used.

[0044] The power of the embodiment of the present invention described above with reference to the drawings. The present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope or equivalent scope as the present invention.

Industrial applicability

[0045] The present invention is advantageously used in an electric vehicle drive unit employed in an electric vehicle or the like.

Claims

The scope of the claims

[1] The first and second drive devices for rotating the left and right wheels respectively are provided,

Each drive unit is

A motor unit for rotationally driving the motor side rotating member;

A speed reducer that decelerates the rotation of the motor side rotating member and transmits it to the wheel side rotating member fixedly connected to the wheel hub,

The motor side rotation member includes an eccentric part,

The deceleration part is

A revolving member that is rotatably held by the eccentric part and performs a revolving motion about its rotation axis as the motor side rotation member rotates;

An outer peripheral engaging member that engages with the outer peripheral part of the revolving member to cause the rotational movement of the revolving member;

A motion conversion mechanism that converts the rotational motion of the revolving member into a rotational motion centered on the rotational axis of the motor-side rotating member and transmits the rotational motion to the wheel-side rotating member, and the motor of the first drive device The electric vehicle drive unit, wherein the side rotation member and the motor side rotation member of the second drive device are arranged coaxially.

[2] The revolution member has a plurality of corrugations on its outer periphery,

The electric vehicle drive unit according to claim 1, wherein the outer peripheral engagement member has a plurality of outer pins arranged on a revolution track of the revolution member.

[3] The electric vehicle drive unit according to [1], further comprising a counterweight attached to the motor-side rotating member in a phase that cancels out an unbalanced inertia couple due to an eccentric motion of the revolving member.

[4] The motion conversion mechanism includes an inner pin that connects the revolution member and the wheel-side rotation member;

The electric vehicle drive unit according to claim 1, further comprising a hole for receiving the inner pin whose diameter is larger by a predetermined amount than the outer diameter of the inner pin.

[5] The motor-side rotation member includes a cylindrical motor rotation shaft that is rotationally driven by the motor, and a speed reducer input shaft having an outer diameter surface that fits into an inner diameter surface of the motor rotation shaft, The electric vehicle drive unit according to claim 1, wherein the motor rotation shaft and the speed reduction portion input shaft are spline-fitted.