JPH05332405A - Electric automobile reduction gear - Google Patents

Abstract

PURPOSE:To provide an electric automobile speed reducer having high efficiency, by which a large reduction ratio can be obtained while its diameter and axial direction size can be maintained small. CONSTITUTION:In an electric automobile speed reducer, a pair of planetary gear devices 22, 24 wherein a planetary gears P1, P2 are integrally formed are provided, and a carrier C is connected to an input shaft 30 by a clutch K-1, so that the reduction output is taken out from a first sun gear S1 by taking a second sun gear S2 fixed to a transmission case 34 as a reaction element. If the reduction output is taken out from the first sun gear S1 by providing a ring gear in a planetary gear device 22, connecting the ring gear to the input shaft 30 to rotate the carrier C freely, and taking the second sun gear S2 as a reaction element, the larger reduction ratio can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear for an electric vehicle, and more particularly to a reduction gear with high efficiency that can obtain a large reduction gear ratio while maintaining a small radial dimension and axial dimension.

[0002]

2. Description of the Related Art An electric vehicle of the type in which the output of an electric motor is transmitted to driving wheels via a speed reducer in order to obtain a large driving torque has been proposed. In some cases, a speed reducer is arranged concentrically with the axes of the electric motor and the differential gear in the direction, and the rotation of the electric motor is decelerated and transmitted to the differential gear. In such an electric vehicle, since the electric motor and the speed reducer are arranged concentrically in the width direction of the vehicle, a large battery is loaded as compared with the case where they are arranged in the front-rear direction of the vehicle. It is convenient to secure space for indoor use and indoor space. American Society of Automotive Engineers SAE910
An example is the electric vehicle described in P63-68 of 246 (conventional example 1) and the electric vehicle described in the 9th International Electric Vehicle Symposium (EVS88-P16) (conventional example 2). is there.

In the above-mentioned conventional example 1, as shown in FIG. 12, a speed reducer 1 composed of a single pinion type planetary gear device.
00, and a pair of drive shafts 104 are rotationally driven via a differential gear 102 constituted by a double pinion type planetary gear unit. The speed reducer 100 includes a sun gear S, a ring gear R, and a carrier C rotatably arranged around an axis O, and a planetary gear P rotatably arranged on the carrier C and meshed with the sun gear S and the ring gear R. Consists of and
The sun gear S is connected to the rotary shaft of the electric motor via the input shaft 106, the ring gear R is integrally fixed to the transmission case 108, and the carrier C is the differential device 10.
It is connected to the second ring gear. In the speed reducer 100 configured in this way, the gear ratio (=
Number of teeth Z _S / ring gear R of the sun gear S Z _R) and ρ
Then, the reduction ratio i (= rotational speed of the input shaft 106 / rotational speed of the carrier C) is expressed by the following equation (1).

[0004]

## EQU1 ## i = (1 + ρ) / ρ (1)

Further, the conventional example 2 has a speed reducer 1 having a pair of planetary gear units 110 and 112 as shown in FIG.
14, a pair of drive shafts 118 is rotationally driven via a differential gear 116 having a plurality of bevel gears. Planetary gear unit 110
Is composed of a sun gear S and a carrier C which are rotatably arranged around an axis O, and a planetary gear P1 which is rotatably arranged on the carrier C and meshed with the sun gear S. A planetary gear P2, which has a diameter smaller than that of the planetary gear P1, is integrally provided on the planetary gear P1, and is rotatably arranged on the carrier C, and is rotatably arranged around an axis O and meshed with the planetary gear P2. And a ring gear R. The sun gear S is connected to the rotary shaft of the electric motor via the input shaft 120, and the ring gear R is integrally fixed to the transmission case 122.
The carrier C is connected to the differential case 124 of the differential device 116. In the speed reducer 114 configured in this way, if the gear ratios of the planetary gear units 110 and 112 are ρ ₁ and ρ ₂ , respectively, the reduction ratio i (= rotational speed of the input shaft 120 / rotational speed of the carrier C) is It is expressed by the following equation (2). Although the ring gear of the planetary gear unit 110 and the sun gear of the planetary gear unit 112 do not exist, the number of teeth Z _{S of} the sun gear, the number of teeth Z _{R of the} ring gear, and the number of teeth Z _P of the planetary gear in the single pinion type planetary gear unit are: Since there is a relationship of Z _S + 2Z _P = Z _R , the gear ratios ρ ₁ and ρ ₂ are determined from this relationship, and in this case, ρ ₁ <ρ ₂ .

[0006]

[Number 2] _{i = (1-ρ 1 ·} ρ 2) / ρ 1 · (1-ρ 2) ··· (2)

[0007]

However, in such a conventional speed reducer, there is a problem that a reduction ratio i of a sufficient magnitude cannot always be obtained, and a small electric motor cannot obtain sufficient vehicle running performance. It was That is, FIG.
When the gear ratio ρ is set to about 0.5 in the reduction gear 100 of FIG. 3, the reduction ratio i is about 3 and when the ρ ₁ and ρ ₂ are set to about 0.5 in the reduction gear 114 of FIG. It is about 3. Here, if the gear ratios ρ and ρ ₁ , ρ ₂ are reduced, the reduction ratio i increases. For example, in the reduction gear 100 of FIG. 12, when the gear ratio ρ is about 0.2, the reduction ratio i is about 6, but Since the diameter of the sun gear S has a design limit, it is necessary to increase the diameter of the ring gear R in order to reduce the gear ratio ρ. However, when the diameter of the ring gear R is increased, the diameter of the speed reducer 100 is increased, so that the inclination angle θ (see FIG. 3) of the drive shaft becomes excessive in order to secure the minimum ground clearance.
Not suitable for vehicle mounting. Further, in order to obtain a large reduction ratio while keeping the diameter of the reduction gear small, it is possible to arrange another planetary gear device in the axial direction to configure the reduction gear, but in that case, the number of parts is large. As a result, the weight increases and the number of gear meshes increases, resulting in poor efficiency, resulting in a large energy loss and a short travel distance per charge. In addition, since the axial dimension becomes long, if the speed reducer is arranged along with the electric motor in the width direction of the vehicle, the distance to the drive wheels becomes short, the inclination angle θ of the drive shaft becomes excessive, and the vehicle cannot be mounted on the vehicle. It may be impossible.

The present invention has been made in view of the above circumstances. An object of the present invention is to reduce the speed and the efficiency of an electric vehicle while maintaining a small radial dimension and a small axial dimension while achieving a large reduction ratio. To provide a machine.

[0009]

A first aspect of the invention for achieving the above object is to dispose the electric motor and the differential gear concentrically with each other in the width direction of the vehicle so as to rotate the electric motor. (A) a first sun gear and a carrier that are rotatably arranged around the axis, and a rotatably arranged on the carrier, A first planetary gear device including a first planetary gear that is engaged with the first sun gear, and (b) a second sun gear that has a diameter different from that of the first sun gear and is rotatably arranged around the axis. A second planetary gear unit that is integrally provided on the first planetary gear, is rotatably disposed on the carrier, and includes a second planetary gear that is meshed with a second sun gear;
(C) Input means for connecting the carrier to the rotary shaft of the electric motor, (d) connecting means for connecting the second sun gear to a fixed member, and (e) the differential gear from the first sun gear. And an output means for outputting to the device.

[0010]

In such a speed reducer, the carrier connected to the rotary shaft of the electric motor by the input means is the input element,
The second sun gear connected to the position-fixed member by the connecting means functions as a reaction element, and the first sun gear that outputs to the differential device via the output means functions as an output element, respectively, and the first planetary gear and the second planetary gear are integrated. The rotation of the carrier is decelerated by the pair of first planetary gear unit and the second planetary gear unit that are configured as a unit and output from the first sun gear. In this case, the gear ratio of the first planetary gear device and the second planetary gear device (= number of teeth of sun gear / number of teeth of ring gear)
Where ρ ₁ and ρ ₂ respectively, the reduction ratio i (= rotational speed of carrier / rotational speed of first sun gear) is expressed by the following equation (3). Although neither the first planetary gear device nor the second planetary gear device is provided with a ring gear, as described above, the number of teeth Z _{S of} the sun gear, the number of teeth Z _{R of the} ring gear, and the planetary gear of the single pinion type planetary gear device are Since the number of teeth Z _P has a relationship of Z _S + 2Z _P = Z _R , the gear ratios ρ ₁ and ρ ₂ are determined from this relationship.

[0011]

[Equation 3] i = ρ ₁ · (1-ρ ₂ ) / (ρ ₁ −ρ ₂ ) ... (3)

Since the first planetary gear and the second planetary gear are integrally formed, the gear ratios ρ ₁ and ρ ₂ correspond to the diameters of the first sun gear and the second sun gear. Ρ ₁ ≠ ρ
₂ , the smaller the difference between them, the larger the reduction ratio i. For example, if ρ ₁ = 0.55, ρ ₂ = 0.515, the reduction ratio i≈7.62. Further, when ρ ₁ <ρ ₂ , that is, when the diameter of the second sun gear is larger than that of the first sun gear, the reduction ratio i is negative and the input and output rotation directions are opposite to each other, but Forward rotation can be achieved by reversing the rotation direction of the motor.

[0013]

As described above, according to the speed reducer for an electric vehicle of the first aspect of the present invention, the gear ratio of each planetary gear device can be increased without reducing the gear ratio, in other words, without increasing the diameter of the reducer. It is possible to obtain a reduction gear ratio, and a sufficient driving torque can be obtained even with a small electric motor, so that the vehicle running performance is improved. In particular, in the present invention, since neither of the pair of planetary gear devices includes a ring gear, it is possible to further reduce the diameter dimension of the reduction gear and to reduce the inclination angle of the drive shaft, which is advantageous in mounting on a vehicle. .. On the other hand, since the speed reducer is configured by the pair of first planetary gear device and second planetary gear device in which the planetary gears are integrally configured with each other, the axial dimension is substantially the same as that of the conventional device of FIG. Compared to the case where three or more planetary gear devices are arranged in the axial direction in order to obtain a large reduction ratio, the inclination angle of the drive shaft does not become excessively large even for an electric vehicle having a narrow width and a light weight. It becomes possible to dispose the speed reducer together with the electric motor in the width direction of the vehicle. Further, when the number of planetary gear devices is increased to obtain a large reduction ratio, the number of parts and the number of meshes increase, the weight increases, the efficiency deteriorates, and the traveling distance per charge decreases, but in the present invention, It does not cause such performance deterioration.

[0014]

A second aspect of the present invention for achieving the above object is to dispose the electric motor and the differential gear in a concentric manner with respect to the axis of the electric motor and the rotation of the electric motor in the width direction of the vehicle. (A) A first sun gear, a ring gear, and a carrier that are rotatably arranged around the axis, and a carrier that is rotatable on the carrier. And a first planetary gear unit including a first planetary gear meshed with a first sun gear and a ring gear, and (b) a diameter different from that of the first sun gear and rotatably arranged about the axis. A second planetary tooth composed of a second sun gear and a second planetary gear that is integrally provided on the first planetary gear, is rotatably disposed on the carrier, and is meshed with the second sun gear. A device, input means for connecting the rotary shaft of the electric motor and (c) the ring gear, (d)
It is characterized by having a connecting means for connecting the second sun gear to a position-fixed member, and (e) an output means for outputting from the first sun gear to the differential device.

[0015]

In such a speed reducer, the ring gear connected to the rotary shaft of the electric motor by the input means is the input element, and the second sun gear connected to the position-fixed member by the connecting means is the reaction force element and the output means. The first sun gears that output to the differential device via
The rotation of the ring gear is decelerated by the pair of the first planetary gear device and the second planetary gear device in which the planetary gear and the second planetary gear are integrally formed, and the rotation is output from the first sun gear. In this case, assuming that the gear ratios of the first planetary gear device and the second planetary gear device are ρ ₁ and ρ ₂ , respectively, the reduction ratio i (= rotational speed of the ring gear / rotational speed of the first sun gear) is given by the following equation (4) ).

[0016]

[Equation 4] i = ρ ₁ · (1−ρ ₁ · ρ ₂ ) / (ρ ₁ −ρ ₂ ) ... (4)

Since the first planetary gear and the second planetary gear are integrally formed, the gear ratios ρ ₁ and ρ ₂ correspond to the diameters of the first sun gear and the second sun gear, and the diameters of both gears. Ρ ₁ ≠ ρ
₂ , the smaller the difference between them, the larger the reduction ratio i. For example, when ρ ₁ = 0.55 and ρ ₂ = 0.515, the reduction ratio i≈11.26. Also, ρ ₁ <ρ ₂ ,
That is, when the diameter dimension of the second sun gear is larger than that of the first sun gear, the reduction ratio i is negative and the input and output rotation directions are opposite to each other, but the rotation directions of the electric motors are opposite. This allows forward drive.

[0018]

As described above, according to the speed reducer for an electric vehicle of the second aspect of the present invention, the gear ratio of each planetary gear device can be increased without reducing the gear ratio, in other words, without increasing the diameter of the reducer. It is possible to obtain a reduction gear ratio, and a sufficient driving torque can be obtained even with a small electric motor, so that the vehicle running performance is improved. In particular, the second aspect of the invention makes it possible to obtain a larger reduction ratio than the first aspect of the invention. On the other hand, since the speed reducer is configured by the pair of first planetary gear device and second planetary gear device in which the planetary gears are integrally configured with each other, the axial dimension is substantially the same as that of the conventional device of FIG. Compared to the case where three or more planetary gear devices are arranged in the axial direction in order to obtain a large reduction ratio, the inclination angle of the drive shaft does not become excessively large even for an electric vehicle having a narrow width and a light weight. It becomes possible to dispose the speed reducer together with the electric motor in the width direction of the vehicle. Further, when the number of planetary gear devices is increased to obtain a large reduction ratio, the number of parts and the number of meshes increase, the weight increases, the efficiency deteriorates, and the traveling distance per charge decreases, but in the present invention, It does not cause such performance deterioration.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 3, reference numeral 10 denotes an electric motor, which is rotationally driven in both forward and reverse directions to rotationally drive the drive wheels 18 via the speed reducer 12, the differential gear 14, and the pair of drive shafts 16. The electric motor 10 is rotationally driven by supplying drive power from a power source such as a battery via an inverter, and the inverter is driven by a motor control computer (not shown) to change the frequency or voltage of the drive power. Torque control is performed, and the battery is charged with electric power generated by the forced rotation of the electric motor 10. The speed reducer 12 includes the electric motor 10 in the width direction of the vehicle.
Are arranged between the differential gear 14 and the differential gear 14 concentrically with those axes, and reduce the rotation of the electric motor 10 at a predetermined reduction ratio and transmit the reduced rotation to the differential gear 14. The differential device 14 is configured to include a plurality of bevel gears. Further, the drive shaft 16 is configured to include a constant velocity joint, and in order to secure the minimum ground clearance h from the road surface 20, the axis O
Is inclined by an inclination angle θ.

The speed reducer 12 has a first planetary gear set 22 and a second planetary gear set 24 as shown in FIG.
And the first planetary gear device 22 includes a first sun gear S rotatably arranged around the axis O.
1 and a carrier C, and a first planetary gear P1 rotatably arranged on the carrier C and meshed with a first sun gear S1. The second planetary gear device 24 has a smaller diameter than the first sun gear S1. A second sun gear S2 rotatably arranged around the axis O and a first planetary gear P1 integrally provided rotatably on the carrier C and meshed with the second sun gear S2. 2 planetary gears P2. The first sun gear S1 is integrally connected to the differential case 28 of the differential device 14 via an output shaft 26 as an output means, and the carrier C is directly connected to the rotary shaft of the electric motor 10. It is adapted to be selectively connected to the input shaft 30 via a clutch K-1, and the sun gear S2
Is fixed to the transmission case 34 via a connecting member 32 as a connecting means.

The clutch K-1 is composed of a hydraulic friction engagement device that is engaged by a hydraulic actuator, such as a multi-plate clutch having a plurality of friction materials, and the clutch K-1 is engaged. Combined carrier C
Is coupled to the input shaft 30, the carrier C functions as an input element, the second sun gear S2 functions as a reaction force element, and the first sun gear S1 functions as an output element, and the pair of first planetary gear device 22 and second planetary gear set 22 The rotation of the carrier C is decelerated by the gear device 24 and output from the first sun gear S1. When the electric motor 10 is normally rotated in this state, the electric vehicle is driven forward, and when it is rotated reversely, it is driven backward. When the clutch K-1 is released, the power transmission is cut off and the neutral state is established. The clutch K-1
The input shaft 30 corresponds to an input means. Note that FIG. 1 is a skeleton diagram in which the lower half of the axis O is omitted. FIG. 2 is a nomographic chart of the speed reducer 12, in which δ ₁ = (first sun gear S1
Number of teeth / number of teeth of the first planetary gear P1), and δ ₂
= (Number of teeth of the second sun gear S2 / second planetary gear P2
It is the number of teeth.

Here, the first planetary gear device 22 and the second planetary gear device 22
Assuming that the gear ratio of the planetary gear device 24 (= the number of teeth of the sun gear / the number of teeth of the ring gear) is ρ ₁ and ρ ₂ , respectively, the reduction ratio i (= the rotation speed Nin of the input shaft 30 during the power transmission)
/ The rotation speed Nout of the output shaft 26 is expressed by the above equation (3). For example, when ρ ₁ = 0.55 and ρ ₂ = 0.515, the reduction ratio i≈7.62. The above gear ratios ρ ₁ and ρ ₂
Has a relation of ρ ₁ > ρ ₂ because the second sun gear S2 has a smaller diameter than the first sun gear S1 and the planetary gears P1 and P2 are integrally rotated, and as is clear from the equation (3), The smaller the difference (ρ ₁ −ρ ₂ ) is, the larger the reduction ratio i is. Although neither the first planetary gear device 22 nor the second planetary gear device 24 is provided with a ring gear, the number of teeth of the sun gear Z _S , the number of teeth of the ring gear Z _R , the number of teeth of the planetary gear in the single pinion type planetary gear device are not provided. Since Z _P has a relationship of Z _S + 2Z _P = Z _R , the gear ratios ρ ₁ and ρ ₂ are determined from this relationship.

As described above, according to the speed reducer 12 of this embodiment, the gear ratios ρ ₁ and ρ ₂ of the planetary gear units 22 and 24 are not reduced, in other words, the diameter dimension of the speed reducer 12 is increased. It is possible to obtain a large reduction ratio without
Sufficient drive torque can be obtained even with the small electric motor 10, and the vehicle running performance is improved. In particular, in the present embodiment, since the pair of planetary gear units 22 and 24 are not provided with a ring gear, it is possible to further reduce the diameter dimension of the speed reducer 12 and to reduce the inclination angle θ of the drive shaft 16. It is advantageous in mounting on a vehicle.

On the other hand, since the speed reducer 12 is constituted by the pair of first planetary gear device 22 and second planetary gear device 24 in which the planetary gears P1 and P2 are integrally formed with each other, the axial dimension is as shown in FIG. Compared to the case where three or more planetary gear devices are arranged in the axial direction in order to obtain a large reduction gear ratio, the drive shaft is used even for an electric vehicle having a narrow width and a light weight, which is approximately the same as the conventional device. It is possible to dispose the speed reducer 12 together with the electric motor 10 in the width direction of the vehicle without the inclination angle θ of 16 becoming excessive. Further, if the number of planetary gear devices is increased to obtain a large reduction ratio, the number of parts and the number of meshes increase, the weight increases, the efficiency deteriorates, and the traveling distance per charge decreases, but this embodiment Then, such a performance deterioration is not caused.

The speed reducer 12 constitutes one embodiment of the first invention, but another embodiment of the invention will be described below. The following speed reducers shown in FIGS. 4 to 6 are embodiments of the first invention, and the speed reducers of FIGS. 7 to 11 are embodiments of the second invention. In each of the following embodiments, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The speed reducer 40 shown in FIG. 4 has a structure in which the clutch K-1 is eliminated and the carrier C is integrally connected to the input shaft 30 as compared with the speed reducer 12 of the first embodiment. Is set to zero by setting the output of the electric motor 10 to
Neutral and parking are possible.

The speed reducer 42 of FIG. 5 is different from the speed reducer 12 of the first embodiment in that the second sun gear S2 is connected to the transmission case 34 by the brake B, and the brake B and the clutch K are used. The vehicle is driven by engaging -1 and the brake B
By releasing at least one of the clutch K-1 and the clutch K-1, the neutral state is established. The brake B corresponds to connecting means and is composed of a hydraulic friction engagement device such as a multi-plate type or band type.

The speed reducer 44 shown in FIG. 6 corresponds to the speed reducer 4 shown in FIG.
The clutch K-1 is abolished as compared with 2, and the carrier C is integrally connected to the input shaft 30. In this case, by engaging the brake B, the vehicle is driven and the brake B is released. When released, it becomes neutral. The speed reduction ratios i of the speed reducers 40, 42, and 44 of FIGS. 4 to 6 are the same as those of the speed reducer 12 of the first embodiment, and are represented by the formula (3).

Compared with the speed reducer 12 of the first embodiment, the speed reducer 50 of FIG. 7 is arranged so as to be rotatable about the axis O and also has a ring gear R meshed with the first planetary gear P1. Using the first planetary gear device 52 having the above, the ring gear R is connected to the input shaft 30 by the clutch K-2, and the carrier C is rotatable. The clutch K-2 is the clutch K-1.
Similarly, when the clutch K-2 is engaged and the ring gear R is connected to the input shaft 30, the ring gear R is an input element,
The second sun gear S2 functions as a reaction force element and the first sun gear S1 functions as an output element, and the pair of first planetary gear devices 5
The rotation of the ring gear R is decelerated by the second and second planetary gear devices 24 and output from the first sun gear S1. When the electric motor 10 is normally rotated in this state, the electric vehicle is driven forward, and when it is rotated reversely, it is driven backward.
When the clutch K-2 is released, the power transmission is cut off and the neutral state is established. The clutch K-2 and the input shaft 30 correspond to input means. Note that FIG. 7 is a skeleton diagram in which the lower half of the axis O is omitted, and FIG. 8 is a collinear diagram of the speed reducer 50.

Here, the speed reduction ratio i of the speed reducer 50 is
When the gear ratio of the first planetary gear device 52 is ρ ₁ and the gear ratio of the second planetary gear device 24 is ρ ₂ , it is represented by the above formula (4),
For example, if ρ ₁ = 0.55, ρ ₂ = 0.515, the reduction ratio i≈11.26. The gear ratios ρ ₁ and ρ ₂ have a relationship of ρ ₁ > ρ ₂ because the second sun gear S2 has a smaller diameter than the first sun gear S1 and the planetary gears P1 and P2 are integrally rotated. As is clear from the above, the smaller the difference (ρ ₁ −ρ ₂ ) between them, the larger the reduction ratio i.

In the speed reducer 50 thus constructed,
Compared with the speed reducer 12 of the first embodiment, the diameter size is increased by the amount of the ring gear R, but the speed reducer 1
A reduction ratio i larger than 2 can be obtained, and if the electric motor 10 is the same, the driving torque is large and the vehicle traveling performance is improved. Can be promoted.

The speed reducer 54 shown in FIG. 9 corresponds to the speed reducer 5 shown in FIG.
Compared to 0, the clutch K-2 is abolished and the ring gear R is integrally connected to the input shaft 30. In this case, the output of the electric motor 10 is set to zero, thereby neutralizing, parking, etc. Is possible.

The speed reducer 56 of FIG. 10 is different from the speed reducer 50 of FIG. 7 in that the second sun gear S2 is connected to the transmission case 34 by the brake B, and the brake B and the clutch K-2 are used. Is brought into the vehicle drive state, and by releasing at least one of the brake B and the clutch K-2, the vehicle is brought into the neutral state. The brake B corresponds to the connecting means.

Compared to the speed reducer 56 of FIG. 10, the speed reducer 58 of FIG. 11 does not have the clutch K-2, and the ring gear R is integrally connected to the input shaft 30. In this case, , The vehicle is driven by engaging the brake B, and the neutral state is achieved by releasing the brake B. The speed reducers 54, 56 of FIGS.
The reduction gear ratios i of 58 are all the reduction gears 5 of the embodiment of FIG.
It is the same as 0 and is represented by the above formula (4).

Although some embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be carried out in still another mode.

For example, in the above embodiment, the first sun gear S1
The second sun gear S2 has a smaller diameter, and the gear ratio ρ ₁ = 0.
Although the reduction ratio i in the case of 55, ρ ₂ = 0.515 was calculated as an example, the gear ratios ρ ₁ , ρ ₂ can be set as appropriate in consideration of the required diameter dimension and the required reduction ratio. It is possible to make the diameter of the second sun gear S2 larger than that of the first sun gear S1, but in that case, ρ ₁ <ρ ₂ and the reduction ratio i becomes negative. The forward drive is performed when the electric motor 10 reversely rotates.

Further, although the differential device 14 of the above-mentioned embodiment has a plurality of bevel gears, it is also possible to employ another differential device such as a planetary gear device.

Further, although the input shaft 30 is directly connected to the rotary shaft of the electric motor 10 in the above-mentioned embodiment, it can be connected or disconnected by a clutch, or the input shaft 30 is constructed integrally with the rotary shaft of the electric motor 10. It is also possible to do.

Since the speed reducer of the present invention has a short axial dimension, it can be preferably used in a front-wheel drive vehicle.

Although not illustrated one by one, the present invention can be carried out in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a skeleton diagram of a speed reducer for an electric vehicle that is an embodiment of the first invention.

2 is a collinear diagram of the speed reducer of FIG. 1. FIG.

FIG. 3 is a diagram showing a state in which the speed reducer of FIG. 1 is arranged concentrically with an electric motor in a width direction of an electric vehicle.

FIG. 4 is a skeleton view of a speed reducer according to another embodiment of the first invention.

FIG. 5 is a skeleton view of a speed reducer according to still another embodiment of the first invention.

FIG. 6 is a skeleton view of a speed reducer according to still another embodiment of the first invention.

FIG. 7 is a skeleton diagram of a speed reducer that is an embodiment of the second invention.

8 is an alignment chart of the speed reducer of FIG. 7. FIG.

FIG. 9 is a skeleton view of a speed reducer according to another embodiment of the second invention.

FIG. 10 is a skeleton view of a speed reducer according to still another embodiment of the second invention.

FIG. 11 is a skeleton view of a speed reducer according to still another embodiment of the second invention.

FIG. 12 is a skeleton diagram showing an example of a conventional speed reducer.

FIG. 13 is a skeleton diagram showing another example of a conventional speed reducer.

[Explanation of symbols]

 10: Electric Motor 12, 40, 42, 44: Reduction Gear (First Invention) 14: Differential Device 22: First Planetary Gear Device 24: Second Planetary Gear Device 26: Output Shaft (Output Means) 30: Input Shaft (Input means) 32: Connection member (connection means) 50, 54, 56, 58: Reduction gear (2nd invention) 52: 1st planetary gear device K-1, K-2: Clutch (input means) B: Brake (Connecting means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kinya Yoshii, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor, Eiji Ichioka, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation

Claims (2)

[Claims] 1. A speed reducer for an electric vehicle, which is arranged concentrically with the shaft center of an electric motor and a differential device in the width direction of a vehicle and decelerates the rotation of the electric motor to transmit to the differential device. A first planetary gear device including a first sun gear and a carrier rotatably arranged around the axis, and a first planetary gear rotatably arranged on the carrier and meshed with the first sun gear. A second sun gear having a diameter different from that of the first sun gear and rotatably disposed about the axis; and a second sun gear integrally provided on the first planetary gear and rotatably disposed on the carrier. A second planetary gear device including a second planetary gear that meshes with two sun gears, an input unit that connects the carrier and a rotary shaft of the electric motor, and a portion that fixes the second sun gear in position. A speed reducer for an electric vehicle, comprising: connecting means for connecting to a material; and output means for outputting from the first sun gear to the differential device. 2. A speed reducer for an electric vehicle, which is arranged concentrically with an axis of an electric motor and a differential gear in the width direction of a vehicle, and reduces the rotation of the electric motor and transmits the rotation to the differential gear. A first sun gear rotatably arranged around the axis,
A first planetary gear device including a ring gear, a carrier, and a first planetary gear rotatably disposed on the carrier and meshed with the first sun gear and the ring gear; and the shaft center having a diameter different from that of the first sun gear. A second sun gear rotatably arranged around the second planetary gear and a second planetary gear integrally provided on the first planetary gear and rotatably disposed on the carrier and meshed with the second sun gear. A second planetary gear unit, an input unit connecting the ring gear and a rotating shaft of the electric motor, a connecting unit connecting the second sun gear to a fixed member, and the first sun gear to the differential unit. A reduction gear for an electric vehicle, comprising: an output unit for outputting.