JP7002391B2 - Electric drive unit for vehicles - Google Patents

Description

The present invention relates to an electric drive unit mounted on a vehicle whose drive source is an electric motor.

For example, an electric vehicle (EV vehicle) is provided with an electric drive unit, which transfers the rotation of the rotor shaft of the motor (motor / generator) to the left and right output shafts via a reduction mechanism and a differential device. It is to convey.

Such electric drive units include those using a planetary gear mechanism as a reduction mechanism (hereinafter referred to as "electric drive unit having a planetary structure"), and large and small counter shafts arranged parallel to the rotor shaft. There are those provided with a plurality of reduction gears having different diameters (hereinafter, referred to as "motor drive unit having a parallel shaft structure").

However, in the electric drive unit having a planetary structure, since the planetary gear mechanism and the differential device are arranged coaxially, there is a problem that the entire width is expanded and the electric drive unit becomes large.

Further, in the electric drive unit having a parallel axis structure, the overall width can be reduced as compared with the electric drive unit having a planetary structure, but either the overall length or the overall height becomes larger and the electric drive unit becomes larger. There is a problem.

By the way, Patent Documents 1 and 2 disclose a configuration in which a pair of counter shafts are arranged in parallel in a transmission device of a vehicle and a plurality of speed change gears are provided on each counter shaft (hereinafter, referred to as "twin counter structure"). ing.

Japanese Patent No. 2762274 Japanese Patent No. 3639933

However, Patent Documents 1 and 2 disclose a twin counter structure in a transmission of a vehicle, but do not disclose a configuration in which a twin counter structure is adopted in an electric drive unit including a differential device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle motor unit capable of extracting the merits of each of a planetary structure and a parallel axis structure and realizing miniaturization. It is in.

By the way, regarding the lubrication of the conventional electric drive unit for vehicles, the forced lubrication method in which the oil for lubrication is supplied to each part by an oil pump to lubricate each part, or the oil is collected at the bottom of the case accommodating the electric drive unit. A method is adopted in which oil is pumped up by the rotation of a gear to lubricate bearings and the like.

However, according to the forced lubrication method, an oil pump is required, and power for driving the oil pump is required. In addition, in the lubrication method in which the oil stored in the bottom of the case is lifted by a gear, the oil level in the case becomes high because it is necessary to store the oil in the amount required for lifting, and the oil by the gear. There is also a problem that the stirring resistance of the oil increases and the power loss increases.

Therefore, another object of the present invention is to provide an electric drive unit for a vehicle capable of reducing the number of parts and cost by omitting an oil pump and suppressing the power loss due to the stirring resistance of oil. be.

In order to achieve the above object, the present invention transmits the rotation of the rotor shaft (4) of the motor (3) to the left and right output shafts (10L, 10R) via the deceleration mechanism (T) and the differential device (D). An electric vehicle drive unit (1), wherein the deceleration mechanism (T) is attached to a pair of counter shafts (14) arranged in parallel with the rotor shaft (4) and each counter shaft (14). It is characterized in that it is configured to include a plurality of reduction gears (15, 16) of different sizes provided respectively.

According to the electric drive unit for a vehicle according to the present invention, since the twin counter structure in which a pair of counter shafts are arranged in the deceleration mechanism is adopted, the advantages of the planetary structure and the parallel shaft structure are extracted and the width dimension and the height are extracted. The dimensions can be reduced, and as a result, the size of the electric drive unit for the vehicle can be reduced.

Here, the reduction mechanism (T) includes a pinion gear (8) provided on the rotor shaft (4) and meshes with the reduction gear (15) on the large diameter side of the reduction gears (15, 16) and the differential. The device (D) is provided with a ring gear (20) provided in the differential case (19) and meshes with the reduction gear (16) on the small diameter side of the reduction gears (15, 16).

Further, in the present invention, the differential device (D) is arranged coaxially with the rotor shaft (4) and between the pair of counter shafts (14). According to this, the differential device can be housed compactly.

Further, in the present invention, the pair of counter shafts (14) are arranged diagonally with respect to the horizontal plane so that each axis is located on an oblique plane passing through the axis of the rotor shaft (4), and downward. An oil tank (27) may be placed above one of the counter shafts (14) located.

Further, in the present invention, the oil introduction port (27a) for introducing the oil scooped up by the reduction gear (15) on the large diameter side of the reduction gear (15, 16) onto the side surface of the oil tank (27). May be formed, and an oil discharge port (27b) for discharging the oil stored in the oil tank (27) may be formed on the bottom surface of the oil tank (27).

Therefore, according to the present invention, the oil tank is arranged in the space formed above the counter shaft located below, and the oil pumped up by the reduction gear on the large diameter side provided on the lower counter shaft is pumped up by the oil tank. The oil stored in the oil tank can be dropped onto a bearing that rotatably supports the counter shaft to lubricate the bearing. Therefore, an oil pump for forced lubrication becomes unnecessary, and the number of parts can be reduced and the cost can be reduced. Since a part of the oil required for lubrication can be stored in the oil tank, for example, the amount of oil stored in the bottom of the housing can be small. As a result, the height of the oil level of the oil can be kept low, and the power loss due to the stirring resistance of the oil by the reduction gear can be kept small.

According to the present invention, it is possible to extract the merits of each of the planetary structure and the parallel axis structure and realize the miniaturization of the electric drive unit for a vehicle. In addition, the oil pump can be omitted to reduce the number of parts and costs, and the power loss due to the agitation resistance of the oil can be suppressed to a small value.

It is sectional drawing of the electric drive unit for vehicles which concerns on this invention (the sectional view taken along line BB of FIG. 2). It is a figure which looked at the inside of the gear case of the electric drive unit for a vehicle which concerns on this invention from the inside (arrow view of line AA of FIG. 1). It is a perspective view of the electric drive unit for a vehicle which concerns on this invention as seen from the anti-motor side. It is a perspective perspective view which saw the electric drive unit for a vehicle which concerns on this invention from an oblique side.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of the electric drive unit for a vehicle according to the present invention (cross-sectional view taken along the line BB in FIG. 2), and FIG. 2 is a view of the inside of the gear case of the electric drive unit for the vehicle from the inside (A in FIG. 1). -Line A arrow view), FIG. 3 is a perspective perspective view of the electric drive unit for the vehicle from the anti-motor side, and FIG. 4 is a perspective perspective view of the electric drive unit for the vehicle from the diagonal side. be.

The vehicle electric drive unit 1 according to the present invention is mounted on an electric vehicle (EV vehicle) (not shown), and as shown in FIG. 1, has a bottomed tubular motor case 2A and a gear case 2B. A motor case 2A, which is a drive source, is housed in a motor case 2A of an integrated housing 2, and a reduction mechanism T and a differential device (differential device) D are housed in a gear case 2B. There is.

In the present embodiment, the electric motor 3 is composed of a three-phase brushless motor, and is a hollow rotor 3a rotatably housed in the motor case 2A and a motor case 2A arranged around the rotor 3a. It is provided with a ring-shaped stator 3b fixed to the inner circumference of the above. Here, the rotor 3a contains a plurality of permanent magnets (not shown), and the stator 3b is wound with coils 3b1 for three phases. Then, as shown in FIG. 1, a cylindrical rotor shaft 4 long in the vehicle width direction (left-right direction in FIG. 1) is inserted and fixed to the shaft center of the rotor 3a of the motor 3, and the rotor shaft 4 is fixed. , Rotates integrally with the rotor 3a. Here, one end in the longitudinal direction (left end in FIG. 1) of the rotor shaft 4 is rotatably supported by the motor case 2A by a bearing (ball bearing) 5, and the other end in the longitudinal direction (right end in FIG. 1) is a ring. It is rotatably supported by the motor case 2A by a bearing (ball bearing) 7 held in the shaped holder 6. A pinion gear 8 having a small diameter is integrally formed at an axial end portion (right end portion in FIG. 1) facing the inside of the gear case 2B of the rotor shaft 4. The holder 6 is attached to the motor case 2A by a plurality of bolts (only one is shown in FIG. 1) 9.

Inside the rotor shaft 4, one (left side) output shaft 10L of the left and right output shafts 10L and 10R coaxially arranged in the vehicle width direction is inserted coaxially and rotatably. One end in the axial direction (left end in FIG. 1) of 10 L is rotatably supported by the motor case 2A by a bearing (ball bearing) 11. An axle (not shown) is connected to the end of the portion of the output shaft 10L extending to the outside of the motor case 2A via a coupling 12, and the gear case 2B of the output shaft 10R on the other side (right side) is connected. An axle (not shown) is connected to the end of the portion extending outward via a coupling 13. A drive wheel (not shown) is attached to each end of the left and right axles.

The reduction mechanism T has a pair of counter shafts 14 arranged in parallel to the rotor shaft 4 and the left and right output shafts 10L and 10R in the gear case 2B, and large and small different diameters integrally formed with the counter shafts 14. A twin counter structure is configured including reduction gears 15 and 16. Here, each counter shaft 14 is rotatably supported by the motor case 2A by a bearing (ball bearing) 17 having one end in the axial direction (left end in FIG. 1) held in the holder 6, and the other end in the axial direction (FIG. 1). The right end of 1) is rotatably supported by the gear case 2B by a bearing (needle bearing) 18.

The reduction gear 15 on the large diameter side is integrally formed in the portion of each hollow counter shaft 14 close to the bearing (boli bearing) 17, and the reduction gear 15 on the large diameter side is integrally formed in the portion close to the bearing (needle bearing) 18 on the small diameter side. The reduction gears 16 are integrally formed. The large-diameter gear 15 formed on each counter shaft 14 meshes with the pinion gear 8 formed at the end of the rotor shaft 4, and these pinion gears 8 and the large-diameter reduction gear 15 are engaged with each other. Consists of the first-stage reduction gear train. Further, the reduction gear 16 on the small diameter side formed on each counter shaft 14 meshes with the large diameter ring gear 20 attached to the rotatable differential case 19 of the differential device D, and the reduction gear 16 on the small diameter side thereof. And the ring gear 20 constitute a second-stage reduction gear train. In the present embodiment, the pinion gear 8 formed on the rotor shaft 4 and the reduction gear 15 on the large diameter side of each counter shaft 14 meshing with the pinion gear 8 are composed of spur gears, and the small diameter of each counter shaft 14 is small. The reduction gear 16 on the side and the ring gear 20 meshing with the reduction gear 16 are composed of helical gears.

In the present embodiment, the differential device D is arranged coaxially with the rotor shaft 4 and the left and right output shafts 10L and 10R between the pair of counter shafts 14 constituting the twin counter structure in the gear case 2B. Here, the differential device D includes the spherical shell-shaped differential case 19 that can rotate around the axes of the left and right output shafts 10L and 10R, and the differential case 19 includes the left and right shaft insertion portions 19A and 19B. The outer periphery is rotatably supported by the gear case 2B by bearings (ball bearings) 21 and 22. The ring gear 20 is attached to the outer periphery of the differential case 19 by a plurality of bolts (only two are shown in FIG. 1) 23.

A pinion shaft 24 is inserted and fixed in the center of the differential case 19 in a direction orthogonal to the axis centers of the output shafts 10L and 10R (vertical direction in FIG. 1), and inside the differential case 19 by a pinion shaft 24. A pair of rotatably supported pinion gears (bevel gears) 25 and a pair of side gears 26 rotatably supported around the center of the output shafts 10L and 10R by meshing with each pinion gear 25 are accommodated. Here, the pair of pinion gears 25 are arranged at the top and bottom of FIG. 1 in the differential case 19, and the pair of side gears 26 are arranged on the left and right sides of the pinion shaft 24.

The ends of the left and right output shafts 10L and 10R are inserted into the left and right shaft insertion portions 19A and 19B of the differential case 19 and face the inside of the differential case 19, respectively, and the respective ends of these output shafts 10L and 10R. A pair of side gears 26 in the differential case 19 are connected to each other by spline fitting.

By the way, in the present embodiment, as shown in FIG. 2, the pair of counter shafts 14 constituting the twin counter structure are diagonal planes in which each axis passes through the rotor shaft 4 and the axes of the output shafts 10L and 10R. It is diagonally arranged so as to be tilted by the angle θ (25 ° in the present embodiment) shown in the figure with respect to the horizontal plane so as to be located above. Therefore, in the gear case 2B, a space is formed above the counter shaft 14 located on the lower side (right side in FIG. 2).

Therefore, in the present embodiment, as shown in FIGS. 3 and 4, the oil tank 27 is arranged in the space formed above the counter shaft 14 located below in the gear case 2B. This oil tank 27 is a closed type tank, and is for introducing the oil scooped up by the reduction gear 15 on the side surface facing the large diameter reduction gear 15 formed on the counter shaft 14 located below. An oil inlet 27a is formed, and an oil discharge port 27b for discharging the oil stored in the oil tank 27 toward the bearing (needle bearing) 18 is formed on the bottom surface of the oil tank 27. ing. Oil is stored in the bottom of the housing 2 to the level shown in FIG.

Next, the operation of the vehicle electric drive unit 1 configured as described above will be described.

When the electric motor 3 is supplied with power from a battery (not shown) to start the electric motor 3 when the EV vehicle is running, the rotor 3a rotates together with the rotor shaft 4, and the rotation of the rotor shaft 4 is decelerated by the deceleration mechanism T and is differential. It is transmitted to the device D. More specifically, the rotation of the rotor shaft 4 is decelerated by the pinion gear 8 of the rotor shaft 4 constituting the first-stage reduction gear group and the reduction gear 15 on the large diameter side of each pair of counters 14 meshing with the pinion gear 8. It is transmitted to each counter shaft 14. Then, each counter shaft 14 rotates at a predetermined speed, and the rotation is decelerated by the reduction gear 16 on the small diameter side of each counter shaft 14 constituting the two-stage reduction gear group and the ring gear 20 meshing with the reduction gear 16 to be a differential device. Since it is transmitted to the differential case 19 of D, the differential case 19 rotates at a predetermined speed. In the present embodiment, as described above, the reduction gear 16 on the small diameter side of each counter shaft 14 and the ring gear 20 that mesh with the reduction gear 16 are composed of helical gears, so that the reduction gear 16 and the ring gear 20 mesh with each other. The axial thrust forces generated in the above cancel each other out. Therefore, it is not necessary to use expensive thrust bearings for the bearings 21 and 22 that rotatably support the differential case 19 with respect to the gear case 2B, and ball bearings, which are inexpensive journal bearings, are used for these bearings 21 and 22. can do.

As described above, the rotation of the rotor shaft 4 rotating together with the rotor 3a of the electric motor 3 is decelerated by the deceleration mechanism T in two stages and transmitted to the differential case 19 of the differential device D, and when the differential case 19 rotates at a predetermined speed, the rotation thereof is increased. The rotation is distributed and transmitted to the left and right output shafts 10L and 10R, and is transmitted to the left and right drive wheels via the left and right output shafts 10L and 10R and the axles connected to them, respectively, so that the left and right drive wheels are predetermined. The EV vehicle is driven to rotate at the speed of the above and travels on the road surface.

In the differential device D, when the EV vehicle travels straight, the resistance received by the left and right drive wheels from the road surface is equal, so that the pair of pinion gears 25 revolve together with the differential case 19 to revolve between the pair of left and right side gears 26 and the output shaft. Rotational power is distributed to 10L and 10R and transmitted respectively. At this time, the pair of pinion gears 25 do not rotate (rotate).

On the other hand, when the EV vehicle is turning, a difference occurs in the resistance received from the road surface by the left and right drive wheels (difference in the moving distances of the left and right drive wheels), so that the pair of pinion gears 25 rotate on one side. The rotational speed of the side gear 26 is made faster than the rotational speed of the other side gear 26, and the rotational power is distributed and transmitted to the left and right output shafts 10L and 10R while smoothly cornering the EV vehicle.

By the way, when the pair of counter shafts 14 rotate, the reduction gear 15 on the large diameter side formed on the counter shafts (the counter shafts on the right side in FIGS. 2 and 3 and the counter shaft on the front side in FIG. 4) 14 arranged below rotates. Then, the oil stored in the bottom portion of the housing 2 is scooped up by the reduction gear 15. Then, a part of the pumped oil is introduced into the oil tank 27 from the oil introduction port 27a formed in the oil tank 27 shown in FIGS. 3 and 4, and is stored in the oil tank 27. It flies in the direction of the counter shaft 14 on the side.

Then, the oil stored in the oil tank 27 drops from the oil discharge port 27b (see FIGS. 3 and 4) formed on the bottom surface of the oil tank 27 toward the bearing (needle bearing) 18, and the bearing (needle). Bearing) 18 is provided for lubrication and cooling. Further, the oil flying toward the counter shaft 14 on the other side having a high height is used for lubricating and cooling the other bearing (needle bearing) 18 that rotatably supports the counter shaft 14 on the other side.

As described above, in the vehicle electric drive unit 1 according to the present embodiment, since the twin counter structure in which the pair of counter shafts 14 are arranged on the deceleration mechanism T is adopted, each of the planetary structure and the parallel shaft structure is adopted. It is possible to extract the merits and reduce the width dimension and the height dimension, and as a result, it is possible to realize the miniaturization of the electric drive unit 1 for the vehicle. In particular, in the present embodiment, since the pair of counter shafts 14 are arranged diagonally vertically and vertically symmetrically with respect to the rotor shaft 4 and the output shafts 10L and 10R, as shown in FIG. 2, the electric drive unit 1 for the vehicle is used. The total length L and the height H can be kept small.

Further, in the present embodiment, the oil tank 27 is arranged in the space formed above the lower counter shaft 14 in the gear case 2B, and scratched by the large-diameter side reduction gear 15 formed in the lower counter shaft 14. The oil to be fried is stored in an oil tank 27, and the oil stored in the oil tank 27 is dropped onto a bearing (needle bearing) 18 that rotatably supports the counter shaft 14 to lubricate and cool the bearing 18. Therefore, the oil pump for forced lubrication becomes unnecessary, and the number of parts can be reduced and the cost can be reduced. Since a part of the oil required for lubrication can be stored in the oil tank 27, the amount of oil stored in the bottom of the housing 2 as an oil bath can be small. As a result, the height of the oil level of the oil can be kept low, and the power loss due to the stirring resistance of the oil by the reduction gear 15 on the large diameter side of the counter shaft 14 can be kept small.

In addition, in the present embodiment, the differential device D is coaxial with the rotor shaft 4 and the output shafts 10L and 10R, and is arranged between the pair of counter shafts 14, so that the differential device D can be effectively used in space. It can be used and placed compactly.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of claims and the technical ideas described in the specification and drawings. Of course.

1 Electric drive unit for vehicles 2 Housing 3 Motor 4 Rotor shaft 8 Pinion gear 10L, 10R Output shaft 14 Counter shaft 15 Large diameter side reduction gear 16 Small diameter side reduction gear 18 Bearing (needle bearing)
19 Diff case 20 Ring gear 27 Oil tank 27a Oil tank oil inlet 27b Oil tank oil outlet D Differential device T Deceleration mechanism

Claims (5)

An electric drive unit for vehicles that transmits the rotation of the rotor shaft of the motor to the left and right output shafts via the deceleration mechanism and differential device.
The reduction mechanism includes a pair of counter shafts arranged parallel to the rotor shaft, and a plurality of reduction gears having different diameters, each of which is provided on each counter shaft .
The pair of counter axes are arranged diagonally with respect to the horizontal plane so that each axis is located on an oblique plane passing through the axis of the rotor axis, and is formed above one of the counter axes located below. An oil tank is arranged in the space, and an oil discharge port for discharging the oil stored in the oil tank toward the bearing supporting the counter shaft is formed on the bottom surface of the oil tank.
An electric drive unit for vehicles that is characterized by this. The reduction mechanism includes a pinion gear provided on the rotor shaft and meshes with the reduction gear on the large diameter side of the reduction gear, and a ring gear provided on the differential case of the differential device and meshes with the reduction gear on the small diameter side of the reduction gear. The electric drive unit for a vehicle according to claim 1, wherein the electric drive unit is provided. The electric drive unit for a vehicle according to claim 2 , wherein the differential device is arranged so as to penetrate the space inside the radial direction of the ring gear, which is defined by the ring gear . The electric drive unit for a vehicle according to any one of claims 1 to 3 , wherein the differential device is coaxial with the rotor shaft and arranged between the pair of counter shafts . The vehicle according to any one of claims 1 to 4 , wherein a reduction gear on the large diameter side of the reduction gear forms an oil introduction port on the side surface of the oil tank for introducing the pumped oil. Electric drive unit for.

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