JP3961719B2 - Axle structure of electric vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an axle structure of an electric vehicle, and more particularly to an axle structure of an electric vehicle in which a drive motor is accommodated in an axle case that supports drive wheels.
[0002]
[Prior art]
Known drive systems for electric vehicles include those in which the engine portion of an internal combustion engine-equipped vehicle is replaced with a drive motor, and wheel-directly connected electric vehicles that employ a motor with a wheel-directly connected reduction gear. Of these, the electric vehicle directly connected to the axle can be provided with a drive motor directly in the axle case that pivotally supports the drive wheels, thereby shortening the power transmission path. Moreover, this type of electric vehicle eliminates a differential with a relatively large power transmission loss, and further reduces the rotational force of the left and right drive motors supported by the axle case using a spur gear with a relatively small power transmission loss. It can be decelerated by the machine and transmitted to the left and right drive wheels, respectively.
[0003]
By the way, when an axle case accommodates a drive motor and a reduction gear, the motor case part which opposes a drive motor, and the reduction gear case part which opposes a reduction gear will comprise a comparatively big outer diameter. For example, the axle case of an electric vehicle disclosed in the publicity of No. 3-44562 is connected to the left and right individual drive motors in a state close to each other, and right and left speed reducers are provided adjacent to them. The entire main part has a relatively large outer diameter. The axle suspension used here is provided with a support frame that covers the same part outside the central portion of the axle case in the vehicle width direction, and a pair of front and rear leaf springs whose front and rear ends are directed in the vehicle width direction. It is connected to the vehicle body side via a vertical displacement.
[0004]
[Problems to be solved by the invention]
As described above, in the electric vehicle directly connected to the axle, the entire main part of the axle case or the vicinity of the left and right ends serving as the spring receiving portion has a relatively large outer diameter. For this reason, there are the following problems in attaching the axle of such an axle direct connection type electric vehicle to the vehicle body using the conventional axle suspension suspension as it is.
[0005]
That is, when the axle case has a relatively large outer diameter, if a conventional leaf spring type suspension suspension is used as the axle suspension suspension, the central portion of the leaf spring is largely occupied as a coupling tightening portion with the axle case. Therefore, the both side portions forming the spring function are greatly reduced. For this reason, in order to use a leaf spring type suspension device to ensure a predetermined spring constant, there is a problem that the leaf spring becomes very large and it is difficult to secure a mounting space. In consideration of this point, use a special suspension in which the axle case is attached to the vehicle body via a pair of front and rear leaf springs oriented in the vehicle width direction, as in the electric vehicle disclosed in the Publicity No. 3-44562 publication. Inevitably, the structure of the lower part of the vehicle body for mounting the suspension needs to be significantly changed from the conventional one, which causes a problem of increasing costs.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an axle structure for an electric vehicle that can be easily mounted on a vehicle body using an existing axle suspension suspension.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention of claim 1, as an axle structure of an electric vehicle, it is connected to left and right side members integrally coupled to a vehicle body floor so as to be movable up and down via a suspension device. An axle case, an electric motor as a drive source housed in the axle case, and a speed reducer that reduces the rotation of an axle that is coaxially connected to the electric motor and transmits the reduced speed to the wheels, and The left and right wheels of the vehicle that rotate by receiving the rotational force from the speed reducer are pivotally supported, and the axle case is disposed between the left and right side members and includes an electric motor case portion that houses the electric motor. a reducer case portion for accommodating the reduction gear, a bearing portion pivotally supporting the rolled out wheels from the reducer case portion, a between the electric motor case portion and the reducer case part of the left and right support An axle case portion for housing the axle, which is disposed so as to face the member and having a smaller outer diameter than both case portions, and a leaf spring mounting seat disposed on the outer wall surface of the axle case portion And are integrally coupled .
Here, between the electric motor case portion and the reduction gear case portion having a relatively large outer diameter, the axle case portion is disposed so as to face the left and right side members and has an outer diameter relatively smaller than both case portions. As a result, the vertical displacement of the rear axle can be kept large. Furthermore, an axle suspension suspension using a leaf spring can be provided in the same manner as a conventional vehicle in which a differential is housed in an axle without being affected by the electric motor case portion and the reduction gear case portion. For this reason, an axle suspension type suspension and a frame can be made common with the conventional vehicle using the axle which accommodated the differential, and cost reduction can be aimed at.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show a rear axle 1 to which an axle structure of an electric vehicle as an embodiment of the present invention is applied. The rear axle 1 is connected to left and right side members 3 and a cross member 4 integrally coupled to a rear floor 2 of an electric vehicle (not shown) via an axle suspension suspension 5 so as to be movable up and down.
As shown in FIG. 3, the axle suspension suspension 5 includes an impact absorbing mechanism including left and right leaf springs 6 and a shock absorber 8, which reduces the impact received by the vehicle occupant and improves comfortability. I am letting. A front end portion of the leaf spring 6 is pin-coupled to the left and right side members 3 via a spring bracket 9a, and a rear end portion is pin-coupled to the shackle ring 7 and attached to the left and right side members 3 via a bracket 9b.
[0008]
The rear axle 1 supported by such an axle suspension suspension 5 is a pair of left and right drives comprising an axle case 11, an electric motor 16 housed therein, first and second axle shafts 21 and 27, and a speed reducer 26. A force transmission system PT is provided, and the left and right wheels W _L and W _R that rotate by receiving the rotational force from the driving force transmission system PT are pivotally supported.
[0009]
The axle case 11 is a cylindrical member whose outer diameter increases and decreases in the vehicle width direction X. The electric motor case portion 12, the axle case portion 13, and the reduction gear case portion 14 extend from the vehicle width direction X center side toward the vehicle outer side. deploy the bearing portion 15 to a pair symmetrical, i.e., the wheel W _L of the left and right sides of the vehicle, there is which is disposed in correspondence with the W _R, is formed by integrally coupling the whole. Here, the left and right electric motor case sections 12 overlap with each other in a state in which the central side wall plates 121 and 121 in the vehicle width direction X are back to back, and the flange-shaped portion on the outer peripheral edge includes a plurality of bolts 37 (one in FIG. 2). Only a central cylinder portion having a relatively large outer diameter D1 is formed as a central portion of the axle case main body 11. The electric motor case section 12 accommodates an electric motor 16 that serves as a drive source for the left and right wheels W _L and W _R and functions as a case, and a rotary shaft 18 integrated with the rotor 17 is pivotally supported therein. A pair of left and right bearing frames 19 are provided. Reference numeral 20 denotes a cable for connecting the electric motor 16 to a motor control circuit (not shown).
[0010]
An axle case 13 having an outer diameter D2 in the vertical direction smaller than the outer diameter D1 extends from the bearing frame 19 from the end of the electric motor case 12 on the vehicle side. The bearing frame 19 projects a rotating shaft 18 from the central portion, and a tip portion thereof is connected to a first axle shaft 21 as an axle via a joint 20 so as to be integrally rotatable.
[0011]
As shown in FIG. 3, the axle case 13 has a hollow, semi-cylindrical cross-sectional shape, a seat 221 (see FIG. 3) of the damper 22 is in contact with the upper wall surface, and a leaf spring is mounted on the lower wall surface. 6 mounting seats 23 are integrally joined. A damper receiver 34 that restricts excessive displacement of the damper 22 is integrally joined to the side member 3. The seat portion 221, the axle case portion 13, the mounting seat 23, and the leaf spring 6 of the damper 22 are overlapped with each other and are fastened and coupled to each other by a pair of U-shaped bolts 24 and nuts 25. Here, the axle case portion 13 is formed to have a smaller vertical outer diameter D2 than the outer diameter D1 of the electric motor case portion 12. Thus, by holding the upper end of the axle case 13 at a relatively low position, it is possible to avoid interference between the axle case body 11, the side member 3 and the cross member 4 as shown by a two-dot chain line in FIG. A sufficient amount of upward displacement of the rear axle 1 can be secured. Furthermore, since the lower end of the axle case 13 is held at a relatively high position with respect to the road surface r, it is possible to prevent the minimum ground height h of the vehicle from being excessively lowered when the leaf spring 6 is attached. Furthermore, the axle case 13 has a sufficiently large vertical outer diameter D2 as compared to the outer diameter D3 in the front-rear direction Y, thereby preventing an excessive decrease in the bending rigidity of the axle case body 11. . Furthermore, the axle case portion 13 only accommodates the first axle shaft 21 therein, and the outer diameter D3 (see FIG. 3) in the front-rear direction Y is formed to be particularly small. As a result, the width (approximately the same width as the outer diameter D3) of the central tightening portion of the leaf spring 6 that overlaps the mounting seat 23 of the axle case portion 13 can be set relatively small with respect to the overall length L1, and the leaf that performs the spring function The elastically displaceable portions on both sides of the spring 6 can be secured sufficiently large. For this reason, a desired value of the spring constant can be secured without excessively increasing the overall length L1 of the leaf spring 6.
[0012]
The outer opening end of the axle case 13 extends so as to expand in the diameter increasing direction, and the reduction gear case 14 having an outer diameter D4 larger than the outer diameter D2 or the outer diameter D1 is continuously formed. The speed reducer case portion 14 has a hollow disk shape, and the outer end thereof has a reduced outer diameter, and a cylindrical bearing portion 15 having a relatively small diameter projects from the opening end of the reduced wall 143. The reduction gear case portion 14 has an outer peripheral end of the vehicle outer diameter expansion portion 141 integrated with the axle case portion 13 and an outer peripheral wall portion 142 of the reduction gear case portion 14 abutting each other. is doing.
[0013]
A reduction gear 26 composed of a planetary gear train is arranged inside the reduction gear case portion 14. The speed reducer 26 transmits the rotation of the first axle shaft 21 to the second axle shaft 27 with a predetermined reduction ratio. The sun gear 28 integrated with the first axle shaft 21 and the second axle shaft 27 are integrated with each other. A carrier 29, a planetary gear 30 that is pivotally attached to the carrier 29 and meshes with the sun gear 28, and a ring gear 31 that is integrally coupled to the inner circumferential wall of the outer peripheral wall 142 and meshes with the planetary gear 30.
[0014]
The bearing portion 15 has a fully floating axle shaft structure in which a second axle shaft 27 is rotatably fitted in a central hole, and a hub 32 h integrated with the second axle shaft 27 is pivotally supported on the outer peripheral side via a bearing 32. take. Note that the hub 32 h are coupled clamped hub bolts to the brake drum 33 and the wheel W _R is not shown.
In the above description, the right half of the rear axle 1 has been mainly described. However, the left half is also formed symmetrically, and redundant description is omitted here.
[0015]
In an electric vehicle (not shown) equipped with such a rear axle 1, the drive motors 16 that are drive sources of the left and right drive force transmission systems PT are respectively controlled to rotate, and the left and right wheels W _L and W _R rotate to run. To do. During this traveling, the wheel W _L of the left and right by the action of the axle suspension the suspension 5, the road surface reaction force from the W _R is absorbed, occupants ensuring during traveling can be achieved is attenuated. At this time, the rear axle 1 moves vertically in the vicinity of the normal running position P1, excessive road surface reaction force, for example the wheel and receives the left wheel W _L is displaced to the maximum upper position P2 side. At that time, the damper 22 abuts against the damper receiver 34 to prevent further excessive displacement. Here, since the outer diameter D2 in the vertical direction of the axle case 13 that opposes the side member 3 is formed to be relatively smaller than other parts, the rear axle 1 is displaced up and down without interfering with the side member 3 side. There is an advantage that a relatively large amount can be secured.
[0016]
When such a rear axle 1 is used, as shown in FIG. 4 (a), the electric motor case 12 and the reduction gear case 14 having relatively large outer diameters D1 and D4 are provided between the upper and lower sides and the front and rear sides. The axle case portion 13 with the outer diameters D2 and D3 set to be small was continuously formed so that the leaf spring 6 could be attached to the same. Therefore, even though the main portion of the rear axle 1 has a relatively large outer diameter, the differential 35 is used and the differential 35 is used as shown in FIG. The axle suspension type suspension 5 and the conventional frame 7 similar to the conventional vehicle housed in the center of the vehicle can be used as they are, and they can be used in common and contribute to the cost reduction.
[0017]
The rear axle 1 shown in FIG. 1 has a left and right half comprising the electric motor case portion 12, the axle case portion 13, the speed reducer case portion 14, and the bearing portion 15. In addition, in the reduction gear case part 14, the vehicle outer side enlarged diameter part 141 and the outer peripheral wall part 142 are integrally connected by the fastening bolt 50 and can be easily divided into two parts. For this reason, the rear axle 1 of FIG. 1 can be easily detached from the vehicle, and can be easily maintained and inspected.
[0018]
The rear axle 1 in FIG. 1 has a mounting seat 23 for the leaf spring 6 formed on the lower surface of the axle case portion 13, but a mounting seat for the leaf spring 6 may be formed on the upper surface of the axle case portion 13 according to circumstances. Further, although the axle suspension suspension 5 of FIG. 1 uses the leaf spring 6 combined with the air spring 7, an axle suspension suspension of only a leaf spring that excludes the vehicle height adjustment function may be used. Also, the same effect as the rear axle 1 of FIG. 1 can be obtained.
[0019]
【The invention's effect】
As described above, according to the first aspect of the present invention, both the case portions are disposed between the electric motor case portion and the reduction gear case portion having a relatively large outer diameter so as to face the left and right side members. Since the axle case portion having a relatively smaller outer diameter is provided, a large amount of vertical displacement of the rear axle can be secured. Furthermore, an axle suspension suspension using a leaf spring can be provided in the same manner as a conventional vehicle that houses a differential in the axle without being affected by the electric motor case portion and the speed reducer case portion. Axle suspension suspension and frame can be used in common with a conventional vehicle using, so that the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a main part of a rear axle to which an axle structure of an electric vehicle to which the present invention is applied and an axle suspension suspension coupled thereto;
FIG. 2 is an enlarged cross-sectional view of a main part of the rear axle of FIG.
3 is a schematic side view of a main part of the rear axle of FIG. 1 and an axle suspension suspension coupled to the rear axle. FIG. 4 shows a rear axle of the vehicle and an axle suspension suspension coupled thereto. (B) shows the case where the rear axle of an engine-driven vehicle using a differential is used for the driving force transmission system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rear axle 3 Side member 5 Axle suspension suspension 6 Leaf spring 12 Electric motor case part 13 Axle case part 14 Reduction gear case part 16 Electric motor 21 First axle shaft 23 Mounting seat 26 Reduction gear 27 Second axle shaft D2 Axle case part outer diameter W _L, W _R wheels vertical outer diameter D3 axle case portion longitudinal

Claims (1)

An axle case coupled to a left and right side member integrally coupled to the vehicle body floor via a suspension device so as to be movable up and down, an electric motor as a drive source housed in the axle case, and the electric motor And an axle of an electric vehicle that pivotally supports the left and right wheels of a vehicle that rotates by receiving rotational force from the speed reducer. In structure
The axle case is
An electric motor case portion disposed between the left and right side members and housing the electric motor;
A speed reducer case portion that houses the speed reducer;
A bearing that extends from the speed reducer case and pivotally supports the wheel;
Axle case part for accommodating the axle, which is disposed between the electric motor case part and the speed reducer case part so as to face the left and right side members and has a smaller outer diameter than both case parts. When,
A leaf spring mounting seat disposed on the outer wall surface of the axle case portion;
An axle structure for an electric vehicle, characterized in that is integrally formed .

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