Single-person electric vehicle
The π-shaped cross-section suspension arm with a single axial member simplifies the structure and reduces weight and costs in single-seater electric vehicles, enhancing ride comfort and stability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DAIHATSU MOTOR CO LTD
- Filing Date
- 2024-11-29
- Publication Date
- 2026-06-10
AI Technical Summary
Conventional single-seater electric vehicles face issues with large size, increased weight, and high manufacturing costs due to complex suspension systems, and ride comfort is compromised by poor rotational movement of suspension arms in independent suspension types.
A single-seater electric vehicle with an independent suspension system featuring a suspension arm with a π-shaped cross-section and a single axial member as the rotation center, simplifying the structure while ensuring stability and strength, thereby reducing weight and costs.
The simplified suspension design achieves a lightweight, cost-effective, and comfortable ride by stabilizing rotational movement and reducing unsprung weight, improving ride quality without the need for complex coaxial precision.
Smart Images
Figure 2026094653000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a single-seater electric vehicle. In addition, the single-seater electric vehicle referred to in this specification is generally an electric vehicle called a senior car or an electric wheelchair. The self-propelled steering-wheel type electric wheelchair of the Japanese Industrial Standard and the wheelchair for disabled persons using a motor in the Road Traffic Law correspond to this.
Background Art
[0002] In many conventional single-seater electric vehicles, the rear suspension is of the rigid axle type. In this system, since a pair of left and right rear wheels are connected via a single axle, although it is suitable for simplifying the overall configuration, when one of the rear wheels strokes up and down due to an input to one side rear wheel, the other rear wheel is directly affected and strokes up and down. Therefore, the vehicle shakes greatly during running and the riding comfort is not very good. On the other hand, the rear suspension of the single-seater electric vehicle described in Patent Document 1 is of an independent suspension type that individually supports each of a pair of left and right rear wheels. According to this independent suspension type, it is possible to improve the riding comfort of the vehicle compared to the rigid axle type.
[0003]
[0005] However, in the above prior art, as described below, there is still room for improvement.
[0004] That is, in the independent suspension type rear suspension described in Patent Document 1, the suspension arm that supports each rear wheel has an arm rotation support portion (pivot portion) at its front end, and a rear wheel is attached to the side portion of the rear end. For this reason, the overall length of the suspension arm in the vehicle front-rear direction is somewhat long, and the overall size tends to be relatively large. Therefore, the weight of the vehicle increases and the manufacturing cost becomes high. Furthermore, some independent rear suspension systems for ordinary automobiles include a suspension arm to which the rear wheel is attached at the end on the outer side in the vehicle width direction, and the base end on the inner side in the vehicle width direction is rotatably connected to a vehicle body side member (see, for example, Patent Document 2). However, this suspension arm has a configuration in which the front and rear ends of the base are individually rotatably connected to the vehicle body member. As a result, the structure is complex and the manufacturing cost is high. Furthermore, if the coaxial precision of the suspension arm's rotation support points is not high enough, the rotational movement of the suspension arm will be poor, and the smoothness of the rear wheel's vertical stroke will be reduced. This is not desirable for improving the ride comfort of the vehicle. [Prior art documents] [Patent Documents]
[0006] [Patent Document 1] International Publication No. WO2022 / 208876 [Patent Document 2] Japanese Patent Publication No. 2023-160024 [Patent Document 3] Japanese Utility Model Publication No. 62-76079 [Patent Document 4] Japanese Patent Publication No. 2007-230538 [Patent Document 5] Japanese Patent Publication No. 2006-103374 [Patent Document 6] Japanese Patent Publication No. 2002-46444 [Overview of the project] [Problems that the invention aims to solve]
[0007] This invention was conceived under the circumstances described above, and is a rear suspension The challenge is to provide a single-seat electric vehicle that has a simple structure, is lightweight, reduces manufacturing costs, and also offers a comfortable ride. [Means for solving the problem]
[0008] To solve the above problems, the present invention employs the following technical measures.
[0009] The single-seat electric vehicle provided by the present invention is equipped with an independent suspension type rear suspension that individually supports each of a pair of left and right rear wheels, the rear suspension comprising a suspension arm to which the rear wheel is attached at the tip end, which is on the outward side in the vehicle width direction, and an arm rotation support part that rotatably connects the base end, which is on the inward side in the vehicle width direction, of the suspension arm to the vehicle body side member in order to enable relative vertical movement between the rear wheel and the vehicle body side member, the single-seat electric vehicle, wherein the suspension arm is in the vehicle width direction and the vehicle The arm rotation support portion is characterized by having a main plate portion that has width in the front-rear direction and thickness in the vertical height direction or diagonal vertical height direction, and a substantially Π-shaped cross-section portion having a front plate portion and a rear plate portion that extend downward from the front edge and rear edge of the main plate portion, respectively, and the arm rotation support portion is equipped with a single shaft-shaped member that is attached to the vehicle body side member and extends in the front-rear direction of the vehicle and serves as the rotation center of the suspension arm, and this single shaft-shaped member is connected to the suspension arm in a manner that spans both the front plate portion and the rear plate portion.
[0010] The single-seat electric vehicle that is the subject of this invention is designed to operate at very low speeds, such as a speed limit of 6 km / h or less. Therefore, unlike ordinary passenger cars, it is not necessary to place importance on rear wheel toe changes due to compliance in order to control the vehicle's behavior during operation. This invention focuses on this point and aims to simplify the configuration of the rear suspension, thereby achieving the following effects. In other words, the suspension arm constituting the rear suspension has a roughly π-shaped cross-section with a predetermined main plate, front plate, and rear plate. This simplifies the overall structure of the suspension arm while increasing rigidity and ensuring sufficient strength. Furthermore, the base end of the suspension arm is connected to the vehicle body side member via an arm rotation support. This arm rotation support has a simple structure because it uses a single axial member as its center of rotation. Moreover, unlike cases where two centers of rotation are provided, there is no risk of impairing the rotational movement of the suspension arm and the smoothness of the vertical stroke of the rear wheel due to poor coaxial accuracy. In addition, since the axial member is connected to the suspension arm in a manner that spans both the front and rear plate portions of the suspension arm, it is possible to stably support the rotation of the suspension arm. As a result, it is possible to simplify the structure of the rear suspension of a single-seat electric vehicle, reduce weight (including unsprung weight), lower manufacturing costs, and improve ride comfort.
[0011] Other features and advantages of the present invention will become more apparent from the description of embodiments of the invention given below with reference to the accompanying drawings. [Brief explanation of the drawing]
[0012] [Figure 1] This is a schematic side view showing an example of a single-person electric vehicle according to the present invention. [Figure 2] Figure 1 is a schematic perspective view of the main components of the rear suspension system installed in the single-seat electric vehicle shown (rear wheel hubs, motors, etc. are omitted). [Figure 3] (a) is a schematic plan view of the main parts of the rear suspension shown in Figure 2, (b) is a cross-sectional view of the vehicle in the front-rear direction, and (c) is a cross-sectional view of (a) from IIIc-IIIc. [Figure 4] (a) is a cross-sectional view of IVa-IVa in Figure 2 (rear wheel hub, motor, etc. are omitted), and (b) is a cross-sectional view of IVb-IVb in Figure 2 (rear wheel hub, motor, etc. are omitted). [Figure 5] It is a schematic perspective view of the main components of the rear suspension shown in FIGS. 2 to 4. [Figure 6] It is a sectional view of the main part showing another example of the present invention.
Mode for Carrying Out the Invention
[0013] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.
[0014] The single-seater electric vehicle A shown in FIG. 1 is an electric vehicle called a senior car and corresponds to a self-operated steering wheel-type electric wheelchair under the Japanese Industrial Standards. This single-seater electric vehicle A has a pair of left and right rear wheels 1 below or obliquely below the seat 12, and an independent suspension-type rear suspension S that individually supports each of these pair of rear wheels 1. In FIG. 1, reference numerals 13 and 14 indicate the front wheels and the steering wheel, respectively.
[0015] As shown in FIGS. 2 to 4, the rear suspension S includes a suspension arm 2 that supports the rear wheel 1, an arm rotation support portion RS, and a coil spring 3. The illustrated rear wheel 1 is the rear wheel on the right side. The rear suspension S is symmetric left and right, and the illustration description for the rear wheel on the left side is omitted.
[0016] The suspension arm 2 is formed, for example, by pressing a metal plate, and has a main plate portion 20, a front plate portion 21, and a rear plate portion 22. Substantially the entire suspension arm 2 has a substantially U-shaped cross-section (see FIGS. 4 and 5). The main plate portion 20 has a width in the vehicle width direction and the vehicle longitudinal direction, and is substantially flat with the vertical height direction or the vertical height diagonal direction as the plate thickness direction. The front plate portion 21 and the rear plate portion 22 are plate-like portions that bend downward and extend from the front edge portion and the rear edge portion of the main plate portion 20, respectively, and are integrally formed with the main plate portion 20. These front plate portion 21 and rear plate portion 22 also extend continuously in the vehicle width direction, and their vertical width Ha has a shape that is wide on the tip side (outer side in the vehicle width direction) and narrow on the base end side (inner side in the vehicle width direction). Notched or non-notched openings 23a to 23c are appropriately provided in the suspension arm 2 to achieve weight reduction.
[0017] An end plate 4 is welded to the tip of the suspension arm 2, and the rear wheel 1 is attached to the tip side of the suspension arm 2 using this end plate 4. As shown in FIG. 5, the end plate 4 has a frame shape with an opening 40 in the central portion and has a plurality of bolt insertion holes 41. As shown in FIGS. 3(a) and 3(b), the drive system of this single-seater electric vehicle A is an in-wheel motor system in which a motor M is mounted on the hub 10 of the rear wheel 1. The motor M or the hub 10 is attached to the end plate 4, and for this attachment, the bolt insertion holes 41 described above and corresponding bolts 41a are used.
[0018] The arm rotation support part RS is the part that connects and supports the base end of the suspension arm 2 to the bracket part 5 on the vehicle body side so that the rear wheel 1 can stroke up and down. The bracket part 5 corresponds to a specific example of the "vehicle body side member" in the present invention, and as is clearly shown in Figure 2, it has a pair of support plate parts 50 that are spaced apart and facing each other in the front-rear direction, bolt insertion holes 51 provided in them, and a connecting plate part 52 that connects the pair of support plate parts 50. As shown in Figure 3(b), this bracket part 5 is attached to the first vehicle body frame part 6A, which is made of pipe material, for example, by means of welding. Preferably, the bracket portion 5 is used not only for attaching the right suspension arm 2, but also for attaching the left suspension arm 2 (the dashed line CL1 in Figure 3(b) is the vehicle's centerline). This further reduces the number of parts in the rear suspension S.
[0019] The arm rotation support part RS is attached to the suspension arm 2 using bolts 7 and nuts 70. The base end is attached to the bracket portion 5 on the vehicle body side, and more specifically, it has the following configuration. Note that the bolt 7 corresponds to a specific example of the "shaft-shaped member" as defined in this invention. Specifically, a first collar 8a is fixed to the base ends of the front plate portion 21 and rear plate portion 22 of the suspension arm 2 by welding or the like, bridging the gap between the base ends. Inside the first collar 8a, a second collar 8b is fitted via a sleeve 80 for wear resistance and reduced rotational sliding (see Figures 3(c) and 5). A bolt 7 is inserted through the second collar 8b, and the first and second collars 8b are fastened together using the bolt 7 and nut 70 while sandwiched between a pair of support plate portions 50 of the bracket portion 5. The bolt 7 serves as the rotational axis of the suspension arm 2 and extends in the longitudinal direction of the vehicle (the center line CL2 of the bolt 7 shown in Figures 2 and 3(a) extends in the longitudinal direction of the vehicle).
[0020] The coil spring 3 is a suspension spring that absorbs vibrations and shocks from the road surface, and is connected as a bridge between the suspension arm 2 and the second vehicle body frame section 6B located above it. As a means of attaching the lower part of the coil spring 3 to the suspension arm 2, a bracket section 90 for the coil spring 3 is provided on the suspension arm 2. This bracket section 90 has, for example, a roughly U-shaped cross-section, and its bottom is joined to the main plate section 20 of the suspension arm 2 by means of welding or other means.
[0021] Preferably, the lower portion of the suspension arm 2 where the bracket portion 90 is attached is reinforced with a reinforcing member 91. This reinforcing member 91 is a bent plate having a vertical plate portion 91a and a horizontal plate portion 91b. The upper end of the vertical plate portion 91 is joined to the main plate portion 20, and the outer end of the horizontal plate portion 91b is joined to the front plate portion 21. This reinforcing member 91 and the suspension arm 2 form a closed cross-sectional structure with high strength (see Figure 4(b)). The reinforcing member 91 extends from the lower side of the bracket portion 90 to a position where it contacts or approaches the first collar 8a (see Figure 3(b)), effectively reinforcing the area around the load concentration point of the coil spring 3.
[0022] Next, the operation of the aforementioned single-person electric vehicle A will be explained.
[0023] The rear suspension S, when subjected to vertical input from the road surface to the rear wheel 1, causes the suspension arm 2 to rotate vertically around the arm rotation support RS as a pivot point, allowing for vertical stroke of the rear wheel 1. This rear suspension S is an independent suspension type, and like independent suspensions used in general automobiles, when an input is applied to one side of the pair of rear wheels 1, the opposite rear wheel 1 is not affected and does not experience a large vertical stroke. Therefore, it is possible to improve ride comfort compared to a rigid axle type.
[0024] The suspension arm 2, which constitutes the rear suspension S, has a roughly π-shaped cross-section consisting of a main plate portion 20, a front plate portion 21, and a rear plate portion 22. Although its structure is simple, it is possible to achieve high rigidity. An end plate 4 is joined to the tip of the suspension arm 2, and a first collar 8a is joined to the base portion in a bridging manner. These components also effectively improve the strength of the suspension arm 2. Therefore, as a suspension arm 2 for a single-person electric vehicle A, it is possible to achieve weight reduction while ensuring sufficient strength.
[0025] The arm rotation support part RS, which rotatably supports the suspension arm 2, has a simple configuration with a single bolt 7 as the center of rotation. Furthermore, if there are, for example, two centers of rotation, poor coaxial accuracy between them can result in the rotation of the suspension arm 2 being uneven, but according to this embodiment, there is no such risk, and the rotational movement of the suspension arm 2 is smooth. This makes it possible to smooth the vertical stroke of the rear wheel 1. Furthermore, the bolt 7 is connected to the suspension arm 2 in a manner that spans both the front plate portion 21 and the rear plate portion 22 of the suspension arm 2, and its rotational axis is long. As a result, the connection and support state of the suspension arm 2 to the bolt 7 can be stabilized, and the operation when the suspension arm 2 rotates can also be made stable, resulting in improved smoothness.
[0026] As mentioned above, the rear suspension S has a simple configuration. However, as previously stated, the single-seat electric vehicle A is designed to operate at very low speeds, such as being limited to 6 km / h or less. Therefore, it is not necessary to prioritize factors such as toe changes of the rear wheel 1 in order to handle high-speed operation. For this reason, the rear suspension S can be designed to have the necessary and sufficient suspension performance for the single-seat electric vehicle A. Because the configuration of the rear suspension S can be simplified, it is also possible to effectively reduce weight and manufacturing costs.
[0027] In the aforementioned rear suspension S, by using, for example, an eccentric bolt as the bolt 7, the center line of the bolt 7 can be inclined by an appropriate angle α with respect to the vehicle's longitudinal direction, as shown by the dashed line La in Figure 3(a). An example of such an eccentric bolt is a bolt with an eccentric cam portion on the shaft or head, which is a bolt (referred to as a camber bolt) used to set and change the camber angle of the wheels of a general automobile. With this configuration, it is possible to set the rear wheel 1 to toe-out or toe-in.
[0028] Figure 6 shows another embodiment of the present invention. In this figure, elements identical or similar to those in the above embodiment are denoted by the same reference numerals as those in the above embodiment of the light guide member, and redundant explanations are omitted.
[0029] In the embodiment shown in Figure 6, the bolt 7 directly penetrates the front plate portion 21 and the rear plate portion 22 of the suspension arm 2, and the first and second collars 8a, 8b and sleeve 80 of the above embodiment are not used. According to this embodiment, the configuration can be further simplified. In this embodiment as well, the suspension arm 2 can be rotated around the bolt 7, similar to the embodiment described above. As can be seen from this embodiment, in the present invention, it is possible to omit all or part of the first and second collars 8a, 8b and the sleeve 80 of the embodiment described above as appropriate.
[0030] The present invention is not limited to the embodiments described above. The specific configuration of each part of the single-person electric vehicle according to the present invention can be modified in various ways within the scope intended by the present invention.
[0031] In the embodiments described above, a bolt is used as the shaft-like member in the present invention, but other shaft-like members (for example, a pin with a locking ring attached to its tip, a pin with a crimped tip, etc.) can also be used. The suspension arm in this invention only needs to have a portion with a substantially π-shaped cross-section having a predetermined main plate portion, a front plate portion, and a rear plate portion, and may have additional parts provided. In the embodiments described above, the vehicle drive system is an in-wheel motor system, but it is not limited to this. The definition of a single-person electric vehicle as used in this invention is as stated in the [Technical Field] section at the beginning. [Explanation of symbols]
[0032] A single-person electric vehicle S Rear Suspension RS Arm Rotation Support Unit 1 Rear wheel 2 Suspension arms 20 Main plate part 21 Front plate part 22 Rear plate part 5. Bracket section (vehicle body side component) 7. Bolt (shaft-shaped member)
Claims
[Claim 1] It features an independent rear suspension system that individually supports each of the left and right rear wheels. The aforementioned rear suspension is A suspension arm to which the rear wheel is attached on the front end side, which is on the outward side in the vehicle width direction, In order to enable relative vertical movement between the rear wheel and the vehicle body side member, an arm rotation support part is provided which rotatably connects the base end side of the suspension arm, which is on the inward side in the vehicle width direction, to the vehicle body side member, A single-seat electric vehicle equipped with, The suspension arm has a main plate portion that has width in the vehicle width direction and in the vehicle longitudinal direction, and thickness in the vertical height direction or diagonal vertical height direction, and a portion with a substantially Π-shaped cross-section that has a front plate portion and a rear plate portion that extend downward from the front edge portion and rear edge portion of the main plate portion, respectively. A single-seat electric vehicle, characterized in that the arm rotation support portion is provided with a single shaft-shaped member attached to the vehicle body side member, extending in the longitudinal direction of the vehicle, and serving as the rotation center of the suspension arm, and this single shaft-shaped member is connected to the suspension arm in a manner that spans both the front plate portion and the rear plate portion.