Buffer device for a small electric vehicle

Abstract

To provide a space-saving shock absorber suitable for a wheel cantilevered by an axle extending laterally on the lower side of a vehicle body.SOLUTION: A shock absorber (51) for a wheel (5) of a small electric vehicle (1) comprises: a base member (52) to be fixed to a vehicle body (25); a movable member (53) by which an axle (5a) is supported or fixed, which comes into slide contact with the base member via a slide contact surface (52b) perpendicular to the axle and is connected to the base member swingably about a shaft (53a) parallel to the axle; and a spring (54) disposed between the base member (52) and the movable member (53). The base member (52) and the movable member (53) include recesses (524 and 534) facing the slide contact surface and including a common area, and the spring (54) is stored in hollow parts (524 and 534) delimited by the base member-side recess (524) and the movable member-side recess (534), such that a direction intersecting with a radial direction centered on the shaft becomes a direction of elastic compression.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a shock absorber for wheels of a small electric vehicle.

Background Art

[0002] Wheelchairs, electric wheelchairs, and pushcart-type walking aids for users who have a burden on walking, such as the elderly, are known. For example, Patent Document 1 discloses a wheelchair having a shock absorption structure for caster-type wheels. Such a shock absorption structure is constituted by a spring provided between the base of the caster disposed at the lower part of the vehicle body and a bracket.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described shock absorption structure is suitable for non-electric vehicles with sufficient space in the lower part of the vehicle body. However, in a small electric vehicle equipped with a battery and a drive system in the lower part of the vehicle body, since the wheels are cantilever-supported on an axle extending laterally at a relatively low position in the lower part of the vehicle body, it is impossible to adopt the above-described shock absorption structure.

[0005] The present invention has been made in view of the above points of the prior art, and an object thereof is to provide a space-saving shock absorber suitable for wheels cantilever-supported on an axle extending laterally at the lower part of the vehicle body.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention provides a shock absorber for wheels of a small electric vehicle, A base member fixed to the vehicle body, a movable member in which an axle is supported or fixed, which is in sliding contact with the base member via a sliding contact surface perpendicular to the axle, and which is connected so as to be swingable about an axis parallel to the axle, and a spring disposed between the base member and the movable member so as to be elastically compressed by the swinging of the movable member. In this case, the base member and the movable member have recesses facing each other and including a common region on the sliding contact surface, and the spring is accommodated in a hollow portion defined by the base member side recess and the movable member side recess such that a direction intersecting the radial direction centered on the axis is the elastic compression direction.

Advantages of the Invention

[0007] As described above, the buffer device according to the present invention is configured to be accommodated in a hollow portion defined by a base member side recess and a movable member side recess facing each other and including a common region on a sliding contact surface perpendicular to the axle. Thus, the buffer device can be configured substantially within the range of the widths (thicknesses) of the base member and the movable member, and a space-saving buffer device can be provided. Further, since the movable member is in sliding contact with the base member via the sliding contact surface, it is advantageous in securing the lateral mounting rigidity of the movable member and the wheel while saving space.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (Basic Configuration of Small Electric Vehicle) FIG. 1 shows a small electric vehicle 1 equipped with a buffer device 51 according to an embodiment of the present invention. The small electric vehicle 1 includes a vehicle body 2 composed of a moving base 21 (lower traveling body) and an upper frame 22 erected on the rear portion (rear side base 24) thereof, and can be used in a small electric vehicle mode (riding mode 1) shown by a solid line in the figure and a walking assist vehicle mode (1′) shown by a two-dot chain line in the figure.

[0010] The moving base 21 includes a rear side base 24 (main body portion) provided with left and right rear wheels 4 (drive wheels) and an upper frame 22, and a front side base 25 provided with left and right front wheels 5 (driven wheels). The front side base 25 is slidably connected in the front-rear direction to the front side of the rear side base 24, and the wheelbase is configured to be expandable and contractible. The left and right rear wheels 4 are independently driven by left and right motor units 40 mounted on the rear side base 24. The left and right front wheels 5 are composed of free wheels (omni wheels, all-directional wheels) provided with a large number of rollers 50 rotatable around the axis in the circumferential direction at the grounding portion, and the small electric vehicle 1 can be steered and driven only by controlling the left and right motor units 40. The left and right front wheels 5 are rotatably supported on the side portions of the front side base 25 via buffer devices 51, respectively.

[0011] The upper frame 22 has an inverted U-shape or a portal shape in which the upper ends of a pair of left and right side frames erected upward from both left and right sides of the rear base 24 are connected by a horizontal portion 22a. A stem 31 of the rear handle 3 is rigidly connected to a coupling portion 23 at the center in the vehicle width direction of the horizontal portion 22a. The left and right gripping portions of the rear handle 3 are provided with a gripping sensor 30 and serve as an operation portion when the user himself uses it in the walking assistance vehicle mode (1') or when an assistant operates it with the user seated on the seat 7. A seat back 36 that serves as a backrest for the user in the riding mode (1) is provided at the front of a connecting portion 32 at the center of the rear handle 3.

[0012] At the bent portion in the middle in the height direction of the upper frame 22 (side frame), the base of a support frame 81 of the armrest 82 is fixed. A joystick 83 that constitutes an operator of the riding mode operation portion 8 is provided at the front end of the right armrest 82 on the back side in FIG. 1, and a display portion 80 is provided on the upper surface of a gripping portion having the same shape at the front end of the left armrest 82 on the front side in FIG. 1, and a travel permission switch 84 is provided on the front surface of the gripping portion.

[0013] A movable frame 71 that serves as a support structure for the seat 7 (seat cushion) is pivotally supported by a shaft 7a in the vehicle width direction at a pivot support portion 27 that protrudes forward from the bent portion of the upper frame 22 (side frame). On the other hand, the lower end of the movable frame 71 is rotatably and slidably connected to the front base 25 (pin) via a connecting portion 7b (slot). When the seat 7 in the riding mode (1) shown by the solid line in the figure is rotated forward and downward to the folded position (7') shown by the two-dot chain line in the figure, the front base 25 slides backward in conjunction with it, the moving base 21 is shortened, and the walking assistance vehicle mode (1') is entered.

[0014] On the one hand, when the seat (7′) in the folded position is rotated upward and backward from the walking assistance vehicle mode (1′) to move to the seating position 7, the front base 25 slides forward and the moving base 21 extends to enter the riding mode (1). In this state, the upper surface 25b of the front base 25 that has moved forward of the tray 24b can be used as a footrest for the passenger.

[0015] A battery (not shown) is mounted inside the moving base 21. Further, a locking mechanism for locking the front base 25 at each of the extended position and the retracted position is provided inside the moving base 21, and a biasing member for biasing the front base 25 in the intermediate position direction (release direction) is provided at each of the extended position and the retracted position. When the release tag 26 is pulled to release the locking mechanism at each position, the vehicle body 2 assumes the intermediate position. From this state, when the seat 7 (movable frame 71) is rotated forward / backward, the locking mechanism is configured to be locked at the extended position / retracted position of the front base 25.

[0016] Also, as shown in FIG. 1, a net-like loading portion 6 that is folded (6′) in the riding mode (1) and is deployed and available in the walking assistance vehicle mode (1′) is provided between the horizontal portion 22a of the upper frame 22 and the horizontal portion 71a of the movable frame 71. A cushion 66 for cushioning the waist of the user seated on the seat 7 in the riding mode (1) against the horizontal portion 71a of the movable frame 71 is provided at the connecting portion of the front end portion of the loading portion 6 with the movable frame 71 (horizontal portion 71a).

[0017] In the riding mode (1), the grip sensor 30 is disabled. When the travel permission switch 84 is turned on, the left and right motor units 40 are controlled by the operation (operation amount, operation direction) of the joystick 83 that constitutes the riding mode operation unit 8, and driving operations including forward movement, backward movement, turning, and braking stop of the small electric vehicle 1 can be performed. On the other hand, in the walking assistance vehicle mode (1′), the riding mode operation unit 8 is disabled, and torque control of the left and right motor units 40 is executed based on detection information such as left and right rotation speed sensors and a predetermined control map.

[0018] As described above, the small electric vehicle 1 includes a front wheel 5 configured as an omnidirectional wheel (omni wheel) that is slidably connected in the front-rear direction to the front side of the rear base 24. The left and right rear wheels 4 mounted on the rear base 24 are independently driven by the left and right motor units 40, so that steering and driving are performed. Therefore, not only the impact from the front caused by road surface unevenness and the like but also the lateral force act on the shock absorber 51 of the front wheel 5 (driven wheel) via the roller 50 during turning. Moreover, the front wheel 5 is cantilever-supported on the side of the front base 25, and the shock absorber 51 needs to be arranged in the limited space between the front base 25 and the front wheel 5.

[0019] (Basic Structure of Shock Absorber) Therefore, as shown in FIGS. 2 to 4, the shock absorber 51 according to the present invention includes a base member 52 fixed to the front base 25 constituting the vehicle body 2 of the small electric vehicle 1, a movable member 53 that is slidably contacted with the base member 52 via a plane perpendicular to the axle 5a and is swingably connected to the base member 52 about an axis 53a parallel to the axle 5a, and a spring 54 disposed between the base member 52 and the movable member 53.

[0020] The base member 52 includes a main portion 521 having a relief hole 520 at the center and three fixing holes 529, one on the upper side and two on the lower side, and an extending portion 522 extending from one side thereof. A screw hole 52a for fastening the swing shaft 53a (screw shaft) of the movable member 53 is provided between the main portion 521 and the extending portion 522.

[0021] The movable member 53 includes a first arm portion 531 extending obliquely rearward and downward from the swing shaft 53a, and a second arm portion 532 extending forward from the swing shaft 53a. The second arm portion 532 is formed in a shape conforming to the extending portion 522 of the base member 52. As shown in FIG. 5, the movable member 53 is connected to the base member 52 so as to be swingable about the swing shaft 53a (screw shaft) by fastening the swing shaft 53a (screw shaft) to the screw hole 52a of the base member 52 via washers 53c and 53d with a boss 53b fitted in the central support hole 530. The base 5b of the axle 5a is fitted and fixed in the bearing hole 5c at the tip of the first arm portion 531.

[0022] In the embodiment, with the movable member 53 swingably connected to the base member 52, the first arm portion 531 is in sliding contact with the main portion 521 of the base member 52, and the second arm portion 532 is in sliding contact with the extending portion 522 of the base member 52. Therefore, almost the entire adjacent surface of the base member 52 with the movable member 53 serves as a sliding contact surface 52b that is in sliding contact with the movable member 53.

[0023] The base member 52 and the movable member 53 have recesses 524 and 534 on the sliding contact surface 52b, which include a common region (a region that overlaps in a side view) on the extending portion 522 of the base member 52 and the second arm portion 532 of the movable member 53 in the embodiment. A spring 54 is accommodated in the hollow portion (524, 534) defined by the base member side recess 524 and the movable member side recess 534.

[0024] The spring 54 is a compression spring and is accommodated in the recesses 524 and 534 such that the elastic compression direction is substantially the swinging direction of the movable member 53 (a direction intersecting the radial direction centered on the swing shaft 53a). Disk-shaped plates 523 and 533 are provided at each end of the spring 54. One end of the spring 54 is supported on the inner surface of the base member side recess 524 via the plate 523, and the other end of the spring 54 is supported on the inner surface of the movable member side recess 534 via the plate 533. Note that the plates 523 and 533 may be retainers that engage with the ends of the spring 54, or may be fixed to the inner surfaces of the corresponding recesses 524 and 534 by welding or the like.

[0025] As shown in FIG. 6, the base member side recess 524 and the movable member side recess 534 have an inner peripheral side surface 534a and an outer peripheral side surface 534b that extend in an arc shape centered on the shaft 53a, and the lateral displacement of the spring 54 is restricted by these inner peripheral side surface 534a and outer peripheral side surface 534b. In this way, since the inner peripheral side surface 534a and the outer peripheral side surface 534b of the base member side recess 524 and the movable member side recess 534 form an arc shape, even if the movable member 53 swings, the shapes of the inner peripheral side surface 534a and the outer peripheral side surface 534b of the base member side recess 524 and the movable member side recess 534 do not change, and the middle portion of the spring 54 can be guided in a constant shape.

[0026] In the embodiment, the base member 52 and the movable member 53 are made of, for example, a metal plate (thick steel plate). As shown in FIG. 5, the respective recesses 524 and 534 are formed as openings (through holes) that penetrate the base member 52 and the movable member 53, and a hollow portion (524, 534) is defined by closing the openings with separate cover members 525 and 535. The cover members 525 and 535 are each composed of a frame portion 526 and 536 and a lid portion 527 and 537, and are fixed to the base member 52 and the movable member 53 with screws or the like. With such a configuration, by detaching either of the cover members 525 and 535, it is possible to access the hollow portion (524, 534) in the state where the buffer device 51 is configured, and the spring 54 can be attached and detached.

[0027] In the embodiment, as shown in FIGS. 2, 3, and 5, the buffer device 51 is fixed to the side surface of the front base 25 of the small electric vehicle 1 with bolts 58b through spacers 56 at three fixing holes 529 of the base member 52. With this configuration, even in an embodiment where the base member 52 and the movable member 53 are made of a substantially uniform thickness metal plate (thick steel plate), there is an advantage that a stable attachment conforming to the shape of the attachment portion on the vehicle body side (the side surface of the front base 25) is possible. In an embodiment where the base member 52 is composed of a press-formed part, a forged part, or the like, a portion corresponding to the spacer 56 may be integrally formed on the base member 52.

[0028] The fender 55 is fixed to the movable member 53 by screws or the like (not shown). After the shock absorber 51 is fixed to the vehicle body (front base 25), the front wheel 5 is mounted on the axle 5a.

[0029] When an impact caused by road surface unevenness or the like acts on the front wheel 5 during running of the small electric vehicle 1 equipped with the shock absorber 51 configured as described above, the first arm portion 531 of the movable member 53 swings upward about the swing shaft 53a from the non-operating position as shown by the solid line in FIG. 2 (or the two-dot chain line in FIG. 6), and at the same time, the second arm portion 532 integrated with the first arm portion 531 swings downward. Along with this, as shown by the solid line in FIG. 6, the spring 54 is pressed via the plate 533 by the upper edge 534c of the concave portion 534 of the second arm portion 532 that has swung downward, and the spring 54 is compressed between the lower edge 524d (plate 523) of the concave portion 524 of the base member 52, and the impact acting on the front wheel 5 is absorbed by such elastic deformation of the spring 54.

[0030] After that, when the front wheel 5 passes over road surface unevenness or the like, the second arm portion 532 of the movable member 53 swings upward and the first arm portion 531 swings downward due to the elastic recovery of the spring 54, pushing down the front wheel 5. Due to the elastic deformation and elastic recovery of the spring 54 accompanying the swing of the movable member 53 as described above, the impact acting on the front wheel 5 due to road surface unevenness or the like is alleviated, the transmission to the vehicle body 2 and the occupant is suppressed, and the followability of the wheel 5 to the road surface is ensured.

[0031] FIG. 7 is a cross-sectional view showing the non-operating state (a) of the shock absorber 51 in which the second arm portion 532 (concave portion 534) of the movable member 53 is in the same position as the extension portion 522 (concave portion 524) of the base member 52, and the operating state (b) of the shock absorber 51 in which the second arm portion 532 (concave portion 534) of the movable member 53 is displaced downward with respect to the extension portion 522 (concave portion 524) of the base member 52 and the spring 54 is compressed. The displacement 54s of the spring 54 corresponds to the displacement stroke 53s of the axle 5a in FIG. 6.

[0032] The buffer device 51 has an initial displacement even in a stationary state due to the weight of the small electric vehicle 1 and the occupants, and will further displace in response to an impact acting on the front wheel 5 due to road surface irregularities or the like from that state. Therefore, even when the front wheel 5 passes over road surface irregularities or the like and the spring 54 elastically recovers, the initial displacement usually remains. If the initial displacement is released and it returns to the inoperative position as shown in Fig. 7(a), the spring 54 can elastically deform between the lower edge of the movable member recess 534 and the upper edge of the base member recess 524 with respect to the upward swing of the second arm portion 532 of the movable member 53. Therefore, it also has a function of mitigating the impact when the movable member 53 returns to the inoperative position.

[0033] Also, as shown in Fig. 7, the spring 54 is accommodated in a hollow portion (recesses 524, 534) defined by the thicknesses of the base member 52 (extension portion 522) and the movable member 53 (second arm portion 532) that are in sliding contact at the sliding contact surface 52b. With this configuration, there is an advantage that the width as the buffer device 51 can be kept small.

[0034] Furthermore, in a state where the spring 54 is accommodated in the hollow portion (recesses 524, 534), the openings of the recesses 524, 534 are closed by the cover members 525, 535, so that the spring 54 is positioned in the hollow portion (recesses 524, 534). Therefore, a separate mounting or positioning structure is not required. Also, since the spring 54 has a structure that is sealed in the hollow portion (recesses 524, 534), there is an advantage that it can prevent the intrusion of dust and water droplets from the outside.

[0035] The buffer device 51 of the above embodiment shows the case where one set of recesses 524, 534 is provided in the base member 52 and the movable member 53, but it can also be configured such that a plurality of sets of recesses 524, 534 are provided in the base member 52 and the movable member 53, and the spring 54 is accommodated in each of them.

[0036] For example, the buffer device 91 of the embodiment shown in FIG. 8 includes four springs 94 equally angularly arranged at 90-degree intervals in the circumferential direction 94a (direction intersecting the radial direction) centered on the swing axis 93a of the hub portion 932 of the movable member 93 (swing arm 931) that supports the axle 5a, and four recesses (not shown) for accommodating them. The base member (not shown) also includes four recesses. In this example, the four springs 94 are arranged along the common circumferential direction 94a, but they may be arranged at different radial positions.

[0037] Note that it can also be configured to include three springs equally angularly arranged at 120-degree intervals and corresponding three sets of recesses. Similarly, it can also be configured to include two springs equally angularly arranged at 180-degree intervals and corresponding two sets of recesses. By arranging the springs equally angularly, there is an advantage that the lateral stress associated with the elastic deformation of the springs and the stress in the adjacent direction between the movable member and the base member are offset.

[0038] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various modifications and changes are possible based on the technical idea of the present invention.

Explanation of Reference Numerals

[0039] 1 Small electric vehicle 2 Vehicle body 3 Rear handle (walking assist vehicle mode operation unit) 4 Rear wheel (drive wheel) 5 Front wheel (driven wheel, swivel wheel) 6 Loading portion 7 Seat 8 Riding mode operation unit 21 Moving base 22 Upper frame 24 Rear side base 25 Front side base 40 Motor unit 51, 91 Buffer device 52 Base member 52b Sliding contact surface 53, 93 Movable member 54,94 Spring 524 Concave portion (base member side concave portion) 534 Concave portion (movable member side concave portion)

Claims

1. A shock absorber for a wheel of a small electric vehicle, a base member fixed to the vehicle body, a movable member having an axle supported or fixed thereto, slidably contacting the base member via a sliding contact surface perpendicular to the axle, and being connected so as to be swingable about an axis parallel to the axle, and a spring disposed between the base member and the movable member so as to be elastically compressed by the swinging of the movable member, characterized in that, the base member and the movable member have recesses facing each other and including a common region on the sliding contact surface, and the spring is accommodated in a hollow portion defined by the recess on the base member side and the recess on the movable member side such that a direction intersecting the radial direction centered on the axis is the elastic compression direction. The shock absorber.

2. The shock absorber according to claim 1, wherein one end of the spring is supported on the inner surface of the recess on the base member side via a plate, and the other end of the spring is supported on the inner surface of the recess on the movable member side via a plate.

3. The shock absorber according to claim 1, wherein the recess on the base member side and the recess on the movable member side have an inner peripheral side surface extending in an arc shape centered on the axis along the axis side of the spring, and an outer peripheral side surface extending in an arc shape centered on the axis along the side opposite to the axis of the spring, and the lateral displacement of the spring is restricted by the inner peripheral side surface and the outer peripheral side surface.

4. The shock absorber according to claim 1, wherein the recess on the base member side and / or the recess on the movable member side is defined by an opening penetrating the base member and / or the movable member, and a cover member detachably attached to the base member and / or the movable member so as to close the opening.

5. The base member and the movable member are each formed of a plate material having a substantially uniform thickness, and the base member is fixed to the vehicle body via a spacer. The shock absorber according to claim 1, characterized in that.

6. The base member and the movable member have a plurality of sets of concave portions facing each other and including a common region on the sliding contact surface, and the springs are respectively accommodated in the hollow portions defined by the sets of concave portions. The shock absorber according to claim 1, characterized in that.

7. The shock absorber according to claims 1 to 6 is provided on the left and right front wheels each composed of an omnidirectional moving wheel. A small electric vehicle configured to be able to perform steering and driving by individually driving the left and right drive wheels by left and right motors.

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