JP5978446B2 - Rear suspension structure for public road commuter - Google Patents

Description

  The present invention relates to a simple and economical rear suspension structure for a public road traveling commuter suitable for a small public road traveling commuter such as a two-seater electric city commuter.

  As for the electric commuter for running on public roads, a light vehicle standard is already on the market. However, the electric commuter is also promising as a smaller two-seater city commuter, and standards are being developed for that purpose. The core of the standard is the city commuter, so it is a two-seater ultra-compact car with a small road occupying area, and the maximum speed is limited to 60km to prohibit highway driving. For example, the impact strength in the event of a collision is greatly reduced.

  As one of the precedents of such a small two-seater electric commuter, there is a golf car used for moving a golfer and transporting a golf equipment in a golf course, and it is often preferable to divert the structure. For example, with respect to the rear suspension, those used in Yamaha Motor's golf car G31-EP and the like can be referred to (Non-Patent Document 1). The center of the rear suspension is a U-shaped swing arm made up of a combination of a horizontal beam and two vertical beams extending from both ends of the rear suspension to the rear of the vehicle body.

  The U-shaped swing arm is connected to an axle that connects the rear wheels on both sides. In addition, the central part of the horizontal beam is connected to the front body frame via an elastic material such as rubber so that it can tilt in all directions, and the rear part of the vertical beam on both sides is composed of a combination of a spring and a damper. It is connected to the upper body frame via As a result, the U-shaped swing arm swings up and down with the rubber bush portion, which is a connecting portion with the frame, as a fulcrum, and also rolls left and right, whereby the rear wheels on both sides can be moved up and down independently.

  In addition, this U-shaped swing arm is suitable for mounting a drive system such as a motor in terms of position and shape, and is connected to the vehicle body side via an elastic member, so that vibration of the drive system is reduced. There is also an advantage that it is difficult to be transmitted to the car body side. When the drive system is mounted, the drive shaft of the drive system also has an advantage that it can also serve as an axle that connects the rear wheels on both sides, and the drive shaft that also serves as the axle is connected and fixed to the U-shaped swing arm.

  On the other hand, the U-shaped swing arm has a drawback that it tilts in the vehicle width direction (lateral direction) with the connecting portion at the center of the front as a fulcrum. This causes the rear wheels to steer on both sides. In order to prevent this rear wheel steer, in the above-described golf car G31-EP made by Yamaha Motor, the lateral direction of the U-shaped swing arm is set by an inclined link rod inclined in a plane perpendicular to the vehicle full length direction (vehicle length direction). Positioning is performed. That is, one end portion (downstream end portion) of the inclined link rod is connected to the vertical beam on one side, and the other end portion (upstream end portion) is connected to the frame on the other side. While allowing the arm to move up and down, it prevents lateral movement.

  Such a rear suspension structure is suitable for a two-seater small electric city commuter with a small number of parts. However, when the U-shaped swing arm swings up and down as the rear wheel moves up and down, When the connecting portion side with the U-shaped swing arm moves circularly around the connecting portion side with the frame, the U-shaped swing arm tilts in the lateral direction (vehicle width direction) and tilts the rear wheels on both sides. This tilting in the vehicle width direction is called bump steer, and there is no problem for special vehicles that do not travel on public roads such as golf cars whose maximum speed is limited to 20 km / h or less. This causes a decrease in steering performance, and cannot be ignored.

  This problem occurs without exception in a public road traveling commuter regardless of whether the drive system is an electric motor system or an internal combustion engine system.

http://www.yamaha-motor.co.jp/parts-search/

  An object of the present invention is to provide a rear suspension structure for a public road traveling commuter capable of reducing bump steer as much as possible while having a simple structure.

In order to achieve the above object, the suspension structure for a public road traveling commuter according to the present invention comprises a combination of a horizontal beam and two vertical beams extending from both ends of the vehicle to the rear of the vehicle body. The U-shaped swing arm is connected to the side so that it can tilt in all directions, and the axles that connect the rear wheels on both sides to the vertical beams on both sides, and parallel to the vertical beams on both sides of the U-type swing arm disposed, so as each to swing in the vertical direction following the longitudinal beams on both sides, each of the front end, is supported by a vehicle body on the center line in the vertical direction of the swing motion of the U-shaped swing arm, respectively A buffer disposed between the equal-length link rods on both sides, the rear end of which is connected to the vertical beams on both sides, and the vehicle body side to suppress the vertical swing movement of the U-shaped swing arm. It is and a knit.

In the rear suspension structure for a public road commuter of the present invention, it is important that the equal-length link rods are arranged in parallel to the vertical beams on both sides of the U-shaped swing arm, and the equal-length link rods on both sides follow the vertical beams on both sides. Swinging in the vertical direction, and for that purpose, the front ends of the equal-length link rods on both sides are pivotally supported on the vehicle body side on the center line of the vertical swing motion of the U-shaped swing arm, in other words The tilting center of the U-shaped swing arm is located on the center line of the vertical swing motion of the equal-length link rods on both sides, and the center line of the vertical swing motion of each of the U-shaped swing arm and the equal-length link rods on both sides Is a match.

  As a result, in the rear suspension structure for a public road commuter of the present invention, the equal-length link rods on both sides are not affected by the vertical beam on both sides of the U-shaped swing arm and the vertical swing motion of the U-type swing arm. As a result, the U-shaped swing arm is prevented from tilting in the vehicle width direction and positioned with high accuracy, thereby effectively suppressing the occurrence of bump steer.

  If the rear suspension structure is designed so that the equal-length link rods on both sides are in a horizontal posture with both rear wheels under normal load, the vertical swing center line of the equal-length link rods on both sides The distance change from the support point for supporting the vertical beam on both sides of the U-shaped swing arm to the side where the rear wheel bumps in the direction in which the buffer unit contracts and the side where the rear wheel bumps in the direction in which the buffer unit extends are equal. Therefore, the tilting displacement of the U-shaped swing arm in the vehicle width direction, and the effect of preventing the rear wheel steering due to this are particularly high.

  Similarly, it is desirable that the equal-length link rods on both sides are longer from the viewpoint of suppressing the change in distance and suppressing the tilt displacement in the vehicle width direction of the U-shaped swing arm and the resulting rear wheel steer.

  In the rear suspension structure for a public road traveling commuter according to the present invention, it is rational and preferable that the drive system is mounted on the U-shaped swing arm and that the drive shaft in the drive system also serves as the axle connecting the rear wheels on both sides.

  The U-shaped swing arm is configured to be able to turn in all directions by interposing an elastic member at the connecting part with the vehicle body side, so that vibrations on the rear suspension side can be prevented from being transmitted to the vehicle body side. preferable.

In addition, the equal-length link rods on both sides can rotate around the straight line parallel to the center line of the vertical swing motion of the U-shaped swing arm, with the rear ends of the rear ends on the vertical beams on both sides of the U-shaped swing arm. Is pivotally supported . This arrangement serves to ensure smooth swinging operation of the U-shaped swing arm is effective in enhancing the bump steer preventing effect and prevents any other extra operations.

The rear suspension structure for a public road traveling commuter according to the present invention has a simple structure because a U-shaped swing arm connected to the vehicle body side so as to be tiltable in all directions is a main component. The displacement in the vehicle width direction, which is a problem with the U-shaped swing arm, is prevented by the equal-length link rods on both sides of the U-shaped swing arm that swings up and down following the vertical beams on both sides, making the structure complicated Bump steer can be prevented without accompanying. In addition, the equal-length link rods on both sides are arranged in parallel with the vertical beams on both sides of the U-shaped swing arm and are integrally disposed therewith, so that substantially no extra space is required. Compared to the inclined link rods arranged at, the space at the rear of the vehicle body is advantageous.

FIG. 2 is a schematic perspective view showing an example of use of a rear suspension structure for a public road traveling commuter showing an embodiment of the present invention, and is a configuration diagram of a frame portion of a two-seater ultra-small electric city commuter using the rear suspension structure. . It is a top view which shows the detail of the rear suspension structure in the city commuter. It is a side surface which shows the detail of the rear suspension structure in the same city commuter. It is a rear view which shows the detail of the rear suspension structure in the same city commuter. It is a rear view which shows operation | movement of the rear suspension structure. It is a rear view which shows another operation | movement of the rear suspension structure.

  Embodiments of the present invention will be described below.

  The rear suspension structure for a public road traveling commuter of this embodiment is used in a two-seater ultra-small electric city commuter. The micro electric city commuter has a chassis with a frame structure as shown in FIG. The frame 10 includes a central portion 10A on which a driver is mounted and a battery or the like is mounted, a front portion 10B that is in front of the central portion 10A and mainly supports the front wheels 20 and 20 on both sides, and a rear portion of the central portion 10A. The rear portion 10C mainly supports the rear wheels 30 and 30.

  The front wheels 20, 20 on both sides are supported by the front portion 10B of the frame 10 so as to be steerable by an independent suspension type front suspension mechanism such as a double wishbone structure (not shown). As shown in FIGS. 2 to 4, the rear suspension mechanism 40 that supports the rear wheels 30, 30 on the rear portion 10C of the frame 10 is a U-shaped swing arm that is horizontally disposed in the rear portion 10C with a transverse beam in front. 41 is a composite structure in which the equal-length link rods 42 and 42 on both sides arranged along the vertical beam are provided outside the vertical beam on both sides of the U-shaped swing arm 41.

  The rear suspension mechanism 40 will be described in more detail. The rear portion 10C of the frame 10 that supports the rear suspension mechanism 40 is here a first horizontal member that connects the rear end portions of the first vertical members 11, 11 on both sides extending in the vehicle length direction. 12, second vertical members 14, 14 connected to a position higher than the first vertical members 11, 11 via inclined portions 13, 13 with respect to the rear end portions of the first vertical members 11, 11, It consists of the 2nd horizontal member 15 which connects the rear-end parts of the vertical members 14 and 14. FIG.

The U-shaped swing arm 41 in the rear suspension mechanism 40 is a processed product of a metal material disposed behind the first lateral member 12, and includes a lateral beam 41a in the vehicle width direction and a vehicle length direction from both ends of the lateral beam 41a. It consists of a combination of parallel longitudinal beams 41b, 41b on both sides extending rearward. The central part of the horizontal beam 41a is connected to the first horizontal member 12 of the frame 10 via an elastic member 48 made of rubber, so that the U-shaped swing arm 41 has all directions around the U-shaped center line, That is, the U-shaped swing arm 41 can be tilted in all directions around the center line . Reference numeral 16 denotes a swing arm coupling bracket that also serves as an accommodating and holding portion of the elastic member 48 attached to the central portion of the first lateral member 12.

  The equal-length link rods 42, 42 on both sides are processed metal materials similar to those of the U-shaped swing arm 41, and are basically parallel to the outside of the vertical beams 41b, 41b on both sides of the U-type swing arm 41. It is a linear member, and strictly speaking, the vicinity of the front end is curved along the curved connection portion between the horizontal beam 41a and the vertical beams 41b and 41b in the U-shaped swing arm 41 so that the front end is displaced inward. ing.

  The front end portions of the equal-length link rods 42, 42 are connected to the first vertical members 11, 11 of the frame 10, the inclined portions 13, 13, and the brackets 17, 17 that also serve as reinforcing members provided inside the connection portion, Directional support shafts 43 and 43 are rotatably connected. The centers of the support shafts 43, 43 on both sides are located on a straight line in the vehicle width direction passing through the tilt center O of the U-shaped swing arm 41, whereby the isometric link rods 42, 42 are connected to the U-shaped swing arm 41. Are supported on the center line C of the vertical swing motion.

  That is, the tilt center O of the U-shaped swing arm 41 is positioned on the center line C of the vertical swing motion of the equal-length link rods 42, 42, and the U-shaped swing arm 41 and the equal-length link rods 42, 42 The center lines of the vertical swing motions of these are coincident.

  The rear end portions of the equal-length link rods 42, 42 are connected to the vicinity of the rear portions of the vertical beams 41b, 41b in the U-shaped swing arm 41 so as to be rotatable from the outside by support shafts 44, 44 in the vehicle width direction.

  The rear ends of the vertical beams 41b and 41b in the U-shaped swing arm 41 are connected to the upper second vertical members 14 and 14 via buffer units 45 and 45 that combine a coil spring and a damper. Both end portions of each buffer unit 45 are rotatably connected to each member by support shafts 46 and 47 in the vehicle width direction.

  The drive system 50 has a rigid structure in which drive shafts 53 and 53 extending from both sides of the electric motor 51, the differential gear 52, and the differential gear 52 are integrated, and the drive shafts 53 and 53 on both sides are connected to the differential gear 52 therebetween. In addition, a rigid axle 31 in the vehicle width direction that connects the rear wheels 30, 30 on both sides is configured. The axle 31 is connected to the vicinity of the rear portions of the vertical beams 41b and 41b in the U-shaped swing arm 41 from above by a mounting bracket (not shown).

  Next, the operation and function of the rear suspension structure of the present embodiment will be described in detail with reference to FIGS.

  When normal loads are applied evenly to the rear wheels 30 and 30, as shown in FIG. 4, the rear wheels 30 and 30 on both sides and the axle 31 connecting them are symmetrical with respect to the center of the vehicle body. It is in a regular position and the axle 31 is horizontal.

  When the rear wheels 30, 30 on both sides are evenly bumped from this state, the shock-absorbing units 45, 45 on both sides of the rear suspension mechanism 40 are evenly contracted, and the U-shaped swing arm 41 has the equal-length link rods 42, 42 and swings upward about the same center line C on the front end side. Since both swing center lines C are the same, the U-shaped swing arm 41 is stretched evenly on both sides in the vehicle length direction by the equal-length link rods 42, 42 on both sides, and is supported by pulling in the vehicle width direction. Since tilting does not occur, bump steer is not generated on the rear wheels 30, 30 on both sides.

  Similarly, when the rear wheels 30, 30 are evenly displaced toward the side where the buffer units 45, 45 on both sides extend, the U-shaped swing arm 41 does not tilt in the vehicle width direction. Does not generate bump steer.

  When the rear wheel 30 on one side bumps in the direction in which one of the buffer units 45, 45 on both sides contracts, the rear wheels 30, 30 on both sides are connected by a rigid axle 31 as shown in FIGS. Therefore, the U-shaped link rod 41 tilts sideways, that is, rolls. As a result, the isometric link rod 42 swings upward on the side where the rear wheel 30 is bumped.

  When the equal-length link rod 42 performs such a swing operation, as shown in FIGS. 2 and 3, the support point S of the equal-length link rod 42 with respect to the vertical beam 41 b of the U-shaped swing arm 41, that is, the support shaft 44. The center moves circularly on an arc having a radius R, and the distance L from the swing center line C to the support point S changes. However, the change is very small, and the closer the isometric link rod 42 is to the horizontal, Further, since it becomes smaller as the length becomes longer, the tilting of the U-shaped swing arm 41 in the vehicle width direction and the steer amount of the rear wheels 30 and 30 due to this tilting are negligibly small.

  When the rear wheel 30 on one side bumps in the direction in which one of the buffer units 45, 45 on both sides contracts, the rear wheel 30 tends to be displaced in the direction in which the buffer unit 45 extends on the opposite side. In that case, the equal-length link rods 42 on both sides swing in the opposite direction, and the distance L from the swing center line C to the support point S changes individually on both sides, but each change is very slight. As a result, the U-shaped swing arm 41 is tilted in the vehicle width direction, and the steer amount of the rear wheels 30, 30 on both sides is also extremely small.

  If it is designed so that the equal-length link rods 42, 42 on both sides are horizontal while the rear wheels 30, 30 are subjected to a normal load, as described above, from the swing center line C to the support point S, Not only is the distance L essentially suppressed, but also the position change of the support point S on the side where the rear wheel 30 bumps in the direction in which the buffer unit 45 contracts and the rear wheel 30 in the direction in which the buffer unit 45 extends. Since the position change of the support point S on the bumped side becomes equal and cancels out, the U-shaped swing arm 41 is tilted in the vehicle width direction and the rear wheels 30 and 30 are not steered at all.

  From this point of view, the equal-length link rods 42, 42 on both sides are preferably designed so that the rear wheels 30, 30 are in a horizontal posture or a posture close to this when the normal load is applied.

  The U-shaped swing arm 41 is connected to the first horizontal member 12 of the frame 10 via an elastic member 48 made of rubber so as to be tiltable in all directions. Although connection by a ball joint or the like is possible, the connection by the elastic member 48 is shock vibration from the rear wheels 30 and 30 and the drive system 50 to the frame 10 via the U-shaped swing arm 41 as compared with the connection by a ball joint or the like. There is an advantage that can suppress the transmission.

  In the rear suspension structure of the above embodiment, the drive system 50 is an electric system using the electric motor 51. However, a system using an internal combustion engine such as a gasoline engine or a diesel engine is also effective.

  The material of the constituent members in the rear suspension structure is a round pipe in the illustrated example, but it may be a square pipe or a mold material such as an I-shaped material, regardless of the type. The material of the constituent member is generally a metal material such as steel or aluminum, but is not limited thereto, and may be a resin material such as FRP or carbon fiber, and the type thereof is not limited.

  In the above embodiment, the rear suspension structure is used in a two-seater ultra-small electric city commuter, but it goes without saying that it can be applied to other public road traveling commuters.

DESCRIPTION OF SYMBOLS 10 Frame 10A Center part 10B Front part 10C Rear part 11 1st vertical member 12 1st horizontal member 13 Inclination part 14 2nd vertical member 15 2nd horizontal member 16, 17 Bracket 20 Front wheel 30 Rear wheel 31 Axle 40 Rear suspension mechanism 41 U Type swing arm 41a horizontal beam 41b vertical beam 42 isometric link rod 43, 44, 46, 47 support shaft 45 buffer unit 48 elastic member 50 drive system 51 motor 52 differential gear 53 drive shaft C U type swing arm and equal length link rod Swing centerline in the vertical direction of the center O The tilting center point of the U-type swing arm S The support point of the equal-length link rod with respect to the vertical beam of the U-type swing arm R The turning radius of the support point S accompanying the swing motion of the equal-length link rod L From swing center line S of long link rod Distance to the lifting point S

Claims (4)

The combination of the transverse beam and the two longitudinal beams extending from the opposite ends to the rear of the vehicle body makes it U-shaped, and the central part of the transverse beam is connected to the vehicle body side so that it can tilt in all directions around the U-shaped center line. And a U-shaped swing arm to which an axle for connecting the rear wheels on both sides to the vertical beams on both sides is connected;
The U-shaped swing arm is arranged in parallel with the vertical beams on both sides and swings in the vertical direction following the vertical beams on both sides. Equal-length link rods on both sides that are pivotally supported on the vehicle body side on the center line and each rear end portion is connected to the vertical beams on both sides;
A shock absorber unit disposed between the U-shaped swing arm and the vehicle body to suppress the vertical swing motion of the U-shaped swing arm;
Since the tilting center of the U-shaped swing arm is positioned on the center line of the vertical swing motion of the equal-length link rods on both sides, the vertical swing motion of each of the U-shaped swing arm and the equal-length link rods on both sides The centerlines match,
In addition, the equal-length link rods on both sides can rotate about the straight line parallel to the vertical line of the U-shaped swing arm in the vertical direction on the both sides of the U-shaped swing arm. Rear suspension structure for an electric commuter that is pivotally supported. The rear suspension structure for an electric commuter according to claim 1,
A rear suspension structure for an electric commuter that is designed so that the equal-length link rods on both sides assume a horizontal posture or a posture close to it while the rear wheels on both sides receive a normal load. In the rear suspension structure for an electric commuter according to claim 1 or 2,
A rear suspension structure for an electric commuter in which a drive system is mounted on a U-shaped swing arm, and a drive shaft in the drive system also serves as an axle connecting the rear wheels on both sides. In the rear suspension structure for an electric commuter according to any one of claims 1 to 3,
The U-shaped swing arm is a rear suspension structure for an electric commuter that can be tilted in all directions around its U-shaped center line by interposing an elastic member at a connecting portion with the vehicle body side.

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