JP3385634B2 - Crawler equipped vehicle suspension structure - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension structure of a crawler-equipped vehicle that travels on snow by driving a rear crawler supported by a rear end of a rear swing arm. It relates to something that makes the stroke smoother. 2. Description of the Related Art Conventionally, there is a small snowmobile in which a front wheel or a sled is attached to a front fork, a crawler (crawler belt) is attached to a rear portion, and a crawler is driven by an engine so that the vehicle can run on snow (Japanese Patent Laid-Open Publication No. HEI 9-102). 2-262488). However, there has been no conventional small snowmobile capable of coping with various road surfaces such as a fresh snow surface, a hard snow surface which has been hardened, or a snow-free road surface. On the other hand, the applicant has already proposed a small snowmobile capable of coping with various road surfaces and improving running performance on snow.
2329 (unknown). FIG. 5 shows the configuration of this small snowmobile. In FIG. 5, an engine a drives a rear chain d via a continuously variable belt transmission b and a gear reducer c, and further drives a driving sprocket e. The crawler f is driven by the driving force of the driving sprocket e, pushing the snow surface backward, and moving the small snowmobile forward. The crawler f is wound around the driving sprocket e and the free sprocket g. Further, the crawler f is expanded and expanded downward along idlers h1 to h4 provided on the crawler frame h together with the respective sprockets e and g, and extends long in the front-rear direction of the vehicle body to near the rear side of the front fork i. Have been banished. The crawler frame h has a swing arm j
Is axially supported coaxially with the drive sprocket e.
The other end of the swing arm j is supported by a pivot shaft j1 in the vicinity of the output sprocket of the gear reducer c behind the vehicle lower frame k. Also, swing arm j
Is connected to one end of each of the upper and lower suspensions l and m. The other end (upper eye) of the upper suspension 1 is pivotally supported at the lower part of the frame (rear frame) k, and the other end (under eye) of the lower suspension m is pivotally supported at the upper side of the crawler frame h. The other configuration is shown in the above-mentioned application, and the description is omitted. The present inventor has made various runs on this small snowmobile. At this time, the small snowmobile has a front wheel shared load of 40 to 45% of a normal motorcycle shared load.
If it is not lighter, the front wheels will easily sink into the snow, and sometimes it will not be possible to achieve the desired driving performance and handling performance. In order to eliminate such inconvenience, as shown in FIG. 5, the position of the step is set to be slightly less than the center position where the crawler f touches the ground on a hard road surface from the center position p1 of the lower frame according to a general motorcycle. It has been found that it is optimal to set the position p2 to the front and a position slightly behind the pivot axis j1 of the swing arm j. [0005] However, in the small snowmobile (vehicle with a crawler), the chain (rear chain) must be disposed outside the crawler, and the front end of the chain must be disposed. Since it extends forward from the steps, the width between both steps becomes too wide. In this case, there is a problem that the driver's legs become too wide and the bank angle tends to decrease. SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and has a crawler-equipped vehicle capable of displacing a step backward without increasing the step width even when the crawler is wide. An object of the present invention is to provide a suspension structure. According to the present invention, a crawler is wound around a crawler frame extending below a vehicle body in a front-rear direction and having a free sprocket and a driving sprocket rotatably provided at front and rear ends. In a vehicle provided with a rear crawler in which a predetermined lower portion of a crawler is curved downward by a lower rolling wheel rotatably provided on the crawler frame, the rear crawler has a front end pivot shaft attached to the body frame. The rear end of the crawler frame is rotatably supported at the rear end of a swing arm, which is rotatably supported as a fulcrum and vertically extended and extends rearward and has a cushion between itself and the body frame, while the crawler frame is rotatably supported. The front end is supported by a suspension provided between the vehicle body frame and the rear crawler. A drive sprocket is provided at the rear end, and is driven by a drive chain and a transmission chain arranged along the swing arm, and the pivot shaft of the rear swing arm is
Behind the step, and located substantially above the crawler ground contact surface on a flat surface, the crawler frame suspension is disposed forward of the pivot axis,
This object is achieved by fixing the upper mounting end of the suspension to a body frame other than the rear swing arm. In the present invention, the crawler frame suspension may be disposed forward of the step. Further, in the present invention, the tangent angle of the rear end shaft of the swing arm and the tangent angle of the lower portion of the rear crawler frame suspension attached to the frame between the states where the suspension of the rear swing arm is most extended to the most compressed state are positive and negative. May remain the same, and the magnitude relationship of the values may not be reversed. According to the present invention, the pivot shaft of the rear swing arm is located behind the step and substantially above the crawler contact surface on a flat surface, and the crawler frame suspension is moved from the pivot shaft. Since the suspension is located at the front and the upper mounting end of the suspension is fixed to the body frame other than the rear swing arm, even if the crawler width is wide, the steps are shifted backward without increasing the step width, so that a large lean angle can be obtained. At the same time, driving performance in fresh snow is improved. Further, in the present invention, if the crawler frame suspension is disposed in front of the step, the contact surface of the crawler strokes according to a change in the road terrain, for example, along the change in the terrain, so that the riding comfort and running performance are improved. The performance is improved. Also, the tangent angle of the rear end shaft of the swing arm and the tangent angle of the lower part of the suspension for the rear crawler frame attached to the frame between the most extended and most compressed states of the suspension of the rear swing arm remain the same. In addition, if the magnitude relationship is not reversed, a change in load of the suspension does not have a dead point, so that a smooth stroke change occurs and riding comfort is improved. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a small snowmobile according to a first embodiment of a crawler-equipped vehicle of the present invention. FIG. 2 shows a pivot shaft 30 of the rear swing arm 18 of the small snowmobile.
FIG. FIG. 3 and FIG. 4 are explanatory diagrams of the buffer operation by the suspensions 25 and 26. FIG. In the configuration of FIG. 1, a seat 2 is provided on an upper portion of a vehicle body 1, and a bar handle 4 is connected to an upper end of a front fork 3. The front fork 3 is of a bottom link type, in which the suspension 5 is expanded and contracted to swing the link 6 to form a cushion for the front wheel 7. The engine 8 drives a front chain 11 via a continuously variable belt transmission 9 and a gear reducer 10 to drive a constant velocity universal joint 12. And, furthermore, a uniform joint 12
From primary chain 13, idler 14, secondary chain 15
The front wheel 7 is driven via the. On the other hand, the engine 8 is connected to the transmission chain 18 and the first drive sprocket 31 via the continuously variable belt transmission 16 and the gear reducer 17.
The drive chain 32 is driven, and the crawler drive sprocket 19 is driven. The sprocket 19 has a crawler 20
Are engaged with each other, so that the crawler 20
Driven by The engine 8 is surrounded and supported by a lower frame 33. Behind the lower frame 33 and below the rear frame 34, an arm frame 35 for rotatably supporting the drive sprocket 31 is provided. It is provided fixed to the frames 33 and 34. As shown in FIG. 2, the arm frame 35 is configured to be narrower than the lower frame 33. The step p2 is provided slightly below the mounting position of the arm frame 35 at the lower rear part of the lower frame 33. A pivot shaft 30 on the front end side of a swing arm 36 is provided coaxially with the rear end of the arm frame 35, that is, the drive sprocket 31, and the swing arm 36 has the rear end pivotally supporting the drive sprocket 19. . The swing arm 36 moves up and down about the pivot shaft 30 in accordance with the up and down movement of the crawler 20. As shown in FIG. 2, a second drive sprocket 17a is fixed to the output shaft of the gear reducer 17 in the rotation direction. A driven gear 31 a fixed to the first drive sprocket 31 in the rotation direction and a turning side of the brake unit 37 are rotatably supported by the pivot shaft 30. In this case, the fixed side of the brake unit 37 is fixed to the arm frame 35 in the axial direction. Further, the arm frame 35 extends rearward from the lower frame 33 narrower than the width thereof, narrower than the width of the rear swing arm 36, and reaches the space between the arm 36 and the brake unit 37 to support the pivot shaft 30. ing. Further, a transmission chain 18 is arranged and bridged between the second drive sprocket 17a and the driven gear 31a inside the lower frame 33. Drive sprocket 31 and drive sprocket 1
9, the drive chain 32 is arranged inside the swing arm 36 and bridged. Therefore, the driving force of the engine 8 is transmitted to the second drive sprocket 17a → the driven gear 31a → the drive sprocket 31 → the drive sprocket 19 → the crawler 20. The crawler 20 is a crawler belt provided corresponding to the rear wheel portion. The crawler 20 is wound around the free sprocket 22 and the driving sprocket 19 to mesh therewith. Crawler 20
Are the free sprocket 22, the driving sprocket 19, and the idler 2 attached to the crawler frame 24.
The front fork 3 is extended long in the front-rear direction of the vehicle body 1 to near the rear side of the front fork 3. The crawler 20 is driven to rotate by a driving sprocket 19 disposed at the rear end of the crawler 20 and a free sprocket 22 disposed at the front end of the crawler 20. The idlers 27 a to 27 d are of a so-called center guiding type, for example, for guiding a projection provided on the inner peripheral side of the crawler 20. Of the idlers 27a to 27d, idler 2
7c and 27d are rollers that contact the ground via the crawler 20 when traveling on a flat and hard road surface, for example, a paved road,
This is the roller that receives the impact load first. Among the idlers 27a to 27d, the idlers 27a and 27b are rollers that are not grounded via the crawler 20 when traveling on a pavement. Therefore, since the idlers 27c and 27d are the lowest, the crawler 20 is expanded in a curved state so that the crawler 20 is swelled downward and the rearward of the center is the lowest. The crawler 20 is formed by embedding a core metal (not shown) in a lateral direction at predetermined intervals, and is formed of rubber. The inner peripheral side of the crawler 20 is provided with a row of locking holes at the center in the width direction for engaging the teeth formed on the free sprocket 22 and the driving sprocket 19 to rotate the crawler 20. Each suspension 25, 26 is provided between the crawler frame 24 and the vehicle body 1 to reduce impact. That is, in the crawler frame 24,
The lower eye of one end of the suspension 25 is connected to the lower eye of the lower frame 33. Further, the under eye side of the suspension 26 is mounted on the upper side of the swing arm 36 via a mounting member 36a, and the upper eye side of the other end of the suspension 26 is mounted on the lower portion of the rear frame 34 at a slightly lower rear portion. . Therefore, the impact load applied from the crawler 20 is applied to the crawler frame 24, and is transmitted to the vehicle body 1 via the suspension 25 at the front portion of the crawler frame 24. In the rear part, the power is transmitted to the vehicle body 1 via the swing arm 36 and the suspension 26. Thus, the suspensions 25, 26
The impact load described above is reduced by the expansion and contraction of. In the present embodiment, as shown in FIGS. 1 to 3, the drive sprocket 31 of the chain 32 for driving the crawler 20 is shifted rearward of the step p2.
Since the transmission chain 18 is arranged inside the lower frame 33, the width between the steps p2 on both sides of the vehicle body is set to the width of the crawler 20 (the drive chain 32 passing outside the crawler 20).
Regardless of the width). Therefore, it is possible to prevent the legs of the driver who steps in step p2 from becoming divergent, and to increase the bank angle of the vehicle body, it is easy to make the vehicle lean during traveling. Also, if the pivot axis of the swing arm is provided at the position indicated by the symbol j in the figure, the step width becomes wider as the crawler width is widened as in step p2a. Such a case does not occur because the line is provided as shown by the solid line. Also, if the suspension of the crawler frame is provided as shown by reference numeral m in the figure, the suspension may be in the way of getting on the vehicle. However, in this embodiment, the suspension is provided at the front. Nothing happens. Here, the location where the pivot shaft 31 and the lower suspension 25 are arranged and attached will be described. As shown in FIG. 3, when the pivot shaft 31 is provided at the rear of the lower frame 33, the pivot shaft is located near a ground contact surface of the crawler 20 on a hard road surface. Therefore, if the lower suspension 25 is disposed between the crawler frame 24 and the swing arm 36 as shown by the reference numeral 25a in FIG. 3 (according to the small snowmobile in FIG. 5), the upper suspension 26 The swing arm 36 may not perform its function (the function of causing the crawler frame 24 to stroke in parallel with the road surface). Therefore, the arrangement of the suspension 25 is not at the rear of step p2 but at the front of step p2. In the embodiment, the position is indicated by reference numeral 25 instead of the position indicated by reference numeral 25a. As a result, the contact surface of the crawler 20 changes according to the change in road surface topography.
For example, since the user strokes along the terrain, riding comfort and running performance are improved. Further, in the crawler frame suspension 25, the tangent angle β of the lower mounting portion (under eye) of the suspension 25 from the most extended to the most compressed state.
a to βb, and the tangent angle αa to αb of the swing arm 36 when the suspension 26 is most extended to most compressed.
Think about In the process of changing these tangent angles from βa to βb and from αa to αb, the sign of these angles is reversed, or the magnitude relationship between one value and the other value changes in the middle (the magnitude relationship between the values is reversed). And a dead point is formed in the cushion stroke of the suspension 25. For example,
When the suspension 25 is set to the alignment as shown by 25b in FIG. 3, the cushion stroke of the suspension 25 has a dead point as shown by the broken line in FIG. 4, and the stroke may be difficult. Therefore, in order to prevent such a state from occurring, the tangent angle αa is set to α
b and the tangent angles βa to βb have opposite signs,
By setting the suspension 25 in such an alignment that the magnitude relationship between these values does not reverse, there is no dead point in the stroke change of the suspension 25 as shown by the solid line in FIG. Become. According to the present invention, the present invention is not limited to the configuration of the above-described embodiment, but may take various forms within the scope of the present invention. For example, in the above-described embodiment, the upper suspension 26 is disposed on the lower frame 33 and the rear frame 34 via the arm frame. However, this arm frame can be integrated with the body frame. . According to the present invention, even if the crawler has a large width, the steps are shifted backward without increasing the step width, so that a large lean angle can be obtained and the running performance in fresh snow is improved. Excellent effects can be obtained. Further, in the present invention, if the crawler frame suspension is disposed ahead of the step, the contact surface of the crawler strokes along the road terrain according to the change of the road terrain, so that the riding comfort and running performance are improved. In addition, the tangent angle of the rear end shaft of the swing arm and the tangent angle of the lower part of the rear crawler frame suspension attached to the frame between the states where the suspension of the rear swing arm is most extended to the most compressed state remain the same. And
By preventing the magnitude relationship between the values from being reversed, a dead point cannot be formed in the change in the load of the suspension, so that a smooth stroke change occurs and the ride comfort is good.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic side view showing a small snowmobile according to an embodiment of the present invention. FIG. 2 is a detailed configuration diagram showing a periphery of a pivot shaft of a rear swing arm according to the embodiment. FIG. 3 is a partially enlarged view for explaining the operation of the suspension of the small snowmobile according to the embodiment. FIG. 4 is an explanatory view of the operation of the suspension of the small snowmobile according to the embodiment. FIG. 5 is an explanatory diagram of a configuration of a small snowmobile in a prior application. [Description of Signs] 18 Transmission chain 19 Crawler driving sprocket 20 Crawler 25 Lower suspension 26 Upper suspension 30 Pivot shaft 32 Drive chain 35 Arm frame 36 Rear swing arm p2 Step

Claims (1)

(1) Claims 1. A crawler is wound around a crawler frame that extends below a vehicle body in a front-rear direction and has a free sprocket and a driving sprocket rotatably provided at front and rear ends. In a vehicle provided with a rear crawler, a lower part of which is curved downward by a lower rolling wheel rotatably provided on the crawler frame, the rear crawler has a pivot shaft at a front end of the vehicle body frame as a fulcrum. The rear end of the crawler frame is rotatably supported at the rear end of a swing arm, which is rotatably supported vertically and extends rearward and has a cushion between itself and the vehicle body frame, while the front end of the crawler frame is The rear crawler is supported by a suspension provided between the vehicle body frame and the rear crawler. The drive shaft and the transmission chain are arranged along the swing arm, and the pivot axis of the rear swing arm is located behind the step and near the crawler contact surface on a flat surface. A vehicle with a crawler, which is located substantially above, a crawler frame suspension is disposed forward of the pivot shaft, and an upper mounting end of the suspension is fixed to a body frame other than the rear swing arm. Suspension structure.