Four-wheeler rear wheel suspension system

Abstract

The invention discloses a rear wheel suspension system of a four-wheeler. The rear wheel suspension system comprises a four-wheeler frame, a rear wheel, a spring shock absorber and a Y-shaped swing arm, the rear wheel is coaxially connected to the rear wheel shaft, and the rear wheel shaft is coaxially sleeved with a shaft sleeve through a plurality of bearings. The Y-shaped swing arm is horizontally arranged in the front-back direction, the forked end of the Y-shaped swing arm faces forwards, and the non-forked end of the Y-shaped swing arm faces backwards. The upper end of the spring shock absorber is hinged to the four-wheeler frame through a hinge a, and the lower end is hinged to the non-forked end of the Y-shaped swing arm through a hinge b; the shaft sleeve is fixed with the non-forked end of the Y-shaped swing arm; a first hinge seat and a second hinge seat are mounted on the four-wheeler frame, and the first hinge seat and the second hinge seat are arranged in front of the shaft sleeve; the two tail ends of the forked end of the Y-shaped swing arm are hinged to the first hinge base and the second hinge base respectively. Impedance at the initial stage of upward jumping of the rear wheel can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of four-wheel vehicle suspension. Background Art

[0002] Spring shock absorbers are widely used in the suspension shock absorption structure of electric four-wheel karts, electric four-wheel sightseeing vehicles in scenic areas, off-road vehicles and ordinary cars. When the wheels roll to the raised part of the ground, the spring shock absorbers will adaptively contract upward to form an impedance for the upward movement of the rear wheels. However, in the initial stage of the upward jumping of the rear wheels, the impedance formed by the spring shock absorbers is relatively small due to the small deformation amount, which causes the people in the car to still feel a strong bumpy feeling even if there are only tiny potholes on the road. Summary of the invention

[0003] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a rear wheel suspension system for a four-wheeled vehicle, which can effectively improve the impedance at the initial stage of the rear wheel jumping upward.

[0004] Technical solution: To achieve the above-mentioned purpose, a rear wheel suspension system for a four-wheel vehicle of the present invention comprises a four-wheel vehicle frame, a rear wheel, a spring shock absorber and a Y-shaped swing arm; the rear wheel is coaxially connected to the rear wheel shaft, and a shaft sleeve is coaxially sleeved outside the rear wheel shaft through a plurality of bearings; the Y-shaped swing arm is horizontally arranged along the front-back direction, the bifurcated end of the Y-shaped swing arm faces forward, and the non-bifurcated end faces backward;

[0005] The upper end of the spring shock absorber is hinged to the four-wheel vehicle frame through hinge a, and the lower end is hinged to the non-forked end of the Y-shaped swing arm through hinge b; the shaft sleeve is fixed to the non-forked end of the Y-shaped swing arm; the first hinge seat and the second hinge seat are installed on the four-wheel vehicle frame, and the first hinge seat and the second hinge seat are located in front of the shaft sleeve; the two ends of the forked end of the Y-shaped swing arm are respectively hinged to the first hinge seat and the second hinge seat.

[0006] Furthermore, the non-forked end of the Y-shaped swing arm is provided with a circular arc concave section, the shaft sleeve fits the inner wall of the circular arc concave section, and a locking bolt through hole is provided on the circular arc concave section. The locking bolt passes through the locking bolt through hole and is locked on the locking hole on the shaft sleeve.

[0007] Furthermore, the upper ends of the first articulated seat and the second articulated seat are both fixed on the four-wheel vehicle frame.

[0008] Furthermore, the Y-shaped swing arm is composed of a main arm and an elastic bifurcated arm; the main arm extends in the front-to-back direction, and the elastic bifurcated arm forms an angle with the main arm; the rear end of the elastic bifurcated arm is fixedly connected to the middle part of the main arm through a fixed connecting piece;

[0009] The rear end of the main arm is hinged to the lower end of the spring shock absorber through hinge b, and the arc is concave at the rear section of the main arm;

[0010] The front end of the elastic bifurcated arm is hinged on the first hinge seat, and the front end of the main arm is hinged on the second hinge seat.

[0011] Furthermore, the elastic bifurcated arm is made of spring steel; and the main arm is made of structural steel.

[0012] Furthermore, the Y-shaped swing arm is composed of a rear swing arm a, a first front fork arm b and a second front fork arm c; the rear swing arm a extends in the front-to-back direction, and the first front fork arm b and the second front fork arm c are arranged at an angle; the front ends of the first front fork arm b and the second front fork arm c are respectively hingedly connected to the first hinge seat and the second hinge seat; the rear end of the rear swing arm a is hingedly connected to the lower end of the spring shock absorber through the b hinge; the rear end of the first front fork arm b, the rear end of the second front fork arm c and the front end of the rear swing arm a are hingedly connected on the same vertical hinge shaft.

[0013] Furthermore, a first bearing seat and a second bearing seat are fixedly arranged on the four-wheel vehicle frame and are distributed in the left and right directions. The four-wheel vehicle frame also includes a jitter offset compensation shaft extending in the left and right directions. The jitter offset compensation shaft is rotatably mounted on the first bearing seat and the second bearing seat through a bearing; a first section of external thread and a second external thread are arranged on the jitter offset compensation shaft. The first section of external thread and the second section of external thread have the same pitch and opposite spiral rotation directions; the first section of external thread and the second section of external thread are respectively threadedly provided with an a internal thread body and a b internal thread body;

[0014] The first and second hinged seats are rotatably mounted with a first vertical shaft and a second vertical shaft at their upper ends through bearings, and the first and second vertical shafts are respectively fixedly connected to the transverse internal threaded bodies a and b at their upper ends;

[0015] A ball top is provided at the upper end of the vertical hinge shaft; a rocker arm extending rearward and downward is vertically connected to the middle part of the runout offset compensation shaft; a torsion plate is coaxially provided at one end of the vertical hinge shaft, and a torsion spring is provided between the torsion plate and the second bearing seat. The torsion spring applies torque to the runout offset compensation shaft through the torsion plate, so that the rocker arm tends to swing downward around the runout offset compensation shaft, so that the lower side of the end of the rocker arm is always limited to contact with the ball top.

[0016] Furthermore, when the rocker arm drives the adaptive rotation of the runout offset compensation shaft by swinging upward, the internal thread body a and the internal thread body b move toward each other under the drive of the first section of the external thread and the second external thread with opposite spiral rotation directions, thereby reducing the angle between the first front fork arm b and the second front fork arm c.

[0017] Furthermore, it also includes a guide slide rod parallel to the runout offset compensation axis, and the two ends of the guide slide rod are respectively fixedly connected to the first bearing seat and the second bearing seat; the guide slide rod is movable and guided through the guide holes on the internal threaded body a and the internal threaded body b;

[0018] Furthermore, the first front fork arm b and the second front fork arm c are made of spring steel; and the rear swing arm a is made of structural steel.

[0019] Beneficial effects: In the first embodiment of the present invention, in addition to swinging upward around the first hinge seat under the linkage of the main arm, the elastic bifurcated arm can also adapt to a certain degree of bending and torsion elastic deformation in order to overcome motion interference. The bending and torsion elastic deformation is finally transmitted to the rear wheel to form the impedance of the rear wheel jumping upward in the initial stage, thereby enhancing the impedance of the rear wheel jumping upward in the initial stage, further suppressing the shaking and bumping feeling on slightly uneven road sections, and improving the comfort of passengers;

[0020] In the second embodiment, during the upward jumping of the rear wheel, the angle between the first front fork arm and the second front fork arm becomes smaller, thereby increasing the overall length of the Y-shaped swing arm, thereby causing the rear wheel to shift relatively backward, offsetting the forward shift of the rear wheel, and thus weakening the degree of front-to-rear shift during the upward jumping of the rear wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the overall three-dimensional schematic diagram of this scheme;

[0022] Figure 2 This is the overall front view of the scheme;

[0023] Figure 3 It is a schematic diagram of the frame structure;

[0024] Figure 4 It is a schematic diagram of the three-dimensional structure of the suspension of the first embodiment;

[0025] Figure 5 for Figure 4 Bottom view of

[0026] Figure 6 for Figure 4 A front view of

[0027] Figure 7 is a schematic diagram of the three-dimensional structure of the suspension of the second embodiment;

[0028] Figure 8 for Figure 7 Bottom view of

[0029] Fig. 9 for Figure 7 Front view of . DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] As attached Figures 1 to 9A rear wheel suspension system for a four-wheel vehicle is shown, and the specific examples in this case are electric four-wheel karts, sightseeing vehicles or off-road vehicles, etc., including a four-wheel vehicle frame 1, a rear wheel 2, a spring shock absorber 3 and a Y-shaped swing arm 4; the rear wheel 2 is coaxially connected to the rear wheel shaft 15, and a shaft sleeve 8 is coaxially sleeved on the outside of the rear wheel shaft 15 through a plurality of bearings; the Y-shaped swing arm 4 is horizontally arranged along the front-to-back direction, and the bifurcated end of the Y-shaped swing arm 4 faces forward and the non-bifurcated end faces backward; the upper end of the spring shock absorber 3 is hinged to the four-wheel vehicle frame 1 through a hinge 13, and the lower end is hinged to the non-bifurcated end of the Y-shaped swing arm 4 through a hinge 140; the shaft sleeve 8 is fixed to the non-bifurcated end of the Y-shaped swing arm 4; a first hinge seat 11 and a second hinge seat 12 are installed on the four-wheel vehicle frame 1, and the first hinge seat 11 and the second hinge seat 12 are in front of the shaft sleeve 8; the two ends of the bifurcated end of the Y-shaped swing arm 4 are respectively hinged to the first hinge seat 11 and the second hinge seat 12.

[0032] The non-forked end of the Y-shaped swing arm 4 is provided with a circular arc concave section 10, the shaft sleeve 8 fits the inner wall of the circular arc concave section 10, and a locking bolt through hole 47 is provided on the circular arc concave section 10. The locking bolt 9 passes through the locking bolt through hole 47 and is locked on the locking hole on the shaft sleeve 8.

[0033] Based on the above infrastructure, this solution provides the following two embodiments from two optimization perspectives:

[0034] The first embodiment, (such as Figure 4 , 5 , 6) as shown:

[0035] The upper ends of the first articulated seat 11 and the second articulated seat 12 are both fixed on the four-wheel vehicle frame 1 .

[0036] The Y-shaped swing arm 4 consists of a main arm 4a and an elastic forked arm 4b; the main arm 4a extends in the front-to-back direction, and the elastic forked arm 4b forms an angle with the main arm 4a, which is an acute angle of 10° to 20° in this case; the rear end of the elastic forked arm 4b is fixedly connected to the middle part of the main arm 4a through a fixed connecting piece 16; the rear end of the main arm 4a is hinged to the lower end of the spring shock absorber 3 through a b hinge 140, and the arc concave section 10 is at the rear section of the main arm 4a; the front end of the elastic forked arm 4b is hinged on the first hinge seat 11, and the front end of the main arm 4a is hinged on the second hinge seat 12; the elastic forked arm 4b is made of spring steel; the main arm 4a is made of structural steel, and its thickness is significantly greater than that of the elastic forked arm 4b, so in this embodiment, the main arm 4a is a relatively rigid structure relative to the elastic forked arm 4b.

[0037] Working principle of the first embodiment:

[0038] When the rear wheel 2 encounters an obstacle on the road and bounces upward, the spring shock absorber 3 adaptively contracts upward to form an impedance to the upward movement of the rear wheel 2. However, in the initial stage of the rear wheel 2 bouncing upward, the spring shock absorber 3 has a very small deformation amount, and the impedance formed is relatively small, which causes the occupants to feel a strong bump even if there are only tiny potholes on the road. In this solution, the upward bouncing of the rear wheel 2 will cause the main arm 4a to swing upward a certain distance around the second articulated seat 12, and then cause the "fixed connection member 16" to swing upward a certain distance around the axis of the second articulated seat 12. If the elastic forked arm 4b is also a rigid structure, in addition to swinging upward around the axis of the second articulated seat 12, the "fixed connection member 16" also needs to swing around the axis of the second articulated seat 12 at the same time. The axis of the seat 12 swings upward. Since the axes of the second articulated seat 12 and the second articulated seat 12 do not overlap, motion interference is formed. In this case, the elastic forked arm 4b is made of elastic spring steel. Therefore, during the process of the main arm 4a swinging upward around the second articulated seat 12 for a certain distance, the elastic forked arm 4b, in addition to swinging upward around the first articulated seat 11 under the linkage of the main arm 4a, will also adapt to a certain degree of bending and torsional elastic deformation in order to overcome the motion interference. The bending and torsional elastic deformation is finally transmitted to the rear wheel 2 to form an impedance for the initial stage of the rear wheel jumping upward, thereby enhancing the initial stage impedance of the rear wheel 2 jumping upward, further suppressing the shaking and bumping feeling on slightly bumpy roads, and improving passenger comfort.

[0039] The first embodiment has the following defects: when the rear wheel 2 bounces upward under the constraint of the main arm 4a, the originally horizontal main arm 4a will become tilted. Therefore, after the main arm 4a swings upward and becomes tilted, the rear wheel 2 will not only move upward but also move forward relative to the frame. During the bumpy process, the rear wheel 2 will move upward and forward relative to the frame at the same time, which will dynamically change the positioning parameters such as the camber angle and the toe angle, resulting in uneven tire contact surface and aggravated eccentric wear. In short, when the rear wheel 2 bounces upward under the constraint of the main arm 4a, if the rear wheel 2 has too large a front-to-rear relative displacement, it will bring many disadvantages.

[0040] Second embodiment (such as Figure 7 , 8 , 9) as shown:

[0041] The four-wheel vehicle frame 1 is fixedly provided with a first bearing seat 13 and a second bearing seat 14 distributed on the left and right sides, and also includes a beating offset compensation shaft 15 extending in the left and right directions, and the beating offset compensation shaft 15 is rotatably installed on the first bearing seat 13 and the second bearing seat 14 through a bearing; the beating offset compensation shaft 15 is provided with a first section of external thread 15a and a second external thread 15b, and the first section of external thread 15a and the second section of external thread 15b have the same pitch and opposite spiral rotation direction; the first section of external thread 15a and the second section of external thread 15b are respectively threadedly provided with an a internal thread body 41 and a b internal thread body 42;

[0042] It also includes a guide slide rod 42 parallel to the runout offset compensation shaft 15, and the two ends of the guide slide rod 42 are respectively fixedly connected to the first bearing seat 13 and the second bearing seat 14; the guide slide rod 42 is movable and guided through the guide holes 81 on the a internal thread body 41 and the b internal thread body 42;

[0043] The first and second hinged seats 11 and 12 are rotatably mounted with a first vertical shaft 81 and a second vertical shaft 82 at their upper ends through bearings. The upper ends of the first and second vertical shafts 81 and 82 are respectively fixedly connected to the transverse a internal threaded body 41 and b internal threaded body 42.

[0044] The Y-shaped swing arm 4 is composed of a rear swing arm 4aa, a first front fork arm 4bb and a second front fork arm 4cc; the rear swing arm 4aa extends in the front-to-back direction, and the first front fork arm 4bb and the second front fork arm 4cc are arranged at an angle, which is an acute angle of 10° to 20° in this case; the front ends of the first front fork arm 4bb and the second front fork arm 4cc are respectively hingedly connected to the first hinge seat 11 and the second hinge seat 12; the rear end of the rear swing arm 4aa is hingedly connected to the lower end of the spring shock absorber 3 through the b hinge 140; the rear end of the first front fork arm 4bb, the rear end of the second front fork arm 4cc and the front end of the rear swing arm 4aa are hingedly connected to the same vertical hinge shaft 5;

[0045] A ball top 6 is provided at the upper end of the vertical hinge shaft 5; a swing rod 7 extending backward and downward is vertically connected to the middle of the runout offset compensation shaft 15; a torsion plate 44 is coaxially provided at one end of the vertical hinge shaft 5, and a torsion spring 43 is provided between the torsion plate 44 and the second bearing seat 14. The torsion spring 43 applies torque to the runout offset compensation shaft 15 through the torsion plate 44, so that the swing rod 7 has a tendency to swing downward around the runout offset compensation shaft 15, so that the lower side of the end of the swing rod 7 is always limited to contact the ball top 6;

[0046] When the rocker arm 7 drives the adaptive rotation of the runout offset compensation shaft 15 by swinging upward, the internal thread body a 41 and the internal thread body b 42 move toward each other driven by the first section of the external thread 15a and the second section of the external thread 15b having opposite spiral rotation directions, thereby reducing the angle between the first front fork arm 4bb and the second front fork arm 4cc.

[0047] The first front fork arm 4bb, the second front fork arm 4cc and the rear swing arm 4aa are all made of structural steel.

[0048] The working principle of the second embodiment:

[0049] When the rear wheel 2 encounters a road obstacle and bounces upward, the spring shock absorber 3 adaptively contracts upward to form an impedance for the upward movement of the rear wheel 2, and the Y-shaped swing arm 4 swings upward following the rear wheel 2. Since the Y-shaped swing arm 4 is horizontal in the initial state, if the positions of the first articulated seat 11 and the second articulated seat 12 are fixed (the positions of the first articulated seat 11 and the second articulated seat 12 in the first embodiment are fixed), the rear wheel 2 will inevitably deviate forward a certain distance relative to the four-wheel vehicle frame 1 during the upward jumping process; in this solution, during the upward jumping process of the rear wheel 2, the rear swing arm 4aa jumps upward following the rear wheel 2, and the first front fork arm 4bb and the second front fork arm 4cc swing upward around the first articulated seat 11 and the second articulated seat 12 respectively under the linkage of the rear swing arm 4aa, and the first vertical axis 81 and the second vertical axis 82 rotate adaptively, and at the same time the vertical articulated shaft 5 jumps upward following the rear swing arm 4aa. After a certain distance, the vertical articulated shaft 5 will push the swing rod 7 upward to swing upward in the process of jumping up a certain distance with the rear swing arm 4aa, and the swing rod 7 will drive the jumping offset compensation shaft 15 to rotate accordingly through the upward swing, and the a internal thread body 41 and the b internal thread body 42 will move closer to each other under the drive of the first section of external thread 15a and the second external thread 15b with opposite spiral rotation directions, so that the angle between the first front fork arm 4bb and the second front fork arm 4cc becomes smaller; the angle between the first front fork arm 4bb and the second front fork arm 4cc becomes smaller, so that the overall total length of the Y-shaped swing arm 4 increases (the degree of increase is positively correlated with the pitch of the first section of external thread 15a and the second section of external thread 15b, and the pitch size is adaptively selected according to actual conditions), thereby causing the rear wheel 2 to relatively deviate backward, forming a counteract with the forward deviation of the rear wheel 2, thereby weakening the degree of front and rear deviation of the rear wheel 2 during the upward jumping process;

[0050] At the same time, in the above process, the resistance formed by the transmission process of the a internal threaded body 41 and the b internal threaded body 42 respectively with the a internal threaded body 41 and the b internal threaded body 42 just constitutes the impedance of the rear wheel jumping upward in the initial stage, thereby enhancing the initial stage impedance of the rear wheel 2 jumping upward, further suppressing the shaking and bumping feeling on slightly bumpy roads, and improving passenger comfort.

[0051] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A rear wheel suspension system for a four-wheel vehicle, characterized in that: The invention comprises a four-wheel vehicle frame (1), a rear wheel (2), a spring shock absorber (3) and a Y-shaped swing arm (4); the rear wheel (2) is coaxially connected to a rear wheel shaft (15), and a shaft sleeve (8) is coaxially sleeved on the outside of the rear wheel shaft (15) through a plurality of bearings; the Y-shaped swing arm (4) is horizontally arranged in the front-back direction, with the bifurcated end of the Y-shaped swing arm (4) facing forward and the non-bifurcated end facing backward; The upper end of the spring shock absorber (3) is hinged to the four-wheel vehicle frame (1) through an a hinge (13), and the lower end is hinged to the non-forked end of the Y-shaped swing arm (4) through a b hinge (140); the shaft sleeve (8) is fixed to the non-forked end of the Y-shaped swing arm (4); a first hinge seat (11) and a second hinge seat (12) are installed on the four-wheel vehicle frame (1), and the first hinge seat (11) and the second hinge seat (12) are located in front of the shaft sleeve (8); the two ends of the forked end of the Y-shaped swing arm (4) are respectively hinged to the first hinge seat (11) and the second hinge seat (12).

2. A four-wheel vehicle rear wheel suspension system according to claim 1, characterized in that: The non-branched end of the Y-shaped swing arm (4) is provided with a circular arc concave section (10), the shaft sleeve (8) fits the inner wall of the circular arc concave section (10), and a locking bolt through hole (47) is provided on the circular arc concave section (10). The locking bolt (9) passes through the locking bolt through hole (47) and is locked on the locking hole on the shaft sleeve (8).

3. A four-wheel vehicle rear wheel suspension system according to claim 1, characterized in that: The upper ends of the first hinged seat (11) and the second hinged seat (12) are both fixed on the four-wheel vehicle frame (1).

4. A four-wheel vehicle rear wheel suspension system according to claim 3, characterized in that: The Y-shaped swing arm (4) is composed of a main arm (4a) and an elastic bifurcated arm (4b); the main arm (4a) extends in the front-rear direction, and the elastic bifurcated arm (4b) forms an angle with the main arm (4a); the rear end of the elastic bifurcated arm (4b) is fixedly connected to the middle part of the main arm (4a) through a fixed connecting piece (16); The rear end of the main arm (4a) is hinged to the lower end of the spring shock absorber (3) through a hinge (140), and a circular arc concave section (10) is provided at the rear section of the main arm (4a); The front end of the elastic bifurcated arm (4b) is hinged on the first hinge seat (11), and the front end of the main arm (4a) is hinged on the second hinge seat (12).

5. A four-wheel vehicle rear wheel suspension system according to claim 4, characterized in that: The elastic bifurcated arm (4b) is made of spring steel; and the main arm (4a) is made of structural steel.

6. A four-wheel vehicle rear wheel suspension system according to claim 1, characterized in that: The Y-shaped swing arm (4) is composed of a rear swing arm (4aa), a first front fork arm (4bb) and a second front fork arm (4cc); the rear swing arm (4aa) extends in the front-to-back direction, and the first front fork arm (4bb) and the second front fork arm (4cc) are arranged at an angle; the front ends of the first front fork arm (4bb) and the second front fork arm (4cc) are respectively hingedly connected to the first hinge seat (11) and the second hinge seat (12); the rear end of the rear swing arm (4aa) is hingedly connected to the lower end of the spring shock absorber (3) through the b hinge (140); the rear end of the first front fork arm (4bb), the rear end of the second front fork arm (4cc) and the front end of the rear swing arm (4aa) are hingedly connected to the same vertical hinge shaft (5).

7. A four-wheel vehicle rear wheel suspension system according to claim 6, characterized in that: A first bearing seat (13) and a second bearing seat (14) are fixedly arranged on the four-wheel vehicle frame (1), and the frame also includes a jitter offset compensation shaft (15) extending in the left-right direction, wherein the jitter offset compensation shaft (15) is rotatably mounted on the first bearing seat (13) and the second bearing seat (14) via a bearing; a first section of external thread (15a) and a second external thread (15b) are arranged on the jitter offset compensation shaft (15), wherein the first section of external thread (15a) and the second section of external thread (15b) have the same pitch and opposite spiral directions; and the first section of external thread (15a) and the second section of external thread (15b) are respectively provided with an a internal thread body (41) and a b internal thread body (42) in a threaded manner; A first vertical shaft (81) and a second vertical shaft (82) are rotatably mounted on the upper ends of the first hinge seat (11) and the second hinge seat (12) via bearings, and the upper ends of the first vertical shaft (81) and the second vertical shaft (82) are respectively fixedly connected to a transverse internal threaded body a (41) and a transverse internal threaded body b (42); A ball top (6) is arranged at the upper end of the vertical hinge shaft (5); a swing rod (7) extending rearward and downward is vertically connected to the middle part of the vibration offset compensation shaft (15); a torsion plate (44) is coaxially arranged on one end of the vertical hinge shaft (5); a torsion spring (43) is arranged between the torsion plate (44) and the second bearing seat (14); the torsion spring (43) applies torque to the vibration offset compensation shaft (15) through the torsion plate (44), so that the swing rod (7) tends to swing downward around the vibration offset compensation shaft (15), so that the lower side of the end of the swing rod (7) is always limited to contact the ball top (6).

8. A four-wheel vehicle rear wheel suspension system according to claim 7, characterized in that: When the rocker arm (7) swings upward to drive the adaptive rotation of the vibration offset compensation shaft (15), the a internal thread body (41) and the b internal thread body (42) move toward each other under the drive of the first section of external thread (15a) and the second section of external thread (15b) having opposite spiral rotation directions, thereby reducing the angle between the first front fork arm (4bb) and the second front fork arm (4cc).

9. A four-wheel vehicle rear wheel suspension system according to claim 8, characterized in that: It also includes a guide slide bar (42) parallel to the runout offset compensation shaft (15), and the two ends of the guide slide bar (42) are respectively fixedly connected to the first bearing seat (13) and the second bearing seat (14); the guide slide bar (42) is movably guided to pass through the guide holes (81) on the a internal thread body (41) and the b internal thread body (42).

10. A four-wheel vehicle rear wheel suspension system according to claim 6, characterized in that: The first front fork arm (4bb) and the second front fork arm (4cc) are made of spring steel; the rear swing arm (4aa) is made of structural steel.

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