JPH08142622A - Suspension for vehicle - Google Patents

Abstract

PURPOSE: To reduce the slidable friction of a shock absorber by canceling the transverse force to be generated when the vertical load is applied to a coil spring by the transverse force to be applied to the shock absorber based on the particulars when a suspension is activated. CONSTITUTION: The lateral force on a rod guide is obtained as the resultant of the components Fa L in the lateral direction to be generated by the vertical load Fv , and the lateral force by the body bending of a coil spring 12 and the synthesized lateral force to be generated based on the bending moments to be respectively generated at the upper and lower end parts of the shock absorber 11. The coil spring 12 and a lower seat 18 are turned around the outer circumference of a cylinder 13, and the direction of the component Fa L in the lateral direction is set at the position where the component Ea L in the lateral direction is canceled by the synthesized lateral force to reduce or eliminate the lateral force on the rod guide. Thus, the slidable friction to be generated on the shock absorber can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension system,
In particular, the present invention relates to a vehicle suspension device in which a shock absorber and a coil spring are coaxially arranged.

[0002]

2. Description of the Related Art In general, a strut suspension is known as an example of a vehicle suspension system in which a shock absorber and a coil spring are coaxially arranged. This strut suspension is characterized by having a link function by using a shock absorber as a strut.

The upper end of the shock absorber is swingably connected to the vehicle body via an upper support made of rubber, and the lower end is attached to a steering knuckle on which a tire is mounted. The steering knuckle is attached to a lower arm that is vertically swingable. The strut suspension having the above structure has various advantages over other suspension structures in that the structure is simple and small, the alignment error is small, and the cost performance is excellent.

However, in the strut suspension, since the shock absorber is used as the strut as described above, generally, bending stress is easily applied to the shock absorber. Due to this bending stress, sliding friction occurs between the piston rod and the seal part arranged on the cylinder when the shock absorber expands and contracts, which causes deterioration of the seal part and deterioration of ride comfort. Resulting in.

As a suspension system for a vehicle equipped with a means for preventing the sliding friction, for example, Japanese Unexamined Patent Publication No. 10341/1991.
A suspension system for a vehicular vehicle, which is disclosed in Japanese Patent Publication No. 9, has been proposed. The vehicle suspension device disclosed in the publication has a structure in which the coil spring is offset with respect to the strut axis in order to reduce the bending stress acting on the shock absorber by the coil spring.

[0006]

However, in the shock absorber, when the vehicle suspension device is operating (bound / rebound), the bending stress which is a problem in the vehicle suspension device disclosed in the above-mentioned publication is reduced. In addition, various forces such as lateral force due to the occurrence of bending of the coil spring and bending moment generated at the upper and lower ends of the shock absorber are applied.

However, the suspension system for a vehicle disclosed in the above publication has a structure in which only the bending stress acting on the shock absorber is simply reduced by the coil spring, and the lateral force by the coil spring itself, the shock absorber mounting portion, etc. The lateral force generated at is not taken into consideration. Therefore, in the vehicle suspension device disclosed in the above publication, the sliding friction generated between the piston rod and the seal portion of the cylinder cannot be sufficiently reduced, and therefore the seal portion of the shock absorber is still deteriorated. There was a problem that the riding comfort deteriorates as it occurs.

The present invention has been made in view of the above points, and a lateral force generated when a vertical load is applied to the coil spring and a lateral force acting on the shock absorber based on the specifications when the suspension device is operated. An object of the present invention is to provide a suspension system for a vehicle, which can reduce sliding wear of a shock absorber and can improve ride comfort by constructing so as to cancel out the force.

[0009]

In order to solve the above problems, the present invention provides a suspension system for a vehicle in which a shock absorber and a coil spring are coaxially arranged, on the basis of specifications acting on the shock absorber. , Lateral force acting on the shock absorber when vibration is input from the road surface,
The arrangement direction of the coil springs is set so that the lateral force generated by the vertical load acting on the coil springs at the time of the vibration input cancels each other.

[0010]

As described above, in the vehicle suspension system in which the shock absorber and the coil spring are coaxially arranged, various forces act on the shock absorber when vibration is input from the road surface. Specifically, (1) Lateral force due to the body bending of the coil spring, (2) Bending moment generated at the upper end of the shock absorber, (3) Bending moment generated at the lower end of the shock absorber, (4) Various forces and moments such as lateral force generated by the vertical load acting on the coil spring act.

Here, the upper end portion of the shock absorber provided in the strut-type vehicle suspension device is fixed to the vehicle and is not rotatable (swing is possible). Therefore, among the above forces and moments, (1)
Calculate the lateral force (perpendicular to the expansion / contraction direction) acting on the shock absorber from the moment of (3).
When the resultant force of the forces acting in each lateral direction (hereinafter referred to as the synthetic lateral force) is obtained, the synthetic lateral force always becomes a force acting in a fixed direction.

On the other hand, according to the experiments by the present inventor, the lateral force generated by the vertical load acting on the coil spring in (4) described above can change the acting direction by rotating the coil spring. Was found. Therefore, by arranging the coil spring so that the acting direction of the combined lateral force and the lateral force generated by the vertical load acting on the coil spring face each other, the combined lateral force and the lateral force generated by the vertical load are canceled. Can
Therefore, the external force acting on the shock absorber at the time of vibration input from the road surface can be reduced, sliding wear can be reduced, and riding comfort can be improved.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows a vehicle suspension device 1 to which the present invention can be applied. In the example shown in the figure, a 4-link type vehicle suspension device 1 is shown. In the figure, reference numeral 2 is an axle housing, and a differential gear 3 is arranged in the center thereof. In addition, a pair of axles (not shown in the figure) are arranged inside the axle housing 2,
One end of each axle is meshed with the differential gear 3 and the other end is provided with an axle hub 4 (only one of which is shown) having wheels.

The upper control rod 5 is provided in the vicinity of the position of each axle hub 4 of the axle housing 2.
And one end of the lower control rod 6 is a bush 7,
8 are swingably connected to each other (only one is shown). The other ends of the upper control rod 5 and the lower control rod 6 are swingably connected to a vehicle body (not shown) via bushes 9 and 10. The axle housing 2 is positioned by the total of four control rods 5 and 6.

Further, a shock absorber 11 is arranged near the position of each axle hub 4 of the axle housing 2, and a coil spring 12 is arranged at a predetermined position above the shock absorber 11. The shock absorber 11 and the coil spring 12 are arranged coaxially. This shock absorber 11
The coil spring 12 damps vibrations transmitted from the road surface and prevents them from being transmitted to the vehicle body.

The structures of the shock absorber 11 and the coil spring 12 will be described in detail with reference to FIGS. 7 and 10 in addition to FIG. 7 is a schematic configuration diagram of the shock absorber 11 and the coil spring 12, and FIG. 10 is a schematic sectional view of the shock absorber 11. The shock absorber 11 is, for example, a hydraulic shock absorber, and is shown in FIG.
0, cylinder 13, piston rod 1
4, piston 22, rod guide 23, seal 24
And the like. A piston 22 is arranged at the end of the piston rod 14, and the piston 2
2 is configured to slide the cylinder 13 in a liquid-tight manner in accordance with the operation of the piston rod 14. Also, the piston 2
2 is provided with a damping force generating mechanism including a communication hole and a valve seat (not shown). Further, the cylinder 13 is filled with oil liquid.

When the piston rod 14 moves in response to the applied vibration, the piston 22 slides in the cylinder 13 accordingly. At this time, the oil liquid filled in the cylinder 13 passes through the inside of the piston 22 via the damping force generating mechanism, and the damping force is generated by the force that suppresses the movement of the piston 22 generated at this time. The rod guide portion 23 has a function of guiding the movement of the piston rod 14, and the seal portion 24 also has a function of preventing the oil liquid filled in the cylinder 13 from leaking to the outside.

On the other hand, a lower bush 15 is arranged at the lower end of the shock absorber 11 having the above-mentioned structure, and a bracket 16 fixed to the axle housing 2 is provided.
It is configured so as to be supported by a support shaft 17 arranged at.
Therefore, the lower end of the shock absorber 11 is swingably attached to the axle housing 2.

Further, a flange-shaped lower seat 18 is provided on a side portion of the cylinder 13 constituting the shock absorber 11, and an upper support 19 is provided on an upper end portion of the piston rod 14. Further, the coil spring 12 is configured to be interposed between the lower seat 18 and the upper support 19 while accumulating elastic force.
A step portion 20 is formed at a predetermined position of the lower seat 18, and the lower end portion 12 a of the coil spring 12 is formed by the step portion 2.
It is locked at 0. Further, the upper end portion 12b of the coil spring 12 is configured to be locked to the upper support 19.

The upper support 19 is fixed to the vehicle body through a plurality of bolts (not shown).
The upper support 19 is provided with an elastic body 21, and the elastic body 21 can also absorb vibrations and impacts from wheels on the upper support 19. In the above configuration, the mounting direction of the upper support 19 with respect to the vehicle body and the mounting direction of the lower bush 15 with respect to the axle housing 2 are predetermined for each vehicle and cannot be changed. On the other hand, since the lower seat 18 is fixed to the outer peripheral portion of the cylinder 13 by, for example, welding, its mounting direction can be easily changed.

Next, the experiments conducted by the present inventor will be described mainly with reference to FIGS. 1 to 11. As described above, the mounting direction of the upper support 19 with respect to the vehicle body,
The mounting direction of the lower bush 15 to the axle housing 2 is predetermined for each vehicle and cannot be changed. Therefore, the inventor has found that the lower seat 1 on which the lower end 12a of the coil spring 12 is locked.
The experiment which changed the attachment position of 8 was implemented.

Specifically, the coil spring 12 and the lower seat 18 are rotated around the outer periphery of the cylinder 13, and the lateral force acting on the rod guide portion 23 (see FIG. 10) arranged on the shock absorber 11 at each mounting position. (hereinafter, the rod that guides the lateral force F _R) size was measured. This rod guide lateral force F _R is the piston rod 14
And the rod guide portion 23 have a great influence on the sliding wear and the riding comfort of the vehicle, and the rod guide lateral force F
_The larger the _R is, the more the sliding wear becomes more severe, and the riding comfort becomes rugged and poor.

FIG. 2 shows the experimental result of the above experiment conducted by the present inventor. The experimental results shown in the figure show the rod guide lateral force F _R when the coil spring 12 and the lower seat 18 are rotated around the outer circumference of the cylinder 13 in the right rear wheel (RR) of the vehicle in the standard vehicle height state. . In the figure, F _R1 is a rod guide lateral force when the coil spring 12 and the lower seat 18 are mounted at arbitrary positions on the cylinder 13, and F _R4 is shown from the above arbitrary positions on the cylinder 13 side. Shows the lateral force of the rod guide when it is rotated by 180 ° around the outer circumference. Also,
In the figure, F _r indicates the front of the vehicle, R _r indicates the rear of the vehicle, RH indicates the right direction of the vehicle, and LH indicates the left direction of the vehicle.

As shown in the figure, by rotating the coil spring 12 and the lower seat 18 around the outer circumference of the cylinder 13, it can be seen that the lateral force of the rod guide changes its direction. Moreover, the size also has a slightly different value. The reason why the direction of the rod guide lateral force is changed by rotating the coil spring 12 and the lower seat 18 around the outer circumference of the cylinder 13 as described above is considered to be as follows.

Attention is now paid to the vertical load applied to the coil spring 12. As shown in FIG. 11, when the vertical load Fv is applied to the coil spring 12,
An elastic force indicated by an arrow F in the drawing is generated in the coil spring 12. In addition, as described above, the step portion 2 is provided on the lower seat 18.
0 is formed, and the lower end portion 1 of the coil spring 12 is formed.
Since 2a is engaged with the stepped portion 20, the force F _a acting as a reaction of the elastic force F generated by the coil spring 12 in Roashito 18. Then, the lateral component force F _{aL of} this force F _a acts on the cylinder 13, and the lateral component force F _{aL of} this F _a acts as part of the rod guide lateral force F _R.

The position where the lateral component force F _{aL which is} the rod guide lateral force F _R acts is the position where the lower end portion 12 a of the coil spring 12 engages with the step portion 20 of the lower seat 18. Therefore, by rotating the coil spring 12 and the lower seat 18 around the outer circumference of the cylinder 13 as described above, the lower end portion 1 of the coil spring 12 is naturally rotated.
The position at which 2a engages with the step portion 20 of the lower seat 18 is also rotationally displaced, and the direction in which the lateral component force F _aL acts also changes.

For the above reason, the coil spring 12 and
And lower seat 18 around the outer circumference of cylinder 13
If the rod guide lateral force F_RSeems to change
It Based on the above matters, the present inventor has found that the coil spring 1
2 and lower seat 18 around the outer circumference of the cylinder 13
Lateral force F at each rotation angle _RTo
The required experiment was conducted. Figure 3 shows the experimental results.
Fig. 1 (A) shows the lateral force F of the rod guide._RAsking for
Shows the location. Fig. 1 (A) shows the right rear wheel shock absorber.
FIG. 2 is a plan view of the bussaw 11 (for convenience of explanation, the same is shown)
The lower bush 15 is also shown in the figure).

In the experiment shown in FIG. 3, phase 1 is shown in FIG.
~ Rotate the coil spring 12 and the lower seat 18 around the outer periphery of the cylinder 13 so that the lower end portion 12a of the coil spring 12 is positioned at each position shown by phase 5.
The lateral force F _R at each position was determined. The phase 1 is the axial direction of the lower bush 15 and the right side position of the lower bush 15, the phase 2 is the position rotated 45 ° counterclockwise from the phase 1, and the phase 3 is the axial direction of the lower bush 15. Is perpendicular to the lower bush 15 and is in the front position of the lower bush 15, phase 4 is in the axial direction of the lower bush 15 and is on the left side of the lower bush 15, and phase 5 is in the direction perpendicular to the axial direction of the lower bush 15. And it is a rear position of the lower bush 15.

Further, in FIG. 3, F _R1 is the rod guide lateral force in phase 1, F _R2 is the rod guide lateral force in phase 2, F _R3 is the rod guide lateral force in phase 3, and F _R4 is It is the rod guide lateral force in phase 4, and F _R5 is the rod guide lateral force in phase 5.
From the experimental results shown in FIG. 3, by rotating the coil spring 12 and the lower seat 18 around the outer periphery of the cylinder 13, the lateral directions of the rod guides F _{R1 to} F _R5 change their directions, and their magnitudes are different. I see.

By the way, when the shock absorber 11 and the coil spring 12 are actually mounted on a vehicle, the force acting on the shock absorber 11 due to vibrations from the wheels is not limited to the vertical load F _V described above. That is, as shown in FIG. 10, the lateral force F _S due to the body bending of the coil spring 12, the bending moment M1 generated at the upper end of the shock absorber 11, and the bending moment generated at the lower end of the shock absorber 11. M2
Etc. also act on the shock absorber 11.

Here, the body bending of the coil spring 12 means that vibration is applied from a state where the coil spring 12 shown in FIG. 8 is expanded, and the shock absorber 11 contracts as shown in FIG. Spring 1
When 2 is extended, it means that the coil spring 12 is deformed from the cylindrical shape. In this way, when the coil spring 12 is bent, the coil spring 12
Lateral force F _S is generated on the lower seat 18 due to the deformation.

Further, as described above, the upper support 19 arranged at the upper end of the shock absorber 11 is connected to the vehicle body through the elastic body 21. Therefore, when the shock absorber 11 swings due to the application of vibration, the elastic body 21 is elastically deformed by this swinging force, and accordingly, a bending moment M1 is generated at the upper end portion of the shock absorber 11.

Further, the lower bush 15 supported by the support shaft 17 is arranged at the lower end of the shock absorber 11, and when the shock absorber 11 swings due to the vibration application as described above, the support shaft 17 is provided. And twisting occur between the lower bush 15 and the lower bush 15, and due to this, the bending moment M also occurs at the lower end of the shock absorber 11.
2 occurs.

Therefore, the present inventor has proposed the above-mentioned lateral force F._S, And
And the bending moments M1 and M2
The lateral force applied to the sober 11 is obtained and the applied force
The result of obtaining the direction is shown in FIG. F in the figure_bIndicates
Lateral force F due to the above specifications _SAnd each bending moment M
A force that combines the forces generated by 1 and M2 (hereinafter, this force
Is called synthetic lateral force).

As described above, the upper support 1
The mounting direction of the vehicle body 9 on the vehicle body and the mounting direction of the lower bush 15 on the axle housing 2 are predetermined for each vehicle and cannot be changed. For this reason, the body curve generated in the coil spring 12 is always deformed in a constant direction, and the bending moment M1 generated in the upper support 19 and the bending moment M2 generated in the lower bush 15 are also always generated in a constant direction. Becomes Therefore, the lateral force F _S and the combined lateral force F _b generated by the bending moments M1 and M2 are also forces that always act in a fixed direction (however, the magnitude depends on the magnitude of vibration applied from the wheels, etc.). different).

Summarizing the above experimental results, the rod guide lateral force F _R which greatly affects the sliding wear generated between the piston rod 14 and the rod guide portion 23 and the riding comfort of the vehicle is the vertical load F _V The lateral component force F _aL generated by the above, the lateral force F _S due to the body bending of the coil spring 12, and the combined lateral force F _b generated based on the bending moments M1, M2, etc. generated at the upper and lower ends of the shock absorber 11, respectively. Required as a result.

The lateral component force F _aL generated by the vertical load F _V is the coil spring 12 and the lower seat 1.
It can be rotated by rotating 8 around the outer circumference of the cylinder 13. Therefore, by rotating the coil spring 12 and the lower seat 18 around the outer circumference of the cylinder 13, the direction in which the lateral component force F _aL acts on the position where the lateral component force F _aL and the synthetic lateral force F _b cancel each other out. By setting, the rod guide lateral force F _R can be reduced or eliminated.

FIG. 5 shows the lateral component force F _aL and the combined lateral force F _b.
It is the figure which represented both and. Here, attention is paid to the lateral component forces F _{aL2 and} F _aL3 of the phase 2 and the phase 3 shown in FIG.
Now, _assuming that the values obtained by _dividing the combined lateral force F _b in the directions in which the lateral component forces F _aL2, F _aL3 act are F _{b1 and} F _b2 , the lateral component force F _{aL2 of} phase 2 and the component force F _b1 are The forces F _{aL2 and} F _b1 are opposed to each other, and the forces F _{aL2 and} F _b1 cancel each other out. _{Therefore, the} rod guide lateral force F _R obtained as the resultant force of the forces F _{aL2 and} F _b1 has a small value. Similarly, the lateral component force F _{aL3 of} phase 3 and the component force F _b2 are forces opposing each other, and these forces F _aL3, F _b2 cancel each other out, so that each force F _aL3,
The rod guide lateral force F _R obtained as the resultant force of F _b2 has a small value.

FIG. 1B shows the right rear wheel (R) when the vehicle suspension system according to the present invention is actually mounted on a vehicle.
R) and the left rear wheel (RL) rod guide lateral force F _R are shown. This figure shows the lower end portion 1 of the coil spring 12 at each position of the phases 1 to 5 shown in FIG.
The coil spring 12 and the lower seat 18 are rotated around the outer circumference of the cylinder 13 so that 2a is positioned, and the direction and magnitude of the rod guide lateral force F _R at each position are shown.

In FIG. 1B, F _RR1 is the rod guide lateral force of the right rear wheel in phase 1, F _RR2 is the rod guide lateral force of the right rear wheel in phase 2, and F _RR2
RR3 is the rod guide lateral force of the right rear wheel in phase 3, F _RR4 is the rod guide lateral force of the right rear wheel in phase 4, and F _RR5 is the rod guide lateral force of the right rear wheel in phase 5. Further, F _RL1 is rod guide lateral force of the left rear wheel in the phase 1, F _RL2 is rod guide lateral force of the left rear wheel in the phase 2, F _RL3 rod guide lateral force of the left rear wheel in the phase 3 And F _RL4 is the rod guide lateral force of the left rear wheel in phase 4, and F _RL4 is
_RL5 is the rod guide lateral force of the left rear wheel in phase 5.

The experimental results of the right rear wheel (RR) shown in the same figure correspond to the experimental results described with reference to FIGS. 3 to 5 described above. Therefore, in the rod guide lateral forces F _RR2, F _RR3 in phase 2 and phase 3, the lateral component force F _aL2 and the component force F _b1 cancel each other out, and the lateral component force F _aL2.
And the component force F _b2 cancel each other out, resulting in a small value. On the other hand, in the phase 5 in which the combined lateral force F _b and the lateral component force F _aL are in the same direction, the combined lateral force F _{b is}
And the lateral component force F _aL are superimposed, the rod guide lateral force F _RR5 has a large value.

Therefore, according to the experimental result shown in FIG. 1, the coil spring 12 and the lower seat 18 are attached to the cylinder 13.
The lateral component force F _aL
It was demonstrated that the rod guide lateral force F _R can be reduced by setting the direction in which the lateral component force F _aL acts at a position where the combined lateral force F _b and the combined lateral force F _b cancel each other. In the present embodiment, since carrying out the only experiments on five points of the phase 1-5, the embodiment with the lateral component force F _aL and resultant lateral force F _b is completely opposed but was not obtained, the coil it is possible to state that the lateral component force F _aL and resultant lateral force F _b is opposed to the straight line in opposite directions by a spring 12 and Roashito 18 sets the rotation angle of the cylinder 13 appropriately, the With this structure, the value of the rod guide lateral force F _R can be reduced most efficiently. By reducing the value of the lateral force F _R of the rod guide in this way, it is possible to reduce the sliding wear caused by the sliding contact between the piston rod 14 and the rod guide portion 23, and the rugged feeling during riding. It is also possible to improve the riding comfort.

Although the present invention is applied to the four-link type vehicle suspension system 1 in the above embodiment, the present invention is arranged so that the shock absorber 11 and the coil spring 12 are coaxial with each other. Of course, it can be widely applied to a vehicle suspension device having the above configuration.

[0044]

As described above, according to the present invention, it is possible to cancel the combined lateral force and the lateral force generated by the vertical load,
Therefore, the external force acting on the shock absorber at the time of vibration input from the road surface can be reduced, the sliding wear generated on the shock absorber can be reduced, and the riding comfort can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an experimental result for obtaining a rod guide lateral force F _R when a vehicle suspension system according to an embodiment of the present invention is mounted on a vehicle.

FIG. 2 is a diagram showing an experimental result in which a rod guide lateral force F _R is obtained when a mounting position of a lower seat to which a lower end portion of a coil spring is locked is changed.

FIG. 3 is a diagram showing an experimental result of an experiment in which a coil spring and a lower seat are rotated around an outer circumference of a cylinder at various rotation angles, and a lateral component force F _aL at each rotation angle is obtained.

FIG. 4 is a diagram showing an experimental result for obtaining a combined lateral force F _b .

FIG. 5 is a diagram showing both a lateral component force F _aL and a combined lateral force F _b .

FIG. 6 is a perspective view showing a vehicle suspension device to which the present invention can be applied.

FIG. 7 is a schematic configuration diagram of a shock absorber and a coil spring.

FIG. 8 is a schematic configuration diagram showing a shock absorber and a coil spring in a state where the coil spring is contracted.

FIG. 9 is a view showing a state in which a coil spring is bent.

FIG. 10 is a schematic sectional view of a shock absorber.

FIG. 11 is a diagram for explaining a force acting on a coil spring to which a vertical load is applied.

[Explanation of symbols]

 1 Vehicle Suspension Device 2 Axle Housing 5 Upper Control Rod 6 Lower Control Rod 11 Shock Absorber 12 Coil Spring 12a Lower End 13 Cylinder 14 Piston Rod 18 Lower Support 19 Upper Port 20 Step 21 Elastic Body 22 Piston 23 Rod Guide 24 Seal Part

Claims (1)

[Claims] 1. A suspension system for a vehicle in which a shock absorber and a coil spring are coaxially arranged, and a lateral force acting on the shock absorber at the time of vibration input from a road surface based on specifications acting on the shock absorber. And a lateral force generated by a vertical load acting on the coil spring when the vibration is input, and the arrangement directions of the coil springs are set so as to cancel each other.