JP3489268B2 - Active suspension - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension which reduces friction generated in a fluid pressure cylinder.

[0002]

2. Description of the Related Art As a technique for reducing friction generated in a sliding portion of a fluid pressure cylinder in a vehicle suspension, for example, a strut type suspension shown in FIGS. 15 and 16 and Japanese Utility Model Laid-Open No. 56-150603 are disclosed. The techniques described are known.

In the strut type suspension shown in FIGS. 15 and 16, one end portion 5a of a lower arm 5 extending in the vehicle width direction is connected to a lower portion of a wheel support member 3 that rotatably supports a wheel 1, and the lower end of the lower arm 5 extends vertically. In addition to the shock absorber 7, the coil spring 9 does not coincide with the axis Sb of the shock absorber 7 and the coil spring 9 is arranged in an inclined manner with the axis Ss eccentric to the outside in the vehicle width direction.

Further, in FIG. 15, the axial center of the upper ends of the shock absorber 7 and the coil spring 9 is made to coincide with the force application point (coupling point) Pu of the upper mount portion to which the vehicle body load Fu is applied, and the vehicle body side member is swung. While being freely connected, the axis line Ss of the coil spring 9 is connected to the vehicle body load F.
It is tilted so as to coincide with the direction in which u acts (on the line connecting the force application point Pu and the intersection Po). Further, in FIG. 16, the coil spring 9 is provided at a position independent of the force application point Pu.
Is connected to the member on the vehicle body side so as to be swingable, and is inclined so that the intersection Po may pass through the axis line Ss of the coil spring 9.

As described above, even if the force application point Pu of the vehicle body load Fu and the vehicle body ground contact center point Q are deviated in the vehicle width direction, the coil spring 9 only supports the vehicle body load Fu so that the coil spring 9 can support the shock absorber. Since it is eccentric from the axis Sb of 7, the bending moment does not occur in the shock absorber 7, and the friction of the sliding portion of the shock absorber 7 is reduced.

The above-mentioned intersection Po is the ground load Fg acting vertically upward from the wheel ground contact center Q when the suspension keeps the vehicle body in a neutral state (state in which the body posture is kept horizontal). , The tensile force F _R acting inward in the vehicle width direction along the axis S _R of the lower arm 5 and the vehicle body load Fu described above pass therethrough. On the other hand, the technique described in Japanese Utility Model Laid-Open No. 56-150603 is
The structure is such that the spring force of the coil spring that is eccentric to the axis of the strut is changed inside and outside in the vehicle body direction, and this spring force acts in a direction that cancels the bending moment generated in the strut, The moment is reduced to reduce the friction of the sliding portion of the strut.

[0007]

By the way, an active suspension for suppressing the vehicle posture by canceling the external force from the road surface or the inertial force applied to the vehicle body is also arranged between the wheel support member and the vehicle body side member. Friction easily occurs in the fluid pressure cylinder. In particular, the active suspension is controlled so as to always maintain a constant vehicle posture, so the frequency of use in the vicinity of the neutral position sliding part of the sliding part of the fluid pressure cylinder is high, and When the vehicle is traveling by using, the external force applied to the vehicle is often small both vertically and horizontally, so that the influence of friction is relatively conspicuous. Therefore, it is very important to reduce the friction only near the neutral position sliding portion.

Therefore, it is conceivable to adopt the above-mentioned friction reducing technique for this active suspension, but since this technique is a friction reducing technique on the assumption that the weight of the vehicle body is received only by the spring, it is adopted. It is not possible. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an active suspension that can reduce friction applied to a fluid pressure cylinder and improve riding comfort and steering stability.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 is such that an axis is formed between a lower portion of a wheel supporting member for rotatably supporting a wheel and a member on the vehicle body side. A lower arm swingably connected in the width direction and a lower end rigidly coupled to the wheel support member with the axis line oriented vertically, and the center axis of the upper end is swingable to the connection point of the upper mount portion. In an active suspension including a fluid pressure cylinder connected to a wheel, and a coil spring disposed between the upper mount portion and the wheel support member with its axis oriented in the up-down direction, the active suspension passes through the ground contact center point of the wheel. The intersection of the vertical line and the extension of the axis of the lower arm is an intersection, and the line connecting this intersection and the connecting point of the upper mount part is the reference line, and the vehicle width direction with respect to this reference line. Of Position and one eccentrically the fluid pressure cylinder on the side of the outside position located on the other side with respect to the reference line, axis passing through the connection point of the upper mount part, and with respect to the axis is the reference line The coil spring is eccentrically arranged so as to form a predetermined inclination angle, and a resultant force vector that combines the thrust of the fluid pressure cylinder and the spring reaction force of the coil spring is acted on the reference line so that the vehicle body is in a neutral state. So that the fluid pressure
It is characterized in that the cylinder and the coil spring share the load of the vehicle body.

Further, in the active suspension according to a second aspect of the present invention, an axis line is swingably connected between a lower portion of a wheel supporting member for rotatably supporting a wheel and a vehicle body side member in a substantially vehicle width direction. A lower arm, a fluid pressure cylinder in which a lower end portion is rigidly connected to the wheel support member with its axis oriented in the vertical direction, and an axial center of the upper end portion is swingably connected to a connecting point of the upper mount portion, and the upper mount In an active suspension including a coil spring having an axis extending vertically between the wheel support member and the wheel support member, the upper end of the coil spring is connected to the upper end of the fluid pressure cylinder. The upper mount section is swingably connected independently of the connecting point, and the intersection point of the vertical line passing through the ground contact center point of the wheel and the extension line of the lower arm axis is taken as the intersection point. The point at which the axis to each other of the fluid pressure cylinder and the coil spring intersects the axis point, when the reference line a line connecting said axis point and the intersection, the inner position and an outer position in the vehicle width direction with respect to the reference line The fluid pressure cylinder is eccentrically arranged on one side, and on the other side with respect to the reference line, the axis passes through a connecting point of the upper end portion of the coil spring , and the axis corresponds to the reference line. The coil springs are eccentrically arranged so as to form a predetermined inclination angle with respect to each other, and a resultant force vector obtained by combining the thrust force of the fluid pressure cylinder and the spring reaction force of the coil springs is applied on the reference line to To be neutral
To, is characterized in that to support the vehicle body load share, respectively Re its <br/> between said fluid pressure cylinder and the coil spring.

Furthermore, the invention according to claim 3 is the same as claim 1.
Alternatively, in the active suspension according to the second aspect, the inclination angle of the axis of the coil spring is set to be within an angle that causes the resultant force vector to act on the reference line and does not pass through the intersection.

[0012]

According to the active suspension of the first aspect of the present invention having the above structure, the vehicle load is applied from the connecting point of the upper mount portion toward the intersection on the reference line. Further, since the upper end of the coil spring is connected to the upper end of the fluid pressure cylinder at the connection point, the thrust of the fluid pressure cylinder and the spring reaction force of the coil spring act toward the connection point. Here, if the vector opposite to the vector of the vehicle body load acting on the reference line does not act, the side of the fluid pressure cylinder near the sliding part of the piston rod, especially the neutral position sliding part that is frequently used. Force is generated and friction increases.

Therefore, in the present invention, since the resultant force vector which is the combination of the thrust force and the spring reaction force is made to act on the reference line which is the vector in the direction opposite to the vector of the vehicle body load, the neutral position slide of the piston rod is performed. Almost no side force is generated near the moving part, and friction is reduced. As a result, the suspension becomes an active suspension that smoothly performs a stroke operation, so that good riding comfort and steering stability can be obtained.

Further, according to the active type suspension of the second aspect, since the upper ends of the fluid pressure cylinder and the coil spring are connected to the upper mount portion at independent connection points, respectively, the side force is fluid pressure. It occurs in the cylinder body (cylinder tube).
Therefore, the thrust of the fluid pressure cylinder, the spring reaction force of the coil spring, the ground load acting vertically upward from the ground contact center point of the wheel, and the tensile force acting along the axis of the lower arm must be balanced. Therefore, the side force cannot be reduced. Here, the vector of the ground contact load and the vector of the pulling force of the lower arm pass through the intersection.

Therefore, in the present invention, the resultant force vector obtained by combining the thrust force and the spring reaction force is made to act on the reference line passing through the intersection to maintain the balance state with other external force. Almost no side force is generated on the cylinder body, and friction is reduced.
As a result, the suspension becomes an active suspension that smoothly performs a stroke operation, so that good riding comfort and steering stability can be obtained.

According to the active suspension of the third aspect, when the coil spring is arranged eccentrically with respect to the reference line, the spring force of the coil spring acts in the direction in which the side force of the fluid pressure cylinder is reduced. To do. This makes it possible to obtain an active suspension capable of reducing friction even if the inclination arrangement of the coil springs is restricted by the restriction of the vehicle layout.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The active suspension of the present invention will be described below with reference to the drawings. 1 to 7 show a first embodiment of the active suspension.
As shown in FIG. 1, the wheel support member 12 that rotatably supports the wheel 10 and the wheel support member 1 that extends substantially in the vehicle width direction.
The lower arm 14 connected to 2 and the axial center of the upper end portion are swingably connected to the vehicle body side member via the force application point (connection point) Pu of the upper mount portion 16, and the lower end portion is connected to the wheel support member 12. A rigidly connected hydraulic cylinder (fluid pressure cylinder) 18 and an axial center of an upper end portion are swingably connected to the vehicle body side member via the force application point Pu, and the axis Ss is the axis Sa of the hydraulic cylinder 18. The coil spring 20 is arranged so as to be inclined outward in the vehicle width direction.

That is, the lower arm 14 is a link member in which a wheel side connecting point 14a and a vehicle body side connecting point 14b are formed at both ends of the axis line S _R , and the lower portion of the wheel supporting member 12 is located at the wheel side connecting point 24a. Is swingably connected to
The vehicle body side connecting point 24b is swingably connected to a vehicle body side member (not shown). Also, the hydraulic cylinder 18
Is a cylinder tube 18 arranged vertically.
The lower end of a is rigidly coupled to the wheel support member 12, and the upper end of the piston rod 18b protruding upward from the upper end of the cylinder tube 18a swings with the axis Sa coinciding with the force point Pu of the upper mount portion 16. It is freely connected. Then, a predetermined operating pressure supplied to the cylinder tube 18a generates a thrust force (actuator generated force) in the direction of the axis Sa to suppress a change in the posture of the vehicle body. Although not shown, the present device includes a pressure control valve for controlling the operating pressure supplied to the hydraulic cylinder 18 in accordance with a command value, and accelerations in the vehicle width direction, the vehicle front-rear direction, and the vehicle body vertical direction that occur in the vehicle body. An acceleration detection device for detecting,
There is provided a computing device that computes a command value for suppressing a posture change of the vehicle body according to the acceleration detection device and outputs the command value to the pressure control valve.

Further, the upper mount portion 16 is connected to the vehicle body side member 22 so that the axial center of the upper end portion of the coil spring 20 as well as the upper end portion of the piston rod 18b is swingable at the force application point Pu. FIG. 2 shows a specific structure of the upper mount section 16. In other words, the inner member 24b on the inner peripheral side of the rubber bush 24a formed in a thick ring-shaped bonded by vulcanization, the outer member 24c on the outer peripheral side of the rubber bush 24a is bonded by vulcanization, the rubber bushing
24a , the inner member 24b, and the outer member 24c are integrally structured. Then, the upper spring seat 26 is brought into contact with the lower surface of the inner member 24b, and the through holes formed in both the inner member 24b and the upper spring seat 26,
The inner member 24b is formed by inserting the male screw end of the piston rod 18b from the lower side and screwing the nut 24d to the end protruding to the inner member 24b.
Also, the upper spring seat 26 is integrally connected.
Then, the outer peripheral edge portion of the outer member 24c and the vehicle body side member 22
The outer member 24c and the vehicle body-side member 32 are integrally connected by inserting the bolt 24e from the lower side and screwing and fastening the nut 24f to the bolt 24e protruding upward.

As shown in FIG. 1, the coil spring 20 is interposed between the upper spring seat 26 and a lower spring seat 28 arranged on the outer periphery of the upper portion of the cylinder tube 18a in a compressed state. The spring reaction force Fs acts on the axis Ss. By the way, the external force applied to this device in the neutral state (the state in which the posture of the vehicle body is kept horizontal) is shown in FIG.
Shown in. In this figure, a vertical line passing through the wheel ground contact center Q is V, and a point where this vertical line V and an extension of the axis line S _R of the lower arm 14 intersect is Po (hereinafter referred to as intersection Po). . As for the external force applied to this device, the ground load Fg acts vertically upward from the wheel ground contact center Q, and the tensile force F _R acts inward in the vehicle width direction along the axis S _R of the lower arm 14, and the upper mount portion The vehicle load (static load of the vehicle body) Fu acts from the 16 force points Pu. These external force Fg, F _L, because Fu is maintained are balanced, through their external force vector intersection Po, and the vector sum is zero (0). Therefore, the vehicle body load Fu is
It acts as a vector toward the intersection Po on the reference line Sk ₁ connecting the force application point Pu and the intersection Po.

Considering the balanced state of the piston rod 18b, as shown in FIG.
On the reference line Sk ₁ from the force application point Pu to the intersection Po
Thrust force Fa of the hydraulic cylinder 18 acts as a vector toward the force application point Pu on the axis Sa, the spring reaction force Fs of the coil spring 20 acts as a vector toward the upper side of the vehicle body, and the side force. F ₁ and F ₂ act as a vector in a direction orthogonal to the axis Sa of the piston rod 18b.

Here, in order to realize the side force F ₁ = F ₂ = 0, the three forces of the vehicle body load Fu, the thrust Fa, and the spring reaction force Fs must be balanced.
In order to keep these three forces in balance, the vectors of these three forces must all pass through the force application point Pu and the vector sum must be zero (0). Therefore, in the present embodiment, the lower spring seat 28 is fixed to the cylinder tube 18a such that the center position 28a of the lower spring seat 28 is displaced to the outer side in the vehicle width direction from the reference line Sk ₁ , and the coil is attached to the lower spring seat 36. The lower end of the spring 20 is supported. As a result, the coil spring 2 of this embodiment is
0 is arranged so that the axis line Ss passing through the force application point Pu is inclined with respect to the reference line Sk ₁ by a predetermined inclination angle θ ₁ , and the spring reaction force Fs acts as a vector toward the force application point Pu on the axis line Ss. I have to.

As described above, in this apparatus, the axis line Ss of the coil spring 20 passes through the force application point Pu, and the reference line Sk
_Since the hydraulic cylinder 18 and the coil spring 20 share and support the vehicle body load Fu acting on ₁ above, the vehicle body load Fu, the thrust force Fa, and the spring reaction force Fs are three.
The balance of power is maintained. That is, as shown in FIG. 1, the vehicle body load Fu applied to the upper mount portion 16 is applied as a shared load Fu ₁ to the hydraulic cylinder 18 from the force application point Pu and is added to the coil spring 20 as a shared load Fu ₂ (Fu = Fu ₁ + Fu ₂ ).

For these shared loads Fu ₁ and Fu ₂ ,
The hydraulic cylinder 18 applies a predetermined operating pressure from the pressure control valve into the cylinder tube 18a, so that the thrust Fa having the same magnitude as the shared load Fu ₁ acts upward.
Further, the coil spring 20 is arranged so as to have a specific spring constant and the spring axis Ss has a predetermined inclination angle θ ₁ with respect to the reference line Sk ₁ , so that the shared load F
A spring reaction force Fs having the same magnitude as u ₂ acts upward.

Since the thrust Fa and the spring reaction force Fs act toward the force application point Pu, a resultant force vector ΔF (ΔF = Fa + Fs) having the same magnitude as the vehicle body load Fu, as shown in FIG. , And acts on the reference line Sk ₁ in the opposite direction to the vehicle body load Fu. As a result, the balance of the three forces of the vehicle body load Fu, the thrust Fa, and the spring reaction force Fs is maintained, and the side forces F ₁ and F ₂ acting on the piston rod 18b are zero (F ₁ = F ₂ = 0). Become.

Therefore, when the vehicle equipped with the active suspension having the above-described structure travels, the axis Ss of the coil spring 20 is set to the force application point Pu which coincides with the axis Sa of the hydraulic cylinder 18, and the thrust of the hydraulic cylinder 18 is set. Since the resultant force vector ΔF of Fa and the spring reaction force Fs of the coil spring 20 is applied in the direction toward the force application point Pu on the reference line Sk ₁ , the three forces Fu, Fa, Fs.
Therefore, almost no friction is generated in the vicinity of the neutral position of the piston rod 18b which is constantly sliding. As a result, the active suspension smoothly performs the stroke operation, so that it is possible to obtain good riding comfort and steering stability.

Further, FIG. 6 shows a side force at the time of wheel stroke, in which the active suspension of this embodiment and the conventional active suspension (device in which the axes of both the hydraulic cylinder and the coil spring are aligned) are used. It is compared by the amount of generation of. The vicinity of the neutral position of the piston rod of the active suspension is frequently used and always slides. Therefore, comparing the present embodiment with the conventional device at the normal position of the stroke amount in this figure, it is found that the active suspension of the present embodiment does not generate side force and friction is significantly reduced. Becomes clear. Note that the device of this embodiment also tends to increase the side force as the amount of bound and rebound increases, but the active suspension performs stroke operation near the normal position, so there is no effect on ride comfort and steering stability. Does not give.

FIG. 7 shows a modification of the first embodiment. In this embodiment, the coil diameter R is gradually increased from the upper end portion 32a toward the lower end portion 32b between the upper spring seat 30a and the lower spring seat 30b arranged on the outer periphery of the upper portion of the cylinder tube 18a. A coil spring 32 having a truncated cone shape is installed.

By interposing the coil spring 32 having the above structure, it is possible to prevent the expanded lower end portion 32b from interfering with the piston rod 18b, and increase the layout flexibility of the suspension. Next, FIG.
12 to 12 show the second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the upper mount portion 40 is
The upper end portions of the piston rod 18b and the coil spring 20 are swingably movable at independent positions, respectively, on the vehicle body side member 2
It is connected to 2. FIG. 9 shows a specific structure of the upper mount section 40. That is, the upper spring seat 4
An upper end portion of the coil spring 20 is swingably supported by the outer peripheral edge portion of 2 via a rubber bush 44. Further, a through hole is formed in a protruding portion 42a provided in the central portion of the upper spring seat 42, and a pair of rubber bushes 46a and 46b are arranged on the upper and lower surfaces of the protruding portion 42a so that the through hole and the bush hole correspond to each other. Of the piston rod 18b, which is provided with the washer 48a,
Insert the bush holes 6a and 46b and the through holes from below. Then, after the washer 48b is externally fitted to the tip end portion of the piston rod 18b protruding above the rubber bush 46b, the nut 50 is screwed and fastened to the tip end portion of the piston rod 18b and the upper spring seat 42.
And are swingably and integrally connected. Then, the bolt 24e is inserted from the lower side into the outer peripheral edge portion of the upper spring seat 42 and the vehicle body side member 22, and the bolt 24 protruding upward.
The upper spring seat 42 and the vehicle body side member 22 are integrally connected by screwing and fastening the nut 24f to e.

As a result, the upper ends of the piston rod 18b and the coil spring 20 are swingably connected to the vehicle body side member 22 at independent force application points (connection points) Pu ₁ and Pu ₂ as shown in FIG. To be done. The point where the axis Sa of the hydraulic cylinder 18 and the axis Ss of the coil spring 20 intersect is referred to as Pc (hereinafter referred to as the axis point Pc).

Here, considering the equilibrium state of the piston rod 18b in this apparatus, as shown in FIG. 10, the vehicle body load Fu applied to the upper mount portion 40.
Means that the first component force Fw ₁ in the vertical direction is the hydraulic cylinder 1
The second component force Fw ₂ of the vehicle body load Fu, which acts as a vector parallel to the axis Sa of 8 and is orthogonal to the first component force Fw ₁ , acts as a vector directed inward in the vehicle width direction. Further, the thrust Fa of the hydraulic cylinder 18 acts as a vector toward the force application point Pu ₁ on the axis Sa, and the side forces F ₁ and F ₂ serve as vectors in a direction orthogonal to the axis Sa of the piston rod 18b. To work. Here, the vectors of the first component force Fw ₁ and the thrust force Fa act in opposite directions to cancel each other, and the second component force Fw ₂ is
It is in balance with the side forces F ₁ and F ₂ .

As a result, the side force F ₁ = F ₂ =
In order to obtain 0, it is necessary to consider the balance state of the external force applied to this device. The external force applied to this device is as shown in Fig. 1.
As shown in FIG. 1, a ground load Fg acts vertically upward from the wheel ground contact center Q, a tensile force F _R acts inward in the vehicle width direction along the axis S _R of the lower arm 14, and the hydraulic cylinder 18 moves. Thrust Fa acts on the axis Sa, and spring reaction force Fs acts on the axis Ss of the coil spring 20,
The side forces F ₁ and F ₂ act on the cylinder tube 18a. In this figure, since the thrust Fa and the spring reaction force Fs are shown as external forces applied to the device, the directions of the vectors are opposite.

Here, in order to realize the side force F ₁ = F ₂ = 0, the resultant vector of the thrust Fa and the spring reaction force Fs and the vector of the ground load Fg and the tensile force F _R must be balanced. I won't. In order for these three force vectors to balance, they must pass through the intersection Po and the vector sum must be zero. Therefore, in the present device, as shown in FIG. 12, the axis Sa of the hydraulic cylinder 18 is
And an axial point P at which the axis Ss of the coil spring 20 intersects
c and a line connecting the intersection Po as a reference line Sk _2, and a resultant force vector of the thrust Fa and the spring reaction force Fs is ΔF (Δ
F = Fa + Fs), ground contact load Fg and tensile force F _R
In order that the resultant force vector ΔF capable of maintaining the balance with the coil acts on the reference line Sk ₂
The inclination angle θ ₂ is set, and the vehicle body is supported by the hydraulic cylinder 18 and the coil spring 20.

That is, the hydraulic cylinder 18 generates a predetermined thrust Fa by supplying a predetermined operating pressure from the pressure control valve into the cylinder tube 18a. Further, the coil spring 20 has a specific spring constant and a predetermined inclination angle θ with respect to the reference line Sk _{2 with} respect to the spring axis Ss.
_A predetermined spring reaction force Fs is generated by arranging so as to be ₂ . Thereby, the reference line Sk
_The resultant force vector ΔF acts on ₂ .

Then, the resultant force vector ΔF is the reference line Sk ₂
Since it acts on the side, a balance is maintained between the resultant force vector ΔF and the ground load Fg and the tensile force F _R, and the side force F ₁ acting on the cylinder tube 18a,
F ₂ becomes zero (F ₁ = F ₂ = 0). Therefore, when a vehicle equipped with the active suspension having the above-described structure travels, a resultant force vector ΔF of the thrust Fa of the hydraulic cylinder 18 and the spring reaction force Fs of the coil spring 20 acts on the reference line Sk ₂ to bring it into contact with the ground. Since the balance between the load Fg and the tensile force F _R is maintained, almost no friction occurs in the vicinity of the neutral position of the piston rod 18b which is constantly sliding. As a result, the active suspension smoothly performs the stroke operation, so that it is possible to obtain good riding comfort and steering stability.

Further, in this embodiment, the piston rod 18
The force point Pu _{1 at} the upper end of b and the force point Pu _{2 at} the upper end of the coil spring 20 are swingably mounted on the vehicle body side member 22 at independent positions. It is possible to change θ ₂ as appropriate within the range where the layout can be established.
This makes it possible to provide an active suspension having a high degree of freedom in design.

On the other hand, due to vehicle layout restrictions, the inclination angle θ of the coil spring 20 shown in the first and second embodiments.
_When it is impossible to take ₁ and θ ₂ , the tilt angle may be set in the range shown in FIGS. 13 and 14. That is, in the first embodiment shown in FIG. 13, the tilt angle is set within the range θa of the tilt angle from the tilt angle θ ₁ to the reference line Sk ₁ .
Within this range, the spring force of the coil spring 20 inclined with respect to the reference line Sk ₁ is equal to the piston rod 1
It acts to reduce the side forces F ₁ and F ₂ acting on 8b. Thereby, even if the arrangement of the coil springs 20 is restricted by the restriction of the vehicle layout,
Friction can be reduced.

The second embodiment shown in FIG. 14 is also set within the range θb of the tilt angle from the tilt angle θ ₂ to the reference line Sk ₂ . Within this range, the spring force of the coil spring 20 that is inclined with respect to the reference line Sk ₂ acts on the cylinder tubes 18 a to generate the side forces F ₁ and F _2.
It is possible to reduce the friction by reducing the friction.

Further, since it is possible to reduce friction by changing the inclination arrangement of the coil spring 20 within the range shown in FIGS. 13 and 14, when using an existing coil spring, the lower spring seat 28 is The friction reducing effect can be exerted only by changing the position, and thus the cost of the active suspension can be reduced.

The structure of the upper mount portions 16 and 40 shown in the first and second embodiments is not limited to the structure using the rubber bush, but may be, for example, the ball mount structure. Even with the structure, it is possible to obtain the same effect as that of each of the above-described embodiments. Further, in the structure of the upper mount portion 40 of the second embodiment, since the coil spring 20 itself bends, the same operational effect can be obtained by directly connecting to the vehicle body side member 22 without using a rubber bush or a ball joint. Obtainable.

Although not described in the operation of each of the above embodiments, the acceleration detecting device detects changes in vertical acceleration (vertical G), longitudinal acceleration (forward / backward G) and lateral acceleration (lateral G) applied to the vehicle. The arithmetic unit outputs a command value to the pressure control valve in accordance with these changes, and the hydraulic cylinder 18 is supplied with predetermined hydraulic oil under the control of the pressure control valve in accordance with the command value. Roll flat control, bounce control, which is the attitude control in the direction
Pitch control shall be performed.

In each of the above embodiments, the hydraulic active suspension has been described, but the invention is not limited to this, and an active suspension using another working fluid such as air pressure may be used.

[0044]

As described above, according to the first aspect of the present invention.
In the active suspension described above, the resultant force vector that is a combination of the thrust force of the fluid pressure cylinder and the spring reaction force of the coil spring is made to act on the reference line that is a vector in the direction opposite to the vector of the vehicle body load. Almost no side force is generated near the neutral position sliding portion of the rod, and friction can be reduced. As a result, an active suspension that smoothly performs a stroke operation is obtained, and thus good ride comfort and steering stability can be obtained.

Further, in the active suspension according to the second aspect, the resultant force vector obtained by combining the thrust of the fluid pressure cylinder and the spring reaction force of the coil spring acts on the reference line passing through the intersection, and this resultant force vector and other Since the balance with external force is maintained, almost no side force is generated in the main body of the fluid pressure cylinder, and friction can be reduced. As a result, an active suspension that smoothly performs a stroke operation is obtained, and thus good ride comfort and steering stability can be obtained. Further, according to the present invention, since the upper ends of the fluid pressure cylinder and the coil spring are connected to the upper mount portion at independent connection points, respectively, the arrangement of the coil spring may be appropriately changed within a range where the layout can be established. It becomes possible to provide an active suspension having a high degree of freedom in design.

In the active suspension according to the third aspect, when the coil spring is eccentrically arranged with respect to the reference line, the spring force of the coil spring acts in the direction in which the side force of the fluid pressure cylinder is reduced. Therefore, even if the inclination arrangement of the coil springs is limited due to the restriction of the vehicle layout, it is possible to obtain the active suspension capable of reducing the friction.

[Brief description of drawings]

FIG. 1 is a front view showing an active suspension according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an upper mount portion according to the first embodiment.

FIG. 3 is a front view showing an external force applied to the suspension according to the first embodiment, which keeps the vehicle body posture neutral.

FIG. 4 is a diagram showing a balanced state of piston rods of the fluid pressure cylinder of the first embodiment.

FIG. 5 is a diagram showing a combined vector obtained by combining the thrust force of the fluid pressure cylinder acting on the reference line of the suspension of the first embodiment and the spring reaction force of the coil spring.

FIG. 6 is a diagram showing the amount of side force generated by the active suspension of the present invention and the conventional suspension at the time of wheel stroke.

FIG. 7 is a front view showing a modification of the first embodiment.

FIG. 8 is a front view showing an active suspension according to a second embodiment of the present invention.

FIG. 9 is a diagram showing an upper mount portion according to a second embodiment.

FIG. 10 is a diagram showing a balanced state of piston rods of a fluid pressure cylinder of a second embodiment.

FIG. 11 is a front view showing an external force applied to the suspension of the second embodiment, which maintains the vehicle body posture in a neutral state.

FIG. 12 is a diagram showing a combined vector that combines the thrust of the fluid pressure cylinder acting on the reference line of the suspension of the second embodiment and the spring reaction force of the coil spring.

FIG. 13 is a front view showing the range of the inclined arrangement of the coil springs in the first embodiment.

FIG. 14 is a front view showing the range of the inclination arrangement of the coil spring in the second embodiment.

FIG. 15 is a front view showing a first example of a conventional strut suspension.

FIG. 16 is a front view showing a second example of a conventional strut suspension.

[Explanation of symbols]

10 Wheel 12 Wheel Support Member 14 Lower Arm 16, 40 Upper Mount Part 18 Fluid Pressure Cylinder 18a Fluid Pressure Cylinder Body (Cylinder Tube) 18b Fluid Pressure Cylinder Rod 20 Coil Spring Fa Fluid Pressure Cylinder Thrust Fs Coil Spring Counter Force ΔF Combined force vector Pc Axial point Po Intersection Pu Pu Connection part of upper mount part where upper ends of fluid pressure cylinder and coil spring are connected on the same axis Pu ₁ Connection part Pu of upper mount part where upper end of fluid pressure cylinder is connected ₂ Connection part of upper mount part where upper ends of coil springs are connected on the same axis Q Wheel ground contact center points Sk ₁ and Sk ₂ Reference line V Vertical line Sa Fluid cylinder axis Ss Coil spring axis S _R Lower arm Axis θ ₁ , θ ₂ Tilt angle

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60G 3/18 B60G 3/28 B60G 11/14-11/16 B60G 11/56-11/58 B60G 15 / 06

Claims (3)

(57) [Claims] 1. A lower arm having an axial line swingably connected between a lower portion of a wheel support member for rotatably supporting a wheel and a vehicle body-side member, and an axial line extending vertically. A fluid pressure cylinder having a lower end rigidly coupled to the wheel support member and having an axial center of the upper end swingably connected to a connection point of the upper mount portion, and between the upper mount portion and the wheel support member. In an active suspension including a coil spring arranged with its axis oriented in the vertical direction, an intersection point is defined as an intersection point of a vertical line passing through the ground contact center point of the wheel and an extension line of the axis line of the lower arm. When the line connecting the said connecting point of said the intersection upper mount portion and a reference line, arranged eccentrically the fluid pressure cylinder on one side of the inner position and an outer position in the vehicle width direction with respect to the reference line, On the other side of the reference line, the coil spring is eccentrically arranged so that the axis passes through the connection point of the upper mount portion and the axis forms a predetermined inclination angle with respect to the reference line, and the fluid and thrust of pressure cylinders, the combined resultant force vector and a spring reaction force of the coil spring is acting on the reference line, the middle vehicle body
The fluid pressure cylinder and the coil so that they are in an upright state.
An active suspension characterized by supporting the vehicle load by sharing with the spring . 2. A lower arm having an axial line swingably connected between a lower portion of a wheel support member for rotatably supporting a wheel and a vehicle body side member, and an axial line extending vertically. A fluid pressure cylinder having a lower end rigidly coupled to the wheel support member and having an axial center of the upper end swingably connected to a connection point of the upper mount portion, and between the upper mount portion and the wheel support member. In an active suspension including a coil spring having an axis oriented vertically, an upper end portion of the coil spring is independent of a connecting point of an upper mount portion to which an upper end portion of the fluid pressure cylinder is connected. Is connected to the wheel so that the vertical line passing through the ground contact center point of the wheel and the extension line of the axis of the lower arm intersect, and the intersection of the fluid pressure cylinder and the coil spring The point at which line each other intersects an axis point, when the reference line a line connecting said axis point and the intersection, the fluid pressure cylinder on one side of the inner position and an outer position in the vehicle width direction with respect to the reference line Is eccentrically arranged, and on the other side of the reference line, the axis is the upper end of the coil spring
The coil spring is arranged so as to be eccentric so that the axis passes through the connection point of the section and forms a predetermined inclination angle with respect to the reference line, and the thrust of the fluid pressure cylinder and the spring reaction force of the coil spring. The resultant force vector, which is a combination of and, is applied to the reference line so that the vehicle body becomes neutral.
As described above , the active suspension characterized in that the fluid pressure cylinder and the coil spring share the load of the vehicle body. 3. The inclination angle of the axis line of the coil spring is set within a range of an angle within which the resultant force vector acts on the reference line and which does not pass through the intersection. Alternatively, the active suspension according to item 2.