JPH06312613A - Suspension - Google Patents

Abstract

PURPOSE:To stabilize the attitude of a vehicle at the turning time and braking time by displacing the king pin of a wheel at the braking time during turning so as to change the toe angle of the wheel in the appropriate direction, thereby preventing the vehicle from being sort of over-steered. CONSTITUTION:Bushes 14a, 16a for connecting the base end parts of the rear links 14b, 16b of an upper and a lower arms 14, 16 to a body 18 are fitted in the longitudinally movable state and driven through hydraulic cylinders 22, 24. The hydraulic cylinders 22, 24 supply oil pressure, pressurized by pumps 22b, 24b, through solenoid changeover valves 22a, 24a. The hydraulic cylinders 22, 24 are expansion-driven to change the positions of intersections P, Q, obtained by extending the rear links 14b, 16b and front links 14a, 16a, in the vehicle width direction so as to change the inclination of a king pin. The solenoid changeover valves 22a, 24a and the pumps 22b, 24b are driven by control signals outputted from a microcomputer 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle suspension.

[0002]

2. Description of the Related Art The body of an automobile is suspended from a wheel via a suspension, and the suspension determines the riding comfort and running performance of the automobile. The wheels are attached to the vehicle body with an inclination called wheel alignment, and the alignment determines the stability during traveling and the cornering characteristics during turning. The alignment is determined by the tilt angle of the kingpin axis, the camber angle, the caster angle, the toe angle, etc.

By the way, it is generally known that a conventional vehicle can maintain a stable vehicle attitude by directing the toe angles of the wheels inward (toe-in direction) when braking in a straight traveling state. On the other hand, various proposals have been made in the past to improve the stability of the vehicle while it is turning. For example, Japanese Patent Publication No. 3-59846 discloses that electronic control is used to prevent roll during turning. Disclosed is such a suspension.

[0004]

However, in such a conventional suspension, when braking in a turning state, particularly in a vehicle with a tendency to oversteer, even if the vehicle body is simply prevented from rolling, the vehicle is unstable due to spin. Behavior is easy to occur. In order to suppress this unstable behavior, it is desirable to make the steering understeer.

By the way, in order to achieve understeer during braking during turning, the wheels on the outer wheel side are directed in the toe-out direction and the wheels on the inner wheel side are directed in the toe-in direction during turning. It was found by the inventors of the present application that this can be done. However, in conventional suspensions, the compliance steer setting is generally made so that the outer wheel is directed in the toe-in direction due to the action of lateral force during turning, which makes it difficult to obtain the understeer characteristic during the braking. Thus, there is a problem that spin is apt to occur during sudden braking.

In view of such conventional problems, the present invention, when braking during turning, displaces the kingpin axis of the wheel to change the toe angle of the wheel in an appropriate direction, thereby causing the vehicle to oversteer. It is an object of the present invention to provide a suspension which is prevented to stabilize the posture during turning and braking of the vehicle.

[0007]

In order to achieve such an object, in the first configuration of the present invention, the vehicle turning detection means for detecting that the vehicle is in a turning state and the kingpin offset amount of the wheels are set. And a means for changing the kingpin offset amount changing means and, when detecting that the vehicle is in a turning state, operating the kingpin offset amount changing means to increase the kingpin offset on the outer wheel side in the positive direction. To do.

Further, in the first structure, it is desirable that the kingpin offset amount changing means is constituted as a mechanism for changing the tilt angle of the kingpin shaft.

Further, the kingpin offset amount changing means can be constructed as a mechanism for moving the kingpin shaft in parallel in the vehicle width direction.

In the first configuration, the executing means may be configured to control the wheel center / king pin offset amount to approach zero.

Further, the executing means is a wheel center
The kingpin offset amount can be increased.

Furthermore, the executing means is configured to control the amount of change in the kingpin offset in accordance with the turning amount detected by the vehicle turning detection means.

In order to achieve such an object, in the second structure of the present invention, vehicle turning detection means for detecting that the vehicle is in a turning state, and tread changing means for changing the tread of the wheels. And executing means for activating the tread changing means according to the turning amount of the vehicle when it is detected that the vehicle is in a turning state.

Further, in order to achieve the above object, in the third structure of the present invention, vehicle turning detection means for detecting that the vehicle is in a turning state, and kingpin offset for changing the kingpin offset amount of the wheels. Amount changing means, tread changing means for changing the tread of the wheel,
And a executing means for operating the tread changing means while operating the kingpin offset amount changing means to increase the kingpin offset on the outer wheel side in the positive direction when detecting that the vehicle is in a turning state.

[0015]

In the first structure of the suspension according to the present invention having the above-described structure, when it is detected that the vehicle is in a turning state, the executing means actuates the kingpin offset amount changing means to set the outer wheel side. Since the kingpin offset is increased in the positive direction, it is possible to suppress the tendency of the outer wheel to toe-in during turning and to make the cornering steer understeer, thereby improving the vehicle body stability during turning. Also, when braking force is generated in the tire due to friction with the road surface when braking during turning, the outer wheel can be changed in the toe-out direction by the moment generated by the kingpin offset and the braking force increased in the positive direction,
Since understeering can be further increased during this braking, the vehicle body can be prevented from spinning even by sudden braking and the posture can be stabilized.

Further, by configuring the kingpin offset amount changing means in the first structure as a mechanism for changing the tilt angle of the kingpin shaft, the kingpin offset amount can be easily changed by changing the tilt angle of the kingpin shaft. .

Further, since the kingpin offset amount changing means is constituted as a mechanism for moving the kingpin shaft in parallel in the vehicle width direction, the kingpin offset amount can be easily changed by the parallel movement of the kingpin shaft.

The executing means is a wheel center
By making the control so that the kingpin offset amount approaches zero, it is possible to lighten the steering wheel operation, reduce the influence of disturbance input from the road surface via the wheels, and significantly improve drivability at low speed running. You can

Further, the executing means is a wheel center
By increasing the kingpin offset amount, the steering holding force of the steering wheel can be increased and the stability at high speed can be further improved.

Furthermore, the executing means is configured to control the amount of change in the kingpin offset in accordance with the turning amount detected by the vehicle turning detection means, so that the outer wheel can direct the toe-out more than necessary during braking. Can be prevented and the steered state corresponding to the turning amount can be maintained.

According to the second aspect of the present invention, when it is detected that the vehicle is in a turning state, the executing means operates the tread changing means to change the tread according to the turning amount of the vehicle. As a result, the lateral force can be quickly generated on the ground contact surface of the tire due to this tread change, and cornering force can be generated by this lateral force to stabilize the vehicle.

Further, in the third structure of the present invention, when it is detected that the vehicle is in a turning state, the executing means operates the kingpin offset amount changing means to set the kingpin offset on the outer wheel side in the forward direction. As the tread changing means is activated, the outer ring is changed to the toe-out direction by the moment generated by the braking force to cause an understeer, and the tread changing means can quickly generate the cornering force. , The toe-out change due to the kingpin offset change can be performed early to further improve the stability of the vehicle body.

[0023]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 1 to 11 show an embodiment of a suspension according to the present invention. FIG. 1 is a schematic view showing the front suspension 10 and the rear suspension 10a as viewed from the front, respectively, and FIG. FIG. 3 is a schematic plan view of the rear suspension 10a, FIG. 4 is a system diagram for controlling the suspension of this embodiment, and FIG. 5 is an explanatory view of the ground contact state of the wheels of the front suspension 10 as seen from the front side. FIG. 6 is an explanatory view of the wheels of the front suspension 10 as seen from the bottom side, and FIG. 7 is an explanatory view of the wheels of the rear suspension as seen from the bottom side.
Is a change characteristic diagram of the kingpin axis inclination angle of the inner and outer wheels of the front suspension 10 during turning, FIG. 9 is a change characteristic diagram of the kingpin offset amount of the inner and outer wheels of the front suspension 10 during turning, and FIG. 10 is a unit of the rear suspension 10. FIG. 11 is a characteristic diagram showing the tread change amount per unit time, and FIG. 11 is a change characteristic diagram of the wheel center / king pin offset amount on the outer wheel side when the front suspension 10 turns.

That is, as shown in FIGS. 1 and 2, the front suspension 10 according to the present embodiment has front wheels 1 as steering wheels.
2 is connected to a vehicle body 18 via an upper arm 14 and a lower arm 16. The upper and lower arms 1
Reference numerals 4 and 16 are C-shaped front links 14a and 16a and rear links 14 that are arranged outside the vehicle body and have a narrowed tip.
5 and 16b, a straight line connecting the rotation centers O1 and O2 of the upper arm 14 and the lower arm 16 as shown in FIG. 5 is a kingpin axis (hereinafter referred to as KP axis) 20.
Becomes The upper part of the KP shaft 20 is normally inclined inward of the vehicle,
The KP axis tilt angle is determined by the angle θ formed by the vertical line of the road surface E. The kingpin offset is determined by the distance L1 between the point S where the extension of the KP shaft 20 intersects the road surface E and the ground contact point T at the center of the front wheel 12 in the width direction. When the kingpin offset exists inside the vehicle, it is a positive direction, and when it exists outside the vehicle, it is a negative direction. Further, the front wheel 12
The wheel center kingpin offset is determined by the distance L2 provided between the KP shaft 20 and the center of the front wheel 12 on the center axis of the wheel.

In the front suspension 10, as shown in FIG. 2, bushes 14c and 16c for connecting the rear links 14b and 16b of the upper and lower arms 14 and 16 to the vehicle body 18 are attached so as to be movable back and forth. By driving the bushes 14a, 16a via hydraulic cylinders 22, 24 as actuators, a kingpin offset amount changing means 26 is configured. The hydraulic cylinders 22 and 24 are electromagnetic switching valves 22a and 24.
The hydraulic pressure pressurized by the pumps 22b and 24b is supplied via a, and the switching of the electromagnetic switching valves 22a and 24a causes the piston rods of the hydraulic cylinders 22 and 24 to expand and contract to move the bushes 14a and 16a back and forth.

Therefore, when the hydraulic cylinders 22 and 24 are expanded and contracted, the rear links 14b and 16 are moved.
The horizontal inclination angle of b is changed, and this rear link 14
It is possible to change the positions of the intersections P and Q, which are extensions of b and 16b and the front links 14a and 16a, in the vehicle width direction. That is, the intersection P of the front and rear links 14a and 14b of the upper arm 14 and the lower arm 1
The straight line connecting the intersection Q of the front and rear links 16a and 16b of 6 serves as the KP axis 20.
By moving Q, the tilt angle θ of the KP shaft 20 can be changed, and the KP shaft 20 itself can be translated.

The electromagnetic switching valves 22a, 24a and the pumps 22b, 24b are driven by a control signal output from a microcomputer 28 as an executing means, and the movement amount of the bushes 14a, 16a is controlled. As shown in FIG. 4, the microcomputer 28 includes a vehicle speed (V) signal, a steering angle (θH) signal, a steering speed (θH dot) signal, a yaw rate (ψ dot) signal, a lateral acceleration (G) signal, The stroke signal of the shock absorber and the ground clearance (X) signals are input, and the control signals for the electromagnetic switching valves 22a and 24a and the pumps 22b and 24b are determined based on these signals.

On the other hand, the rear suspension 10a is
As shown in FIGS. 1 and 3, the rear wheel 30, which is a driven wheel, is attached to the vehicle body 18 via the upper and lower arms 32 and 34, similarly to the front wheel 12. The tip end portions of the upper and lower arms 32 and 34 arranged outside the vehicle body are attached to a spindle 36 that rotatably supports the rear wheel 30, and the base end portions arranged inside the vehicle are relative to the vehicle body 18. And is attached to a gusset 38 that is movable in the vehicle width direction.

The tread changing means 42 is constructed by attaching the gusset 38 to the vehicle body 18 via the hydraulic cylinder 40 as an actuator.
The hydraulic cylinder 40 is connected to the pump 4 via the electromagnetic switching valve 40a.
The hydraulic pressure pressurized at 0b is supplied to the electromagnetic switching valve 40.
By switching a, the piston rod of the hydraulic cylinder 40 expands and contracts to move the gusset 38 back and forth. The electromagnetic switching valve 40a and the pump 40b are driven by a control signal output from the microcomputer 28.

Therefore, by driving the hydraulic cylinder 40 to expand and contract, the gusset 38 can move the rear wheel 30 together with the upper and lower arms 32, 34 in the vehicle width direction, and the tread of the rear wheel 30 is thereby moved. Can be changed.

By the way, the microcomputer 28
Is the vehicle speed (V) signal, steering angle (θH) signal, steering speed (θ
It has been described above that the H dot signal, the yaw rate (ψ dot) signal, the lateral acceleration (G) signal, the shock absorber stroke signal, and the ground clearance (X) signal are input. A circuit forming the turning detection means is built in, and the vehicle turning detection means is adapted to judge the turning state of the vehicle based on any one of the signals. That is, as a signal for detecting the turning state of the vehicle, there is a method of detecting using the vehicle speed and the steering angle, and a method of detecting using lateral acceleration. There is a method of detection using. Therefore, the vehicle turning detection means can be composed of a vehicle speed sensor and a steering angle sensor, a lateral G sensor, and further a vehicle height sensor and a vehicle height sensor. .

In the front suspension 10 of this embodiment having the above structure, first, when the vehicle turning detection means determines that the vehicle is turning, a drive signal is output to the electromagnetic switching valves 22a and 24a. The hydraulic cylinders 22 and 24 are driven to expand and contract. Then, the angles of the rear links 14a and 16a of the upper and lower arms 14 and 16 change, and the KP shaft 20 can be moved.

FIG. 8 is a characteristic diagram when the tilt angle θ of the KP shaft 20 of the front wheel 12 which becomes the inner wheel and the outer wheel during turning is changed. The inner wheel shortens the hydraulic cylinder 22 and the front and rear links 14a of the upper arm 14 are made. , 14b intersection Q
The hydraulic cylinder 24 and the front and rear links 16a of the lower arm 16,
By pushing the intersection P of 16b to the outside of the vehicle body, the KP shaft 20 is moved in the tilting direction to increase the tilt angle θ. The outer ring extends the hydraulic cylinder 22 to extend the upper arm 14
The front and rear links 16a and 16b of the lower arm 16 are shortened by pushing the intersection Q of the front and rear links 14a and 14b of the lower arm 16 to the outside of the vehicle body and shortening the hydraulic cylinder 24.
By pulling in the intersection point P inward of the vehicle body, the KP shaft 20 is moved in the upright direction to reduce the inclination angle θ.

Therefore, as the tilt angle θ of the inner ring is increased and the tilt angle θ of the outer ring is decreased, the kingpin offset L1 of the inner ring moves in the negative direction and the kingpin offset L1 of the outer ring as shown in the characteristic diagram of FIG. Moves in the positive direction. Therefore, when the vehicle turns, the tendency of the outer wheels to toe-in is suppressed, while the tendency of the inner wheels to toe-in is strengthened, whereby the cornering steer can be made understeer.

Further, the toe angle of the front wheel 12 during braking can be changed by changing the kingpin offset L1 of the inner and outer wheels in this way. For example,
When the braking force R acts on the front wheels 12 as shown in FIG. 6 at the outer wheels, the toe angle of the front wheels 12 is changed around the point S where the KP shaft 20 intersects the road surface E, but the kingpin offset L1 is changed in the positive direction. Since the vehicle is moving, the moment M of the braking force R centering on the intersection point S is increased and the front wheel 12 is changed in the toe-out direction. Although illustration of the inner wheel is omitted, since the kingpin offset L1 is moving in the negative direction contrary to the outer wheel, a moment M in the opposite direction acts on the braking force R and the front wheel 12 changes in the toe-in direction. To be done.
Therefore, the toe-out of the outer wheel can be strengthened when braking is applied during turning, and the understeer tendency can be increased to prevent unstable vehicle behavior such as spin.

The movement of the KP shaft 20 has been disclosed as changing the tilt angle θ, but the present invention is not limited to this, and the hydraulic cylinders 22 and 24 are expanded and contracted in the same direction to move the KP shaft 20 in parallel. Also, the kingpin offset L1 can be changed.

On the other hand, when the turning state is detected by the vehicle turning detection means, the rear suspension 10a outputs a drive signal to the electromagnetic switching valve 40a to extend the hydraulic cylinder 40 to momentarily move the rear wheel 30 outward. And tread is changed as shown in FIG. FIG. 7 shows the effect when the tread of the outer wheel is changed, and a slip angle α is instantaneously generated due to the relationship between the vector speed U in the pushing direction and the vehicle speed V, and the lateral force is quickly generated by this slip angle α. The vehicle stability during cornering can be achieved at an early stage. For example, in this embodiment, the KP shaft 20 of the front suspension 10 is moved during turning, but the rear wheel 30
By increasing the generation of the lateral force, the understeer tendency due to the change in the toe angle of the front wheel 12 can be increased, and the stability at the time of turning can be further improved.

By the way, the front suspension 1
KP by driving the hydraulic cylinders 22 and 24 of 0
Although it has been described that the shaft 20 is moved and the kingpin offset L1 is changed, the wheel center / kingpin offset L2 can be similarly changed by moving the KP shaft 20. FIG. 11 shows a change characteristic of the wheel center / king pin offset L2 of the front wheel 12, and as shown by the characteristic A in FIG. 11, the wheel center / king pin offset amount is controlled to approach zero so that the steering wheel is operated. In addition to being light, it is possible to reduce the influence of disturbance input from the road surface through the wheels, and it is possible to remarkably improve drivability during low-speed traveling. Further, as shown in the characteristic B, the wheel center / king pin offset amount is increased so that the steering holding force of the steering wheel can be increased and the stability during high speed traveling can be further improved.

In the present embodiment, the kingpin offset amount changing means is applied to the front suspension 10 and the tread changing means is applied to the rear suspension 10a. However, depending on the steer characteristic of the vehicle itself, these kingpins may be used. The offset amount changing means and the tread changing means can be applied to both the front and rear suspensions.

[0040]

As described above, in the suspension according to claim 1 of the present invention, when it is detected that the vehicle is in a turning state, the executing means actuates the kingpin offset amount changing means and the outer ring. Since the kingpin offset on the side is increased in the positive direction, it is possible to suppress the tendency of the outer wheels to toe-in during turning and to make the cornering steer understeer, thereby improving the vehicle body stability during turning. Further, when braking during turning, the outer wheel can be changed in the toe-out direction by the moment generated by the kingpin offset and the braking force increased in the positive direction, and understeering can be further increased during this braking. Also, the vehicle body can be prevented from spinning and the posture can be stabilized.

According to the second aspect of the present invention, the kingpin offset amount changing means is constituted as a mechanism for changing the tilt angle of the kingpin shaft. Therefore, the kingpin offset amount can be easily changed by changing the tilt angle of the kingpin shaft. can do.

Further, according to claim 3 of the present invention, the kingpin offset amount changing means is constituted as a mechanism for moving the kingpin shaft in parallel in the vehicle width direction. You can change the amount.

Further, according to the fourth aspect of the present invention, since the executing means is configured to control the wheel center / king pin offset amount to be close to zero, the steering wheel operation can be lightened and the road surface can be passed through the wheels. It is possible to reduce the influence of externally input disturbances and significantly improve drivability during low-speed traveling.

Further, according to the fifth aspect of the present invention, since the executing means is configured to increase the wheel center / king pin offset amount, the steering holding force of the steering wheel is increased to further improve the stability during high speed running. Can be increased.

Furthermore, according to claim 6 of the present invention,
Since the executing means is configured to control the amount of change in the kingpin offset in accordance with the turning amount detected by the vehicle turning detecting means, it is possible to prevent the outer wheel from pointing more than necessary at the toe-out during braking, and to change the turning amount. It is possible to maintain the steered state according to.

According to a seventh aspect of the present invention, tread changing means for changing the tread of the wheel is provided, and when the vehicle turning detection means detects that the vehicle is in a turning state, the executing means causes the vehicle to turn. Since the tread changing means is activated according to the amount of turning, lateral force can be quickly generated on the contact surface of the tire due to this tread change, and cornering force is generated by this lateral force to stabilize the vehicle. Can be planned.

Further, in the third structure of the present invention, the kingpin offset amount changing means for changing the kingpin offset amount of the wheel and the tread changing means for changing the tread of the wheel are provided, and the vehicle turning detection means is provided. When it is detected that the vehicle is in a turning state, the executing means activates the kingpin offset amount changing means to increase the kingpin offset on the outer wheel side in the positive direction and the tread changing means. The moment generated by the power causes the outer ring to change in the toe-out direction to create an understeer feeling, and the tread changing means can quickly generate cornering force, so the toe-out change by changing the kingpin offset can be performed early to stabilize the vehicle body. Each that can be improved It exhibits an excellent effect.

[Brief description of drawings]

FIG. 1 is a schematic view showing one embodiment of a suspension according to the present invention, showing a front suspension and a rear suspension as viewed from the front direction.

FIG. 2 is a schematic plan view of a front suspension showing an embodiment of the present invention.

FIG. 3 is a rear suspension 1 showing an embodiment of the present invention.
It is a schematic plan view of 0a.

FIG. 4 is a system diagram for controlling a suspension according to an embodiment of the present invention.

FIG. 5 is an explanatory view showing a grounding state of wheels of a front suspension viewed from the front direction according to the embodiment of the present invention.

FIG. 6 is an explanatory view showing a ground contact state of wheels of a front suspension viewed from a bottom surface direction according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a ground contact state of a wheel of a rear suspension showing one embodiment of the present invention, as viewed from a bottom surface direction.

FIG. 8 is a change characteristic diagram of the kingpin shaft tilt angle of the inner and outer wheels of the front suspension during turning according to the embodiment of the present invention.

FIG. 9 is a change characteristic diagram of the kingpin offset amounts of the inner and outer wheels when the front suspension turns according to the embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a tread change amount per unit time of the rear suspension showing the embodiment of the present invention.

FIG. 11 is a change characteristic diagram of the wheel center / king pin offset amount on the outer wheel side during turning of the front suspension according to the embodiment of the present invention.

[Explanation of symbols]

10 Front Suspension 10a Rear Suspension 12 Front Wheel 14 Upper Arm 16 Lower Arm 18 Car Body 20 King Pin Shaft 22, 24 Hydraulic Cylinder 26 King Pin Offset Changing Means 28 Microcomputer (Execution Means) 30 Rear Wheel 32 Upper Arm 34 Lower Arm 40 Hydraulic Cylinder 42 Tread Changing Means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Ushio, 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Takao Imada 3-3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Corporation Within

Claims (8)

[Claims] 1. A vehicle turning detection means for detecting that the vehicle is in a turning state, a kingpin offset amount changing means for changing a kingpin offset amount of wheels, and a kingpin offset when it is detected that the vehicle is in a turning state. A suspension comprising: an amount changing unit that operates to increase the kingpin offset on the outer ring side in the positive direction. 2. The suspension according to claim 1, wherein the kingpin offset amount changing means is a mechanism that changes a tilt angle of the kingpin shaft. 3. The suspension according to claim 1, wherein the kingpin offset amount changing means is a mechanism for moving the kingpin shaft in parallel in the vehicle width direction. 4. The suspension according to claim 1, wherein the executing means controls the wheel center / king pin offset amount to approach zero. 5. The execution means increases the wheel center / king pin offset amount.
Suspension described in. 6. The suspension according to claim 1, wherein the executing means controls the amount of change in the kingpin offset according to the turning amount detected by the vehicle turning detection means. 7. A vehicle turning detection means for detecting that the vehicle is in a turning state, a tread changing means for changing a tread of a wheel, and a vehicle turning amount when detecting that the vehicle is in a turning state. A suspension comprising: an execution unit that operates a tread changing unit. 8. A vehicle turning detection means for detecting that the vehicle is in a turning state, a kingpin offset amount changing means for changing a kingpin offset amount of a wheel, a tread changing means for changing a tread of a wheel, and a vehicle turning. And a executing means for operating the tread changing means while increasing the kingpin offset on the outer wheel side in the positive direction by operating the kingpin offset amount changing means when it is detected that the vehicle is in a state of being suspended. .