JPH043328B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a suspension control device for a vehicle. (Prior Art) Fluid-filled bushes are provided at both ends of a suspension link such as a radius slot that constitutes the suspension of a vehicle. (Problem to be solved by the invention) In such a fluid-filled bushing, if the spring constant in the longitudinal direction of the vehicle body is set to a large value, the response during steering operation is good, but the riding comfort is slightly sacrificed, and conversely, the spring constant If it is set to a small value, the ride quality is good, but there is a large response delay during steering operation, and depending on the suspension type, the toe change becomes large. Therefore, it is conceivable to simultaneously variably control the spring constants of both fluid-filled bushes in the longitudinal direction of the vehicle body in two stages, large and small, by controlling the fluid pressure. An object of the present invention is to provide a steering wheel in a vehicle in which the spring constant of fluid-filled bushes provided at both ends of a suspension link in the longitudinal direction of the vehicle body is simultaneously variably controlled in two or more stages of large and small by controlling fluid pressure. The spring constant of the fluid-filled bushings at both ends of the suspension link can be automatically and variably controlled at the same time in accordance with changes in driving conditions and road surface conditions based on steering operation and braking conditions. To provide a suspension control device in which a spring constant is increased with emphasis on steering stability even when driving on a relatively bad road surface. (Means for Solving the Problems) In order to solve the above-mentioned problems and achieve the objects, the present invention has a suspension link extending in the longitudinal direction of the vehicle body, and a fluid seal provided at the front and rear ends of the suspension link. A suspension control device for a vehicle, comprising a bushing, and capable of simultaneously variable controlling the spring constant of both fluid-filled bushings in the longitudinal direction of the vehicle body in two or more stages, large and small, by controlling fluid pressure, A sensor that detects the steering operation state, a sensor that detects the brake state, and a processing circuit that inputs signals from the vertical vibration acceleration sensor of the vehicle body and outputs a signal of acceleration near the sprung resonance frequency of the vehicle body; a control circuit that inputs various signals and outputs signals of two or more stages according to driving and road surface conditions; an actuator for automatically and simultaneously switching the spring constants of both the fluid-filled bushings, the actuator being capable of communicating and blocking a fluid passage connecting the fluid chamber that shrinks and deforms with the fluid chamber that expands and deforms with the action of force; The present invention is characterized in that, when any of the species detection signals is detected, the spring constants of the two fluid-filled bushes are automatically variably controlled to a larger value by the actuator. (Embodiment) A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 5 is a perspective view showing an example of a suspension type, in which reference numeral 51 is a hub, 52 is a lower arm, 53 is a damper, and 54 is a radius rod. At the front and rear ends of the radius rod 54 are fluid-filled bushings 31, 41 as shown in FIG. will be provided. Both bushes 31 and 41 have inner cylinders 32 and 42 into which support pins on the vehicle body side or the nuticle side are inserted, and outer cylinders 33 and 42 which are fixed to the front and rear ends of the radius rod 54, respectively.
43 with radial rubber walls 34, 44,
As a result, fluid chambers 35, 36, 4 are located between the inner and outer cylinders 32, 33, 42, 43 in the longitudinal direction of the vehicle body.
5,46. Both bushes 31 and 41 are provided with a passage 25 that communicates with the front fluid chambers 35 and 45 and a passage 26 that communicates with the rear fluid chambers 36 and 46, and a switching valve 21 that opens and closes both passages 25 and 26 at the same time. will be established. The switching valve 21 is operated by solenoids 22 and 23. When one solenoid 22 is energized, the passages 25 and 26 are opened as shown in the figure, and when the other solenoid 23 is energized, the passages 25 and 26 are closed. FIG. 2 shows a free state in which no external force acts on the radius rod 54. FIG. 3 shows a state in which a tensile force is applied to the radius rod 54. In this case, if the passages 25 and 26 are in the open state as shown, the passage 25 is passed from the front fluid chamber 35 of the front bushing 31 to which an external force is applied. As a result, fluid flows into the front fluid chamber 45 of the rear bushing 41 and from the rear fluid chamber 46 of the rear bushing 41 to the passage 2.
5 to the rear fluid chamber 36 of the front bushing 31. Therefore, the spring constant in the longitudinal direction of the vehicle body is small. Conversely, when the solenoid 23 is energized to block the passages 25 and 26, the flow of liquid is blocked and the spring constant in the longitudinal direction of the vehicle increases. FIG. 4 shows a state in which compressive force is applied to the radius rod 54, and the flow of liquid is opposite to that in FIG. 3. Next, the control circuit will be explained based on FIG. 1 is a sensor that detects vertical vibration acceleration |G| of the vehicle body corresponding to changes in road surface conditions and vehicle speed (hereinafter referred to as G sensor), 2 is a sensor that detects steering angle |S| (hereinafter referred to as S sensor), and 3 is a brake This is a sensor (hereinafter referred to as B sensor) that detects the ON/OFF state of the switch. The output signal |G| from the G sensor 1 is input to a bandpass filter 4, which outputs a signal Gf with a frequency component near the sprung resonance frequency of the vehicle body, which is input to a comparator 5, and this output signal Gf is generated. When the predetermined value Gf is greater than or equal to ₁ , the signal is set to [1], and when it is less than the set value, the signal is set to [0], and is input to the delay circuit 6.
This input signal is provided with a certain delay time and is input to the OR circuit 8 of the logic circuit 7. Here, the delay circuit 6 is provided to delay the road surface with joints. The output signal from the S sensor 2 |S| is set to a certain predetermined value |S ₁ 1], the OFF state is set to the signal [0], and both of these signals are input to the OR circuit 8. Then, a signal [H] representing the spring constant [large] is output to the output terminal of the OR circuit 8, and when this signal [H] is output, it passes through the timer 13 to the path 2.
By energizing the solenoid 23 that closes the valves 5 and 26, the spring constants of both the fluid-filled bushes 31 and 41 are automatically controlled to [large]. Also, the signal from the OR circuit 8 is branched and input to the NOT circuit 9, and a signal [L] representing the spring constant [small] is output to the output terminal of this NOT circuit 9, and this signal [L] is output. When this happens, the solenoid 22 that opens the passages 25 and 26 is energized to automatically control the spring constant to be small. In the above, the signal Gf of the frequency component near the sprung resonance frequency of the vehicle body is greater than or equal to the set value Gf ₁ , the steering angle signal |S| is greater than or equal to the set value |S ₁ |, and the brake signal B is in the ON state. Also, the output signal of the logic circuit 7 is set to [H]. The truth table is shown below along with the road surface and driving conditions, that is, the environmental conditions.

[Table] Next, each environmental condition will be explained. First, in condition 1, the vehicle is traveling straight on a relatively good road surface with almost no undulations, and since there are no brakes, the spring constant of the front and rear bushings 31 and 41 in the longitudinal direction of the vehicle body is set to [small] with emphasis on ride comfort. . Condition 2 is when you are driving on a relatively bad road surface with large undulations, condition 3 is when you are cornering, and condition 4 is when you are braking.
In either case, the spring constant is set to [large] with emphasis on maneuverability.
Make it. In addition, in the fluid-filled bushing device, the switching valve is further provided with multiple sets of channels with different flow channel areas, and the spring constant is controlled in multiple stages by a mechanically actuated actuator or the like, so that the number of stages in which the spring constant can be varied is three or more stages. is also possible. (Effects of the Invention) As described above, according to the suspension control device of the present invention, signals from the steering sensor, the brake sensor, and the vertical vibration acceleration sensor of the vehicle body are inputted to calculate acceleration near the sprung mass resonance frequency of the vehicle body. A processing circuit that outputs signals of An actuator that simultaneously switches the spring constant in the longitudinal direction of the vehicle body to two or more levels (large and small) by controlling fluid pressure. The spring constant of the enclosed bushing in the longitudinal direction of the vehicle body can be automatically and variably controlled at the same time.
Particularly, the spring constant can be automatically controlled to a larger value with emphasis on steering stability in any of the following situations: steering operation, braking, and driving on a relatively rough road surface with undulations. In addition, the suspension link extends in the longitudinal direction of the vehicle body, and between the two fluid-filled bushings provided at the front and rear ends of each fluid chamber, there are a fluid chamber that shrinks and deforms due to the action of force in the longitudinal direction of the vehicle body, and a fluid chamber that expands and deforms. Because there is a fluid passage that connects the fluid chambers with each other, if this fluid passage is not blocked, even if the fluid chamber is deformed due to force applied to the tire, etc. in the longitudinal direction of the vehicle body, the fluid chamber will change from contracting to expanding. Fluid flows to the front, ensuring greater compliance and improving riding comfort.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the control circuit, Fig. 2 is a sectional view of the fluid-filled bushing device in a free state where no external force is applied to the rod member, Fig. 3 is a drawing in a state where a tensile force is applied, and Fig. 4 is a sectional view of the fluid-filled bushing device. Diagram of compressive force acting state, 5th
The figure is a perspective view showing an example of a suspension type. In the figure, 21 is a switching valve, 25 and 26 are passages, and 3
1 and 41 are fluid-filled bushes; 32 and 42 are inner cylinders; 33 and 43 are outer cylinders; 34 and 44 are rubber walls;
5, 36, 45, and 46 are fluid chambers, 54 is a suspension link, 4 and 5 are processing circuits, and 7 is a logic circuit.

Claims (1)

[Claims] 1. A suspension link extending in the longitudinal direction of the vehicle body, and a fluid-filled bushing provided at the front and rear ends of the suspension link, and a spring constant of both fluid-filled bushings in the longitudinal direction of the vehicle body, This is a suspension control device for a vehicle that simultaneously controls fluid pressure in two or more levels, large and small, and includes a sensor that detects the steering operation state, a sensor that detects the brake state, and a sensor that detects the braking state of the vehicle body. A processing circuit that inputs the signal from the vertical vibration acceleration sensor and outputs a signal of acceleration near the sprung resonance frequency of the vehicle body, and a processing circuit that inputs these three types of signals and generates two or more levels of signals depending on the driving and road surface conditions. and a control circuit that receives signals from the control circuit to mutually connect a fluid chamber that shrinks and deforms and a fluid chamber that expands and deforms by the action of a force in the longitudinal direction of the vehicle body in each fluid chamber between the two fluid-filled bushes. and an actuator that automatically and simultaneously switches the spring constants of the two fluid-filled bushings so that the connecting fluid passages can be communicated and shut off, and when any of the three types of detection signals is detected, the actuator causes the two fluids to A suspension control device characterized in that the spring constant of the enclosed bushing is automatically variably controlled toward a larger value.