JPH085299B2 - Suspension device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a vehicle suspension device including front and rear support rods that regulate movement of wheels in the vehicle front-rear direction.

[Prior art]

As a prior art of a suspension device provided with a tension rod which is a front and rear support rod, there is, for example, Japanese Patent Application No. 59-95956 previously filed by the applicant.

The suspension device is a suspension device including front and rear support rods, one end of which is connected to a vehicle body-side member and the other end of which is connected to a wheel-side member via rubber bushes to restrict movement of a wheel in the front-rear direction. At least one of the rubber pushes is provided with a pair of main liquid chambers arranged in the vehicle front-rear direction, and auxiliary liquid chambers are respectively connected to the respective main liquid chambers, and the main liquid chamber and the auxiliary liquid chambers forming the set are connected. A longitudinal acceleration detector for outputting a signal corresponding to the unsprung longitudinal acceleration on the wheel side, which is provided with buffer drive means capable of changing the volume of the auxiliary liquid chamber so as to keep the total volume constant, is connected via the longitudinal support rod. Is provided, and the buffer drive means is driven and controlled by the output from the longitudinal acceleration detector, whereby the main liquid chamber and the auxiliary liquid chamber can be controlled according to the vibration input to the front and rear support rods. By moving the liquid between and, the elastic push of the rubber push having both liquid chambers is facilitated and the spring constant in the front-back direction is softened, the vibration is effectively reduced and the interior of the vehicle such as drumming and road noise is reduced. I try to reduce the noise.

[Problems to be solved by the invention]

However, in such a prior art, a buffer drive means capable of changing the volume of the auxiliary liquid chamber so that the total volume of the main liquid chamber and the auxiliary liquid chamber forming a set is constant, for example, a cylinder device and a step motor. Since it is configured with a control circuit, the buffer drive means is driven and controlled according to the unsprung longitudinal acceleration on the wheel side detected by the longitudinal acceleration detector.
Not only was the entire apparatus large and expensive, but the control contents were also complicated, which was insufficient.

[Means for solving problems]

The present invention has been made by paying attention to such an insufficient point of the prior art, and the first invention is that one end is a vehicle body side member and the other end is a wheel side member via rubber push. In a suspension device including front and rear support rods that are connected together to regulate the movement of the wheels in the front and rear direction, at least one of the rubber bushes has a liquid chamber arranged in one of the vehicle front and rear directions with respect to the support center. And a flow rate control means capable of controlling the flow rate of the working fluid supplied from the fluid pressure source to the fluid chamber while connecting the fluid chamber to the fluid pressure source.
An unsprung longitudinal acceleration detector that outputs a signal corresponding to the unsprung longitudinal acceleration on the wheel side connected through the longitudinal support rod is provided, and the flow rate control means is driven by the output from the unsprung longitudinal acceleration detector. By controlling, it aims at solving the above-mentioned inadequate points.

A second aspect of the invention is a suspension device including front and rear support rods, one end of which is connected to a vehicle body-side member and the other end of which is connected to a wheel-side member via rubber bushes to restrict movement of the wheels in the front-rear direction. In at least one of the rubber pushes, a liquid chamber arranged in one of the vehicle front-rear direction with respect to the support center thereof is provided, and the liquid chamber is connected to the hydraulic pressure source via an electromagnetic switching valve and fixed. An unsprung longitudinal acceleration detector that outputs a signal corresponding to the unsprung longitudinal acceleration on the wheel side, which is connected to the tank through the throttle and is connected through the longitudinal support rod, is provided. It is an object of the present invention to solve the above-mentioned inadequate points by controlling the drive of the electromagnetic switching valve by the output of the above.

[Action]

Thus, in the first invention, the liquid chamber is arranged in one of the vehicle front-rear directions in at least one of the rubber bushes provided at both ends of the front-rear support rod interposed between the vehicle body side member and the wheel side member. Flow rate control means for controlling the flow rate of the hydraulic fluid from the hydraulic pressure source supplied to the fluid chamber is driven and controlled by the output from the longitudinal acceleration detector for detecting the unsprung longitudinal acceleration of the vehicle. By generating hydraulic pressure in the chamber according to the magnitude of unsprung longitudinal acceleration, the rubber bush having the liquid chamber is positively elastically deformed to effectively absorb the vibration transmitted through the front and rear support rods. can do.

According to a second aspect of the invention, the flow rate of the hydraulic fluid supplied from the hydraulic pressure source is controlled by an electromagnetic switching valve to supply the hydraulic fluid to the fluid chamber, and the electromagnetic switching valve is driven and controlled by the output from the longitudinal acceleration detector. Since the hydraulic pressure of the hydraulic pressure source is directly supplied to the input side of the switching valve, it becomes possible to immediately supply the hydraulic fluid of a predetermined pressure to the liquid chamber by switching the electromagnetic switching, and the vibration input to the front and rear support rods is increased. Even when is a high frequency vibration, the responsiveness to the input vibration can be enhanced.

〔Example〕

 Hereinafter, the present invention will be described based on illustrated embodiments.

1 and 2 are views showing an embodiment of the present invention.

First, the structure will be described. Reference numeral 1 shown in FIG. 1 is a tension rod showing a specific example of the front and rear support rods, and a rod body 2 and rubber bushes 3 (fixed at both axial ends of the rod body 2). The configuration of the rubber bush at the other end is the same as that of the conventional one, so that the illustration is omitted.). In the tension rod 1, for example, a rubber bush 3 shown in the drawing is connected to a vehicle body side member such as a tension rod bracket, and a rubber bush not shown is connected to a wheel side member such as a transverse link. Is arranged so that the axis of the is oriented in the vehicle front-rear direction X (left-right direction in the figure).

The rubber bush 3 includes an outer cylinder 4 to which one end of the rod body 2 is fixed on the outer side, an inner cylinder 5 concentrically arranged on the inner side of the outer cylinder 4, and a rubber shape interposed between the both cylinders 4 and 5. It is composed of an elastic body 6, and the two cylinders 4, 5 and the rubber-like elastic body 6 are fixed to each other by vulcanization adhesion or the like. Then, the rubber-like elastic body 6
A slit 7 located on the front side of the vehicle and a space 8 located on the rear side of the vehicle are formed on both sides of the inner cylinder 5 which is the support center of the rubber bush 3 in the vehicle front-rear direction X.

While the slit 7 is open to the atmosphere, the void 8
Is liquid-tightly defined inside the rubber-like elastic body 6, and is provided in the outer cylinder 4 in the space 9 defined inside the cylinder shaft portion 2a provided at the end of the rod body 2. They communicate with each other through the opening 4a. Two voids 8 and 9 communicated through this opening 4.
Constitutes a liquid chamber 10 and is filled with hydraulic fluid such as oil. The liquid chamber 10 is connected to a hydraulic pressure source 13 via a supply pipeline 12 connected to a pipe 11 provided on the cylindrical shaft portion 2a.

The hydraulic pressure source 13 has a hydraulic pump 14, a flow control valve 15 connected to the discharge side of the liquid chamber pump 14, and a relief valve 16 connected to the outlet side of the flow control valve 15, Hydraulic pump
The suction port of 14, the pilot side outlet of the flow control valve 15, and the outlet of the relief valve 16 are all connected to a reservoir tank 17. A return conduit 19 having an opening / closing valve 18 showing one specific example of the flow rate control means is connected to the supply conduit 12 that connects the hydraulic pressure source 13 and the liquid chamber 10 and one end of which is a reservoir. Returning to tank 17.

The opening / closing valve 18 is a 2-port / 2-position electromagnetic switching valve by a spring offset / electromagnetic method. In a normal state, the passage is connected by the urging force of the spring 18a, and when an exciting current is supplied to the electromagnetic solenoid 18b. ,
The exciting force switches the position of the valve to close the passage. The drive control of the opening / closing valve 18 is performed by a control signal output from a control circuit 20 described later, for example, a logical value "1".
Alternatively, it is driven to open and close by a signal of logical value "0".

As shown in FIG. 2, the control circuit 20 has a bandpass filter 21, an A / D converter 22, a comparator 23, and a drive circuit 24. The control circuit 20 is provided outside. A longitudinal acceleration detector 30 is connected. From the longitudinal acceleration signal Dα input from the longitudinal acceleration detector 30, the bandpass filter 21 communicates only the frequency component of 20 to 40 Hz, which causes harshness, for example, in the vehicle interior noise.

The harshness component communicating through the bandpass filter 21, after being converted into a digital signal by the A / D converter 22, the comparator 23, a predetermined value which is a reference preset as vibration and noise that can be sensed by a person as harshness. Compared to. Then, when the magnitude of the harshness component is larger than a predetermined value, a signal is output from the comparator 23 to the drive circuit 24. As a result, the drive circuit 24 outputs the drive current I to the electromagnetic solenoid 18b, which causes the open / close valve 18
Operates to close the return line 19.

The longitudinal acceleration detector 30 is attached to, for example, a wheel-side member that is an unsprung member, and outputs a frequency signal according to the magnitude of unsprung longitudinal acceleration to the control circuit 20.
Therefore, the unsprung longitudinal acceleration signal Dα will be described as positive or negative by the frequency equal to the vibration transmitted through the tension rod 1.

 Next, the action acts.

Now, assuming that the vehicle is traveling straight on a flat road,
Since the vibration input to the tension rod 1 via the wheel and the wheel side member is small, there is a gap between the outer cylinder 4 fixed to the rod body 2 and the inner cylinder 5 pivotally supported by the vehicle body side member. No relative displacement occurs. In addition, normally, when the vehicle is traveling straight on a flat road, its unsprung longitudinal acceleration is zero or a value close to it, so that it is output from the longitudinal acceleration detector 30 which detects this unsprung longitudinal acceleration. The value of the longitudinal acceleration signal Dα is also zero or a value close thereto.

Therefore, since the control circuit 20 does not output the drive current as the control signal, the electromagnetic solenoid 18 of the on-off valve 18 is
b keeps the original demagnetized state, opens the road, and returns all the hydraulic fluid supplied from the hydraulic pressure source 13 to the reservoir tank 17 via the return conduit 19. Therefore, since the hydraulic fluid discharged from the hydraulic pump 14 is not supplied to the liquid chamber 10, the hydraulic fluid is relatively displaced between the outer cylinder 4 and the inner cylinder 5 arranged so as to sandwich the liquid chamber 10. Does not act to cause

In this way, when traveling on a flat road where the input vibration from the road surface is small, the vibration of 20 to 40 Hz that causes harshness is not input to the vehicle body via the tension rod 1,
The tension rod 1 is not caused to expand or contract in the axial direction, and maintains the initial state to regulate the movement of the wheels in the vehicle longitudinal direction.

From this state, when the vehicle travels on uneven road and the vibration from the road surface is input to the tension rod 1 via the wheel and the wheel-side member, the tension rod 1 is in the vehicle front-rear direction X due to the vibration frequency. It vibrates in the axial direction of the rod body 2. Thereby, the outer cylinder 4 of the rubber bush 3
Vibrates integrally with the rod body 2 and reciprocates in the same direction. On the other hand, since the inner cylinder 5 of the rubber bush 3 is axially supported by the vehicle body side member and does not move, a relative displacement in the vehicle front-rear direction X occurs between the two cylinders 4 and 5.

On the other hand, at the same time when the vibration is input, the longitudinal acceleration detector 30
Detects the unsprung longitudinal acceleration of the vehicle and sends a signal Dα corresponding to the longitudinal acceleration to the control circuit 20. The control circuit 20 receiving the longitudinal acceleration signal Dα takes out only the set frequency component of 20 to 40 Hz that causes harshness in the vehicle out of the input vibration, and after converting it into a digital signal by the A / D converter 22, The comparator 23 compares it with a predetermined value, and when the longitudinal acceleration detected value is larger than the predetermined value, the drive current I which is a control signal is passed through the drive circuit 24 to the electromagnetic solenoid 18
Output to b.

As a result, the electromagnetic solenoid 18b is excited to switch the open / close valve 18 to the operating position, so that the return conduit 19 is closed. As a result, the hydraulic fluid discharged from the hydraulic pump 14 is introduced into the liquid chamber 10, and the rubber-like elastic body 6 is forced to separate the rod body 2 from the inner cylinder 5 by the pressure of the hydraulic fluid. Elastically deforms.

In this case, the switching timing of the open / close valve 18 is determined based on the input vibration when the rod main body 2 is, for example, X _{R in} FIG.
It is set so that the electromagnetic solenoid 18b is excited and the return conduit 19 is closed when pulled in the direction (rear of the vehicle). Then, the outer cylinder 4 and the rod body 2 are displaced in the same direction as the load transmitted to the rod body 2.

As a result, the input vibration transmitted to the rod body 2 is absorbed by the forced elastic deformation that acts on the rubber bush 3, and thus the input vibration is prevented from being transmitted to the vehicle body. Therefore, the vibration transmitted to the vehicle body via the tension rod 1 is reduced, and thus the vehicle body vibration and the vehicle interior noise can be effectively suppressed. Moreover, according to the present invention, the opening / closing valve 18 connected to the hydraulic pressure source 13 is
Since it has a simple structure of opening and closing, it does not require expensive devices such as cylinder devices and step motors used in the prior art, so not only can the entire device be manufactured at low cost, but also the control response The control contents can be made simple and the control contents can be made simple.

In the above embodiment, a part of the control circuit 20 is 20 to 40 Hz.
Although the example of reducing the harshness using the bandpass filter 21 that passes only the frequency component of is described, the bandpass filter can be set to any value as necessary, for example, the passband is set to 30 to 60 Hz. As a result, the drumming of the vehicle interior noise and the road noise of the vehicle interior noise can be effectively suppressed by setting the pass band to 80 to 100 Hz.

 FIG. 3 shows another embodiment of the present invention.

In this embodiment, the liquid chamber 10 and the hydraulic pressure source 13 in the previous embodiment are used.
An opening / closing valve 18A is provided between the opening and the closing valve, and a throttle 25 is provided on the downstream side of the opening / closing valve 18A, so that the opening / closing valve 18A directly controls the hydraulic pressure of the liquid chamber 10. for that reason,
In this embodiment, a 2-port / 2-position spring-offset / electromagnetic electromagnetic switching valve whose passage is closed in a normal state is used as the opening / closing valve 18A, and a line pressure of a predetermined pressure is constantly provided on the upstream side of the opening / closing valve 18A. It is configured to give. The other structure is the same as that of the above embodiment.

Thus, in this embodiment, since the line pressure of the supply pipe line 12 is always set to the predetermined pressure, the line pressure of the predetermined pressure can be applied to the liquid chamber 10 substantially at the same time as the operation of the opening / closing valve 18A. Therefore, even when the vibration input to the rod body 2 is a high frequency vibration, the responsiveness to the input vibration can be further enhanced.

Although the liquid chamber 10 is provided on the rod body 2 side of the tension rod 1 in the above embodiment, the liquid chamber may be provided on the side opposite to the rod body 2 side. It is needless to say that the rubber bush 3 having the liquid chamber may be provided at the same time, and both rubber bushes may be simultaneously configured to perform the same control as described above.

〔The invention's effect〕

As described above, according to the first aspect of the invention, the liquid chamber is provided in the vehicle front-rear direction in at least one of the rubber bushes provided at both ends of the front-rear support rod interposed between the vehicle body-side member and the wheel-side member. And a flow rate control means for controlling the flow rate of the hydraulic fluid from the hydraulic pressure source supplied to the fluid chamber, the flow rate control means is provided before and after detecting the unsprung longitudinal acceleration of the vehicle. The drive is controlled by the output from the acceleration detector to generate a hydraulic pressure in the liquid chamber according to the magnitude of the unsprung longitudinal acceleration. for that reason,
The vibration transmitted to the front and rear support rods can be absorbed by elastically deforming the rubber bush having the liquid chamber. Therefore, the vibration transmitted to the vehicle body through the front and rear support rods can be absorbed, so that the vehicle body vibration and the vehicle interior noise due to the input vibration can be effectively reduced. Moreover, since the flow control means, which is an opening / closing valve, and the hydraulic pressure source have a simple structure, the vibration transmitted to the front and rear support rods can be absorbed by the on / off operation of the flow control means. Not only can it be manufactured at low cost, but the response of control can be improved.

Further, according to the second invention, in addition to the effect of the first invention, the flow rate of the working fluid supplied from the hydraulic pressure source is controlled by the electromagnetic switching valve to be supplied to the liquid chamber, and the electromagnetic switching valve is operated. By controlling the drive from the output from the longitudinal acceleration detector, the hydraulic pressure of the hydraulic pressure source is directly supplied to the input side of the electromagnetic switching valve. It is possible to supply the power, and even when the vibration input to the front and rear support rods is high frequency vibration, it is possible to obtain an effect that the responsiveness to the input vibration can be enhanced.

[Brief description of drawings]

1 is an explanatory view showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a control circuit according to the present invention, and FIG.
The figure is an explanatory view showing another embodiment of the present invention. 1 ... Tension rod (front and rear support rod), 2 ... Rod body, 3 ... Rubber bush, 4 ... Outer cylinder, 5 ... Inner cylinder, 6 ... Rubber-like elastic body, 10 ... Liquid chamber, 12 ...... Supply line, 13 ...... hydraulic pressure source, 18,18A ...... Open / close valve (flow rate control means), 18b ...... Electromagnetic solenoid, 19 ...... Return line, 20 ...
… Control circuit, 25 …… Aperture, 30 …… Longitudinal acceleration detector, X
...... Vehicle longitudinal direction

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yosuke Akatsu, 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) Reference JP-A-59-34908 (JP, A) JP-A-59-53223 (JP, A) JP-A-60-215410 (JP, A) JP-A-60-240509 (JP, A) Jitsuko 63-32723 (JP, Y2)

Claims (2)

[Claims] 1. A suspension device including front and rear support rods, one end of which is connected to a vehicle body side member and the other end of which is connected to a wheel side member via rubber bushes, for restricting movement of a wheel in the front-rear direction. At least one of the rubber bushes is provided with a fluid chamber arranged in one of the vehicle front-rear directions with respect to its support center, and this fluid chamber is connected to the fluid pressure source, and at the same time, the fluid pressure source is supplied to the fluid chamber. An unsprung longitudinal acceleration detector that outputs a signal corresponding to the unsprung longitudinal acceleration on the wheel side, which is connected through the longitudinal support rod, is provided with a flow rate control means that can control the flow rate of the liquid. A suspension device characterized in that the flow rate control means is driven and controlled by an output from a detector. 2. A suspension device comprising front and rear support rods, one end of which is connected to a vehicle body side member and the other end of which is connected to a wheel side member via rubber bushes, for restricting movement of a wheel in the front-rear direction. At least one of the rubber bushes is provided with a liquid chamber arranged in one of the vehicle front-rear directions with respect to its support center, and this liquid chamber is connected to the hydraulic pressure source via an electromagnetic directional switching valve, and a fixed throttle is provided. An unsprung longitudinal acceleration detector that outputs a signal corresponding to the unsprung longitudinal acceleration on the wheel side connected to the tank via the longitudinal support rod is provided, and the output from the unsprung longitudinal acceleration detector is provided. A suspension device, characterized in that the electromagnetic directional control valve is driven and controlled by means of an electromagnetic switch.