JPH0479844B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a device for controlling the spring characteristics and damping characteristics of a suspension bushing in a shock absorber for a vehicle. (Prior Art) The suspension bushing described above is designed to improve the damping characteristics and/or Spring characteristics can be changed. However, after the shock absorber is supported on the vehicle body side, the damping characteristics of the bush are uniquely determined, and in order to change these characteristics, the elastic body must be replaced. The characteristics of the suspension bushing are usually set to suit the most frequently used driving conditions. Therefore, for example, when a passenger car is driven with all occupants on board, the spring constant of the suspension bush tends to be too small, resulting in unstable steering and poor ride comfort. (Object of the Invention) The object of the invention is to automatically change the characteristics of the suspension bushings to a state suitable for driving with a maximum number of passengers, thereby stabilizing steering performance and improving riding comfort. An object of the present invention is to provide a suspension bushing characteristic control device capable of controlling the characteristics of a suspension bush. (Structure of the Invention) Therefore, the characteristic control device for the shock absorber suspension bush of the present invention is structured as follows. That is, the elastic body has a hollow bag inside, and the characteristics of the elastic body are changed by supplying or discharging pressure fluid to the inside of the bag. The fluid pressure circuit of the hollow bag includes a supply of pressure fluid to the bag;
A pressure control valve is provided that can selectively switch between draining and closing the circuit. A control circuit for electrically controlling this pressure control valve is configured to maintain the pressure control valve in a pressure fluid supply state for a certain period of time when the vehicle is stopped and the vehicle is fully occupied, and then the fluid pressure circuit is turned on. Even when the bag is closed and the vehicle is started, a signal is issued to maintain the internal pressure of the hollow bag at an increased level. (Example) Examples of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2 showing suspension bushes (also called upper supports or strut mounts) of the shock absorber, a metal support member 14 is fixed to the vehicle body (not shown) by bolts 13. It is something that A metal connecting member 22 is connected to this support member 14 through an elastic body 23 such as rubber.
A ball bearing 28 that supports the upper end of a piston rod (none of which is shown) of the shock absorber is fixed to the shaft. The elastic body 23 described above is vulcanized and bonded to the supporting member 14 and the connecting member 22, respectively, and as is clear from FIG. A portion 25 is formed. Inside these hollow parts 25, a hollow bag body 3 made of a stretchable material such as rubber is provided.
6 is included. Further, each of these hollow bags 36 has a cap 38, and each cap 38 projects to the outside of the support member 14, and the hose 26 is connected thereto.
are connected. Pressure fluid such as oil is supplied to or discharged from each of the bags 36 through these hoses 26. By controlling the supply and discharge of the pressure fluid, the spring characteristics and damping characteristics of the elastic body 23 can be changed. Next, a fluid pressure circuit 50 that controls the supply and discharge of pressure fluid to each of the hollow bags 36 will be explained with reference to FIG. This fluid pressure circuit 50 includes a pump 51 that pumps pressure fluid (for example, oil), a reservoir tank 52, and a first solenoid valve 53 and a second solenoid valve 5.
The pressure control valve A is provided with a pressure control valve A having a Both electromagnetic valves 53 and 54 constituting this pressure control valve A are arranged in series in the fluid pressure circuit 50.
When the first electromagnetic valve 53 is not energized, the pressure fluid forms a return path from the hollow bag body 36 to the reservoir tank 52 as shown in the figure, and when energized, the pressure fluid forms an outgoing path from the pump 51 to the hollow bag body 36. It functions to configure. Further, the second solenoid valve 54 functions to close the fluid pressure circuit 50 in the illustrated non-energized state, and to open this circuit 50 when energized.
Therefore, depending on the combination of energization and de-energization of both electromagnetic valves 53 and 54, the pressure inside the hollow bag body 36 changes as shown in the following table.

[Table] Next, control circuit B controls the energization and de-energization of current to both electromagnetic valves 53 and 54 of the pressure control valve A.
This will be explained with reference to FIG. First, this circuit B has four input terminals 56 to 59, of which three input terminals 56 to 58 are connected to the pressure sensor 6.
0 to 62 are connected, and the remaining input terminal 59 is connected to a vehicle speed sensor 63. Each pressure sensor 60 to 62 may be connected to a seat (not shown), for example.
The sensors 60 to 62 are turned on and off depending on whether or not an occupant sits on the seat, and each sensor 60 to 62 is turned on when all the occupants (or a predetermined number of occupants) are in the vehicle. becomes. It should be noted that these pressure sensors 60 to 62 are essentially used to detect the load carried by the vehicle occupants, and therefore can be replaced with, for example, an internal pressure sensing sensor of a shock absorber. The vehicle speed sensor 63 is normally turned on and off at a frequency proportional to the rotation speed by a magnet provided on the output shaft of the vehicle. The speed determination circuit 64 is an F/V converter for converting the pulse train signal from the vehicle speed sensor 63 into a voltage.
Converter 65 and setting device 66 for setting the reference voltage
and the voltage value from the F/V converter 65 is set by the setting device 66.
and a comparator 67 that outputs a high signal when the voltage exceeds the voltage value from . The signal from this comparator 67 will be expressed as SA hereinafter. Note that the reference voltage of the setting device 66 is set to a voltage equivalent to when the vehicle is stopped. The pressure determination circuits 68 to 70 are mainly composed of transistors TR1 to TR3 that output high and low signals depending on whether each of the pressure sensors 60 to 62 is turned on or off. Signals from each of these determination circuits 68 to 70 are hereinafter expressed as SB to SD. The AND circuit 71 is for matching the signals SA to SD, and outputs a high signal when all of these signals SA to SD are input as high signals. The signal from the AND circuit 71 will hereinafter be expressed as SE. The electromagnetic valve drive circuit 74 includes monostable multi-hybrators 75 and 76 (hereinafter abbreviated as "monostable"),
It is composed of an exclusive OR circuit 77 (hereinafter referred to as "EXOR") and amplifiers 78 and 79. The monostable 75 outputs a high signal for a certain period of time in response to the rise of the output signal SE from the AND circuit 71. This output signal is expressed as SF. The other monostable 76 outputs a high signal in response to the fall of the signal SE, and this output signal is represented by SG. In addition, the above EXOR77 has each monostable 75,
It outputs the exclusive OR of the respective signals SF and SG from 76, and these output signals are
Represented by SH. The amplifiers 78 and 79 amplify the signals SF and SH, and the output signals SF' and
SH' drives the second solenoid valve 54 and the first solenoid valve 53, respectively. In the above configuration, when the vehicle is stopped and the vehicle is fully occupied, each of the pressure sensors 60 to 62 is turned on, and the high signals SB1 to SD1 shown in FIG. 5 are output from the respective pressure determination circuits 68 to 70. At the same time, the comparator 67 of the speed determining circuit 64 determines that the vehicle speed is zero and outputs a high signal _SA1 . These high signals SA ₁ ~
The AND circuit 71 inputting SD ₁ outputs the high signal SE ₁ shown in FIG. As a result, the monostable 75 outputs the signal SF ₁ , which passes through the amplifier 78 and becomes the output signal SF' ₁ to energize the second solenoid valve 54. Also, due to the signal SF ₁ from the monostable 75,
EXOR77 outputs signal SH ₁ , which is transmitted to amplifier 7
9 and becomes the output signal SH' ₁ to the first solenoid valve 53.
energize. By energizing both the electromagnetic valves 53 and 54, the internal pressure of the hollow bag body 36 increases, as is clear from the table above. Then, the output signal _SF1 from the monostable 75 becomes a low signal after a certain period of time as shown in FIG. 5, and each electromagnetic valve 53, 54 becomes de-energized again. As a result, the hollow bag body 36
The internal pressure remains elevated. After this, when the vehicle starts, the speed determination circuit 6
The high signal SA ₁ from 4 becomes a low signal, and accordingly, the signal SE ₁ from the AND circuit 71 also changes to a low signal. This causes a high signal from the monostable 76.
SG ₁ is output, and EXOR 77 outputs a high signal SH ₂ again. As a result, only the first electromagnetic valve 53 is energized by the signal SH' ₂ outputted through the amplifier 79. Therefore, as is clear from the above table, the internal pressure of the hollow bag 36 does not change. The high signal _SG1 of the monostable 76 becomes a low signal after a certain period of time, and even if the first electromagnetic valve 53 is closed, the internal pressure of the hollow bag body 36 remains elevated. In this way, when the vehicle is running with the maximum number of passengers on board, the internal pressure of the hollow bag body 36 is kept high and the spring constant of the elastic body 23 of the suspension bushing is increased, thereby improving steering stability and riding comfort. can be achieved. Although the case has been described in which there are four hollow bags 36, the number of the bags 36 can be increased or decreased freely, and it is also possible to replace the hollow bags 36 with one continuous bag, for example. It is also naturally possible to use a computer as the control circuit B. (Effects of the Invention) As described above, the present invention increases the internal pressure of the hollow bag body in the elastic body of the suspension bushing under the conditions that the vehicle is stopped and the vehicle is occupied at capacity, and then the vehicle When the vehicle is started, the internal pressure of the hollow bag remains high no matter how the running condition changes, and as long as the above conditions are met, the spring constant of the elastic body is kept high to maintain the vehicle. Driving stability can be improved, and its control is extremely simple.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view of a suspension bushing, FIG. 2 is a sectional view taken along the line -- in FIG. 1, FIG. 3 is a schematic diagram of a fluid pressure circuit, and FIG. 4 is a control circuit. FIG. 5 is a time chart showing the operating timing of the control circuit as it changes over time. 23...Elastic body, 36...Hollow bag body, 50...Fluid pressure circuit, A...Pressure control valve, B...Control circuit.

Claims (1)

[Claims] 1. A hollow bag is provided inside the elastic body, and the characteristics of the elastic body are changed by supplying or discharging pressure fluid to the inside of the bag. In the suspension bush of the shock absorber, the fluid pressure circuit of the hollow bag is provided with a pressure control valve that can selectively switch between supplying and discharging pressure fluid to the bag, or closing the circuit. The control circuit for controlling
When the vehicle is stopped and the vehicle is fully occupied, the pressure control valve is maintained in a pressure fluid supply state for a certain period of time, and then the fluid pressure circuit is closed to maintain the internal pressure of the hollow bag even when the vehicle is started. 1. A characteristic control device for a suspension bush of a shock absorber, characterized in that it is configured to issue a signal for holding the shock absorber in a raised position.