JPH0479842B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a characteristic control device for a suspension bush of a shock absorber. Generally, a shock absorber is supported by a vehicle body via a suspension bushing made of rubber or the like, but by changing the hardness or shape of this bushing, the height of the vehicle can be changed. However, in the past, there was no effective means to change the shape and hardness of the bushings depending on the driving conditions of the vehicle after they were mounted on the vehicle body. There was a problem in that it had to deal with the driving conditions of the vehicle. For this reason, this bushing tends to be adapted to the driving conditions in which it is most commonly used, so the vehicle height may not be optimal when the vehicle is running at high speeds, and the vehicle may be dissatisfied with the stability at high speeds. There were other problems. Therefore, in the present invention, the characteristics of the suspension bushing can be changed to automatically change the vehicle height to be suitable for high-speed driving without impairing the stability of the vehicle when the vehicle is running.
The object of the present invention is to provide a characteristic control device for a suspension bush of a shock absorber. In order to achieve the above object, the present invention discharges the fluid in the suspension bushing within a first predetermined time when the vehicle speed is equal to or higher than a predetermined value and the steering wheel is within a predetermined range. The present invention is characterized in that the vehicle height is automatically lowered by discharging the fuel, and furthermore, when the above conditions are no longer satisfied, the vehicle height can be raised within a second predetermined time period. Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. First, the structure of the suspension bush in this example will be explained. In FIG. 1, reference numeral 1 designates a support structure that supports the upper end of a shock absorber (not shown) via a support member 2 to a vehicle body (not shown). The support structure 1 consists of a connecting member 3, a suspension bush (hereinafter referred to as an elastic member) 4, and a pipe 5, and the connecting member 3 further includes a connecting part 6 that connects the upper end of a piston rod (not shown).
In the illustrated example, the connecting portion 6 is a ball bearing, and by attaching the upper end of a piston rod (not shown) to the inner race of the ball bearing with a bolt or the like, it supports a shock absorber (not shown). . Next, the elastic member 4 will be explained. In this example, it is made of rubber, and is vulcanized and bonded to the support member 2 and the connection member 3, respectively. In this example, the elastic member 4 has four hollow parts, and a hollow bag body 8 made of a stretchable material such as rubber is provided inside each hollow part. On the other hand, each hollow bag body 8 is connected to a pipe 5 from the outside via a cap 9. This piping 5 is connected to a fluid supply device 10 provided outside the system, which controls the supply and discharge of fluid (oil is used in this example) to the hollow bag body 8. It's summery. Next, the fluid supply device 10 will be explained.
This is a pump 1 for fluid conveyance as shown in Figure 3.
1, a reservoir 12, first and second solenoid valves 13,
14, and a control circuit 16. The first and second solenoid valves 13 and 14 are ordinary two-position switching valves, and the hollow bag body 8
The internal pressure changes as shown in Table 1. In addition, 13
A shows a blind stopper.

[Table] Next, the control circuit 16 will be explained. First, a vehicle speed sensor 17 and a steering switch 18 are connected to input terminals 16a and 16b of the control circuit 16. In this example, a normal reed switch is used as the vehicle speed sensor 17, and it is turned on and off at a frequency proportional to the rotation speed of the magnet provided on the output shaft of the engine (not shown). ing. Steering switch 1
8 is also a reed switch, which can be turned on or off by a magnet installed on the steering wheel of the vehicle (not shown).
It is becoming more and more common to turn it off. Therefore, as shown in FIG. 5, an ON signal is output when the steering wheel is in the neutral position, when the steering angle is small, or when the steering wheel is rotated 360 degrees to the left or right. Next, 19 is a speed determination circuit, which in this example includes an F/V converter 21 for converting a pulse train signal from the vehicle speed sensor 17 into a voltage, a setting device 22 for setting a reference voltage, and an F/V converter 21 for converting a pulse train signal from the vehicle speed sensor 17 into a voltage. A comparator 23 that outputs a Hi signal when the voltage value from the /V converter 21 becomes higher than the voltage value from the setting device 22.
(The signal from this comparator 23 will be expressed as SA hereinafter). 20 is a steering judgment circuit, which selects Hi and Lo depending on whether the steering switch 18 is turned on or off.
(The signal from the steering determination circuit 20 will be hereinafter referred to as SB). 24 is an AND circuit for matching the signal SA from the speed judgment circuit 19 and the signal SB from the steering judgment circuit 20;
It is more familiar than 4a. Furthermore, the output signal from now on
SC has a waveform as shown in FIG. 6 (that is, it becomes a signal in which the signals SA and SB match). Reference numeral 25 denotes a solenoid valve drive circuit, which in this example consists of monostable multivibrators 25a and 25b (hereinafter referred to as monostable), exclusive OR circuit 25c (hereinafter referred to as EXOR), and amplifiers 25d and 25e.
The monostable 25a is for outputting a Hi signal for a first predetermined period of time in response to the rise of the signal SC, and the output signal from then on becomes SD shown in FIG. Similarly, the monostable 25b outputs a Hi signal for a second predetermined period of time in response to the fall of the signal SC, resulting in the signal SE shown in FIG. Note that the first predetermined time and the second predetermined time may or may not be equal. EXOR25c is monostable 25a,
This is for calculating the exclusive OR of the respective signals SD and SE from 25b, and the resulting output signal is SG shown in FIG. 25d, 25e
are the signals SD and SG to drive the solenoid valves 13 and 14.
It is designed to amplify current, and is more similar to a normal current amplifier. Note that the future output signal SE′,
SG' has the same timing as the signals SD and SG shown in FIG. Next, the action and effect will be explained. For example, when driving at high speed on a highway, etc., if the vehicle speed exceeds 80 km/h, the speed determination circuit 19 will issue a Hi signal SA1 shown in FIG. ) is output. On the other hand, when the steering wheel is in a neutral state or the steering angle of the steering wheel is small during such high-speed driving (the steering wheel is not turned significantly during high-speed driving), the steering switch 18 is turned ON as shown in Fig. 5. Therefore, the steering judgment circuit 2
0, a Hi signal SB1 shown in FIG. 6 (FIG. 6 shows a state in which the handle is positioned at or near neutral at time t1) is output. Next, when Hi signals SA1 and SB1 are output,
The AND circuit 24 outputs the Hi signal SC1 shown in FIG.
is activated and outputs Hi signal SD1. Then,
The solenoid valve 14 is operated via the EXOR 25c and the amplifier 25e. Therefore, the pressure inside the hollow bag 8 decreases as shown in Table 1 by the operation of the electromagnetic valve 14, so that the elastic member 4 is compressed by the weight of the vehicle. This lowers the height of the vehicle, improving straight-line performance and stability when driving at high speeds. Note that the monostable 25a is automatically turned off after operating for the first predetermined period of time, and the operation of the solenoid valve 14 is canceled, so if the above-mentioned running condition remains,
The vehicle height remains low (solenoid valves 13 and 14
When both are not operating, the hollow bag body 8 is in a sealed state as shown in Table 1). Next, when the vehicle speed decreases from the above-mentioned state, the Hi signal SA1 from the speed determination circuit 19 becomes Lo, so the Hi signal SC1 from the AND circuit 24 becomes
becomes Lo (this corresponds to time t4 in Figure 6).
Then, the monostable 25b is activated by the falling portion of this Hi signal SC1 and outputs the Hi signal SE1, so that the solenoid valves 13 and 14 are activated, respectively, via the amplifier 25d, EXOR 25c, and amplifier 25e. For this reason, the hollow bag body 8 is
, the pressure inside the hollow bag body 8 increases and returns to its original state. In other words, the vehicle height becomes normal. Furthermore, the monostable 25b is automatically turned off after operating for the second predetermined period of time, and the operation of the solenoid valves 13 and 14 is canceled, so if the above-mentioned driving condition remains, the vehicle height will remain at the normal height. is maintained. In this example, a case has been described in which there are four hollow bags 8, but this number may be increased or decreased as appropriate. (For example, if the hollow bag body 8 is formed into a U-shape close to a circle, the number of hollow bags 8 can be reduced to one.) Furthermore, the control circuit 16
Alternatively, it can be constructed from a microcomputer. As described above in detail, according to the characteristic control device for the shock absorber suspension bush of the present invention, the control circuit controls the fluid pressure circuit so that the vehicle speed is equal to or higher than a predetermined value and the steering angle of the steering wheel is within a predetermined range. By switching the pressure control valve to the fluid discharge side for a first predetermined period of time when the condition that the hollow bag becomes inside is satisfied, the fluid inside the hollow bag inside the elastic body of the suspension bush of the shock absorber is discharged and the hollow bag is discharged. Reduces pressure in the body. Therefore, the elastic body is compressed by the weight of the vehicle, lowering the vehicle height, and improving straight-line performance and stability during high-speed driving. Furthermore, since the above-mentioned fluid discharge is limited to the first predetermined time period, the vehicle height is changed within the first predetermined time period, so that stability is improved by the vehicle height change operation during the control of the pressure control valve. not be damaged. Further, when the condition is no longer satisfied, the pressure solenoid valve is switched to the supply side for a second predetermined period of time to increase the pressure inside the hollow bag and return the vehicle height to its original state. At this time as well, since the above-mentioned fluid supply is limited to the second predetermined time period, the vehicle height is changed within the second predetermined time period, so the vehicle height is stabilized by the vehicle height change operation during the control of the pressure control valve. There is no loss of sexuality. Further, when the vehicle height is not changed as described above, since the fluid pressure circuit is closed, the vehicle height is not changed, so that the stability of the vehicle is not impaired. Moreover, since the aerodynamic characteristics are improved by lowering the vehicle height, it also has the secondary feature of improving fuel efficiency.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a side sectional view mainly showing the suspension bushing, and FIG.
The figure is a sectional view taken along the - line in Fig. 1, Fig. 3 is an explanatory diagram showing the fluid supply device, Fig. 4 is a circuit diagram mainly showing the control circuit, and Fig. 5 shows the switching characteristics of the steering switch with respect to the steering angle. The characteristic diagram, FIG. 6, is a timing chart showing temporal changes in each signal of the control circuit. 4...Elastic member (suspension bush), 8...Hollow bag body, 15...Pressure control valve, 16...Control circuit.

Claims (1)

[Claims] 1. A shock absorber suspension bushing having a hollow bag inside the elastic body and configured to change the characteristics of the elastic body by supplying or discharging pressure fluid to the inside of the bag;
A pressure control valve provided in the fluid pressure circuit of the hollow bag body and capable of selectively switching between supplying and discharging pressure fluid to the bag body or closing the fluid pressure circuit, and electrically controlling this pressure control valve. A characteristic control device for a shock absorber suspension bushing having a control circuit for controlling the characteristics of a suspension bush of a shock absorber, the control circuit controlling a condition that the vehicle speed is a predetermined value or more and the steering angle of the steering wheel is within a predetermined range. When the above conditions are satisfied, the pressure control valve is switched to the fluid discharge side for a first predetermined period of time, and when the above conditions are no longer satisfied, the pressure control valve is switched to the fluid supply side for a second predetermined period of time, and the other A characteristic control device for a shock absorber suspension bushing, characterized in that it has a function of closing the fluid pressure circuit at certain times.