JPH0450206B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a caster angle control device for a vehicle. Generally, the shock absorber is supported by the upper support of the vehicle body via a suspension push such as rubber, but by changing the attachment center of the shock absorber to this upper support, the caster angle of the wheel can be changed. . However, in the past, there was no effective means to change the caster angle by moving the mounting center depending on the driving conditions of the vehicle after installing the shock absorber on the vehicle body. This created the problem of having to deal with all driving conditions. For this reason, this caster angle tends to be adapted to the most frequently used driving conditions, and this has led to problems such as dissatisfaction with straight-line performance when the vehicle is running at high speeds. Therefore, an object of the present invention is to provide a caster angle control device that can automatically change the caster angle when the vehicle speed increases. In order to achieve the above goal, in the present invention, when the vehicle speed increases, the suspension pusher is deformed to move the mounting position of the shock absorber relative to the upper support, thereby changing the caster angle. It is characterized by: Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. First, the structure of the suspension pusher in this example will be explained. In FIG. 1, reference numeral 1 indicates a support structure that supports the upper end of a shock absorber (not shown) via an upper support 2 to a vehicle body (not shown). The support structure 1 consists of a connecting member 3, a suspension push (hereinafter referred to as an elastic member) 4, and a pipe 5, and the connecting member 3 further comprises 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 upper support 2 and the connecting member 3, respectively. In this example, the elastic member 4 has two hollow parts 7A and 7B, and inside these are hollow bags 8A and 8B formed of a stretchable material such as rubber.
is provided. On the other hand, piping 5 from the outside is connected to each of the hollow bags 8A, 8B via a cap 9.
This piping 5 is connected to a fluid supply device 10 provided outside the system.
The hollow bag body 8A,
The supply and discharge of fluid (oil is used in this example) to 8B is controlled. In this example, the hollow bag 8A is located at the front of the vehicle, and the hollow bag 8B is located at the rear of the vehicle. Next, the fluid supply device 10 will be explained.
This is a pump 1 for fluid conveyance as shown in Figure 3.
1, reservoir 12, and first and third solenoid valves 13
A, 13B and second and fourth solenoid valves 14A, 14B
It consists of a pressure control valve 15 and a control circuit 16. 1st to 4th solenoid valves 13A, 13B,
14A and 14B are ordinary two-position switching valves, and the pressure inside the hollow bags 8A and 8B changes as shown in Table 1 depending on the combination of energization and de-energization of these valves. In this example, the hollow bag body 8A is connected to the second solenoid valve 14A side, and the hollow bag body 8B is connected to the fourth solenoid valve 14B side. M indicates 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 is turned on and 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 setter 22 for setting a reference voltage, and so on. A comparator 23 that outputs a Hi signal when the voltage value from the F/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). Reference numeral 20 is a steering judgment circuit, which selects Hi or Lo depending on whether the steering switch 18 is turned on or off.
(The signal from the steering determination circuit ₂₀ will be referred to as SB hereinafter). 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). 25 is a solenoid valve drive circuit, which in this example includes monostable multivibrators 25a and 25b (hereinafter referred to as monostable) and exclusive logic circuit 25c (hereinafter referred to as EXOR).
and amplifiers 25d and 25e. The monostable 25a is for outputting a Hi signal for a predetermined period of time in response to the rise of the signal SC, and the output signal from now on becomes SD shown in FIG. Similarly,
The monostable 25b becomes Hi due to the falling of the signal SC.
It outputs a signal, which is the signal SE shown in FIG. The EXOR 25c is for taking the exclusive OR of the respective signals SD and SE from the monostables 25a and 25b, and the resulting output signal is SG shown in FIG. 25d, 25e are for driving the solenoid valves 13A, 13B, 14A, 14B,
It is used to amplify the signals SD and SG, and is more similar to a normal current amplifier. Note that the output signals SD' and SG' from now on will have 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 outputs a Hi signal SA ₁ shown in FIG. h) is output. On the other hand, when the steering wheel is in a neutral state or the steering angle is small while driving at high speeds (the steering wheel is not turned significantly when driving at high speeds),
As shown in FIG. 5, the steering switch 18
Since it is turned on, the steering determination circuit 20 outputs the Hi signal SB ₁ shown in FIG. Next, when the Hi signals SA ₁ and SB ₂ are output,
Since the AND circuit 24 outputs the Hi signal SC ₁ shown in FIG. 6 by ANDing these signals, the monostable 25a is activated by the rising portion of this Hi signal SC ₁ and outputs the Hi signal SD ₁ . . Then, the solenoid valves 13A and 13B are operated via the amplifier 25d, and the solenoid valves 14A and 14B are operated via the EXOR 25c and the amplifier 25e. For this reason,
As shown in Table 1, by the operation of the solenoid valves 13A, 13B, 14A, and 14B, the pressure in the hollow bag 8A increases and the pressure in the hollow bag 8B decreases, so that the upper end of the shock absorber (not shown) The connecting portion 6 supporting the upper support 2 moves rearward (to the right in the figure) with respect to the upper support 2. For this reason, the caster angle of the wheels becomes large, so that straight-line performance at high speeds is further improved. In addition, the monostable 25a is automatically turned off after operating for a predetermined time, and the solenoid valves 13A, 13B, 14
Since both of the solenoid valves A and 14B are deactivated, the caster angle remains large as long as the above-mentioned running condition remains. (The hollow bag body 8 is in a sealed state). Next, when the vehicle speed decreases from the above-mentioned state, the Hi signal SA ₁ from the vehicle speed determination circuit 19 becomes Lo, so the Hi signal SC ₁ from the AND circuit 24 becomes Lo.
(This corresponds to time t4 in FIG. 6). Then, the falling portion of this Hi signal SC ₁ activates the monostable 25b and outputs the Hi signal SE ₁ , so that the solenoid valves 14A and 14B are activated via the EXOR 25c and the amplifier 25e. Therefore, the pressure inside the hollow bag 8A decreases, and the pressure inside the hollow bag 8b increases, returning to the original state. In other words, it becomes a normal caster angle. It should be noted that the monostable 25b is automatically turned off after operating for a predetermined period of time, and the electromagnetic valves 14A and 14B are deactivated, so that the normal caster angle is maintained as long as the above-mentioned running condition remains. In this example, a case has been described in which there are two hollow bags 8A and 8B, but this number may be increased or decreased as appropriate. Further, the control circuit 16 in this example can also be configured by a microcomputer. Furthermore, it goes without saying that this example can be applied to any of the front wheels, rear wheels, and all wheels. That is, according to the configuration described in the claims of the present invention, when the vehicle speed is above a predetermined value and the steering angle of the steering wheel is small, the suspension pusher is automatically formed to increase the caster angle of the wheel. Therefore, it has the excellent feature of further improving straight-line performance when driving at high speeds.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a side sectional view mainly showing the suspension pushbutton, and FIG.
The figure is a sectional view taken along the - line in Figure 1, Figure 3 is an explanatory diagram showing the fluid supply device, Figure 4 is a circuit diagram mainly showing the control circuit, and Figure 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 pusher), 8... Hollow bag body, 15... Pressure control valve, 16... Control circuit.

Claims (1)

[Claims] 1. A shock absorber having at least two hollow bags inside an elastic body and configured to change the characteristics of the elastic body by supplying or discharging pressure fluid to the inside of the bags. A suspension pusher, a pressure control valve provided in the fluid pressure circuit of the hollow bag and capable of selectively switching between supplying and discharging pressure fluid to the bag or closing the circuit; A control device for controlling a caster angle in a vehicle has a control circuit for controlling the caster angle, and the control circuit is configured to control the caster angle when the vehicle speed is a predetermined value or more and the steering angle of the steering wheel is within a predetermined range. A caster angle control device for a vehicle, characterized by having a function of switching a pressure control valve so as to supply fluid to one of the hollow bags and discharge fluid from the other.