JPH0147322B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suspension mechanism for a vehicle that can reliably prevent nose dive when the brakes of a vehicle are applied.

Generally, vehicles are equipped with suspension devices such as shock absorbers, air springs, air levelers, struts, etc. in order to improve riding comfort. Therefore, when the brakes are applied while the vehicle is running, a nose dive occurs in which the vehicle body leans forward due to the load shift. This nose dive becomes larger as the damping force characteristics of the suspension system become smaller, and an extremely large nose dive occurs during sudden braking. If this nose dive is large, it not only worsens the riding comfort, but also
In severe cases, there was a risk of injury to the crew.

Such nose dive increases in proportion to the magnitude of vehicle deceleration. Therefore, a method has been proposed in which this deceleration is detected and the damping force characteristics of the suspension system are changed according to the magnitude of the deceleration. However, this method has the disadvantage that the response time required to change the damping force characteristics of the suspension system after deceleration is detected is long, and a sufficient nose dive prevention effect cannot be obtained.

The present invention has been made in view of the above points, and the present invention detects changes in the hydraulic pressure of the master cylinder and operates an adjustment device that makes the damping force characteristics of the suspension system variable. is good,
It is an object of the present invention to provide a suspension mechanism for a vehicle that can effectively deal with nose dive.

To achieve the above object, the present invention provides a suspension system for suspending a vehicle body, an adjusting device for changing the damping force characteristics of the suspension system, and a brake fluid pressure change in a hydraulic brake system for applying brakes to the vehicle. a pressure detector that detects and outputs a pressure signal, and a control device that operates the adjustment device based on the pressure signal output from the pressure detector, the control device configured to detect the pressure signal output from the pressure sensor. a pressure change rate calculating means for calculating a pressure change rate by differentiating the pressure signal of the brake fluid, and when the pressure change rate calculated by the pressure change rate calculating means exceeds a preset value, the suspension and actuating means for actuating the adjusting device to increase the damping force characteristics of the device.

With this configuration, the pressure change rate calculation means calculates the pressure change rate by differentiating the rising portion of the pressure signal output from the pressure detector, and the actuation means calculates the pressure change rate so that the pressure change rate reaches a predetermined set value. Since the damping force characteristics can be increased by immediately operating the adjustment device when the brake fluid exceeds the limit, the suspension system can be operated in response to changes in brake fluid pressure before the nose dive begins, thereby suppressing the occurrence of the nose dive.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, in FIG. 1, reference numeral 1 denotes the suspension part of an automobile as a vehicle, and the suspension part 1 is provided with left and right front wheels 2, 2 and rear wheels 3, 3, respectively. In the vicinity of 2, there are struts 4,
5, shock absorbers 6, 7 (generally coil springs (not shown) are installed in parallel) are installed near the rear wheels 3, 3, respectively, and the struts 4, 5 and the shock absorbers 6, 7 A vehicle body (not shown) is suspended on top of the vehicle to form a suspension system for the vehicle. 8 is a brake pedal, and 9 is a master cylinder that supplies oil through hydraulic piping to brake equipment (not shown) such as a brake cylinder when the brake pedal 8 is depressed. A hydraulic brake system is constructed with hydraulic piping that connects the When the brake pedal 8 is depressed to operate the brake, the hydraulic pressure within the master cylinder 9 increases.
12 is a pressure transducer installed in the master cylinder 9;
The pressure transducer 12 detects an increase in the hydraulic pressure within the master cylinder 9, and converts this change in hydraulic pressure into an analog voltage signal or current signal (hereinafter referred to as a pressure signal).
When the rate of change of these signals exceeds a certain value, the control device 10 operates the adjustment device 11 attached to the struts 4, 5 and the shock absorbers 6, 7 to 4, 5. Increase the damping force characteristics of the shock absorbers 6, 7.

FIG. 2 shows a circuit diagram of the control device 10. The hydraulic pressure in the master cylinder 9 is detected by a pressure transducer 12,
The control device 10 changes the pressure signal proportional to the hydraulic pressure.
A differentiation circuit 13 provided inside calculates the rate of change. The rate of pressure change determined by the differentiating circuit 13 is output as a pulse, and when the peak value of the pulse exceeds a certain reference value, the monostable multivibrator 14 is activated to output a voltage with a predetermined pulse width. This output voltage is applied to the output circuit 15 to operate each regulating device 11 for a certain period of time.

FIG. 3 shows the shock absorber 4 to which the adjustment device 11 is attached, 16 is an outer cylinder of the shock absorber 4, 17 is an inner cylinder accommodated in the outer cylinder 16, and the inner cylinder 17 is arranged vertically. inner lid body 18,1
9, and the outer cylinder 16 is closed by an upper lid 20 and a lower lid 21, respectively. Said inner cylinder 1
A piston 22 is slidably provided within 7,
The inner cylinder 17 is divided into two chambers A and B. Further, a chamber C is formed between the outer cylinder 16 and the inner cylinder 17. Thus, chambers A and B serve as oil chambers filled with oil, and chamber C serves as an oil reservoir chamber in which air is stored above. A piston rod 23 is fixed to the piston 22, and the piston rod 23 penetrates the inner cover body 18 and the upper cover 20 and protrudes to the outside, and has a mounting portion 2 provided at its tip.
4 is attached to the sprung portion of the vehicle, and a mounting portion 25 provided on the lower cover 21 is attached to the unsprung portion of the vehicle.
26 is a suction valve that allows oil to flow only from oil chamber B to oil chamber A provided in piston 22; 27 is a suction valve that allows oil to flow only from oil sump chamber C to oil chamber B provided in inner lid 19; When the piston 22 descends, the suction valve 26 opens and the oil in the oil chamber B flows into the oil chamber A. When the piston 22 ascends, the suction valve 27 opens and flows into the oil sump chamber. Oil fluid flows into oil chamber B from C. Therefore, based on the flow of the oil, the piston 2
A damping force for 2 is given. For this purpose, the inner lid body 18 is provided with an oil passage 28 communicating with the oil chamber A, and the other side of the oil passage 28 is connected to an oil passage pipe 29 that is vertically disposed on the inner lid body 18. It's open. A damping force generating valve 32 is provided in the middle of the oil passage pipe 29, which is biased against a valve seat 31 by a spring 30 and generates a damping force by drilling an orifice therein. Further, the lower end portion of the oil passage pipe 29 is closed by a spring seat 33. Thus, the oil that has been damped by passing through the damping force generating valve 32 is
The oil flows out through an oil hole 34 provided between the valve seat 31 and the spring seat 33.

The adjusting device 11 is interposed between the oil hole 34 and the oil reservoir chamber C, and the adjusting device 11 includes a plunger 36 housed in the casing 35 and a plunger 36 that protrudes onto the casing 35 to drive the plunger 36. It is generally composed of a solenoid 37 provided therein. The plunger 36 is normally urged upward by a spring 38, and when the solenoid 37 is energized by a signal from the output circuit of the control device 10, the spring 38
8 and displaces the plunger 36 downward.
Reference numeral 39 denotes an oil hole bored in the casing 35, and the oil hole 39 is always in communication with the oil hole 34. 40 again
41 is an oil passage bored in the plunger 36, and 41 is a communication passage bored in the casing 35 so as to keep the oil passage 40 and the chamber C in constant communication. Therefore, when the solenoid 37 is in a de-energized state, the oil chamber A is
is communicated with the oil reservoir chamber C, and when the solenoid 37 is energized, the plunger 36 is lowered, thereby cutting off communication between the oil hole 39 and the oil passage 40, and the oil in the oil chamber A is blocked. become a state.

On the other hand, the struts 4 and 5 are also constructed such that suspension springs are attached to the shock absorbers 6 and 7 shown in FIG. 3, and the wheels 2 are attached to knuckle pins, so illustration and description of these will be omitted.

The vehicle suspension mechanism according to the present invention has the above configuration, and its operation will be explained with reference to FIG. 4. When the brake 8 of the vehicle is depressed, oil fluid is supplied from the master cylinder 9 to the brake equipment. At this time, the pressure inside the master cylinder 9 increases, so the pressure change is reflected in the pressure transducer 1.
2 as a pressure signal.

Now suppose that the brakes are suddenly applied to the vehicle. At this time, the pressure of the brake fluid in the master cylinder 9 rises rapidly as shown in FIG. 2a.
This pressure change is detected by a pressure transducer 12, and the pressure signal is input to a differentiation circuit 13 to calculate the rate of change. The differentiating circuit 13 calculates the rising portion of the pressure signal and outputs it as a pulse as shown in FIG. 4b. When the rise of this pulse exceeds a certain reference value, the monostable multivibrator 14 is activated and outputs a one-shot pulse for a predetermined time t as shown in FIG. 3c. While the monostable multivibrator 14 is operating, the output circuit 15 energizes the solenoid 37 of each adjustment device 11, and the plunger 36 is displaced downward against the spring 38. Therefore, communication between the oil chamber A and the oil reservoir chamber C of each strut 4, 5 and the shock absorbers 6, 7 is cut off, and the oil chamber A
The oil inside is locked. Therefore, their damping force characteristics become significantly larger. As the damping force characteristics of the struts 4 and 5 increase, the front part of the vehicle is prevented from descending, and the damping force characteristics of the shock absorbers 6 and 7 increase, preventing the rear part of the vehicle from floating up. and nose dive is suppressed.

In this way, the adjusting device 11 is connected to the master cylinder 9.
Because it operates immediately in response to changes in brake fluid pressure, its response speed is extremely fast, ensuring that struts 4 and 5 are activated before the nose dive begins.
and the shock absorbers 6, 7 can be operated.

On the other hand, if the brake 8 is depressed gently, no nose dive occurs. In this case, the brake fluid pressure changes smoothly. Therefore, the output signal of the differentiating circuit 13 does not take a large peak value as shown in FIG. 4b. Therefore, the trigger voltage, which is the reference for the operation of the monostable multivibrator 14, is set to a signal value that has the rate of change in pressure of the brake fluid that occurs when the brake is applied suddenly enough to cause a nose dive, and the differential The monostable multivibrator 14 may be activated when the signal from the circuit 13 exceeds the trigger voltage. Then, when the brake 8 is gently depressed, the adjustment device 11
does not operate, and the damping force characteristics of the struts 4, 5 and shock absorbers 6, 7 are maintained at a small state, and their original function of damping is performed without impairing the ride comfort of the vehicle.

Furthermore, since the monostable multivibrator 14 operates only for a certain period of time t, the brake 8
When the possibility of a nose dive disappears, such as when the solenoid 37 of the adjustment device 11 is cut off and the plunger 36
is restored, and the oil chamber A and the oil reservoir chamber C are communicated again via the damping force generating valve 32, so that the damping force characteristics of the struts 4, 5 and the shock absorbers 6, 7 become smaller. It has the original function as a suspension device.

In the above embodiment, the adjusting device 12 was shown as being attached to suspension devices such as the struts 4, 5 and the shock absorbers 6, 7, but instead of or together with these, other suspension devices such as air springs, air springs, etc. An adjustment device 12 may be attached to the levelizer or the like, and the output of the control device 11 may be applied to the adjustment device 12. In addition, as a means for increasing the damping force characteristics of the struts 4, 5 and the shock absorbers 6, 7, the oil hole 39 is
Although it has been described that the communication between the oil chamber A and the oil passage 40 is blocked, the above-mentioned damping force can also be reduced by restricting the flow passage from the oil chamber A to the oil reservoir chamber C by displacement of the plunger 36 without completely blocking the communication. properties can be increased. Furthermore, although the pressure detector 12 has been described as being provided in the master cylinder 9, it may also be provided in the middle of the hydraulic piping leading to the brake equipment. In this case, it is preferable to provide it near the master cylinder 9 in consideration of the line resistance of the hydraulic piping. Furthermore, if a trigger signal is input again while the monostable multivibrator 14 is in operation, for example when the brake 8 is depressed twice, the monostable multivibrator 14 will be locked in response to the second signal. can be configured so that they do not operate redundantly.

As described in detail above, in the vehicle suspension system of the present invention, the adjustment device is configured to increase the damping force characteristics of the suspension system based on the rate of change in pressure of the brake fluid in the hydraulic brake system including the master cylinder. Since the brake equipment is configured to operate when the vehicle is suddenly braked, it is possible to increase the damping force characteristics of the suspension system immediately before the vehicle nose dives, making it effective. nose dive can be suppressed.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of a vehicle suspension mechanism according to the present invention, Fig. 2 is a circuit diagram showing the suspension mechanism, and Fig. 3 is a shock absorber when the suspension system used in the present invention is used as a shock absorber. Fig. 4a is a pressure signal diagram of a pressure transducer, Fig. 4b is an output diagram of a differential circuit, and Fig. 4c is an output diagram of a monostable multivibrator. show. DESCRIPTION OF SYMBOLS 1... Suspension part of an automobile, 4, 5... Strut, 6, 7... Shock absorber, 9... Master cylinder, 10... Control device, 11... Adjustment device.

Claims (1)

[Scope of Claims] 1. A suspension system that suspends a vehicle body, an adjustment device that changes the damping force characteristics of the suspension system, and a pressure change that detects changes in the pressure of brake fluid in a hydraulic brake system that brakes the vehicle. A pressure detector that outputs a signal; and a control device that operates the adjustment device based on the pressure signal output from the pressure sensor, and the control device controls the amount of brake fluid output from the pressure sensor. a pressure change rate calculation means for calculating a pressure change rate by differentiating a pressure signal; and a damping force characteristic of the suspension device when the pressure change rate calculated by the pressure change rate calculation means exceeds a preset value. and actuating means for actuating the adjusting device to increase the amount of the adjustment device. 2. The vehicle suspension according to claim 1, wherein the actuating means is configured to actuate the adjusting device so as to increase the damping force for a predetermined period of time from when the rate of pressure change exceeds a preset value. mechanism.