JPS6246364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile suspension, and more particularly to a suspension in which suspension characteristics are variably controlled according to driving conditions.

It is already known that the spring constant of a spring and the damping rate of a damper, that is, the suspension characteristics of a suspension of an automobile, can be changed depending on the driving condition. For example, according to Japanese Utility Model Application Publication No. 55-109008, in a car equipped with shock absorbers on the front and rear wheels, at high speeds the damping force of the shock absorber on the rear wheel side is lowered relative to the front wheel side. A ``vehicle suspension'' characterized by an understeer characteristic, and a neutral steer characteristic or oversteer characteristic at low speeds as a damping force relationship that is opposite to that at high speeds.
Ideas related to this have been disclosed. This is intended to simultaneously provide straight-line stability at high speeds and turning maneuverability at low speeds.

However, in order to generally improve the drivability and ride comfort of a vehicle, it is not sufficient to simply change the suspension characteristics depending on the vehicle speed as in the above-mentioned invention. For example, when starting or suddenly accelerating, the vehicle body pitches backwards due to the acceleration acting on the center of gravity of the vehicle body, but such pitching of the vehicle body can be prevented by appropriately controlling the suspension characteristics. Alternatively, it is important to reduce the amount of noise in order to improve the riding comfort during starting and the like.

The present invention focuses on the above points, and in a suspension system in which the suspension characteristics are variably controlled according to the driving condition, the pitching of the vehicle body is prevented or reduced by making the suspension characteristics hard when starting or suddenly accelerating. The purpose of this is to prevent the pitching from causing discomfort to the occupants and improve riding comfort. In particular, in the present invention,
The driving range of the vehicle where starting and rapid acceleration is performed, in other words, the range where the surplus output of the engine is large is set, and the suspension characteristics of the suspension are set in advance to be hard when the driving condition is within this range. . This prevents deterioration of riding comfort by unnecessarily hardening the suspension characteristics in areas where starting or sudden acceleration is not performed, and prevents delays in suspension control during starting or sudden acceleration.

That is, the present invention provides a suspension device with variable suspension characteristics, an adjustment device that changes the suspension characteristics of the suspension device, a controller that operates the adjustment device, and a vehicle speed sensor that detects vehicle speed.
A load sensor that detects the load on the engine is provided, and the controller receives output signals from the vehicle speed sensor and the load sensor, and detects that the engine is in an operating range where the surplus output is large based on the relationship between the vehicle speed and the engine load. It is characterized in that it is configured to output a drive signal for hardening the suspension characteristics of the suspension device to the adjustment means when detected.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

As shown in FIG. 1, front wheels 1, 1 and rear wheels 2,
2 is a suspension device 3 that suspends the vehicle body;
3, 4, and 4 are provided respectively. Each of these suspension devices 3, 3, 4, and 4 is composed of a coil spring 5, a damper 6, and an air chamber 7, but the damper 6 has a structure that will be described later, and the damping rate can be switched in two stages. A step motor 8 is provided as an actuator for switching. Further, the air chamber 7 is connected to the accumulator 10 via a pipe 9, and a solenoid valve 11 is installed between the air chamber 7 and the accumulator 10 to disconnect communication between the two. A controller 12 is provided which outputs drive signals A and B to the step motor 8 and the solenoid valve 11 in each suspension device 3, 3, 4, 4, respectively. Vehicle speed signal C from vehicle speed sensor 13 that detects
and a load signal D from a load sensor 14 that detects the load on the engine are input.

Here, the specific structure of the suspension device will be explained.

As shown in FIG. 2, the suspension devices 3 and 4, whose upper ends are fixed to the vehicle body via a mounting member 21 and an elastic body 22, include an upper case 23 that forms the air chamber 7, and an upper case 23 that forms the air chamber 7. The lower end of the upper case 23 and the upper end of the lower case 24 are connected by a rolling diaphragm 25. is seal member 2
It is divided by 6. The lower case 24 is
Furthermore, it is composed of an outer cylinder 27 and an inner cylinder 28, and a piston rod 29 is inserted into the inner cylinder 28 so as to be able to slide vertically relative to the piston rod. The inside of the inner cylinder 28 is partitioned into an upper oil chamber 31 and a lower oil chamber 32. Further, a bottom valve 33 is provided at the lower end of the inner cylinder 28, and a space between the inner cylinder 28 and the outer cylinder 27 is a reservoir chamber 34. Here, the outer cylinder 27 has a mounting bracket 27 for a support mechanism that rotatably supports the vehicle.
A is provided. In addition, the above main valve 3
0, there is a check valve 30 as shown enlarged in FIG.
The extension side orifice 30b allows hydraulic oil to pass only from the upper oil chamber 31 to the lower oil chamber 32 side by the check valve 30c, and the lower oil chamber 3
A contraction-side orifice 30d that allows hydraulic oil to pass only from 2 to the upper oil chamber 31 side is provided. These constitute a damper 6 that quickly damps vibrations between the upper case 23 and the lower case 24, that is, the vehicle body side and the wheel side.

The piston rod 29 of the damper 6 is hollow, and a control rod 35 is rotatably inserted into the piston rod 29. This rod 35 is rotated by the step motor 8 through a rotation key 36 engaged at its upper end, and is connected to a valve body 37 provided at the lower end of the control rod 35 and a piston rod 29. An orifice valve 39 is constituted by a valve case 38 provided at the lower end. That is, as shown in FIG. 4, the upper oil chamber 3 formed in the cylindrical valve case 38
1 and the lower oil chamber 32,
The communication is interrupted by rotation of the valve body 37 fitted in the case 38, or communicated by an orifice 37a provided in the valve body 37. As a result, the upper oil chamber 31 and the lower oil chamber 32 are communicated only through the extension orifice 30b or the contraction orifice 30d of the main valve 30, and in addition, through the orifice 37a of the orifice valve 39. The attenuation rate of the damper 6 is switched to two levels, ie, a hard state and a soft state.

In addition, as shown in FIG. 2, the upper case 23
and the lower case 24 are provided with spring receivers 40 and 41, respectively, and the coil spring 5 is installed between these, and the coil spring 5 and the air in the air chamber 7 are connected to the springs of the suspension devices 3 and 4. It consists of In that case, the air chamber 7 is connected to the accumulator 1 via the pipe 9 and the solenoid valve 11 as described above.
0, the amount of air that acts as a spring is increased or decreased depending on whether the solenoid valve 11 is closed or opened, and thereby the spring constant of the spring is divided into two levels, large and small. state and soft state.

On the other hand, as shown in FIG. 5, the controller 12 includes input circuits 51 and 52 into which the vehicle speed signal C and the load signal D from the vehicle speed sensor 13 and the load sensor 14 are input, respectively, and the suspension device 3,
a drive circuit 53 that outputs drive signals A and B to the step motor 8 and the solenoid valve 11 in 4, respectively;
It is comprised of an arithmetic circuit 54 that operates the drive circuit 53 according to the vehicle speed and engine load indicated by the vehicle speed signal C and load signal D. The calculation circuit 54 also operates in a driving range where the excess output of the engine is large, which is determined by the relationship between the vehicle speed and the engine load, as shown in FIG.
An area (hatched area X in FIG. 6) is set, which is a combination of an area where the engine load is below V ₀ and a high load area where the engine load is above a constant load P ₀ . Then, the vehicle speed signal C
and the driving state of the vehicle indicated by the load signal D is in the area
, drive signals A and B for hardening the dampers and springs of the suspension devices 3 and 4 are outputted from the arithmetic circuit 54 to the step motor 8 and the solenoid valve 11 via the drive circuit 53. .

Here, a specific example of the configuration of the controller 12 will be explained with reference to FIG. In this example, a reed switch that outputs a pulse signal with a frequency corresponding to the vehicle speed is used as the vehicle speed sensor 13, and a load sensor 14 that measures the engine load by accelerator opening.
An accelerator switch is used that turns off at a certain opening corresponding to P ₀ or more. The pulse signal C from the vehicle speed sensor 13 is input to the comparator 62 via the frequency-voltage converter 61, and when the vehicle speed is below a constant vehicle speed _V0 , the comparator 6 outputs a high-level "H" low-speed signal. E is output, and the accelerator switch 14 is turned off (engine load is constant P ₀
(above), the inverter 63 outputs a high-level "H" high-load signal F. These low speed signals E
and high load signal F are input to the OR circuit 64, and when either one is at high level "H", the drive circuit 5
Drive signals A and B are outputted via 3.

Next, the operation of the above embodiment will be explained.

First, when the vehicle starts, the vehicle speed is below the constant vehicle speed V ₀ , so in the controller 12 to which the vehicle speed signal C is input from the vehicle speed sensor 13, the arithmetic circuit 54 determines whether the driving state is in the region X in FIG. It detects that the step motor 8 and the solenoid valve 11 have the drive signal A,
Output B. Therefore, in the suspension devices 3 and 4 for the front and rear wheels, the valve body 37 of the orifice valve 39 constituting the damper 6 is rotated by a certain angle from the state shown in FIG. 4 by the step motor 8. The passage 38a that communicates the upper oil chamber 31 and the lower oil chamber 32 of the damper 6 is shut off, and the electromagnetic valve 11 is closed, so that the air chamber 7 and the accumulator 10 forming the spring are shut off. As a result, both the dampers and springs of the suspension devices 3 and 4 are in a hard state, and therefore, even if a large acceleration is applied to the center of gravity of the vehicle body when the vehicle starts, pitching of the vehicle body in the rearward downward direction is prevented. That will happen. Here, the above control that hardens the suspension characteristics of the suspension devices 3 and 4 is performed so that the vehicle speed remains constant at the time of the previous stop.
This is done when V drops below ₀ , so the suspension characteristics are already in a hard state by the time the vehicle starts moving. Therefore, pitching of the vehicle body at the time of starting is reliably prevented.

Also, during normal driving, if the engine load is greater than the constant load P ₀ , that is, if the engine output is large and there is a possibility of sudden acceleration, the operating condition is within the region X in Fig. 6. , the controller 12 outputs drive signals A and B to the step motor 8 and the solenoid valve 11 based on the load signal D from the load sensor 14. Therefore, in this case as well, the suspension characteristics of the suspension devices 3 and 4 are set to be hard, and pitching in the downward direction of the vehicle speed is prevented when sudden acceleration is performed. In this case as well, since control is performed to harden the suspension characteristics when the driving condition enters the above region X, there may be a delay in switching the suspension characteristics to hard when sudden acceleration is actually performed. do not have.

In addition, in the non-shaded area of FIG. 6, that is, in the area Y where the vehicle speed is above the constant vehicle speed V ₀ and the engine load is below the constant load P ₀ , the controller 12 provides suspension to the step motor 8 and the solenoid valve 11. A signal is output that softens the characteristics. In that case,
The suspensions 3 and 4 on the front and rear wheels may be variably controlled to be hard or soft, respectively, in response to other driving conditions.

Next, other embodiments of the present invention shown in FIGS. 8 to 10 will be described.

In this embodiment, controller 12'
A-D to which the vehicle speed signal C and load signal D from the vehicle speed sensor 13 and load sensor 14 are respectively input.
A drive circuit 5 that outputs drive signals A and B to the converters 51' and 52', the step motor 8 and the solenoid valve 11.
3', an arithmetic circuit 54' that operates the drive circuit 53' when the driving state of the vehicle indicated by the vehicle speed signal C and the drive signal D is in a certain range, and a memory connected to the arithmetic circuit 54'. It consists of a device 55'. A map showing the relationship between vehicle speed and engine load as shown in FIG. 9 is set in the memory device 55'. This map shows that region X' on the low speed, high load side of curve a is the region where starting or rapid acceleration is performed.

In this embodiment, the controller 12' includes:
It operates according to the flowchart shown in FIG. That is, the actual vehicle speed and engine load are read from the vehicle speed signal C and the load signal D (step
S ₁ , S ₂ ), the point corresponding to the read value is the 9th point.
It is determined whether it is included in region X' in the map shown in the figure (step _S3 ). If the suspension falls within the region X', drive signals A and B are outputted to the step motors 8 and solenoid valves 11 in the suspension devices 3 and 4 so as to harden the suspension characteristics (step _S4 ). ). As a result, in this embodiment as well, pitching of the vehicle body at the time of starting and sudden acceleration is prevented or reduced, as in the previous embodiment.

In the above embodiments, the suspension characteristics are controlled for both the damper and the spring, but the suspension characteristics of only one of them may be variably controlled depending on the driving range. Also,
The engine load is determined by the amount of accelerator pedal depression,
It can be detected by throttle valve opening, intake pipe negative pressure, etc.

As described above, according to the present invention, the suspension characteristics of the suspension are made hard when the vehicle starts or suddenly accelerates, thereby preventing or reducing pitching in the rearward direction of the vehicle body. This results in
This solves the problem of the vehicle body pitching backwards when starting, etc., causing discomfort to the occupants, and improves the ride comfort of the vehicle. In particular, the present invention has a configuration in which a driving range in which starting and sudden acceleration is performed is set, and the suspension characteristics are hardened in advance when the driving state is within the range, so that delays in control of the suspension characteristics are prevented. Thus, the above problem is definitely solved.

[Brief explanation of the drawing]

1 to 7 show a first embodiment of the present invention, in which FIG. 1 is a control system diagram, FIG. 2 is a vertical cross-sectional view showing the specific configuration of the suspension device, and FIG. 3 is its essential parts. 4 is a cross-sectional view, FIG. 5 is a block diagram showing the configuration of the controller, FIG. 6 is a graph showing the operating area of the controller, and FIG. 7 is a specific circuit example of the controller. FIG. Figures 8 to 10 are the second embodiment of the present invention.
8 is a block diagram showing the configuration of the controller, FIG. 9 is a map of operating characteristics stored in the controller, and FIG. 10 is a flowchart showing the operation of the controller. . 3, 4... Suspension device, 8, 11... Adjustment means (8... Step motor, 11... Solenoid valve), 1
2, 12'...controller, 13...vehicle speed sensor,
14...Load sensor.

Claims (1)

[Claims] 1. A suspension device with variable suspension characteristics, an adjusting means for changing the suspension characteristics of the suspension device, a vehicle speed sensor for detecting vehicle speed, a load sensor for detecting engine load, and a controller for operating the adjusting means. and when the controller receives the output signals from the vehicle speed sensor and the load sensor and detects that the excess output of the engine is in a large operating range based on the relationship between the vehicle speed and the engine load, the controller controls the adjustment means. An automobile suspension characterized in that it is configured to output a drive signal for hardening the suspension characteristics of a suspension device.