JPS6246365B2 - - 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 to 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 such as the low/medium vehicle speed range or the high load range, is set, and the system suspends the vehicle in advance when the driving state is within this range. In addition to setting the suspension characteristics of the transmission to be hard, when the vehicle speed is higher than a relatively high setting value, that is, when the transmission is shifted to 3rd or 4th gear, it is necessary to There is no room for acceleration, and on the other hand, if you make it hard, the ride quality will deteriorate during pitching or at high speeds, so the suspension characteristics are controlled to be soft. 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 when the vehicle speed is below a set value, the excess output of the engine is large based on the relationship between the vehicle speed and the engine load. The present invention is characterized in that it is configured to detect that the suspension system is in the operating range and output a drive signal to the adjustment means for hardening the suspension characteristics of the suspension device.

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, which are soft signals and hard signals, respectively, to the step motor 8 and the solenoid valve 11 in each suspension device 3, 3, 4, and 4. is configured to receive a vehicle speed signal C from a vehicle speed sensor 13 that detects the vehicle speed of the automobile, and a load signal D from a load sensor 14 that detects the engine load.

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 wheel.
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 side orifice 30b or the contraction side orifice 30d in the main valve 30, and in addition, through the orifice 37a of the orifice valve 39. The attenuation rate of the damper 6 is also switched to a communicated state, and the damping 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.
A relatively high set vehicle speed V ₁ (for _{example ,} 60 km/h) or less (shaded area X in Figure 6). When the operating state of the vehicle indicated by the vehicle speed signal C and the load signal D is in the region X, the step motor 8 and the solenoid valve 1 are
1, drive signals A and B that harden the dampers and springs of the suspension devices 3 and 4 are output.

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 reed switch that outputs a pulse signal with a frequency corresponding to the vehicle speed is used, and the load sensor 14 uses the accelerator opening to detect the engine load.
An accelerator switch is used that turns off when the opening is above a certain degree corresponding to P ₀ . The pulse signal C from the vehicle speed sensor 13 is input to the low speed comparator 62 via the frequency-voltage converter 61, and when the vehicle speed is below a very low constant vehicle speed _V0 , the pulse signal C is output from the comparator 62 to a high level. A low speed signal E of "H" is output, and when the accelerator switch 14 is OFF (engine load is above a constant load _P0 ), a high load signal F of high level "H" is output from the inverter 63.
These low speed signal E and high load signal F are input to the OR circuit 64. Further, the pulse signal C is passed through a frequency-voltage converter 61 to a high-speed comparator 65.
The set vehicle speed V ₁ is also input and the vehicle speed is relatively high.
At this time, the comparator 65 outputs a high-speed signal G of high level "H". This high speed signal G and the above
The output signal H of the OR circuit 64 is inputted to the AND circuit 66 after only the former is inverted.
The output signal I of the AND circuit 66 is outputted to the step motor 8 and the solenoid valve 11 as drive signals (hard signals) A and B via the drive circuit 53. Therefore, the drive signals A and B are output when either the low speed signal E or the high load signal F is at a high level "H" and the high speed signal G is at a low level "L". In other words, the operating state is in region X shown in FIG.

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

First, when the vehicle starts, the vehicle speed is less than a constant vehicle speed _V0 , 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 this and outputs drive signals (hard signals) A and B to the step motor 8 and the solenoid valve 11 via the drive circuit 53. Therefore, in the suspension devices 3 and 4 on 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. , a passage 3 that communicates the upper oil chamber 31 and the lower oil chamber 32 of the damper 6;
8a is shut off, and the solenoid valve 11 is closed, so that the air chamber 7 and the accumulator 10 forming a spring are closed.
is blocked. 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-mentioned control to harden the suspension characteristics of the suspension devices 3 and 4 is performed when the vehicle speed decreases to a constant vehicle speed V ₀ or less during the previous operation stop.
When the vehicle starts, the suspension characteristics are already in a hard state. Therefore, pitching of the vehicle body at the time of starting is reliably prevented.

Furthermore, even when the engine load is above the constant load P ₀ and the vehicle speed is below the relatively high set vehicle speed V ₁ during normal driving, the operating state is within the region X in FIG. 6, so the controller 12 outputs drive signals (hard signals) A and B to the step motor 8 and solenoid valve 11 based on signals C and D from the vehicle speed sensor 13 and load sensor 14. Therefore, in this case as well, the suspension characteristics of the suspension devices 3 and 4 are set to be hard, thereby preventing pitching of the vehicle body in the rearward direction 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 There is no.

Here, even if the engine load is greater than the constant load P ₀ , if the vehicle speed is higher than the relatively high set vehicle speed V ₁ , the transmission has already been shifted to 3rd or 4th gear and further rapid acceleration is performed. In order to improve the ride comfort when climbing hills or driving at high speeds, in this case, the drive signals A and B that harden the suspension characteristics are not output, or the drive signals that soften the suspension characteristics are output. The suspension devices 3 and 4 are then set to a soft state.

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 the region X' on the low-speed, high-load side of curve a is the region where control is performed to harden the suspension characteristics, but when the vehicle speed is relatively high and above the set vehicle speed V ₁ , sudden acceleration occurs. Since there is no room for this, the region where the vehicle speed is _V1 or higher is excluded from the region X', as in the embodiment described above.

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. As a result, the above problems are definitely resolved, and the suspension characteristics are not made unnecessarily hard when the vehicle speed is relatively high and there is no room for rapid acceleration. A soft ride comfort is ensured at times.

[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 the controller receives the output signals from the vehicle speed sensor and the load sensor, and detects that the surplus engine output is in an operating region where the engine has a large surplus output based on the relationship between the vehicle speed and the engine load when the vehicle speed is below a set value. and outputs a drive signal to the adjustment means for hardening the suspension characteristics of the suspension device.