JPS6240204B2 - - 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.
A related idea has been disclosed. This is intended to simultaneously provide straight-line stability at high speeds and maneuverability at low speeds.

However, as mentioned above, when switching the suspension characteristics of the front and rear wheels to hard or soft depending on the driving condition, an abnormality in the control system may cause the front wheels to be soft and the rear wheels to be hard, especially at high speeds. When this happens, the car will be in an extremely dangerous situation. In other words, the steering characteristics tend to oversteer strongly, and the straight-line stability against disturbances such as crosswinds is significantly reduced, making the vehicle body more likely to sway, or dangerous phenomena such as the vehicle body turning more than expected when steering. arise.

The present invention has focused on the above points, and has developed a suspension system in which the suspension characteristics are variably controlled depending on the driving condition.Even if some abnormality occurs in the control system, the front wheels are soft and the rear wheels are hard. The purpose is to prevent this from occurring and ensure the driving stability of the vehicle.

That is, the present invention provides a suspension comprising suspension means for suspending a vehicle body on front wheels and rear wheels, adjustment means for changing the suspension characteristics of the suspension means, and a controller for operating the adjustment means, wherein the controller is , when detecting a condition in which the suspension characteristics of the front wheels are soft and the suspension characteristics of the rear wheels are hard, either the hard signal that hardens both the front and rear wheels or the soft signal that softens both the front and rear wheels is activated as described above. It is characterized in that it is configured to output to the adjustment means. According to such a configuration,
Even in the event of an abnormality in the control system, this prevents the front wheels from becoming soft and the rear wheels from becoming hard, thereby preventing the deterioration of vehicle driving stability and associated dangers due to this relationship in suspension characteristics. This will be prevented.

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 has suspension 3, 3, which suspends the car body.
4 and 4 are provided respectively. These suspensions 3, 3, 4, and 4 are all equipped with coil springs 5.
It consists of a damper 6, and an air chamber 7. The damper 6 has a structure that will be described later, so that the damping rate can be switched between two stages, and the front wheel suspension is used as the actuator to switch the damper 6. 3 is provided with a step motor 8, and the suspension 4 on the rear wheel side is provided with a step motor 9. The air chamber 7 is connected to the accumulator 11 via a pipe 10, and between the air chamber 7 and the accumulator 11, a solenoid valve 12 is provided for the suspension 3 on the front wheel side, and a solenoid valve 12 is provided for the suspension 3 on the rear wheel side. Similarly, a solenoid valve 13 is installed at each of the valves 4 and 4.

Then, a drive signal A is sent to the step motor 8 in the front wheel suspension 3, a drive signal B is sent to the solenoid valve 12, and a drive signal C is sent to the step motor 9 in the rear wheel suspension 4. Similarly, a controller 14 is provided which outputs a drive signal D to each of the electromagnetic valves 13, and the controller 14 receives a vehicle speed signal E from a vehicle speed sensor 15 that detects the vehicle speed of the automobile.
An application signal F from the application sensor 16 that detects the application of the vehicle, a brake signal G from the brake sensor 17 that detects the operation of the brake, and a start signal H from the start sensor 18 that detects the start of the vehicle.
Furthermore, the manual operation signal I from the manual switch 19
is configured so that it is input.

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

As shown in FIG. 2, the suspensions 3 and 4, whose upper ends are fixed to the vehicle body via a mounting member 21 and an elastic body 22, are connected to an upper case 23 forming the air chamber 7 and to the case 23. The lower end of the upper case 23 and the upper end of the lower case 24 are connected by a rolling diaphragm 25. A sealing member 26 is provided to partition the space. The lower case 24 is
Furthermore, it is composed of an outer cylinder 27 and an inner cylinder 28.
A piston rod 29 is inserted into the inner cylinder 28 so as to be relatively slidable up and down. Oil chamber 3
It is divided into 2. In addition, a bottom valve 33 is provided at the lower end of the inner cylinder 28, and
The space between the inner cylinder 28 and the outer cylinder 27 is a reservoir chamber 34. Here, the 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 the upper case 23 to the upper oil chamber 31 side is provided.
4, that is, a damper 6 is configured to damp vibrations between the vehicle body side and the wheel side.

The piston rod 29 in the damper 6 is hollow, and a control rod 35 is rotatably inserted into the piston rod 29. This rod 35 is configured to be rotated by the step motors 8 and 9 via a rotation key 36 engaged at its upper end, and is also configured to be rotated by the step motors 8 and 9 through a rotation key 36 engaged at its upper end. Valve case 3 provided at the lower end of the valve body 37 and piston rod 29
8 constitute an orifice valve 39. That is, as shown in FIG. 4, the cylindrical valve case 3
A passage 38a that communicates between the upper oil chamber 31 and the lower oil chamber 32 formed in the case 38 is blocked by rotation of the valve body 37 fitted in the case 38, or by an orifice 37a in the valve body 37. It is communicated. As a result, the upper oil chamber 31 and the lower oil chamber 32 are in communication with each other only through the extension side orifice 30b or the contraction side orifice 30d in the main valve 30, and the orifice 30b or 30d as well as the orifice The orifice 37a in the valve 39 is also switched to the communicating state, and the damping rate of the damper 6 constituted by these is switched to two levels, ie, hard and soft.

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 suspensions 3 and 4. It consists of In that case, since the air chamber 7 is connected to the accumulator 11 via the pipe 10 and the solenoid valves 12 and 13 as described above, the solenoid valves 12 and 1
3 is closed and opened, the amount of operating air as a spring is increased or decreased, and the spring constant is switched to two levels, large and small. As a result, the springs of the suspensions 3 and 4 are switched between hard and soft.

As shown in FIG. 2, the lower end of the lower case 24 is provided with a mounting bracket 42 for a support mechanism that rotatably supports the wheels.

On the other hand, the controller 14 is constructed as shown in FIG. That is, the vehicle speed sensor 1
5. Signals E~ from the turning sensor 16, brake sensor 17, starting sensor 18, and manual switch 19
Drive signals A, B (soft signals A ₁ ,
B ₁ or hard signals A ₂ , B ₂ ), and the drive signals C and D (soft signals C ₁ ,D ₁ or hard signal
C ₂ , D ₂ ), a rear wheel side changeover switch 53 that outputs
A relay 54 that closes in response to the energization signal J from the control logic section 51 and energizes both the changeover switches 52 and 53, and current detection installed on the energization circuits 52a and 53a to the changeover switches 52 and 53, respectively. It is composed of circuits 55 and 56. and,
The control logic unit 51 selects the changeover switches 5 for the front and rear wheels so that the suspension characteristics correspond to the operating conditions of the vehicle or the switch operations indicated by the signals E to I from the sensors and switches 15 to 19.
Switching signals K and L are outputted to the switching switches 2 and 53, and drive signals A to D, which are soft signals or hard signals, are outputted from the switching switches 52 and 53 in response. Further, the current detection circuits 55 and 56 detect the current flowing to the front wheel side and rear wheel side changeover switches 52 and 53, and feed back the detected results to the control logic section 51 as detection signals M and N.

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

Assuming that the car is currently running at a low to medium speed below a certain vehicle speed, and no actions such as turning or braking are being performed, and the manual switch 19 is not being operated, each sensor indicating this state The controller 14 receives signals E through I from the switches 15 through 19, and sends drive signals A through D to the step motors 8 and 9 and the solenoid valves 12 and 13 in the front and rear wheel suspensions 3 and 4. It outputs soft signals A ₁ to D ₁ as follows. Therefore, in the suspensions 3 and 4, the orifice valve 39 constituting the damper 6 is connected to the passage 3 as shown in FIG.
8a are in communication with each other through the orifice 37a, the damper 6 has a small damping rate, and the solenoid valves 12 and 13 are open, so that the air chamber 7 and the accumulator 11 are in communication with each other. Due to the communication, the spring constant of the air spring constituted by these is kept small. That is, in this case, the suspension characteristics of the front wheel suspension 3 and the rear wheel suspension 4 are both set to a soft state, and good riding comfort is obtained.

Further, when the vehicle speed enters a high speed range equal to or higher than the above-mentioned constant vehicle speed, in the controller 14, a switching signal K is output from the control logic section 51 to the front wheel side switching switch 52 based on the signal E from the vehicle speed sensor 15. , the relay 54 is closed by the energization signal J, and the changeover switch 52 is energized. Therefore, the drive signals A and B output from the changeover switch 52 are switched to hard signals A ₂ and B ₂ , and the step motor 8 of the front wheel suspension 3 is accordingly switched to the hard signals A 2 and B 2 .
is rotated by a certain angle, the orifice valve 39 in the damper 6 is shut off, and the solenoid valve 12 is closed to shut off the air chamber 7 and the accumulator 11, so that both the damper and the spring of the front wheel suspension 3 are hardened. The state will be as follows. As a result, the steering characteristics become understeer characteristics, and straight-line stability at high speeds is improved. Furthermore, when turning or braking, both the front wheel side and rear wheel side changeover switches 52, 53 in the controller 14 control the step motors 8, 9 of the front wheel side and rear wheel suspensions 3, 4 and the solenoid valve 12, Hard signals A ₂ to D ₂ are output to each of the suspensions 13, and the suspension characteristics of both suspensions 3 and 4 are set to hard, thereby reducing rolling and pitching of the vehicle body during turning or braking.

However, when an abnormality occurs in which the suspension characteristics of the front wheels become soft and the suspension characteristics of the rear wheels become hard during variable control of the suspension characteristics as described above, the controller 14 operates as follows.

For example, as shown in FIG. 6a, the control logic unit 51 switches the suspension characteristics of both the front and rear wheel suspensions 3 and 4 from soft to hard.
When switching signals K and L are output from the front wheel side and rear wheel side changeover switches 52 and 53, and an energization signal J is outputted to energize these switches 52 and 53, on the rear wheel side, Predetermined hard signals C ₂ and D ₂ were output from the changeover switch 53, and the step motor 9 and solenoid valve 13 of the suspension 4 operated normally, whereas on the front wheel side, the hard signal A from the changeover switch 52 was output. ₂ or
It is assumed that there is an abnormality in B ₂ or that these signals A ₂ and B ₂ are normal but that there is an abnormality in the step motor 8 or the solenoid valve 12 and that these do not operate normally. In this case, the rear wheel suspension 4 is switched to hard, while the front wheel suspension 3 is kept soft. At this time, the power supply to the rear wheel side changeover switch 53 is stopped when the changeover operation to the hard mode is completed, but the power supply to the front wheel side changeover switch 52 is not completed because the changeover operation to the hard mode is not completed. will continue indefinitely. This abnormality is detected by the current detection circuit 55 installed on the energizing circuit 52a of the changeover switch 52, and fed back to the control logic section 51 as a detection signal M.

When the control logic unit 51 receives the abnormality detection signal M, it sends a soft signal A ₁ to the front wheel side and rear wheel side changeover switches 52 and 53, as shown in FIG.
The switching signals K and L are outputted so as to output _D1 , and the energization signal J is again outputted to operate these changeover switches 52 and 53. As a result, soft signals A ₁ to D ₁ are output from both changeover switches 52 and 53 to the step motors 8 and 9 and solenoid valves 12 and 13 of the suspensions 3 and 4 on the front and rear wheels, respectively. suspension 3,
All suspension characteristics of No. 4 are returned to the soft state.

Furthermore, as shown in Fig. 7a, even though switching signals K and L were output to switch the suspension characteristics from hard to soft for both front and rear wheel suspensions 3 and 4, the rear wheel suspensions were not switched. Due to an abnormality in the soft signal C ₁ or D ₁ from the switch 53, or an abnormality in the step motor 9 or solenoid valve 13 in the rear wheel suspension 4, the suspension characteristics of the rear wheel suspension 4 are switched to soft. If it doesn't work,
Since the energization to the rear wheel side changeover switch 53 is not stopped, the detection signal N is fed back to the control logic section 51 from the current detection circuit 56 on the energization circuit 53a to the switch 53. In this case as well, since the front wheel side is in the soft state and the rear wheel side is in the hard state, the control logic unit 51 sends the hard signal A ₂ to the front wheel side and rear wheel side changeover switches 52 and 53 as shown in FIG. 7b. Switching signals K and L to output ~D ₂
Output. As a result, both the front and rear wheel suspensions 3 and 4 are returned to their hard state.

In this way, even if an abnormality occurs in the control system, the suspension characteristics of the suspension are prevented from becoming soft on the front wheels and hard on the rear wheels.

Here, the above control can be summarized in a flowchart as shown in FIG. 8.

That is, when the driving state of the vehicle detected by the sensors 15 to 18 changes or the manual switch 19 is operated, the control logic section 51
First, in step _S1 , it outputs switching signals K and L so that the suspension characteristics correspond to the changed state, and in step _S2 , it outputs an energization signal J for operating the changeover switches 52 and 53. . Then, in steps _S3 and _S4 , the current flowing to the changeover switches 52 and 53 is detected, and it is determined whether or not there is an abnormality.If there is no abnormality, control is continued in step _S5 . In this case, if there is an abnormality in the current flowing to the front wheel side changeover switch 52, that is, if the front wheel suspension 3 does not switch from soft to hard,
Switching signals K and L to soften both front and rear wheel suspensions 3 and 4 according to steps S ₆ to S ₈
At the same time, the energization signal J is outputted again to soften both the front and rear wheels, and then the control of the entire system is stopped. Conversely, when there is an abnormality in the current flowing to the rear wheel side changeover switch, that is, when the rear wheel suspension 4 does not switch from hard to soft, follow steps _S9 to _S11 to change the front and rear wheels. Switching signals K and L for hardening both side suspensions 3 and 4 and energizing signal J are output, and control of the entire system is stopped. This prevents the front wheels from becoming soft and the rear wheels from becoming hard.

Note that as the turning sensor 16 in the above embodiment, an acceleration detection sensor that detects so-called lateral G, a steering angle sensor that detects the steering angle of a steering wheel, or the like is used. In addition, the brake sensor 17
As the start sensor 18, a switch that detects depression of the brake pedal or an acceleration detection sensor that detects vertical G is used, and as the start sensor 18, an acceleration detection sensor that detects vertical G is used.

Further, in the above embodiments, the suspension characteristics are adjusted for both the damper and the spring, but the suspension characteristics of only one of them may be controlled.

As described above, according to the present invention, in a suspension whose suspension characteristics are variably controlled according to the driving condition of the automobile or by manual operation,
Even if an abnormality occurs in the control system, the front wheel suspension is prevented from becoming soft and the rear wheel suspension is hard. This prevents the steering characteristics from becoming oversteer due to the suspension characteristics being in the above-mentioned state, thereby ensuring the driving stability of the vehicle.

[Brief explanation of the drawing]

All drawings show embodiments of the present invention.
Figure 1 is a control system diagram, Figure 2 is a vertical sectional view showing the specific structure of the suspension, Figure 3 is an enlarged vertical sectional view of its main parts, and Figure 4 is the main part taken along the line shown in Figure 2. FIG. 5 is a block diagram of the controller, FIGS. 6 and 7 are time charts showing the operation of the controller, and FIG. 8 is a flow chart. DESCRIPTION OF SYMBOLS 1... Front wheel, 2... Rear wheel, 3, 4... Suspension means (suspension), 8, 9, 12, 13... Adjustment means (8, 9... Step motor, 12, 13... Solenoid valve), 14... Controller.

Claims (1)

[Claims] 1. A suspension comprising suspension means for suspending a vehicle body on the front wheels and rear wheels, adjustment means for changing the suspension characteristics of the suspension means, and a controller for operating the adjustment means, wherein the controller A state in which the side suspension characteristic is soft and the rear wheel side suspension characteristic is hard is detected and either a hard signal that makes both the front and rear wheels hard or a soft signal that makes both the front and rear wheels soft is applied to the adjustment means. An automobile suspension configured to output an output.