JPS59186708A - Suspension for automobile - Google Patents

Abstract

PURPOSE:To secure running stability in an automobile, by preventing a suspension from coming into a state that the front wheel side is soft whereas the rear wheel side is hard when anything trouble happens in a suspension system, in case of the said suspension which variably controls the suspension characteristic according to car driving conditions. CONSTITUTION:In the case where a suspension system at the front wheel side fails to normally operate whereas a suspension system at the rear wheel side operates normally when select signals K and L are outputted to each of front- and- rear-wheel-side select switches 52 and 53 from a control logic part 51 in order to select a suspension characteristic in suspension systems at both front and rear wheels from soft to hard, the select switch 52 at the front wheel side does not complete its select motion to 'hard' so that a continuous rating current still remains energized. This trouble is detected by a current detecting circuit 55, transmitting a trouble detection signal M to the control logic part 51. With this constitution, the control logic part 51 outputs these select signal K and L having a soft signal outputted to each of switches 52 and 53, thus the suspension characteristic of each suspension is brought back to a state of being soft.

Description

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

It is already known that the spring constant and Kumper damping rate of springs constituting the suspension of an automobile, that is, the suspension characteristics of the suspension, can be changed in accordance with driving conditions. 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 reduced by 1 relative to the front wheel side. An invention has been disclosed regarding a vehicle suspension characterized in that the steering characteristic is an acid steering characteristic, and the damping force relationship at low speeds is opposite to that at high speeds, resulting in neutral steering characteristics or oversteer characteristics. This is intended to simultaneously provide straight-line stability at high speeds and turning maneuverability at low speeds.

However, as mentioned above, when the suspension characteristics of the front and rear wheels are switched to heart 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 more likely to sway sideways, or causing dangerous phenomena such as the vehicle turning more than expected when steering. .

The present invention has focused on the above points, and has developed a suspension system in which the suspension characteristics are variably controlled according to driving conditions, so that 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. When the roller detects a state in which the suspension characteristics of the front wheels are soft and the suspension characteristics of the rear wheels are hard, a hard signal is sent to indicate that both the front and rear wheels are hard, or a software that sets both the front and rear wheels to soft 1.] ~ signals are configured to output one of them to the adjustment means. According to such a configuration, even when an abnormality occurs in the control system, the front wheels are prevented from changing from soft 1 to the rear wheels, and this relationship in suspension characteristics improves the running stability of the vehicle. This will prevent sexual deterioration and the risks associated with it.

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 are respectively provided with suspensions 3, 3, 4.4 for suspending the vehicle body. Each of these suspensions 3, 3, and 4.4 is composed of a coil spring 5, a damper 6, etc., and an air chamber 7, but the damping rate of the tamper 6 can be switched to two stages by the configuration described below. The front wheel suspension 3 is the actuator that performs this switching.
The suspension 4 on the rear wheel side is equipped with a step motor 8, and the suspension 4 on the rear wheel side is equipped with a step motor 9, respectively. Further, the air chamber 7 is connected to the accumulator 11 via a pipe 10, and the air chamber 7 and the accumulator 1 are connected to each other via a pipe 10.
1, there is a solenoid valve 12 for the front suspension 3, and a solenoid valve 12 for the rear suspension 4.
3 are installed respectively.

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 electromagnetic valve 12, and a drive signal C is sent to the step motor 9 in the rear suspension 4. Similarly, a controller 14 is provided which outputs drive signals to 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.
A turning signal F from the turning sensor 16 that detects the turning of the automobile, a brake signal G from the brake signal sensor 17 that detects the operation of the brake, a starting signal H from the starting sensor 18 that detects the starting of the automobile, and further The manual operation signal (2) from the manual switch 19 is configured to be manually operated.

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

As shown in FIG. 2, the mounting number plate 21 and the elastic body 22
Suspension 3 (
4) includes an upper case 23 that forms the air chamber 7 and a lower case 2 that is movable up and down relative to the case 23.
4, the lower end of the upper case 23 and the lower case 24
The upper end portions of the two cases 23 and 24 are connected to each other by a rolling tire flam 25, and a seal member 26 is provided that partitions the insides of both cases 23 and 24. The lower case 24 further includes 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.
The inside is partitioned into an upper oil chamber 31 and a lower oil chamber 32.

Further, the lower end of the inner cylinder 28 is provided with valves 1 to 33, and a space between the inner cylinder 28 and the outer cylinder 27 is defined as a gap 34. Here, the main valve 30 is provided with a check valve 3a, as shown in an enlarged view in FIG. 3, to allow hydraulic oil to pass only from the upper oil chamber 31 to the lower oil chamber 32 side. extended side orifice 301
) and a contraction-side orifice 30d that allows hydraulic oil to pass only from the lower oil chamber 32 to the upper oil chamber 33 side by a check valve 30c.
3 and the lower case 24, that is, a damper 6 that damps vibrations between the vehicle body sides.

The piston rod 29 extending from the damper 6 is hollow, and a control rod 35 is rotatably inserted into the piston rod 29. This rod 35 is connected to the step motor 8 through a rotary key 36 engaged at its upper end.
9) is configured to be rotated by
Valve body 3 provided at the lower end of the control rod 35
7 and a valve case 38 provided at the lower end of the piston rod 29 constitute an orifice valve 39. That is, as shown in FIG. 4, a passage 38 that connects an upper oil chamber 31 and a lower oil chamber 32 formed in a cylindrical valve case 38.
a is blocked by the rotation of the valve body 37 fitted in the case 38, or the orifice 37 in the valve body 37 is
They are communicated by a. This allows the upper oil chamber 31 and the lower oil chamber 32, the expansion side orifice 30b or the contraction side orifice 3 of the main valve 30 to
0d and the orifice 30.
1] or 30d, the orifice 37a of the three orifice valves is also switched to a communicating state, and the damping rate of the damper 6 constituted by these is switched to two levels, ie, hard and soft.

Further, as shown in FIG. 2, spring receivers 40 and 41 are provided in the upper case 23 and the lower case 24, respectively, and the coil spring 5 is mounted between these, and the coil spring 5 and the air chamber 7 are connected to each other. The air inside the suspension 3
4) constitutes the spring. In that case, since the air chamber 7 is connected to the accumulator 11 via the vibrator 10 and the solenoid valve 12 (13) as described above, the solenoid valve 12
The amount of operating air acting as a spring is increased or decreased depending on whether (13) is closed or opened, and the spring constant is switched to two levels, large and small. As a result, the spring of the suspension 3 (4) is switched between hard and soft.

As shown in FIG. 2, brackets 1 to 42 are provided at the lower end of the lower case 24 to mount 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 15 and the turning sensor 1
6. Control logic unit 51 into which signals @F~■ from the brake sensor 17, the starting sensor 18, and one manual switch are input.
and drive signals A and B (soft signal △1) to the step motor 8 and solenoid valve 12 of the front wheel suspension 3, respectively.
．． B1 or hard signal △2. Drive signals C and D are sent to the front wheel side changeover switch 52 that outputs the signal B2), the step motor 9 of the rear wheel suspension 4, and the solenoid valve 13, respectively.
(Soft signal @ C1, D 1 or hard signal C2, D2
), a relay 54 that closes in response to the energization signal J from the control logic section 51 and energizes both the changeover switches 52.53, and an energization circuit 52a to the changeover switches 52.53. , 53a, and current detection circuits 55 and 56 respectively installed on the current detection circuits 55 and 53a. And control 8I! I! The section 51 outputs signals from the sensors and switches 15 to 15 to change the front wheel side and rear wheel side changeover switches 52 . 53
In contrast, L is output to the switching signal @, and in response to this, drive signals A to D, which are soft signals or hard signals, are output from the changeover switches 52 and 53. The current detection circuit 55.56 also includes a front wheel side and rear wheel side changeover switch 52.5.
3 is detected, and the detected signal is fed back to the control logic unit 51 as detection signals M and N.

Next, the operation of the embodiment described in "-" will be explained.

Assuming that the car is currently traveling 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 has not been operated, this state is indicated and each Signals E-I from sensors and switches 15-19
The controller 14 to which is input outputs soft signals A1-D1 as drive signals A-D to the step motors 8, 9 and solenoid valves 12-13 in the front and rear wheel suspensions 3-4. Therefore, in the suspension 3.4, the orifice valve 39 constituting the damper 6 has the passage 38a connected to the orifice 3 as shown in FIG.
7a, the damper 6 is in a state where the damping rate is small, and the solenoid valve 12.13 is in an open state, so that the air outlet 7 and the accumulator 11 are in communication. Therefore, the spring constant of the air spring constituted by these is 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.

Furthermore, 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 i< is output from the control logic section 51 to the front wheel side changeover switch 52 based on the signal F from the vehicle speed sensor 15. At the same time, the relay 54 is closed by the energization signal J, and the changeover switch 52 is energized. Therefore, the drive signal A output from the changeover switch 52.

B is the hard signal A2. B2, and accordingly, the step motor 8 of the front wheel suspension 3 rotates by a certain angle, the orifice valve 39 in the damper 6 is shut off, and the solenoid valve 12 is closed, and the air chamber 7 and the accumulator 11 are shut off. As a result, both the damper and the spring of the front wheel suspension 3 are in a heart state. As a result, the steering characteristics become understeer characteristics, and straight-line stability at high speeds is improved. Further, during turning or braking, etc.), the step motors 8, 9 and the solenoid valves 12, 12, 12, 12, 12, 12, 22, 23 for the front and rear wheel suspensions 3, 4 are controlled from both the front wheel side and rear wheel side changeover switches 52, 53 in the controller 14. Hard signals A2 to D2 are output to the suspensions 3 and 4, respectively, and the suspension characteristics of both the 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. 6(a), in order to switch the suspension characteristics of both the front and rear wheel suspensions 3.4 from soft to hard, the control logic section 51 sends a front wheel and rear wheel changeover switch 52, When L is output as a switching signal to switch 53 and an energization signal J is output to energize these switches 52 and 53, on the rear wheel side, predetermined hard signals C2 and B2 are output from the changeover switch 53. was output and the step motor 9 and solenoid valve 13 of the suspension 4 operated normally, but on the front wheel side, there was an abnormality in the hardware signal @A2 or B2 from the changeover switch 52, or these signals A2, Assume that B2 is normal, but there is an abnormality in the step motor 8 or the solenoid valve 12, and 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 energization to the rear wheel side changeover switch 53 is stopped when the changeover operation to the hardware mode is completed, but the energization state continues indefinitely to the front wheel side changeover switch 52 because the changeover operation to the hardware mode is not completed. will be done. This abnormality is caused by the energizing circuit 52a of the changeover switch 52.
It is detected by a current detection circuit 55 installed above 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 outputs soft signals Δ1 to D1 to the front wheel side and rear wheel side changeover switches 52 and 53, as shown in FIG. 6(b). In this manner, L is outputted as a switching signal, and an energization signal J is again outputted to operate these changeover switches 52 and 53. As a result, soft signals A1 to D1 are outputted from both changeover switches 52 and 53 to the step motors 8 and 9 and solenoid valves 12 and 13 of the front and rear suspensions 3 and 4, respectively. The suspension characteristics of No. 4 are all returned to the states of Soft No. 1.

In addition, as shown in FIG. 7(a), 2. Even though L was output as a switching signal to switch the suspension characteristics from hard to soft 1 for both the front and rear suspensions 3 and 4, the soft signal C1 or If there is an abnormality in Dl or the step motor 9 or solenoid valve 13 in the rear wheel suspension 4 does not allow the suspension characteristics of the rear wheel suspension 4 to be switched softly, the rear wheel side changeover switch 53 Since the energization of the pair is not stopped, the detection signal N is fed back to the control logic unit 511 from the current detection circuit 56 on the energization circuit 53a to the switch 53. In this case as well, the front wheels are soft and the rear wheels are hard, so the control logic unit 51
As shown in FIG. 7 (1)), L is output as a switching signal so that the front wheel side and rear wheel side changeover switches 52 and 53 output hard signals Δ2 to D2. As a result, the front and rear wheel suspensions are 3.1! Both I are returned to the hard state.

In this way, when 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 each of the sensors 15 to 18 changes or the manual switch 19 is operated, the control logic unit 51 first determines the suspension characteristics corresponding to the changed state in step S1. L is output to the switching signal @ so that the switching signal @ is outputted, and an energization signal J is outputted to operate the changeover switch 52, 53 in step S2. Then, in steps S3 and 84, the current applied to the changeover switch 52, 53 is detected, and it is determined whether or not there is an abnormality, and if there is no abnormality, control is continued in step S5. In this case, when there is an abnormality in the current flowing to the front wheel side changeover switch 52, that is, when the front wheel side suspension 3 does not switch from soft to hard, follow steps 86 to S8 to As well as outputting L as a switching signal for softening both wheels, the energization signal J is again output to soften both the front and rear wheels, and then 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 side suspension 4 cannot be switched from hard to soft, step $
In accordance with 9 to S11, L and the energization signal J are output to the switching signal for hardening both the front and rear wheel suspensions 3.4, and the control of the entire system is stopped. This results in
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.

Further, as the brake sensor 17, 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 embodiment 1, 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 variable controlled depending on the driving condition of the vehicle or manually (thus, the front wheel suspension is variably controlled), even if an abnormality occurs in the control system, the front wheel suspension is soft. and rear wheel side 1
The eggplant pension is no longer in a heart state. This prevents the steering characteristics from becoming oversteer due to the suspension characteristics being in the above-mentioned state.
The running stability of the car is ensured.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention; FIG. 1 is a control system diagram, FIG. 2 is a vertical cross-sectional view showing the specific structure of the suspension, and FIG. 3 is an enlarged vertical cross-sectional view of the main parts. Fourth
The figure is an enlarged cross-sectional view of the main part taken along the line IV--IV in Figure 2, Figure 5 is a block diagram of the controller, Figures 6 and 7 are time charts that do not show the action of the controller, 8th
The diagrams are also flowcharts 1 to 1. 1...Front wheel, 2...Rear wheel, 3.4...Suspension means (
8, 9, 12.13... Adjustment means (8, 9... Step motor, 12.13... Solenoid valve), 14... Controller Applicant: Toyo Kogyo Co., Ltd. No. 3 Figure 4 Figure 7q Figure 6 (a) Figure 7 (a) (b) (b')

Claims (1)

[Claims] (1) Suspension means for suspending the vehicle body on the front wheels and the rear wheels, respectively;
A suspension comprising an adjusting means for changing the suspension characteristics of the suspension means, and a controller for operating the adjusting means, wherein the controller has a soft suspension characteristic on the front wheel side and a soft suspension characteristic on the rear wheel side. is characterized in that it is configured to detect a state in which the front and rear wheels become hard and output either a hard signal for returning the front and rear wheels to hard or a soft signal for making both the front and rear wheels soft to the adjusting means. car suspension.