JPH0534963Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electronically controlled suspension device that can reduce nose dive that occurs in a vehicle body during braking.

2. Description of the Related Art An electronically controlled suspension device has been proposed that improves riding comfort by electronically controlling the damping force of the shock absorber and the spring constant of the air spring in each suspension unit of an automobile. In such an electronically controlled suspension system, it is desired to more effectively prevent pitching of the vehicle body during braking.

Therefore, as shown in U.S. Pat. No. 3,124,368, for example, the internal pressure of the fluid springs of each wheel is increased in order to bias the vehicle body in the opposite direction to the acceleration, depending on the magnitude of longitudinal acceleration acting on the vehicle body. 2. Description of the Related Art Suspension devices are known that actively reduce nose dive of a vehicle body through control. However, although the suspension device shown in this U.S. patent is configured to control the supply and discharge of fluid to the fluid spring according to the magnitude of the acceleration, the acceleration sensor that detects the acceleration is not suitable for driving on rough roads, etc. In some cases, even if the device is not actually in a deceleration state, a signal indicating that the device is in a deceleration state may be momentarily output, resulting in a malfunction of the device. Furthermore, this conventional device is configured to supply fluid to the fluid springs of the front wheels and discharge fluid from the fluid springs of the rear wheels during braking, but depending on the vehicle, due to the characteristics of its weight distribution, the front There are some vehicles in which the rear section only sinks and shows little movement, and if this conventional device is applied to such vehicles, the problem arises that the vehicle body posture becomes unnatural when braking and when braking is released. Furthermore, the above-mentioned conventional device routes the output of the accelerometer via a servo control amplifier forming part of the pitch control computer.
The signal is configured to be transmitted to a servo mechanism, and the servo mechanism is configured to transmit the fluid control valve.
Therefore, since a servo mechanism is used, not only is the device expensive, but also its adjustment, maintenance and inspection are labor-intensive operations.

This idea was made in consideration of the above points,
It is an object of the present invention to provide an electronically controlled suspension device which can reduce the nose dive that occurs in the vehicle body during braking and can significantly reduce the above-mentioned problems.

Hereinafter, an electronically controlled suspension device according to an embodiment of the invention will be described with reference to the drawings. In Figure 1, S _FR is a suspension unit for the right front wheel of a car, S _FL is a suspension unit for the left front wheel, S _RR is a suspension unit for the right rear wheel, and S _RL is a suspension unit for the left rear wheel. . Each suspension unit
Since S _FR , S _FL , S _RL , and S _RR have the same structure, only the structure of the suspension unit S _RL is shown. Suspension unit S _RL consists of main air spring chamber 11, sub air spring chamber 12, and shock absorber 1.
3. Consists of a coil spring (not shown) used as an auxiliary spring. Further, 14 is an actuator for switching the damping force of the shock absorber 13 to hard or soft, and 15 is a bellows. Note that the actuator 14
The main air spring chamber 11 and the auxiliary air spring chamber 12 are
Communication and non-communication are controlled, and the air spring constant is switched between hard and soft.

Further, 16 is an air cleaner. The air sent from the air cleaner 16 is sent to the dryer 18 via an outside air cutoff solenoid valve 17. The air dried by the dryer 18 is compressed by a compressor 19 and stored in a reserve tank 21 via a check valve 20. Note that 191 is a compressor relay, and this relay 191 is controlled by a signal from a controller 36, which will be described later. The reserve tank 21 has air supply solenoid valves 221 to 224.
The main and auxiliary air spring chambers 1 of each suspension unit S _RL to S _FL are connected via the air supply piping 23 in which the
1 and 12. In addition, the main and sub air spring chambers 11 and 12 of the suspension units S _RL and S _RR
are connected by a communication pipe 25 in which a communication solenoid valve 241 is installed, and the main and sub air spring chambers 11 and 12 of the suspension units S _FL and S _FR are
are connected by a communication pipe 26 in which a communication solenoid valve 242 is interposed. In addition, the main and auxiliary air spring chambers 11 and 12 of each of the suspension units S _RL to S _FL are connected to exhaust solenoid valves 271 to 271.
274 is installed, the exhaust pipe 28, the check valve 29, the dryer 18, and the solenoid valve 1.
7. It is released to the atmosphere via the air cleaner 16. A piping 31 in which a solenoid valve 30 for selecting an air supply side flow path is interposed is arranged in parallel with the air supply piping 23 . Note that when the solenoid valve 30 is open, air also flows through the pipe 31, making it possible to supply a larger amount of air per unit time. Furthermore, a pipe 33 in which an exhaust side flow path selection solenoid valve 32 is interposed is arranged in parallel with the exhaust pipe 28 . Note that when the solenoid valve 32 is open, the piping 33
The air also flows through the air, making it possible to discharge a larger amount of air per unit time. Further, a hard/soft switching solenoid valve 34 is interposed between the air supply pipe 23 and the actuator 14. Further, the pressure of the compressed air stored in the reserve tank 21 is detected by a pressure switch 35.
The detection signal of this pressure switch 35 is sent to a controller 36. In addition, 37 is the communication pipe 2
5 and is connected to the rear wheel suspension unit.
This is a pressure switch that detects the internal pressure of the main and auxiliary air spring chambers 11 and 12 of S _RR and S _RL . A detection signal from this pressure switch 37 is sent to the controller 36. Further, 38F is a front vehicle height sensor 38R that is attached to the lower arm 39 on the front right side of the vehicle and detects the front vehicle height of the vehicle.
A rear vehicle height sensor is attached to a lateral rod 40 on the rear left side of an automobile and detects the rear vehicle height. Above vehicle height sensor 38F, 38R
A vehicle height detection signal output from the controller 36 is input to the controller 36. The sensors 38F and 38R have a Hall IC element and a magnet, one of which is attached to the wheel side, and the other to the vehicle body side, and detect the distance from the normal vehicle height level and the low or high vehicle height level, respectively. Further, 41 is a vehicle speed sensor that detects vehicle speed, and a detection signal output from this vehicle speed sensor 41 is input to the controller 36. Furthermore, 42 is a steering wheel angle sensor that detects the steering angle of the steering wheel 43, and this sensor 42 outputs a steering wheel steering angle detection signal to the controller 36. Further, reference numeral 44 denotes an acceleration (G) sensor as a vehicle body posture sensor that detects changes in the posture of the vehicle body, and this acceleration sensor 44 is designed to detect changes in the posture of the vehicle body such as pitch, roll, and yaw on the automobile spring. For example, when there is no acceleration, the weight is in a hanging state, and the light from the light emitting diode is blocked by the shielding plate.
By not reaching the photodiode, the absence of acceleration is detected. Then, when acceleration acts in the front and back, left and right, or up and down directions, the weight tilts or moves, and the acceleration state of the vehicle body is detected. Furthermore, 45 is a vehicle height selection switch that sets the vehicle height to high vehicle height (HIGH), low vehicle height (LOW), or vehicle height adjustment (AUTO), and 46 is a vehicle height selection switch that selects to perform attitude control to prevent the vehicle from rolling. This is an attitude control selection switch. The signals of the switches 45 and 46 are transmitted to the controller 36.
is input. Furthermore, numeral 47 is an oil pressure switch that detects whether the oil pressure of the engine oil has reached a predetermined value and the amount of oil pressure, and the oil pressure detection signal outputted from this oil pressure switch 47 is inputted to the controller 36. Further, 48 is a brake switch that detects the depression and amount of depression of the brake, and its detection signal is input to the controller 36. moreover,
An accelerator opening sensor 49 detects the opening of the accelerator, and an accelerator opening signal outputted from this sensor 49 is input to the controller 36.
Furthermore, 50 is an engine rotation speed sensor that detects the engine rotation speed, and this sensor 50 outputs an engine rotation speed signal to the controller 36. Furthermore, 51 is an ignition key, the operation signal of which is output to the controller 36. 52 is a gear position sensor that detects the gear position;
outputs a gear stage signal to the controller 36.

In addition, the above-mentioned solenoid valves 17, 221 to 2
24, 271 to 274, 30, and 34 are normally closed valves, and the solenoid valves 241 and 242 are normally open valves.

Next, the operation of this invention configured as described above will be explained. The controller 36 shown in FIG. 1 performs the processing shown in the flowchart of FIG. First, in step S1, it is determined whether or not rolling prevention of the automobile, that is, roll control is necessary. This is, for example, the acceleration sensor 4
If the lateral acceleration detected in Step 4 is equal to or greater than a predetermined value, it is determined that roll control is necessary, and the process proceeds to step S2, where roll control is performed.
This is the right suspension unit S _FR , S _RR.
Air is supplied to the main and auxiliary air spring chambers 11 and 12 of the left suspension units S _FL and S _RL , and the main and auxiliary air spring chambers 1 of the other side of the unit are supplied with air.
Roll control is performed by keeping the vehicle body horizontal by exhausting air from 1 and 12. If the above step S1 determines "NO", step S3
Then, it is determined based on the signal from the brake switch 48 whether the brake has been depressed. If it is determined in step S3 that the brake is depressed, the program proceeds to step S4, where it is determined whether or not the longitudinal acceleration detected by the acceleration sensor 44 is greater than or equal to the set acceleration. In other words, when you step on the brake, the deceleration (that is, negative acceleration) increases, but the magnitude of this acceleration increases according to the amount of brake pedal depression, and as a result, the height of the front of the car decreases, so-called It becomes a nose dive. If the determination in step S4 is ``YES'', the process advances to step S5. This step S5
, the front wheel air supply solenoid valves 223 and 224 are activated by a control signal from the controller 36.
is opened for a set control time T. Therefore, the vehicle height of the front wheels is biased in a direction to raise the vehicle height, and the vehicle body is kept substantially horizontal. Then, in step S6, t ₁
After the time delay, the process returns to step S1.

If the brake continues to be depressed, a determination of ``YES'' is made in step S3, and the process proceeds to step S4 again. When the brakes are pressed and the vehicle speed drops to a certain speed, the brakes are released, but when the brakes are released, the deceleration becomes smaller. In such a state, the determination is "NO" in step S4, and the determination is "NO" in step S7.
In other words, it is determined that the deceleration has changed below the set deceleration. Then, in step S8, the front wheel exhaust solenoid valves 273, 274 are activated by the control signal from the controller 36 for the set control time T.
will be held during Therefore, the front wheels are biased in the direction of lowering the height of the vehicle, and as a result, the vehicle body is kept substantially horizontal even though the deceleration is reduced and the front portion of the vehicle body tends to rise due to rebound of the load. Thereafter, the process is delayed for _t2 hours in step S9, and then returns to step S1.

Therefore, according to this embodiment, it is possible to extremely effectively reduce the nose dive that occurs in the vehicle body when braking, and moreover, for example, when driving on a rough road, the acceleration sensor is instantaneously activated even though the vehicle is not actually braking. 4
Even if the brake switch 48 outputs a signal indicating a deceleration state, if the brake switch 48 does not output the signal, air supply and exhaust control for reducing nose dive will not be executed, so the problems of the conventional device described above are significantly reduced. It has the effect of being able to do it. In addition, the control in this embodiment is performed by controlling the air supply solenoid valves 223 and 22.
4 and the exhaust solenoid valves 273, 274 are opened for a set control time T at the timing mentioned above to adjust the amount of air in the air spring chamber of the front wheel. 224, 273, 274
can be made into a simple on-off valve without requiring any complicated servo mechanism, thereby solving the problems of the conventional device described above. Furthermore, since air supply and exhaust control to reduce nose dive is performed only in the air spring chambers of the front wheels, it is possible to reduce the amount of noise during braking, especially in vehicles where the front of the vehicle only sinks during braking and the rear of the vehicle hardly shows any movement. This has the effect of extremely effectively reducing nose dive without causing any unnatural changes in the posture of the vehicle body.

By the way, if the brake depression is small, the deceleration is small, so steps S4 → S7 → S1 → S3
→The process of S4 is repeated and steps S5 and S6
The attitude control that is performed in .

In addition, by providing delays of _t1 and _t2 in steps S6 and S8, even if there is a change in acceleration within _t1 hour after the brake is depressed and air is supplied to the front wheels for a certain period of time, the front wheels The structure is such that air is not exhausted from the front wheels, and even if there is a change in acceleration within _t2 hours after the front wheels have been exhausted for a certain period of time, air supply to the front wheels is not performed. As a result, even when the brakes are operated in small increments in a very short period of time, for example, it is possible to eliminate the problem of repeatedly executing air supply and exhaust control in the same direction.

As detailed above, according to this invention, it is possible to extremely effectively reduce the nose dive that occurs in the vehicle body when braking, and also to detect acceleration instantaneously even when the vehicle is not actually braking, for example, while driving on a rough road. Even if the means outputs a signal indicating a deceleration state, if the brake detection means does not output a signal, the air supply/discharge control in the air spring chamber for reducing nose dive is not executed. This has the effect of significantly reducing the problems caused by. Further, the control of the present invention is configured to adjust the amount of air in the air spring chamber of the front wheel by opening the supply control valve and the discharge control valve on the front wheel side for a set control time T at the above-mentioned timing. Therefore, these supply control valves and discharge control valves can be made into simple opening/closing valves without any complicated servo mechanism, which also solves the problems of the conventional device described above. Furthermore, since air is supplied and discharged from the air spring chambers to reduce nose dive only to the front wheel air spring chambers, this is especially true for vehicles where the front of the vehicle only sinks during braking and the rear of the vehicle hardly exhibits any movement. Even in this case, the nose dive can be extremely effectively reduced without causing an unnatural change in the posture of the vehicle body during braking.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electronically controlled suspension device according to an embodiment of this invention, and FIG. 2 is a flowchart showing the operation of the embodiment. 14... Actuator, 16... Air cleaner, 18... Dryer, 19... Compressor,
21... Reserve tank, 221-224... Air supply solenoid valve, 241, 242... Communication solenoid valve, 271-274... Exhaust solenoid valve.

Claims (1)

[Scope of utility model registration request] a suspension unit provided at least on the left and right front wheels and each having an air spring chamber; an air supply device that supplies air to each air spring chamber of each suspension unit via a supply control valve;
An air exhaust device that exhausts air from each of the air spring chambers through the respective exhaust control valves, a brake detection means that detects whether the brake is activated or not, and an acceleration detector that detects longitudinal acceleration acting on the vehicle body. and when the brake detection means detects that the brake is activated and the acceleration detection means detects that the negative acceleration is equal to or higher than the set acceleration, the supply control valve on the front wheel side is set. control means for opening the exhaust control valve on the front wheel side for a set control time T when the negative acceleration is detected by the acceleration detection means to be less than the set acceleration; An electronically controlled suspension device characterized by: