KR100926235B1 - Electronically controled air suspension system and method for controlling height therein - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled air suspension system and a garage control method thereof. The system of the present invention provides a damper that adjusts damping force to absorb and cushion shocks and vibrations coming from the road surface, and compressed air between the vehicle body and the wheel axle. Air spring for supplying or exhausting air to control the height of the garage, an air circuit for supplying or exhausting compressed air to the air spring, and the height of the car according to the signal detected from the vehicle speed or the garage sensors installed in the vehicle. And an ECU that provides a control signal for adjusting the damping force to the damper while providing a control signal for adjusting the damper force. Therefore, the present invention can control the air spring according to the height control of the vehicle, and at the same time control the damping force of the damper can be prevented from reducing the ride comfort due to vehicle vibration or shock.

Electronically controlled air suspension system, damper damping force, air spring, ride comfort

Description

Electronically controlled air suspension system and its garage control method {ELECTRONICALLY CONTROLED AIR SUSPENSION SYSTEM AND METHOD FOR CONTROLLING HEIGHT THEREIN}

1 is a configuration diagram briefly showing an electronically controlled air suspension system according to the prior art,

2a and 2b is a graph showing the change in natural frequency according to the load in the coil spring and the air spring, respectively,

3a and 3b is a view showing an example of the control of the height of the garage and the down in the conventional electronically controlled air suspension system,

Figure 4 is a block diagram showing an electronically controlled air suspension system according to an embodiment of the present invention,

5 is a flowchart illustrating a garage control method of an electronically controlled air suspension system according to an embodiment of the present invention;

6A and 6B are graphs comparing the case where the damping force of the damper is partially adjusted and the case where the damper force is not adjusted as in the present invention when performing the garage control in the electronically controlled air suspension system;

7A and 7B are graphs illustrating a case where the damping force of the damper is consistently adjusted when the height control is performed in the electronically controlled air suspension system.

<Explanation of symbols for the main parts of the drawings>

10: sensor / input unit 20: ECU

30: variable damper 40: air circuit

50: air spring

The present invention relates to an electronically controlled suspension system, and more particularly, to an electronically controlled air suspension system and a garage control method thereof suitable for improving ride comfort and heightening garage height control in a vehicle equipped with an air spring. will be.

In general, the electronically controlled suspension system of a vehicle is to improve the driving stability and turning characteristics while absorbing the impact from the road surface to improve the riding comfort, and there is an air suspension system provided in a large vehicle such as a bus.

The air suspension system uses an air spring that utilizes the elasticity of compressed air between the body (or frame) and the wheel axle, so it can absorb flexible vibrations and obtain flexible elasticity, providing excellent ride comfort and regulating compressed air pressure. By using it, it is possible to keep the car height constant regardless of the load, and to cope with the high quality of the vehicle, it is recently applied to the recreational vehicle.

1 is a configuration diagram briefly showing an electronically controlled air suspension system according to the prior art.

Referring to FIG. 1, the conventional electronically controlled air suspension system includes a sensor / input unit 100, an electrical circuit unit (ECU) 110, a variable damper 120, an air circuit 130, and a plurality of sensors and switches. Air spring 140 and the like. Here, the air spring 140 serves to absorb the impact of the road surface and support the load applied to the vehicle body, and may be installed in the variable damper 120 in one piece or in a separate type. For example, in the case of the front wheel, the air spring 140 and the variable damper 120 are integrally formed, and in the case of the rear wheel, the air spring 130 and the variable damper 120 are separated.

The sensor / input unit 100 includes a height sensor, a vertical acceleration sensor, a steering sensor, a speed sensor, a throttle sensor, a brake detection sensor, a manual / automatic switch, and the like. To pass).

The ECU 110 controls ride, roll, dive, and squat of the vehicle according to a sensor or switch signal (vertical acceleration, brake, etc.) detected from the sensor / input unit 100. A control signal is generated to adjust the damping force of the variable damper 120 softly or hardly by performing a calculation. At this time, the soft damping force of the damper shows a relatively low damping force, and the hard damping state shows a relatively high damping force.

The ECU 110 generates a control signal for adjusting the air of the air spring 140 mounted on the front wheel, the rear wheel, the left or the right wheel by comparing the height of the garage and the target height measured by the sensor / input unit 100. .

The variable damper 120 absorbs vibrations or shocks received by the axle from the road surface while driving the vehicle and improves ride comfort, and secures proper driving force in response to a change in vehicle attitude, thereby providing stability from the ECU. The control signals are received to control the driving of actuators (stepping motors, etc.) of each wheel according to the damper damping force value applied to the four wheels.

The air circuit 130 supplies and waits for a compressor that sucks compressed air from the atmosphere and exhausts working air into the atmosphere, an air tank in which high pressure compressed air is stored, and compressed air from the air tank to the air spring 140. And a solenoid valve having an opening and closing function of exhausting the furnace.

The electronically controlled air suspension system according to the prior art controls the vehicle body height by calculating a signal detected by the sensor / input unit 100 in the ECU 110 to supply air or exhaust air of the air spring. In addition, the signal detected by the sensor / input unit 100 is calculated from the road surface by adjusting the damping force of the variable damper 120 softly or hardly by performing calculations for the ride comfort, roll, dive, and squat control of the vehicle. Shock and vibration are absorbed and buffered quickly.

2A and 2B are graphs illustrating changes in natural frequencies according to loads in the coil spring and the air spring, respectively.

In contrast to the graphs of FIGS. 2A and 2B, the electronically controlled air suspension system has a lower natural frequency than the coil spring mounted in the general electronically controlled suspension system and sinks in comparison to the increased mass during loading or when a large number of passengers are on board. The vehicle's ride quality is improved by maintaining a constant natural frequency by increasing the air spring constant for adjusting the height of the vehicle while maintaining a constant garage height.

3A and 3B are diagrams showing control examples of the height of the garage and the height of the garage in the conventional electronically controlled air suspension system.

Conventional electronically controlled air suspension system adjusts the garage. When the vehicle cannot be leveled due to passenger boarding or cargo loading, the current garage detected by the garage sensor is controlled by supplying or exhausting the wheel air spring to the target garage. Level it up. At this time, the target garage can be changed by the driver's manual / automatic switch operation of the vehicle and can be changed automatically according to the vehicle condition.

For example, as shown in FIG. 3A, when the vehicle travels below the vehicle speed of V0 during the T0 time, the electronically controlled air suspension system raises the garage to a target (Low → Nor) at a low height. And if the vehicle is traveling at V1 or higher speed for T1 time, the electronically controlled air suspension system lowers the garage from the high height to the target (Nor → Low).

As shown in FIG. 3B, when the road surface state detected by the vertical acceleration sensor is determined to be rough road (On), the height of the garage is maintained from normal to high (Normal → High) for a predetermined time T1.

However, since the electronically controlled air suspension system according to the related art controls only the air supply or the exhaust of the air spring when controlling the height of the garage, there is a problem that the riding comfort is reduced due to the vibration or shock of the vehicle according to the height control of the vehicle. . In addition, the conventional electronically controlled air suspension system has a limitation in that the precise garage control function cannot be performed because the damping force of the damper is consistently maintained in a soft or hard state during the garage control process.

In order to solve the limitations and the problems of the prior art as described above of the present invention, by controlling the air spring in accordance with the height control of the height in the vehicle and at the same time by controlling the damping force of the damper to reduce the ride comfort due to vehicle vibration or impact The purpose is to provide an electronically controlled air suspension system that can be prevented.

It is another object of the present invention to provide a garage control method of an electronically controlled air suspension system which can increase control accuracy by hardly adjusting the damping force of a damper temporarily at a control start time and a control end time of a part of the overall garage control time. .

In order to achieve the above object, the present invention provides a damper for adjusting the damping force to absorb and cushion the shock and vibration coming from the road surface; An air spring for supplying or exhausting compressed air between the vehicle body and the wheel axle to control the height of the garage; An air circuit for controlling the supply or exhaust of the compressed air to the air spring; And supplying or exhausting compressed air to the air spring according to a control signal for adjusting the garage when the detected garage is not the same as the target garage when the vehicle speed signal detected from the vehicle speed sensor or the garage sensors installed in the vehicle is equal to or greater than the set speed. And at the same time, an ECU that hardly adjusts the damping force of the damper of the suspension system.

The method of the present invention for achieving the above object comprises the steps of determining whether the detected garage is equal to the target garage when the detected vehicle speed signal is greater than or equal to the set speed; If the garage is not the same as the target garage, supplying or exhausting compressed air to an air spring according to a control signal for adjusting the garage, and at the same time hardly adjusting the damping force of the damper of the suspension system; And softly adjusting the reducing force of the damper when a set time elapses.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

Figure 4 is a block diagram showing an electronically controlled air suspension system according to an embodiment of the present invention. Referring to FIG. 4, an electronically controlled air suspension system according to an embodiment of the present invention includes a sensor / input unit 10, an ECU 20, a variable damper 30, and an air circuit 40 including a plurality of sensors and switches. ), Air spring 50 and the like. In this case, the air spring 50 may be installed integrally or separately in the variable damper 30. For example, in the case of the front wheel, the air spring 50 and the variable damper 30 are integrally formed, and in the case of the rear wheel, the air spring 40 and the variable damper 30 is configured in a separate form.

The sensor / input unit 10 includes other sensors 11, such as a vertical acceleration sensor, a steering sensor, a throttle sensor, a brake detection sensor, a vehicle speed sensor 13, a garage sensor 15, and a manual / automatic switch 17. It transmits the signal detected by each sensor and switch to the ECU 20, including the.

The ECU 20 includes a ride comfort / roll / dive / squat control unit 21, according to a sensor or switch signal (vertical acceleration, brake, etc.) detected from the sensor / input unit 10 (ride), roll ( A control signal for performing roll, dive, and squat control, and softly or hardly adjusting the damping force of the variable damper 30 is generated. The ECU 20 includes the target calculator 23, the garage level adjusting unit 25, the attitude adjusting unit 27, the air control unit 29, and the like, when the vehicle speed measured from the sensor / input unit 10 is greater than or equal to the set vehicle speed. The garage height detected from the garage sensor and the target height are compared to generate a control signal for adjusting the air supply or exhaust of the air spring 50.

Furthermore, the ECU 20 of the present invention provides a control signal for adjusting the height of the garage to the air circuit 40 in accordance with the signal detected from the vehicle speed of the sensor / input unit 10 or the garage sensors 13, 15. A control signal is provided to the variable damper 30 to hardly adjust the damping force. If the height detected from the height sensor 15 is the same as the target height, a signal for stopping control of the air circuit 40 is provided and a control signal for hardly adjusting the damping force of the variable damper 30 is provided. In addition, the ECU 20 provides a control signal for hardly adjusting the damping force of the variable damper 30 for a predetermined time, and when the set time passes, the ECU 20 provides a control signal for softly adjusting the damping force of the variable damper 30.

The variable damper 30 is a device that absorbs and cushions vibrations or shocks received from a road surface while driving a vehicle to improve ride comfort, and secures driving stability by securing appropriate ground force in response to a change in vehicle attitude. In response to the control signals provided from the control unit, the driving of the actuator (stepping motor, etc.) of each wheel is controlled according to the damper damping force value.

The air circuit 40 is a circuit for controlling the supply or exhaust of compressed air to the air spring 50. The compressor 41 sucks compressed air from the atmosphere and exhausts working air into the atmosphere, and high pressure compressed air. And a solenoid valve 43 having an opening / closing function for supplying and exhausting compressed air from the air tank 45 to the air spring 50 to the atmosphere.

The air spring 50 controls the height of the garage as compressed air is supplied or exhausted between the vehicle body and the wheel axle (not shown).

5 is a flowchart illustrating a garage control method of an electronically controlled air suspension system according to an exemplary embodiment of the present invention. 4 and 5, a garage control method of an electronically controlled air suspension system according to an embodiment of the present invention is as follows.

When the vehicle speed detected by the vehicle speed sensor 13 of the sensor / input unit 10 is equal to or higher than the set vehicle speed, the ECU 20 determines that the vehicle is in a running state and performs the control of the present invention.

As a result of the determination in S10, when the vehicle is in the driving state, the ECU 20 calculates a preset target garage value through the target calculator 23. The height level adjusting unit 25 of the ECU 20 compares whether the height value detected by the height sensor 15 of the sensor / input unit 10 and the target height value calculated by the target calculating unit 23 are equal to each other. (S12)

As a result of comparison of S12, when the garage value of the current vehicle detected by the garage sensor 15 and the preset target garage value are not the same as each other, the garage level adjusting unit 25 of the ECU 20 determines whether the garage value is higher than the target garage value. (S14)

As a result of the determination in S14, when the garage value is not higher than the target garage value, the garage level adjusting unit 25 of the ECU 20 sends the garage level value to the air controller 29 to increase the garage value to the target garage. The air controller 29 provides a control signal for supplying air to the air spring 50 according to the garage level value, and the air circuit 40 supplies the solenoid valve 43 according to the control signal. By turning on) and supplying the high pressure compressed air of the air tank 45 to the air spring 50, the vehicle garage is raised to the target garage. (S16)

At the same time, the air control unit 29 of the ECU 20 sends a control signal for air spring operation to the ride comfort / roll / dive / squat control unit 21, and in this control unit 21, the damping force for hardly adjusting the damper damping force. The value is sent to the variable damper 30. (S20)

The ECU 20 determines whether the set time (for example, 30 seconds) has elapsed (S22), and when the set time has elapsed, the air control unit 29 releases a signal to the ride comfort / roll / dive / squat control unit 21. Send it. Then, the control unit 21 sends a damping force value for softly adjusting the damper damping force according to the release signal to the variable damper 30. (S24)

If it is determined in S14 that the garage value is higher than the target garage value, the garage level adjusting unit 25 of the ECU 20 sends the garage level value to the air controller 29 to lower the garage value to the target garage. The air controller 29 provides a control signal to the air circuit 40 for exhausting the air of the air spring 50 to the atmosphere according to the garage level value, and the air circuit 40 according to the control signal has a solenoid. The valve 43 is turned on to exhaust the compressed air of the air spring 50 to the atmosphere through the compressor 41. (S18)

While proceeding to step S16, the air control unit 29 of the ECU 20 sends a control signal for air spring operation to the ride comfort / roll / dive / squat control unit 21, and the control unit 21 hardly adjusts the damper damping force. The damping force value is sent to the variable damper 30, and the ECU 20 performs the following steps. (S20 to S24)

On the other hand, when the garage value of the current vehicle detected by the garage sensor 15 and the preset target garage value in step S12 are equal to each other, the ECU 20 transmits the garage level value to the air controller 29 in the garage level adjustment unit 25. Send as 0. In response, the air controller 29 blocks the control signal for supplying or exhausting the air from the air spring 50 to the air circuit 40 (S26).

While proceeding to step S26, the air control unit 29 of the ECU 20 sends a control signal for air spring non-operation to the ride comfort / roll / dive / squat control unit 21, and this control unit 21 sets the damper damping force. The damping force value for hard adjustment is sent to the variable damper 30. (S20) And when the set time has elapsed, the comfort / roll / dive / squat control unit 21 softly adjusts the damper damping force as in step S24. The damping force value is sent to the variable damper 30. (S24)

Therefore, the electronically controlled air suspension system according to the present invention temporarily hardens the damping force of the variable damper 30 when the vehicle garage controls the garage by supplying or exhausting the compressed air of the air spring 50 to increase or decrease the target garage. By making the adjustment, the riding comfort of the vehicle occupant is improved. In addition, even when the vehicle garage is fitted to the target garage, the damping force of the variable damper 30 is temporarily hardened to improve the riding comfort of the vehicle occupant.

On the other hand, although not described in the drawings, when the manual switch 17 is turned on by the manual / auto switch 17 of the sensor / input unit 10, the electronically controlled air suspension system of the present invention is placed in the manual mode. While the above-described control method is performed only when the switch is switched on and the manual switch 17 is turned on, when the automatic switch 17 is turned on, the system of the present invention is switched to the automatic mode. The above-described control method is performed when the vehicle is driving at a speed higher than the set vehicle speed.

6A and 6B are views illustrating an example in which a damping force of a damper is adjusted as in the present invention when the height is controlled in an electronically controlled air suspension system and when it is not.

As shown in FIG. 6A, in the conventional electronically controlled air suspension system, overshoot occurs because the damper force of the damper is kept in a soft state when the measurement height is raised to the target height. As a result, after the garage control is completed, the difference with the target garage is shown.

However, as shown in FIG. 6B, in the electronically controlled air suspension system according to the present invention, the damping force of the damper is increased from the garage to the target garage in a soft state temporarily in a soft state at the start of the garage control and the end of the garage control. By changing to, it is possible to increase the garage control accuracy at the end of the garage control and to prevent the control shock applied to the occupant at the start of the garage control.

However, when the damping force of the damper is adjusted softly or hard consistently over the entire garage control time, rather than temporarily adjusting the damping force of the damper as in the present invention at the start and end of the garage control, the garage control accuracy is rather increased. It will result in dropping. 7A and 7B show a case in which the damping force is kept constant when performing the garage control in the electronically controlled air suspension system, for example, when the damping force is not adjusted (soft) as shown in FIG. 7A and the total garage control time as shown in FIG. 7B. It is a graph comparing the case where the damping force of the damper was adjusted (hard) over.

As shown in FIG. 7A, in the conventional electronically controlled air suspension system, similarly to FIG. 6A, even when an overshoot occurs when the measured garage is raised to the target garage, the damper force of the damper is kept soft so that the shock caused by the garage adjustment is maintained. The vibration is transmitted to the vehicle body, resulting in poor ride comfort.

In addition, as shown in FIG. 7B, if the damper damping force is hardly adjusted over the entire garage control time, the time required for the garage control is increased by reducing the overall garage control speed, which is more than the level required by the damping force. The high pressure is filled inside the air spring so that after the pneumatic supply valve is shut off, the compressed air expands again to stop garage control at a much higher level (d) than the target garage. In this case, additional garage control is performed as needed, which adversely affects the overall garage control.

In the present invention, in order to solve the problems of Figs. 6A, 7A, and 7B as described above, as shown in Fig. 6B, temporarily at a garage control start point and a garage control end point, which are a part of the overall garage control time. By adjusting the damping force of the damper hardly, the height of the garage control is increased and the impact of the garage control is minimized.

As described above, the present invention has the effect of preventing the ride comfort caused by the vibration or shock of the vehicle by controlling the air spring according to the height control of the vehicle and simultaneously controlling the damping force of the damper. In addition, the present invention has the effect of improving the control accuracy by hardly adjusting the damping force of the damper temporarily at the control start time and control end time, which is a part of the overall garage control time.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (8)

In the electronically controlled air suspension system, A damper that adjusts the damping force to absorb and cushion shocks and vibrations coming from the road surface; An air spring for supplying or exhausting compressed air between the vehicle body and the wheel axle to control the height of the garage; An air circuit for controlling the supply or exhaust of the compressed air to the air spring; And When the vehicle speed signal detected from the vehicle speed sensor or the garage sensors installed in the vehicle is equal to or higher than the set speed, the compressed air is supplied or exhausted to the air spring by a control signal for adjusting the garage if the detected garage is not the same as the target garage. And an ECU which provides a control signal for hardly adjusting the damping force of the damper. The ECU controls to hardly adjust the damping force of the damper during a predetermined time period at each of the garage control start time and the garage control end time during all sections controlling the garage because the detected garage and the target garage are not the same. And a control signal for softly adjusting the damping force of the damper except for the set time. delete delete In the control method of the electronically controlled air suspension system, Determining whether the detected garage is equal to the target garage when the detected vehicle speed signal is greater than or equal to a set speed; As a result of the determination, when the detected garage is not the same as the target garage, the compressed air is supplied or exhausted to the air spring according to a control signal for adjusting the garage, and the hardening damping force of the damper of the suspension system is adjusted. Providing a control signal for Here, the detected garage and the target garage are not the same, so that the damping force of the damper is hardly adjusted during the set time at each of the garage control start time and the garage control end time in all sections controlling the garage. And controlling the damping force of the damper softly, except for the set time. delete delete delete delete

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