KR101130288B1 - Electronically controled suspension system and method for controlling anti-squat using the same - Google Patents

Abstract

The present invention relates to an air suspension and an electronically controlled suspension device, and the disclosed air suspension is installed between a vehicle body and an axle, and a damper that absorbs vibrations or shocks received from a road surface when the vehicle travels, and is installed coaxially outside the damper. A rubber piston coupled to the top of the air piston to act as an air spring, a cap coupled to the top of the rubber tube and coupled to the upper end of the piston rod of the damper, and a rubber to widen the pressure action volume of the air spring. A volume expander connected to the inside of the tube, and a volume control valve for opening and closing the connection between the inside of the rubber tube and the volume expander to determine the pressure action volume of the air spring, and the transverse motion may occur in a vehicle equipped with the air suspension. When the spring rate of the air spring is adjusted There is an advantage that can be stabilized.

Description

ELECTRONICALLY CONTROLED SUSPENSION SYSTEM AND METHOD FOR CONTROLLING ANTI-SQUAT USING THE SAME

1 is a configuration diagram of an air supply line of an air suspension vehicle according to the prior art;

2 is a cross-sectional view showing the structure of an air spring applied to the air suspension according to the present invention;

3 is a block diagram of an electronically controlled suspension device according to the present invention;

4 is a flowchart illustrating an anti squat control process using an electronically controlled suspension device according to the present invention;

Figure 5 is a timing diagram showing the waveform of the valve control signal output from the electronic control unit in the electronic control suspension apparatus according to the present invention.

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

10 damper 11 air piston

12: rubber tube 13: piston rod

14: cap 15: rubber bumper

16 volumetric expander 17 volumetric control valve

21: vertical acceleration sensor 22: vehicle speed sensor

23: steering angle sensor 30: electronic control unit

41: damper drive unit 42: air supply control unit

43: air spring volume adjustment unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air suspension, and more particularly, to an electronically controlled suspension device (ECS) capable of quickly and efficiently stabilizing the movement of a vehicle when a squat motion occurs in a vehicle equipped with the air suspension. system) and an anti-squat control method using the same.

In general, the suspension of the vehicle is provided in order to absorb the impact from the road surface to improve the riding comfort and to improve the driving stability and the turning characteristic, such an air suspension using air instead of the plate spring.

Since air suspension uses air spring that uses the elasticity of compressed air, it is possible to obtain flexible elasticity while absorbing even the fine vibration, so that the riding comfort is excellent and the height of the car is controlled regardless of the load by adjusting the compressed air pressure. It is possible to keep constant until, and corresponds to the luxury of the vehicle, which is recently applied to a leisure vehicle, the use is increasing rapidly.

FIG. 1 is a configuration of a supply line for explaining an anti-squat control process in an electronically controlled suspension device of an air suspension vehicle according to the prior art, and shows a squat motion in which the vehicle is moved forward when the vehicle is rapidly accelerated. The control is to stabilize the movement of the vehicle. That is, by installing an air spring between the body (frame) and the axle to allow the air spring to control the phenomenon that the vehicle is soared forward when the vehicle is accelerated.

A total of four air springs 3 are installed, a pair of front wheels 1 and a pair of rear wheels 2, which can receive compressed air from the air tank 5 via a connecting tube. The connecting pipe is provided with two leveling valves 4 for the front wheels and two for the rear wheels to adjust the amount of air in the air spring 3, thereby restoring the vehicle's behavior The up state) is adjusted.

On the other hand, the air spring 3 of the front wheel 1 is inflated using the air inside the high pressure tank when the squat motion that the vehicle is moving forward when the vehicle is rapidly accelerated, and the air spring 3 of the rear wheel 2 ) Is contracted by exhausting the internal air to the atmosphere, and stabilizes the movement of the vehicle through the operation of the front and rear wheels (1, 2) air spring (3). That is, when the vehicle accelerates rapidly, the air spring 3 of the front wheel 1 is supplied by using the air inside the high pressure tank to lift the front of the vehicle upward, and the air spring 3 of the rear wheel 2 is contracted. By lowering the back of the vehicle to stabilize the movement of the vehicle during rapid acceleration.

However, since the conventional air suspension does not have a fast response enough to respond to squat motion occurring in a short time due to the characteristics of the pneumatic equipment, the control effect is not large, and the occurrence of squat motion is terminated, and the general driving situation is returned. When it is necessary to return to the front wheel (1) to raise the rear wheel (2) is a long control time for balancing the front and rear there is a problem that can hinder the movement performance of the vehicle.

The present invention has been proposed to solve such a conventional problem, and its purpose is to control the spring rate of the air spring by adjusting the pressure action volume of the air spring applied to the air suspension during the squat motion of the vehicle. It is to provide a suspension device and an anti-squat control method using the same.

In an aspect of the present invention for realizing the above object, the electronically controlled suspension device includes a volume expander connected to the pressure action space to widen the pressure action volume of the air spring, and a connection state between the pressure action space and the volume expander. An air suspension having a volume control valve for opening and closing, an electronic control unit for generating a valve control signal by anti-squat control logic based on a vertical acceleration value detected by a longitudinal acceleration sensor of the vehicle, and in accordance with the valve control signal. And an air spring volume adjusting unit for adjusting the spring rate of the air spring by opening and closing the volume control valve to adjust the pressure action volume of the air spring.

According to another aspect of the present invention, an anti-squat control method using an electronically controlled suspension device includes a volume expander connected to the pressure action space to open and close a connection state between the pressure action space and the volume expander so as to increase the pressure action volume of the air spring. An anti-squat control method of an electronic control unit for controlling an air suspension having a volume control valve, comprising: calculating a control reference value based on a vertical acceleration or an engine output magnitude of a vehicle when a squat motion occurs while driving; Determining whether the reference value is greater than or equal to an upper threshold value, and if the control reference value is greater than or equal to an upper threshold value, closing the volume control valve mounted to the rear wheel (or the front wheel) of the air spring to close the volume control valve. Increase the spring rate, but the control threshold is lower threshold It falls below includes the step of opening the volume control valve of the rear wheels (or front wheels).

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. This embodiment allows for a better understanding of the objects, features and advantages of the present invention. However, the present invention is not limited to this embodiment.

2 is a cross-sectional view showing the structure of an air spring applied to the air suspension according to the present invention. Looking at the structure, the damper 10 is installed between the body and the axle to absorb the vibration or shock received from the road surface while driving the vehicle to improve the ride comfort, and the damper 10, which is a shock absorber coaxially to the outside of the damper 10 Cylindrical air piston 11 to be installed, the rubber tube 12 is air-tightly coupled to the upper end of the air piston 11 and acts as an air spring, the air-tightly coupled to the upper portion of the rubber tube 12 and the damper ( Cap 14 coupled to the upper end of the piston rod 13 of 10), an air port (not shown) for supplying the compressed air supplied from the air supply means (not shown) to the air piston 11, and the cap The rubber bumper 15 is fixed to (14) and absorbs the shock during compression of the piston rod 13, and is attached to the outside of the cap 14, the rubber tube 12 of the air spring to widen the pressure action volume of the air spring The volume expander 16 connected therein and the inside of the rubber tube 12 And it is configured to include a volume expander volume control valve 17 to determine the pressure acting volume of the air spring by opening or closing the connection between the (16).

The volume expander 16 greatly expands the internal pressure operating volume of the air spring in order to realize the natural frequency of the air spring at a lower natural frequency than the coil spring, and influences such as interference when mounted in a narrow space such as an engine room of a vehicle. The cap 14 is additionally mounted so as not to receive.

The air spring configured as described above is filled with the compressed air introduced through the airport (not shown) in the rubber tube 12, and the rubber tube (at the time of repeated movement of tension and compression of the piston rod 13 according to the running of the vehicle) 12) acts as a vibration spring to move up and down.

In addition, referring to FIG. 1, the air port (not shown) of the air spring is connected to the air tank 5, which is an air supply means, via a leveling valve 4, and a large load is loaded on the vehicle to compress the rubber tube 12. When compressed air is injected from the air tank 5, the rubber tube 12 is restored.

Then, in order to prevent the occurrence of a squat phenomenon in which the vehicle body 7 is lifted forward by centrifugal force when the squat motion occurs due to rapid acceleration of the vehicle, conventionally, the leveling valve 4 is controlled to control the compressed air of the air tank 5. Although the method of supplying / exhausting air to the air spring was used, in the present invention, the spring rate of the air spring is adjusted by opening and closing the volume control valve 17 to adjust the pressure action volume of the air spring. That is, the air spring at the rear of the vehicle body 7, that is, at the rear wheel, momentarily closes the volume control valve 17 to increase the spring rate by reducing the pressure action volume of the air spring, and on the opposite air spring, the volume control valve 17 is The momentary opening allows the pressure action volume of the air spring to be expanded by the volume expander 16, thereby lowering the spring rate to prevent the vehicle from being excessively heard.

The electronically controlled suspension device employing the air suspension as described above may be implemented as shown in the block diagram of FIG. 3. Looking at the configuration, the vertical acceleration sensor 21, the vehicle speed sensor 22, the steering angle sensor 23, the brake sensor 24, the throttle position sensor 25 attached to the upper body of each wheel to measure the behavior of each wheel ), A damper driver 41 for controlling the damping force of dampers provided between the vehicle body and each axle based on the damping force control signals of the electronic control unit (ECS ECU) 30 and the electronic control unit 30, and the electronic control unit ( The air spring on the basis of the valve control signal of the electronic control unit 30 and the air supply adjusting unit 42 for supplying or exhausting the compressed air of the air tank to the rubber tube of the air spring based on the air supply control signal of 30). It is configured to include an air spring volume adjusting section 43 for adjusting the spring rate of the air spring by opening and closing the volume control valve of the air spring to adjust the pressure action volume of the air spring.

In the electronically controlled suspension device configured as described above, the damper drive unit 41 displays the motion characteristics of the damper 10 in real time according to the damping force control signal generated by the electronic control unit 30 based on the information from the various sensors 21 to 25. Variable to improve ride comfort and adjustment stability. That is, the damper 10 is an endless variable damper having a variable valve attached to the side of the damper 10, and two damping control valves are installed in the variable valve bundle to separately control the damping force during the tension / compression stroke. .

The air supply control unit 42 generates an air supply control signal according to the information from the various sensors 21 to 25, and provides the air port (not shown) based on the air supply control signal. By filling the compressed air in the rubber tube 12 of the air spring to perform the function of the air spring that the rubber tube 12 moves up and down during the repeated movement of the tension and compression of the piston rod 13 according to the running of the vehicle Ensure vibration damping. In addition, when the rubber tube 12 is compressed due to a large load on the vehicle, compressed air is injected from the air tank 5 to restore the rubber tube 12.

On the other hand, the electronic control unit 30 is implemented with a control algorithm that performs the ride comfort control logic and anti-squat control logic. The ride comfort control logic adjusts the damping force mode to hard / soft through the tension variable valve of the damper 10 during the tension stroke in which the vehicle body is lifted, and soft / hard the damping force mode through the variable valve for compression in the compression stroke in which the vehicle body sinks. By implementing the sky-hook control by adjusting the, the vehicle movement is controlled to improve the riding comfort. The anti-squat logic is to suppress the squat movement of the vehicle by controlling the damping force of the damper 10 during rapid acceleration of the vehicle, and the vertical acceleration signal or throttle received from the vertical acceleration sensor 21 or the throttle position sensor 25. After the squat motion of the vehicle is determined based on the position signal, the acceleration value or the engine output magnitude of the vehicle is calculated based on the vertical acceleration signal or the throttle position signal, and the damper 10 is calculated based on the calculated acceleration value or engine output magnitude of the vehicle. Adjust the damping force. That is, the electronic control unit 30 closes the volume control valve 17 installed between the inside of the love tube 12 and the volume expander 16 when the acceleration value or the engine output magnitude of the vehicle becomes greater than or equal to the threshold value.

In addition, the electronic control unit 30, when anti-squat control logic determines the generation of longitudinal motion according to the driving direction of the vehicle, the volume control valve to prevent the occurrence of a squat phenomenon that the front of the vehicle is lifted by the centrifugal force A valve control signal for the control of 17 is outputted.

Then, the air spring of the rear wheel, which is the air spring volume adjusting unit 43 is pulled based on the valve control signal of the electronic control unit 30, closes the volume control valve 17 momentarily to reduce the pressure action volume of the air spring. Thereby increasing the spring rate, and temporarily opening the volume control valve 17 to the opposite air spring to expand the pressure action volume of the air spring by the volume expander 16, thereby lowering the spring rate to prevent the vehicle from being excessively lifted. .

In addition, in setting the threshold value for outputting the valve control signal in the electronic control unit 30 may have a variable value depending on the vehicle speed or other vehicle conditions. Frequent control due to hysteresis is determined by comparing the end point of the spring rate adjustment control of the air spring performed through opening and closing of the volume control valve 17 with other threshold values having a value slightly lower than the previously used threshold value. Can be prevented.

In order to help the understanding of the opening and closing process of the volume control valve 17 by the electronic control unit 30 will be described with reference to FIGS. 4 and 5.

Referring to the rapid acceleration situation of the vehicle in which the driver presses the pedal while driving (S400) and the acceleration of the vehicle is changed as follows.

Prior to the description, the electronic control unit 30 determines the upper threshold value UT and the lower threshold value LT for the anti squat control logic during the braking process of the vehicle, as shown in FIG. 5A.

First, while driving the vehicle, the electronic control unit 30 determines whether the squat motion is generated (S402). The determination of whether the squat motion is generated is determined based on the vertical acceleration signal or the throttle position signal input from the vertical acceleration sensor 21 or the throttle position sensor 25.

If a squat motion occurs in step S402, that is, the front part of the vehicle is lifted due to rapid acceleration of the vehicle, the electronic control unit 30 vertically (advances) the vertical acceleration sensor 21 of the vehicle as shown in FIG. The control reference value is calculated using the engine output magnitude calculated based on the vertical acceleration signal of the vehicle or the throttle position signal of the throttle position sensor 25 obtained from the step S404, and the control threshold value is set to the upper threshold value UT. If exceeded (S406), the electronic control unit 30 provides a volume valve control signal to the volume control valve 17 to close the two volume control valve 17 of the rear wheel (S408). When the volume control valve 17 is closed, the volume inside the air spring is reduced so that the air spring is compressed by the same stroke to have a greater reaction force than when the volume control valve 17 was previously opened. That is, when the volume control valve 17 is closed, the stiffness of the air spring becomes high.

If the volume control valve 17 is closed again when the control reference value falls below the upper threshold value (UT), excessively frequent valve control occurs when the input of the control reference value is maintained or vibrates near the threshold value. In order to prevent this, the lower threshold LT is applied. That is, even when the control reference value falls below the upper threshold value UT, the volume control valve that is closed when the control reference value falls below the lower threshold value LT is performed by performing step S408 to maintain the closed state. (17) is opened (S410, S412).

In the above description, but limited to one embodiment of the present invention, it is obvious that the technology of the present invention can be easily modified by those skilled in the art.

As an example, Figure 5 (b) has been described an embodiment of opening and closing any one of the volume control valves of the front and rear wheels to increase the rigidity of the air suspension when squat control is required, but only one volume control valve opening and closing control If you do, it may lead to vehicle instability. Therefore, as shown in FIG. 5C, when the squat control is required, all volume control valves of the front and rear wheels may be opened and closed to increase the rigidity of the air suspension for all the wheels, thereby stabilizing the movement of the vehicle.

Such modified embodiments should be included in the technical spirit described in the claims of the present invention.

As described above, the present invention is to adjust the spring rate of the air spring by adjusting the pressure action volume of the air spring applied to the air suspension using a quick response valve, when squat motion occurs in a vehicle equipped with the air suspension By adjusting the spring rate of the air spring it is possible to stabilize the movement of the vehicle quickly and efficiently.

Claims (9)

A volume expander connected to the pressure action space to widen the pressure action volume of the air spring, an air suspension having a volume control valve for opening and closing the connection between the pressure action space and the volume expander; An electronic control unit for generating a valve control signal by anti-squat control logic based on the vertical acceleration value detected by the longitudinal acceleration sensor of the vehicle, An air spring volume adjusting unit for adjusting the spring rate of the air spring by opening and closing the volume control valve in accordance with the valve control signal to adjust the pressure action volume of the air spring. , &Lt; / RTI & The electronic control unit The control reference value is calculated using the calculated engine power magnitude based on the vertical acceleration value, and when the calculated control reference value exceeds the preset upper threshold value UT, a valve control signal for closing the volume control valve is generated. Maintains the closed state of the volume control valve even when the calculated control reference value falls below an upper threshold value, and generates a valve control signal for opening the volume control valve when the control reference value falls below a preset lower threshold value. Electronically controlled suspension device, characterized in that. The method of claim 1, And the valve control signal of the electronic control unit is generated on the basis of an engine output value calculated based on a signal generated from the TPS of the vehicle. The method according to claim 1 or 2, And a threshold for outputting the valve control signal of the electronic control unit has a variable value depending on the vehicle speed or other vehicle conditions. The method of claim 1, The end point of the spring rate adjustment control of the air spring by the electronic control unit is determined by comparing with another threshold value having a lower value than the previously used threshold value. Anti-squat of the electronic control unit for controlling the air suspension with a volume expander connected to the pressure action space to widen the pressure action volume of the air spring, and a volume control valve for opening and closing the connection state between the pressure action space and the volume expander. As a control method, If a squat motion occurs while driving, calculating a control reference value based on the vertical acceleration of the vehicle or the magnitude of the engine output; Determining whether the control reference value is greater than or equal to a predetermined upper threshold value; As a result of the determination, when the control reference value is higher than or equal to the upper threshold value, the volume control valve mounted on the rear wheel (or the front wheel) of the volume control valve is closed to increase the spring rate of the air spring, wherein the control reference value is a lower threshold value. Opening the volume control valve of the rear wheel (or front wheel) when it falls below , &Lt; / RTI & The opening step Maintaining the closed state of the volume control valve even when the control reference value falls below the upper threshold value, and then opening the volume control valve according to a valve control signal generated when the control reference value falls below a predetermined lower threshold value. Anti-squat control method using an electronically controlled suspension device, characterized in that. The method of claim 5, The upper and lower threshold values are variable according to the vehicle speed or other vehicle conditions, characterized in that the anti-squat control method using an electronically controlled suspension device. The method of claim 5, After opening the volume control valve of the rear wheel (or front wheel), the threshold for spring rate adjustment control of the air spring uses another threshold value having a lower value than the previously used threshold value. Anti squat control method using device. The method of claim 5, The squat motion is generated, the anti-squat control method using the electronically controlled suspension, characterized in that determined based on the vertical acceleration value or the TPS value of the vehicle. The method of claim 5, And the spring rate of the air spring is adjusted by opening and closing the volume control valves of both the front and rear wheels to adjust the pressure action volume of the air spring when the control reference value has a value equal to or lower than a lower threshold value. Anti-squat control method using the suspension device.

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