JP2007099096A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the air from being bled excessively out of the chamber of an air spring when the vehicle height lowers. <P>SOLUTION: A vehicle height adjusting means has the air spring interposed between the sprung and unsprung parts of a vehicle and arranged generating a resilient force between the two parts by the chamber filled with air, whereby the vehicle height is adjusted by influx and outflow of the air to/from the chamber. Therein a control valve 142 is provided to control the influx and outflow of the air to/from the chamber 20 in conformity to the instruction for lowering or raising the vehicle height, while a pilot valve 144 is installed in the flow passage leading from the control valve 142 to the chamber 20 and set so as to close the flow passage at or below a predetermined pressure. When the vehicle height lowers and the internal pressure of the chamber 20 becomes at or below the predetermined level, the pilot valve 144 is closed to stop the air being exhausted from the chamber 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle control device, and more particularly to a control technique in a vehicle having means for adjusting the vehicle height.

  In general, an air spring can change its spring constant by adjusting the amount of air filled in the chamber. Further, the vehicle height can be adjusted by increasing or decreasing the amount of air in the chamber. In recent vehicles, it has been devised to make it easier for passengers to get on and off and to load and unload luggage by lowering the overall height of the vehicle body or lowering the height of the vehicle's cargo compartment when getting on and off or loading and unloading luggage. Has been.

If the vehicle body touches an obstacle such as a curb while the vehicle height is falling, air will be discharged from the air spring chamber until it reaches the target vehicle height. There is a problem that it takes time to increase the pressure in the chamber when raising the vehicle height. Therefore, Patent Document 1 discloses a technology in which, in a vehicle including an air spring device, when an obstacle is recognized when the height position of the vehicle is changed, the change is automatically terminated.
JP-A-11-91330

  However, in the said patent document 1, the apparatus which recognizes an obstruction is needed separately, and becomes a factor of a cost increase. Further, when there is an obstacle other than the part where the device for recognizing the obstacle is installed, the change of the vehicle height cannot be finished.

  This invention is made | formed in view of such a condition, The objective is to provide the technique which prevents excessive extraction of the air at the time of vehicle height fall in the vehicle provided with an air spring.

  One embodiment of the present invention is a vehicle control device. The device comprises a fluid spring interposed between the sprung and unsprung portions of the vehicle and configured to generate an elastic force between the sprung and unsprung by a fluid-filled chamber, Vehicle height adjusting means for adjusting the vehicle height by fluid flow into and out of the chamber, a control valve for controlling fluid flow into and out of the chamber in response to a vehicle height drop or rise command, and the chamber when the vehicle height is lowered And an excessive discharge preventing means for stopping the discharge of fluid from the chamber when the internal pressure becomes equal to or lower than a predetermined pressure.

  According to this aspect, when the pressure in the chamber of the fluid spring becomes equal to or lower than a predetermined pressure while the vehicle height is decreasing, the exhaust of the air from the chamber is stopped by the excessive discharge preventing means, so that the vehicle body touches the obstacle. Even when the lowering of the vehicle height is hindered by a cause such as, the exhaust of excessive air from the chamber is prevented.

  The excessive discharge preventing means may be a pilot valve that is disposed in a flow path that communicates the control valve and the chamber and is set to close the flow path at a predetermined pressure or lower. Alternatively, the excessive discharge prevention means includes a pressure sensor that detects a pressure in a flow path that communicates with the chamber, and closes the control valve when a detection value of the pressure sensor falls below a predetermined pressure. And a valve closing means for instructing to do so.

  ADVANTAGE OF THE INVENTION According to this invention, in the vehicle provided with an air spring, the excessive extraction of the air at the time of vehicle height fall can be prevented.

  FIG. 1 is a schematic diagram of a four-wheel vehicle 10 including a vehicle control device according to an embodiment of the present invention. In FIG. 1, the suspension device is shown in a plan view for the sake of simplicity of explanation, but in an actual vehicle, for example, a knuckle, a tie rod, It is configured by combining with other parts such as an upper arm and a lower arm in a known manner.

  An air suspension device configured by combining an air spring 16 and an absorber 18 is mounted between the vehicle body 12 and each wheel 14 of the vehicle 10. The air spring 16 is realized by filling the air chamber 20 formed so as to surround the absorber 18 with compressed air. The compressed air in the air chamber 20 acts as a spring and elastically supports the wheel 14 to prevent the impact of the wheel 14 from being directly transmitted to the vehicle body 12. Further, the vehicle height can be adjusted for each wheel 14 by changing the volume of the air chamber 20. The absorber 18 generates a damping force between the sprung and unsprung parts of the vehicle. In this specification, the position of a member supported by the air spring 16 is referred to as “sprung”, and the position of a member not supported by the air spring 16 is referred to as “unsprung”. That is, the sprung is on the vehicle body 12 side, and the unsprung is on the wheel 14 side. The air spring 16 and the absorber 18 are preferably integrally configured from the viewpoint of space saving, but may be provided separately.

  A vehicle height sensor 104 that detects the vehicle height at the wheel position is disposed in the vicinity of each wheel 14. The vehicle height sensor 104 may detect the relative distance between the vehicle body 12 and the wheel 14 by measuring the displacement of the link connecting the axle and the vehicle body, or the distance between the vehicle body and the road surface may be measured by a laser. It is also possible to measure with A detection signal of the vehicle height sensor 104 is sent to an electronic control device 100 (hereinafter referred to as “ECU 100”) provided in the vehicle body 12.

  The air chamber 20 of the air spring 16 is in communication with an air supply line 190. In the middle of the air supply line 190, air pressure control units 140 are provided corresponding to the respective wheels 14. The air pressure control unit 140 is electrically connected to the ECU 100. When the ECU 100 instructs the air pressure control unit 140 to inflow or discharge air, the air is supplied into the air chamber 20 of the air spring 16 via the air supply line 190, and the air is discharged from the inside. it can.

  The vehicle body 12 is provided with a compressor 160 for supplying compressed air to the air supply line 190. The motor 162 supplies power to the compressor 160. When the motor 162 rotates, air is taken in from the outside through the air inlet 164 and compressed by the compressor 160. The compressed air flows into the dryer 174. The dryer 174 contains a desiccant such as silica gel, and dries the air that has flowed in and supplies it to the air supply line 190.

  The vehicle body 12 may be provided with a high-pressure tank 166 that can store compressed air supplied from the compressor 160 and a high-pressure tank valve 168 that controls the flow of air into and out of the high-pressure tank. The high-pressure tank 166 is maintained at 700 to 800 kPa, for example, by sending compressed air from the compressor 160. By supplying compressed air from both the high-pressure tank 166 and the compressor 160 to the air supply line 190, the responsiveness when the air spring is pressurized can be improved. Therefore, if the capacity of the compressor 160 is sufficient, the high-pressure tank 166 may not be provided in the vehicle body 12.

  The air supplied from the dryer 174 flows into the air supply line 190 that communicates with the air chamber 20 via the check valve 178. The check valve 178 opens when air is supplied from the compressor 160 side, and flows air to the air supply line 190, but closes when air from the air supply line 190 flows. A throttle 176 is provided so as to bypass the check valve 178. The air from the air supply line 190 flows into the throttle 176 and is flown into the dryer 174 after the flow velocity is reduced. By doing so, moisture absorbed by the silica gel of the dryer 174 can be reduced. The air that has passed through the dryer 174 is discharged from the silencer 172 through the exhaust valve 170 to the outside of the vehicle.

  ECU100 performs control of the air spring 16 of each wheel. The ECU 100 is electrically connected to a pneumatic control unit 140, an exhaust valve 170, a high-pressure tank valve 168, and a motor 162 that drives the compressor 160. The ECU 100 appropriately outputs control signals to the air pressure control unit, the control valve, and the motor based on signals from various sensors and switches, and exhibits an appropriate spring coefficient or adjusts it to a set vehicle height.

  The vehicle height of the vehicle 10 is adjusted by the ECU 100 in accordance with a plurality of predetermined modes. For example, in conjunction with ignition off, the entire vehicle body is lowered to a vehicle height lower than normal (for example, 30 mm) to increase the boarding / exiting mode, or the rear wheel of the vehicle in conjunction with the opening of the hatch of the cargo compartment There is “Package mode” that makes it easy to load and unload luggage by lowering only the side. When executing any of the modes, the ECU 100 discharges air from the air chamber 20 of the air spring 16 until the value detected by the vehicle height sensor 104 of the wheel corresponding to each mode reaches the target vehicle height. The control unit 140 is controlled.

  A vehicle height selection switch 102 that allows the driver to select one of the above-described vehicle height modes prepared in advance, in addition to or in addition to interlocking with the ignition off or hatch opening as described above. You may provide in the vehicle interior of the vehicle body 12. FIG. This switch information is also input to the ECU 100. Also in this case, the ECU 100 controls the air pressure control unit 140 so that air is discharged from the air chamber 20 of the air spring 16 until the value detected by the vehicle height sensor 104 of the wheel corresponding to each mode reaches the target vehicle height. To do.

FIG. 2 shows a state of the vehicle 10 when the load mode (b) is executed from the normal vehicle height (a). As shown in FIG. 2 (b), when the vehicle height is decreasing, before the vehicle reaches the target vehicle height, a part of the vehicle body may come into contact with an obstacle 50 such as a curb stone, and the vehicle height may not further decrease. is there. At this time, since the ECU 100 discharges air from the air chamber 20 of the air spring 16 based on the detection value of the vehicle height sensor 104, if the vehicle height does not drop due to the obstacle 50, the air from the air chamber 20 Will continue to be discharged. Then, when the vehicle height is raised later, it is necessary to introduce the discharged air into the air chamber 20, so that it takes time to adjust the vehicle height and the load applied to the motor 162 that drives the compressor 160 also increases. End up.
Therefore, in this embodiment, means for preventing excessive discharge of air from the air chamber 20 of the air spring 16 when the vehicle height decreases is provided.

FIG. 3 shows a configuration of the air pressure control unit 140 shown in FIG. The pneumatic control unit 140 includes a control valve 142 and a pilot valve 144. The control valve 142 is a directional control valve that is electrically connected to the ECU 100 and can be switched between a valve open state and a valve closed state in accordance with a signal from the ECU 100. Thereby, air can be supplied into the air chamber 20 of the air spring 16 via the air supply line 190, and air can be discharged from the inside. The pilot valve 144 is disposed in a flow path that allows the control valve 142 and the air chamber 20 to communicate with each other, and is set to close the flow path at a threshold value _PT or less. That is, when the pressure in the vicinity of the pilot valve 144 is expressed as P _V , the pilot valve 144 is opened when P _V > P _T , and the pilot valve 144 is closed when P _V ≦ P _T.

When the occupant and luggage are not mounted on the vehicle 10 (that is, when the vehicle is empty) and the empty vehicle pressure generated in the air chamber 20 at normal vehicle height is P _E , the valve closing pressure P _{T of the} pilot valve 144 is Is set as follows.
P _T = P _E -p
Here, p is an adjustment value for taking a margin, and is preferably set to about 50 kPa.

If pressure in the air chamber 20 of the air spring 16 is below the bare pressure P _E, unless the body is not in contact with the obstacles, the vehicle height of the vehicle 10 should necessarily be reduced. Accordingly, the pressure P _V of the pilot valve vicinity is lower than the threshold value P _T with a margin from the bare pressure P _E are not occur during normal vehicle height adjustment. Therefore, when the pilot valve pressure P _V is equal to or less than the threshold value P _T, this could be a vehicle body is in contact with the obstacle, it is preferable to stop the discharge of air from the air chamber 20.

With the above configuration, when the pressure in the air chamber 20 falls below a predetermined pressure while the vehicle height is decreasing, the pilot valve 144 closes and the discharge of air from the air chamber 20 is stopped. Excessive air discharge from the air chamber 20 is prevented even when the vehicle height is prevented from lowering. Thereafter, when raising the vehicle height, after the control valve 142 is opened, when the pressure of the air supply line 190 reaches the threshold value _PT due to the compressed air from the compressor 160 or the high-pressure tank 166, the pilot valve 144 is The valve can be opened to introduce air into the air chamber 20.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. Hereinafter, such modifications will be described.

Modification 1
FIG. 4 shows another configuration of the pneumatic control unit 140 shown in FIG. In this configuration, the air pressure control unit 140 is electrically connected to the ECU 100 and can be switched between a valve open state and a valve closed state according to a signal from the ECU 100, and the control valve 142 and the air spring 16. And a pressure sensor 146 installed in a passage communicating with the air chamber 20. The detection value of the pressure sensor 146 is supplied to the ECU 100.

In this configuration, the detection value of the pressure sensor 146 is denoted as _{P S.} The ECU 100 opens the control valve 142 to discharge air from the air chamber 20 of the air spring 16 when the vehicle height decreases. The ECU 100 uses the threshold value P _T described above to maintain the control valve 142 in an open state when P _S > P _T and closes the control valve 142 when P _S ≦ P _T. To command.

  As described above, when the pressure in the air chamber 20 becomes equal to or lower than a predetermined pressure when the vehicle height is lowered, the control valve 142 is closed and the discharge of air from the air chamber 20 is stopped. Excessive air discharge from the air chamber 20 is prevented even when the lowering of the air is prevented. Thereafter, when raising the vehicle height, the ECU 100 may open the control valve 142 and then introduce compressed air into the air chamber 20 from the air supply line 190.

Modification 2
FIG. 5 shows still another configuration of the pneumatic control unit 140 shown in FIG. In this configuration, a pair of wheels, that is, the front wheel or rear wheel air pressure controllers 140A and 140B have control valves 148A and 148B that can be switched between a valve open state and a valve closed state in accordance with a signal from the ECU 100, respectively. However, one pressure sensor 150 is shared. The pressure sensor 150 is installed in a passage communicating the control valves 142A and 142B and the air supply line 190. The detection value of the pressure sensor 150 is input to the ECU 100.

In this configuration, the detection value of the pressure sensor 150 is denoted as _{P S.} The ECU 100 opens the control valves 148A and 148B to discharge air from the air chambers 20A and 20B of the air spring 16 when the vehicle height decreases. At this time, the ECU 100 uses the threshold value P _T described above to maintain the control valves 148A and 148B in the open state when P _S > P _T and when P _S ≦ P _T , Commands 148A, 148B to close.

Alternatively, when the vehicle height decreases, the ECU 100 first opens the control valve 148A to discharge air from the air chamber 20A, and then opens the control valve 148B to discharge air from the air chamber 20B. Also good. The ECU 100 uses the threshold value P _T described above to maintain the control valve 148A or 148B in an open state when P _S > P _T , and when P _S ≦ P _T , the control valve 148A Or you may instruct | command to close 148B.

  In the case of the first modification, the same number of pressure sensors as the air springs are required. However, in the second modification, it is sufficient to provide one pressure sensor for one set of wheels, and the cost can be reduced. . If the pressure sensor shown in FIG. 5 is shared by the control valves 148 corresponding to the four wheels mounted on the vehicle, the cost can be further reduced.

It is a mimetic diagram of a vehicle provided with a vehicle control device concerning one embodiment of the present invention. It is a figure which shows the mode of a vehicle when the package mode of (b) is performed from the normal vehicle height of (a). It is a figure which shows the structure of the air pressure control part shown in FIG. It is a figure which shows another structure of the air pressure control part shown in FIG. It is a figure which shows another structure of the air pressure control part shown in FIG.

Explanation of symbols

  10 vehicle, 12 vehicle body, 16 air spring, 18 absorber, 20 air chamber, 50 obstacle, 100 ECU, 102 vehicle height selection switch, 104 vehicle height sensor, 140 air pressure control unit, 142, 148 control valve, 144 pilot valve, 146, 150 pressure sensor, 148 control valve, 160 compressor, 162 motor, 166 high pressure tank, 168 high pressure tank valve, 170 exhaust valve, 190 air supply line.

Claims (3)

A fluid spring interposed between the sprung and unsprung portions of the vehicle and configured to generate an elastic force between the sprung and unsprung by a fluid-filled chamber; Vehicle height adjusting means for adjusting the vehicle height by inflow and outflow,
A control valve that adjusts the flow of fluid into and out of the chamber in response to an instruction to lower or raise the vehicle height;
Excessive discharge preventing means for stopping the discharge of fluid from the chamber when the pressure in the chamber becomes lower than a predetermined pressure when the vehicle height decreases;
A vehicle control device comprising:   The over-discharge prevention means is a pilot valve that is disposed in a flow path that communicates the control valve and the chamber, and is set to close the flow path at a pressure equal to or lower than a predetermined pressure. The vehicle control device according to 1.   The excessive discharge preventing means closes the control valve when the pressure sensor detects a pressure in a flow path communicating with the chamber and a detected value of the pressure sensor is equal to or lower than a predetermined pressure. The vehicle control device according to claim 1, further comprising valve closing means for commanding.

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