JP4853259B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control technology including a vehicle height adjustment mechanism.

  In general, a vehicle having a function of adjusting a vehicle height in accordance with a road surface state or a traveling characteristic is known. For example, in a wheel having an air spring in each wheel, the vehicle height can be adjusted by increasing or decreasing the amount of air in the air spring.

  When the pressure of the air spring is increased and the vehicle height is increased, the wheel base becomes shorter than the normal state, so that a rotational force is generated to rotate the front wheels backward and the rear wheels forward. At this time, if the brake is applied and the movement of the front and rear wheels is restricted, an excessive force is applied to each member due to the stroke load of the absorber, so if the operation is continued as it is, each part of the vehicle may be damaged, Inconveniences such as taking time to adjust the vehicle height may occur.

In order to prevent such a situation, Patent Document 1 discloses a vehicle height adjusting device configured to release braking of the front wheels by the front wheel braking device when the pressure in the air spring is increased. Further, Patent Document 2 discloses a parking brake device that releases the braking force of the front wheels or the rear wheels by the parking brake forcible releasing means when the vehicle height is adjusted in a state where the braking force is applied to all the wheels by the parking braking means. It is disclosed.
JP-A-7-237530 JP 2000-142340 A

  However, if the braking force is simply released, the vehicle may start to move during vehicle height adjustment. In addition, when the driver steps on the service brake (foot brake) himself, the rotation of the front and rear wheels is restricted even if the parking brake is released.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for reducing the burden on each part of the vehicle when the vehicle height is adjusted.

  One embodiment of the present invention is a vehicle control device. The device includes a vehicle height adjusting means that adjusts the vehicle height by changing the distance between the vehicle body and the wheel, and is installed between the sprung and unsprung parts of the vehicle, and a braking means that brakes the wheel. Braking force setting means for reducing the braking force generated by the braking means so as to allow rotation of wheels during execution of vehicle height adjustment by the vehicle height adjusting means, and inclination measuring means for measuring the inclination of the road surface on which the vehicle is located And comprising. The braking force setting means sets a different braking force according to the magnitude of the road surface inclination measured by the inclination measuring means.

  According to this aspect, the front wheel or the rear wheel can be rotated by reducing the braking force when adjusting the vehicle height. Since the braking force at this time is set according to the magnitude of the road surface inclination, the vehicle is prevented from moving during the vehicle height adjustment. In this state, if the distance between the vehicle body and the wheel is changed by the vehicle height adjusting means, the front wheel or the rear wheel rotates a little to absorb the change in the distance between the wheel bases. Will not be added. Further, since no extra force is consumed, the vehicle height adjustment can be executed quickly.

  The braking means may include both a service brake and a parking brake. As a result, even when the driver spontaneously brakes during vehicle height adjustment, it is possible to reduce the braking force and reduce the effect on vehicle height adjustment.

  The braking force setting means may release braking by both the service brake and the parking brake when the slope measuring means determines that the road surface is flat. If the road surface is flat, there is little concern that the vehicle will start to move during the vehicle height adjustment, and therefore the braking force may not be generated in the vehicle.

  The braking force setting means may maintain the braking by the parking brake and set the braking force of the service brake to a predetermined target value when it is determined by the inclination measuring means that the road surface is inclined. When the road surface is inclined, the vehicle is prevented from moving by the parking brake, and the service brake is released so that the wheel can be rotated during the height adjustment.

  The braking force setting means may release at least a service brake or a parking brake of a wheel on which vehicle height adjustment is executed. If the braking force is reduced only for the wheels on which the vehicle height adjustment is performed, there is no problem in the vehicle height adjustment, and it is not necessary to reduce the braking force unnecessarily.

  Monitoring means for monitoring the vehicle speed may further be provided, and the braking force setting means may increase the braking force of the service brake until the vehicle stops when the monitoring means detects that the vehicle has started to move. Even when the braking force of the service brake is reduced to a predetermined target value, the expected braking force may not be generated because the frictional force with the road surface is smaller than the expected value or the brake pads are worn. . Therefore, to ensure safety during vehicle height adjustment by monitoring the vehicle speed when the vehicle is on a sloping road surface and increasing the braking force until the vehicle stops when the vehicle starts to move. Can do.

  According to the present invention, in a vehicle provided with a vehicle height adjustment mechanism, the burden on each part of the vehicle when the vehicle height is adjusted is reduced.

  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. Hereinafter, the front wheels 14FR and 14FL and the rear wheels 14RR and 14RL of the vehicle are collectively referred to as “wheels 14”.

  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 vehicle body 12 is provided with an air pressure sensor 106 for detecting the air pressure in the air chamber of the air spring 16 for each wheel. The air pressure sensor 106 is of a type that measures the air pressure by electrically detecting the displacement of a thin film provided in a passage communicating with an air chamber, for example. A detection signal from the air pressure sensor 106 is sent to the ECU 100.

  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 valves 140 are provided corresponding to the respective wheels 14. The pneumatic control valve 140 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. As a result, air can be supplied into the air chamber 20 via the air supply line 190, and air can be discharged from the inside.

  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 valve 140, an exhaust valve 170, a high-pressure tank valve 168, and a motor 162 that drives the compressor 160. When the vehicle height adjustment switch 102 provided in the passenger compartment is turned on by the driver, the ECU 100 appropriately outputs a control signal to the control valve and the motor to exhibit or set an appropriate spring coefficient. Adjust to vehicle height.

  The wheel speed sensor 107 is provided in the vicinity of at least one of the wheels 14, detects the number of rotations of the wheel, and transmits it to the ECU 100. The acceleration sensor 108 is provided on the vehicle body, detects the longitudinal acceleration and the lateral acceleration of the vehicle, and transmits them to the ECU 100.

  FIG. 2 shows a configuration of a vehicle braking device 200 provided in the vehicle 10. The vehicle braking device 200 is a so-called electronically controlled brake (ECB), which detects the amount of operation of the brake pedal with a sensor and responds to a command from the ECU 100 that is issued in response to the operation of the brake pedal provided in the vehicle interior. Accordingly, the brakes can be operated independently of the four wheels. Hereinafter, the brake by the vehicle braking device 200 is also referred to as “service brake”.

  The brake pedal 72 is provided with a stroke sensor 46 for detecting the depression stroke. The master cylinder 74 pumps brake oil, which is hydraulic fluid, in response to the driver's depression operation of the brake pedal 72.

  One end of a brake hydraulic control conduit 76 for the right front wheel and a brake hydraulic control conduit 78 for the left front wheel are connected to the master cylinder 74, and these brake hydraulic control conduits exhibit the braking force of the right front wheel and the left front wheel, respectively. It is connected to wheel cylinders 15FR, 15FL for the right front wheel 14FR and the left front wheel 14FL. The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL are inserted in the middle of the brake hydraulic control conduits 76, 78 for the right front wheel 14FR and the left front wheel 14FL. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are open when not energized, and are switched to a closed state when a brake operation is detected (this is referred to as a “normally open type”).

  A right master pressure sensor 48FR and a left master pressure sensor 48FL for measuring master cylinder hydraulic pressures on the right front wheel 14FR side and the left front wheel 14FL side are provided in the middle of the brake hydraulic pressure control conduits 76 and 78, respectively. When the driver depresses the brake pedal 72, the stroke sensor 46 detects the amount of depression, but the master cylinder fluid is detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL assuming that the stroke sensor 46 has failed. The depressing operation force of the brake pedal 72 is also detected by measuring the pressure. The master cylinder hydraulic pressure is monitored by two pressure sensors from the viewpoint of fail-safe.

  The reservoir tank 26 is connected to the master cylinder 74, and the stroke simulator 24 that creates the operation amount and reaction force of the driver is connected via the on-off valve 23. The on-off valve 23 is a normally open solenoid valve that is open when de-energized and switches to open when the brake is operated. One end of a hydraulic supply / discharge conduit 28 is connected to the reservoir tank 26. The hydraulic supply / discharge conduit 28 is provided with an oil pump 34 driven by a motor 32. The discharge side of the oil pump 34 is a high-pressure conduit 30, and an accumulator 50 and a relief valve 53 are provided. The accumulator 50 accumulates brake oil that has been brought to a high pressure in the range of 14 to 22 MPa (hereinafter referred to as “control range”) by the oil pump 34. The relief valve 53 opens when the accumulator pressure is abnormally high, for example, a high pressure such as 25 MPa, and releases high-pressure brake oil to the hydraulic supply / discharge conduit 28.

  The high pressure conduit 30 is provided with an accumulator pressure sensor 51 that measures the accumulator pressure. An accumulator pressure, which is the output of the accumulator pressure sensor 51, is input to the ECU 100 described later, and the motor 32 is controlled so that the accumulator pressure falls within the control range.

  Each of the high-pressure conduits 30 is closed when not energized (this is referred to as “normally closed type”). When necessary, the high-pressure conduit 30 is an electromagnetic flow control valve that is used to increase the pressure of the wheel cylinder, that is, a linear valve. Via the pressure valves 40FR, 40FL, 40RR, 40RL, the wheel cylinder 15FR for the right front wheel 14FR, the wheel cylinder 15FL for the left front wheel 14FL, the wheel cylinder 15RR for the right rear wheel 14RR, and the wheel cylinder 15RL for the left rear wheel 14RL (hereinafter referred to as these) Are collectively referred to as “wheel cylinder 15”. Hereinafter, the reference numeral 40 is used to collectively refer to the pressure increasing valves 40FR, 40FL, 40RR, and 40RL.

  Disc brakes are provided on the right front wheel 14FR, the left front wheel 14FL, the right rear wheel 14RR, and the left rear wheel 14RL of the vehicle, and the brake pads are pressed against the disc by driving the wheel cylinders 15FR, 15FL, 15RR, and 15RL, respectively. In order to demonstrate the braking power.

  The right front wheel wheel cylinder 15FR and the left front wheel wheel cylinder 15FL are hydraulically fed and discharged via normally closed pressure reducing valves 42FR and 42FL, which are electromagnetic flow control valves used for pressure reduction when necessary, that is, linear valves. Connected to conduit 28. Further, the wheel cylinder 15RR for the right rear wheel and the wheel cylinder 15RL for the left rear wheel are connected to the hydraulic supply / discharge conduit 28 via normally open pressure reducing valves 42RR and 42RL, respectively. Hereinafter, when the pressure reducing valves 42FR, 42FL, 42RR, and 42RL are collectively referred to, reference numeral 42 is used.

  Near the right front wheel, left front wheel, right rear wheel, and left rear wheel wheel cylinders 15FR, 15FL, 15RR, 15RL, the right front wheel, the left front wheel, the right rear wheel, Pressure sensors 44FR, 44FL, 44RR, 44RL for the left rear wheel are provided.

  The ECU 100 controls the electromagnetic open / close valves 22FR and 22FL, the open / close valve 23, the motor 32, the four pressure increasing valves 40FR, 40FL, 40RR, and 40RL, and the four pressure reducing valves 42FR, 42FL, 42RR, and 42RL. The ECU 100 includes an arithmetic unit using a microcomputer, a ROM that stores various control programs, and a RAM that is used as a work area for data storage and program execution.

  Although not shown in detail, the arithmetic units include pressure sensors 44FR, 44FL, 44RR, 44RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively, in the wheel cylinder 15FR of the right front wheel. Pressure signal, pressure signal in the left front wheel wheel cylinder 15FL, pressure signal in the right rear wheel wheel cylinder 15RR, pressure signal in the left rear wheel wheel cylinder 15RL (hereinafter, generally referred to as wheel cylinder hydraulic pressure signal) Is input). Further, a signal indicating the depression stroke of the brake pedal 72 (hereinafter referred to as a stroke signal) is transmitted from the stroke sensor 46 to the arithmetic unit, and a signal indicating the master cylinder hydraulic pressure is transmitted from the right master pressure sensor 48FR and the left master pressure sensor 48FL ( A signal indicating the accumulator pressure (hereinafter referred to as an accumulator pressure signal) is input from the accumulator pressure sensor 51.

  The ROM of the ECU 100 stores a predetermined braking control flow. The calculation unit calculates the target braking force of the vehicle based on the stroke signal and the master cylinder hydraulic pressure signal, calculates the target wheel cylinder hydraulic pressure of each wheel based on the calculated target braking force, and calculates the wheel cylinder hydraulic pressure of each wheel. The pressure increasing valve 40 and the pressure reducing valve 42 are controlled so that becomes the target wheel cylinder hydraulic pressure.

  Although not shown, each wheel 14 of the vehicle 10 is also provided with a known parking brake. The parking brake is a so-called electronic parking brake (EPB), and braking force is generated in the parking brake in response to a command from the ECU 100 issued in response to an operation of a parking brake switch provided in the vehicle interior. . Since the parking brake is a well-known technique, further explanation is omitted.

  FIG. 3 is a functional block diagram showing the configuration of the ECU 100. Each block shown here can be realized in hardware by an element and a mechanical device including a computer CPU and memory, and in software by a computer program or the like. It is drawn as a functional block to be realized. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The vehicle speed measurement unit 110 calculates the vehicle speed based on the wheel speed signal from the wheel speed sensor 107. The inclination measuring unit 112 obtains the inclination angle of the road surface based on the longitudinal acceleration and lateral acceleration signals from the acceleration sensor 108.

  The vehicle height control start determination unit 116 determines whether or not the vehicle is stopped when the vehicle height adjustment switch 102 is turned on. When the vehicle is stopped, it is determined whether the road surface is flat or sloped based on the inclination angle of the road surface. For example, if the inclination angle is less than a predetermined threshold (for example, 1 degree), it is determined as a flat ground, and if it is more than that, it is determined as a slope.

  The brake setting unit 118 determines whether or not the shift lever of the transmission is at the parking (P) position. When the vehicle is not in the parking position, the vehicle height adjustment may be stopped, or the shift control unit 122 may be instructed to automatically move the shift lever to the parking position. The driver may be instructed by voice or the like to put the shift lever in the parking position. Subsequently, a predetermined target braking force is selected according to the inclination angle of the road surface. This target braking force is determined to be small enough to allow a slight amount of rotation of the wheels for each road inclination angle so as not to affect the response speed of the vehicle height control, and to prevent the vehicle from moving during vehicle height adjustment. Value of braking force applied. This target braking force can be determined by experiments or simulations using an actual vehicle.

The brake setting unit 118 instructs the service brake control unit 124 to reduce the braking force of the service brake to the target braking force. In addition, the brake setting unit 118 instructs the parking brake control unit 126 to release the parking brake if it is flat and to activate the parking brake if it is a slope. As a result, even when the driver spontaneously brakes during vehicle height adjustment, it is possible to reduce the braking force and reduce the effect on vehicle height adjustment.
In the case of a slope, the above target braking force is preferably set in consideration of the braking force generated by the parking brake.

  When the service brake and the parking brake are controlled by the brake setting unit 118, the vehicle height adjusting unit 120 adjusts the vehicle height using the vehicle height adjusting device described above.

  When it is determined that the road surface is a slope, the vehicle speed monitoring unit 114 receives the vehicle speed during the vehicle height adjustment and monitors the vehicle so as not to move. When it is detected that the vehicle speed is not zero and the vehicle starts to move, the vehicle speed monitoring unit 114 instructs the brake setting unit 118 to stop the vehicle. The brake setting unit 118 instructs the service brake control unit 124 to increase the braking force until the vehicle stops.

FIG. 4 is a flowchart of vehicle control according to the present embodiment.
When the vehicle height adjustment switch 102 is turned on (Y in S10), the vehicle height control start determination unit 116 determines whether or not the vehicle speed is 0 km / h, that is, whether or not the vehicle is stopped ( S12). If the vehicle is not stopped (N in S12), this flow is terminated. If the vehicle is stopped (Y in S12), the vehicle height control start determination unit 116 determines whether the road surface is flat or sloped (S14).

  If the road surface is flat (Y in S14), after confirming that the shift lever is in the parking position (S16), the brake setting unit 118 releases the service brake and the parking brake (S18). This is because if the road surface is flat, the vehicle is less likely to move during the vehicle height adjustment, and therefore it is not necessary for the vehicle to generate a braking force. However, for safety, the service brake may not be completely released and may be set so that a slight braking force is generated. Thereafter, the vehicle height adjustment unit 120 starts vehicle height adjustment (S20). When the vehicle height adjustment is completed, it is preferable that the brake setting unit 118 quickly activates the parking brake again.

If the road surface is a slope (N in S14), the brake setting unit 118 confirms that the shift lever is in the parking position (S22), and then applies the braking force of the service brake to a predetermined value while operating the parking brake. The target braking force is reduced (S24). Thus, when the road surface is inclined, the parking brake is actuated to prevent the vehicle from moving, and the service brake is lowered as much as possible so that the wheel can be rotated during the vehicle height adjustment. When the inclination angle is relatively small, the vehicle brake can be prevented from being started only by the parking brake, so that the service brake may be released.
Thereafter, the vehicle height adjustment unit 120 starts vehicle height adjustment (S26). The vehicle speed monitoring unit 114 continues to monitor whether the vehicle starts to move. When the vehicle moves (Y in S28), the brake setting unit 118 increases the braking force of the service brake and stops the vehicle (S30). If the vehicle does not move (N in S28), this flow ends.

  As described above, according to the present embodiment, the front wheel or the rear wheel can be rotated during the vehicle height adjustment by reducing the braking force to a predetermined target braking force. Therefore, when the distance between the vehicle body and the wheel is changed by the vehicle height adjusting means, the front wheel or the rear wheel rotates a little to absorb the change in the distance between the wheel bases, so that extra force is applied to each part of the vehicle. There is nothing. In general, when the vehicle height adjustment is executed in a state where the brake is applied, the movement in the circumferential direction of the wheel is restricted and the grounding point does not move, so that the response of the vehicle height control is deteriorated. In this embodiment, there is no such influence.

  Further, since the target braking force is set according to the magnitude of the road surface inclination, it is possible to prevent the vehicle from moving during the vehicle height adjustment. Therefore, the vehicle height can be adjusted without impairing the safety of the vehicle.

The present invention has been described based on the embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art.
The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  The reduction of the braking force of the brake does not have to be performed on all the wheels of the vehicle, and may be performed only on the wheels that are being subjected to the vehicle height control. If the braking force is reduced only for the wheels on which the vehicle height adjustment is performed, there is no problem in the vehicle height adjustment, and it is not necessary to reduce the braking force unnecessarily.

It is a mimetic diagram of a four-wheeled vehicle provided with a vehicle control device concerning one embodiment of the present invention. It is a figure which shows the structure of the vehicle braking device with which a vehicle is equipped. It is a functional block diagram which shows the structure of ECU. It is a flowchart of vehicle control according to this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ECU, 102 Vehicle height adjustment switch, 107 Wheel speed sensor, 108 Acceleration sensor, 110 Vehicle speed measurement part, 112 Inclination measurement part, 114 Vehicle speed monitoring part, 116 Vehicle height control start determination part, 118 Brake setting part, 120 Vehicle height adjustment Part, 122 shift control part, 124 service brake control part, 126 parking brake control part.

Claims (3)

Vehicle height adjusting means that adjusts the vehicle height by changing the distance between the vehicle body and the wheel that is interposed between the sprung and unsprung portions of the vehicle,
Braking means for braking the wheel;
Braking force setting means for reducing the braking force generated by the braking means so as to allow rotation of wheels during execution of vehicle height adjustment by the vehicle height adjusting means;
An inclination measuring means for measuring the inclination of the road surface on which the vehicle is located,
The braking force setting means releases braking by both the service brake and the parking brake when the slope measuring means determines that the road surface is flat during the vehicle height adjustment, and the slope measuring means When it is determined that the vehicle is inclined , the vehicle control device is configured to maintain the braking by the parking brake and set the braking force of the service brake to a predetermined target value . The vehicle control device according to claim 1 , wherein the braking force setting means releases at least a service brake or a parking brake of a wheel on which vehicle height adjustment is executed. A monitoring means for monitoring the vehicle speed;
The braking force setting means, if the vehicle starts moving is detected by the monitoring means during execution of the vehicle height adjustment, claim vehicle is characterized by increasing the braking force of the service brake to stop 1 The vehicle control device described in 1.

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