JP2003220962A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vehicle which changes the steering characteristic of a vehicle so that a driver may not have uncomfortable feeling even if an air pressure of the wheel changes. <P>SOLUTION: The control device for a vehicle is characterized in that it is equipped with an air pressure alarm system 6 which detects air pressure of each wheel 2 respectively and emits an alarm when either air pressure of the wheel deviates from a prescribed value, and a characteristics changing means 6 which changes the control characteristics of the power steering for the vehicle according to the air pressure of the wheels. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device, and more particularly to a vehicle control device that changes control characteristics relating to steering of a vehicle in accordance with wheel air pressure.

[0002]

2. Description of the Related Art There is known an automobile equipped with an air pressure alarm system which measures the air pressure of a wheel and issues an alarm to inform the driver when the measured air pressure deviates from a predetermined range.

[0003]

When the air pressure of the wheels changes, the tire gripping force on the road surface changes and the running characteristics relating to the steering of the vehicle also change. That is, even if the steering wheel is operated in the same manner, the degree (size) of changing the direction of the vehicle, the timing, and the like change. Such changes may give the driver a feeling of strangeness and may hinder stable driving.

The present invention has been made in consideration of such a situation, and provides a vehicle control device for changing the steering characteristics of a vehicle so that the driver does not feel uncomfortable even if the air pressure of the wheels changes. The purpose is to provide.

[0005]

According to the present invention, an air pressure alarm system for detecting the air pressure of each wheel and issuing an alarm when the air pressure of any wheel deviates from a predetermined range, and the air pressure of the wheel. And a characteristic changing unit that changes the control characteristic of the power steering apparatus of the vehicle according to the above.
The change of the control characteristic is preferably performed so as to suppress the change of the steering feeling due to the decrease of the air pressure, for example.

According to the present invention having such a structure,
In addition to issuing an alarm when the air pressure of wheels (tires) drops, etc., the steering characteristics of the vehicle are changed in accordance with changes in air pressure. Changes in steering feeling are suppressed, and vehicle safety is further improved.

According to another aspect of the present invention, a characteristic changing means is provided for detecting the air pressure of each wheel and changing the control characteristic of the power steering device of the vehicle in accordance with the air pressure. A vehicle controller is provided.
It is preferable to change the control characteristics so as to suppress a change in steering feeling such as a phase delay due to a decrease in air pressure.

According to the present invention having such a structure,
Since the steering characteristic of the vehicle is changed according to the change of the air pressure, the change of the running stability and the change of the steering feeling of the vehicle due to the change of the air pressure of the wheels are suppressed, and the safety of the vehicle is further improved.

According to another preferred aspect of the present invention, the characteristic changing means changes the control characteristic such that the lower the air pressure, the greater the assistance provided by the power steering device. When the air pressure of the wheels decreases, the steering wheel operation becomes heavy and the reaction of the vehicle to the steering wheel operation becomes slow. Therefore, by increasing the assist of the power steering device, the change in the steering feeling due to the decrease in the air pressure is suppressed. .

According to another preferred aspect of the present invention, the characteristic changing means changes the control characteristic such that the lower the air pressure is, the higher the convergence characteristic of the power steering device is. Since the convergence property is enhanced, the reaction of the vehicle to the operation of the steering wheel is sharpened, so that the reaction of the vehicle is suppressed from being sluggish due to the decrease in the air pressure of the wheels.

According to another preferred aspect of the present invention, the characteristic changing means changes the control characteristic so that the assist by the power steering device becomes small when the air pressure of the rear wheels is relatively low. .

When the rear wheel air pressure is relatively low, the grip force on the rear wheel side is relatively low and the spin tendency is high. Therefore, the assist of the power steering device is reduced, and the air pressure on the rear wheel side is reduced. , The change in steering feeling is suppressed.

According to another preferred aspect of the present invention, the characteristic changing means controls the steering feeling in the left-right direction to be the same when the difference between the air pressures of the left and right wheels is a predetermined value or more. Change the characteristics. The grip of the outer wheel has a great effect on the turning of the vehicle. For this reason, the change in the steering feel due to the decrease in air pressure differs depending on whether the wheel whose air pressure has decreased is the turning inner wheel or the outer wheel. That is, steering feeling is different between right turn and left turn. Therefore, by changing the control characteristics of the power steering device as in the above-described aspect, the steering feeling in the left and right directions becomes the same, and the driver can drive without feeling discomfort.

According to another preferred aspect of the present invention, the characteristic changing means changes the control characteristic so as to reduce the assist by the power steering device when the air pressure suddenly drops.

According to this structure, even if the driver turns the "panic handle" when the air pressure is suddenly decreased due to a flat tire or the like, the assist of the power steering device is small, so that the reaction of the vehicle is slow. Therefore, abrupt changes in the running state of the vehicle are suppressed.

According to another preferred aspect of the present invention, the characteristic changing means is other than when the air pressure is suddenly reduced,
The control characteristic is changed only at a predetermined timing. According to such a configuration, since the control characteristic is not constantly changed, it is less likely that the driver feels uncomfortable due to the change of the control characteristic during traveling.

According to another preferred aspect of the present invention, the predetermined timing is when the engine is started, or
It is at a stop. In these cases, even if the control characteristic is changed, the driver does not feel uncomfortable.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will now be described in detail with reference to the drawings. First, the configuration of the first vehicle control device according to the embodiment of the present invention will be described. FIG. 1 is a block diagram showing a schematic configuration of a vehicle in which the vehicle control device 1 of the present embodiment is mounted. The vehicle control device 1 of the present embodiment detects the air pressure of the wheels (tires) 2,
The vehicle control device is capable of issuing an alarm when the air pressure deviates from an appropriate range and correcting the control characteristic of the vehicle according to the change of the air pressure.

As shown in FIG. 1, the vehicle control device 1 includes a detection device 4 attached to each wheel 2 of the vehicle and a processing device 6 arranged on the vehicle body side. The vehicle of the present embodiment has an anti-lock brake system (ABS),
Vehicle stability control (DSC: Dynamic Stability) with functions such as traction control system (TRC)
Control) device. In the vehicle of this embodiment, the gear ratio can be changed (VGR: Variable Gear Rati
o) Electric power steering equipped with a mechanism (EPS: Elec
tric power steering) device 7. further,
The vehicle of the present embodiment is equipped with a suspension device that can change the vibration characteristics by changing the hardness of the damper and change the vehicle height by changing the length of the damper.

The detection device 4 is mounted near the air valve of each wheel 2 and detects the pressure and temperature of the air inside each wheel (inside the tire) and processes the detection result as an air pressure signal on the vehicle body side. It is configured to send to the device 6.

As shown in FIG. 2, the detection device 4 includes a pressure sensor 8 for detecting the air pressure inside each wheel (tire) and a temperature sensor 10 for detecting the temperature of the air inside the wheel (tire). , An acceleration sensor 12 for detecting an acceleration applied to the wheel 2, and a memory 14 storing a tire identification ID.
Is equipped with. The detection device 4 further includes a transmission / reception CPU 16 that generates and transmits an air pressure signal including the detection values of the sensors 8, 10 and 12 and the tire identification ID in response to a request from the processing device 6 side. A transceiver 18 for transmitting and receiving is provided. The detection device 4 is configured to be operated by a built-in battery (not shown).

In this embodiment, the air pressure signal is, as shown in FIG. 3, a tire identification ID, an in-wheel air pressure signal, an in-wheel air temperature signal, an acceleration signal, an abnormal decrease code, a battery voltage signal and a failure code. Are transmitted in order from the detection device 4 to the processing device 6 side.

Tire identification ID included in the air pressure signal
Is a code used to identify that the air pressure signal is a signal from a wheel attached to the host vehicle, and is different for each processing device 4. This tire identification ID is collated with the tire identification ID registered on the processing device 6 side after being transmitted from the detection device 4. Further, the acceleration signal indicates the acceleration obtained by adding the acceleration due to the vertical movement of the wheel to the acceleration in the circumferential direction due to the rotation of the wheel. The abnormally low code is a code for notifying that the air pressure inside the wheels has dropped rapidly. Furthermore, the battery voltage signal and the failure code are signals used to notify the processing device 6 of the voltage of the built-in battery of the detection device 4 and the operating state of the detection device 4, respectively.

As shown in FIG. 1, a dedicated antenna 20 for receiving the air pressure signal transmitted from each detection device 4 is arranged at a position near each wheel 2. The pneumatic signal received by each antenna 20 is transmitted to the processing device 4.

The processing device 6 includes an air pressure alarm CPU 22 and
ABS / TRC / DSC control CPU 24 and EPS /
CPU 26 for VGR control and CP for suspension control
A U28, a general control CPU 30, and a storage unit 32 are provided.

When the air pressure of the wheel calculated based on the air pressure signal transmitted from any one of the detection devices 4 deviates from the appropriate range, the air pressure warning CPU 22 determines that
Pneumatic warning light 3 located in the instrument panel
4 is turned on to notify the occupant that the air pressure of any of the wheels is abnormal. Since the proper range of the air pressure is related to the air temperature in the wheel, the in-wheel air temperature included in the air pressure signal is taken into consideration when determining whether or not it is the proper range.

ABS / TRC / DSC control CPU 24
Is based on various information from the steering angle sensor, throttle opening sensor, wheel speed sensor, yaw rate sensor, etc.
In-vehicle vehicle stability control (DSC: Dynamic Stability Co
The control characteristics of the devices are determined, and the operation of these devices is controlled based on the control characteristics.

Similarly, the EPS / VGR control CPU 26
Determines the control characteristics such as the change of the assist amount of the electric power steering (Electric Power Steering) device, the change of the gear ratio and the timing of these changes based on the running state and driving state of the vehicle. On the basis of,
It is configured to control the operation of the electric power steering.

Further, the suspension control CPU 28
Determines the control characteristics such as the vibration characteristic control by changing the hardness of the suspension damper and the vehicle height control by changing the damper length based on the running state of the vehicle, and based on this control characteristic, the suspension device It is configured to control actuation.

Further, the total control CPU 30 has control characteristics necessary for correcting changes in the running characteristics of the vehicle due to changes in the air pressure of the wheels, such as changes in grip force, phase delay during steering, and changes in vehicle height. The change amount of is calculated. Specifically, when the air pressure of one of the front wheels has decreased by a certain amount, changes in the steering state such as phase delay during steering due to this decrease in air pressure are corrected, and the steering state is maintained when the air pressure is not reduced. In order to do so, the control characteristics of what control should be changed and how much is calculated. Similarly, correct the change in tire grip force on the road surface due to this decrease in air pressure,
In order to maintain the traveling state when the air pressure is not reduced, it is calculated which control characteristic should be changed and how much. The control characteristic change amount calculated based on such calculation is sent to the ABS / TRC / DSC control CPU 24, the EPS / VGR control CPU 26, and the suspension control CPU 28, which perform the respective controls. Is changed. Further, in this embodiment, the total control CPU
The reference numeral 30 suppresses or prohibits the change of the control characteristic of the EPS / VGR device when the air pressure of any of the wheels is larger than a predetermined value and falls from the appropriate range.

The storage means 32 stores the tire identification ID of the tire mounted on the host vehicle, data necessary for issuing an air pressure warning such as the proper air pressure of the mounted tire. Further, the storage means 32 stores data necessary for calculating the amount of change in the control characteristic that corrects the change in the traveling characteristic due to the change in air pressure, data necessary for calculating the condition for suppressing this change, and the like. Various data of are stored.

Next, the operation of the vehicle control device of this embodiment will be described. The tire identification ID of the detection device 4 attached to each wheel is stored in the storage means 32 of the processing device 6 when the vehicle is completed or when the tire is replaced. In the present embodiment, since the dedicated antenna 20 is arranged for each wheel 2, by causing each antenna 20 to receive the air pressure signal from each detection device 4, the wheel at which position has which tire identification ID. Can be registered.

During use of the vehicle, a pneumatic signal is sent from the detection device 4 to the processing device 6 in response to a request from the processing device 6 side. Based on this air pressure signal, the air pressure alarm CP
U22 determines whether the air pressure of each wheel is within the proper range stored in the storage means 32, and when it is out of the proper range, the air pressure warning lamp 34 is turned on.
When the vehicle is equipped with a device having a display screen such as a navigation device, the display shown in FIG. 4 is displayed on the screen, and the air pressure of which wheel is insufficient (or excessive). Yes, each wheel (front left wheel: F
L, right front wheel: FR, left rear wheel: RL, right rear wheel: RR) may be configured to notify the relationship between the air pressure and the proper air pressure zone. Furthermore, the dedicated wristwatch may be configured to display the current air pressure of each wheel and the proper air pressure on the display unit (FIG. 5).

Further, the total control CPU 30 calculates the change amount of each control characteristic of the vehicle necessary for correcting the change of the running characteristic due to the deviation of the wheel air pressure from the proper range, and this change amount is calculated. To the CPUs 24, 26 and 28 to change the control characteristics.

In this embodiment, ABS / TRC / DSC
Drift-out is avoided by the control CPU 24, etc.
Understeer control, which is control for suppressing, and oversteer control, which is control for avoiding / suppressing spin and the like, are performed. This understeer control controls the front inside wheel (the front inside wheel) or the rear inside wheel (the rear inside wheel) when the deviation between the control target yaw rate and the actual yaw rate is larger than the intervention threshold. Control is performed to add power. Further, in the oversteer control, when the deviation between the control target yaw rate and the actual yaw rate is smaller than the intervention threshold value, control is performed to apply a braking force to the front wheel on the outside of the turn (front wheel outside the turn).

In such control, basically, the control amount (braking amount) is set on the assumption that the air pressure of the wheel to be controlled (braking target) is within an appropriate range. However, when the air pressure of the target wheel deviates from the proper range, the desired effect cannot be obtained by performing the same control as when the air pressure is in the proper range. For example, in oversteer control, when the braking force is applied to the front wheel on the outside of the turn (the front wheel outside the turn), if the air pressure of this front wheel outside the turn is lower than the proper range, it is assumed that the air pressure is within the proper range. Even if the braking force is applied based on the control amount set to, the front wheel outside the turning that cannot exert sufficient grip force due to the decrease in air pressure cannot exert the predetermined braking force on the road surface, and as a result, The desired oversteer control will not be performed.

Therefore, in order to obtain the braking force necessary for oversteer control even when the air pressure is lower than the proper range, the control amount is based on the deviation from the proper range or the difference from the optimum air pressure. Is changed. In the present embodiment, the total control CPU 28 calculates the amount of change in the control characteristics based on the in-wheel air pressure, and the calculated result is
It is sent to the ABS / TRC / DSC control CPU 24 for control, and control is performed in consideration of the amount of change.

Further, when the air pressure of the steered wheels is lowered, the steering wheel operation becomes heavy and a phase delay occurs at the time of steering. Therefore, in the present embodiment, the general control CPU 30 operates the steering wheel based on the in-wheel air pressure during steering. The amount of change in control of the EPS device required to compensate for the characteristic change is calculated, and the result of this calculation is sent to the EPS / VGR CPU 24 that performs control, and the EPS device is controlled in consideration of the amount of change. Basically, the control content is changed such that the assist amount of the EPS device is large, the assist intervention timing is early, and the gear ratio is large.

At this time, basically, the control content of the EPS is changed so that the assist by the EPS device becomes larger as the air pressure inside the wheel becomes lower. For example, the EPS device is controlled based on I calculated from Ta + T′b (T is the magnitude of torque for twisting the steering shaft, T ′ is the speed at which the steering shaft is twisted, and a and b are coefficients). Sometimes, the coefficient b is increased to increase the EPS
The control content is changed so as to enhance the convergence property of the device.

Further, the control content of the EPS is changed so that the assist by the EPS device is reduced even when the air pressure of the rear wheels is relatively low with respect to the front wheels. This is to suppress the spin tendency due to the relatively high air pressure of the rear wheels.

Further, it is preferable to change the control characteristic of the EPS device so that the steering feeling in the left and right directions becomes the same when the difference in air pressure between the left and right wheels is a predetermined value or more. Since the gripping force of the outer wheels has a great influence on the vehicle turning, the change in the steering feeling due to the decrease in the air pressure differs depending on whether the wheel whose air pressure has dropped is the turning inner wheel or the outer wheel. That is, steering feeling is different between right turn and left turn. In order to prevent such a difference in steering feeling, the control characteristic of the power steering device is changed as described above.

Further, it is preferable that the control content of the EPS is changed so that the assist by the EPS device is reduced when the air pressure is rapidly reduced due to puncture or the like. This is to prevent a sudden movement of the vehicle due to the panic handle at the time of puncture.

It is preferable that the control characteristics of the EPS device be changed only when the engine is started or when the vehicle is stopped, except when the air pressure is suddenly reduced. Since the control characteristic is not constantly changed, the driver does not feel uncomfortable due to the change of the control characteristic during traveling.

In this embodiment, the vehicle height decreases when the air pressure of the wheels becomes low. Therefore, in this embodiment, the total control CP
Based on the air pressure in the wheels, U30 calculates the amount of change in the control amount of the suspension that corrects the decrease in air pressure, and the calculated result is the CP for suspension that controls.
The suspension device is sent to U28 to control the suspension device in consideration of the amount of change, and the vehicle is maintained horizontally at a predetermined vehicle height.

Further, when the air pressure of the wheel becomes high, the vibration characteristics change and the riding comfort deteriorates. Therefore, in this embodiment,
The total control CPU 30 calculates the amount of change in the suspension control amount that corrects the air pressure that is too high, based on the in-wheel air pressure of each wheel, and sends the result of this calculation to the suspension CPU 28 that controls the suspension amount. Is performed to maintain the vibration characteristics of the vehicle in an appropriate state.

Next, a vehicle controller according to the second embodiment of the present invention will be described. The vehicle control device of the present embodiment has basically the same configuration as the vehicle control device of the first embodiment. The difference from the vehicle control device of the first embodiment is that when the air pressure of the wheels becomes smaller than a predetermined value, the EPS
The point is that control is performed to suppress assist by the device. The difference will be described below.

In the present embodiment, the integrated control CPU suppresses the change of the control characteristics of the EPS device and fills the wheels with air to the driver when the air pressure of the wheels is larger than a predetermined value and falls from the appropriate range. Urge. That is, the correction for improving the deterioration of the traveling characteristics due to the decrease in the air pressure is suppressed or prohibited to make it difficult to drive, and the wheels are urged to be filled with air. Hereinafter, these processes performed by the general control CPU will be described with reference to the flowcharts of FIGS. 6A and 6B.

When the process starts, first, step S
1 determines whether DSC / ABS is operating, and Y
If ES, go to step S2, DSC / ABS
The flag F indicating the operation of is set to 1. Further, in step S3, the detection device 4 is instructed to increase the transmission rate of the pneumatic signal, and then the process proceeds to step S4.
This is because when the DSC / ABS is operating, it is necessary to frequently receive air pressure signals indicating the air pressure, acceleration, etc. of the wheels in order to precisely control these operations.

NO in step S1, that is, DSC / AB
When it is determined that S is not operating, step S
5, it is determined whether the flag F indicating the operation of the DSC / ABS is 1 or not.
If so, the flag F is reset in step S6, and the process proceeds to step S4.

In step S4, the air pressure in the wheel, the air temperature, and the information indicating the wheel acceleration included in the air pressure signal from the detection device 4 are input. Furthermore, step S
In step 7, the air pressure and the air temperature are collated with the data regarding the proper range of the tire pressure in the storage means to determine whether or not the current wheel air pressure is within the proper range.
If NO in step S7, the flow proceeds to step S8, and it is determined whether the air pressure has dropped by a predetermined value or more, that is, whether the air pressure has deviated significantly below the appropriate range.
If NO in step S8, that is, if it is in the "abnormal" region of the graph of FIG. 7, for example, the process proceeds to step S9, and the change amount of the control characteristic is calculated so as to compensate the decrease in the air pressure of the wheels.

When the air pressure of the steered wheels decreases, the steering wheel operation becomes heavy and a phase delay occurs at the time of steering. Therefore, the total control CPU 30 needs to compensate for these characteristic changes at the time of steering based on the in-wheel air pressure. The change amount of the control characteristic of the EPS device is calculated.

Then, the process proceeds to step S10, and the calculation result is used as a CP for EPS / VGR for controlling the EPS device.
Send to U26.

If YES in step S8, that is, if the air pressure is below the "abnormal" region in the graph of FIG. 7,
In step S11, it is determined whether the air pressure of the wheels is in a dangerous range where traveling is dangerous. Step S11
NO, that is, when the air pressure of any of the wheels is in a considerably low state but is in an "abnormal" region where traveling is not dangerous, the process proceeds to step S12, and it is determined whether or not the vehicle is stopped.

If YES in step S12, the flow advances to step S13 to change the control characteristic of the EPS device so as to decrease the assist amount, delay the decrease timing, and decrease the gear ratio of the VGR mechanism. By performing the control based on the changed control characteristic, the steering wheel becomes heavy and the reaction of the vehicle to the steering wheel operation becomes slow.
It should be noted that the control characteristic change in step S13 may be any change as long as it is a change in the direction of suppressing the operation of the EPS device that compensates for the decrease in the air pressure of the wheels.

If NO at step S12, the routine proceeds to step S14, where it is determined whether or not the vehicle is traveling at a low speed. If NO, then the routine proceeds to step S15 where it is determined whether or not the vehicle is traveling straight.

If NO in step S15, the vehicle is turning at medium or high speed, so the process proceeds to step S16, the same processing as step S9 is performed from the viewpoint of the safety and heavy visual field, and the control characteristic of the EPS device is adjusted so as to compensate the decrease in air pressure. Calculate the amount of change.

If YES in step S14 or YES in step S15, the process proceeds to step S17, where the control characteristics of the EPS device are changed so as to reduce the assist amount and reduce the gear ratio of the VGR mechanism. The amount of change in step S17 is set smaller than the amount of change in step S13. It should be noted that the control characteristic change in step S13 may be any change as long as it is a change in the direction of suppressing the operation of the EPS device that compensates for the decrease in the air pressure of the wheels. Therefore, the operation of the EPS device that compensates for the decrease in the air pressure of the wheels may be prohibited.

If YES in step S11, that is, if the air pressure of any of the wheels is extremely low and traveling is dangerous, the process proceeds to step S18, in which it is determined whether the vehicle is running at low speed or is in a stopped state. If YES in step S18, the flow advances to step S19 to change the control characteristic of the EPS device so as to reduce the assist amount of the EPS device and reduce the gear ratio of the VGR mechanism, and to control the steering wheel to vibrate. Send the command to the EPS device. If NO in step S18, the process proceeds to step S20 to reduce the assist amount of the EPS device and reduce the gear ratio of the VGR mechanism.
The control characteristics of the S device are changed. Steps S19 and S2
The change amount at 0 is set smaller than the change amount at step S17. Further, the change of the control characteristics in steps S19 and S20 may be any change as long as it is a change in the direction of suppressing the operation of the EPS device that compensates for the decrease in the air pressure of the wheels. Therefore, the operation of the EPS device that compensates for the decrease in the air pressure of the wheels may be prohibited.

Next, in step S10, the calculation result is used as the CPU 2 for EPS / VGR for controlling the EPS device.
6, the process proceeds to step S21, and the EPS device is controlled based on the determined control characteristic.

In the present embodiment, when the control characteristics of the EPS device are changed in steps S9 and S16, basically, the assist of the EPS device is increased so that the lower the air pressure in the wheel, the greater the assistance of the EPS device. Change the control contents. For example, the EPS device is Ta + T '
b (T is the magnitude of the torque for twisting the steering shaft, T'is the speed at which the steering shaft is twisted, a
When b and b are controlled based on I calculated from the coefficient, the coefficient b is increased and the control content is changed so as to enhance the convergence characteristic of the EPS device. Also, when the air pressure of the rear wheels is relatively low compared to the front wheels, the EP
The control content of the EPS device is changed so that the assistance by the S device is reduced. This is to suppress the spin tendency due to the relatively high air pressure of the rear wheels. Further, it is preferable to change the control characteristic of the EPS device so that the steering feeling in the left-right direction becomes the same when the difference in air pressure between the left and right wheels is equal to or greater than a predetermined value. Since the gripping force of the outer wheels has a great influence on the vehicle turning, the change in the steering feeling due to the decrease in the air pressure differs depending on whether the wheel whose air pressure has dropped is the turning inner wheel or the outer wheel. That is, steering feeling is different between right turn and left turn. In order to prevent such a difference in steering feeling, the control characteristic of the power steering device is changed as described above.

It is preferable that the control characteristics of the EPS device be changed only when the engine is started or when the vehicle is stopped, except when the air pressure is suddenly reduced. Since the control characteristic is not constantly changed, the driver does not feel uncomfortable due to the change of the control characteristic during traveling.

Further, it is preferable that the control content of the EPS is changed so that the assist by the EPS device is reduced when the air pressure is rapidly reduced due to a flat tire or the like. This is to prevent a sudden movement of the vehicle due to the panic handle at the time of puncture.

The above-mentioned change of the control characteristic is performed not only when the air pressure of any wheel deviates from the proper range but also when the air pressure of a plurality of wheels deviates from the proper range.

The present invention is not limited to the above embodiment, but various changes and modifications can be made within the scope of the matters described in the claims.

[0065]

According to the present invention, there is provided a vehicle control device for changing the steering characteristics of a vehicle so that the driver does not feel uncomfortable even if the air pressure of the wheels changes.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a vehicle equipped with a vehicle control device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a detection device.

FIG. 3 is a diagram showing a data format of a pneumatic signal.

FIG. 4 is an illustration of a wheel air pressure display.

FIG. 5 is a view showing a dedicated wristwatch displaying air pressure of wheels.

FIG. 6A is a flowchart showing a part of processing for determining control contents of the EPS device, which is executed by the comprehensive control CPU in the second embodiment of the present invention.

FIG. 6B is a flowchart showing the rest of the processing for determining the control content of the EPS device, which is executed by the overall control CPU in the second embodiment of the present invention.

FIG. 7 is a graph exemplifying an appropriate range of air pressure in a wheel.

[Explanation of symbols]

1: Vehicle control device 2: Wheel 4: Detection device 6: Processing device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B62D 101: 00 B62D 101: 00 113: 00 113: 00 127: 00 127: 00 137: 00 137: 00 F term (reference) 3D032 CC02 CC17 CC18 CC21 DA03 DA24 DA33 DA47 DA99 DB05 DB20 DC31 DD02 DD05 DE06 EB11 EC31 FF01 FF08 FF10 GG01

Claims (9)

[Claims] 1. An air pressure alarm system which detects the air pressure of each wheel and issues an alarm when the air pressure of any wheel deviates from a predetermined range, and a control of a power steering device of a vehicle according to the air pressure of the wheel. A vehicle control device comprising: a characteristic changing unit that changes a characteristic. 2. A vehicle control device comprising characteristic changing means for detecting the air pressure of each wheel and changing the control characteristic of the power steering device of the vehicle in accordance with the air pressure. 3. The vehicle control device according to claim 1, wherein the characteristic changing unit changes the control characteristic such that the assist by the power steering device increases as the air pressure decreases. 4. The vehicle control according to claim 1, wherein the characteristic changing unit changes the control characteristic such that the convergence characteristic of the power steering device is enhanced as the air pressure is lower. apparatus. 5. The characteristic changing means changes the control characteristic so that the assist by the power steering device becomes small when the air pressure of the rear wheels is relatively low. The vehicle control device described in the paragraph. 6. The characteristic changing means changes the control characteristic so that the steering feeling in the left-right direction becomes the same when the difference between the air pressures of the left and right wheels is equal to or more than a predetermined value. The vehicle control device according to claim 1. 7. The characteristic changing means changes the control characteristic so as to reduce the assist by the power steering device when the air pressure suddenly drops. The vehicle control device described. 8. The vehicle control device according to claim 1, wherein the characteristic changing unit changes the control characteristic only at a predetermined timing except when the air pressure is suddenly reduced. 9. The vehicle control device according to claim 8, wherein the predetermined timing is when the engine is started or when the vehicle is stopped.