JPH0443165A - Power steering device for vehicle - Google Patents

Abstract

PURPOSE:To operate a steering wheel always by a proper operating force independently of the tilt state of a vehicle by correcting the assisting force during the steering wheel operation by an assisting force correcting means according to the tilt state of a vehicle which is detected by a tilt state detecting means. CONSTITUTION:Steering angle sensors 12 and 13, torque sensors 14 and 15, car speed sensor 21, crank angle sensor 22 and a reverse switch 23 are installed, and the output signals of the first - fourth stroke sensors 24-27 which detect the stroke displacement in the vertical direction of a suspension device for front and rear wheels and detect the tilt state in the lateral and longitudinal directions of a car body are inputted into a CPU 32. When the tilt state in the lateral direction of the vehicle is detected, the steering power in the lateral direction of a steering wheel is made equal according to the tilt state, while if the tilt state in the longitudinal direction of the vehicle is detected, the assisting torque generated by a motor 16 is corrected so that the operating force of the steering wheel is made equal on an ascent and descent according to the tilt state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power steering device for a vehicle, and more particularly to a power steering device that corrects an assist force applied to a steering wheel operation.

(Conventional technology) In addition to the hydraulic type, there are other power steering devices for vehicles.
An electric power steering device is known in which an electric motor generates an assist force. For example, according to Japanese Patent Application Laid-Open No. 132465/1982, an electric power steering device that generates an assist force by an electric motor is disclosed. By controlling according to the steering angle speed detected by the steering angle sensor, a predetermined assist force is generated in accordance with the steering state.

(Problem to be Solved by the Invention) Incidentally, the power steering device as described above is designed to generate a predetermined assist force depending on the driving condition, but the operating force of the steering wheel depends on the driving condition or the driving condition. It depends on road surface conditions, etc., and is also greatly affected by the slope of the vehicle. For example, when the vehicle is tilted upward to the left on a slope and attempts to turn left. This requires a large amount of operating force, making the steering wheel difficult to operate, and when turning to the right, the front wheels are steered with less operating force, which results in the steering being too light and lacking a sense of control. In either case, the operability was reduced. Also, contrary to the above, when turning to the left or right when the slope is downward to the left, the steering wheel operation may be too heavy, or conversely too light, reducing operability. It had become.

On the other hand, if the vehicle is tilted in the longitudinal direction, for example, when going uphill, the center of gravity of the vehicle will be closer to the rear, resulting in the steering wheel being too light and lacking in operational feel, or vice versa. , When going downhill, the center of gravity of the vehicle is closer to the front, making it harder to operate the steering wheel, and in either case, the operability is reduced.

As described above, the operating force of the steering wheel changes significantly depending on the inclination state of the vehicle in the left-right direction and the front-rear direction, resulting in a decrease in operability.

SUMMARY OF THE INVENTION Therefore, the present invention provides a power steering device for a vehicle that generates an assisting force so that the steering wheel can always be operated with an appropriate operating force regardless of the vehicle's tilted state in the left-right direction and the front-back direction. The purpose is to improve the operability of the handle in a tilted state.

(Means for Solving the Problems) In order to solve the above problems, the present invention is characterized by the following configuration.

First, the invention according to the first claim of the present application (hereinafter referred to as the "first invention") is a power steering system for a vehicle equipped with an assist force generating means for generating an assist force for steering operation when the steering wheel is operated. The present invention is characterized in that it is provided with a tilt state detection means for detecting the tilt state, and an assist force correction means for correcting the assist force by controlling the operation of the assist force generation means based on an output signal from the detection means. .

Further, the invention according to the second claim of the present application (hereinafter referred to as the second invention) is a power steering device for a vehicle that is equipped with an assist force generating means similarly to the first invention. By controlling the operation of the assist force generating means based on the tilt state detection means to detect and the output signal from the detection means, the assist force is corrected so that the operating force in the left and right direction when operating the steering wheel is equalized. The present invention is characterized in that it is provided with an assist force correction means.

Furthermore, the invention according to the third claim of the present application (hereinafter referred to as the third invention) is a power steering device for a vehicle equipped with an assist force generating means for generating an assist force similarly to the first and second inventions. The steering wheel can be operated on uphill and downhill slopes by controlling the operation of the assist force generating means based on a tilt state detection means for detecting the tilt state of the vehicle in the longitudinal direction and an output signal from the detection means. The present invention is characterized by providing an assist force correction means for correcting the assist force so that the forces are equal.

(Function) According to the first aspect of the invention, the assist force correcting means, depending on the tilting state of the vehicle detected by the tilting state detecting means,
The assist force applied when operating the steering wheel is corrected, so that the steering wheel can always be operated with the appropriate operating force regardless of the vehicle's tilted state. This prevents the device from becoming heavy and improves its operability.

Further, according to the second invention, the assist force correction means assists so that the operating force in the left and right direction when operating the steering wheel is equalized according to the tilt state of the vehicle in the left and right direction detected by the tilt state detection means. The force is corrected, and as a result, the steering wheel can be operated with the appropriate operating force at all times, regardless of the vehicle's lateral tilt.
This will improve its operability.

Furthermore, according to the third invention, the assist force correction means adjusts the operating force of the steering wheel to be equal on an uphill slope and a downhill slope, depending on the slope state of the vehicle in the longitudinal direction detected by the slope state detection means. The assist force is corrected, and as a result, the steering wheel can be operated with the appropriate operating force at all times regardless of the vehicle's longitudinal tilt state, that is, whether it is uphill or downhill, improving operability. It will improve.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic configuration diagram of a power steering device according to the present invention, and the power steering device 1 includes a first steering shaft 3 to which a steering wheel 2 is attached at one end, and a lower end of the first steering shaft 3. a second steering shaft 5 connected to a lower end of the second steering shaft 5 via a universal joint 4; a third steering shaft 7 connected to a lower end of the second steering shaft 5 via a universal joint 6; an output shaft 8 connected to the output shaft 8 via a torsion bar (not shown), a pinion 9 formed at the lower end of the output shaft 8, and a steering rod 11 formed with a rack 10 that meshes with the pinion 9. Left and right front wheels (not shown) are connected to both ends of the steering rod 11 via tie rods and knuckle arms.

The third steering shaft 7 has a conventionally known configuration for electrically detecting the rotation angle of the steering shaft 7, in other words, the steering angle of the left and right front wheels using a sliding resistance transducer. A pair of first and second steering angle sensors 12 and 13 are provided, and the third steering shaft 7 below the steering angle sensors 12 and 13 receives an operating force (operating torque) applied from the steering wheel 2. A pair of first and second torque sensors 14, 15 are provided, each of which has a conventionally well-known configuration for electrically detecting the torque of the steering wheel using a sliding resistance transducer. 2, the amount of elastic deformation of the torsion bar connecting the third steering shaft 7 and the output shaft 8 is electrically detected by a sliding resistance transducer.

Further, a DC motor 16 (hereinafter simply referred to as a motor) and an electromagnetic clutch 17 are provided, which apply assist force to the output shaft 8 when the steering wheel 2 is operated.
For example, it is attached to a steering column (not shown) that rotatably supports the third steering shaft 7 and the output shaft 8. Further, a disc member 18 is integrally attached to the output shaft 8, and a gear 19 that meshes with a gear (not shown) formed on the outer peripheral edge of the upper surface of the disc member 18 is connected to the motor 16. It is designed to be rotationally driven via an electromagnetic clutch 17. Therefore, by rotating the motor 16 forward and backward with the electromagnetic clutch 17 connected, the gear 19 rotates the disk member 18 that is integrated with the output shaft 8.
It is now possible to apply an assist force to rotate the wheel in the right or left turning direction.

Next, the control system of the power steering device 1 will be explained.

As shown in the second rM, a control unit 20 having a built-in microcomputer is provided, and the first and second steering angle sensors serve as sensors and switches for inputting various signals to the control unit 20. 12, 13 and first and second torque sensors 14,
15, at least a vehicle speed sensor 21, a crank angle sensor 22, a reverse switch 23, and first to fourth
Stroke sensors 24-27 are provided.

The vehicle speed sensor 21 is a sensor that electrically detects, for example, the rotational speed of an automatic transmission output shaft (that is, the rotational speed of a propeller shaft), but may also detect the rotational speed of a front wheel or a rear wheel.

The crank angle sensor 22 is provided in conjunction with the distributor or crankshaft of the engine, and electrically detects the rotational speed of the crankshaft.

Further, the reverse switch 23 is provided in the automatic transmission, and is turned on when the gear position is not changed to "reverse".
This is a switch that becomes N.

Furthermore, the first to fourth stroke sensors 24 to
Reference numeral 27 is provided with a suspension device for front and rear wheels, or between the suspension device and the vehicle body, and detects stroke displacement in the vertical direction of the front and rear wheels, and based on this detects the tilting state of the vehicle body in the left-right direction and the front-rear direction. This is to detect.

The reverse signal from the reverse switch 23 is input to the waveform shaping circuit 30 via the digital buffer 29, where it is converted into a pulse signal and input to the CPU 32. In addition, the generated voltage signal from the output side terminal 28 of the alternator is transferred to the digital buffer 2.
The pulse signal is inputted to the waveform shaping circuit 31 via the waveform shaping circuit 9, and is converted into a pulse signal by the waveform shaping circuit 31 and inputted to the CPU 32. Furthermore, the signal from the vehicle speed sensor 21 and the signal from the crank angle sensor 22 are input to the CPU 32 via a digital buffer 29.

On the other hand, signals from the first and second steering angle sensors 12.13 and signals from the first and second torque sensors 14.15,
Signals from the first to fourth stroke sensors 24 to 27 are sent to the A/D converter 3 via an analog buffer 33.
4, is converted into a digital signal by this A/D converter 34, and is input to the CPU 32.

Further, the CPU 32 connects to the ROM 35 via the bus.
ROM354: is connected to the motor 1
A control program to be described later for controlling the electromagnetic clutch 6 and the electromagnetic clutch 17 is stored in advance, and the RAM 36 is provided with various memories (registers, flag memories, soft counter memories, etc.) necessary for the arithmetic processing of the control.

Further, the battery 37 as a power source is connected to a constant voltage circuit 39 via an ignition switch 38, and the constant voltage circuit 39 supplies a predetermined constant voltage (for example,
5V) is supplied, and the output voltage of the output terminal of the battery 37 for detecting the voltage of the battery 37 is output from the A/D.
It is converted into a digital signal by the converter 34 and sent to the CPU 32.
It is now entered into

In addition, in order to control the direction and magnitude of the DC current supplied to the motor 16, the D/A converter receives a digital motor drive current control signal from the CPU 32 and converts it into D/A.
A converter 40 receives an analog control signal supplied from this D/A converter 40 and an analog current detection signal supplied from current detector 44, and generates a current in the direction and magnitude supported by the control signal. PWM the motor drive current so that
A current control port 841 that performs feedback control using a method, a driver 42 that receives and amplifies an analog command signal supplied from this current control circuit 41, and a battery 3.
A power circuit 43 is connected to the output terminal of 7 via a power supply line 45, and is also connected to the motor 16 and supplies the motor 16 with a motor drive current according to an amplified command signal supplied from the driver 42. and is provided.

Note that the current detector 44 is interposed in the ground line from the power circuit 43 to the ground, detects the direction and magnitude of the motor drive current, and sends the analog detection signal to the current control circuit 41.
and the A/D converter 34.

Furthermore, an electromagnetic clutch 17 incorporated in the motor 16
In order to control ON10FF and the magnitude of the excitation current supplied to the electromagnetic clutch, the CPU 32 receives and receives control signals, and is connected to the input line 50 of the constant voltage circuit 39 via the power supply line 46, and is connected to the electromagnetic clutch. Current control circuit 47 connected to the input terminal of solenoid 17a of No. 17
A drive circuit 48 receives and receives control signals from the CPU 32 and is connected to the output terminal of the solenoid 17a to turn on or off the excitation current according to the control signal, and a drive circuit 48 that monitors the excitation current of the solenoid 17a and outputs a monitor signal. C
A monitor circuit 49 that supplies data to the PU 32 is provided.

Note that when the constant voltage circuit 39 becomes unable to output a predetermined constant voltage due to a drop in the voltage of the battery 37, etc., the C
Since the operation of the PU 32 is no longer guaranteed, in this case, the constant voltage circuit 39 outputs the current control circuit 47 heliset signal RST, the excitation current is switched off, and the electromagnetic clutch 17 is turned off.

Here, the control operations executed by the control program stored in the ROM 35 of the control unit 20 will be explained based on the flowcharts shown in FIGS. 3 to 5.

As shown in FIG. 3, when control is started in response to turning on the ignition switch 38, first, predetermined initial settings are executed (step Sl), and then the first and second torque sensors 14, A steady deviation calculation processing routine (shown in FIG. 4) for calculating the steady deviation of the motor 16 and the electromagnetic clutch 17 is executed (step 5to).
A control routine (shown in FIG. 5) is executed (step 520), and thereafter this control routine will be executed repeatedly.

Further, as shown in FIG. 4, when the steady-state deviation calculation processing routine is started, the vehicle speed signal V from the vehicle speed sensor 21, the steering angle signal θh from the first steering angle sensor 12, and the steering angle signal θh from the first torque sensor 14 are detected. The torque signal Tm is read (step 5st). In this case, the vehicle speed v=0 at the 0th order where reading is performed multiple times in a predetermined minute time,
If the absolute value of the torque Tm is less than or equal to the predetermined small constant 01 (step S12, step 5ts), the steering angular velocity gh is calculated (step 514), and the steering angular velocity g
When h=o (step 5ts), the first and second
The torque signals Tm and Ts from the torque sensors 14 and 15 are read (step 516), and then the steady-state deviation ΔTd between the detected values of both the torque sensors 14 and 15 is calculated as ΔT.
Calculated by d - T m - T s (Step 517) In this way, when the vehicle is substantially stopped and not being steered, the steady state reserve difference ΔTd is calculated by reading the torque signals Tm and Ts. As a result, the variation in accuracy and the difference in degree of deterioration between the first and second torque sensors 14 and 15 are determined as the steady state reserve difference ΔTd.

Next, the control operations for the motor 16 and the electromagnetic clutch 17 that are executed after the above-mentioned steady-state deviation calculation processing routine will be explained based on the flowchart shown in FIG.

First, in step S21, it is determined whether the absolute value of the steady-state deviation ΔTd obtained in the steady-state deviation calculation processing routine described above is greater than or equal to a predetermined constant 02. If YES, in step S22, the first and second torque sensors 14,15
It is determined that at least one of the electromagnetic clutches 17
A clutch OFF control signal for cutting off the motor 16 is output to the drive circuit 48, and a motor stop signal for stopping the motor 16 is output to the D/A converter 40, as well as a drive circuit for an alarm and an alarm buzzer (not shown). An alarm output signal is output to.

On the other hand, when the determination in step S21 is No, in step S23 the memory data of the steady reserve difference ΔTd stored in the memory of the RAM 36 is updated with the current data, and in step S24, the vehicle speed signal V , the steering angle signal θh, and the torque signal Tm are read. Next, in step S25, it is determined that the vehicle speed V is equal to or higher than a predetermined value C3, which is not too large, and in step S2
When the absolute value of the steering angle θh is determined to be equal to or greater than the small predetermined value 04 in step S27, and furthermore, the absolute value of the torque Tm is determined to be equal to or greater than the predetermined value 05 in step S27, that is, when the vehicle is in a running state. If the steering wheel is present and the vehicle is being steered, the torques Tm and Ts are read in step 52g, and then, in step S29, the torque sensor failure determination is made if l (Tm~Ts)-ΔTdl≧C6 (however, C
6 is a predetermined setting value).

If YES, it is determined that the torque sensor has failed and the process moves to step S22.

That is, to give a supplementary explanation, the first. second torque sensor 14,
15 is operating normally, the torques Tm and Ts read in step SZS are used (Tm-Ts).
is substantially equal to the steady-state deviation ΔTd, so in that case, l(Tm-Ts)-ΔTd l =O. However, when one of the torque sensors 14, 15 fails, (Tm-Ts) becomes significantly larger or smaller, so l(Tm-Ts)-ΔTdl≧C6.

Then, when the determination in step 329 is No, that is, when it is determined that the first and second torque sensors 14.15 are normal, steps SSO to SSS are executed, and the drive motor 16 and clutch 17 is controlled.

First, in step SSO, the vehicle speed signal V, steering angle signal θh, and torque signal Tm are read, and then in step sil, 1×Tm is calculated as the basic assist torque. This basic assist torque lXTm is preset to the characteristics shown in Fig. 6 using vehicle speed V and detected torque Tm as parameters, K1 is a function of vehicle speed V and torque Tm, and the number Kl(V, Tm ) is stored in the ROM 35 in the form of a map, for example, and the basic assist torque XTm is calculated using the value read from the map. Here, as shown in FIG. 6, the basic assist torque KI XTm is set to decrease as the vehicle speed (2) increases, and to increase as the torque Tm increases.

Next, in step SS2, the steering angular velocity gh is calculated using the current steering angle θh and the previous steering angle θh, and 2X4h is calculated as the steering angular velocity correction term based on the steering angular velocity gh. This correction term, 2 ) is stored in ROM3 in the form of a map, for example.
5, 2X4h is calculated for the steering angular velocity correction term using the value read from the map. Note that the correction term 2X4h is intended to correct the assist torque AT to the decreasing side to ensure steering stability especially when the steering angular velocity +h is large.

Subsequently, in step SSS, the current steering angular velocity g
The steering angle acceleration θh is calculated using h and the previous steering angle velocity 6h, and the steering angle acceleration correction term K is calculated.

×δh is calculated. In this correction term, Xθh is set to a characteristic as shown in FIG. 8 using the steering angle acceleration θh as a parameter, and KS is a predetermined constant. Note that in this correction term, Xθh is intended to correct a response delay due to the inertia of the rotor of the motor 16 at the start of steering.

Further, in step SS4, 4Xθh is calculated as a steering angle correction term using the steering angle θh given by the steering angle signal θh.

This correction term, 4×θh, is set to a characteristic as shown in FIG. 9 using the steering angle θh as a parameter, and is calculated using a predetermined calculation formula. Note that 4×θh is added to this correction term to add a return torque to return the steering wheel 2 to the neutral position, and as shown in FIG. 9, hunting is prevented by providing a dead zone. There is.

Further, in step S35, the tilt angle αX of the vehicle in the left-right direction is calculated based on the signals α from the first to fourth stroke sensors 24 to 27, and XαX is calculated as the tilt correction term. In this correction term, 5xαX is set to a characteristic as shown in FIG. 10 using the horizontal inclination angle αX as a parameter, and 5 is a predetermined constant.

However, if the vehicle is tilted upward to the left and attempts to turn to the left, K5 is set to a positive value and the assist torque is increased, and if the vehicle attempts to turn to the right, K5 is set to a negative value, and the assist torque is reduced. Additionally, if the vehicle is tilted upward to the right and attempts to turn to the right, K5 will be set to a positive value, and if the vehicle attempts to turn to the left, K5 will be set to a negative value. be done. Note that in this correction term, XαX increases or decreases the assist torque in accordance with the tilting state when the vehicle is tilted in the left-right direction.

Furthermore, in step SS6, the inclination angle αy of the vehicle in the longitudinal direction is calculated based on the signals α from the first to fourth stroke sensors 24 to 27, and 6×αy is calculated as the inclination correction term. Ru. This correction term is 6×α
y is set to a characteristic as shown in FIG. 11 using the inclination angle αy in the longitudinal direction as a parameter, and 6 is a predetermined constant.

However, when the vehicle is tilted downward (for example, while driving downhill), K6 is set to the glass value, the assist torque is increased, and the vehicle is tilted downward! ! (For example, while traveling uphill), K6 is set to a negative value and the assist torque is reduced. Note that the correction term 6Xαy is used to increase or decrease the assist torque in accordance with the tilted state when the vehicle is tilted in the longitudinal direction.

Then, in step SS, the basic assist torque KI
XTm, five correction terms Kz X b h, and 3
The assist torque AT that assists the steering of the steering wheel 2 by the motor 16 using θh, 4 Xθh, 5 Xαx, and 6 Xαy is AT=lXT.
m- to 2x4h+ 3 xθh- to 4xθh+, Xa
It is calculated by the calculation formula of 6×αy for X0, and step 33
8, a motor drive current control signal corresponding to the assist torque AT calculated by the above calculation formula is output to the D/A converter 40, and a crank angle signal for switching the clutch 17 to the connected state is output to the drive circuit 48. will be output to .

In this way, the first to fourth stroke sensors 24 to 2
7, when a tilted state of the vehicle, that is, a tilted state of the vehicle in the left-right direction is detected, the motor 1 is adjusted accordingly so that the operating force in the left-right direction of the steering wheel is equalized.
The assist torque AT generated by 6 is corrected, and as a result, the steering wheel can always be operated with an appropriate operating force regardless of the vehicle's left/right tilted state, and the steering wheel may be operated too lightly. Or conversely, it is prevented from becoming heavy, and the operability can be improved.

Further, when each of the stroke sensors 24 to 27 detects a tilt state of the vehicle in the longitudinal direction, the motor 16 generates a force corresponding to the tilt so that the operating force of the steering wheel is equal on an uphill slope and a downhill slope. As a result, the steering wheel can always be operated with an appropriate operating force regardless of whether the vehicle is tilted in the longitudinal direction, that is, whether it is uphill or downhill. This will improve your sexuality.

Although omitted in the above explanation, in the steady-state deviation calculation processing routine shown in FIG. Similarly, the steady-state deviation is determined, and the failure of both steering angle sensors 14 and 15 is determined in the same manner as in step S21 and step S29. When these steering angle sensors 14 and 15 are in failure, the process moves to step S2□. It is also possible to configure as follows, and furthermore, it is possible to set 4 in FIG. 9 as a function of vehicle speed 4 (V).

Furthermore, the crank angle sensor 22 is provided as a countermeasure against a failure of the vehicle speed sensor 21, and since there is roughly a certain correlation between the vehicle speed V and the engine rotation speed Ne, if the vehicle speed sensor 21 fails, The vehicle speed is estimated based on the crank angle signal, and when the reverse signal from the reverse switch 23 is turned on, control is performed to reduce the assist torque AT by a predetermined percentage. Furthermore, when the generated voltage of the alternator is below a predetermined value, the motor 16 and the electromagnetic clutch 17 are turned off.
Control is performed such that F.

(Effects of the Invention) As described above, according to the first invention, the assist force correction means applies the assist force to the operating force when operating the steering wheel, depending on the lean state of the vehicle detected by the lean state detection means. The force is corrected, and as a result, the steering wheel can always be operated with the appropriate operating force regardless of the tilting state of the vehicle, and the steering wheel is prevented from operating too lightly or becoming too heavy. As a result, its operability can be improved.

According to the second aspect of the invention, the assist force correction means equalizes the left and right operating force when operating the steering wheel, depending on the left and right tilt state of the vehicle detected by the tilt state detection means. The assist force will be corrected, allowing the driver to always operate the steering wheel with the appropriate operating force regardless of the vehicle's lateral tilt.
This will improve its operability.

Furthermore, according to the third invention, the assist force correction means adjusts the operating force of the steering wheel to be equal on an uphill slope and a downhill slope, depending on the slope state of the vehicle in the longitudinal direction detected by the slope state detection means. The assist force is corrected, and as a result, the steering wheel can be operated with the appropriate operating force at all times regardless of the vehicle's longitudinal tilt state, that is, whether it is uphill or downhill, improving operability. It will improve.

[Brief explanation of the drawing]

The drawings show an embodiment common to the first to third inventions, and FIG. 1 is a schematic configuration diagram of a power steering device for a vehicle according to the present embodiment, and FIG. 2 is an overall system diagram of a control system of the device. , Fig. 3 is a flowchart showing the basic control operation for the device, Fig. 4 is a flowchart showing the steady-state deviation calculation processing operation, Fig. 5 is a flowchart showing the control operation for the motor and clutch, and Fig. 6 is the basic control operation. Characteristic diagram of assist torque, Fig. 7 is a characteristic diagram of steering angular velocity correction term, Fig. 8 is a characteristic diagram of steering angle acceleration correction term, Fig. 9 is a characteristic diagram of steering angle correction term, and Figs. 10 and 11 respectively. FIG. 3 is a characteristic diagram of a tilt correction term. 1...Power steering device, 2...Handle (
steering wheel), 16... Assist force generation means (DC motor), 20... Assist force correction means (control unit), 24-27... Tilt state detection means (first to fourth stroke sensors) . Figure Figure

Claims (3)

[Claims] (1) In a power steering system for a vehicle that is equipped with an assist force generating means that generates an assist force in response to a steering wheel operation, the vehicle includes a tilt state detection means that detects a tilt state of the vehicle, and an output signal from the detection means. A power steering device for a vehicle, comprising: an assist force correcting means for correcting the assist force by controlling the operation of the assist force generating means. (2) In a power steering device for a vehicle equipped with an assist force generating means that generates an assist force in response to a steering wheel operation, a tilt state detecting means detects a tilt state of the vehicle in the left and right direction, and an output from the detecting means. The present invention is characterized by further comprising an assist force correction means for correcting the assist force so that the operating force in the left and right directions when operating the steering wheel is equal by controlling the operation of the assist force generating means based on the signal. Vehicle power steering device. (3) In a power steering device for a vehicle equipped with an assisting force generating means for generating an assisting force in response to a steering wheel operation, a tilting state detecting means detecting a tilting state of the vehicle in the longitudinal direction; assist force correction means for correcting the assist force so that the operating force of the steering wheel is equal on uphill and downhill slopes by controlling the operation of the assist force generation means based on the output signal of Characteristic vehicle power steering device.