JP2007253829A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device having a safety driving system capable of reducing the accident rate. <P>SOLUTION: In the power steering device, the steering speed of a steering member (not shown) is detected, the target number of rotation of a motor is determined based on the detected steering speed and the given vehicular speed, the motor M is drive-controlled at the predetermined target number of rotation, and the steering assist is performed by the hydraulic pressure generated by an oil pump interlocked with the motor M. The power steering device comprises an acquisition means 25 for acquiring information indicating the traveling state or the peripheral situation other than the vehicular speed, and a changing means 20 for changing the target number of rotation based on information acquired by the acquisition means 25. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power steering device that drives and controls an electric motor at a target rotational speed determined based on a steering speed and a vehicle speed, and assists steering by a hydraulic pressure generated by an oil pump linked to the electric motor.

  Recently, hydraulic power steering devices that supply hydraulic oil from an oil pump to a power cylinder coupled to a steering mechanism of a vehicle and generate a steering assist force from the power cylinder have become widespread. In such a power steering apparatus, in order to obtain the optimum steering assist force, the instruction rotational speed to the electric motor is determined according to the motor rotational speed map as shown in FIG. 4 which is determined by the steering speed and the vehicle speed (vehicle speed). ing.

In addition, vehicles are provided with various safe driving systems for reducing the burden of driving operations and for avoiding various dangers that occur during traveling.
For example, Patent Document 1 calculates a lateral movement amount predicted value after a predetermined time of a vehicle and a maximum lateral movement amount for preventing the vehicle from deviating from the travel lane, and calculates a lateral movement amount predicted value with respect to the maximum lateral movement amount. An electric power steering device that reduces the applied steering force in accordance with an increase in the ratio is disclosed.

Patent Document 2 discloses a power vehicle including a collision avoidance unit that corrects a steering angle according to a turning instruction in a collision avoidance direction based on an obstacle detection output by an obstacle detection sensor. .
Further, Patent Document 3 includes a steering gear ratio control unit that controls a steering gear ratio that is a transmission ratio of a steering rudder angle to a front wheel rudder angle. There is disclosed a vehicle steering control device that predicts a collision margin time that is a time during which a vehicle collides with an obstacle, and performs control to increase the steering gear ratio when the collision margin time at the start of steering is within a predetermined value.

Further, Patent Document 4 determines whether or not the approach of the object from behind and the steering to the left and right sides are possible based on the detection result of the surrounding state detection unit, and how the steering unit is operated based on the determination result. Regardless, a vehicle steering apparatus that forcibly operates a steering actuator is disclosed.
JP 11-99955 A JP 2002-225741 A JP 2003-165461 A JP 2004-30361 A

Since the hydraulic power steering device is a mechanism that supplies hydraulic oil from an oil pump to a power cylinder coupled to a steering mechanism and generates a steering assist force from the power cylinder, it is difficult to incorporate a safety device as described above. Up to now, the incorporation of safety devices has not been proposed.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a power steering apparatus including a safe driving system capable of reducing the accident occurrence rate.

  A power steering device according to a first aspect of the invention detects a steering speed of a steering member, determines a target rotational speed of an electric motor based on the detected steering speed and a given vehicle speed, and sets the target rotational speed at the determined target rotational speed. In a power steering device that drives and controls an electric motor and assists steering by hydraulic pressure generated by an oil pump that is linked to the electric motor, an acquisition unit that acquires information indicating a running state other than the speed of the vehicle or a surrounding situation; And changing means for changing the target rotational speed based on the information acquired by the acquiring means.

  The power steering apparatus according to a second aspect of the present invention further comprises means for determining whether or not a state or situation is required for sudden steering based on the information obtained by the obtaining means, and the means requires sudden steering. If it is determined that, the changing means is configured to increase the target rotational speed.

  In the power steering device according to a third aspect of the invention, the target rotational speed is recorded in a plurality of reference tables corresponding to the steering speed and the vehicle speed, and the changing means switches the reference table to change the target speed. It is configured to change the rotation speed.

  According to the power steering device of the first invention, the steering speed of the steering member is detected, the target rotational speed of the electric motor is determined based on the detected steering speed and the given vehicle speed, and the determined target rotational speed is determined. The electric motor is driven and controlled, the steering assist is performed by the hydraulic pressure generated by the oil pump linked to the electric motor, the acquisition unit acquires information indicating the running state other than the vehicle speed or the surrounding situation, and the changing unit is Since the target rotational speed is changed based on the information acquired by the acquisition means, it is possible to realize a power steering apparatus equipped with a safe driving system that can reduce the accident occurrence rate.

  According to the power steering device of the second invention, the determining means determines whether or not the state or the situation requires the sudden steering based on the information acquired by the acquiring means, and the determining means determines whether the rapid steering is performed. When it is determined that it is necessary, the changing means increases the target rotational speed, so that it is possible to realize a power steering apparatus equipped with a safe driving system capable of reducing the accident occurrence rate.

  According to the power steering apparatus of the third invention, the target rotational speed is recorded in a plurality of reference tables corresponding to the steering speed and the vehicle speed, and the changing means switches the reference table to change the target rotational speed. Since the number is changed, the target steering speed can be changed quickly, and a power steering device including a safe driving system that can reduce the accident occurrence rate can be realized.

The present invention will be described below with reference to the drawings showing embodiments.
FIG. 1 is an explanatory view schematically showing a main part configuration of an embodiment of a power steering apparatus according to the present invention. This power steering device assists steering in a steering mechanism 1 of a vehicle, and a steering shaft 3 is connected to a steering wheel 2. A pinion 4 is attached to the tip of the steering shaft 3, and the pinion 4 meshes with a rack shaft 5 that extends in the vehicle width direction. A front wheel tire 7 is attached to the rack shaft 5 via a tie rod 6 (only one of the tie rod 6 and the front wheel tire 7 is shown).

The rack shaft 5 is also connected with a piston 11 of a power cylinder 10, and the power cylinder 10 includes a pair of cylinder chambers 10 a and 10 b formed by the piston 11. A hydraulic control valve 13 is connected to the cylinder chambers 10a and 10b through oil supply paths 12a and 12b indicated by broken lines, respectively.
The hydraulic control valve 13 is connected in the middle of an oil circulation path 14 indicated by a broken line, and the hydraulic oil stored in the reservoir tank 15 is pumped out by the oil pump 16 and pumped out. After the hydraulic oil is discharged from the oil pump 16, it is configured to return to the reservoir tank 15 again.
When the oil pump 16 is driven by the electric motor M, the hydraulic oil circulates through the oil circulation path 14, and when it is not driven, the circulation of the hydraulic oil is stopped.

  The opening of the hydraulic control valve 13 changes according to the direction and magnitude of the torque applied to the steering shaft 3, thereby changing the supply state of hydraulic oil to the power cylinder 10. When hydraulic oil is supplied to any cylinder chamber of the power cylinder 10, the piston 11 moves in any direction along the vehicle width direction, thereby generating a steering force and moving the rack shaft 5. Assisted.

The vehicle speed sensor 18 detects the rotational speed of a rotor provided on a hub shaft (not shown) that rotates integrally with the front tire 7 and detects a magnetic metal piece fixed to the rotor. Alternatively, an optical sensor that optically detects holes provided in the rotor can be used. A vehicle speed signal V which is a detection signal of the vehicle speed sensor 18 is given to the electronic control unit ECU.
The steering shaft 3 is provided with a steering angle sensor 8 having a rotary encoder for detecting the steering angle of the steering wheel 2, and a pulse signal S of the rotary encoder is given to the electronic control unit ECU.

A hall sensor 17 for detecting the rotor position of the electric motor M is attached to the electric motor M, and a detection signal of the hall sensor 17 is given to the electronic control unit ECU.
The electronic control unit ECU determines the designated rotational speed based on the given pulse signal S and the vehicle speed signal V, and based on the deviation between the designated rotational speed and the rotational speed calculated from the detection signal of the hall sensor 17, the electric motor M The drive circuit 19 is feedback-controlled to drive the electric motor M, thereby driving the oil pump 16.

  In the power steering device having such a configuration, when the steering wheel 2 is operated and the rotational force is transmitted to the steering shaft 3, the pinion 4 at the tip thereof rotates, whereby the rack shaft 5 moves in the vehicle width direction. Move to. As a result, the amount of movement of the rack shaft 5 is transmitted to the tie rod 6, and the direction of the front tire 7 changes. The power cylinder 10 generates an auxiliary force to be applied to the rack shaft 5 when the rack shaft 5 moves in the vehicle width direction.

FIG. 2 is a block diagram illustrating a configuration example of the electronic control unit ECU, the drive circuit 19, the electric motor M, and the hall sensor 17 described above.
In the electronic control unit ECU, the steering speed calculation unit 24 is given a pulse (sequence) signal S from the steering angle sensor 8 having a rotary encoder, and the steering speed is calculated based on the number of given pulse signals S per predetermined time. The steering speed signal Vθ is calculated and given to the motor rotation speed map unit 20. Further, a vehicle speed signal V from the vehicle speed sensor 18 is given to the motor rotation speed map unit 20.

  The determination unit (acquisition unit, determination unit) 25 is provided with an information signal indicating a traveling state other than the speed of the vehicle and the surrounding situation from the outside, and whether or not rapid steering is necessary based on the given information. And an instruction signal corresponding to the determination result is given to the motor rotation speed map unit (changing means) 20. The information signal given to the determination unit 25 includes, for example, a night view signal indicating whether an obstacle is detected from the night view system (night safety driving support system), and an ABS (Anti-lock Brake System) is activated. This is an ABS signal or the like indicating whether or not. In addition, a traffic signal indicating whether or not the vehicle is located in a traffic jam section, which is generated by a car navigation device (not shown) based on a received VICS (Vehicle Information and Communication System) signal and vehicle position information, is also given. . Further, a winker operation signal from CAN 30 (Controller Area Network), a signal indicating that the vehicle is stopped, and the like are also given.

The motor rotation speed map unit 20 records a plurality of reference maps (motor rotation speed maps) that define the relationship among the steering speed, the vehicle speed, and the rotation speed of the electric motor M as shown in FIG. In response to the steering speed signal Vθ and the vehicle speed signal V, an instruction rotational speed to the electric motor M is output and provided to the deviation calculating unit 21. Moreover, the instruction | command rotation speed to the electric motor M is changed by switching a reference map according to the instruction | indication signal from the determination part 25. FIG.
In addition, if the rotation speed of the electric motor M is increased, the pressure of the hydraulic oil in the power cylinder 10 is increased, and naturally the steering assist force is increased.

The detection signal of the hall sensor 17 is given to the rotation number calculation unit 31, and the rotation number calculation unit 31 calculates the rotation number of the electric motor M based on the given detection signal. The calculated number of revolutions is given to the deviation calculating unit 21, which calculates the deviation by subtracting the number of revolutions from the indicated number of revolutions, and gives it to the PI control unit 22.
The PI control unit 22 calculates a control signal for performing PI control based on the given deviation, and provides it to the PWM circuit 23.

The detection signal of the hall sensor 17 is also supplied to the rotor position detection unit 27. The rotor position detection unit 27 detects the rotor position of the electric motor M that is a brushless DC motor based on the supplied detection signal, and the PWM circuit. 23.
The temperature sensor 28 detects the substrate temperature of the drive circuit 19 and gives the detection signal to the temperature determination unit 26. The temperature determination unit 26 determines whether or not the substrate temperature is higher than a predetermined temperature based on the given detection signal. If it is determined that the substrate temperature is higher than the predetermined temperature, an instruction for limiting the current flowing through the drive circuit 19. A signal is given to the motor rotation speed map unit 20.

The current detection circuit 29 detects the value of the current flowing through the electric motor M and supplies it to the PWM circuit 23.
The PWM circuit 23 outputs a pulse signal having a pulse width corresponding to the control signal given from the deviation calculating unit 21, the current value from the current detecting circuit 29, and the rotor position from the rotor position detecting unit 27, and a driving circuit. The 19 switching elements are turned on / off to drive the electric motor M.

Hereinafter, the control operation of changing the number of rotations of the electric motor M of the power steering apparatus having such a configuration will be described with reference to the flowchart of FIG.
The determination unit 25 of the electronic control unit ECU first reads a traffic jam signal from the car navigation device (S1), and determines whether or not the traffic jam signal indicates that the vehicle is located in the traffic jam section (S3). ). As a result, if the traffic jam signal indicates that the vehicle is located in the traffic jam section (S3; YES), the command rotation speed of the electric motor M is reset to the command rotation speed during normal steering. The motor rotation number map section is instructed (S15) and the process returns. As shown in FIG. 5A, the command rotation speed during normal steering is set so as to decrease as the vehicle speed increases.

  The determination unit 25 reads the winker operating signal from the CAN 30 or a signal indicating that the vehicle is stopped instead of the traffic jam signal. If the winker is operating or the vehicle is stopped, The command rotation speed of the motor M may be reset to the command rotation speed during normal steering.

If the traffic jam signal does not indicate that the vehicle is located in the traffic jam section (S3; NO), the determination unit 25 reads the night view signal (S5), and the night view signal detects an obstacle. It is determined whether or not rapid steering is necessary to avoid an obstacle (S7).
When the determination unit 25 determines that rapid steering is not necessary (S7; NO), the ABS signal is read (S9), the ABS signal indicates that the ABS is operating, and rapid steering is necessary. (S11). If sudden steering is not necessary (S11; NO), the process returns as it is.

When the determination unit 25 determines that rapid steering is necessary to avoid an obstacle (S7; YES), or when it is determined that rapid steering is necessary (S11; YES), the instruction rotation of the electric motor M is indicated. The motor rotation number map unit 20 is instructed to increase the number to the instruction rotation number in an emergency so that rapid steering is possible (S13), and the process returns.
As shown in FIG. 5B, the command rotation speed in an emergency is set to be constant regardless of the vehicle speed. That is, in the characteristic diagram of FIG. 4, the vehicle speed is set to be a characteristic at the lowest time or a characteristic having a higher rotational speed, and therefore relatively higher than the commanded rotational speed at the time of normal steering. .
The motor rotation speed map unit 20 increases the instruction rotation speed to the electric motor M by switching the reference map (motor rotation speed map).

It is explanatory drawing which shows typically the principal part structure of embodiment of the power steering device which concerns on this invention. It is a block diagram which shows the structural example of the electronic control unit shown in FIG. 1, a drive circuit, an electric motor, and a Hall sensor. It is a flowchart which shows the control operation | movement which changes the rotation speed of the electric motor of the power steering apparatus which concerns on this invention. It is a characteristic view which shows the example of a motor rotation speed map. It is explanatory drawing for demonstrating the control operation | movement which changes the rotation speed of the electric motor of the power steering apparatus which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Steering mechanism, 2 Steering wheel, 3 Steering shaft, 4 Pinion, 5 Rack shaft, 8 Steering angle sensor (encoder), 10 Power cylinder, 11 Piston, 13 Hydraulic control valve, 16 Oil pump, 19 Drive circuit, 20 Motor rotation Number map section (change means), 22 PI control section, 23 PWM circuit, 24 steering speed calculation section, 25 determination section (acquisition means, determination means), 30 CAN, 31 rotation speed calculation section, ECU electronic control unit, M Electric motor

Claims (3)

A steering speed of the steering member is detected, a target rotational speed of the electric motor is determined based on the detected steering speed and a given vehicle speed, and the electric motor is driven and controlled at the determined target rotational speed. In the power steering device that assists steering by the hydraulic pressure generated by the oil pump linked to the
A power steering system comprising: an acquisition unit that acquires information indicating a running state other than the speed of a vehicle or a surrounding situation; and a change unit that changes the target rotational speed based on the information acquired by the acquisition unit. apparatus.   Based on the information acquired by the acquisition means, the information processing apparatus further includes means for determining whether or not the state is in a state or situation in which rapid steering is necessary, and when the means determines that rapid steering is necessary, the changing means The power steering apparatus according to claim 1, wherein the power steering apparatus is configured to increase the target rotational speed.   The target rotational speed is recorded in a plurality of reference tables corresponding to the steering speed and the vehicle speed, and the changing means is configured to change the target rotational speed by switching the reference table. The power steering device according to claim 1 or 2.

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