JP4884843B2 - Power steering device - Google Patents

Description

  The present invention relates to an electric pump device, and more particularly to an electric pump device applied to a power steering device that assists a driver's steering.

  Conventionally, in the power steering apparatus disclosed in Patent Document 1, steering assist is provided by selectively supplying hydraulic pressure from a reversible pump driven by an electric motor to the left and right cylinder chambers of the power cylinder. Gaining power.

  This electric motor is driven only at the time of steering, and is stopped at the time of non-steering such as when traveling straight ahead, thereby reducing power consumption. Furthermore, by appropriately controlling the driving speed of the electric motor according to the steering speed and the steering torque, an appropriate pump discharge pressure corresponding to the steering situation is obtained. Therefore, the electric motor, that is, the reversible pump has a characteristic that the rotational speed control region is large.

When such a hydraulic pump is driven by an electric motor, unintended fluctuations in the pump rotation speed may occur depending on the load state of the hydraulic pump and the friction state of the electric motor. That is, in normal electric motor drive control, control is performed so that the maximum torque is generated by the command current applied to the electric motor.
JP-A-2005-41301

  However, in the above prior art, for example, when the drive load of the electric motor is temporarily increased due to an increase in the pump internal pressure, the rotation phase of the motor is delayed with respect to the command current timing. The motor cannot be used when the maximum torque is generated.

  As a result, the output torque of the motor temporarily decreases, and due to this torque decrease, the electric motor cannot counter the resistance of the pump internal pressure, the motor and the pump temporarily stop, the steering assist is interrupted, and the steering fee is interrupted. There was a problem that the ring might be deteriorated.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide an electric pump driving device capable of discharging a stable pressure even when a pump driving load changes according to a driving state. It is in.

In order to achieve the above object, in the power steering device of the present invention, a steering mechanism connected to a steered wheel , an electric motor that is a brushless motor that applies a steering assist torque to the steering mechanism, and the steering mechanism are provided. a torque sensor for detecting steering torque generated in the steering mechanism, the electric motor control means for outputting a drive command signal to the electric motor, the rotational speed measuring means for measuring the rotational speed before Symbol electric motor, the electric motor control means provided, based on said steering torque and the rotational speed of the electric motor, the measured and the torque current converting section for calculating a d-axis current target value and the q-axis current target value of the vector control by the rotational speed measuring means 90 degrees from the rotational phase of the d-axis current, which is the direction of the magnetic flux generated by the rotor of the electric motor, based on the rotational speed of the electric motor A motor rotation signal processing circuit that estimates the position of the rotation as the rotation phase of the q-axis current, and the rotation phase of the combined vector of the d-axis current target value and the q-axis current target value is the estimated rotation of the q-axis current. as a predetermined amount delayed from the phase, was to have a phase delay means that to correct the d-axis current target value or the q-axis current target value.

  Therefore, even if the pump driving load changes according to the driving state, an electric pump driving device that can discharge a stable pressure can be provided.

  Hereinafter, a pump device and a power steering device to which an electric pump device of the present invention is applied will be described based on embodiments shown in the drawings.

  FIG. 1 is a system diagram showing an overall configuration of a power steering apparatus according to Embodiment 1 of the present invention. 1 is a steering wheel, 2 is a steering shaft, 3 is a rack and pinion mechanism (steering mechanism), 5 is a power steering mechanism that assists the steering force of the driver, 6 is an external gear type bidirectional pump driven by a motor M, 7 is a steering wheel, 8 is a warning lamp for notifying the driver that a failure has occurred in the steering system, and 10 is a control unit (motor control circuit).

  The motor M is a brushless motor, and is provided with a motor rotation speed sensor M / Sen (rotation phase measuring means) including three Hall elements that detect the rotation angle of the electric motor.

  The bidirectional pump P that is a hydraulic source of the power steering mechanism 5 is provided on a hydraulic pipe 61 that communicates the first cylinder chamber 51 and the second cylinder chamber 52 of the power cylinder 5a (hydraulic power cylinder). When the driver operates the steering wheel 1, the rotation direction of the motor M is switched according to the operation direction, and the driver's steering is performed by supplying and discharging oil between the first cylinder chamber 51 and the second cylinder chamber 52. Assist force.

  Specifically, when the steering wheel 1 is steered to the right in the drawing, the motor M is driven in the direction in which the hydraulic pressure is supplied from the second cylinder chamber 52 to the first cylinder chamber 51 to move integrally with the rack shaft 54. The piston 53 is assisted to the second cylinder chamber 52 side.

  The hydraulic pipe 61 is provided with a bypass circuit 62 that communicates the first cylinder chamber 51 and the second cylinder chamber 52 without passing through the bidirectional pump P. On the bypass circuit 62, an electronically controlled fail-safe valve 4 that operates based on a command signal from the control unit 10 is provided.

  The fail-safe valve 4 uses a normally open valve that is closed when a voltage is supplied in response to a command signal from the control unit 10 and is open when no voltage is supplied.

  As a result, even if some abnormality occurs in the steering system and the power supply is shut down, the first cylinder chamber 51 and the second cylinder chamber 52 can be in communication with each other. Ensure steering.

  Further, the steering shaft 2 is provided with a torque sensor 12 for detecting the steering torque of the driver.

  The control unit 10 includes a steering torque signal from the torque sensor 12, an IGN signal from the ignition switch 13, an engine speed signal from the engine speed sensor 14, a vehicle speed signal from the vehicle speed sensor 15, and a motor speed sensor M / Sen. The motor rotation signal from is input. Based on these input signals, command signals are output to the motor M, the fail safe valve 4 and the warning lamp 8 of the bidirectional pump P.

  FIG. 2 is a block diagram showing the configuration inside the control unit 10. The power supply circuit watchdog timer 101 receives a voltage signal from the power supply 11 and an IGN signal from the ignition switch 13 and transmits / receives a signal to / from the main microcomputer 107.

  The engine speed processing circuit 102 outputs an engine speed signal from the engine speed sensor 14 to the main microcomputer 107. The torque sensor processing circuit 103 outputs a torque signal from the torque sensor 12 to the main microcomputer 107 and also outputs it to the sub-microcomputer 108.

  The vehicle speed signal processing circuit 104 outputs a vehicle speed signal from the vehicle speed sensor 15 to the main microcomputer 107. The diagnostic circuit 105 outputs a diagnostic signal input via the connector 16 to the main microcomputer. The CAN communication circuit 106 outputs a signal transmitted by the vehicle system CAN to the main microcomputer 107.

  The sub microcomputer 108 monitors the main microcomputer 107. When a failure occurs in the main microcomputer 107, a control signal can be output to the fail safe relay 109, the fail safe valve driving circuit 116, and the warning lamp driving circuit 117.

  The fail safe relay 109 cuts off the power supply for driving the electric motor when any failure occurs. The EEPROM 110 stores various data necessary for control and can update the data.

  The fail safe relay diagnosis input circuit 111 outputs an operation diagnosis signal for the fail safe relay 109 to the main microcomputer 107.

  The electric motor drive circuit 112 supplies a voltage to the motor M based on a command signal from the main microcomputer 107. The current monitor circuit 113 detects the current value of the motor M and outputs it to the main microcomputer 107. The motor terminal voltage circuit 114 outputs the terminal voltage of the motor M to the main microcomputer 107.

  Motor rotation signal processing circuit 115 estimates rotation speed ω and phase θest from three Hall elements provided in motor M, and outputs estimated rotation speed ω and estimated phase θest to main microcomputer 107. If a resolver or the like is provided, the absolute rotation angle may be detected directly.

  The fail safe valve drive circuit 116 outputs a drive signal to the fail safe valve 4 based on a command signal from the main microcomputer 107 or the sub microcomputer 108. The warning lamp drive circuit 117 outputs a command signal to the warning lamp 8 based on a command signal from the main microcomputer 107 or the sub-microcomputer 108.

  FIG. 3 is a schematic diagram illustrating the configuration of the pump unit according to the first embodiment. First, the configuration will be described. The hydraulic pipes 61a, 61b, 61c, 61d connect the cylinder chambers 51 to the bidirectional pump P. The bypass oil passages 62a, 62a ′, 62b, 62b ′ communicate with the hydraulic pipes 61b, 61c.

  The reservoir tanks 202a, 202b, and 205 supply oil to the bidirectional pump P and store drained oil. For convenience of explanation, it is shown that there are a plurality of reservoir tanks, but one reservoir tank may be provided. The check valves 201a and 201b are closed when hydraulic pressure is generated by the bidirectional pump P, and are opened when negative pressure is generated.

  Details of the return check valve 203 will be described later. The check valve 204 (corresponding to the check valve described in the claims) supplies drained oil to the reservoir tank 205, and the drain oil passage 63 passes through the return check valve 203, the reservoir tank 205, and the check valve 204. Connect.

  Here, the return check valve 203 will be described. The return check valve 203 includes a first return check valve 203a, a second return check valve 204a), a spool valve 210, and return springs 206a and 206b that urge the spool valve 210 to the center.

  The first return check valve 203a is provided with a first hydraulic chamber 207a having a connection port for the hydraulic pipes 61a and 61b, and a first piston chamber 208a having a connection port for the drain oil passage 63 and the bypass oil passage 62a ′. It has been. Similarly, the second return check valve 203b includes a second hydraulic chamber 207b having a connection port with the hydraulic pipes 61c and 61d, and a second piston chamber 208b having a connection port with the drain oil passage 63 and the bypass oil passage 62b ′. Is provided.

  The spool valve 210 is acted on by the urging force on the right side in the figure by the urging force of the return spring 206a, the oil pressure of the first hydraulic chamber 207a, and the oil pressure of the first piston chamber 208a. On the other hand, as the biasing force on the opposite side (left side in the figure), the biasing force by the return spring 207a, the hydraulic pressure in the second hydraulic chamber 207b, and the hydraulic pressure in the second piston chamber 208b act. Thereby, the position of the spool valve 210 is determined.

  The spool valve 210 is acted on by the urging force on the right side in the figure by the urging force of the return spring 206a, the oil pressure of the first hydraulic chamber 207a, and the oil pressure of the first piston chamber 208a. On the other hand, as the biasing force on the opposite side (left side in the figure), the biasing force by the return spring 207a, the hydraulic pressure in the second hydraulic chamber 207b, and the hydraulic pressure in the second piston chamber 208b act. Thereby, the position of the spool valve 210 is determined.

  FIG. 4 is a diagram illustrating the flow of oil during normal torque assist control, and FIG. 5 is an operation explanatory diagram illustrating the movement of the return check valve. In FIG. 4, a thick solid line indicates a high hydraulic pressure, and a thick dotted line indicates a low hydraulic pressure.

(When steering from the neutral position)
A description will be given of steering from a position where the hydraulic pressure in the first cylinder chamber 51 and the hydraulic pressure in the second cylinder chamber 52 are balanced. At the start of steering, the hydraulic pressure in the first cylinder chamber 51 and the hydraulic pressure in the second cylinder chamber 52 are in a balanced state. When assisting the rack shaft 54 to the right side in the figure by the driver's steering, the bidirectional pump P is driven to supply hydraulic pressure to the second cylinder chamber 52. Then, the hydraulic pipe 61c and the hydraulic pipe 61d become high hydraulic pressure.

  This high oil pressure is also supplied to the bypass oil passages 62b and 62d ', and the second piston chamber 208b becomes a high oil pressure. At this time, since the fail safe valve 4 is closed, as shown in FIG. 5B, the first piston chamber 208a and the second piston chamber 208b, and the first hydraulic chamber 207a and the second hydraulic chamber 207b are different. Pressure is generated and the spool valve 210 is moved to the left in FIG.

  Thereby, the bypass oil passage 62a ′ and the drain oil passage 63 are communicated with each other, and the first cylinder chamber 51 has a low hydraulic pressure released to the atmosphere. Torque assist steering is executed using this differential pressure.

[Control configuration of motor drive]
FIG. 6 is a control block diagram of a portion used for driving the motor in the control unit 10. The main microcomputer 107 includes a target torque calculation unit 70, a torque-current conversion unit 71, a PI control unit 72, a two-phase / three-phase conversion unit 73, a three-phase / two-phase conversion unit 74, and a rotation phase delay unit 75 (rotation phase delay unit 75). Means) and a correction unit 76.

  The target torque calculator 70 calculates a target torque T * of the motor M based on the steering torque signal and outputs it to the torque-current converter 71.

  Based on the rotational speed ω of the motor M, the torque-current converter 71 converts the target torque T * into d and q-axis current target values di * and qi * of the motor M, and converts the d-axis current target value di * into PI. It outputs to the control part 72, and outputs q-axis electric current target value qi * to the correction | amendment part 76. FIG.

  The correction unit 76 corrects the q-axis current target value qi * based on the retardation phase correction value θret set in advance in the rotational phase delay unit 75, and outputs it to the PI control unit 72.

  The PI control unit 72 performs PI control on the input d and q-axis current target values di * and qi * to calculate d and q-axis command currents dis and qis, and outputs them to the two-phase to three-phase conversion unit 73. To do. In order to cope with a pump rotation phase delay accompanying an increase in load, a value obtained by performing phase delay correction on the detected current of the motor M is used during PI control.

  The two-phase / three-phase converter 73 converts the d and q-axis command currents dis and qis into U, V, and W three-phase command voltages and outputs them to the motor drive circuit 112. At the time of conversion, in order to delay the phase of the motor M in response to the pump rotation phase delay, the U, V, and W phases are each delayed and output by the correction phase θesh.

  The three-phase to two-phase converter 74 converts the detected current values of the U, V, and W phases detected by the current monitor circuit 113 into two phases corresponding to the d and q axes, and is the same as the 2-3 phase converter 73. , Output to the PI control unit 72. At the time of conversion, the output is delayed by the correction phase θesh.

  The rotation phase delay unit 75 calculates a correction phase θesh based on the rotation speed ω estimated by the motor rotation signal processing circuit 115, the estimated phase θest, and a preset retardation angle correction value θret to obtain a two-phase-3. Output to phase conversion unit 73 and 3-phase-2 phase conversion unit 74. Further, the preset retardation phase correction value θret is output to the correction unit 76.

  The motor drive circuit 112 performs PWM conversion on the U, V, and W phase command voltages in the PWM output control unit 112a, and outputs the converted voltage to the motor M via the inverter circuit 112b.

[Rotational phase delay control structure]
FIG. 7 is a control block diagram of the rotation phase delay unit 75. The rotational phase delay unit 75 stores a preset retardation phase correction value θret, determines the direction of the rotational speed ω, and multiplies 1 by θret if it is forward rotation, and -1 by θret if it is reverse rotation. The correction phase θes h is calculated by taking the difference from the phase θest. Further, 1 / cos (θret) is calculated using the retarded phase correction value θret, and is output to the correction unit 76 as a q-axis current target correction coefficient.

  The rotational phase delay unit 75 calculates 1 / cos (θret) and delays the rotational phase when the rotational speed ω of the motor M is equal to or less than a predetermined value. In a state where the rotational speed ω of the motor M is low, the rotational speed detection accuracy of the motor M is lowered, so that it is difficult to correct a phase shift accompanying an increase in external load. By calculating 1 / cos (θret) only in a state where this correction is difficult, the motor M is used with high efficiency in the high rotation state.

[Pump phase lag and electrical angle lag correction]
FIG. 8 is a diagram illustrating the relationship between the estimated phase and the actual phase in the electrical angle of the motor M, and the control phase subjected to retardation correction. Due to the friction of the steering system such as the pump P, the estimated phase and the actual phase of the motor M are deviated by θmot, and the motor M has insufficient torque and a large torque fluctuation.

  Therefore, in Embodiment 1 of the present application, the phase of the command value qis of the q-axis current of the motor M is controlled in advance by delaying by the retardation phase correction value θret. That is, the q-axis current command value qis is delayed by θret with respect to the estimated phase of the motor M.

  This retarded phase correction value θret is an experimental value of phase delay due to steering system friction, and is a value set in advance for each vehicle. As described above, the control is performed in consideration of the assumed phase lag in advance, thereby compensating for the phase lag due to friction and avoiding a shortage of torque of the motor M and an increase in torque fluctuation.

  The motor M is a brushless motor, and the motor rotation speed sensor M / Sen is a hall element provided in the motor M. Therefore, although it is difficult to correct the rotational phase shift with high accuracy, an unintended torque drop of the motor M is prevented by performing the delay correction.

  The control unit 10 stops the rotation of the motor M at least when the vehicle is traveling straight. As in the present application, in a power steering device in which the motor M switches between rotation and stop, there are many low-speed states such as when the motor M starts rotating or immediately before it stops. In such a state, the pump P temporarily Suspension is likely to occur. By performing delay correction in this low-speed rotation state of the motor, unintentional temporary stop of the motor M is prevented.

[Change over time of phase delay compensation control]
FIG. 9 is a time chart showing the change over time of the phase delay compensation control.

(Time t1)
At time t1, the detected value of the motor rotation speed sensor M / Sen is 60 °. The estimated phase and the actual electrical angle are 60 °, and the control phase is controlled with a delay of θret (60 ° in the first embodiment).
At the same time, disturbance occurs, the shaft load of the pump P increases, and the torque of the motor M decreases. Along with this, the actual electrical angle is delayed and the inclination of θmot is reduced, and when the retardation correction is not performed, the generated torque Tmot of the motor M is reduced. On the other hand, when the retardation correction is performed, the torque of the motor M is also delayed in accordance with the rotational phase delay, and the motor torque Tmot is stabilized.

(Time t2)
When the detected value of the motor rotational speed sensor M / Sen becomes 120 ° at time t2 and the retard angle correction is not performed, the motor torque Tmot is recovered at this point.

[Effect of Example 1]
(1) In the first embodiment, the pump P that supplies hydraulic pressure, the motor M that drives the pump P, the control unit 10 that outputs a drive command signal to the motor M, and the rotation of the pump P or the motor M The motor rotation speed sensor M / Sen for measuring the speed, and the rotation phase of the drive command signal based on the rotation phase of the motor M measured by the motor rotation speed sensor M / Sen, the timing at which the motor M can be used with maximum efficiency. And a rotational phase delay unit 75 that delays a predetermined amount.

  As a result, when there is a deviation between the estimated phase of the motor M and the control phase in a direction in which the rotational phase of the motor M is delayed due to an increase in pump load or the like (a direction approaching a usable timing with maximum efficiency). The output torque of the motor M can be increased. Therefore, motor torque can be generated against the pump load to prevent or suppress unintended motor rotation fluctuations and pauses.

  (2) (3) In the power steering device using the rack and pinion and the hydraulic power steering device using the hydraulic power cylinder, the same operation and effect can be obtained by delaying the rotation phase as in (1). .

  A second embodiment will be described with reference to FIGS. Since the basic configuration is the same as that of the first embodiment, only different points will be described. In the first embodiment, the control is performed by delaying the phase of the q-axis current, but the second embodiment is different in that the phase of the combined vector of the d and q-axis currents is delayed by changing the magnitude of the d-axis current.

  FIG. 10 is a control block diagram of the control unit 10 in the second embodiment, and FIG. 11 is a control block diagram of the correction coefficient calculation unit 77.

  Based on the retardation phase correction value θret output from the rotational phase delay unit 75, the correction coefficient calculation unit 77 multiplies the q-axis current target value qi * by tan (θret), and d-axis current target value di * = qi * tan. (Θret) is output to the correction unit 78. The correction unit 78 corrects the d-axis current target value di * based on qi * tan (θret).

  FIG. 12 is a diagram illustrating the relationship between the estimated phase and the actual phase in the electrical angle of the motor M, and the control phase in which d-axis current correction is performed. By setting the d-axis current target value di * = qi * tan (θret), the combined vector of the d and q-axis currents is delayed in phase by θret from the q-axis estimated phase, and the same effect as in the first embodiment is obtained. be able to.

[Other embodiments]
The best mode for carrying out the present invention has been described based on each embodiment, but the specific configuration of the present invention is not limited to each embodiment and does not depart from the gist of the invention. Such design changes are included in the present invention.

  In the first and second embodiments, since the phase of the motor M is delayed by θret, the torque is also delayed. For this reason, the output torque may be lower than when using at the timing of maximum efficiency, and torque may be insufficient.

  Therefore, the target current of the motor M may be corrected to increase to compensate for the torque. A desired output torque can be obtained by increasing the torque reduction.

  For example, in the first embodiment, the motor rotation speed ω direction is multiplied by the retarded phase correction value θret. However, as shown in FIG. 13, a motor rotation speed ω-correction coefficient K1 map is used, and the correction coefficient K is multiplied by θret. The target current for the motor M may be increased by setting the q-axis current target correction coefficient to 1 / cos (K1θret).

  Further, in the second embodiment, as shown in FIG. 14, after the q-axis current target value qi * is multiplied by tan (θret), the motor M is further multiplied by the correction coefficient K2 read from the motor rotation speed ω-correction coefficient K2 map. The target current may be increased and corrected.

  The control unit 10 further includes learning means for learning a periodic decrease in the rotational speed of the motor M, and the control unit 10 adjusts the timing of the decrease in the periodic rotational speed ω learned by the learning means. The target current may be corrected to increase.

  When the gear of the pump P is distorted, the pump friction changes at the distorted portion, and this friction change occurs periodically with the rotation of the pump. By learning this periodic friction change and correcting the target current of the motor M, smoother motor control can be performed.

  Further, technical ideas other than the claims that can be grasped from the above-described embodiments and examples will be described together with the effects thereof.

(A) In the electric pump device according to claim 1,
The electric pump device, wherein the phase delay means delays the rotational phase of the drive command signal when the rotational speed of the electric motor is equal to or less than a predetermined value.

  In a state where the rotational speed of the electric motor is low, the rotational speed detection accuracy of the motor is lowered, so that it is difficult to correct the phase shift of the drive command signal accompanying an increase in the external load. By performing the delay correction only in a state where this correction is difficult, the motor can be used with high efficiency in the high rotation state.

(B) In the electric pump device according to claim 1 or (a),
The electric pump device characterized in that the motor control circuit increases and corrects the drive command signal in a state where the rotational phase of the drive command signal is sent by the phase delay means.

  In the state where the rotational phase of the drive command signal is delayed, the output torque is reduced compared to when it is used at the timing of maximum efficiency. Therefore, the desired output torque can be obtained by increasing the torque reduction. Can do.

(C) In the electric pump device according to claim 1,
The electric motor is a brushless motor,
The electric pump device, wherein the rotational phase detection means is a Hall element that is provided in the brushless motor and detects a rotational position of a rotation shaft of the brushless motor.

  When a Hall element having a low detection accuracy is used, it is difficult to correct a rotational phase shift with high accuracy. However, an unintended motor torque drop can be prevented by performing a delay correction.

(2) The electric pump device according to claim 1,
Learning means for learning a decrease in the periodic rotational speed of the electric motor;
The electric pump device, wherein the motor control circuit increases and corrects the drive command signal in accordance with a generation timing of a periodic rotational speed decrease learned by the learning unit.

  When the pump gear is distorted, the pump friction changes at the distorted portion, and this friction change periodically occurs as the pump rotates. By learning this periodic friction change and correcting the drive command signal, smoother motor control can be performed.

(E) In the power steering device according to claim 2,
The phase delay means delays the rotational phase of the drive command signal when the rotational speed of the electric motor is a predetermined value or less.

  In a state where the rotational speed of the electric motor is low, the rotational speed detection accuracy of the motor is lowered, so that it is difficult to correct the phase shift of the drive command signal accompanying an increase in the external load. By performing delay correction only in a state where this correction is difficult, the motor can be used with high efficiency in a high rotation state.

(F) In the power steering device according to claim 2 or (e),
The motor control circuit increases and corrects the drive command signal when the rotational phase of the drive command signal is delayed by the phase delay means.

  In the state where the rotational phase of the drive command signal is sent, the output torque is lower than when using at the maximum efficiency timing. Therefore, the desired output torque can be obtained by correcting the increase in this torque decrease. it can.

(G) In the power steering device according to claim 2,
The electric motor is a brushless motor,
The power steering device according to claim 1, wherein the rotational phase detecting means is a Hall element that is provided in the brushless motor and detects a rotational position of a rotational shaft of the brushless motor.

  When a Hall element having a low detection accuracy is used, it is difficult to correct a high-precision na rotational phase shift, but by performing a delay correction, an unintended motor torque drop can be prevented.

(H) The power steering device according to claim 2 is:
Learning means for learning a decrease in the periodic rotational speed of the electric motor;
The power control apparatus, wherein the motor control circuit increases and corrects the drive command signal in accordance with a generation timing of a periodic rotational speed learned by the learning unit.

  When the gear of the steering mechanism is distorted, the friction changes at the distorted portion, and the friction change periodically occurs as the gear rotates. By learning this periodic friction change and correcting the drive command signal, smoother motor control can be performed.

(I) In the power steering device according to claim 3,
The electric motor stops rotation at least when the vehicle is in a straight traveling state.

  In a power steering device in which the electric motor switches between rotation and stop, a state where the motor rotation speed is low often occurs, such as at the start of rotation of the electric motor or immediately before stopping, and the pump is likely to be temporarily stopped in such a state. . By performing delay correction in this low-speed rotation state of the motor, it is possible to prevent unintentional temporary stop of the motor.

1 is a system configuration diagram of a power steering device in Embodiment 1. FIG. FIG. 3 is a block diagram illustrating a configuration inside a control unit according to the first embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a pump unit according to the first embodiment. It is a figure which shows the flow of the oil at the time of the normal torque assist control in Example 1. FIG. It is operation | movement explanatory drawing which shows a motion of the return check valve in Example 1. FIG. It is a control block diagram of the part used for motor drive in a control unit. It is a control block diagram of a rotation phase delay part. It is a figure which shows the relationship of the control phase which performed the delay phase correction | amendment and the actual phase in the electrical angle of a motor. It is a time chart which shows a time-dependent change of phase delay compensation control. 6 is a control block diagram of a control unit in Embodiment 2. FIG. FIG. 10 is a control block diagram of a correction coefficient calculation unit in the second embodiment. It is a figure which shows the relationship between the control phase which performed the estimated phase in the electrical angle of a motor, an actual phase, and d-axis current correction | amendment. It is a figure which shows another Example. It is a figure which shows another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering shaft 4 Fail safe valve 5 Power steering mechanism 5a Power cylinder 8 Warning lamp 10 Control unit 11 Power supply 12 Torque sensor 13 Ignition switch 14 Engine speed sensor 15 Vehicle speed sensor 16 Connector 51, 52 Cylinder chamber 53 Piston 54 Rack Shaft 61 Hydraulic pipe 62 Bypass circuit 63 Drain oil passage 70 Target torque calculation unit 71 Current conversion unit 72 Control unit 73 Two-phase to three-phase conversion unit 74 Three-phase to two-phase conversion unit 75 Rotation phase delay unit 76 Correction unit 77 Correction coefficient calculation unit 78 Correction unit 101 Power supply circuit watchdog timer 102 Engine speed processing circuit 103 Torque sensor processing circuit 104 Vehicle speed signal processing circuit 105 Diagnostic circuit 106 Communication circuit 107 Main microcomputer 10 Sub-microcomputer 109 Fail safe relay 111 Fail safe relay diagnostic input circuit 112 Motor drive circuit 112a Output control unit 112b Inverter circuit 113 Current monitor circuit 114 Motor terminal voltage circuit 115 Motor rotation signal processing circuit 115 Motor rotation signal processing circuit 116 Fail safe valve drive Circuit 117 Warning lamp drive circuit 201a, 201b Check valve 202a, 202b, 205 Reservoir tank 203 Return check valve 204 Check valve 205 Reservoir tank 206a, 206b Return spring 207a, 207b Hydraulic chamber 208a, 208b Piston chamber 210 Spool valve M Motor M / Sen Motor speed sensor P Pump

Claims (1)

A steering mechanism connected to the steering wheel;
An electric motor that is a brushless motor that applies a steering assist torque to the steering mechanism ;
A torque sensor provided in the steering mechanism for detecting a steering torque generated in the steering mechanism;
Electric motor control means for outputting a drive command signal to the electric motor ;
A rotational speed measuring means for measuring the rotational speed before Symbol electric motor,
A torque current converter provided in the electric motor control means for calculating a d-axis current target value and a q-axis current target value for vector control based on the steering torque and the rotational speed of the electric motor;
Based on the rotational speed of the electric motor measured by the rotational speed measuring means, the rotation of the q-axis current is performed at a position advanced 90 degrees from the rotational phase of the d-axis current, which is the direction of the magnetic flux generated by the rotor of the electric motor. A motor rotation signal processing circuit that estimates the phase;
The d-axis current target value or the q-axis is set so that the rotational phase of the combined vector of the d-axis current target value and the q-axis current target value is delayed by a predetermined amount from the estimated rotational phase of the q-axis current. and phase delay means that to correct the current target value,
A power steering apparatus comprising:

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