JP2014193635A - Hydraulic power steering device controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power steering device controller capable of suppressing reduction in steering feeling.SOLUTION: A microcomputer 71 temporarily executes a reverse rotation control if a target rotational speed calculated on the basis of the steering angle θs and a vehicle speed SPD is higher than a predetermined forward rotational speed and a state in which an actual rotational speed of a motor 41 is lower than a rotational speed lower limit continues for predetermined determination time despite supply of sufficient drive power to the motor 41 in a situation in which an oil temperature of working oil is quite low. Furthermore, if determining that a load for reversely rotating the motor 41 based on an actual current value Im is high after continuing the reverse rotation of the motor 41 for first reverse rotation time at a time of executing the reverse rotation control, the microcomputer 71 further continues the reverse rotation of the motor 41 for second reverse rotation time.

Description

  The present invention relates to a control device for a hydraulic power steering apparatus.

  2. Description of the Related Art Conventionally, a hydraulic power steering device that applies an assist force to a steering system using a hydraulic actuator such as a hydraulic cylinder is widely known. For example, Patent Document 1 discloses a hydraulic power steering device using an electric pump that generates hydraulic pressure by driving a motor as a hydraulic pressure source of a hydraulic actuator. In such a hydraulic power steering device, even when the steering operation is not performed, the electric pump is driven at a relatively low rotation speed (standby rotation speed), so that a quick assist force can be quickly applied. The improvement of the nature is aimed at.

JP 2008-238882 A

  By the way, in the hydraulic power steering apparatus as described above, usually, when hydraulic fluid is supplied to the hydraulic actuator, the motor is rotated only in one direction (forward rotation). For this reason, it is difficult to properly supply hydraulic oil from the electric pump to the hydraulic actuator in a situation where the load for causing the motor to rotate in the forward direction is very high and the actual rotational speed of the motor does not rise normally corresponding to the target rotational speed. Thus, there is a problem that the steering feeling is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for a hydraulic power steering apparatus that can suppress a decrease in steering feeling.

  A control device for a hydraulic power steering device that solves the above-described problem is to generate an assist force by supplying hydraulic oil to a hydraulic actuator using an electric pump. When the actual rotational speed of the motor does not increase normally corresponding to the target rotational speed of the motor, the hydraulic oil is supplied to the hydraulic actuator by rotating the motor forward. The gist is to perform reverse rotation control to reversely rotate the motor in another direction opposite to the one direction.

  According to the above configuration, when the actual rotational speed of the motor does not increase normally corresponding to the target rotational speed and it is estimated that the load for rotating the motor in the forward direction is excessive, It can be expected that the excessive state of the load is improved by changing the state of the pump. And, since the load to rotate the motor in the reverse direction temporarily by rotating the motor temporarily becomes small, it becomes possible to supply hydraulic oil appropriately to the hydraulic actuator by rotating the motor in the normal direction again. A decrease in steering feeling can be suppressed.

In the control device for the hydraulic power steering device, it is preferable to allow the reverse rotation control to be executed only when the motor is started.
Here, as a situation where the load for causing the motor to rotate forward becomes excessive and the actual rotational speed of the motor does not rise normally corresponding to the target rotational speed, for example, when the ignition switch (IG) is turned on and the motor starts up A situation in which the steering wheel is further cut from a state in which the hydraulic oil temperature is extremely low and the steering angle is in the vicinity of the maximum steering angle (steering end) is conceivable. That is, when the oil temperature of the working oil is extremely low, the viscosity of the working oil becomes high, so that the working oil hardly flows and the load on the motor becomes high. Further, even if it is attempted to cut further from the steering end, it is almost impossible to pour hydraulic oil into the hydraulic actuator, so the load on the motor becomes high. As a result of excessive load that causes the motor to rotate forward, the start-up of the motor may be delayed, and responsiveness may be reduced. On the other hand, when the motor is rotated in the reverse direction, the hydraulic oil is not supplied to the hydraulic actuator, so that the load is lower than that in the case where the motor is rotated in the forward direction, and the motor can be rotated at a high rotational speed. And since a lot of frictional heat can be generated by a pump etc. by reverse rotation of the motor at a high rotation speed, the oil temperature of the hydraulic oil is raised and the situation of excessive load for normal rotation of the motor is improved. It becomes possible. Therefore, it is possible to suppress a decrease in responsiveness by executing the reverse rotation control at the time of startup as in the above configuration.

  In addition, when the IG is turned on as described above, the situation in which the steering wheel is further cut from the state at the steering end is, for example, if the vehicle does not depart from the garage when it is steered to the vicinity of the steering end. This is likely to occur when it is not possible, and may occur repeatedly. Compared to this, a situation in which the actual rotational speed becomes less than the lower limit rotational speed is less likely to occur after the start of the motor is completed and the motor rotates normally. And since execution of reverse rotation control cannot provide an appropriate assist force, execution of reverse rotation control is not preferable from the viewpoint of improving reliability. Therefore, by allowing the reverse rotation control to be executed only at the time of starting the motor as in the above configuration, it is possible to improve reliability while suppressing a decrease in responsiveness.

In the control device of the hydraulic power steering device, it is preferable to determine whether or not the motor is activated based on an oil temperature of the hydraulic oil.
According to the said structure, it is determined whether it is at the time of starting of a motor based on the oil temperature of hydraulic fluid, ie, whether execution of reverse rotation control is permitted. Therefore, when the oil temperature of the hydraulic oil is high and the load for rotating the motor in the forward direction is low, the reverse rotation control is not executed and the motor is continuously rotated in the forward direction, so that the responsiveness can be further improved. .

  In the control device of the hydraulic power steering device, the reverse rotation control is further performed when the load for rotating the motor reversely after the reverse rotation of the motor continues for the first reverse rotation time is further increased by the second reverse rotation. It is preferable that the motor is reversely rotated continuously for a period of time.

  According to the above configuration, when the motor load is high after continuously rotating the motor for the first predetermined time, that is, when it is estimated that the hydraulic oil temperature is still low and its viscosity is high, the motor is further reduced. Reverse. Therefore, the oil temperature of the hydraulic oil can be raised quickly.

  In the control device for the hydraulic power steering apparatus, the target rotational speed when the motor is further reversely rotated after the first reverse rotation time is continued for the first reverse rotation time continues for the first reverse rotation time. It is preferable to set the rotational speed higher than the target rotational speed when the motor is reversely rotated.

According to the said structure, the oil temperature of hydraulic fluid can be raised more rapidly.
In the control device of the hydraulic power steering device, it is preferable that the reverse rotation control is prohibited when the actual current value of the electric pump is less than a predetermined current value corresponding to a target rotational speed.

  In the control device of the hydraulic power steering device, a drive circuit for supplying drive power to the motor is configured by a switching element that is turned on / off based on a duty ratio of a pulse signal subjected to pulse width modulation control, When the duty ratio is less than a predetermined duty ratio corresponding to the target rotational speed, it is preferable to prohibit the execution of the reverse rotation control.

  According to each of the above configurations, when the actual current value is less than the predetermined current value, or when the duty ratio is the predetermined duty ratio, that is, necessary for the actual rotational speed of the motor to rise normally corresponding to the target rotational speed. When sufficient driving power is not sufficiently supplied to the motor, the reverse rotation control is not executed. Therefore, the reverse rotation control can be executed by accurately determining a situation where the actual rotation speed does not normally increase due to a high load for rotating the motor in the forward direction.

In the control device for the hydraulic power steering apparatus, it is preferable that the motor is stopped when the number of executions of the reverse rotation control exceeds a predetermined number.
If the actual rotation speed of the motor does not rise normally in response to the target rotation speed even if the reverse rotation control is executed multiple times, it is estimated that an abnormality that cannot be improved by rotating the motor back to the electric pump has occurred. it can. Therefore, by stopping the motor when the number of executions of the reverse rotation control exceeds a predetermined number as in the above configuration, for example, wasteful power consumption can be suppressed.

  According to the present invention, it is possible to suppress a decrease in steering feeling.

The schematic block diagram of a hydraulic power steering device. The block diagram of a hydraulic power steering device. The flowchart which shows the control procedure of the electric pump of 1st Embodiment. The flowchart which shows the process sequence of reverse rotation control. The flowchart which shows the control procedure of the electric pump of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment of a hydraulic power steering apparatus will be described with reference to the drawings.
As shown in FIG. 1, the hydraulic power steering apparatus 1 includes a steering shaft 3 to which a steering wheel 2 is fixed, a rack shaft 5 that reciprocates in the axial direction according to the rotation of the steering shaft 3, and the rack shaft 5 reciprocates. And a substantially cylindrical rack housing 6 that is movably inserted therethrough. The steering shaft 3 is configured by connecting a column shaft 7, an intermediate shaft 8, and a pinion shaft 9 in this order from the steering wheel 2 side.

  The rack shaft 5 and the pinion shaft 9 are arranged in the rack housing 6 with a predetermined crossing angle, and the rack teeth 5a formed on the rack shaft 5 and the pinion teeth 9a formed on the pinion shaft 9 are meshed with each other. Thus, the rack and pinion mechanism 11 is configured. Further, tie rods 12 are connected to both ends of the rack shaft 5, and the tip of the tie rod 12 is connected to a knuckle (not shown) to which the steered wheels 13 are assembled. Therefore, in the hydraulic power steering apparatus 1, the rotation of the steering shaft 3 accompanying the steering operation is converted into the axial movement of the rack shaft 5 by the rack and pinion mechanism 11, and this axial movement is transmitted to the knuckle through the tie rod 12. Thus, the turning angle of the steered wheels 13, that is, the traveling direction of the vehicle is changed.

  The hydraulic power steering apparatus 1 includes a hydraulic cylinder 21 as a hydraulic actuator that generates an assist force that assists the steering operation, and an electric pump 22 that supplies hydraulic oil to the hydraulic cylinder 21. The hydraulic power steering device 1 also includes a switching valve 24 that controls the supply and discharge of hydraulic oil to and from the hydraulic cylinder 21 and a storage tank 25 that stores the hydraulic oil supplied to and discharged from the hydraulic cylinder 21 by the electric pump 22. ing.

  The hydraulic cylinder 21 includes a cylindrical cylinder tube 31 constituted by a part of the rack housing 6. That is, the rack shaft 5 is inserted into the cylinder tube 31 so as to be able to reciprocate. The hydraulic cylinder 21 includes a piston 34 that divides the cylinder tube 31 into a first hydraulic chamber 32 and a second hydraulic chamber 33, and the piston 34 is fixed to the rack shaft 5 so as to be movable in the axial direction. Has been.

  The electric pump 22 includes a motor 41 serving as a drive source, a pump 42 that generates hydraulic pressure by being driven by the motor 41, and an ECU 43 that controls the operation of the motor 41. The motor 41 of the present embodiment employs a brushed DC motor, and the pump 42 employs a gear pump. In the electric pump 22, the hydraulic oil is supplied to the hydraulic cylinder 21 by driving the pump 42 by rotating the motor 41 in one preset direction (forward rotation).

  The electric pump 22 has an integrated structure in which the ECU 43 is sandwiched between the motor 41 and the pump 42. The suction port (not shown) of the electric pump 22 is connected to the storage tank 25 via a suction oil passage 45. Furthermore, the electric pump 22 is provided with a relief valve 46 (pressure adjusting valve). When the discharge pressure of the electric pump 22 exceeds a preset predetermined pressure, hydraulic fluid is transferred from the relief valve 46 to the storage tank 25. It is supposed to be discharged.

  The switching valve 24 is configured as a known rotary valve that controls supply and discharge of hydraulic oil to and from the first and second hydraulic chambers 32 and 33 of the hydraulic cylinder 21 in conjunction with the steering operation. Specifically, the switching valve 24 is provided with a supply port 51, a discharge port 52, and first and second supply / discharge ports 53 and 54. The supply port 51 is connected to a discharge port (not shown) of the electric pump 22 via a supply oil passage 55. The discharge port 52 is connected to the storage tank 25 via a discharge oil passage 56. The first supply / discharge port 53 is connected to the first hydraulic chamber 32 via the first supply / discharge oil passage 57, and the second supply / discharge port 54 is connected to the second hydraulic pressure via the second supply / discharge oil passage 58. It is connected to the chamber 33.

  In the hydraulic power steering apparatus 1 configured as described above, the hydraulic oil sucked up from the storage tank 25 by the electric pump 22 is supplied to the switching valve 24 via the supply oil passage 55. The hydraulic oil supplied to the switching valve 24 is first and second via either one of the first and second oil supply / discharge oil passages 57 and 58 according to the steering operation (steering direction) of the driver. It is supplied to one of the hydraulic chambers 32 and 33. At this time, the hydraulic oil is discharged from the other one of the first and second hydraulic chambers 32, 33, and this hydraulic oil is the other of the first and second oil supply / discharge oil passages 57, 58, the switching valve 24 and the discharge oil passage. It is discharged to the storage tank 25 through 56. As a result, a hydraulic pressure difference is generated between the first hydraulic chamber 32 and the second hydraulic chamber 33, and the rack shaft 5 moves in the axial direction together with the piston 34 based on the hydraulic pressure difference, thereby assisting the steering operation. . When the steering wheel 2 is steered at the neutral position, the hydraulic oil supplied from the electric pump 22 to the supply port 51 is discharged to the storage tank 25 through the discharge port 52 and the discharge oil passage 56.

Next, the electrical configuration of the hydraulic power steering apparatus will be described.
The electric pump 22 is connected to a CAN (in-vehicle network) 61. Sensors such as a steering sensor 62 and a vehicle speed sensor 63 are connected to the CAN 61, and state quantities such as the steering angle θs of the steering wheel 2 and the vehicle speed SPD are transmitted. The ECU 43 controls the operation of the electric pump 22 (motor 41) based on each state quantity obtained via the CAN 61.

  More specifically, as shown in FIG. 2, the ECU 43 includes a microcomputer 71 that outputs a motor control signal and a drive circuit 72 that supplies drive power to the motor 41 based on the motor control signal. The drive circuit 72 is connected to an in-vehicle power source (battery) 73 mounted on the vehicle.

  The drive circuit 72 employs a known PWM inverter in which FETs (field effect transistors) 74a to 74d as four switching elements are connected in a bridge shape. The motor control signal output from the microcomputer 71 is a pulse signal that is PWM (pulse width modulation) controlled, and is applied to the gate terminals of the FETs 74a to 74d. The FETs 74 a to 74 d are turned on / off based on the duty ratio of the pulse signal, so that driving power based on the duty ratio and the voltage of the in-vehicle power supply 73 is supplied to the motor 41.

  The microcomputer 71 is connected to a current sensor 76 that detects an actual current value Im flowing through the motor 41 (electric pump 22) and a rotation angle sensor 77 that detects a rotation angle θm of the motor 41. The microcomputer 71 is connected to a temperature sensor 78 that detects the ambient temperature TMP in the electric pump 22. Since the electric pump 22 has a structure in which the motor 41, the pump 42, and the ECU 43 are integrated as described above, the ambient temperature TMP is a value correlated with the oil temperature of the hydraulic oil in the pump 42. ing. The microcomputer 71 acquires each state quantity from each sensor and the CAN 61 at a predetermined sampling period. Then, the microcomputer 71 controls the operation of the motor 41 through the supply of driving power by outputting a motor control signal based on each of these state quantities.

  More specifically, the microcomputer 71 controls the rotational speed so that the actual rotational speed (rotational speed) N of the motor 41 (pump 42) becomes the target rotational speed N * calculated based on the steering angle θs and the vehicle speed SPD. By executing (speed feedback control), a motor control signal is output to control the operation of the motor 41. The actual rotational speed N is calculated based on the rotational speed obtained by differentiating the rotational angle θm. Further, a relatively low standby rotational speed is preset as the minimum value for the target rotational speed N *, and the target rotational speed N * is determined from the standby rotational speed according to the steering speed ωs and the vehicle speed SPD obtained by differentiating the steering angle θs. A higher target rotational speed N * is calculated. Specifically, the target rotational speed N * is calculated to be higher as the absolute value of the steering speed ωs is larger and as the vehicle speed SPD is lower. A motor control signal is output from the microcomputer 71 to the drive circuit 72, and the drive power based on the motor control signal is supplied to the motor 41 by the drive circuit 72, so that the pump 42 is rotated according to the rotation of the motor 41. Driven. Accordingly, hydraulic oil is supplied to the hydraulic cylinder 21 in accordance with the steering operation, and the hydraulic pressure generated in the hydraulic cylinder 21 is applied to the steering system as an assist force.

  Here, in a situation where the load for causing the motor 41 to rotate forward is excessive, the actual rotational speed N of the motor 41 may not increase normally. As such a situation, for example, when the ignition switch (IG) is turned on and the motor 41 is started, the steering oil is further steered from the state where the hydraulic oil temperature is extremely low and the steering angle is in the vicinity of the maximum steering angle (steering end). A situation where the wheel 2 is cut is conceivable. That is, when the oil temperature of the hydraulic oil is extremely low, the viscosity of the hydraulic oil becomes high and the hydraulic oil becomes difficult to flow, so the load on the motor 41 increases. Further, when further cutting is performed from the steering end, no more hydraulic oil can flow into the first hydraulic chamber 32 or the second hydraulic chamber 33 of the hydraulic cylinder 21, and the hydraulic oil does not flow unless the relief valve 46 is opened. Therefore, the load on the motor 41 is increased. As a result of excessive load that causes the motor 41 to rotate forward, the start-up of the motor 41 may be delayed, and responsiveness may be reduced. On the other hand, when the motor 41 is rotated in the opposite direction opposite to the one direction, the hydraulic oil is not supplied to the hydraulic cylinder 21, so the load is lower and the rotation is higher than when the motor 41 is rotated forward. The motor can be rotated by a number. And since the motor 41 reversely rotates at a high rotational speed, a lot of frictional heat can be generated by the pump 42 and the like, so that the oil temperature of the hydraulic oil is raised and the load for rotating the motor 41 forward is reduced. Is possible.

  In consideration of this point, the microcomputer 71 (ECU 43) of the present embodiment temporarily stops the motor 41 if the actual rotational speed N does not rise normally corresponding to the target rotational speed N * when the motor 41 is started. Reverse rotation control is performed to reversely rotate. Note that the control for rotating the motor 41 forward so that the actual rotational speed N follows the target rotational speed N * calculated based on the steering angle θs and the vehicle speed SPD as described above is referred to as normal rotational control (normal control).

Specifically, the microcomputer 71 is configured so that the target rotational speed N * is higher than the predetermined positive rotational speed N_p and sufficient driving power is supplied to the motor 41 under a situation where the oil temperature of the hydraulic oil is extremely low. Regardless, the state where the actual rotational speed N is less than the lower limit rotational speed N_lo is a predetermined determination time (for example,
When the operation continues for about 3 seconds, reverse rotation control is temporarily executed. The predetermined positive rotation speed N_p is set to the lowest value (for example, about 800 rpm) in the rotation speed range in which the assist force can be quickly applied in response to the driver's steering, and the lower limit rotation speed N_lo is It is set to a value (for example, about 500 rpm) sufficiently smaller than a predetermined positive rotation speed N_p. When the microcomputer 71 determines that the actual rotation speed N is equal to or greater than the lower limit rotation speed N_lo or the hydraulic oil temperature is high, and the start of the motor 41 is completed, the microcomputer 71 prohibits execution of reverse rotation control. .

  On the other hand, the microcomputer 71 stops the motor 41 when the number of executions of the reverse rotation control exceeds a predetermined number (for example, three times) without starting the motor 41. The microcomputer 71 of the present embodiment lights a warning lamp (not shown) when the motor 41 is stopped.

  More specifically, the microcomputer 71 determines whether or not the oil temperature is extremely low using the ambient temperature TMP correlated with the oil temperature of the hydraulic oil as described above. Specifically, the microcomputer 71 determines that the oil temperature of the hydraulic oil is extremely low when the ambient temperature TMP is equal to or lower than the low temperature threshold value TMP_lo. Then, when the ambient temperature TMP becomes higher than the low temperature threshold value TMP_lo, the microcomputer 71 determines that the oil temperature of the hydraulic oil has increased and the activation of the motor 41 has been completed. The low temperature threshold value TMP_lo is a temperature at which the viscosity of the hydraulic oil increases until the actual rotational speed N becomes less than the lower limit rotational speed N_lo when the steering wheel 2 is further cut from the state at the steering end. It is set to about 20 °.

  Further, the microcomputer 71 determines whether or not sufficient drive power is supplied to the motor 41 using the actual current value Im detected by the current sensor 76 and the duty ratio α indicated by the motor control signal (pulse signal). judge. Specifically, when the actual current value Im is equal to or greater than the predetermined current value I_th corresponding to the predetermined positive rotation speed N_p, and the duty ratio α is equal to or greater than the predetermined duty ratio α_th corresponding to the predetermined positive rotation speed N_p. Then, it is determined that sufficient drive power is supplied to the motor 41. The predetermined current value I_th is a value sufficient for the actual rotation speed N to rise to a predetermined positive rotation speed N_p unless the load on the motor 41 is excessive, and is set to about 10 A, for example. Further, the predetermined duty ratio α_th is a value sufficient for the actual rotation speed N to rise to a predetermined positive rotation speed N_p unless the load of the motor 41 is excessive, and is set to about 10%, for example.

  In the reverse rotation control, first, the microcomputer 71 continues the motor 41 for the first reverse rotation time (for example, 5 sec) with a predetermined first reverse rotation speed N_g1 (for example, about 2500 rpm) as a target rotation speed. After reverse rotation, it is determined whether the load for reverse rotation of the motor 41 is high. If the microcomputer 71 determines that the load for reversely rotating the motor 41 is high, the microcomputer 71 further sets a predetermined second reverse rotational speed N_g2 (for example, a rotational speed higher than the predetermined first reverse rotational speed N_g1) (for example, The motor 41 is rotated in the reverse direction continuously for the second reverse rotation time (for example, 5 seconds), with the target rotation speed being about 3000 rpm. Note that the microcomputer 71 according to the present embodiment determines whether or not the load for reversely rotating the motor 41 is high when the actual current value Im is equal to or greater than a predetermined high load determination value I_hi. The high load determination value I_hi is a current value required to reversely rotate the motor 41 at a predetermined second reverse rotation speed N_g2 when the oil temperature is extremely low, and is set to, for example, about 20A.

Next, the control procedure of the electric pump by the microcomputer will be described.
As shown in FIG. 3, when the IG is turned on, the microcomputer 71 turns on the activation flag F_su indicating that the motor 41 is activated as an initial process, and performs reverse rotation provided in the microcomputer 71. The counter value C of the retry counter indicating the number of control executions is cleared (zero), and the timer value t1 of the first timer is cleared (step 101). When this initial process is completed, each state quantity such as the steering angle θs (steering speed ωs), the vehicle speed SPD, the ambient temperature TMP, the rotation angle θm, and the actual current value Im is acquired (step 102), and the forward rotation control is executed. (Step 103). Subsequently, it is determined whether or not the activation flag F_su is in an on state (step 104). If the activation flag F_su is in an on state, that is, when the motor 41 is activated (step 104: YES), the atmosphere It is determined whether or not the temperature TMP is equal to or lower than the low temperature threshold value TMP_lo (step 105). When the activation flag F_su is in an off state, that is, when the activation of the motor 41 is completed (step 104: NO), the process proceeds to step 102. That is, after it is determined that the start of the motor 41 is completed, the operations of the motor 41 are controlled so that the assist force corresponding to the steering operation is applied to the steering system by repeatedly executing the processes of steps 102 and 103. To do.

  When the ambient temperature TMP is equal to or lower than the low temperature threshold value TMP_lo and the oil temperature is extremely low (step 105: YES), the microcomputer 71 determines whether or not the target rotational speed N * is greater than a predetermined positive rotational speed N_p. (Step 106). Subsequently, when the target rotational speed N * is larger than the predetermined positive rotational speed N_p (step 106: YES), it is determined whether or not the actual rotational speed N is less than the lower limit rotational speed N_lo (step 107). If the actual rotational speed N is equal to or higher than the lower limit rotational speed N_lo (step 107: NO), it is determined that the motor 41 has been started, and the start flag F_su is turned off (step 108). Even when the ambient temperature TMP is higher than the low temperature threshold value TMP_lo (step 105: NO), the process proceeds to step 108 and the activation flag F_su is turned off.

  On the other hand, when the actual rotational speed N is less than the lower limit rotational speed N_lo (step 107: YES), the microcomputer 71 determines whether or not sufficient drive power is supplied to the motor 41. That is, it is determined whether or not the actual current value Im is larger than the predetermined current value I_th (step 109). If the actual current value Im is larger than the predetermined current value I_th (step 109: YES), step 103 It is determined whether or not the duty ratio α indicated in the motor control signal output when the forward rotation control is executed is larger than a predetermined duty ratio α_th (step 110). When the duty ratio α is larger than the predetermined duty ratio α_th (step 110: YES), the timer value t1 of the first timer is incremented (step 111), and the timer value t1 is set to the predetermined determination time. It is determined whether it is larger than the set first timer threshold t1_th (step 112).

  When the actual current value Im is less than the predetermined current value I_th (step 109: NO) and when the duty ratio α is less than the predetermined duty ratio α_th (step 110: NO), that is, sufficient drive power for the motor 41 Is not supplied, the timer value t1 of the first timer is cleared (step 113). Even when the target rotation speed N * is less than the predetermined positive rotation speed N_p (step 106: NO), the routine proceeds to step 113 and the timer value t1 of the first timer is cleared.

  When the timer value t1 is larger than the first timer threshold value t1_th (step 112: YES), the microcomputer 71 determines whether or not the counter value C of the retry counter is equal to or less than the predetermined counter value C_th indicating the predetermined number of times. Is determined (step 114). Subsequently, when the counter value C is equal to or smaller than the predetermined counter value C_th (step 114: YES), the counter value C is incremented (step 115), and reverse rotation control is executed (step 116). On the other hand, when the counter value C is larger than the predetermined counter value C_th (step 114: NO), energization to the motor 41 is stopped (step 117). If the timer value t1 is equal to or smaller than the first timer threshold value t1_th (step 112: NO), the processing of steps 114 to 116 is not executed, and the routine proceeds to step 102.

Next, a processing procedure for reverse rotation control by the microcomputer will be described.
As shown in FIG. 4, the microcomputer 71 first sets the target rotational speed N * to a predetermined first reverse rotational speed N_g1 (step 201), and clears the timer value t2 of the second timer provided in the microcomputer 71. (Step 202). Subsequently, the second timer threshold value t2_th of the second timer is set to the first measurement time t_g1 indicating the first reverse rotation time (step 203), and the completion flag F_co indicating that the execution of the reverse rotation control is completed is turned off. A state is set (step 204).

  Subsequently, the microcomputer 71 determines whether or not the timer value t2 of the second timer is greater than or equal to the second timer threshold value t2_th (step 205). If the timer value t2 is less than the second timer threshold value t2_th (step 205: NO), the motor 41 is driven so that the actual rotational speed N rotates backward at the target rotational speed N * (step 206). The timer value t2 of the second timer is incremented (step 207). That is, until the timer value t2 exceeds the first measurement time t_g1, in step 206, the motor 41 is reversely rotated so that the predetermined first reverse rotation speed N_g1 is obtained.

  On the other hand, when the timer value t2 of the second timer is greater than or equal to the second timer threshold value t2_th (step 205: YES), the microcomputer 71 determines whether or not the completion flag F_co is in an off state (step 208). . When the completion flag F_co is in the off state and the execution of the reverse rotation control is not completed (step 208: YES), the actual current value Im is acquired from the current sensor 76 (step 209), and the actual current value is obtained. It is determined whether Im is equal to or higher than the high load determination value I_hi (step 210). Subsequently, when the actual current value Im is equal to or higher than the high load determination value I_hi (step 210: YES), the second timer threshold t2_th of the second timer is set to the second counter rotation time at the first measurement time t_g1. A second measurement time t_g2 including the indicated time is set (step 211), and the target rotation speed N * is set to a predetermined second reverse rotation speed N_g2 (step 212). Then, the completion flag F_co is turned on (step 213), and the process proceeds to step 205. That is, when the timer value t2 is equal to or greater than the first measurement time t_g1 and less than the second measurement time t_g2, the motor 41 is reversely rotated so that the predetermined second reverse rotation speed N_g2 is obtained.

  The microcomputer 71 performs reverse rotation control when the completion flag F_co is on (step 208: NO) and when the actual current value Im is less than the high load determination value I_hi (step 210: NO). The process ends, and the flow returns to the flow shown in FIG.

Next, the operation of this embodiment will be described.
Consider a case where the IG is turned on while the driver further cuts the steering wheel 2 from the state where the driver is at the steering end when the oil temperature of the hydraulic oil is extremely low. At this time, the driving power is supplied to the electric pump 22 when the IG is turned on. However, since the load for rotating the motor 41 in the forward direction becomes excessive, the actual rotational speed N becomes less than the lower limit rotational speed N_lo. Then, when this state continues for a predetermined determination time, reverse rotation control is executed. Here, when the motor 41 is rotated in the reverse direction as described above, the load is lower than when the motor 41 is rotated in the forward direction. Therefore, the motor 41 rotates at a high rotation speed, and a lot of friction is generated by the pump 42 and the like. Heat is generated. As a result, the oil temperature of the hydraulic oil rises, so that the load on the motor 41 is quickly reduced, and when the forward rotation control is executed again, a quick assist force can be applied. That is, a decrease in responsiveness is suppressed.

Next, the effect of this embodiment will be described.
(1) When the oil temperature of the hydraulic oil is extremely low, when the driver turns on the IG while further turning the steering wheel 2 from the steering end, the reverse rotation control is executed, so that the oil temperature is as described above. And the load for rotating the motor 41 forward can be reduced. That is, the situation in which the load for rotating the motor 41 in the forward direction is improved and the hydraulic oil can be appropriately supplied to the hydraulic cylinder 21, so that the steering feeling can be prevented from being lowered.

  (2) The microcomputer 71 allows the reverse rotation control to be executed only when the motor 41 is started. Here, when the IG is turned on, the situation in which the steering wheel 2 is further cut from the state at the steering end, for example, the vehicle cannot be taken out from the garage unless the vehicle is steered to the vicinity of the steering end. This is likely to occur in some cases and may occur repeatedly. Compared to this, the situation where the actual rotational speed N becomes less than the lower limit rotational speed N_lo after the start of the motor 41 is completed and the motor 41 rotates normally is unlikely to occur. And since execution of reverse rotation control cannot provide an appropriate assist force, execution of reverse rotation control is not preferable from the viewpoint of improving reliability. Therefore, by allowing the reverse rotation control to be executed only when the motor 41 is started as in the present embodiment, it is possible to improve reliability while suppressing a decrease in responsiveness.

  (3) The microcomputer 71 determines whether or not the motor 41 is activated based on the atmospheric temperature TMP correlated with the oil temperature of the hydraulic oil, that is, whether or not the reverse rotation control is permitted. did. Therefore, in a state where the oil temperature of the hydraulic oil is high and the load for rotating the motor 41 in the forward direction is low, the reverse rotation control is not executed and the motor 41 is continuously rotated in the forward direction, so that the responsiveness is further improved. Can do.

  (4) When the reverse rotation control is executed, the microcomputer 71 determines that the load for reversely rotating the motor 41 is high based on the actual current value Im after the reverse rotation of the motor 41 continues for the first reverse rotation time. In this case, the motor 41 is further rotated in reverse for the second reverse rotation time. Therefore, if the motor load is high after the motor 41 has been reversely rotated continuously for the first predetermined time, that is, if the hydraulic oil temperature is still low and its viscosity is estimated to be high, the motor 41 is further reversed. Since it rotates, the oil temperature of hydraulic fluid can be raised quickly.

(5) Since the predetermined second reverse rotation speed N_g2 is set larger than the predetermined first reverse rotation speed N_g1, the oil temperature of the hydraulic oil can be increased more quickly.
(6) When the actual current value Im is less than the predetermined current value I_th, or when the duty ratio α is less than the predetermined duty ratio α_th, that is, the microcomputer 71 does not supply sufficient drive power to the motor 41. Execution of reverse rotation control was prohibited. Therefore, the reverse rotation control can be executed by accurately determining the situation where the actual rotation speed N is less than the lower limit rotation speed N_lo due to a high load for rotating the motor 41 in the forward direction.

  (7) The microcomputer 71 stops the motor 41 when the number of executions of the reverse rotation control exceeds a predetermined number. Here, if the actual rotational speed N does not exceed the lower limit rotational speed N_lo even if the reverse rotational control is executed a plurality of times, it is estimated that an abnormality that cannot be improved by causing the electric pump 22 to reversely rotate the motor 41 has occurred. it can. Therefore, by stopping the motor 41 in such a case, it is possible to suppress, for example, wasteful power consumption.

(Second Embodiment)
Next, a second embodiment of the control device for the hydraulic power steering device will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The microcomputer 71 according to the present embodiment allows the reverse rotation control to be executed not only at the time of startup but also after the actual rotational speed N becomes equal to or higher than the lower limit rotational speed N_lo. Specifically, the microcomputer 71 sets the actual rotational speed N to the lower limit rotational speed N_lo, even though the target rotational speed N * is higher than the predetermined positive rotational speed N_p and sufficient drive power is supplied to the motor 41. The reverse rotation control is temporarily executed when the state of less than the predetermined determination time continues.

  That is, as shown in FIG. 5, when the microcomputer 71 of the present embodiment executes the forward rotation control (step 103), the microcomputer 71 shifts to step 106 to check whether the target rotational speed N * is greater than the predetermined positive rotational speed N_p. Determine whether or not. That is, the microcomputer 71 executes the same processing as in the first embodiment except that the processing in steps 104, 105, and 108 in the first embodiment is not executed.

Next, the operation of this embodiment will be described.
For example, when foreign matter such as pebbles is caught in the pump 42, the load for rotating the motor 41 forward becomes excessive, and the state where the actual rotational speed N of the motor 41 is less than the lower limit rotational speed N_lo continues for a predetermined determination time. Reverse rotation control is executed. As a result, if the foreign matter is released and the foreign matter is discharged from the pump 42, an appropriate assist force can be applied when the forward rotation control is executed again. In addition, when the oil temperature of the hydraulic oil is extremely low, even when the driver turns on the IG while further turning the steering wheel 2 from the steering end, the assist force is quickly applied as in the first embodiment. It becomes possible to do.

As described above, according to the present embodiment, in addition to the effects (1) and (4) to (7) of the first embodiment, the following effects can be achieved.
(8) When foreign matter such as pebbles is caught in the pump 42, the load for causing the foreign matter to be discharged and rotating the motor 41 in the forward direction can be reduced by executing reverse rotation control. That is, the situation in which the load for rotating the motor 41 in the forward direction is improved and the hydraulic oil can be appropriately supplied to the hydraulic cylinder 21, so that the steering feeling can be prevented from being lowered.

In addition, each said embodiment can also be implemented in the following aspects which changed this suitably.
In the first embodiment, it is determined whether or not the oil temperature is extremely low based on the ambient temperature TMP in the electric pump 22, but this is not a limitation, and for example, a temperature sensor that directly detects the oil temperature of the hydraulic oil is provided. It is also possible to determine whether or not the oil temperature is extremely low based on a value detected by this sensor.

-In the said 1st Embodiment, it is not necessary to determine whether it is at the time of starting of the motor 41 based on the oil temperature of hydraulic fluid.
In each of the above embodiments, it is determined whether sufficient drive power is supplied to the motor 41 based on both the actual current value Im and the duty ratio α. However, the present invention is not limited to this, and the actual current value Im and the duty are determined. It may be determined whether sufficient drive power is supplied to the motor 41 based on one of the ratios α. Further, whether or not sufficient drive power is supplied to the motor 41 may be determined at any time before the timer value t1 of the first timer in step 111 is incremented. It is not necessary to determine whether or not sufficient drive power is supplied to the motor 41.

  In each of the above embodiments, when the reverse rotation control is executed, the second reverse rotation is further performed when the load for rotating the motor 41 reversely is high after the motor 41 is reversely rotated continuously for the first reverse rotation time. The motor 41 was reversely rotated for the duration. However, the present invention is not limited to this, and the reverse rotation control may be ended regardless of the load of the motor 41 after the motor 41 is reversely rotated continuously for the first reverse rotation time. Further, the predetermined second reverse rotation speed N_g2 may be a value equal to or lower than the predetermined first reverse rotation speed N_g1.

  In each of the above embodiments, the reverse rotation control is repeatedly executed. However, the present invention is not limited to this. If the actual rotation speed N of the motor 41 does not increase normally after the reverse rotation control is executed only once, the motor 41 may be stopped.

  In the first embodiment, the target rotational speed N * is higher than the predetermined positive rotational speed N_p and sufficient drive power is supplied to the motor 41 when the oil temperature of the hydraulic oil is extremely low. Regardless, when the actual rotation speed N is less than the lower limit rotation speed N_lo, the reverse rotation control may be executed without waiting for the elapse of a predetermined determination time. Similarly, in the second embodiment, the reverse rotation control may be executed without waiting for the elapse of a predetermined determination time.

  In each of the above embodiments, a brushed DC motor is used as the motor 41. However, the present invention is not limited to this, and for example, a brushless motor may be used. Further, as the pump 42, for example, a vane pump or the like may be used.

  In each of the above embodiments, the hydraulic power steering device 1 is configured to include only one electric pump 22 as a hydraulic source of the hydraulic cylinder 21, but may be configured to include a plurality of electric pumps.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic power steering apparatus, 21 ... Hydraulic cylinder, 22 ... Electric pump, 24 ... Switching valve, 25 ... Storage tank, 41 ... Motor, 42 ... Pump, 43 ... ECU, 71 ... Microcomputer, 72 ... Drive circuit, 78 ... Temperature sensor, F_co: completion flag, F_su: start flag, Im: actual current value, N: actual rotation speed, N *: target rotation speed, TMP: ambient temperature, α: duty ratio.

Claims (8)

In a control device for a hydraulic power steering device that generates an assist force by supplying hydraulic oil to a hydraulic actuator using an electric pump,
The electric pump supplies hydraulic oil to the hydraulic actuator by rotating a motor serving as a drive source in one direction.
If the actual rotational speed of the motor does not rise normally in accordance with the target rotational speed of the motor, temporarily performs reverse rotation control to reversely rotate the motor in the other direction opposite to the one direction. A control device for a hydraulic power steering device. In the control device of the hydraulic power steering device according to claim 1,
A control device for a hydraulic power steering device, wherein execution of the reverse rotation control is allowed only when the motor is started. In the control apparatus of the hydraulic power steering apparatus according to claim 2,
A control device for a hydraulic power steering device, wherein it is determined whether or not the motor is activated based on an oil temperature of the hydraulic oil. In the control apparatus of the hydraulic power steering device according to any one of claims 1 to 3,
In the reverse rotation control, when the load for reversely rotating the motor after the reverse rotation of the motor continues for the first reverse rotation time is high, the motor is reversely rotated for the second reverse rotation time. A control device for a hydraulic power steering device. In the control device of the hydraulic power steering device according to claim 4,
The target rotational speed when the motor is further reversely rotated after the first reverse rotation time is continued and the motor is reversely rotated is the target rotation when the motor is reversely rotated for the first reverse rotation time. A control device for a hydraulic power steering device, wherein the control device is set higher than the number. In the control apparatus of the hydraulic power steering device according to any one of claims 1 to 5,
The control device for a hydraulic power steering device, wherein execution of the reverse rotation control is prohibited when an actual current value of the electric pump is less than a predetermined current value corresponding to a target rotational speed. In the control apparatus of the hydraulic power steering apparatus according to any one of claims 1 to 6,
The drive circuit for supplying drive power to the motor is constituted by a switching element that is turned on / off based on a duty ratio of a pulse signal that is subjected to pulse width modulation control,
When the duty ratio is less than a predetermined duty ratio corresponding to the target rotational speed, the control device for the hydraulic power steering apparatus is prohibited from executing the reverse rotation control. In the control apparatus of the hydraulic power steering device according to any one of claims 1 to 7,
The control device for a hydraulic power steering apparatus, wherein the motor is stopped when the number of executions of the reverse rotation control exceeds a predetermined number.