JP2014210496A - Control device for hydraulic power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a hydraulic power steering device that can suppress excessive current consumption while having a plurality of electric pumps.SOLUTION: In a high load state where either one of a first current value Im1 flowing in a first motor 41 or a second current value Im2 flowing in a second motor 44 is equal to or larger than an upper limit current value or in a low assist state where target rotational frequency is less than a low rotation threshold value, first and second microcomputers 71, 73 activate either one of a first or second electric pump 22, 23, and stop the other. The first and second microcomputers 71, 73 determine the electric pump to be activated and the electric pump to be stopped in the high load state or the low assist state on the basis of on/off states of first and second instruction flags Fi1, Fi2 stored in non-volatile memories 71a, 73a, and alternately activate (stop) the first electric pump 22 and the second electric pump 23 in the state.

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 apparatus that uses a plurality of electric pumps that generate hydraulic pressure by driving a motor as a hydraulic source of a hydraulic actuator. In such a hydraulic power steering device, normally, even when the steering operation is not performed, at least one electric pump is operated at a relatively low rotational speed (standby rotational speed), thereby providing a quick assist force. The responsiveness is improved as possible.

JP-A-9-95251

  By the way, since the load of the motor becomes high at the time of steering such as stationary, for example, the current flowing through the motor (electric pump) becomes large. On the other hand, since the capacity of the on-vehicle power source mounted on the vehicle is determined, in the configuration including a plurality of electric pumps as described in Patent Document 1, current consumption may be excessive when the motor load is high. There was still room for improvement in this regard.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a control device for a hydraulic power steering device that includes a plurality of electric pumps and can suppress an excessive current consumption. Is to provide.

  A control device for a hydraulic power steering apparatus that solves the above-described problem includes a plurality of electric pumps for supplying hydraulic oil to a hydraulic actuator that generates assist force, and includes at least a motor that is a drive source of each electric pump. When the current value flowing in one is equal to or greater than a predetermined upper limit current value indicating that the load on the motor is high, one of the electric pumps is operated and the other electric pump is The gist is to sequentially switch between the one electric pump and the other electric pump.

  According to the above configuration, when the load on the motor is high, hydraulic oil is supplied to the hydraulic actuator by only one electric pump, so that it is possible to suppress an excessive amount of current consumed by the hydraulic power steering device. . In the above configuration, since one electric pump that operates when the motor load is high and another electric pump that stops are sequentially switched, one of the plurality of electric pumps deteriorates faster than the other. This can be suppressed and the life of the hydraulic power steering apparatus can be extended.

  In the control device for the hydraulic power steering device, when the target rotational speed of the motor is less than a predetermined low rotation threshold value indicating that the required flow rate of hydraulic fluid is small, one of the electric pumps is selected. While actuating the electric pump and stopping the other electric pump, it is preferable to sequentially switch between the one electric pump and the other electric pump.

  According to the above configuration, since one electric pump that operates when the target rotational speed of the motor is low and another electric pump that stops are sequentially switched, one of the plurality of electric pumps is faster than the other. Deterioration can be further suppressed, and the life of the hydraulic power steering apparatus can be further extended.

  In the control device for the hydraulic power steering apparatus, an instruction flag provided for each electric pump and indicating whether or not the electric pump should be operated as the one electric pump, and a nonvolatile storage for storing a state of the instruction flag A memory, and determining the one electric pump and the other electric pump based on the state of each instruction flag.

  According to the above configuration, since the state of the instruction flag is stored in the non-volatile memory, the state is maintained even after the ignition switch (IG) is turned off. Therefore, it is possible to appropriately switch between one electric pump and another electric pump before and after the IG is turned off.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress that the consumption of electric current becomes excessive, lifetime can be achieved.

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 a 1st electric pump. The flowchart which shows the procedure of a 1st operation | movement determination process. The flowchart which shows the procedure of a 1st instruction flag inversion process. The flowchart which shows the control procedure of a 2nd electric pump. The flowchart which shows the procedure of a 2nd action | operation determination process. The flowchart which shows the procedure of a 2nd instruction flag inversion process.

Hereinafter, an embodiment of a control device for 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 cylindrical rack housing 6 that is movably inserted. 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 also includes a hydraulic cylinder 21 as a hydraulic actuator that generates an assist force that assists the steering operation, and first and second electric pumps 22 and 23 that supply hydraulic oil to the hydraulic cylinder 21. ing. In addition, the hydraulic power steering device 1 stores hydraulic oil supplied to and discharged from the hydraulic cylinder 21 by the switching valve 24 that controls supply and discharge of hydraulic oil to the hydraulic cylinder 21 and the first and second electric pumps 22 and 23. The storage tank 25 is provided.

  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.

  As shown in FIG. 2, the first electric pump 22 includes a first motor 41 as a driving source, a first pump 42 that generates hydraulic pressure by being driven by the first motor 41, and an operation of the first motor 41. And a first ECU 43 for controlling the control. The second electric pump 23 includes a second motor 44 serving as a drive source, a second pump 45 that generates hydraulic pressure when driven by the second motor 44, and a second ECU 46 that controls the operation of the second motor 44. And. That is, in the present embodiment, the first and second ECUs 43 and 46 constitute a control device. As shown in FIG. 1, each suction port (not shown) of the first and second electric pumps 22 and 23 is connected to the storage tank 25 via a suction oil passage 47.

  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 the discharge ports (not shown) of the first and second electric pumps 22 and 23 via a supply oil passage 55 that is bifurcated on one end side. 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 first and second electric pumps 22 and 23 is supplied to the switching valve 24 through the supply oil passage 55. Then, the hydraulic oil supplied to the switching valve 24 is supplied to the first and second hydraulic chambers 32, via one of the first and second oil supply / discharge oil passages 57, 58 according to the steering operation of the driver. One of 33 is supplied. 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. .

Next, the electrical configuration of the hydraulic power steering apparatus will be described.
As shown in FIGS. 1 and 2, the first and second electric pumps 22 and 23 are connected to each other via a CAN (in-vehicle network) 61. A steering sensor 62 and a vehicle speed sensor 63 are connected to the CAN 61, and the steering angle θs and the vehicle speed SPD of the steering wheel 2 are transmitted. Then, the first and second ECUs 43 and 46 operate the first and second electric pumps 22 and 23 (first and second motors 41 and 44) in cooperation with each other based on each state quantity obtained via the CAN 61. To control.

  Specifically, as shown in FIG. 2, the first ECU 43 includes a first microcomputer 71 that outputs a motor control signal, and a first drive circuit 72 that supplies drive power to the first motor 41 based on the motor control signal. It has. The second ECU 46 includes a second microcomputer 73 that outputs a motor control signal, and a second drive circuit 74 that supplies drive power to the second motor 44 based on the motor control signal. The first and second drive circuits 72 and 74 are respectively connected to the same on-vehicle power source (battery) 75 mounted on the vehicle.

  The first and second drive circuits 72 and 74 include a known PWM inverter in which a pair of switching elements (for example, FETs) connected in series is a basic unit (switching arm) and these are connected in parallel. The motor control signal is used to define the on / off state (on-duty ratio) of each switching element. Then, the first and second drive circuits 72 and 74 supply drive power based on the on-duty ratio and the voltage of the in-vehicle power supply 75 indicated by the input motor control signal to the first and second motors 41 and 44, respectively. .

  The first microcomputer 71 includes a first current sensor 76 for detecting a first current value Im1 indicating a current value flowing through the first motor 41 (first electric pump 22), and a first angle indicating the rotation angle of the first motor 41. A first rotation angle sensor 77 for detecting the rotation angle θm1 is connected. The first microcomputer 71 is provided with a nonvolatile memory 71a. On the other hand, the second microcomputer 73 indicates the rotation angle of the second motor 44 and the second current sensor 78 for detecting the second current value Im2 indicating the current value flowing through the second motor 44 (second electric pump 23). A second rotation angle sensor 79 for detecting the second rotation angle θm2 is connected. The second microcomputer 73 is provided with a non-volatile memory 73a. The first and second microcomputers 71 and 73 detect each state quantity from each sensor at a predetermined sampling period and receive each state quantity from the CAN 61. The first and second current values Im1 and Im2 are transmitted from the first and second microcomputers 71 and 73 to the CAN 61, respectively. Then, the first and second microcomputers 71 and 73 control the operation of the first and second motors 41 and 44 through the supply of driving power by outputting motor control signals based on the acquired respective state quantities. To do.

  More specifically, the first microcomputer 71 calculates a first rotational speed N1 indicating the actual rotational speed (rotational speed) of the first motor 41 (first pump 42) based on the steering angle θs and the vehicle speed SPD. By executing the rotation speed control (speed feedback control) so that the target rotation speed N * is reached, a motor control signal is output to control the operation of the first motor 41. The first rotational speed N1 is obtained by differentiating the first rotational angle θm1. Further, a relatively low standby rotational speed is set in advance as the minimum value for the target rotational speed N *. The target rotational speed N * is calculated so as to be higher than the standby rotational speed in accordance with the steering speed ωs and the vehicle speed SPD obtained by differentiating the steering angle θs. Specifically, the first microcomputer 71 calculates a higher target rotational speed N * as the absolute value of the steering speed ωs is larger and as the vehicle speed SPD is lower.

  Similarly, in the second microcomputer 73, the second rotational speed N2 indicating the rotational speed of the second motor 44 (second pump 45) becomes the target rotational speed N * calculated based on the steering angle θs and the vehicle speed SPD. Thus, by executing the rotational speed control, the motor control signal is output to control the operation of the second motor 44. The second rotational speed N2 is obtained by differentiating the second rotational angle θm2, and the second microcomputer 73 of the present embodiment is similar to the first microcomputer 71 (the same value) as the target rotational speed N *. Is calculated. Then, motor control signals are output from the first and second microcomputers 71 and 73 to the first and second drive circuits 72 and 74, respectively, and drive power based on the motor control signals is supplied to the first and second motors 41 and 44, respectively. As a result, the first and second pumps 42 and 45 are operated. 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.

  Note that the first microcomputer 71 of the present embodiment performs abnormality determination of the first motor 41 based on the first current value Im1, the first rotation angle θm1, and the like. Then, the first microcomputer 71 transmits a first abnormality determination signal S_f1 indicating the result of the abnormality determination to the CAN 61. When an abnormality is detected, the first microcomputer 71 stops supplying the driving power and stops the first motor 41. Let As a method for determining such an abnormality, for example, when the first current value Im1 becomes a value that cannot be obtained, or when the first rotation angle θm1 does not change even though the drive power is supplied, the abnormality is determined to be abnormal. Various methods such as determination can be employed. Similarly, the second microcomputer 73 of the present embodiment performs abnormality determination of the second motor 44 based on the second current value Im2, the second rotation angle θm2, and the like, and a second abnormality determination signal S_f2 indicating the result of the abnormality determination. Is transmitted to the CAN 61, and the supply of driving power is stopped to stop the second motor 44.

  Here, for example, at the time of steering such as stationary driving or when the temperature of the hydraulic oil is low, the load on the first and second motors 41 and 44 increases, so that the current flowing through the first and second motors 41 and 44 is increased. growing. On the other hand, since the capacity of the in-vehicle power supply 75 is determined, in the hydraulic power steering apparatus 1 provided with the first and second electric pumps 22 and 23 as in the present embodiment, the first and second motors 41, When 44 is in a high load state, current consumption may be excessive. Further, in a low assist state where the flow rate of hydraulic oil that can be supplied to the hydraulic cylinder 21 may be small, such as during non-steering or during slight steering, for example, both the first and second electric pumps 22 and 23 are set at the standby rotation speed. There is little need to keep it operating, which can hinder power saving.

  In view of this point, the first and second microcomputers 71 and 73 of the present embodiment are configured such that one of the first current value Im1 flowing through the first motor 41 and the second current value Im2 flowing through the second motor 44 is the upper limit current. When the value is equal to or greater than the value I_th (high load state), one of the first and second electric pumps 22 and 23 is operated and the other is stopped. Further, the first and second microcomputers 71 and 73 turn off one of the first and second electric pumps 22 and 23 when the target rotation speed N * is less than the low rotation threshold N_lo (low assist state). Operate and stop the other. Then, the first and second microcomputers 71 and 73 sequentially switch between the electric pump (one electric pump) operated in the high load state or the low assist state and the electric pump (other electric pump) to be stopped in the same state. The first electric pump 22 and the second electric pump 23 are alternately operated (stopped). On the other hand, when the first and second microcomputers 71 and 73 both have the first and second current values Im1 and Im2 less than the upper limit current value I_th and the target rotational speed N * is equal to or higher than a predetermined low rotational threshold N_lo. In this case, both the first and second electric pumps 22 and 23 are operated.

  Note that the upper limit current value I_th is that the load on the first and second motors 41 and 44 is high, and the amount of current consumed by the hydraulic power steering device 1 when the current flows through the first and second motors 41 and 44 is excessive. For example, the value is set to about 100A. The low rotation threshold N_lo is a value indicating that the steering operation is hardly performed and the required flow rate of the hydraulic oil is small, and is set to about 2000 rpm, for example.

  More specifically, the first microcomputer 71 sets the target rotational speed N in a state where the first electric current value Im1 is not limited in a state where the second electric pump 23 is stopped (a state where no driving power is supplied). The operation of the first motor 41 is controlled so that the first rotational speed N1 follows * (normal rotational speed control). On the other hand, in a state where the second electric pump 23 is operating (a state where driving power is supplied), the first microcomputer 71 is in a state where the first current value Im1 is limited to a predetermined limit value I_lim or less. The operation of the first motor 41 is controlled so that the first rotational speed N1 follows the target rotational speed N * (rotational speed control with current limitation). In addition, when the first microcomputer 71 cannot receive each state quantity due to an abnormality in the CAN 61, the first microcomputer 71 limits the first current value Im1 flowing through the first motor 41 to a limit value I_lim or less, and sets a preset alternative target. The operation of the first motor 41 is controlled so that the first rotational speed N1 follows the rotational speed (alternative rotational speed control).

  The limit value I_lim is set to a value (for example, about 75 A) that can be stably and simultaneously supplied from the in-vehicle power supply 75 to the first and second electric pumps 22 and 23. Further, in the rotational speed control with current limitation, even if the deviation between the target rotational speed N * and the first rotational speed N1 is large, if the first current value Im1 approaches the limit value I_lim, it is indicated in the motor control signal. By limiting the ON duty ratio to be small, the first current value Im1 is prevented from exceeding the limit value I_lim.

  Similarly, the second microcomputer 73 performs normal rotation speed control when the first electric pump 22 is stopped, and rotates with current limitation when the first electric pump 22 is operating. When the control is executed and each state quantity cannot be received due to the abnormality of the CAN 61, the alternative rotational speed control is executed.

  A memory 71a provided in the first microcomputer 71 has a first instruction flag Fi1 indicating whether or not the first electric pump 22 should be operated in a high load state or a low assist state (should be one electric pump). The on / off state is stored. On the other hand, the memory 73a provided in the second microcomputer 73 stores an on / off state of a second instruction flag Fi2 indicating whether or not the second electric pump 23 should be operated in a high load state or a low assist state. The on / off states of the first and second instruction flags Fi1 and Fi2 are changed from the high load state or the low assist state in which only one of the first and second electric pumps 22 and 23 is operated to the first and second electric pumps. When both 22 and 23 are activated, they are inverted by the first and second microcomputers 71 and 73, respectively. The first and second microcomputers 71 and 73 transmit the respective states of the first and second instruction flags Fi1 and Fi2 to the CAN 61, and recognize these states via the CAN 61. Then, the first and second microcomputers 71 and 73 determine whether or not to operate (stop) the first and second electric pumps 22 and 23, respectively, based on the states of the first and second instruction flags Fi1 and Fi2. Thus, the first electric pump 22 and the second electric pump 23 are operated alternately.

  Specifically, when the first instruction flag Fi1 is on and the second instruction flag Fi2 is off, the first microcomputer 71 operates the first electric pump 22, and the second microcomputer 73 The second electric pump 23 is stopped. On the other hand, when the first instruction flag Fi1 is in the off state and the second instruction flag Fi2 is in the on state, the first microcomputer 71 stops the first electric pump 22 and the second microcomputer 73 stops the second electric pump. 23 is activated.

  Note that the state of the first instruction flag Fi1 and the state of the second instruction flag Fi2 are normally opposite to each other by the initial setting, but the first instruction flag Fi1 is stored in the memories 71a and 73a, for example, due to the influence of noise or the like. There is a possibility that the on / off states of the first and second instruction flags Fi1, Fi2 are reversed. In consideration of this point, when both the first and second instruction flags Fi1 and Fi2 are on, the first microcomputer 71 operates the first electric pump 22, and the second microcomputer 73 operates as the second electric pump. 23 is stopped. When both the first and second instruction flags Fi1 and Fi2 are off, the first microcomputer 71 stops the first electric pump 22, and the second microcomputer 73 operates the second electric pump 23. .

Next, the control procedure of the first electric pump by the first microcomputer will be described.
As shown in FIG. 3, when the first microcomputer 71 is in a state where each state quantity can be received from the CAN 61 after the ignition switch (IG) is turned on (step 101: YES), the steering angle The state of θs, vehicle speed SPD, second current value Im2, second abnormality determination signal S_f2, and second instruction flag Fi2 is received from CAN 61 (step 102). In addition, when each state quantity cannot be received from CAN61 (step 101: NO), alternative rotation speed control is performed (step 103).

  Subsequently, the first microcomputer 71 transmits the first current value Im1 input from the first current sensor 76 to the CAN 61 (step 104), and transmits the state of the first instruction flag Fi1 stored in the memory 71a to the CAN 61. (Step 105). Further, abnormality determination of the first motor 41 is performed (step 106), and a first abnormality determination signal S_f1 indicating the result of abnormality determination of the first motor is transmitted to the CAN 61 (step 107). If the first abnormality determination signal S_f1 is on and the first motor 41 is abnormal (step 108: NO), the supply of drive power to the first motor 41 is stopped and the first motor 41 is stopped. Is stopped (step 109).

  On the other hand, when the first abnormality determination signal S_f1 is off and the first motor 41 is normal (step 108: YES), the first microcomputer 71 sets the target rotational speed based on the steering speed ωs and the vehicle speed SPD. Calculate (step 110). Subsequently, when one of the first and second current values Im1 and Im2 is equal to or higher than the upper limit current value I_th, or when the target rotation speed N * is less than the low rotation threshold N_lo (step 111: NO). Based on the first and second instruction flags Fi1, Fi2, a first drive determination process described later is performed (step 112). As a result of the first drive determination process, the first operation determination flag Fd1 indicating whether or not the first electric pump 22 is actually operated (stopped) is in the on state, and the first motor 41 is operated in the order of operation. If there is (step 113: YES), normal rotation speed control is performed (step 114). On the other hand, when the first operation determination flag Fd1 is in the off state and the order in which the first motor 41 is operated (step 113: NO), the process proceeds to step 109 and the first motor 41 is stopped.

  On the other hand, the first microcomputer 71 determines that the first and second current values Im1 and Im2 are less than the upper limit current value I_th and the target rotation speed N * is equal to or higher than the low rotation threshold N_lo (step 111). : YES), first instruction flag inversion processing described later is performed (step 115). Subsequently, it is determined whether or not the second motor 44 is normal based on the second abnormality determination signal S_f2 (step 116). When the second abnormality determination signal S_f2 is in the off state and the second motor 44 is normal (step 116: YES), the rotational speed control with current limitation is executed (step 117). If the second abnormality determination signal S_f2 is in the on state and the second motor 44 is abnormal (step 117: NO), the routine proceeds to step 115 and normal rotation speed control is executed.

Next, the procedure of the first operation determination process by the first microcomputer will be described.
As shown in FIG. 4, when the first instruction flag Fi1 is on and the second instruction flag Fi2 is off (step 201: YES), the first microcomputer 71 determines the first operation determination flag. Fd1 is turned on (step 202). Thereby, the first electric pump 22 operates when the high load state or the low assist state is reached. Then, the first inversion permission flag Fp1 for permitting the execution of the first instruction flag inversion process is turned on (step 203), and the flow returns to the flow shown in FIG.

  On the other hand, when the first instruction flag Fi1 is not on or when the second instruction flag Fi2 is not off (step 201: NO), both the first and second instruction flags Fi1 and Fi2 are off. Whether or not (step 204). When both the first and second instruction flags Fi1 and Fi2 are in the off state (step 204: YES), the process proceeds to step 202 and the first operation determination flag Fd1 is turned on. Thereafter, the process proceeds to step 203, where the first inversion permission flag Fp1 is turned on, and the flow returns to the flow shown in FIG.

  On the other hand, when one of the first and second instruction flags Fi1 and Fi2 is on (step 204: NO), the first microcomputer 71 sets the first operation determination flag Fd1 to the off state (step 204: NO). Step 205). In other words, when the first instruction flag Fi1 is off and the second instruction flag Fi2 is on, or when both the first and second instruction flags Fi1 and Fi2 are on, The first operation determination flag Fd1 is turned off. Thereby, the first electric pump 22 stops when a high load state or a low assist state is established. Thereafter, the process proceeds to step 203, where the first inversion permission flag Fp1 is turned on, and the flow returns to the flow shown in FIG.

Next, the procedure of the first instruction flag inversion process by the first microcomputer will be described.
As shown in FIG. 5, the first microcomputer 71 is in the case where the first inversion permission flag Fp1 is in the on state and the execution of the inversion processing of the first instruction flag Fi1 is permitted (step 301: YES). Determines whether or not the first instruction flag Fi1 is on (step 302). If the first instruction flag Fi1 is on (302: YES), the first instruction flag Fi1 is turned off (step 303), and the state of the first instruction flag Fi1 is stored in the memory 71a ( Step 304). Thereafter, the first inversion permission flag Fp1 is turned off (step 305), and the flow returns to the flow shown in FIG.

  On the other hand, when the first instruction flag Fi1 is in the off state (302: NO), the first instruction flag Fi1 is turned on (step 306), the process proceeds to step 304, and the state of the first instruction flag Fi1 is stored in the memory. Store in 71a. Thereafter, the process proceeds to step 305, the first inversion permission flag Fp1 is turned off, and the process returns to the flow shown in FIG. If the first inversion permission flag Fp1 is in the off state and the inversion process of the first instruction flag Fi1 is not permitted (step 301: NO), the processes in steps 302 to 306 are not executed. .

Next, the control procedure of the second electric pump by the second microcomputer will be described.
As shown in FIG. 6, when the second microcomputer 73 is in a state where each state quantity can be received from the CAN 61 after the IG is turned on (step 401: YES), the steering angle θs, the vehicle speed SPD. The state of the first current value Im1, the first abnormality determination signal S_f1, and the first instruction flag Fi1 is received from the CAN 61 (step 402). In addition, when each state quantity cannot be received from CAN61 (step 401: NO), alternative rotational speed control is performed (step 403).

  Subsequently, the second microcomputer 73 transmits the second current value Im2 input from the second current sensor 78 to the CAN 61 (step 404), and transmits the state of the second instruction flag Fi2 stored in the memory 73a to the CAN 61. (Step 405). Further, the abnormality determination of the second motor 44 is performed (step 406), and the second abnormality determination signal S_f2 indicating the result of the abnormality determination of the second motor 44 is transmitted to the CAN 61 (step 407). If the second abnormality determination signal S_f2 is on and the second motor 44 is abnormal (step 408: NO), the supply of drive power to the second motor 44 is stopped and the second motor 44 is stopped. Is stopped (step 409).

  On the other hand, when the second abnormality determination signal S_f2 is off and the second motor 44 is normal (step 408: YES), the second microcomputer 73 sets the target rotational speed based on the steering speed ωs and the vehicle speed SPD. Calculate (step 410). Subsequently, when one of the first and second current values Im1 and Im2 is equal to or higher than the upper limit current value I_th, or when the target rotational speed N * is less than the low rotational threshold N_lo (step 411: NO). Based on the first and second instruction flags Fi1, Fi2, a second operation determination process described later is performed (step 412). As a result of the second operation determination process, the second operation determination flag Fd2 indicating whether or not the second electric pump 23 is actually operated (stopped) is in the on state, and the second motor 44 is operated in the order of operation. If there is any (step 413: YES), normal rotational speed control is performed (step 414). On the other hand, when the second operation determination flag Fd2 is in the off state and the order in which the second motor 44 is operated (step 413: NO), the process proceeds to step 409 and the second motor 44 is stopped.

  On the other hand, the second microcomputer 73 determines that the first and second current values Im1 and Im2 are less than the upper limit current value I_th and the target rotation speed N * is equal to or higher than the low rotation threshold N_lo (step 411). : YES), second instruction flag inversion processing described later is performed (step 415). Subsequently, based on the first abnormality determination signal S_f1, it is determined whether or not the first motor 41 is normal (step 416). When the first abnormality determination signal S_f1 is in the off state and the first motor 41 is normal (step 416: YES), the rotational speed control with current limitation is executed (step 417). If the first abnormality determination signal S_f1 is in the on state and the first motor 41 is abnormal (step 416: NO), the process proceeds to step 415 and normal rotation speed control is executed.

Next, the procedure of the second operation determination process by the second microcomputer will be described.
As shown in FIG. 7, when the first instruction flag Fi1 is on and the second instruction flag Fi2 is off (step 501: YES), the second microcomputer 73 determines the second operation determination flag. Fd2 is turned off (step 502). Thereby, the second electric pump 23 stops when a high load state or a low assist state is entered. Then, the second inversion permission flag Fp2 for permitting execution of the second instruction flag inversion process is turned on (step 503), and the flow returns to the flow shown in FIG.

  On the other hand, when the first instruction flag Fi1 is not in the on state or when the second instruction flag Fi2 is not in the off state (step 501: NO), both the first and second instruction flags Fi1 and Fi2 are in the off state. It is determined whether or not (step 504). If both the first and second instruction flags Fi1 and Fi2 are off (step 504: YES), the process proceeds to step 502 and the second operation determination flag Fd2 is turned off. Thereafter, the process proceeds to step 503, where the second inversion permission flag Fp2 is turned on, and the flow returns to the flow shown in FIG.

  On the other hand, when one of the first and second instruction flags Fi1 and Fi2 is in the off state (step 504: NO), the second microcomputer 73 turns on the second operation determination flag Fd2 (step 504). Step 505). In other words, when the first instruction flag Fi1 is off and the second instruction flag Fi2 is on, or when both the first and second instruction flags Fi1 and Fi2 are on, The second operation determination flag Fd2 is turned on. As a result, the second electric pump 23 operates when a high load state or a low assist state is established. Thereafter, the process proceeds to step 503, where the second inversion permission flag Fp2 is turned on, and the flow returns to the flow shown in FIG.

Next, the procedure of the second instruction flag inversion process by the second microcomputer will be described.
As shown in FIG. 8, when the second inversion permission flag Fp2 is on and the second microcomputer 73 is permitted to execute the inversion processing of the second instruction flag Fi2 (step 601: YES), as shown in FIG. Determines whether the second instruction flag Fi2 is on (step 602). If the second instruction flag Fi2 is on (602: YES), the second instruction flag Fi2 is turned off (step 603), and the state of the second instruction flag Fi2 is stored in the memory 73a (step 603). Step 604). Thereafter, the second inversion permission flag Fp2 is turned off (step 605), and the flow returns to the flow shown in FIG.

  On the other hand, when the second instruction flag Fi2 is in the off state (602: NO), the second instruction flag Fi2 is turned on (step 606), the process proceeds to step 604, and the state of the second instruction flag Fi2 is stored in the memory. 73a is stored. Thereafter, the process proceeds to step 605, the second inversion permission flag Fp2 is turned off, and the flow returns to the flow shown in FIG. If the second inversion permission flag Fp2 is in the off state and the inversion process of the second instruction flag Fi2 is not permitted (step 601: NO), the processes of steps 602 to 606 are not executed. .

Next, the operation of this embodiment will be described.
For example, when the first instruction flag Fi1 is in the on state and the second instruction flag Fi2 is in the off state, the driver performs a stationary operation and the first and second motors 41 and 44 have high loads. Then, only the first electric pump 22 is operated, so that hydraulic oil is supplied to the hydraulic cylinder 21. Thereafter, for example, when the vehicle departs and the load of the first and second motors 41 and 44 is low, and the target rotational speed N * is equal to or higher than the low rotational threshold N_lo, the first and second electric pumps 22 and 23 are used. As a result, the hydraulic oil is supplied to the hydraulic cylinder 21. At this time, the first instruction flag Fi1 is switched to the off state, and the second instruction flag Fi2 is switched to the on state.

  Therefore, for example, when the driver does not steer greatly and enters a low assist state, the first electric pump 22 is stopped and only the second electric pump 23 is operated, so that hydraulic oil is supplied to the hydraulic cylinder 21. The Then, when the target rotational speed N * is equal to or higher than the low rotation threshold N_lo in a state where the loads of the first and second motors 41 and 44 are low, both the first and second electric pumps 22 and 23 are operated. The hydraulic oil is supplied to the hydraulic cylinder 21, and the states of the first and second instruction flags Fi1, Fi2 are switched again. As described above, in the hydraulic power steering apparatus 1 according to the present embodiment, the electric pumps operating in the high load state or the low assist state are alternately switched, so that the electric pump operating in the same state is suppressed from being biased to any one. The

Next, the effect of this embodiment will be described.
(1) When one of the first and second current values Im1 and Im2 is equal to or higher than the upper limit current value I_th, one of the first and second electric pumps 22 and 23 is activated and the other is stopped. Since it did in this way, it can suppress that the electric current amount consumed with the hydraulic power steering apparatus 1 in a high load state becomes excessive. Since the first electric pump 22 and the second electric pump 23 are alternately operated in a high load state, one of the first and second electric pumps 22 and 23 deteriorates faster than the other. Thus, the life of the hydraulic power steering device 1 can be extended. In addition, the hydraulic oil can be prevented from staying in any one of the branched portions of the supply oil passage 55.

  (2) When the target rotation speed N * is less than the low rotation threshold N_lo, either one of the first and second electric pumps 22 and 23 is operated and the other is stopped. It is possible to suppress power saving. Since the first electric pump 22 and the second electric pump 23 are alternately operated in the low assist state, one of the first and second electric pumps 22 and 23 deteriorates faster than the other. This can be further suppressed, and the life of the hydraulic power steering apparatus 1 can be further extended.

  (3) Based on the first and second instruction flags Fi1 and Fi2 stored in the non-volatile memories 71a and 73a, the electric pump (one electric pump) operated in the high load state or the low assist state and the electric motor to be stopped The pump (other electric pump) was determined. Since the states of the first and second instruction flags Fi1, Fi2 stored in the memories 71a, 73a are maintained even after the IG is turned off, the first electric pump 22 is appropriately applied before and after the IG is turned off. And the second electric pump 23 can be operated alternately.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, the electric pump to be operated and the electric pump to be stopped are determined based on the first and second instruction flags Fi1 and Fi2 stored in the non-volatile memories 71a and 73a. For example, the electric pump to be operated and the electric pump to be stopped may be determined based on the first and second instruction flags stored in the volatile memory. Even with this configuration, the first electric pump 22 and the second electric pump can be operated alternately between the time when the IG is turned on and the time when the IG is turned off.

  In the above embodiment, when the target rotation speed N * is less than the low rotation threshold N_lo, either one of the first and second electric pumps 22 and 23 is not stopped, and both are operated, thereby causing the hydraulic cylinder 21 to Hydraulic oil may be supplied.

  In the above embodiment, every time the state where either one of the first and second electric pumps 22 and 23 is operated (high load state or low assist state) and the state where both are operated is switched once. The on / off states of the second instruction flags Fi1 and Fi2 are inverted. However, the present invention is not limited to this. For example, each time the first and second electric pumps 22 and 23 are activated and the state in which both are activated are switched a predetermined number of times in advance, the first and second instruction flags are switched. The on / off states of Fi1 and Fi2 may be reversed. Further, for example, the ON / OFF state of the first and second instruction flags Fi1 and Fi2 may be reversed every time the operating time in the high load state or the low assist state elapses for a predetermined time, the high load state or the low assist state. The mode of switching between the electric pump to be operated and the electric pump to be stopped can be appropriately changed.

In the above embodiment, the first and second electric pumps 22 and 23 are provided as the hydraulic pressure source of the hydraulic cylinder 21, but three or more electric pumps may be provided.
In the above embodiment, the first and second electric pumps 22 and 23 have the first and second ECUs 43 and 46, respectively. However, the present invention is not limited to this, and the first and second motors 41 and 41 are configured by one ECU. The operation of 44 may be controlled.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic power steering apparatus, 2 ... Steering wheel, 21 ... Hydraulic cylinder, 22 ... 1st electric pump, 23 ... 2nd electric pump, 41 ... 1st motor, 42 ... 1st pump, 43 ... 1ECU, 44 ... 2nd motor, 45 ... 2nd pump, 46 ... 2ECU, 61 ... CAN, 71 ... 1st microcomputer, 71a, 73a ... Memory, 73 ... 2nd microcomputer, 75 ... In-vehicle power supply, Fd1 ... 1st operation determination flag, Fd2 ... second operation determination flag, Fi1 ... first instruction flag, Fi2 ... second instruction flag, Fp1 ... first inversion permission flag, Fp2 ... second inversion permission flag, I_th ... upper limit current value, N * ... target rotation speed , N_lo: Low rotation threshold.

Claims (3)

In a control device for a hydraulic power steering apparatus including a plurality of electric pumps for supplying hydraulic oil to a hydraulic actuator that generates assist force,
When the value of the current flowing through at least one of the motors serving as the drive source of each electric pump is equal to or greater than a predetermined upper limit current value indicating that the load on the motor is high, one of the electric pumps Actuate the electric pump and stop other electric pumps.
A control device for a hydraulic power steering device, wherein the one electric pump and the other electric pump are sequentially switched. In the control device of the hydraulic power steering device according to claim 1,
When the target rotational speed of the motor is less than a predetermined low rotation threshold value indicating that the required flow rate of hydraulic fluid is small, one of the electric pumps is operated and another electric motor is operated. To stop the pump,
A control device for a hydraulic power steering device, wherein the one electric pump and the other electric pump are sequentially switched. In the control device of the hydraulic power steering device according to claim 1 or 2,
An instruction flag provided for each of the electric pumps and indicating whether the electric pump should operate as the one electric pump;
A nonvolatile memory for storing the state of the instruction flag,
The control apparatus for a hydraulic power steering apparatus, wherein the one electric pump and the other electric pump are determined based on the state of each instruction flag.