JP4483321B2 - Hydraulic power steering device - Google Patents

Description

  The present invention relates to a power steering device used for an automobile or the like, and more particularly to a hydraulic power steering device having a function of electronically controlling the flow rate of a working fluid supplied to a power cylinder.

  Conventionally, as a hydraulic power steering device, for example, for the purpose of improving the controllability of the steering assist force according to the vehicle speed value, the steering angle, the steering wheel angular velocity, etc., and reducing the power consumption of the hydraulic pump in the standby state, etc. There is a valve provided with a VFC (Variable Flow Control) control valve for electronically controlling the discharge flow rate of the hydraulic pump (see, for example, Patent Documents 1 and 2). In addition to this, in order to realize better steering characteristics, PPS (Progressive Power) that electronically controls the magnitude of the steering assist force according to the running state, the steering state, etc. without depending on the discharge flow rate of the hydraulic pump. Some have a Steering control valve. For example, a device configured to adjust a flow rate ratio of the working fluid supplied to the power cylinder among the discharge flow rate by a PPS control valve (see, for example, Patent Document 3), or a hydraulic reaction force applied to the steering shaft ( A device configured to adjust the magnitude of the acting force against the steering assist force) by a PPS control valve (see, for example, Patent Document 4) and a communication state between a pair of pressure chambers of a power cylinder, There exists an apparatus (for example, patent document 5) etc. which were comprised so that it might adjust with a PPS control valve.

Japanese Patent Laid-Open No. 11-59451 JP 2001-163233 A Japanese Patent No. 3407482 Japanese Patent Publication No. 8-11538 JP 61-67664 A

  However, the conventional hydraulic power steering apparatus has the following problems. That is, when the control valves are in an unintended control state, the entire power steering device may fall into an unintended control state.

  The present invention provides a hydraulic power steering apparatus including a control valve for adjusting the flow rate of a working fluid, which has a fail-safe function and has high operation reliability.

A first invention includes a hydraulic pump that discharges a working fluid, a power cylinder having a piston and a pair of pressure chambers that drive the piston, a first control valve that controls a discharge flow rate of the hydraulic pump, and two types A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of these throttles, and the flow rate ratio of the working fluid that passes through one of the two throttles is controlled. A hydraulic power steering apparatus including: a second control valve that controls; a control controller that controls the first control valve and the second control valve;
The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Oh it is,
The first control valve is configured to suppress the discharge flow rate when energization is stopped, and the second preliminary control map passes through the one throttle as compared with the main control map. A control map for controlling the second control valve so as to increase the flow rate of the working fluid that generates the steering assist force in the power cylinder of the working fluid by reducing the flow rate of the working fluid;
When the energization stops, the second control valve increases a flow rate ratio of the working fluid that passes through the one throttle and generates a steering assist force in the power cylinder of the working fluid. The first preliminary control map is a control map for controlling the first control valve so as to increase the discharge flow rate as compared with the main control map. The hydraulic power steering apparatus is characterized in that (claim 1).
The second invention includes a hydraulic pump that discharges a working fluid, a power cylinder having a piston and a pair of pressure chambers that drive the piston, a first control valve that controls a discharge flow rate of the hydraulic pump, and two types A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of these throttles, and the flow rate ratio of the working fluid that passes through one of the two throttles is controlled. A hydraulic power steering apparatus including: a second control valve that controls; a control controller that controls the first control valve and the second control valve;
The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
The first control valve is configured to suppress the discharge flow rate when energization is stopped, and the second preliminary control map passes through the one throttle as compared with the main control map. A control map for controlling the second control valve so as to increase the flow rate of the working fluid that generates the steering assist force in the power cylinder of the working fluid by reducing the flow rate of the working fluid;
When the energization stops, the second control valve reduces a flow rate ratio of the working fluid that passes through the one throttle, and among the working fluids, a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder. The first preliminary control map is a control map for controlling the first control valve so as to suppress the discharge flow rate as compared with the main control map. The hydraulic power steering apparatus is characterized in that (Claim 2).
A third invention includes a hydraulic pump that discharges a working fluid, a power cylinder having a piston and a pair of pressure chambers that drive the piston, a first control valve that controls a discharge flow rate of the hydraulic pump, and two types A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of these throttles, and the flow rate ratio of the working fluid that passes through one of the two throttles is controlled. A hydraulic power steering apparatus including: a second control valve that controls; a control controller that controls the first control valve and the second control valve;
The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
The first control valve is configured to increase the discharge flow rate when energization is stopped, and the second preliminary control map is configured to pass the one throttle as compared with the main control map. A control map for controlling the second control valve so as to suppress a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder of the working fluid by increasing a flow rate ratio of the working fluid;
When the energization stops, the second control valve increases a flow rate ratio of the working fluid that passes through the one throttle and generates a steering assist force in the power cylinder of the working fluid. The first preliminary control map is a control map for controlling the first control valve so as to increase the discharge flow rate as compared with the main control map. The hydraulic power steering apparatus is characterized in claim 3.
A fourth invention includes a hydraulic pump that discharges a working fluid, a power cylinder having a piston and a pair of pressure chambers that drive the piston, a first control valve that controls a discharge flow rate of the hydraulic pump, and two types A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of these throttles, and the flow rate ratio of the working fluid that passes through one of the two throttles is controlled. A hydraulic power steering apparatus including: a second control valve that controls; a control controller that controls the first control valve and the second control valve;
The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
The first control valve is configured to increase the discharge flow rate when energization is stopped, and the second preliminary control map is configured to pass the one throttle as compared with the main control map. A control map for controlling the second control valve so as to suppress a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder of the working fluid by increasing a flow rate ratio of the working fluid;
When the energization stops, the second control valve reduces a flow rate ratio of the working fluid that passes through the one throttle, and among the working fluids, a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder. The first preliminary control map is a control map for controlling the first control valve so as to suppress the discharge flow rate as compared with the main control map. The hydraulic power steering apparatus is characterized in that (4).

The hydraulic power steering apparatus of the present invention has a detection function for detecting whether the operating state of each control valve is good or bad. When the control function detects a defective operation state of the control valve by the detection function, the control controller stops energization of the control valve and switches the control map applied to the normal control valve. It is configured.
That is, for example, when a defective operation state of the second control valve is detected, a control map to be applied to the first control valve is turned off from the main control map when the second control valve is turned off. It is switched to the first preliminary control map. Then, only the first control valve is controlled based on the first preliminary control map. In addition, for example, when a defective operation state of the first control valve is detected, a control map to be applied to the second control valve is turned off from the main control map when the first control valve is turned off. Switching to the second preliminary control map is performed. Then, only the second control valve is controlled based on the second preliminary control map.

  If energization to one of the above control valves is stopped, the valve opening degree can be fixed. If the other control valve is controlled based on each preliminary control map with the valve opening of one control valve fixed, the hydraulic power steering device can be controlled. Therefore, the hydraulic power steering apparatus has high controllable operation reliability even when any of the control valves is in a defective operation state.

As described above, the hydraulic power steering apparatus of the present invention has a high operation reliability having a fail-safe function that can cope with an unintended control state of each control valve.
As the control map, for example, a calculation formula for calculating a control value of each control valve using each value such as a vehicle speed value and a steering wheel steering angle as a variable may be used.

  In the present invention, the hydraulic power steering apparatus includes a vehicle speed sensor that measures a vehicle speed value, and a steering wheel angle sensor that measures a steering wheel angle input to the steering handle. The vehicle speed value and the steering angle of the steering wheel are inputted, and the steering wheel angular velocity is calculated based on the steering wheel steering angle. Each control map includes a first control valve or a second control valve. For at least one of the control valves, control values corresponding to the vehicle speed value, the steering angle, and the steering wheel angular speed are preferably arranged.

In this case, in the hydraulic power steering device that realizes a good steering feeling by appropriately controlling the steering assist force with respect to the vehicle speed value, the steering wheel angle, and the steering wheel angular velocity, the operation reliability is ensured by the fail-safe function for each control valve. Can be improved.
As a method of calculating the steering wheel angular velocity, for example, there is a method of storing a steering wheel angle inputted in time series and calculating a time difference or a temporal differentiation for the steering wheel angle inputted at different times.

In addition, the control controller is configured to duty-control the first control valve and the second control valve made up of electromagnetic valves, and the detection function energizes the first control valve and the second control valve. it is preferable to measure a current value, is arranged to detect a faulty operating condition of the control valves based on the current value measured for (claim 5).
In this case, by measuring the current value that flows through each control valve during duty control, the operation of each control valve can be performed with high certainty without setting the detection mode separately from the normal control of each control valve. The state can be detected.

In the first and second aspects of the invention, the first control valve is configured to suppress the discharge flow rate when energization is stopped, and the second preliminary control map is the main control map. The second control valve is controlled so as to increase the flow rate ratio of the working fluid that generates the steering assist force in the power cylinder by reducing the flow rate ratio of the working fluid that passes through the one throttle. It is a control map .
In this case, when the discharge flow rate is reduced by stopping energization of the first control valve, the working fluid that generates the steering assist force in the power cylinder out of the discharge flow rate of the hydraulic pump by the control of the second control valve. The flow rate of can be increased. Therefore, even if the first control valve becomes defective, the steering assist force of the hydraulic power steering device can be ensured to some extent.

In the third and fourth aspects of the invention, the first control valve is configured to increase the discharge flow rate when energization is stopped, and the second preliminary control map is the same as the main control map. In comparison, the second control is performed so that the flow rate ratio of the working fluid passing through the one throttle is increased to suppress the flow rate ratio of the working fluid that generates the steering assist force in the power cylinder. It is a control map which controls a valve .
In this case, when the discharge flow rate is increased by stopping energization of the first control valve, the working fluid that generates the steering assist force in the power cylinder out of the discharge flow rate of the hydraulic pump by the control of the second control valve. The flow rate ratio can be suppressed. Therefore, even if the first control valve becomes defective, it is possible to avoid the possibility that the steering assist force of the hydraulic power steering device becomes excessive. Therefore, in particular, it is possible to suppress the generation of an excessive steering assist force during high-speed traveling and maintain the traveling stability of the vehicle.

In the first and third aspects of the invention, the second control valve increases the flow rate ratio of the working fluid that passes through the one throttle when the energization is stopped, and is steered by the power cylinder of the working fluid. The flow rate ratio of the working fluid that generates the assist force is configured to be suppressed, and the first preliminary control map controls the first control valve to increase the discharge flow rate as compared with the main control map. It is a control map .
In this case, when the flow rate ratio of the working fluid that generates the steering assist force in the power cylinder is reduced in the discharge flow rate, the working fluid supplied from the hydraulic pump to the power cylinder is controlled by the control of the first control valve. The flow rate itself can be increased. Therefore, even if the second control valve becomes defective, the steering assist force of the hydraulic power steering device can be ensured to some extent.

In the second and fourth inventions, when the energization is stopped , the second control valve reduces the flow rate of the working fluid that passes through the one throttle and is steered by the power cylinder of the working fluid. The flow rate ratio of the working fluid that generates the assist force is increased, and the first preliminary control map controls the first control valve so as to suppress the discharge flow rate as compared with the main control map. This is a control map .
In this case, when the flow rate ratio of the working fluid that generates the steering assist force in the power cylinder in the discharge flow rate increases, the operation that is supplied from the hydraulic pump to the power cylinder by the control of the first control valve. The flow rate of the fluid itself can be suppressed. Therefore, even if the second control valve becomes defective, there is little possibility that the steering assist force of the hydraulic power steering device becomes excessive. Therefore, particularly, the steering assist force during high-speed traveling can be appropriately suppressed to maintain traveling stability.

Example 1
This example relates to a hydraulic power steering device for an automobile in which the control valve for adjusting the flow rate is electronically controlled to improve the controllability of the steering assist force. This content will be described with reference to FIGS.
As shown in FIGS. 1 to 3, the hydraulic power steering apparatus 1 of this example is driven by an engine (not shown) to discharge a working fluid, a piston 200, and a pair of pressures that drive the piston 200. A power cylinder 20 having chambers 231 and 232, a first control valve 41 (in this example, a VFC control valve 41) for controlling the discharge flow rate of the hydraulic pump 10, and a working fluid supplied to the power cylinder 20 out of the discharge flow rate. This is a device including a second control valve 21 (in this example, a PPS control valve 21) for controlling the flow rate ratio, and a control controller 50 for controlling the VFC control valve 41 and the PPS control valve 21.

As shown in the figure, the controller 50 includes a memory function storing a control map in which control values for controlling the VFC control valve 41 and the PPS control valve 21 are arranged, and the VFC control valve 41 and the PPS control valve 21. And a detection function for detecting whether the operating state is good or bad.
Then, the control controller 50 of this example controls the VFC control valve 41 and the PPS control valve 21 with the main control map when it is detected that the operating state of the VFC control valve 41 and the PPS control valve 21 is good. Further, the control controller 50 stops the energization of the PPS control valve 21 when the detection function detects a defective operation state of the PPS control valve 21 and applies a control map applied to the VFC control valve 41 to the first. Switching to the preliminary control map, and when the detection function detects a defective operation state of the VFC control valve 41, the control map to be applied to the PPS control valve 21 and to stop the energization to the VFC control valve 41 is the second preliminary control map. It is comprised so that it may switch to.
This content will be described in detail below.

  As shown in FIGS. 1 and 2, the power steering device 1 of this example includes a rack and pinion type gear mechanism in which a rack shaft (not shown) having a rack gear and a pinion shaft 33 having a pinion gear engage with each other. An accommodated steering gear box 35 is provided. This power steering device 1 is a hydraulic circuit that discharges a working fluid as a hydraulic pressure source as a hydraulic circuit, a power cylinder 20 that applies a steering assist force to a rack shaft, and an operation between the hydraulic pump 10 and the power cylinder 20. And a servo valve 30 for switching a fluid flow path. Here, the power steering apparatus 1 of the present example includes a VFC control valve 41 that controls the discharge flow rate of the hydraulic pump 10 and a PPS that controls the flow rate ratio of the working fluid supplied to the power cylinder 20 out of the discharge flow rate of the hydraulic pump 10. And a control valve 21.

The hydraulic pump 10 of this example shown in FIGS. 1 and 2 is a vane type pump. The drive shaft is connected to an output shaft of a vehicle engine (not shown) via a pulley belt 110 disposed on a belt pulley 11 that rotates integrally with the drive shaft. The power cylinder 20 is configured such that the piston 200 (FIG. 3) slides due to a differential pressure between a pair of pressure chambers 231 and 232 (FIG. 3) disposed on both ends. The servo valve 30 is disposed on the outer periphery of the pinion shaft 33 that transmits the rotation of the steering shaft 32 connected to the steering handle 31.
That is, the power steering device 1 of this example controls the rotation of the servo valve 30 by the operation torque input to the steering handle 31 and appropriately switches the flow path of the working fluid discharged from the hydraulic pump 10 to each pressure chamber 231, It is a hydraulic type that performs supply / discharge control to H.232. The power steering apparatus 1 of this example is configured to steer steering wheels (not shown) by applying the steering assist force generated in the power cylinder 20 to the rack shaft.

  As shown in FIGS. 1 and 2, the power steering apparatus 1 detects a steering angle inputted to the steering handle 31 and a controller 50 for controlling the VFC control valve 41 and the PPS control valve 21. Steering angle sensor 310 and a vehicle speed sensor 510 for detecting the speed of the vehicle. The control controller 50 is connected to a CAN (Controller Area Network) network 500 in the vehicle together with the steering angle sensor 310 and the vehicle speed sensor 510. The steering angle sensor 310 is a sensor configured to detect the steering angle based on a signal output from a rotary encoder (not shown) connected to the steering shaft 32. The vehicle speed sensor 510 is a sensor configured to detect a vehicle speed from the frequency of a pulse signal generated by the tachometer using a tachometer disposed on an output shaft of a transmission (not shown).

  As shown in FIG. 3, the power steering device 1 of this example is configured by a hydraulic circuit similar to that described in Patent Document 3 above. In the same figure, the servo valve 30 of this example in which eight low-speed diaphragms (indicated by L in the figure) and two high-speed diaphragms (indicated by H in the figure) are formed. It is expressed as ten stops. In this hydraulic circuit, the working fluid discharged from the hydraulic pump 10 is mainly distributed to the pressure chambers 231 and 232 of the power cylinder 20 to generate a steering assist force. A part of the working fluid passes through the high-speed throttle and the PPS control valve 21 in the hydraulic circuit branched from the pressure chambers 231 and 232 and is not supplied to the reservoir tank 413 without being used for generating the steering assist force. Inflow.

  Here, as shown in FIG. 4, the hydraulic pump 10 of this example is a mechanism for controlling the discharge flow rate as described above, and includes a VFC control valve 41 including an electromagnetic valve described in Patent Document 1. It has a flow rate control mechanism 40 configured as a center. The flow rate control mechanism 40 receives the working fluid discharged from the hydraulic pump 10 from the inlet 402, discharges a part of the working fluid to the reflux path 404 by the action of the spool valve member 406, and removes the remaining working fluid. It is configured to supply the servo valve 30 from the outflow port 403. In the reflux path 404, a communication path that opens into the working fluid stored in the reservoir tank 413 is provided.

The flow rate control mechanism 40 includes a throttle member 412 having an axial through-hole 421, a spool valve member 406 biased toward the throttle member 412, and a plunger 450 integrally formed with a valve body 451. And a valve 41.
The throttle member 412 has a port 422 in which a through hole 421 opens at an end portion on the spool valve member 406 side, and a variable throttle 405 that cooperates with the valve body 451 is formed at an end portion on the valve body 451 side. In addition, a through hole 425 that guides the working fluid flowing in from the inflow port 402 into the through hole 421 is formed in the body portion near the port 422 in the throttle member 412. Further, the spool valve member 406 is configured to be biased by a spring 441 and is in contact with the end portion of the throttle member 412 in a normal original position. The spool valve member 406 blocks communication between the port 422 and the reflux path 404 at the original position in contact with the throttle member 412, and communicates the port 422 and the reflux path 404 when displaced against the spring 441. It is configured as follows.

The pressure after passing through the variable throttle 405 acts on the end of the spool valve member 406 on the spring 441 side via the pressure passage 442. Further, the pressure before passing through the variable throttle 405 acts on the opposite end of the spool valve member 406. That is, the spool valve member 406 is configured to operate according to the pressure difference between the variable throttle 405 and the back thereof.
Here, when the flow rate from the hydraulic pump 10 increases and the pressure difference before and after the variable throttle 405 exceeds a predetermined value, the spool valve member 406 is displaced away from the throttle member 412 due to the differential pressure on both ends. As a result, the inlet 402 and the reflux path 404 communicate with each other, and the flow rate of the working fluid flowing in from the inlet 402 toward the hydraulic pump 10 increases. The flow rate control mechanism 40 of the present example maintains the flow rate discharged from the outlet 403 at a substantially constant value regardless of the increase in the flow rate from the hydraulic pump 10 by increasing the flow rate of reflux. In the flow rate control mechanism 40, the substantially constant flow rate discharged from the outlet 403 changes depending on the opening of the variable throttle 405.

  The opening degree of the variable throttle 405 is controlled by the VFC control valve 41 made of an electromagnetic valve. The VFC control valve 41 includes a plunger 450, a solenoid 419 that attracts the plunger 450, and a spring 453 that applies a biasing force toward the valve body 451 to the plunger 450. When the solenoid 419 is energized, the plunger 450 and the valve body 451 are sucked, whereby the valve body 451 is separated from the throttle member 412 and the opening of the variable throttle 405 is increased. On the other hand, when the energization to the solenoid 419 is stopped, the valve body 451 comes into contact with the throttle member 412, and the variable throttle 405 becomes the minimum opening.

Therefore, in the flow rate control mechanism 40, when the energization of the VFC control valve 41 is stopped, the variable throttle 405 becomes the minimum opening, and a pressure difference between the variable throttle 405 is likely to occur, and the flow rate discharged from the outlet 403 Decrease. On the other hand, when the VFC control valve 41 is energized, the opening of the variable throttle 405 is increased and the occurrence of a pressure difference before and after the variable throttle 405 is suppressed, so that the flow rate discharged from the outlet 403 increases.
In this example, the valve opening is controlled by duty control in which a periodic pulse voltage is applied to the solenoid 419 so that the valve opening of the VFC control valve 41 can be controlled continuously. Furthermore, instead of the VFC control valve 41 formed of the electromagnetic valve of this example, it is also possible to apply a control valve configured such that the valve opening degree can be changed by a stepping motor, for example.

  Further, as described above, in the hydraulic circuit of the power steering apparatus 1 of this example, as shown in FIG. 3, the PPS control is performed in the hydraulic path for supplying the working fluid from the hydraulic pump 10 to the pressure chambers 231, 232 of the power cylinder 20. A hydraulic path communicating with the reservoir tank 413 via the valve 21 is connected. That is, the PPS control valve 21 is configured to control the opening degrees of the communication passage 235 communicating with the pressure chambers 231 and 232 and the communication passage 236 communicating with the reservoir tank 413. That is, the PPS control valve 21 in this example is supplied to the power cylinder 20 by letting a part of the working fluid supplied from the hydraulic pump 10 toward the pressure chamber 231 (232) to the reservoir tank 413, and is used for steering assist. It is a valve for controlling the flow rate of the working fluid that generates force and adjusting the pressure in the pressure chamber 231 (232).

  The PPS control valve 21 is described in JP-A-11-94120. As shown in FIG. 5, the valve body 214, a spool 226 slidably inserted into an inner hole 215 of the valve body 214, and the spool And a solenoid 219 for applying a driving force to the H.226. In the PPS control valve 21, a first port 213 communicating with the communication passage 235 is formed at the tip of the inner hole 215 of the valve body 214, and an annular groove 212 is formed on the inner periphery of the inner hole 215. For 212, the second port 211 through which the communication path 236 communicates opens at four circumferentially spaced intervals.

  The spool 226 has an annular groove 227 formed in its body. In addition, a pass hole 223 that penetrates in the axial direction and a lateral hole 222 that communicates the groove 227 and the pass hole 223 are bored inside the spool 226. Further, a U-shaped slit groove 224 that opens to the groove portion 227 along the axial direction is provided on the outer peripheral surface of the body portion of the spool 226, and the slit groove 224 is variable in cooperation with the annular groove 212. Configured to form an aperture. That is, the first port 213 connected to the communication path 235 and the second port 211 connected to the communication path 236 communicate with each other through this variable throttle.

The spool 226 slidably inserted into the inner peripheral surface of the inner hole 215 is urged toward the first port 213 by the urging force of the spring 218 in a normal original position. When the spool 226 is in the original position, most of the slit groove 224 overlaps with the annular groove 212, and the opening of the variable throttle formed by the slit groove 224 and the annular groove 212 is maximized. In this case, most of the working fluid discharged from the hydraulic pump 10 via the VFC control valve 41 is bypassed to the reservoir tank 413 via the PPS control valve 21 and the flow rate ratio supplied to the power cylinder 20 is reduced. descend. On the other hand, when the solenoid 219 is energized, as the spool 226 is displaced against the spring 218, the overlapping range in the axial direction between the slit groove 224 and the annular groove 212 is reduced, and the opening of the variable throttle is reduced. . In this case, the flow rate bypassed from the hydraulic pump 10 to the reservoir tank 413 via the PPS control valve 21 decreases, while the flow rate supplied to the pressure chamber 231 (232) of the power cylinder 20 increases.
In this example, the valve opening is controlled by duty control in which a periodic pulse voltage is applied to the solenoid 219 so that the valve opening of the PPS control valve 21 can be continuously controlled. Furthermore, instead of the PPS control valve 21 formed of the electromagnetic valve of this example, it is also possible to apply a control valve configured such that the valve opening degree can be changed by a stepping motor, for example.

  As shown in FIG. 6, the controller 50 includes a CPU that executes various calculations necessary to control the VFC control valve 41 and the PPS control valve 21, a RAM as a work area at the time of calculation, A microcomputer 51 incorporating a ROM as a memory function storing a control map and a control program for controlling the control valves 41 and 21, a CAN interface, and a drive circuit for driving the control valves 41 and 21 in a duty cycle 52 and a current detection circuit 53 for detecting a current value supplied to each control valve 41, 21.

  As shown in the figure, the microcomputer 51 calculates a target control duty ratio of each control valve 41, 21 and applies a voltage having a magnitude corresponding to the target control duty ratio to the drive circuit 52. . The drive rotation 52 is configured to output a periodic pulse voltage having a predetermined duty ratio in accordance with the applied voltage, and to drive the control valves 41 and 21 in a duty manner. Note that the controller 50 of this example is configured to receive output signals of the steering angle sensor 310 and the vehicle speed sensor 510 from the CAN network 500.

As shown in FIG. 7, the ROM in the microcomputer 51 stores a determination map for determining whether the VFC control valve 41 or the PPS control valve 21 is operating normally. In this example, as shown in the figure, for the VFC control valve 41 or the PPS control valve 21, an appropriate current value range a with respect to the command current value is experimentally obtained in advance, and the current value range a is based on the current value range a. A decision map was created. Here, the horizontal axis of the figure shows the command current value of the VFC control valve 41 or the PPS control valve 21, and the vertical axis shows the current value of the control valve 41 energized. A solid line c passing through the points of the current value Im and the command current value Im ′ indicates a change in an ideal current value that is supplied to the VFC control valve 41 or the PPS control valve 21.
In FIG. 7, the meaning of large command current is different between the VFC control valve 41 and the PPS control valve 21. When the command current of the VFC control valve 41 is large, the valve opening becomes the maximum opening, and when the command current of the PPS control valve 21 is large, the valve opening becomes the minimum opening.

  The detection function for determining the quality of the operation state of each control valve 41, 21 is configured by combining a determination map and the current detection circuit 53. In this detection function, it is determined whether or not the current value detected by the current detection circuit 53 is appropriate for the target control duty ratio set for each control valve 41 and 21. Then, when the detected current value is outside the range defined by the determination map (region b indicated by hatching), it is determined that the VFC control valve 41 or the PPS control valve 21 is in a defective operating state.

  Furthermore, three types of four control maps are stored in the ROM as control maps for controlling at least one of the VFC control valve 41 and the PPS control valve 21. The first control map is a control map for the VFC control valve 41 and a main control map for controlling the PPS control valve 21 when both the VFC control valve 41 and the PPS control valve 21 are operating normally. Two main control maps are prepared, one applied to the VFC control valve 41 and the other applied to the PPS control valve 21. The second control map is a second preliminary control map for controlling the PPS control valve 21 when the VFC control valve 41 is in a defective operation state. The third control map is a first preliminary control map for controlling the VFC control valve 41 when the PPS control valve 21 is in a defective operation state.

  The PPS control valve 21 of this example is basically controlled using only the vehicle speed value as a control variable, and at the time of stationary (steering of the steering wheel at a vehicle speed of zero), the current value supplied to the control valve is maximized, and the steering assist force The control map is configured so as to reduce the steering load by reducing the steering load, reduce the current value during high-speed running, and reduce the steering assist force to obtain running stability. On the other hand, as described in Patent Document 2, the VFC control valve 41 uses a value other than the vehicle speed value as a control variable. If the steering angle is used as a control variable, steering and non-steering are recognized based on the steering angle, and when non-steering (when steering assist is unnecessary), the discharge flow rate is reduced (energization current value is reduced) to save energy. Can be achieved. If the steering wheel angular velocity obtained by differentiating the steering angle of the steering wheel is used as a control variable, sudden steering and slow steering are recognized based on the steering wheel angular velocity, and the discharge flow rate is increased (the energization current value is increased) during sudden steering. Thus, it is possible to suppress the response delay of the steering assist. Then, a control map having the vehicle speed value, steering wheel steering angle and steering wheel angular velocity as control variables is prepared, and these control maps are combined, or the control values obtained from the respective control maps are added to obtain the final control. Get value.

  In addition, the control variable of each control valve 41 and 21 can be changed suitably. For example, the PPS control valve 21 can be controlled using not only the vehicle speed value but also the steering wheel steering angle and steering wheel angular velocity as control variables. Further, as the control map, a calculation formula for calculating an appropriate control value using a vehicle speed value, a steering wheel steering angle or the like as a variable can be used.

  Next, the contents of each control map will be described using only the vehicle speed value as a control variable. Here, for easy explanation, the values of the steering wheel steering angle and the steering wheel angular velocity among the control variables applied to the VFC control valve 41 are fixed. In FIG. 8, the target control duty ratio of the VFC control valve 41 according to the main control map is indicated by a solid line a, and the target control duty ratio of the VFC control valve 41 according to the first preliminary control map is indicated by a broken line b. In FIG. 9, the target control duty ratio of the PPS control valve 21 based on the main control map is indicated by a solid line a, and the target control duty ratio of the PPS control valve 21 based on the second preliminary control map is indicated by a broken line b. In both figures, the horizontal axis represents the vehicle speed value as a control variable, and the vertical axis represents the target control duty ratio for duty-controlling the control valves 41 and 21. Here, the duty ratio is a ratio indicating a ratio of energization time in one cycle with respect to the periodic pulse-like drive voltage applied to each control valve 41, 21. If continuous energization, the duty ratio is 100%, and if energization is stopped. If the duty ratio is 0%, the energization time is 70% and the non-energization time is 30%, the duty ratio is 70%.

  In the power steering device 1 of this example, as indicated by the solid line a in FIG. 8, the target control duty ratio of the VFC control valve 41 is reduced and the valve opening degree is suppressed as the vehicle speed increases. The discharge flow rate of the hydraulic pump 10 is decreased. Further, as shown by the solid line a in FIG. 9, the target control duty ratio of the PPS control valve 21 is reduced as the vehicle speed increases, and the valve opening degree is increased to be supplied to the pressure chamber 231 (232). Reduce the flow rate of the working fluid. In other words, the power steering device 1 of this example is configured to reduce the steering assist force as the vehicle speed increases, thereby realizing vehicle speed sensitive control.

  First, the contents of the first preliminary control map will be described as shown in FIG. This first preliminary control map is a map for controlling the VFC control valve 41 after the energization of the PPS control valve 21 in which trouble has occurred is stopped. When energization of the PPS control valve 21 is stopped (duty ratio 0%), the valve opening becomes the maximum opening. When the valve opening degree of the PPS control valve 21 reaches the maximum opening degree, the flow rate ratio of the working fluid supplied to the pressure chamber 231 (232) of the power cylinder 20 in the discharge flow rate of the hydraulic pump 10 decreases, and the steering assist is performed. There is a risk of lack of power. Therefore, in the first preliminary control map, as indicated by the broken line b in FIG. 8, the target control duty ratio of the VFC control valve 41 is set to be larger than normal (solid line a in the figure). Then, the valve opening degree of the VFC control valve 41 can be increased to increase the discharge flow rate of the hydraulic pump 10, and the absolute flow rate of the working fluid supplied from the hydraulic pump 10 to the pressure chamber 231 (232) can be increased to increase the power cylinder 20. The steering assist force obtained with can be increased.

  Next, as shown in FIG. 9, the contents of the second preliminary control map will be described. This second preliminary control map is a control map applied to the PPS control valve 21 after the energization of the troubled VFC control valve 41 is stopped. When energization of the VFC control valve 41 is stopped (duty ratio 0%), the valve opening becomes the minimum opening. And when the valve opening degree of the VFC control valve 41 becomes the minimum opening degree, the discharge flow rate of the hydraulic pump 10 decreases, and the steering assist force may be insufficient. Therefore, in the second preliminary control map, as indicated by the broken line b in FIG. 9, the target control duty ratio of the PPS control valve 21 is set to be larger than normal (solid line a in the figure). Then, by suppressing the valve opening degree of the PPS control valve 21, the ratio of the flow rate supplied to the pressure chamber 231 (232) of the power cylinder 20 in the discharge flow rate of the hydraulic pump 10 can be increased to increase the absolute flow rate. The steering assist force obtained by the power cylinder 20 can be increased.

A method for controlling the power steering apparatus 1 of this example will be described with reference to FIG.
First, in step S11, it is determined whether or not the engine speed is equal to or higher than a specified speed. If this determination condition is met, step S12 and subsequent steps are executed, and if not, the control is terminated. In this example, in order to determine whether or not the engine has been started, the specified rotation speed is set to 100 rotations. In step S12, a vehicle speed value is input from the vehicle speed sensor 510, and a steering wheel steering angle is input from the steering angle sensor 310. In step S13, the steering wheel angular velocity is calculated based on the steering wheel steering angle sampled in the past. Further, in step S14, a current value I1 energized to the VFC control valve 41 and a current value I2 energized to the PPS control valve 21 are detected.

  In step S15, the suitability of the current value I1 is determined based on the target control duty ratio T1 of the VFC control valve 41 set in the previous control loop, and the target control duty ratio of the PPS control valve 21 set in the previous control loop. Whether or not the current value I2 is appropriate is determined based on T2. Specifically, as shown in FIG. 7, the control valve 41 (21) depends on whether or not the current value to be energized when the control valve 41 (21) is duty-driven at the target control duty ratio T 2 is in an appropriate range. The poor operating state was determined.

  If it is determined that the current values I1 and I2 are both in an appropriate range and both the VFC control valve 41 and the PPS control valve 21 are normal, step S161 is executed. In step S161, a main control map stored in advance in the ROM of the microcomputer 51 is referred to based on the input vehicle speed value, the steering wheel steering angle, and the calculated steering wheel angular velocity. Then, the target control duty ratio T1 is obtained as the control value of the VFC control valve 41, and the target control duty ratio T2 is obtained as the control value of the PPS control valve 21. Thereafter, the process proceeds to step S162, where the VFC control valve 41 is controlled with the new target control duty ratio T1, and the PPS control valve 21 is controlled with the new target control duty ratio T2.

  On the other hand, when the current value I1 is in the proper range and the VFC control valve 41 is determined to be normal, and the current value I2 is outside the proper range and the PPS control valve 21 is determined to be abnormal, The process proceeds to step S171. In step S171, the first preliminary control map is referred to based on the vehicle speed value, the steering wheel steering angle, and the steering wheel angular speed, and the target control duty ratio T1sub is obtained as the control value of the VFC control valve 41. Thereafter, the process proceeds to step S172, where the VFC control valve 41 is controlled by the new target control duty ratio T1sub, and energization is stopped to turn off the PPS control valve 21 (duty ratio zero). As described above, since the valve is opened when energization to the PPS control valve 21 is stopped, the flow rate ratio of the working fluid supplied to the pressure chamber 231 (232) decreases. On the other hand, in step S171 and step S172, based on the first preliminary control map as shown in FIG. 8, the target control duty ratio of the VFC control valve 41 is increased compared to the normal operation of the PPS control valve 21, The discharge flow rate of the hydraulic pump 10 is increased by controlling the opening degree of the valve to be increased or decreased. Then, the absolute flow rate of the working fluid supplied from the hydraulic pump 10 to the pressure chamber 231 (232) can be increased, and the steering assist force can be ensured.

  Further, when the current value I2 is in the proper range and the PPS control valve 21 is determined to be normal, and the current value I1 is outside the proper range and the VFC control valve 41 is determined to be abnormal, The process proceeds to step S181. In step S181, the second preliminary control map is referred to based on the vehicle speed value, and the target control duty ratio T2sub is input as the control value of the PPS control valve 21. Thereafter, the process proceeds to step S182, where the PPS control valve 21 is controlled with the new target control duty ratio T2sub, and the energization is stopped to turn off the VFC control valve 41 (duty ratio zero). As described above, when the energization to the VFC control valve 41 is stopped, the valve is closed, so that the discharge flow rate of the hydraulic pump 10 through the VFC control valve 41 is reduced. On the other hand, in step S181 and step S182, based on the second preliminary control map as shown in FIG. 9, the target control duty ratio of the PPS control valve 21 is increased compared to the normal operation of the VFC control valve 41, The valve opening is controlled to be closed and adjusted, and the flow rate supplied to the pressure chamber 231 (232) in the discharge flow rate of the hydraulic pump 10 is increased. Then, the absolute flow rate of the working fluid supplied to the pressure chamber 231 (232) can be increased, and the steering assist force can be ensured.

As described above, the power steering device 1 of the present example has a detection function for detecting the quality of the operation state of the control valves 41 and 21. Further, the control controller 50 is configured to switch the control map for controlling the control valves 41 and 21 when a defective operation state of the control valves 41 and 21 is detected by the detection function. . That is, when a defective operation state of the PPS control valve 21 is detected, the PPS control valve is turned off and the control map applied to the VFC control valve 41 is switched from the main control map to the first preliminary control map. Then, only the valve opening degree of the VFC control valve 41 is controlled based on the first preliminary control map. When a defective operation state of the VFC control valve 41 is detected, the VFC control valve 41 is turned off and the control map applied to the PPS control valve 21 is switched from the main control map to the second preliminary control map. . Then, only the valve opening degree of the PPS control valve 21 is controlled based on the second preliminary control map.
By controlling in this way, even when any one of the control valves 41 and 21 is in a defective operating state, the power steering device 1 can be controlled and the steering assist force can be secured.

Instead of the VFC control valve 41 of this example configured to suppress the discharge flow rate of the hydraulic pump 10 by stopping energization, the VFC control valve configured to increase the discharge flow rate of the hydraulic pump 10 by stopping energization. Can also be used.
In this case, if the energization of the VFC control valve 41 is stopped, the flow rate of the working fluid used for generating the steering assist force in the power cylinder 20 increases, so that the steering assist force becomes excessive particularly at high speeds. There is a fear. Therefore, as the second preliminary control map to be applied to the PPS control valve 21 when the energization to the VFC control valve 41 is stopped, it is preferable to use the control map shown by the one-dot chain line c in FIG. In the second preliminary control map shown by the one-dot chain line c in the figure, the target control duty ratio for the PPS control valve 21 is set smaller than that during normal operation (solid line a in the figure), and the valve opening degree is set. Enlarge. If it does so, the flow rate supplied to the pressure chamber 231 (232) of the power cylinder 20 among the discharge flow rates of the hydraulic pump 10 can be suppressed to reduce the absolute flow rate, and the steering assist force obtained by the power cylinder 20 can be suppressed. Travel stability can be improved.

(Example 2)
In this example, the configuration of the PPS control valve of the first embodiment is changed, and the arrangement of the PPS control valve in the hydraulic circuit is changed. The contents will be described with reference to FIG.
In the hydraulic circuit of this example, a communication path 238 is provided between a pair of pressure chambers of the power cylinder, and the PPS control valve 25 is disposed so as to open and close the communication path 238. That is, the PPS control valve 25 of this example is configured to control the communication state between the pair of pressure chambers of the power cylinder and to bypass a part of the working fluid supplied to one pressure chamber to the other pressure chamber. Has been. And according to the effect | action of this PPS control valve 25, the steering assist force which generate | occur | produces in a power cylinder can be suppressed suitably, and driving | running | working stability can be improved.

  The PPS control valve 25 has substantially the same structure as that shown in FIG. 3 of Patent Document 4, and slides into the valve body 254 and the inner hole 255 of the valve body 254 as shown in FIG. A spool 256 movably inserted and a solenoid 257 are provided. The spool 256 is pressed by the urging force of the spring 258. Therefore, when the energization to the solenoid 257 is stopped, the spool 256 blocks the communication path 238 that communicates between the pair of pressure chambers of the power cylinder. On the other hand, when the solenoid 257 is energized and the spool 256 is sucked against the urging force, the communication path 238 opens through the slit 252.

That is, unlike the PPS control valve of the first embodiment, the PPS control valve 25 of this example shuts off the communication path 238 between the pair of pressure chambers of the power cylinder when the energization is stopped. The steering assist force generated is increased.
For this reason, when any trouble occurs in the PPS control valve 25 of this example, if the energization is stopped, the steering assist force may become excessive particularly during high-speed traveling. Therefore, as the first preliminary control map applied to the VFC control valve when the energization to the PPS control valve 25 is stopped, it is preferable to use the control map shown by the one-dot chain line c in FIG. In the first preliminary control map shown by the one-dot chain line c in the figure, the target control duty ratio for the VFC control valve is set smaller than that during normal operation (solid line a in the figure), and the valve opening is closed and adjusted. To control the discharge flow rate discharged from the hydraulic pump 10 via the VFC control valve. If it does so, the absolute flow volume of the working fluid supplied toward the pressure chamber 231 (232) of the power cylinder 20 can be decreased, and the steering assist force obtained by the power cylinder 20 can be suppressed to improve the running stability.

Patent Document 4 describes a method of controlling the PPS control valve of FIG. 3 only by the steering wheel steering angle and the steering wheel angular velocity regardless of the vehicle speed value. Here, since the combination of the control variables used for the control of the PPS control valve can be selected as appropriate, the PPS control valve 25 of this example can be controlled using only the vehicle speed value as the control variable, as in the first embodiment. Alternatively, the PPS control valve 25 can be controlled using the vehicle speed value, the steering angle and the steering wheel angular speed as control variables.
Other configurations and operational effects are the same as those in the first embodiment.

Explanatory drawing explaining the power steering apparatus in Example 1. FIG. 1 is a side view showing a power steering device in Embodiment 1. FIG. Explanatory drawing explaining the power cylinder and PPS control valve in Example 1. FIG. Sectional drawing which shows the cross-section of the VFC control valve in Example 1. FIG. Sectional drawing which shows the cross-section of the PPS control valve in Example 1. FIG. FIG. 2 is a system block diagram around a control controller according to the first embodiment. The figure explaining the determination map for determining the operation state of a control valve in Example 1. FIG. The graph explaining the control of the VFC control valve with respect to the vehicle speed in Example 1. FIG. The graph explaining the control of the PPS control valve with respect to the vehicle speed in Example 1. FIG. The flowchart figure which shows the control procedure of the power steering apparatus in Example 1. FIG. Sectional drawing which shows the cross-section of the PPS control valve in Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power steering apparatus 10 Hydraulic pump 20 Power cylinder 200 Piston 231, 232 Pressure chamber 21, 25 PPS control valve 30 Servo valve 31 Steering handle 310 Steering angle sensor 40 Flow control mechanism 41 VFC control valve 413 Reservoir tank 50 Control controller 510 Vehicle speed Sensor

Claims (5)

A hydraulic pump that discharges the working fluid; a power cylinder having a piston and a pair of pressure chambers that drive the piston; a first control valve that controls the discharge flow rate of the hydraulic pump ; A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of the throttle, and a second control valve that controls the flow rate of the working fluid that passes through one of the two types of throttles And a hydraulic power steering apparatus including a control controller for controlling the first control valve and the second control valve,
The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Oh it is,
The first control valve is configured to suppress the discharge flow rate when energization is stopped, and the second preliminary control map passes through the one throttle as compared with the main control map. A control map for controlling the second control valve so as to increase the flow rate of the working fluid that generates the steering assist force in the power cylinder of the working fluid by reducing the flow rate of the working fluid;
When the energization stops, the second control valve increases a flow rate ratio of the working fluid that passes through the one throttle and generates a steering assist force in the power cylinder of the working fluid. The first preliminary control map is a control map for controlling the first control valve so as to increase the discharge flow rate as compared with the main control map. A hydraulic power steering device.   A hydraulic pump that discharges a working fluid; a power cylinder having a piston and a pair of pressure chambers that drive the piston; a first control valve that controls a discharge flow rate of the hydraulic pump; A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of the throttle, and a second control valve that controls the flow rate of the working fluid that passes through one of the two types of throttles And a hydraulic power steering apparatus including a control controller for controlling the first control valve and the second control valve,
  The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
  In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
  The first control valve is configured to suppress the discharge flow rate when energization is stopped, and the second preliminary control map passes through the one throttle as compared with the main control map. A control map for controlling the second control valve so as to increase the flow rate of the working fluid that generates the steering assist force in the power cylinder of the working fluid by reducing the flow rate of the working fluid;
  When the energization stops, the second control valve reduces a flow rate ratio of the working fluid that passes through the one throttle, and among the working fluids, a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder. The first preliminary control map is a control map for controlling the first control valve so as to suppress the discharge flow rate as compared with the main control map. A hydraulic power steering device.   A hydraulic pump that discharges a working fluid; a power cylinder having a piston and a pair of pressure chambers that drive the piston; a first control valve that controls a discharge flow rate of the hydraulic pump; A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of the throttle, and a second control valve that controls the flow rate of the working fluid that passes through one of the two types of throttles And a hydraulic power steering apparatus including a control controller for controlling the first control valve and the second control valve,
  The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
  In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
  The first control valve is configured to increase the discharge flow rate when energization is stopped, and the second preliminary control map is configured to pass the one throttle as compared with the main control map. A control map for controlling the second control valve so as to suppress a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder of the working fluid by increasing a flow rate ratio of the working fluid;
  When the energization stops, the second control valve increases a flow rate ratio of the working fluid that passes through the one throttle and generates a steering assist force in the power cylinder of the working fluid. The first preliminary control map is a control map for controlling the first control valve so as to increase the discharge flow rate as compared with the main control map. A hydraulic power steering device.   A hydraulic pump that discharges a working fluid; a power cylinder having a piston and a pair of pressure chambers that drive the piston; a first control valve that controls a discharge flow rate of the hydraulic pump; A servo valve that controls the steering assist force of the power cylinder in accordance with the opening of the throttle, and a second control valve that controls the flow rate of the working fluid that passes through one of the two types of throttles And a hydraulic power steering apparatus including a control controller for controlling the first control valve and the second control valve,
  The control controller includes a memory function storing a control map in which control values for controlling the first control valve and the second control valve are arranged; the first control valve and the second control valve; It has a detection function that detects the quality of the operating state of
  In addition, when it is detected that the operating states of the first control valve and the second control valve are good, the control valves are controlled by the main control map, and the detection function is controlled by the second control valve. Is detected, the control map applied to the first control valve is switched to the first preliminary control map, and the detection function is switched to the first control valve. When a defective operation state of the control valve is detected, the power supply to the first control valve is stopped and the control map applied to the second control valve is switched to the second preliminary control map. Yes,
  The first control valve is configured to increase the discharge flow rate when energization is stopped, and the second preliminary control map is configured to pass the one throttle as compared with the main control map. A control map for controlling the second control valve so as to suppress a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder of the working fluid by increasing a flow rate ratio of the working fluid;
  When the energization stops, the second control valve reduces a flow rate ratio of the working fluid that passes through the one throttle, and among the working fluids, a flow rate ratio of the working fluid that generates a steering assist force in the power cylinder. The first preliminary control map is a control map for controlling the first control valve so as to suppress the discharge flow rate as compared with the main control map. A hydraulic power steering device.   The control controller according to any one of claims 1 to 4, wherein the control controller is configured to perform duty control on the first control valve and the second control valve including electromagnetic valves, and the detection function includes: It is configured to measure a current value energized to the first control valve and the second control valve, and to detect a defective operation state of each control valve based on the measured current value. A hydraulic power steering device.

Images