JP2005225344A - Hydraulic power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic power steering system having a superior starting characteristic capable of generating rapidly an appropriate steering assist force after starting operation under a low temperature. <P>SOLUTION: This power steering system 1 comprises a hydraulic pump 10 for discharging a working fluid, a first control valve 41 for adjusting a discharging flow rate of the hydraulic pump 10, a power cylinder 20 for driving a piston, a second control valve 21 for adjusting a flow rate supplied toward the power cylinder 20 of a discharging flow rate of the hydraulic pump 10, and a valve controlling controller 50 for use in controlling each of the control valves 41, 21. This power steering system 1 has a temperature measuring means 63. Then, the valve controlling controller 50 inputs a temperature measured by a temperature sensor 63 before starting the hydraulic pump 10 and at the same time performs a warming-up operation mode in response to this measured temperature. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 an electronic control function.

Conventionally, as a hydraulic power steering device, for example, a piston is fitted and a pair of pressure chambers are provided on both ends of the piston, and a working fluid is supplied to and discharged from the pair of pressure chambers. There is a hydraulic power steering device including a servo valve that performs control (see, for example, Patent Document 1).
In such a hydraulic power steering device, for example, a steering assist force is applied from a piston to a rack shaft that steers a steered wheel, thereby reducing the operation force required for the driver to operate the steering handle. .

JP 61-67664 A

  However, the conventional hydraulic power steering apparatus has the following problems. That is, if the viscosity of the working fluid increases in a low temperature environment, there is a possibility that a sufficient steering assist force cannot be generated in the power cylinder. If the steering assist force is insufficient, the driver may feel that the steering handle operation is heavy, or the steering feeling becomes poor, such as a feeling of catching.

  The present invention seeks to provide a hydraulic power steering apparatus with good start-up characteristics that can generate an appropriate steering assist force quickly after starting at a low temperature.

The present invention relates to a steering shaft coupled to a steering handle, a gear mechanism in which a pinion shaft that transmits rotation of the steering shaft and a rack shaft connected to a steering wheel are gear-engaged, and a hydraulic pump that discharges working fluid A first control valve for adjusting the discharge flow rate of the hydraulic pump, a power cylinder having a piston and a pair of pressure chambers for driving the piston, and supplying the discharge flow rate of the hydraulic pump toward the power cylinder In a hydraulic power steering apparatus including a second control valve for adjusting a flow rate ratio, and a valve control controller for controlling the first control valve and the second control valve,
The hydraulic power steering apparatus has a temperature measuring means for measuring a temperature having a correlation with the temperature of the working fluid,
The valve controller inputs the measured temperature measured by the temperature measuring means before starting the hydraulic pump, and warms up over a predetermined time interval after the hydraulic pump starts according to the measured temperature. The machine operation mode is implemented, and the normal operation mode is implemented after the warm-up operation mode ends,
The warm-up operation mode is a hydraulic power steering device characterized in that the first control valve is controlled so as to increase the discharge flow rate of the hydraulic pump as compared with the normal operation mode. 1).

The hydraulic power steering apparatus of the present invention includes the temperature measuring means for measuring a temperature depending on the temperature of the working fluid. The valve controller inputs the temperature measured by the temperature measuring means before starting the hydraulic pump, and implements the warm-up operation mode according to the measured temperature after starting the hydraulic pump. It is constituted as follows.
Here, as the temperature measuring means, for example, means for measuring the temperature of the engine cooling water, the outside air temperature, the temperature of the lubricating oil of the engine, the temperature of parts or members constituting the automobile, and the like are used. Can do.
In addition, as a method of executing the warm-up operation mode according to the measured temperature, for example, a threshold temperature is set in advance, and the warm-up operation mode is set when the measured temperature is lower than the threshold. A method in which the machine operation mode is carried out and the warm-up operation mode is not carried out in other cases, an implementation time according to the measured temperature, an implementation content (for example, a discharge flow rate of the hydraulic pump, etc.), and the like. There is a method of implementing the warm-up operation mode by changing the above.

  In the hydraulic power steering apparatus, as the warm-up operation mode, the first control valve is controlled to increase the discharge flow rate of the hydraulic pump as compared with the normal operation mode. Here, the normal operation mode is a normal operation mode that is performed after the warm-up operation mode ends for the hydraulic power steering apparatus. That is, the hydraulic power steering apparatus of the present invention has at least a control map or a control formula for implementing the warm-up operation mode in addition to a control map or a control formula for implementing the normal operation mode. ing.

If the first control valve is controlled in the warm-up operation mode and the discharge flow rate is adjusted as described above, the working fluid circulating in the hydraulic power steering device is caused to flow quickly, and the working fluid The temperature can be increased.
Here, the effect of the present invention is particularly effective when the steering handle is operated while the discharge flow rate is increased in the warm-up operation mode. That is, since the working fluid is supplied from the hydraulic pump to the power cylinder, the low-temperature working fluid staying in the pressure chambers (which becomes a factor inhibiting movement of the piston) can be replaced. It is.

  As described above, the hydraulic power steering apparatus of the present invention is configured to implement the warm-up operation mode in which the discharge flow rate of the hydraulic pump is increased at the time of starting at a low temperature. Therefore, in the hydraulic power steering apparatus, the temperature of the working fluid can be quickly raised, and desired characteristics can be obtained quickly even at low temperatures. In addition, when the steering handle is operated during the warm-up operation mode, the low-temperature working fluid retained in each pressure chamber is quickly replaced to quickly achieve the desired steering assist characteristics. can do.

In the present invention, the second control valve is configured to reduce a flow rate supplied from the hydraulic pump toward the power cylinder when the valve opening is increased. In the warm-up operation mode, It is preferable to control the second control valve so that the valve opening becomes smaller than that in the normal operation mode.
In this case, in the warm-up operation mode, the flow rate supplied to the power cylinder can be increased by controlling the opening degree of the second control valve to be small. Therefore, the low-temperature working fluid retained in each pressure chamber can be quickly replaced, and desired characteristics that the power cylinder should exhibit can be realized quickly.

The steering shaft includes a first steering shaft that rotates integrally with the steering handle, and a second steering shaft that rotates integrally with the pinion shaft. The hydraulic power steering device includes: A variable transmission ratio mechanism that makes the rotation transmission ratio between the first steering shaft and the second steering shaft variable using a drive motor including a rotor and a stator;
In the warm-up operation mode, it is preferable to control the drive motor so that the rotation transmission ratio is higher than that in the normal operation mode.
In this case, if the variable transmission ratio mechanism is controlled so that the rotation angle of the pinion shaft is increased, the sliding speed required for the piston can be increased accordingly. In this case, the flow rate of the working fluid supplied from the hydraulic pump to the pressure chamber can be increased, and the working fluid retained in the pressure chamber can be replaced more quickly. The rotation transmission ratio is a value obtained by dividing the rotation angle of the second steering shaft by the rotation angle of the first steering shaft.

Further, it is preferable that the valve controller is configured to calculate a time for performing the warm-up operation mode based on the measured temperature.
In this case, the warm-up operation mode can be appropriately performed according to the measured temperature depending on the outside air temperature.
For example, if the execution time of the warm-up operation mode is lengthened as the measured temperature is lower, the warm-up operation mode can be appropriately performed according to the outside air temperature. In this case, the warm-up operation mode can be finished in a short time after the hydraulic pump is started, and the normal control mode can be entered.

The hydraulic power steering apparatus is applied to a vehicle having an internal combustion engine equipped with an ignition plug and an ignition device for controlling the ignition plug, and the valve control controller has a predetermined rotational speed of the internal combustion engine. When the ignition device is energized before the warm-up operation mode is exceeded, the E / G start mode is used when starting the internal combustion engine in which the rotational speed of the internal combustion engine is equal to or lower than a predetermined rotational speed. In the E / G start mode, it is preferable to control the first control valve so as to suppress the discharge flow rate of the hydraulic pump as compared with the normal operation mode. ).
In this case, if the E / G start mode is performed when starting the internal combustion engine, auxiliary equipment for reducing the power load of the hydraulic pump and starting the internal combustion engine, for example, a starter device Etc. can be reduced. Therefore, the startability of the internal combustion engine is good under the E / G start mode.

  Further, the second control valve is configured such that when the current value to be energized is reduced, the valve opening is increased and the flow rate supplied to the power cylinder is reduced. In the warm-up operation mode, The second control valve is controlled so that the valve opening is smaller than the energization operation mode, and in the E / G start mode, the second control valve is larger than the normal operation mode. Is preferably controlled (claim 6).

In this case, the electric load on the second control valve can be reduced by controlling the valve opening of the second control valve as described above in the E / G start mode. Therefore, under the E / G start mode, the electrical load can be reduced and the startability of the internal combustion engine can be improved.
Further, by controlling the valve opening degree of the second control valve as described above in the warm-up operation mode, the flow rate supplied toward the power cylinder can be increased. Therefore, under the warm-up operation mode, the low-temperature working fluid retained in each pressure chamber can be quickly replaced, and desired characteristics that the power cylinder should exhibit can be realized quickly.

  As the second control valve, it is also possible to use a valve configured such that when the current value to be energized is increased, the valve opening degree is increased and the flow rate supplied to the power cylinder is reduced. In this case, in the E / G start mode, it is preferable to control the second control valve so that the valve opening degree is smaller than that in the normal operation mode and the current value to be energized can be reduced.

The steering shaft includes a first steering shaft that rotates integrally with the steering handle, and a second steering shaft that rotates integrally with the pinion shaft. The hydraulic power steering device includes: A drive motor including a rotor and a stator, a speed reducer that operates by inputting the rotational force of the drive motor, and a lock mechanism that locks or unlocks the rotation of the drive motor are combined, and the speed reducer is interposed. And a variable transmission ratio mechanism that makes the rotation transmission ratio between the first steering shaft and the second steering shaft variable.

In the warm-up operation mode, the drive motor is controlled so that the rotation transmission ratio is higher than in the normal operation mode,
In the E / G start mode, it is preferable to control the lock mechanism so as to lock the rotation of the drive motor.

  In this case, the power load of the drive motor can be reduced by locking the drive motor in the E / G start mode. In the E / G start mode, the electrical load can be reduced and the startability of the internal combustion engine can be improved. Furthermore, for example, if the lock mechanism is configured to lock the drive motor by stopping energization from the viewpoint of fail-safe or the like, the power supplied to the lock mechanism can also be suppressed.

  Further, in the warm-up operation mode, if the variable transmission ratio mechanism is controlled so that the rotation angle of the pinion shaft is increased, the sliding speed required for the piston can be increased accordingly. Therefore, under the warm-up operation mode, the flow rate of the working fluid supplied from the hydraulic pump to the pressure chamber can be increased, and the working fluid staying in the pressure chamber can be replaced more quickly. .

(Example 1)
This example relates to an electronically controlled hydraulic power steering apparatus in which two control valves for flow rate adjustment are provided in a hydraulic circuit to improve the controllability of the steering assist force. This content will be described with reference to FIGS.
As shown in FIG. 1, the power steering device 1 of this example is connected to a steering shaft 32 coupled to a steering handle 31, a pinion shaft 33 that transmits the rotation of the steering shaft 32, and a steering wheel (not shown). A gear mechanism that engages with a rack shaft (not shown), a hydraulic pump 10 that discharges working fluid, a first control valve 41 that adjusts a discharge flow rate of the hydraulic pump 10, a piston 200 (FIG. 6), and A power cylinder 20 having a pair of pressure chambers 231 and 232 (FIG. 6) for driving the piston 200, and a second control valve 21 for adjusting a flow rate ratio supplied to the power cylinder 20 in a discharge flow rate of the hydraulic pump 10. And a valve control controller 50 that controls the first control valve 41 and the second control valve 21.

As shown in FIG. 1, the power steering device 1 of this example includes temperature measuring means 63 (hereinafter referred to as a temperature sensor 63) that measures a temperature having a correlation with the temperature of the working fluid.
The valve controller 50 inputs the temperature measured by the temperature sensor 63 before the hydraulic pump 10 is started, and warms up for a predetermined time interval after the hydraulic pump 10 is started according to the measured temperature. The machine operation mode is implemented, and the normal operation mode is implemented after the warm-up operation mode is completed.
This warm-up operation mode is a mode for controlling the first control valve 41 so as to increase the discharge flow rate of the hydraulic pump 10 as compared with the normal operation mode.
This content will be described in detail below.

  As shown in FIG. 1, 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. A 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.

  As shown in the figure, the power steering device 1 controls the flow rate of the working fluid supplied to the power cylinder 20 among the first control valve 41 that controls the discharge flow rate of the hydraulic pump 10 and the discharge flow rate of the hydraulic pump 10. The second control valve 21 is provided. Furthermore, the power steering apparatus 1 of this example includes a steering angle sensor 310 and a vehicle speed sensor 510, and the valve controller 50 electronically controls the control valves 41 and 21 based on output signals from these sensors. It is configured to control.

The hydraulic pump 10 is a vane type pump as shown in FIG. The drive shaft is connected to an output shaft of a vehicle engine (not shown) via a pulley belt (not shown).
The power cylinder 20 is configured such that the piston 200 (FIG. 6) slides due to a differential pressure between a pair of pressure chambers 231 and 232 (FIG. 6) disposed on both ends.
The servo valve 30 is disposed at the tip 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, as shown in FIG. 1, controls the rotation of the servo valve 30 by the operation torque input to the steering handle 31, and switches the flow path of the working fluid discharged from the hydraulic pump 10 as appropriate. This is a hydraulic type that performs supply / discharge control to the pressure chambers 231 and 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.

  Further, as shown in FIG. 1, the power steering device 1 of the present example includes a variable transmission ratio mechanism 7 that makes the rotation transmission ratio between the steering handle 31 and the pinion shaft 33 variable. As shown in FIG. 2, the variable transmission ratio mechanism 7 includes a steering shaft 32 including a first steering shaft 321 connected to the steering handle 31 and a second steering shaft 322 connected to the pinion shaft 33. Both steering shafts 321 and 322 are connected via a wave gear reducer 79.

As shown in FIG. 2, the variable transmission ratio mechanism 7 inputs the rotation operation of the drive motor 70 to the wave gear reducer 79, thereby transmitting the rotation operation from the first steering shaft 321 to the second steering shaft 322. The rotation transmission ratio at the time can be changed.
Here, as shown in FIG. 3, the wave gear reducer 79 includes a pair of circular splines 791a and 791b having different numbers of teeth, a flex spline 793 meshing with the inner peripheral side of each circular spline 791a and 791b, and the flex spline. And a wave generator 792 fitted to the inner peripheral side of 793.

  In the variable transmission ratio mechanism 7 of this example, as shown in FIGS. 2 and 3, the first steering shaft 321 is configured to rotate integrally with the circular spline 791a via a housing 765. The second steering shaft 322 is configured to rotate integrally with the circular spline 791b. Further, the output shaft 705 of the drive motor 70 fixed inside the housing 765 that rotates integrally with the first steering shaft 321 is press-fitted into a cam 796 that constitutes the wave generator 792 via a driving key 795.

The variable transmission ratio mechanism 7 is configured to drive the drive motor 70 and rotate the wave generator 792, thereby decelerating the rotation and transmitting it to the circular spline 791b.
In the present example, the transmission ratio controller 60 is used to control the drive motor 70 and adjust the rotation transmission ratio of the variable transmission ratio mechanism 7.

  Further, as shown in FIG. 2, the variable transmission ratio mechanism 7 has a resolver 78 adjacent to the drive motor 70 for measuring the rotation angle of the rotor 701, that is, the motor rotation angle. The resolver 78 includes a rotor 781 that rotates integrally with the rotor 701, and a coil 782 that is fixed to the inner periphery of the housing 765 so as to be positioned on the outer periphery side of the rotor 781. The resolver 78 is configured to output an induced current of the coil 782 that changes according to the rotation of the rotor 781 toward the transmission ratio controller 60. In addition, it can replace with the resolver 78 of this example, and can also use the rotation angle sensor using a Hall element.

  Further, as shown in FIG. 2, the variable transmission ratio mechanism 7 of this example includes a lock mechanism 75 that locks or unlocks the relative rotation between the rotor 701 and the stator 702. In the lock mechanism 75, as shown in FIG. 4, a lock lever 72 that rotates about a pin shaft 725 and a lock solenoid 71 that sucks the plunger 710 are disposed on the stator 702 side of the drive motor 70. . A lock plate 742 is disposed on the rotor 701 side so as to rotate integrally with the rotor 701. The lock lever 72 sandwiches the pin shaft 725 and has an action portion 721 that engages with the distal end portion of the plunger 710 and an engagement portion 722 that engages with the outer periphery of the lock plate 74 at both ends thereof. . Further, the lock plate 74 is formed with a concave portion 742 with which the engaging portion 722 is engaged on the outer peripheral portion thereof.

  In the lock mechanism 75, as shown in FIG. 4, a biasing force by a spring (not shown) is acting on the plunger 710 toward the suction reverse direction side. Therefore, when the lock solenoid 710 is not energized, a clockwise rotational force acts on the lock lever 72 around the pin shaft 725. Therefore, the engaging portion 722 of the lock lever 72 is engaged with the concave portion 742 of the lock plate 74, and the relative rotation between the rotor 701 and the stator 702 is locked. When the rotation of the drive motor 70 (FIG. 2) is locked, the first steering shaft 321 and the second steering shaft 322 are directly connected, and the rotation transmission ratio becomes 1.

  On the other hand, when the lock solenoid 71 is energized to attract the plunger 710, the lock lever 72 rotates counterclockwise about the pin shaft 725, and the engaging portion 722 is separated from the outer peripheral portion of the lock plate 74. Therefore, in the lock mechanism 75 of this example, when the lock solenoid 710 is energized, the rotor 701 (FIG. 2) and the stator 702 (FIG. 2) can be rotated relative to each other.

Next, the configuration of the valve controller 50 and the transmission ratio controller 60 will be described. In this example, the valve controller 50 and the transmission ratio controller 60 are connected to an in-vehicle CAN (Control Area Network) network 500 together with a vehicle speed sensor 510 and a steering angle sensor 310 as shown in FIG.
Here, the steering angle sensor 310 is a sensor configured to detect the steering angle of the steering wheel based on a signal output from a rotary encoder (not shown) connected to the steering shaft 32 (FIG. 1). 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. 5, the valve controller 50 includes a one-chip microcomputer 51 incorporating a ROM, a RAM, and a CAN interface, and drive circuits 524 and 522 that drive the control valves 41 and 21 in a duty manner.
The valve controller 50 inputs the vehicle speed, the steering angle, and the temperature measured by the temperature sensor 63 received from the in-vehicle CAN network 500, and duty-controls the control valves 41 and 21 based on these input values. It is constituted as follows. In this example, duty control is performed in which a periodic pulse voltage is applied to the solenoids 419 and 219 so as to continuously control the valve openings of the control valves 41 and 21.

  In the ROM of the valve controller 50 of this example, a first control map group for controlling the control valves 41 and 21 and the variable transmission ratio mechanism 7 under the normal operation mode, and under the warm-up operation mode. A second control map group for controlling the control valves 41 and 21 and the variable transmission ratio mechanism 7 is stored. In the valve controller 50, the control map group used for the control is switched between when the warm-up operation mode is performed and when the normal operation mode is performed. In place of this control map, a control expression for obtaining a control target value from each control variable can be applied. Furthermore, while control is performed using the same control map in the warm-up operation mode and the normal operation mode, a control offset value can be provided in the warm-up operation mode to change a control target value such as a valve opening degree.

As shown in FIG. 5, the transmission ratio controller 60 measures the temperature of the circuit board of the one-chip microcomputer 61 including the ROM, RAM, and CAN interface, the drive circuit 62 that drives the drive motor 70, and the transmission ratio controller 60. And a temperature sensor 63 for the purpose.
The transmission ratio controller 60 is configured to control the drive motor 70 via the drive circuit 62 based on the vehicle speed and steering angle received from the in-vehicle CAN network 500 and the temperature measured by the built-in temperature sensor 63. It is. The transmission ratio controller 60 transmits the measured temperature measured by the temperature sensor 63 to the valve controller 50 via the in-vehicle CAN network 500, and transmits and receives control signals to and from the valve controller 50. It is configured so that it can.

  As shown in FIG. 5, the temperature sensor 63 is a sensor provided to detect heating of the transmission ratio controller 60 and the like. In this example, the temperature sensor 63 is used as the temperature measuring means for measuring the temperature depending on the temperature of the working fluid. As the temperature measuring means, in addition to the temperature sensor 63 of this example, various temperature sensors such as an engine cooling water temperature sensor, an engine lubricating oil temperature sensor, and various temperature sensors used for controlling an air conditioner are used. A temperature sensor can be applied.

  Further, in the power steering apparatus 1 of this example, a hydraulic circuit is configured as shown in FIG. In the figure, the servo of this example in which eight low-speed stops (indicated by L in the figure) and two high-speed stops (indicated by H in the figure) are formed. The valve 30 is expressed as ten stops. In this hydraulic circuit, the working fluid discharged from the hydraulic pump 10 is distributed to the pressure chambers 231 and 232 of the power cylinder 20 after passing through the low speed throttle, and is in a hydraulic circuit branched from the pressure chambers 231 and 232. It flows into the reservoir tank 413 via the high speed throttle and the second control valve 21.

  Here, as shown in FIG. 7, the hydraulic pump 10 of this example is a mechanism for controlling the discharge flow rate as described above, and the flow rate is configured around the first control valve 41 made of an electromagnetic valve. A control mechanism 40 is provided. The flow rate control mechanism 40 receives the working fluid discharged from the hydraulic pump 10 from the inlet 402, returns a part of the working fluid to the reflux path 404 by the action of the spool valve member 406, and supplies the remaining working fluid. It supplies so that it may supply toward the servo valve 30 from the outflow port 403. FIG. Note that a communication passage that opens into the working fluid stored in the reservoir tank 413 is opened in the reflux path 404.

As shown in the figure, the flow 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 integrally formed with a valve body 451. And a first control valve 41 provided with 450.
The throttle member 412 has an opening 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 at an end portion on the valve body 451 side. ing. Further, 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 of the throttle member 412 near the opening port 422. Further, the spool valve member 406 is configured to be biased by the spring 441 and is configured to contact the end portion of the throttle member 412 in a normal original position. The spool valve member 406 blocks communication between the opening port 422 and the reflux path 404 at the original position where the spool valve member 406 contacts the throttle member 412, and when the spool valve member 406 is displaced against the spring 441, the spool port member 406 It is configured to communicate.

As shown in FIG. 7, 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 before and after the variable throttle 405.
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 this example maintains the flow rate discharged from the outflow port 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.

  As shown in FIG. 7, the opening degree of the variable throttle 405 is controlled by the first control valve 41 composed of an electromagnetic valve. The first 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, and at the same time, the valve body 451 is separated from the throttle member 412 and the variable throttle 405 is opened. 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 is closed.

  Therefore, in the flow rate control mechanism 40, as shown in FIG. 7, when the energization of the first control valve 41 is stopped, the variable throttle 405 is closed and a pressure difference before and after the variable throttle 405 is likely to be generated. The flow rate is reduced. On the other hand, when the first control valve 41 is energized, the variable throttle 405 is opened and the pressure difference before and after the variable throttle 405 is suppressed, so that the flow rate discharged from the outlet 403 increases. In addition, it can replace with the 1st control valve 41 which consists of an electromagnetic valve of this example, and it is also possible to apply the control valve comprised so that a valve opening degree can be changed with a stepping motor, for example.

  Further, as described above, in the hydraulic circuit of the power steering apparatus 1 of the present example, as shown in FIG. 6, the second hydraulic pressure path that supplies 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 is connected via the control valve 21. In other words, the second 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 second control valve 21 of the present example allows part of the working fluid supplied from the hydraulic pump 10 toward the pressure chamber 231 (232) to escape to the reservoir tank 413, whereby the pressure in the pressure chamber 231 (232) is reached. It is a valve for adjusting.

  As shown in FIG. 8, the second control valve 21 includes a valve main body 214, a spool 226 slidably inserted into the inner hole 215 of the valve main body 214, and a solenoid 219 that applies a driving force to the spool 226. Have. In the second control valve 21, a first port 213 communicating with the communication path 235 is formed at the tip of the inner hole 215 of the valve body 214. In addition, an annular groove 212 is formed on the inner periphery of the inner hole 215, and the second port 211 through which the communication path 236 communicates opens at four circumferentially spaced positions in the annular groove 212. ing.

  As shown in the figure, 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. A diaphragm is formed. 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.

As shown in FIG. 8, the spool 226 slidably fitted to the inner peripheral surface of the inner hole 215 is pressed against the first port 213 side by the urging force of the spring 218 in the 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, much of the working fluid discharged from the hydraulic pump 10 is bypassed to the reservoir tank 413 via the second control valve 21, and the flow rate supplied to the power cylinder 20 decreases. 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 shortened, and the opening of the variable throttle is reduced. It is. In this case, the flow rate bypassed from the hydraulic pump 10 to the reservoir tank 413 via the second control valve 21 decreases, while the flow rate supplied to the pressure chamber 231 (232) of the power cylinder 20 increases.
In addition, it can replace with the 2nd control valve 21 which consists of an electromagnetic valve of this example, and it is also possible to apply the control valve comprised so that a valve opening degree could be changed with a stepping motor, for example.

A method for controlling the power steering device 1 of the present example configured as described above, in particular, the contents of the warm-up operation mode performed at the time of starting will be described with reference to FIG. Here, the contents of the warm-up operation mode will be described based on the control steps of the valve controller 50.
First, in step S11, when the vehicle ignition is turned on, that is, before the engine is started, the measured temperature TON of the temperature sensor 63 is input.
In step S12, it is determined whether or not the flag value FTON for which an OFF value is set as a default value is an OFF value. When FTON has an OFF value, steps S13 to S15, which are processing routines for determining the execution time tIG of the warm-up operation mode, are performed. On the other hand, when FTON has an ON value, S13 to S15 are performed. Pass.
In step S13, it is determined whether or not the input measured temperature TON is below minus 30 degrees. If TON is less than minus 30 degrees, 10 seconds is set as the execution time tIG in the warm-up operation mode (step S141). Otherwise, zero seconds is set as the execution time tIG (step S142).
In step S15, an ON value is set as the flag value FTON. That is, steps S13 to S15, which are processing routines for calculating the warm-up operation mode execution time tIG, are calculated only once before the engine is started.

  Next, in step S16, the engine speed is input, and it is determined whether or not the engine speed is equal to or greater than a specified speed. If this determination condition is met, step S17 and the subsequent steps are executed. In this example, in order to determine whether or not the engine has been started, 100 rotations are set as the specified rotation speed. Here, when the engine speed is less than the specified speed, that is, when the engine is not started, the engine start mode described in the fourth embodiment can be executed.

In step S17, it is determined whether or not tIG set as the execution time of the warm-up operation mode is zero. In this example, step S18 is repeatedly executed while tIG is a positive value by the combination of step S17 and step S191 for subtracting tIG. On the other hand, when tIG becomes zero, normal control of the power steering apparatus 1 is executed.
Step S18 is a step of controlling the valve opening degree of the first control valve 41 to be larger than that in the normal operation mode and increasing the discharge flow rate of the hydraulic pump 10 from that in the normal operation mode. Further, here, the opening degree of the second control valve 21 is controlled to be smaller than that in the normal operation mode, the rotation transmission ratio by the variable transmission ratio mechanism is higher than that in the normal operation mode, and the steering gear ratio is quick. The drive motor 70 is controlled so as to be on the side.

Here, if the first control valve 41 is controlled as in step S18, the discharge flow rate of the hydraulic pump 10 can be increased, and the temperature can be raised by circulating the working fluid. Further, if the second control valve 21 is controlled as described above, when the steering handle 31 is operated, the flow rate ratio supplied to the pressure chamber 231 (232) in the discharge flow rate can be increased. The low-temperature working fluid retained in the pressure chamber 231 (232) can be replaced. If the low-temperature working fluid staying in the pressure chamber 231 (232) is replaced, the piston 200 can be easily slid, and the low-temperature operation staying inside the other pressure chamber 232 (231) with the sliding. The fluid can be discharged.
Further, in step S18, if the rotation transmission ratio of the variable transmission ratio mechanism 7 is set higher than that in the normal operation mode as described above, the sliding speed of the piston 200 is increased and the operation from the hydraulic pump 10 to the power cylinder 20 is performed. The flow rate of the fluid can be further increased.
In step S192, the power steering device 1 is controlled in the normal operation mode. Here, the opening degrees of the first control valve 41 and the second control valve 21 and the rotation angle of the drive motor 70 constituting the variable transmission ratio mechanism are adjusted based on the vehicle speed, the steering angle, etc.

As described above, the power steering apparatus 1 of the present example is configured to perform the warm-up operation mode when starting at a low temperature. Therefore, in this power steering device 1, the temperature of the working fluid can be quickly raised. Further, in the power steering device 1, when the steering handle 31 is operated during the warm-up operation mode, the replacement of the low-temperature working fluid staying in the pressure chambers 231 and 232 of the power cylinder 20 is promoted. Therefore, the piston 200 quickly shifts to a good sliding state.
Therefore, the power steering apparatus 1 of the present example has excellent start-up characteristics that can quickly realize a good steering feeling at the time of starting at a low temperature.

(Example 2)
This example is an example in which the setting method of the execution time tIG in the warm-up operation mode is changed based on the first embodiment. The contents will be described with reference to FIG.
In this example, as shown in the figure, the execution time tIG of the warm-up operation mode is variably set according to the measured temperature TON. The difference between this example and Example 1 is that the temperature threshold value in Step S13 (FIG. 8) of Example 1 is changed to minus 10 degrees (Step S131), and Step S142 (FIG. 9) is The point is that S143 to S145 are replaced.

Step S131 is a step in which it is determined whether or not the measured temperature TON is minus 10 degrees or more, and if it is less than minus 10, steps S143 to S145 are executed to implement the warm-up operation mode.
Further, in step S143, it is determined whether or not the measured temperature TON is minus 30 degrees or less. If it is minus 30 degrees or less, the execution time tIG in the warm-up operation mode is set to the maximum 10 seconds in step S144. On the other hand, if the temperature exceeds -30 degrees, that is, if the measured temperature TON exceeds -30 degrees and is less than -10 degrees, TON is substituted into the function f in step S145, and the warm-up operation mode implementation time Find tIG.

Other configurations and operational effects are the same as those described in the first embodiment.
Furthermore, in this example, as the function f, a linear function f is set so that tIG changes linearly from 10 seconds to 0 seconds within the temperature range of measured temperature TON = −30 degrees to −10 degrees. did. Instead of the linear function f, a function f as a higher-order function of the second or higher order can be set, and tIG can be changed in a curve within the above temperature range.

(Example 3)
This example is an example in which the setting method of the execution time tIG in the warm-up operation mode is changed based on the first embodiment. The contents will be described with reference to FIG.
In this example, as shown in the figure, the execution time tIG of the warm-up operation mode is variably set according to the measured temperature TON. The difference between the present embodiment and the first embodiment is that each step of steps S13, S141, and S142 (FIG. 9) in the control flow of the first embodiment is replaced with step S134.

Step S134 is a processing step performed using a map that defines the relationship between the measured temperature TON and the warm-up operation mode execution time tIG (shown by a solid line a). Here, based on the measured temperature TON input in step S11, tIG to be set is obtained with reference to the map, and this is set as tIG. According to step S134, the relationship between the measured temperature TON and the warm-up operation mode execution time tIG can be arbitrarily set with a high degree of freedom by appropriately changing the shape of the solid line a.
Other configurations and operational effects are the same as those described in the first embodiment.

Example 4
This example is an example in which the E / G start mode is executed after the ignition is turned on and before the engine is started based on the first embodiment. The contents will be described with reference to FIG.
The E / G start mode described in this example is a mode that is executed when it is determined NO in step S16 of the control flow (FIG. 9) of the first embodiment. FIG. 11 shows control steps of the controller 50 in the E / G start mode.

The control flow shown in the figure is configured to branch from step S16 in the control flow (FIG. 9) of the first embodiment and return to step S17.
Here, it is determined in step S161 whether or not the engine speed has become equal to or higher than the specified speed. Step S162 is repeatedly performed until the rotational speed becomes equal to or higher than the specified rotational speed. As the specified rotational speed, it is preferable to set 100 revolutions that can determine whether or not the engine has started, as in step S16 of the first embodiment.
In step S162, the valve opening of the first control valve 41 is controlled to the minimum valve opening, and the valve opening of the second control valve is controlled to the maximum valve opening. Then, the energization to the drive motor 70 is stopped, and the lock mechanism 75 is controlled to lock the drive motor 70.

If the valve opening of the first control valve 41 is controlled to the minimum valve opening as described above, the discharge flow rate of the hydraulic pump 10 can be suppressed, and the power load of the hydraulic pump 10 using the engine output shaft as a power source can be reduced. . Therefore, it is possible to improve the engine startability by reducing the load on the engine starter (not shown) when the engine is started. Furthermore, when the valve opening of the first control valve 41 is controlled to the minimum valve opening, the current value to be energized can be reduced. Therefore, it is possible to improve the startability of the engine by suppressing the power load at the start of the engine.
Furthermore, the current value to be energized can be reduced by controlling the valve opening of the second control valve 21 to the maximum valve opening as described above. Therefore, it is effective for suppressing the electric power load when starting the engine.

  Further, if the energization to the drive motor 70 is stopped as described above, it is effective for suppressing the power load at the time of starting the engine. Furthermore, according to the lock mechanism 75 configured to lock the drive motor 70 by stopping energization from the viewpoint of fail-safe or the like, the energization to the lock mechanism 75 can be stopped by locking the drive motor 70, The load can be further reduced. When the lock mechanism 75 is locked, the rotation transmission ratio of the variable transmission ratio mechanism 7 becomes 1.

As described above, according to the E / G start mode of this example, it is possible to reduce the power load on the engine output shaft at the time of engine start and to suppress the power load. Therefore, if the E / G start mode of this example is implemented, the startability of the engine can be improved.
Other configurations and operational effects are the same as those described in the first embodiment.

Explanatory drawing explaining the power steering apparatus in Example 1. FIG. Sectional drawing which shows the cross-section of the variable transmission ratio mechanism in Example 1. FIG. Sectional drawing which shows the structure of the wave gear reducer in Example 1 (AA arrow sectional drawing in FIG. 2). The front view which shows the locking mechanism of the drive motor in Example 1 (BB sectional view taken on the line in FIG. 2). 1 is a system block diagram of a control system including a valve controller and a transmission ratio controller in Embodiment 1. FIG. 1 is a circuit diagram showing a hydraulic circuit of a power steering device in Embodiment 1. FIG. Sectional drawing which shows the cross-section of the 1st control valve in Example 1. FIG. Sectional drawing which shows the cross-section of the 2nd control valve in Example 1. FIG. The control flow figure of the valve controller in the warming-up operation mode in Example 1. The control flow figure of the valve controller in the warming-up operation mode in Example 2. FIG. FIG. 10 is a control flow diagram of the valve controller in the warm-up operation mode in the third embodiment. FIG. 10 is a control flow diagram of the valve controller in the E / G start mode in the fourth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power steering apparatus 10 Hydraulic pump 20 Power cylinder 21 2nd control valve 30 Servo valve 32 Steering shaft 40 Flow control mechanism 41 1st control valve 50 Valve control controller 60 Transmission ratio control controller 63 Temperature measurement means (temperature sensor)
7 Variable transmission ratio mechanism 70 Drive motor 75 Lock mechanism

Claims (7)

A steering shaft coupled to the steering handle, a gear mechanism in which a pinion shaft that transmits the rotation of the steering shaft and a rack shaft connected to the steering wheel are in gear engagement, a hydraulic pump that discharges working fluid, and the hydraulic pressure A first control valve that adjusts the discharge flow rate of the pump, a power cylinder having a piston and a pair of pressure chambers that drive the piston, and a flow rate ratio that is supplied to the power cylinder among the discharge flow rates of the hydraulic pump. A hydraulic power steering device including a second control valve that controls the valve control controller that controls the first control valve and the second control valve;
The hydraulic power steering apparatus has a temperature measuring means for measuring a temperature having a correlation with the temperature of the working fluid,
The valve controller inputs the measured temperature measured by the temperature measuring means before starting the hydraulic pump, and warms up over a predetermined time interval after the hydraulic pump starts according to the measured temperature. The machine operation mode is implemented, and the normal operation mode is implemented after the warm-up operation mode ends,
The warm-up operation mode is a mode in which the first control valve is controlled to increase the discharge flow rate of the hydraulic pump as compared with the normal operation mode.   In claim 1, the second control valve is configured to reduce a flow rate supplied from the hydraulic pump toward the power cylinder when the valve opening is increased. In the warm-up operation mode, A hydraulic power steering apparatus, wherein the second control valve is controlled such that the valve opening is smaller than that in a normal operation mode. 3. The hydraulic steering system according to claim 1, wherein the steering shaft includes a first steering shaft that rotates integrally with the steering handle and a second steering shaft that rotates integrally with the pinion shaft. The power steering apparatus includes a variable transmission ratio mechanism in which a rotation transmission ratio between the first steering shaft and the second steering shaft is variable using a drive motor including a rotor and a stator,
In the warm-up operation mode, the drive motor is controlled so that the rotation transmission ratio is higher than that in the normal operation mode.   4. The hydraulic power steering according to claim 1, wherein the valve controller is configured to calculate a time for performing the warm-up operation mode based on the measured temperature. apparatus.   2. The hydraulic power steering device according to claim 1, wherein the hydraulic power steering device is applied to a vehicle having an internal combustion engine including an ignition plug and an ignition device for controlling the ignition plug, and the valve control controller is configured to rotate the internal combustion engine. Prior to executing the warm-up operation mode when the number exceeds the predetermined number of revolutions, when the ignition device is energized, at the start of the internal combustion engine in which the number of revolutions of the internal combustion engine is equal to or less than the predetermined number of revolutions, E / The G start mode is configured to be implemented, and the E / G start mode controls the first control valve so as to suppress the discharge flow rate of the hydraulic pump as compared with the normal operation mode. Hydraulic power steering device.   6. The warm-up operation according to claim 5, wherein the second control valve is configured such that when a current value to be energized is decreased, a valve opening degree is increased and a flow rate supplied to the power cylinder is decreased. In the mode, the second control valve is controlled so that the valve opening is smaller than that in the energization operation mode, and in the E / G start mode, the second opening is larger than in the normal operation mode. 2. A hydraulic power steering apparatus that controls a control valve. 7. The steering shaft according to claim 5, wherein the steering shaft includes a first steering shaft that rotates integrally with the steering handle, and a second steering shaft that rotates integrally with the pinion shaft. The power steering device is a combination of a drive motor including a rotor and a stator, a speed reducer that operates by inputting a rotational force of the drive motor, and a lock mechanism that locks or unlocks the rotation of the drive motor. A variable transmission ratio mechanism in which a rotational transmission ratio between the first steering shaft and the second steering shaft is made variable via a reduction gear;
In the warm-up operation mode, the drive motor is controlled so that the rotation transmission ratio is higher than in the normal operation mode,
In the E / G start mode, the lock mechanism is controlled so as to lock the rotation of the drive motor.

Images