JP2006015934A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device capable of avoiding an unnecessary increase of flow rate of hydraulic fluid led to a power steering output part after starting an engine. <P>SOLUTION: This device is provided with a flow control valve 9 for adjusting flow rate of the hydraulic fluid led to a power steering output part 8 from a pump 1 driven by the engine 14, and a controller 17 for controlling flow rate QP according to a steering angle θ detected by a steering angle sensor 18 mounted on a vehicle. The controller 17 is provided with a starting time decision means for deciding a starting time of the engine 14, an after starting flow rate regulation means for regulating an increase of the flow rate QP according to the steering angle θ after starting the engine 14, and an after starting flow rate regulation releasing means for releasing the regulation of the flow rate QP by the after starting flow rate regulation means according to a driving condition of the vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a power steering apparatus including a flow control valve that adjusts a flow rate QP of hydraulic fluid guided to a power steering output unit in accordance with a driving condition of a vehicle.

  Conventionally, as an example of this type of power steering device, the one disclosed in Patent Document 1 has a pump that is driven by an engine and discharges hydraulic fluid, and a flow rate QP of hydraulic fluid that is guided from the pump to a power steering output unit. And a flow control valve to be adjusted.

  The flow control valve includes an electromagnetic valve controlled by a controller, and a spool that returns a part of the hydraulic oil to the tank side in response to the operation of the electromagnetic valve, and is supplied to the power steering output unit via the spool. Adjust the hydraulic oil flow rate QP.

  The controller inputs a steering angle signal from the steering angle sensor and a vehicle speed signal from the vehicle speed sensor, calculates a steering angle θ and a steering angular velocity ω from the steering angle signal, and these steering angle θ, steering angular velocity ω, vehicle speed v Is used to estimate the required flow rate QM and control the operation of the flow control valve.

  In this way, by adjusting the flow rate QP supplied to the power steering output unit so as to approach the required flow rate QM, it is possible to suppress supply of wasted hydraulic oil to the power steering output unit, and to reduce the drive loss of the pump. It has become.

Further, since the controller is configured to estimate the required flow rate QM without using the detected value of the steering torque, a torque sensor that directly detects the steering torque is unnecessary, and the cost of the control system can be reduced.
JP 2001-163233 A

  In such a conventional power steering apparatus, the flow rate QP of the hydraulic fluid guided to the power steering output unit is controlled according to the steering angle signal from the steering angle sensor without directly detecting the steering torque. Therefore, the flow rate QP is controlled according to the steering angle θ while the vehicle is stopped immediately after the engine is started and until the steering wheel is turned off by the driver.

  For example, if the driver operates the steering wheel to stop the engine while increasing the steering angle θ, then the engine is started next, even if the steering wheel is not turned off by the driver, depending on the steering angle θ when the vehicle is stopped Since the flow rate QP is increased, not only the driving load of the pump is unnecessarily increased, but also in cold districts, there is a possibility that an oil hammer sound may be generated from the hydraulic piping of the vehicle when warming up.

  The present invention has been made in view of the above problems, and provides a power steering device capable of avoiding an unnecessary increase in the flow rate of hydraulic oil guided to a power steering output unit after engine startup. Objective.

  The present invention relates to a flow control valve that adjusts a flow rate QP of hydraulic fluid guided from a pump driven by an engine to a power steering output unit, and a flow rate according to a steering angle θ detected by a steering angle sensor mounted on the vehicle. The present invention is applied to a power steering device for a vehicle including a controller for controlling QP.

  Then, the controller determines a start time determining means for determining when the engine is started, a post-starting flow restricting means for restricting an increase in the flow rate QP according to the steering angle θ after the engine is started, and a vehicle operating condition. And a post-starting flow rate restriction releasing means for releasing the restriction of the flow rate QP by the post-starting flow rate restricting means.

  According to the present invention, when the controller determines when the engine is started, the flow rate QP of the hydraulic oil is restricted from increasing according to the steering angle θ after the engine is started. As a result, the flow rate QP is unnecessarily increased in accordance with the steering angle θ when the vehicle is stopped after the driver has operated the steering wheel to stop the engine while increasing the steering angle θ and then starts the engine next time. This can reduce the pump driving load and prevent oil hammering noise from being generated from the hydraulic piping of the vehicle during warm-up in a cold district or the like.

  After the engine is started, for example, a driving condition such as steering or driving of the vehicle is determined, and the restriction of the flow rate QP is released. As a result, the controller controls the operation of the flow control valve according to the steering angle θ, and adjusts the flow rate QP of the hydraulic oil guided to the power steering output unit. In this way, the amount of hydraulic oil supplied to the power steering output unit is restored to the required amount, so that an appropriate steering assist force can be obtained and the drive loss of the pump can be kept low.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the power steering device returns the pump 1 driven by the engine 14 mounted on the vehicle and the hydraulic oil discharged from the pump 1 to the tank T side and guides it to the power steering output unit 8. And a flow control valve 9 for adjusting the flow rate QP of the hydraulic oil to be discharged.

  The power steering output unit 8 is steered by a steering valve 15 that controls the flow direction and pressure of hydraulic fluid in accordance with a steering angle and steering torque of a steering wheel (not shown), and hydraulic fluid pressure controlled via the steering valve 15. It is constituted by a power cylinder 16 or the like that applies force. The hydraulic oil discharged from the pump 1 is guided through a steering valve 15 that is switched by operating a steering wheel (steering wheel), flows into one of the power cylinder chambers corresponding to steering, and is connected to the power cylinder 16. A steering assist force is applied to the steering link.

  The flow control valve 9 includes first and second supply passages 5 and 6 that branch the hydraulic oil discharged from the pump 1 in parallel and guide the hydraulic oil to the power steering output unit 8. A valve 60 is interposed, and the rotation speed sensitive valve 3 is interposed in the second supply passage 6.

  The flow control valve 9 includes a flow rate adjusting valve 4 that returns the hydraulic oil in the supply passage 2 to the pump suction side according to the differential pressure across the electromagnetic valve 60 and the rotational speed sensitive valve 3, and the electromagnetic valve 60 and the rotational speed sensitive valve 3. And a relief valve 7 communicating further downstream.

  The flow control valve 9 includes a valve body 21 and a cap 31 as its casing. The valve body 21 has a spool hole 26 into which the spool 11 constituting the flow rate adjusting valve 4 is slidably inserted, a pump port 22 communicating with the discharge side of the pump 1, a return port 23 communicating with the pump suction side, Bypass ports 24, 25, etc. constituting one supply passage 5 are formed. The cap 31 is provided with a supply port 34 constituting the rotation speed sensitive valve 3, a downstream chamber 32 constituting the second supply passage 6, a bypass port 33 constituting the first supply passage 5, and the like.

  In the flow rate adjusting valve 4, a land portion 10 slidably contacting the spool hole 26 is formed on the outer periphery of the spool 11, and when the spool 11 moves to the left in the drawing against the spring 13, the tip of the land portion 10 faces the return port 23. Then, the pump port 22 and the return port 23 are communicated, and the flow rate of the hydraulic oil returned from the pump port 22 to the return port 23 is adjusted according to the sliding position of the spool 11. An upstream pilot pressure chamber 20 is defined at one end of the spool 11, and the upstream pilot pressure chamber 20 communicates with the upstream side of the electromagnetic valve 60 and the rotation speed sensitive valve 3. A downstream pilot pressure chamber 27 having a spring 13 interposed therein is defined at the other end of the spool 11, and the downstream pilot pressure chamber 27 is downstream of the electromagnetic valve 60 and the rotation speed sensing valve 3 through a through hole 28. It communicates with the side. Thus, in the flow rate adjusting valve 4, the differential pressure across the solenoid valve 60 and the rotational speed sensitive valve 3 is guided to both ends of the spool 11, and the spool 11 has the differential pressure across the solenoid valve 60 and the rotational speed sensitive valve 3 and the spring of the spring 13. Move to a position where the forces are balanced.

  The rotation speed sensitive valve 3 includes a supply port 34 interposed in the middle of the second supply passage 6 and a taper rod 12 that changes the opening area of the supply port 34, and the taper rod 12 protrudes from one end of the spool 11. As 12 moves with the spool 11, the opening area of the supply port 34 gradually decreases in a predetermined stroke area. In this way, the flow rate adjusting valve 4 and the rotation speed sensitive valve 3 are linked so that the opening degree of the rotational speed sensitive valve 3 decreases as the opening degree of the flow rate adjusting valve 4 increases.

  When the pump 1 is stopped, the spool 11 is seated on the end surface 38 of the cap 31 in the flow control valve 9 by the biasing force of the spring 13. As a result, the return port 23 is closed by the land portion 10 of the spool 11, the flow rate adjustment valve 4 is fully closed, the spool 11 is seated on the end surface 38 of the cap 31, and the supply port 34 is closed, and the rotation speed sensitive valve 3 is fully closed.

  The electromagnetic valve 60 includes a cylindrical housing 61 that is inserted and attached to the valve body 21 and a shaft 62 that is slidably inserted into a shaft hole 59 on the housing 61 side. The housing 61 is formed with an upstream chamber 64 communicating with the discharge side of the pump 1, a valve hole 66 defining a variable throttle portion between the shaft 62, and a downstream chamber 67 communicating with the power steering output unit 8. . The hydraulic oil discharged from the pump 1 flows through the upstream chamber 64, the valve hole 66, and the downstream chamber 67 to the power steering output unit 8. The shaft 62 is driven in the valve opening direction (upward in FIG. 1) against the spring 68 by electromagnetic force generated in the coil 69.

  The cylindrical shaft 62 has a conical valve body 63 formed at the tip thereof, and the valve body 63 is inserted into the valve hole 66, and the variable orifice 52 is interposed between the valve body 63 of the shaft 62 and the valve. It is formed as an annular gap defined between the holes 66. The opening of the variable orifice 52 is minimized when the coil 69 is in a non-excited state. As the exciting current increases, the shaft 2 is displaced upward in FIG. Gradually grows.

  The electromagnetic valve 60 has a structure in which the core 77 is seated on the stepped portion 78 of the housing 61 and the valve body 63 is slightly separated from the valve hole 66 so that the first supply passage 5 is not fully closed. As a result, the variable orifice 52 is connected to the upstream side and the downstream side of the rotation speed sensitive valve 3 with respect to the supply passage 2, so that the variable orifice 52 can be changed even when a valve stick occurs in which the spool 11 is fixed to the valve body 21 or the cap 31. The hydraulic oil flowing through the orifice 52 bypasses the rotation speed sensitive valve 3 and is supplied to the power steering output unit 8. As a result, a steering assist force can be obtained at the power steering output unit 8, and an excessive load on the pump 1 can be avoided and a fail-safe function can be achieved.

  When the pump 1 is driven by the engine 14 and pressurized hydraulic fluid is supplied to the pump port 22, pressure loss occurs in the valve hole 66 on the electromagnetic valve 60 side and the rotational speed sensing valve 3 through which the hydraulic fluid flows, and both pilot pressures are generated. The spool 11 moves against the spring 13 according to the pressure difference guided to the chambers 20 and 27, and the opening degree between the pump port 22 and the return port 23 is determined at the balance position, and is returned to the return port 23. The flow rate of hydraulic fluid and the flow rate QP of hydraulic fluid supplied to the power steering output unit 8 are adjusted.

  Hereinafter, an operation in which the rotation speed sensitive valve 3 adjusts the flow rate QP of the flow control valve 9 according to the rotation speed of the pump 1 will be described.

  In a state where the pump 1 is rotating in a low speed region, the flow rate adjusting valve 4 and the rotational speed sensitive valve 3 are closed, and the hydraulic oil having a flow rate QP proportional to the rotational speed of the pump 1 is a valve on the electromagnetic valve 60 side. The power steering output unit 8 is supplied through the hole 66.

  When the rotational speed of the pump 1 reaches the middle speed range, the flow rate adjusting valve 4 is opened, and a part of the hydraulic oil flowing into the upstream pilot pressure chamber 20 is returned to the return port 23 as the rotational speed of the pump 1 increases. Since the refrigerant is recirculated, the flow rate QP of the hydraulic fluid supplied to the power steering output unit 8 through the valve hole 66 on the electromagnetic valve 60 side and the rotation speed sensitive valve 3 is kept substantially constant.

  When the rotational speed of the pump 1 further increases, the rotational speed responsive valve 3 causes the tapered rod 12 to move together with the spool 11 to gradually reduce the opening area of the supply port 34, and the flow rate QP of hydraulic oil supplied to the power steering output unit 8. Gradually decreases.

  During the operation of the flow control valve 9, the hydraulic oil that has passed through the valve hole 66 on the electromagnetic valve 60 side and the hydraulic oil that has passed through the rotation speed sensitive valve 3 are merged and supplied to the power steering output unit 8.

  Further, when the controller 17 controls the exciting current of the coil 69 and the opening area of the variable orifice 52 changes, the spool 11 moves against the spring 13 in accordance with the pressure difference introduced to the pilot pressure chambers 20 and 27. The opening degree of the pump port 22 and the return port 23 is determined at the balance position, and the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 is adjusted.

  In this way, the flow control valve 9 moves the spool 11 according to the opening degree of the electromagnetic valve 60, that is, the variable orifice 52 and the opening degree of the rotational speed sensing valve 3, and returns a part of the hydraulic oil discharged from the pump 1 to the return port 23. To the tank T. Since the flow path for returning the hydraulic oil from the return port 23 to the tank T or the suction side of the pump 1 is provided in the valve body 21, the pressure loss is small, and the drive loss on the pump 1 side can be kept low. The fuel consumption of 14 can be reduced.

  The controller 17 receives the steering angle signal from the steering angle sensor 18 and the vehicle speed signal from the vehicle speed sensor 19, calculates the steering angle θ and the steering angular velocity ω from the steering angle signal, and these steering angle θ and steering angular velocity ω. The required flow rate QM is estimated based on the vehicle speed v, and the exciting current of the coil 69 is controlled. As a result, the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 is appropriately adjusted.

  An example of these control block diagrams is shown in FIG. In the controller 17, a table of the steering angle θ and the solenoid current command value I1 is set so that the steering angle θ and the flow rate QP have linear characteristics. Further, a table of the steering angular velocity ω and the solenoid current command value I2 is set so that the steering angular velocity ω and the flow rate QP have linear characteristics. However, when the steering wheel is in the neutral position or in the vicinity thereof, if the steering angle θ and the steering angular velocity ω do not exceed a certain set value, both the command values I1 and I2 are output as zero. The solenoid current command value I1 may be obtained by calculation based on the steering angle θ, and the solenoid current command value I2 may be obtained by calculation based on the steering angular velocity ω.

  The solenoid current command value I5 is output by multiplying the solenoid current command value I1 by the solenoid current command value I3 based on the vehicle speed v. This solenoid current command value I5 is output as 1 as an example when the vehicle speed v is a low speed region, and is output as an example as 0.6 as an example when the vehicle speed v is a low speed region. Output a gradually decreasing value. As a result, the solenoid current command value I1 is output as it is in the low speed range, and the solenoid current command value I1 is 60% in the high speed range. In the middle speed range, if the speed increases, a value inversely proportional to the speed is output.

  The solenoid current command value I4 based on the vehicle speed v is set as a limit value with respect to the solenoid current command value I2, and the solenoid current command value I2 is restricted so as not to exceed the solenoid current command value I4. In this way, the solenoid current command value I4 based on the vehicle speed v is used as a limiter value, and the gradient of the solenoid current command value I6 is kept constant.

  The larger one of the solenoid current command values I5 or I6 obtained in this way is selected. Thus, by selecting only one value, the fluctuation width of the flow rate QP can be suppressed to be small. Control responsiveness can be improved by selecting a large value, not a small value, of the solenoid current command values I5 or I6.

  When a large value is obtained from the solenoid current command value I5 or I6 as described above, the standby solenoid current command value I7 is added thereto. That is, the final solenoid current command value is output as (I5 + I7) or (I6 + I7), and the excitation current is output from the driver to the coil 69.

  In this way, the controller 17 performs control so that the flow rate QP has a linear relationship with respect to the steering angle θ and the steering angular velocity ω, so that the steering sensation matches the output.

  By the way, when the engine 14 is started while maintaining the large steering angle θ while the vehicle is stopped, if the flow rate QP is increased according to the steering angle θ, not only the driving load of the pump 1 is unnecessarily increased, but also in cold regions. In such a case, there is a possibility that an oil hammering sound is generated from the hydraulic piping constituting the supply passage 2 during warm-up. This oil hammer sound is generated when hydraulic fluid that has cooled and becomes highly viscous during parking is supplied from the pump 1 to the power steering output unit 8 through the flow control valve 9 after the engine 14 is started. This is a noise generated by greatly vibrating.

  The present invention copes with this, and the controller 17 determines the starting time of the engine 14 and the flow rate of hydraulic oil supplied to the power steering output unit 8 according to the steering angle θ after the engine 14 is started. A post-start flow restriction means for restricting an increase in QP, and a post-start flow restriction release means for releasing the restriction of the flow quantity QP by the post-start flow restriction means in accordance with operating conditions such as during steering or when the vehicle is running. Shall be provided.

  When the controller 17 determines when the engine 14 is started, the controller 17 restricts an increase in the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 according to the steering angle θ after the engine 14 is started. As a result, the flow rate QP increases in accordance with the steering angle θ when the vehicle is stopped after the driver operates the steering wheel to stop the engine 14 while increasing the steering angle θ and then starts the engine 14 next time. It is possible to reduce the driving load of the pump 1 and to prevent the occurrence of an oil hammer sound from the hydraulic piping of the vehicle when warming up in a cold region or the like.

  After the engine 14 is started, the operating conditions such as steering or traveling of the vehicle are determined, and the restriction of the flow rate QP is released. Thus, the controller 17 controls the operation of the flow control valve 9 in accordance with the steering angle θ, and adjusts the flow rate QP of the hydraulic oil guided to the power steering output unit 8. In this way, the amount of hydraulic oil supplied to the power steering output unit 8 is restored to the required amount, and an appropriate steering assist force can be obtained, and the drive loss of the pump 1 can be kept low.

  As shown in FIG. 2, the controller 17 inputs a signal of the ignition switch 40 of the vehicle as a starting time determination means for determining when the engine 14 is started, and the signal of the ignition switch 40 is switched from OFF to ON. Is detected and it is determined that the engine 14 is being started.

  The ignition switch 40 is one of key switches provided in the vehicle, and is turned on when the engine 14 is operated by the driver and turned off when the engine 14 is stopped.

  It should be noted that a starter switch signal may be used as a start time determining means for determining when the engine 14 is started. The starter switch is one of key switches provided in the vehicle, and is turned on when the engine 14 is cranked by the driver.

  The post-starting flow rate restriction releasing means for releasing the restriction of the flow rate QP at the time of steering is configured to determine when the vehicle is steered and to release the restriction of the flow rate QP by the post-starting flow restriction means at the time of steering.

  Specifically, the controller 17 inputs a steering angular velocity ω calculated by differentiating the steering angle θ obtained from the steering angle signal of the steering angle sensor 18, compares this steering angular velocity ω with a threshold value, and steers the angular velocity. When ω is lower than the threshold value, it is determined that the vehicle is not steered and the flow rate QP continues to be regulated. On the other hand, when the steering angular velocity ω rises above the threshold value, the steering mode is judged and the flow rate QP is released To do. This threshold value is arbitrarily set in the range of 0 to 50 deg / s, for example.

  As a post-starting flow rate restriction releasing means for releasing the restriction of the flow rate QP when the vehicle is running, it is configured to determine when the vehicle is running and to release the restriction of the flow rate QP by the post-starting flow restriction means during the running.

  Specifically, the controller 17 inputs the vehicle speed v obtained from the vehicle speed signal from the vehicle speed sensor 19, compares the vehicle speed v with a threshold value (for example, 0 Km / h), and the vehicle speed v is lower than the threshold value. At the same time, it is determined that the vehicle is stopped, and the restriction of the flow rate QP is continued.

  The flowchart of FIG. 3 shows a routine for controlling the flow rate QP described above, and is executed by the controller 17.

  This will be described. First, in step 1, it is determined whether or not the engine 14 is started when the signal of the ignition switch 40 is switched from OFF to ON. Here, if it is determined that the engine 14 is being started, the process proceeds to step 2 where the start detection flag F is set as F = 1, and then in step 3, each control variable is initialized.

  In the subsequent step 4, detection signals from the steering angle sensor 18 and the vehicle speed sensor 19 are input. In the following step 5, the steering angular velocity ω calculated by differentiating the steering angle θ obtained from the steering angle signal of the steering angle sensor 18 is calculated.

  In step 6, it is determined whether or not the vehicle speed v is lower than a threshold value. In step 7, it is determined whether or not the steering angular velocity ω is lower than the threshold value during non-steering. In step 8, it is determined whether or not the start detection flag F is set.

  Here, if it is determined that the vehicle is at a stop, is not being steered, and the start time detection flag F is set, the routine proceeds to step 9. In step 9, the flow rate QP of hydraulic fluid supplied to the power steering output unit 8 is restricted from increasing according to the steering angle θ after the engine 14 is started.

  On the other hand, if it is determined that the vehicle is traveling or steering, the start time detection flag F is cleared as F = 0 in step 10 and then the process proceeds to step 11. If it is determined in step 8 that the start detection flag F is cleared, the process proceeds to step 11 via step 10. In step 11, the restriction of the flow rate QP is released, and the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 is controlled based on the steering angle θ, the steering angular velocity ω, and the vehicle speed v.

  In other words, after the engine is started, until the vehicle travels or until the steering is performed, the process proceeds to step 9, and the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 increases according to the steering angle θ. On the other hand, once the vehicle travels or is steered, the routine proceeds to step 11 where the restriction of the flow rate QP is released.

  In the control routine, the flow rate QP of the hydraulic oil is controlled in Step 11, but not limited to this, only a command for releasing the restriction of the flow rate QP is output in Step 11, and the steering is performed. Controlling the flow rate QP of the hydraulic fluid supplied to the power steering output unit 8 based on the angle θ, the steering angular velocity ω, and the vehicle speed v is performed in a separate control routine so that the control response of the flow rate QP is improved. May be.

  In the present embodiment, the post-startup flow rate restricting means is configured to suppress the target value of the flow rate QP to a certain limiter value or less. The maximum value of the flow rate QP is set to maxQ, and this limiter value is set to, for example, maxQ / 2.

  FIG. 4 is a characteristic diagram showing how the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 changes according to the steering angle θ.

  During normal operation, the flow rate QP gradually increases from the standby flow rate until reaching the maximum flow rate maxQ as the steering angle θ increases from 0 deg, and is maintained at the maximum flow rate maxQ even when the steering angle θ increases further. .

  On the other hand, when the engine 14 is regulated after starting, the flow rate QP gradually increases from the standby flow rate until the limit value maxQ / 2 is reached as the steering angle θ increases from 0 deg, and the steering angle θ further increases. Is also kept at the limiter value maxQ / 2.

  Thereby, for example, when the engine 14 is started in a state where the steering angle θ exceeds 30 deg, the flow rate QP is restricted to the limiter value maxQ / 2, and the driving load of the pump 1 is reduced, and at the time of warming up in a cold region or the like. It is possible to prevent an oil hammer sound from being generated from the hydraulic piping. When the steering wheel operation is performed in this state, this restriction is released, the flow rate QP returns from the limiter value maxQ / 2 to the maximum flow rate maxQ, and the steering assist force of the power steering output unit 8 is sufficiently secured.

  Even when the flow rate QP is regulated, when the flow rate QP is smaller than the limiter value maxQ / 2, the same flow rate QP as that during normal control can be obtained. The flow rate QP does not change, and there is no response delay for the flow rate QP to return to normal characteristics.

  Next, another embodiment shown in FIG. 5 has a configuration in which the target value of the flow rate QP is reduced by multiplying by a constant gain value d as post-starting flow rate regulating means. When the solenoid current command value I5 based on the steering angle θ and the vehicle speed v is multiplied, a gain value d which is smaller than the solenoid current command value I5 is multiplied to output a solenoid current command value I9. The standby solenoid current command value I7 is added to the current command value I9, and the final solenoid current command value is output as (I7 + I9) at the time of regulation after the engine 14 is started.

  FIG. 6 is a characteristic diagram showing how the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 changes according to the steering angle θ. In this case, the gain value d is set to 0.5 as an example.

  In this case, at the time of regulation after the engine 14 is started, the flow rate QP gradually increases until the steering angle θ increases from 0 deg to 30 deg until the flow rate subjected to gain regulation is reached from the standby flow rate. Even if it becomes larger than this, it is kept at a flow rate subject to gain regulation.

  Thereby, the flow rate QP at the time of regulation after the start of the engine 14 is reduced regardless of the steering angle θ as compared with the flow rate QP at the time of normal operation, thereby reducing the driving load of the pump 1 and at the time of warming up in a cold district or the like. It is possible to prevent an oil hammer sound from being generated from the hydraulic piping.

  Next, another embodiment shown in FIG. 7 is configured to reduce the target value of the flow rate QP to a constant value as the post-starting flow rate regulating means. The final solenoid current command value is output as Iconst at the time of regulation after the engine 14 is started.

  FIG. 8 is a characteristic diagram showing how the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 changes according to the steering angle θ. In this case, the maximum value of the flow rate QP is set to maxQ, and this Iconst is set to, for example, maxQ / 2.

  In this case, at the time of regulation after the engine 14 is started, the flow rate QP is equivalent to the regulated maxQ / 2 regardless of the steering angle θ, preventing oil hammer sound from being generated from the hydraulic piping during warm-up in a cold district or the like. it can.

  Next, another embodiment shown in FIG. 9 outputs the final solenoid current command value as the standby solenoid current command value I7 when the engine 14 is regulated after starting.

  In this case, as shown in FIG. 10, at the time of regulation after the engine 14 is started, the flow rate QP becomes a standby flow rate regardless of the steering angle θ, reduces the driving load of the pump 1, and reduces the hydraulic pressure when warming up in a cold district or the like. It is possible to prevent an oil hammer sound from being generated from the piping.

  Next, other embodiments shown in FIGS. 11 to 14 will be described. A configuration common to these embodiments is to obtain a solenoid current command value I11 based on the steering angle θ and a solenoid current command value I12 based on the steering angular velocity ω, and add both of them. This added value (I11 + I12) is multiplied by a solenoid current command value I13 set based on the vehicle speed v. However, the solenoid current command value I13 based on the vehicle speed v outputs 1 when the vehicle speed is a low speed region, outputs zero when the vehicle speed is high, and has a value after the decimal point from 1 to zero in the middle speed region in the meantime. Output.

  Therefore, if the added value (I11 + I12) is multiplied by the solenoid current command value I13 based on the vehicle speed v, (I11 + I12) is output as it is in the low speed range, and (I11 + I12) becomes zero in the high speed range. In the middle speed range, if the speed increases, a value inversely proportional to the speed is output.

  When (I11 + I12) × I13 is obtained as described above, the standby solenoid current command value I14 is further added thereto. That is, {(I11 + I12) × I13} + I14 is output to the driver as a solenoid current command value.

  The embodiment shown in FIG. 11 has a configuration in which the target value of the flow rate QP is suppressed to a certain limiter value or less as the post-starting flow rate regulating means. The maximum value of the flow rate QP is set to maxQ, and this limiter value is set to, for example, maxQ / 2.

  The embodiment shown in FIG. 12 is configured to reduce the target value of the flow rate QP by multiplying it by a constant gain value d as post-start flow rate restricting means. The solenoid current command value I11 based on the steering angle θ, the steering angular velocity ω, and the vehicle speed v is multiplied by the gain value d to output a solenoid current command value I16, and this solenoid current command value I16 is added to the standby solenoid current command value I14. Is added, and the final solenoid current command value is output as (I16 + I14) at the time of regulation after the engine 14 is started.

  The embodiment shown in FIG. 13 is configured to reduce the target value of the flow rate QP to a constant value as the post-starting flow rate regulating means. The final solenoid current command value is output as Iconst at the time of regulation after the engine 14 is started.

  In the embodiment shown in FIG. 14, the final solenoid current command value is output as the standby solenoid current command value I14 when the engine 14 is regulated after starting.

  As another embodiment, the controller 17 measures an elapsed time T after the engine 14 is started, and power steering according to the steering angle θ until the elapsed time T reaches a timer value T0 (for example, several tens of seconds). While restricting the increase in the flow rate QP of the hydraulic oil supplied to the output unit 8, the restriction on the flow rate QP may be canceled when the elapsed time T has passed the timer value T0 or more.

  The flowchart of FIG. 15 shows a routine for controlling the flow rate QP described above, and is executed by the controller 17.

  Explaining this, first, at step 21, it is determined whether or not the engine 14 is started when the signal of the ignition switch 40 is switched from OFF to ON. If it is determined that the engine 14 is starting, the routine proceeds to step 22 where the starting detection flag F is set as F = 1, the routine proceeds to step 23, the elapsed time T is cleared to T = 0, and the following step At 24, each control variable is initialized.

  In the following step 25, the elapsed time T after starting is measured, and in step 26, it is determined whether or not this elapsed time T has passed the timer value T0.

  If it is determined that the elapsed time T has not passed the timer value T0, it is confirmed in step 27 that the start detection flag F is set, and the process proceeds to step 28. In this step 28, an increase in the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 is regulated in accordance with the steering angle θ after the engine 14 is started.

  On the other hand, if it is determined that the elapsed time T has passed the timer value T0, the start time detection flag F is cleared as F = 0 in step 29, and then the process proceeds to step 30. If it is determined in step 27 that the start detection flag F is cleared, the process proceeds to step 30 via step 29. In step 30, the restriction of the flow rate QP is released, and the flow rate QP of hydraulic fluid supplied to the power steering output unit 8 is controlled based on the steering angle θ, the steering angular velocity ω, and the vehicle speed v.

  That is, the flow rate QP of the hydraulic oil supplied to the power steering output unit 8 according to the steering angle θ regardless of whether the vehicle travels or steers after the engine is started until the timer value T0 elapses. In the meantime, when the timer value T0 elapses, the restriction of the flow rate QP is released.

  As a result, even after the engine 14 is started, the flow rate QP is restricted even in an operation state in which the steering angle θ is large, and the driving load of the pump 1 is reduced, and an oil hammer sound is generated from the hydraulic piping when warming up in a cold region or the like. Can be prevented. When the timer value T0 elapses in this operating state, the restriction of the flow rate QP is released and the flow rate QP increases, but during this time, the pump 1 operates for several tens of seconds, for example, and the temperature of the hydraulic oil rises. It is possible to prevent an oil hammer sound from being generated from the piping.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The present invention can be used in a power steering apparatus including a flow control valve that adjusts a flow rate QP of hydraulic fluid guided to a power steering output unit according to a driving condition of the vehicle.

1 is a system diagram of a power steering apparatus showing an embodiment of the present invention. The block diagram which similarly shows the structure of a controller. The flowchart which similarly shows the control content of a controller. The characteristic view which similarly shows the relationship between a steering angle and the flow volume QP. The block diagram which shows the structure of the controller which shows other embodiment. The characteristic view which similarly shows the relationship between a steering angle and the flow volume QP. The block diagram which shows the structure of the controller which shows other embodiment. The characteristic view which similarly shows the relationship between a steering angle and the flow volume QP. The block diagram which shows the structure of the controller which shows other embodiment. The characteristic view which similarly shows the relationship between a steering angle and the flow volume QP. The block diagram which shows the structure of the controller which shows other embodiment. The block diagram which shows the structure of the controller which shows other embodiment. The block diagram which shows the structure of the controller which shows other embodiment. The block diagram which shows the structure of the controller which shows other embodiment. The flowchart which shows the control content of the controller which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump 2 Supply passage 3 Rotation speed sensitive valve 4 Flow control valve 8 Power steering output part 9 Flow control valve 14 Engine 15 Steering valve 16 Power cylinder 17 Controller 18 Steering angle sensor 60 Solenoid valve

Claims (8)

A flow control valve that adjusts the flow rate QP of hydraulic fluid guided from the pump driven by the engine to the power steering output unit;
In a vehicle power steering apparatus comprising a controller that controls a flow rate QP according to a steering angle θ detected by a steering angle sensor mounted on the vehicle,
The controller includes a start time determining means for determining the start time of the engine,
A post-starting flow rate regulating means for regulating an increase in the flow rate QP according to the steering angle θ after the engine is started;
A power steering device comprising: a post-starting flow rate restriction releasing means for releasing the restriction of the flow rate QP by the post-starting flow rate restricting means according to the driving condition of the vehicle.   2. The power steering according to claim 1, wherein the post-starting flow rate restriction canceling unit is configured to determine when the vehicle is steered and to release the restriction of the flow rate QP by the post-starting flow rate limiting unit during the steering. apparatus.   3. The configuration according to claim 1, wherein the post-starting flow rate restriction canceling unit is configured to determine when the vehicle is running and to release the restriction of the flow rate QP by the post-starting flow rate limiting unit during the travel. Power steering device.   The post-starting flow rate restriction releasing means measures an elapsed time T after starting the engine, determines that the elapsed time T has passed a timer value T0, and releases the restriction of the flow rate QP by the post-starting flow restriction means. The power steering device according to any one of claims 1 to 3, wherein the power steering device is configured as described above.   The power steering apparatus according to any one of claims 1 to 4, wherein the post-starting flow rate restricting unit is configured to suppress a target value of the flow rate QP to be equal to or less than a certain limiter value.   The power steering apparatus according to any one of claims 1 to 4, wherein the post-starting flow rate restricting means is configured to reduce a target value of the flow rate QP by multiplying a constant gain value.   The power steering apparatus according to any one of claims 1 to 4, wherein the post-starting flow rate restricting unit is configured to set a target value of the flow rate QP to a constant value.   8. The power steering apparatus according to claim 7, wherein the post-starting flow rate regulating means is configured to set a target value of the flow rate QP to a standby flow rate.

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