JP2018203202A - Electricity-carrying control device of coil - Google Patents

Abstract

To provide an electricity-carrying control device of a coil which can elongate a life.SOLUTION: A control device 8 comprises a switching element 64 arranged at a power supply line 62 being an electricity-carrying passage to a solenoid coil 41, and a microcomputer 71 for creating a PWM control signal S for turning off the switching element 64. The microcomputer 71 performs assist control for creating the PWM control signal S having a duty ratio based on a vehicle speed V and a steering angle θs according to a traveling state of a vehicle, or standby control for creating the PWM control signal S having a duty ratio at which a flow rate of a working fluid supplied to a hydraulic actuator reaches a prescribed flow rate or smaller. Then, when the vehicle speed V is higher than a middle/high-speed threshold at the execution of the assist control and the standby control, the microcomputer 71 sets a PWM frequency of the created PWM control signal S to a low frequency.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a coil energization control device.

  2. Description of the Related Art Conventionally, there is known a hydraulic power steering device that applies an assist force to a steering mechanism using a hydraulic actuator such as a hydraulic cylinder. Some of these hydraulic power steering devices have a flow control valve in an oil passage between a pump driven by an engine or the like and a hydraulic actuator, and hydraulic oil supplied to the hydraulic actuator according to a vehicle speed, a steering angle, or the like. The fuel consumption is improved by controlling the flow rate (for example, Patent Document 1).

  As described in Patent Document 1, in many cases, a solenoid variable flow valve is used as the flow control valve. Then, the energization control device supplies driving power to the solenoid coil by turning on and off the switching element provided in the energization path by PWM control, and the opening of the solenoid variable flow valve, that is, the flow rate of hydraulic oil supplied to the hydraulic actuator Is controlling.

JP 2013-214693 A

  Incidentally, since the energization control device generates heat by energizing the solenoid coil, the temperature inside the device rises during its operation. And when the temperature of each circuit element in the apparatus rises, the deterioration of each circuit element easily proceeds, leading to a reduction in the life of the apparatus. On the other hand, in recent years, there has been an increasing demand for extending the life of control devices, and there has been a demand for the creation of a technology that can further extend the life.

  In addition, such a request | requirement exists not only in the energization control apparatus of the solenoid coil used for a flow control valve but in the apparatus which controls energization to the coil used for another vehicle-mounted apparatus.

  An object of the present invention is to provide a coil energization control device capable of extending the life.

  A coil energization control device that solves the above problems is a coil that controls energization of a coil of an in-vehicle device mounted on a vehicle, and includes a switching element provided in an energization path to the coil, and the switching A control unit that generates a control signal for turning on and off the element, and when the vehicle speed is higher than a medium high speed threshold value indicating that the vehicle is traveling in a medium high speed range, the vehicle speed is the medium high speed threshold value. The frequency of the generated control signal is set lower than in the following case.

  Here, the cause of heat generation in the energization control device is largely due to switching loss due to on / off of the switching element. This switching loss increases as the switching frequency of the switching element increases, and the amount of heat generated also increases. On the other hand, the higher the switching frequency, the larger the magnetic field generated by the coil, so that the response of the in-vehicle device can be improved, and it is not preferable to simply lower the switching frequency.

  In this regard, the present inventor is able to reduce the switching loss by taking advantage of the characteristics of the switching element. When the vehicle speed is in the middle and high speed range and the vehicle is running stably, the behavior of the vehicle is greatly changed by the driver. Focusing on the fact that such an operation is difficult to perform, and high responsiveness is not required for the in-vehicle device. Therefore, as in the above configuration, the frequency of the control signal generated when the vehicle speed is higher than the medium-high speed threshold is set low, and the switching frequency is lowered, thereby ensuring the necessary responsiveness of the in-vehicle device and switching. Heat generation of the element can be suppressed. As a result, it is possible to extend the life of each component by suppressing the temperature rise inside the control device.

  In the coil energization control device, the in-vehicle device is a flow control valve that controls a flow rate of hydraulic oil supplied from a pump to a hydraulic actuator of a hydraulic power steering device, and the coil adjusts an opening degree of the flow control valve. It is preferable that it is a solenoid coil.

  When the vehicle is traveling in the middle and high speed range, the driver does not steer suddenly, and therefore, high responsiveness is not required for the assist force applied by the hydraulic actuator of the hydraulic power steering device. Therefore, as in the above configuration, the flow rate control valve is a control target, and when the vehicle speed is higher than the medium-high speed threshold, the switching frequency of the switching element that controls the energization to the solenoid coil is lowered, thereby requiring the hydraulic actuator. Heat generation of the switching element can be suppressed while ensuring responsiveness.

  In the coil energization control device, the control unit generates a PWM control signal as the control signal, and the vehicle is in a stop state and a stop and hold condition where the steering wheel is in a hold state, and the vehicle is in a running state. When none of the straight running conditions that are present and straight running are satisfied, the assist control for generating the PWM control signal of the duty ratio based on the vehicle speed and the steering angle of the steering wheel is executed. When the control is executed, when the vehicle speed is higher than the medium high speed threshold, it is preferable to set the PWM frequency of the generated PWM control signal lower than when the vehicle speed is equal to or lower than the medium high speed threshold.

  According to the above configuration, when the vehicle is turning, the opening degree of the flow control valve is adjusted by supplying driving power to the solenoid coil by the PWM control signal having a duty ratio based on the vehicle speed and the steering angle. The flow rate of hydraulic oil supplied to the hydraulic actuator is controlled. As a result, hydraulic oil at a flow rate necessary to generate an appropriate assist force according to the vehicle speed and the steering angle can be suitably supplied to the hydraulic actuator. Further, when the assist control is executed, the switching frequency is lowered when the vehicle speed is higher than the medium-high speed threshold value, so that heat generation of the switching element can be suppressed while suitably ensuring the required responsiveness of the hydraulic actuator.

  In the coil energization control device, the control unit generates a PWM control signal as the control signal, and the vehicle is in a stop state and a stop and hold condition where the steering wheel is in a hold state, and the vehicle is in a running state. When either one of the straight running conditions that are present and the straight running condition is satisfied, standby control that generates the PWM control signal having a duty ratio such that the flow rate of the hydraulic oil supplied to the hydraulic actuator is equal to or less than a predetermined flow rate is performed. When executing the standby control, when the vehicle speed is greater than the medium high speed threshold, the PWM frequency of the PWM control signal to be generated is greater than when the vehicle speed is equal to or less than the medium high speed threshold. Is preferably set low.

  According to the above configuration, the duty ratio PWM is such that the flow rate of the hydraulic oil supplied to the hydraulic actuator is equal to or less than the predetermined flow rate when the vehicle is stopped and maintained or the vehicle is traveling straight. Since the opening degree of the flow control valve is reduced by supplying driving power to the solenoid coil by the control signal, the load on the pump can be reduced. Furthermore, when the standby control is executed, the switching frequency is lowered when the vehicle speed is higher than the medium-high speed threshold, so that heat generation of the switching element can be suppressed while reducing the load on the pump.

  According to the present invention, it is possible to extend the life.

The schematic block diagram of a hydraulic power steering device. The block diagram of a control apparatus. The flowchart which shows the process sequence of PWM control signal generation by a microcomputer.

Hereinafter, an embodiment of a coil energization control device will be described with reference to the drawings.
As shown in FIG. 1, the hydraulic power steering device 1 includes a steering mechanism 4 that steers the steered wheels 3 based on an operation of a steering wheel 2 by a driver, and an assist force that assists the steering mechanism 4 in steering operation. And a hydraulic actuator 5 for providing The hydraulic power steering apparatus 1 includes a pump 6 serving as a supply source of hydraulic oil supplied to the hydraulic actuator 5, a flow control valve 7 that adjusts the flow rate of hydraulic oil supplied from the pump 6 to the hydraulic actuator 5, and flow control. And a control device 8 as a coil energization control device for controlling the operation of the valve 7. The pump 6 of the present embodiment employs an engine-driven pump that is driven by rotation of a crankshaft of an engine (internal combustion engine) 9.

  The steering mechanism 4 includes a steering shaft 11 to which the steering wheel 2 is fixed, and a rack shaft 12 that reciprocates in the axial direction in accordance with the rotation of the steering shaft 11. A pinion shaft 13 that meshes with the rack shaft 12 is provided at the tip portion of the steering shaft 11 so as to be integrally rotatable.

  The rack shaft 12 and the pinion shaft 13 are arranged with a predetermined crossing angle, and the rack teeth 12a formed on the rack shaft 12 and the pinion teeth 13a formed on the pinion shaft 13 mesh with each other. A pinion mechanism 14 is configured. Further, tie rods 15 are connected to both ends of the rack shaft 12, and the tip of the tie rod 15 is connected to a knuckle (not shown) to which the steered wheels 3 are assembled. Therefore, in the hydraulic power steering device 1, the rotation of the steering shaft 11 accompanying the steering operation is converted into the axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckle via the tie rod 15. Thus, the turning angle of the steered wheels 3, that is, the traveling direction of the vehicle is changed.

  The hydraulic actuator 5 includes a hydraulic cylinder 21 that applies an assist force based on hydraulic pressure to the rack shaft 12, and a switching valve 22 that controls supply and discharge of hydraulic oil to and from the hydraulic cylinder 21. The hydraulic cylinder 21 includes a cylindrical cylinder tube 23 through which the rack shaft 12 is reciprocably inserted, and a piston 26 that divides the cylinder tube 23 into a first hydraulic chamber 24 and a second hydraulic chamber 25. Yes. The piston 26 is integrally fixed to the rack shaft 12 so as to be movable in the axial direction.

  The switching valve 22 is configured as a known rotary valve that controls supply and discharge of hydraulic oil to and from the first and second hydraulic chambers 24 and 25 of the hydraulic cylinder 21 in conjunction with the steering operation. Specifically, the switching valve 22 is provided with a supply port 31, a discharge port 32, and first and second supply / discharge ports 33 and 34. The supply port 31 is connected to the flow rate control valve 7 via a supply oil passage 35, and the discharge port 32 is connected to a tank 37 that stores hydraulic oil via a discharge oil passage 36. The first supply / discharge port 33 is connected to the first hydraulic chamber 24 via a first supply / discharge oil passage 38, and the second supply / discharge port 34 is connected to the second hydraulic chamber 25 via a second supply / discharge oil passage 39. It is connected to the. The pump 6 is connected to the tank 37 via the intake oil passage 40.

  A known solenoid variable flow valve is employed as the flow control valve 7. The flow control valve 7 is provided in the middle of the supply oil passage 35. As shown in FIG. 2, the flow control valve 7 includes a solenoid coil 41 and a plunger 42 that protrudes and retracts from the solenoid coil 41 due to a suction force generated by energizing the solenoid coil 41. And the flow control valve 7 changes the opening degree according to the protrusion amount from the solenoid coil 41 of the plunger 42, and controls the flow volume of the hydraulic fluid supplied to the switching valve 22 (hydraulic actuator 5).

  The flow control valve 7 of the present embodiment is configured such that the opening degree increases as the suction force generated by the solenoid coil 41 increases. Further, as shown in FIG. 1, a short loop oil passage 43 connected to the suction oil passage 40 is connected to the flow control valve 7, and the hydraulic oil discharged from the pump 6 is supplied to the hydraulic actuator 5. The portion that is not returned is returned to the suction oil passage 40 via the short loop oil passage 43.

  In the hydraulic power steering apparatus 1 configured as described above, the hydraulic oil sent from the pump 6 via the flow control valve 7 is supplied to the switching valve 22 via the supply oil path 35. The hydraulic oil supplied to the switching valve 22 is supplied to the first and second hydraulic chambers 24, 24 via either one of the first and second oil supply / discharge oil passages 38, 39 according to the steering operation of the driver. 25 is supplied. At this time, hydraulic fluid is discharged from the other of the first and second hydraulic chambers 24, 25, and this hydraulic fluid passes through the other of the first and second supply / discharge oil passages 38, 39, the switching valve 22 and the discharge oil passage 36. To the tank 37. As a result, a hydraulic pressure difference is generated between the first hydraulic chamber 24 and the second hydraulic chamber 25, and the rack shaft 12 moves in the axial direction together with the piston 26 based on the hydraulic pressure difference. Is given to assist the steering operation.

Next, the electrical configuration of the hydraulic power steering apparatus 1 will be described.
Connected to the control device 8 are a vehicle speed sensor 51 that detects the vehicle speed V of the vehicle on which the hydraulic power steering device 1 is mounted, and a steering sensor 52 that detects the steering angle θs of the steering wheel 2. Then, the control device 8 supplies drive power to the solenoid coil 41 based on signals indicating the respective state quantities input from these sensors, thereby supplying the operation of the flow control valve 7, that is, the hydraulic actuator 5. Control the flow rate of hydraulic fluid.

  As shown in FIG. 2, the control device 8 includes a filter circuit 63 provided in a power supply line 62 as an energization path extending from the vehicle-mounted power supply (battery) B through the ignition switch 61, and a filter circuit 63 in the power supply line 62. And a switching element 64 provided on the downstream side. One end of the solenoid coil 41 is connected to the downstream side of the switching element 64 in the power line 62, and the other end of the solenoid coil 41 is installed on the ground. The control device 8 of the present embodiment includes a diode 65 connected in parallel with the solenoid coil 41.

  The filter circuit 63 includes a filter coil 66 connected in series in the middle of the power line 62 and a capacitor 67 connected in parallel to both ends of the filter coil 66, and a direct current supplied from the in-vehicle power supply B Is smoothed. Note that an aluminum electrolytic capacitor is employed for the capacitor 67 of the present embodiment.

  As the switching element 64, a semiconductor switching element whose on / off state is switched by application of a gate voltage, such as a MOSFET (field effect transistor), is used. The switching element 64 has a source terminal connected to the filter circuit 63 and a drain terminal connected to one end of the solenoid coil 41.

  In addition, the control device 8 generates a PWM control signal S as a control signal for controlling the on / off state of the switching element 64 and outputs the PWM control signal S output from the microcomputer 71. And a driver circuit 72 for boosting the voltage. The PWM control signal S output from the microcomputer 71 is a voltage signal that is boosted via the driver circuit 72 and applied to the gate terminal of the switching element 64.

  The microcomputer 71 receives the vehicle speed V and the steering angle θs. The microcomputer 71 receives the actual current value I of the solenoid coil 41 detected by a current sensor 73 provided between the solenoid coil 41 and the ground. The microcomputer 71 calculates a current command value corresponding to a flow rate of hydraulic oil to be supplied to the hydraulic actuator 5 based on the vehicle speed V and the steering angle θs, that is, a target value (target opening) of the opening of the flow control valve 7. The PWM control signal S is generated by executing current feedback control so that the actual current value I follows the current command value. Then, the microcomputer 71 adjusts the opening degree of the flow control valve 7 through power supply to the solenoid coil 41 by turning on and off the switching element 64 based on the PWM control signal S, and supplies the hydraulic oil 5 to the hydraulic actuator 5. Control the flow rate.

  Here, the microcomputer 71 of the present embodiment applies a large assist force by the hydraulic actuator 5 when determining the duty ratio of the PWM control signal S to be generated (ratio between the high level (on) and low level (off) of the voltage). The control mode is switched to one of two control modes of assist control and standby control based on whether or not there is a high necessity for giving. Further, the microcomputer 71 determines the PWM frequency of the PWM control signal S to be generated (the number of times the on / off is switched per unit time), that is, switching of the switching element 64 based on whether or not the hydraulic actuator 5 is required to have high responsiveness. Change the frequency.

  Specifically, the microcomputer 71 does not satisfy any of the stop and hold conditions in which the vehicle is stopped and the steering wheel 2 is in the hold state, and the straight running condition in which the vehicle is in the running state and is in the straight running state. That is, when the vehicle is turning, it is determined that it is highly necessary to apply a large assist force, and assist control is executed. On the other hand, the microcomputer 71 determines that the necessity for applying a large assist force is low and executes standby control when either the stop-holding condition or the straight traveling condition in the straight traveling state is satisfied.

  Specifically, the microcomputer 71 stops and maintains the vehicle speed V when the absolute value of the steering angular velocity ωs obtained by differentiating the steering angle θs is equal to or lower than a predetermined angular velocity ωth. It is determined that the rudder condition is satisfied. The stop state threshold value Vth_0 is a vehicle speed indicating that the vehicle is stopped, and is set to a value slightly larger than zero in consideration of the influence of noise and the like. The predetermined angular velocity is an angular velocity indicating that the steering wheel 2 is being steered, and is set to a value slightly larger than zero in consideration of the influence of noise and the like. The microcomputer 71 determines that the straight traveling condition is satisfied when the vehicle speed V is greater than the stop state threshold value Vth_0 and the absolute value of the steering angle θs is smaller than the predetermined steering angle θth. The predetermined steering angle θth is a steering angle indicating that the steering wheel 2 is in the vicinity of the neutral position and the vehicle is traveling substantially straight, and is set to a small value in the vicinity of zero.

  When executing the assist control, the microcomputer 71 calculates a current command value based on the input vehicle speed V and the steering angle θs, and performs a current feedback calculation so that the actual current value I follows the current command value. The PWM control signal S having such a duty ratio is generated. The microcomputer 71 generates a PWM control signal S based on a large current command value so as to increase the flow rate of hydraulic oil supplied to the hydraulic actuator 5 as the vehicle speed V is slower and the absolute value of the steering angle θs is larger. To do. On the other hand, when the standby control is executed, the microcomputer 71 calculates a current command value so that the flow rate of the hydraulic oil supplied to the hydraulic actuator 5 is equal to or less than a predetermined flow rate, and performs a current feedback calculation. A PWM control signal S having a duty ratio such that the actual current value I follows the current command value is generated. The predetermined flow rate is set to a small flow rate so as to reduce the load applied to the pump 6.

  Further, the microcomputer 71 is required to have high responsiveness in the hydraulic actuator 5 when the vehicle speed V is larger than the medium / high speed threshold value Vth_mh indicating that the vehicle is traveling in a medium / high speed range (for example, a speed range of 40 km / h or higher). It is determined that The medium / high speed threshold value Vth_mh is a speed at which the vehicle speed V is relatively high and the driver does not normally change the traveling direction of the vehicle. Although it can change suitably, it is set to about 50-60 km / h, for example. Then, when executing the assist control and the standby control, the microcomputer 71 sets the PWM frequency of the PWM control signal S to be generated to the preset basic frequency fb when the vehicle speed V is equal to or lower than the medium-high speed threshold Vth_mh. On the other hand, when the vehicle speed V is higher than the medium-high speed threshold Vth_mh, the PWM frequency of the PWM control signal S is set to a low frequency fl lower than the basic frequency fb. Note that the microcomputer 71 of this embodiment sets the PWM frequency of the PWM control signal S based on a clock signal output from a clock (not shown).

Next, a processing procedure for generating the PWM control signal S by the microcomputer 71 will be described.
As shown in the flowchart of FIG. 3, the microcomputer 71 first acquires the vehicle speed V and the steering angle θs, and calculates the steering angular velocity ωs based on the steering angle θs (step 101). Subsequently, it is determined whether or not the vehicle speed V is equal to or less than the stop state threshold Vth_0 (step 102). If the vehicle speed V is equal to or less than the stop state threshold Vth_0 (step 102: YES), the absolute value of the steering angular velocity ωs. Is less than or equal to a predetermined angular velocity ωth (step 103). When the absolute value of the steering angular velocity ωs is equal to or lower than the predetermined angular velocity ωth (step 103: YES), it is determined whether or not the vehicle speed V is greater than the medium / high speed threshold Vth_mh (step 104).

  On the other hand, when the vehicle speed V is larger than the stop state threshold Vth_0 (step 102: NO) and when the absolute value of the steering angular velocity ωs is larger than the predetermined angular velocity ωth (step 103: NO), the microcomputer 71 determines the vehicle speed V. Is greater than the stop state threshold Vth_0 (step 105). Subsequently, when the vehicle speed V is larger than the stop state threshold value Vth_0 (step 105: YES), it is determined whether or not the absolute value of the steering angle θs is smaller than the predetermined steering angle θth (step 106). When the absolute value of θs is smaller than the predetermined steering angle θth (step 106: YES), the routine proceeds to step 104.

  When the vehicle speed V is equal to or lower than the medium-high speed threshold Vth_mh (step 104: NO), the microcomputer 71 sets the duty ratio such that the flow rate of the hydraulic oil supplied to the hydraulic actuator 5 by executing the standby control is equal to or lower than the predetermined flow rate. And a PWM control signal S with the PWM frequency set to the basic frequency fb is generated (step 107). On the other hand, when the vehicle speed V is larger than the medium-high speed threshold value Vth_mh (step 104: YES), it has a duty ratio such that the flow rate of the hydraulic oil becomes equal to or less than a predetermined flow rate by executing the standby control, and the PWM frequency is A PWM control signal S set to the low frequency fl is generated (step 108).

  Further, the microcomputer 71 determines that the vehicle speed V is equal to or less than the stop state threshold value Vth_0 (step 105: NO) and when the absolute value of the steering angle θs is equal to or greater than the predetermined steering angle θth (step 106: NO). It is determined whether it is larger than the medium / high speed threshold value Vth_mh (step 109). When the vehicle speed V is equal to or lower than the medium-high speed threshold Vth_mh (step 109: NO), the duty ratio is such that hydraulic oil having a flow rate based on the vehicle speed V and the steering angle θs is supplied to the hydraulic actuator 5 by executing the assist control. And a PWM control signal S with the PWM frequency set to the basic frequency fb is generated (step 110). On the other hand, when the vehicle speed V is larger than the medium-high speed threshold value Vth_mh (step 109: YES), the hydraulic oil having a flow rate based on the vehicle speed V and the steering angle θs is supplied to the hydraulic actuator 5 by executing the assist control. A PWM control signal S having a high duty ratio and a PWM frequency set to a low frequency fl is generated (step 111).

  The PWM control signal S generated in this way is output from the control device 8, and the switching element 64 is turned on / off at a switching frequency corresponding to the PWM frequency indicated by the PWM control signal S, so that the flow control valve 7 is opened. The hydraulic oil is supplied to the hydraulic actuator 5 in an amount corresponding to the traveling state of the vehicle.

As described above, according to the present embodiment, the following operational effects can be achieved.
(1) The cause of heat generated by the control device 8 is largely due to switching loss caused by turning on and off the switching element 64. This switching loss increases as the switching frequency of the switching element 64 increases, and the amount of heat generation also increases. On the other hand, the higher the switching frequency, the larger the magnetic field generated by the solenoid coil 41. Therefore, the response of the flow control valve 7 can be improved, and it is not preferable to simply lower the switching frequency.

  In this regard, when the vehicle is traveling in the middle / high speed range, the driver usually does not steer suddenly, and therefore, high responsiveness is required for the assist force applied by the hydraulic actuator 5 of the hydraulic power steering device 1. Not. Therefore, as in the present embodiment, when the vehicle speed V is higher than the medium high speed threshold Vth_mh, the PWM frequency of the PWM control signal S to be generated is set low, and the switching frequency is lowered, so that the hydraulic actuator 5 is required. Heat generation of the switching element 64 can be suppressed while suitably ensuring responsiveness. As a result, the temperature rise in the control device 8 is suppressed, so that the life of each component can be extended.

  (2) When the vehicle is turning, the control device 8 supplies driving power to the solenoid coil 41 by the PWM control signal S having a duty ratio based on the vehicle speed V and the steering angle θs, thereby controlling the flow rate control valve 7. The flow rate of hydraulic oil supplied to the hydraulic actuator 5 is controlled. Therefore, when the assist force by the hydraulic actuator 5 is necessary, the hydraulic oil can be suitably supplied. Further, when the assist control is executed, if the vehicle speed V is larger than the medium / high speed threshold Vth_mh, the PWM control signal S with the PWM frequency set to the low frequency fl is generated, so that the required responsiveness of the hydraulic actuator 5 is generated. As a result, heat generation of the switching element 64 can be suppressed.

  (3) The control device 8 is configured so that the flow rate of the hydraulic oil supplied to the hydraulic actuator 5 is less than or equal to a predetermined flow rate when the vehicle is stopped and steered or when the vehicle is traveling straight. Since the opening degree of the flow control valve 7 is reduced by supplying driving power to the solenoid coil 41 by the ratio PWM control signal S, the load on the pump 6 can be reduced. Furthermore, when the standby speed is executed, if the vehicle speed V is greater than the medium-high speed threshold Vth_mh, the PWM control signal S with the PWM frequency set to the low frequency fl is generated, so the load on the pump 6 is reduced. The heat generation of the switching element 64 can be suppressed.

  (4) Since the control device 8 has the filter circuit 63 including the capacitor 67 made of an electrolytic capacitor, the direct current supplied to the solenoid coil 41 can be smoothed and the influence of noise can be reduced. Here, the electrolytic capacitor has a characteristic that when the temperature rises by 10 ° C. according to Arrhenius's law (10 ° C. double rule), the life is shortened to about half, and it is a relatively weak element against heat. Therefore, when the vehicle speed V is larger than the medium-high speed threshold value Vth_mh, the PWM control signal S with the PWM frequency set to the low frequency fl is generated and the switching frequency is lowered, thereby suppressing the temperature rise inside the control device 8. The effect is great.

In addition, the said embodiment can also be implemented in the following aspects which changed this suitably.
In the above embodiment, an engine-driven pump is used as the pump 6, but the present invention is not limited thereto, and for example, a motor-driven electric pump may be used.

  In the above embodiment, an aluminum electrolytic capacitor is used as the capacitor 67 constituting the filter circuit 63. However, the present invention is not limited to this, and an electrolytic capacitor using a metal other than aluminum may be used, and other than an electrolytic capacitor such as a ceramic capacitor. The capacitor may be used. The control device 8 may not have the filter circuit 63.

  In the above embodiment, it is determined that the stop steering condition is satisfied when the vehicle speed V is the stop state threshold Vth_0 or less and the absolute value of the steering angular velocity ωs is the predetermined angular velocity ωth or less. If it can be determined that the vehicle is stopped and the steering is maintained, the parameters used for the determination can be appropriately changed. Similarly, if the state in which the vehicle is traveling straight can be determined, the parameters used for determining whether or not the straight traveling condition is satisfied can be changed as appropriate. Note that the order in which the control device 8 determines whether or not the stop steering condition and the straight traveling condition are satisfied and whether or not the vehicle speed V is greater than the medium-high speed threshold Vth_mh is limited to that shown in the flowchart of FIG. For example, it can be changed as appropriate, for example, by first determining whether or not the straight traveling condition is satisfied.

  In the above embodiment, it is not necessary to determine whether or not the stop steering condition is satisfied or whether or not the straight traveling condition is satisfied. Further, the control device 8 may execute only the assist control without performing both the determination as to whether or not the stop keeping condition is satisfied and the determination as to whether or not the straight traveling condition is satisfied.

  In the above embodiment, when the standby control is executed, the PWM frequency of the PWM control signal S may not be changed depending on whether the vehicle speed V is greater than the medium / high speed threshold value Vth_mh.

-In above-mentioned embodiment, at the time of execution of assist control, it is not necessary to change the PWM frequency of the PWM control signal S according to whether the vehicle speed V is larger than the medium-high speed threshold Vth_mh.
In the above embodiment, the microcomputer 71 generates the PWM control signal S by executing the current feedback control so that the actual current value I follows the current command value. Thus, the PWM control signal S may be generated.

  In the above embodiment, the control device 8 controls the solenoid coil 41 of the flow rate control valve 7. However, the control device 8 is not limited to this. For example, the control device 8 is mounted on a four-wheel drive vehicle and distributes the driving force to the auxiliary drive wheels. A coil used for a driving force transmission device (clutch) to be changed, a motor coil, or the like may be controlled.

  In the above embodiment, the microcomputer 71 uses the PWM control signal as a control signal for controlling the on / off state of the switching element 64, and the PWM frequency is set to the low frequency fl when the vehicle speed V is larger than the medium / high speed threshold Vth_mh. However, the present invention is not limited to this, and other types of control signals may be used as long as the frequency of the control signal for switching the on / off state of the switching element 64 can be changed.

Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.
(A) An energization control device for a coil having a filter circuit including a capacitor made of an electrolytic capacitor. According to the said structure, the drive electric power supplied to a coil can be smoothed and the influence of noise can be reduced. Here, the electrolytic capacitor has a characteristic that when the temperature rises by 10 ° C. according to Arrhenius's law (10 ° C. double rule), the life is shortened to about half, and it is a relatively weak element against heat. Therefore, in the same configuration, when the vehicle speed is larger than the medium-high speed threshold, a low-frequency control signal is generated and the switching frequency of the switching element is lowered, so that the effect of suppressing the temperature rise inside the device is great.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic power steering apparatus, 5 ... Hydraulic actuator, 6 ... Pump, 7 ... Flow control valve, 8 ... Control apparatus, 21 ... Hydraulic cylinder, 22 ... Switching valve, 41 ... Solenoid coil (coil), 42 ... Plunger, 51 DESCRIPTION OF SYMBOLS ... Vehicle speed sensor 52 ... Steering sensor 62 ... Power supply line (energization path) 63 ... Filter circuit 64 ... Switching element 67 ... Capacitor 71 ... Microcomputer (control part), fb ... Fundamental frequency, fl ... Low frequency, S: PWM control signal (control signal), V: vehicle speed, Vth_0: stop state threshold, Vth_mh: medium high speed threshold, θs: steering angle, θth: predetermined steering angle, ωs: steering angular velocity, ωth: predetermined angular velocity.

Claims (4)

A coil energization control device for controlling energization to a coil of an in-vehicle device mounted on a vehicle,
A switching element provided in an energization path to the coil;
A control unit that generates a control signal for turning on and off the switching element,
When the vehicle speed is higher than a medium high speed threshold indicating that the vehicle is traveling in a medium high speed range, the control unit generates a lower frequency for the control signal to be generated than when the vehicle speed is equal to or lower than the medium high speed threshold. Coil energization control device to be set. In the coil energization control device according to claim 1,
The on-vehicle device is a flow rate control valve that controls the flow rate of hydraulic fluid supplied from a pump to a hydraulic actuator of a hydraulic power steering device,
The coil is an energization control device for a coil, which is a solenoid coil for adjusting an opening degree of the flow control valve. In the coil energization control device according to claim 2,
The control unit generates a PWM control signal as the control signal,
When neither the stop-and-hold condition where the vehicle is stopped and the steering wheel is held, or the straight-running condition where the vehicle is in the running state and the straight running state is not satisfied, the vehicle speed and the steering wheel Assist control for generating the PWM control signal with a duty ratio based on the steering angle of
When executing the assist control, if the vehicle speed is larger than the medium-high speed threshold, the coil for setting the PWM frequency of the PWM control signal to be generated lower than the case where the vehicle speed is less than the medium-high threshold. Energization control device. In the coil energization control device according to claim 2 or 3,
The control unit generates a PWM control signal as the control signal,
When the vehicle is in a stopped state and the steering wheel is in the steering-retained condition and the vehicle is in the traveling state and the straight-running condition in which the vehicle is traveling straight, the hydraulic actuator is supplied. Standby control for generating the PWM control signal having a duty ratio such that the flow rate of the operating oil is equal to or less than a predetermined flow rate,
When executing the standby control, if the vehicle speed is greater than the medium high speed threshold value, the coil for setting the PWM frequency of the PWM control signal to be generated lower than when the vehicle speed is less than the medium high speed threshold value. Energization control device.