KR100646445B1 - Electronically controllable power steering apparatus - Google Patents

Abstract

An electronic control power auxiliary steering device of a vehicle is provided to let a driver get huge difference of steering feeling according to a speed change by adjusting the elastic force of an elastic member through a stepping motor and regulating counter force pressure according to maximal pressure of operating oil and vehicle speed. In an electronic control power auxiliary steering device of a vehicle, a pressure control valve comprises a valve body(801) formed with an exhaust port and a supply port(221) at the outer periphery to be shaped hollow inside; a spool(803) communicated with the supply port and formed with a path opened downward inside to slide in the valve body; an elastic member(805) formed at the upper side of the spool; a supporting body(811) formed at the upper side of the elastic member; a sleeve(817) formed at the upper side of the supporting body; and a stepping motor(815) driving the sleeve. A hollow cap(809) connected with the path is formed at the lower part of the spool.

Description

Electronically Controllable Power Steering Apparatus for Automobiles

1 is a block diagram of an electronically controlled power assisted steering device for a vehicle according to the prior art;

Figure 2a is a cross-sectional view showing one side of the flow path switching valve according to the prior art,

Figure 2b is a cross-sectional view showing the other side of the flow path switching valve according to the prior art and one side of the pressure control valve (PCV: Pressure Control Valve),

3 is a cross-sectional view showing an operating state of a pressure control valve when the vehicle runs at a low speed;

4 is a cross-sectional view showing an operating state of a pressure control valve when the vehicle runs at high speed;

5 is a graph showing the relationship between the torque input when the pressure control valve according to the prior art operates and the pressure of the hydraulic oil supplied from the hydraulic pump,

6 is a graph showing a relationship between the pressure (supply pressure) of the hydraulic oil supplied from the hydraulic pump when the pressure control valve according to the related art is operated and the pressure (reaction pressure) of the hydraulic oil operating in the hydraulic reaction force portion,

7 is a configuration diagram showing an electronically controlled power assisted steering device for a vehicle according to a first embodiment of the present invention;

8 is a partially enlarged view of FIG. 7;

9 is a cross-sectional view taken along the line AA ′ of FIG. 8;

10 is a graph showing the relationship between the torque input and the pressure of the hydraulic oil supplied from the hydraulic pump,

11 is a graph showing the relationship between the pressure (supply pressure) of the hydraulic oil supplied from the hydraulic pump and the pressure (reaction pressure) of the hydraulic oil operating in the hydraulic reaction force portion;

12 is a configuration diagram showing an electronically controlled power assisted steering device for a vehicle according to a second embodiment of the present invention;

FIG. 13 is a partially enlarged view of FIG. 12.

<Explanation of symbols for main parts of the drawings>

101: hydraulic pump 103: flow path switching valve

105: working cylinder 107: vehicle speed sensor

109: electronic control device 111: pressure control valve

203: input shaft 205: pinion shaft

207: reaction force plunger 209: hydraulic reaction force

217: solenoid 221: supply port

223: discharge port 224: reaction force port

801: valve body 803: spool

805: elastic member 807: flow path

809: cap 811: support

813: motor shaft 815: stepping motor

817: sleeve 830: valve housing

901: key 903: keyway

1301: eccentric cam

The present invention relates to an electronically controlled power assisted steering device for a motor vehicle. More specifically, by controlling the elastic force of the elastic member by using a stepping motor, the pressure control to adjust the maximum pressure of the hydraulic oil and the reaction force according to the vehicle speed so that the difference in steering feeling transmitted to the driver as the vehicle speed changes is remarkably felt. The present invention relates to an electronically controlled power assisted steering device for a vehicle having a valve.

In general, the steering device of a vehicle is a device for changing the driving direction of the vehicle at the driver's will, and is a device that assists the driver in advancing the vehicle in a desired direction by arbitrarily changing the rotation center of the front wheel of the vehicle. .

On the other hand, when the driver operates the steering wheel of the vehicle, the power assist steering device assists the driver's steering wheel manipulation force by using the power boosting device so that the driving direction of the vehicle can be easily changed with a smaller force. Device.

Such power assisted steering devices are largely classified into hydraulic power assisted steering (HPS) and electric power assisted steering (EPS).

In the hydraulic power assisted steering device, when the hydraulic pump connected to the rotating shaft of the engine supplies the hydraulic oil to the working cylinder connected to the rack bar, the piston of the operating cylinder supplied with the hydraulic fluid moves to assist the steering operation force. It is a device that enables the steering operation with a small force. On the other hand, the electric power assist steering device includes a motor and an electronic control unit (ECU) in a rack bar or column instead of a hydraulic pump and an operation cylinder to assist the operation force by the power of the motor.

Recently, the number of cars equipped with electric power assisted steering is increasing, but most of the cars are still using hydraulic power assisted steering.

If the vehicle is traveling at low speed or at a standstill, a large amount of steering assistance is required because of the high frictional resistance between the tire and the road, but a large steering assist power is required when the car is traveling at high speeds because the frictional resistance between the tire and the road surface is small. This is not necessary. However, since the general hydraulic power assist steering device supplies the same steering assistance power at a low speed or at a high speed, the steering wheel is lighter than necessary at high speed, and thus, steering stability is worse.

In order to solve this problem, an electronically controllable power steering device (ECPS) has been introduced to maintain steering stability at high speed by controlling the supply of steering assistance power according to the driving speed of a vehicle.

1 is a configuration diagram of an electronically controlled power assisted steering apparatus of a vehicle according to the prior art, and FIGS. 2A and 2B are pressure control valves (PCVs) of one side and the other side of a flow path switching valve according to the prior art, respectively It is sectional drawing which shows one side of.

As shown in FIGS. 1 and 2B, the electronically controlled power assisted steering apparatus of a vehicle according to the prior art includes a hydraulic pump 101 driven by an engine (not shown) of a vehicle and a torsion bar 201. The hydraulic oil flow path according to the relative displacement of the hollow input shaft 203, the pinion shaft 205 connected to the input shaft 203 via the torsion bar 201, and the input shaft 203 and the pinion shaft 205. A flow path switching valve 103 for converting the gas, an operation cylinder 105 for supplying steering auxiliary power by the hydraulic oil transmitted from the flow path switching valve 103, a vehicle speed sensor 107 for sensing the speed of the vehicle, and a vehicle speed Hydraulic pressure regulating the relative displacement of the input shaft 203 and the pinion shaft 205 through the electronic control device 109 receiving the electrical signal from the sensor 107 and the reaction force plunger 207 that moves back and forth by the hydraulic pressure. It is provided in the reaction force part 209 and the one side of the flow path switch valve 103. The pressure control valve 111 controls the supply of the hydraulic oil to the hydraulic reaction force unit 209 by the electronic control device 109.

The pressure control valve 111 includes a supply port 221, a discharge port 223, and a reaction force port 224 on the outer circumferential side thereof, and includes a valve body 211 having a hollow shape and an upper portion inside the valve body 211. A spring 213 that is embedded in the spring 213 to apply an elastic force to the spool 215 in a downward direction, and a lower end is supported by the solenoid 217 so that the upper end is supported by the spring 213 and is slidable inside the valve body 211. And a spool 215 having a predetermined depth on the outer circumferential surface but spaced a predetermined distance from each other, and having a first step portion 225 and a second step portion 227 formed to communicate with each other through the flow path 229. And a solenoid 217 that supports the spool 215 from below and is controlled by the electronic control device 109.

In addition, in the electronically controlled power assisted steering apparatus having such a configuration, the steering shaft 115 connected to the steering wheel 113 rotates by the driver operating the steering wheel 113, and the steering shaft ( The input shaft 203 connected to the 115 rotates while causing a relative displacement with the pinion shaft 205, so that hydraulic oil is selectively supplied to the left and right pressure chambers 105a and 105b of the operating cylinder 105, thereby providing a rack bar ( The basic operating principle in which steering assist power is applied to 119 is no different from a general hydraulic power assist steering device.

However, the electronically controlled power assisted steering device is changed in operation according to the speed of the vehicle, which will be described in detail with reference to FIGS. 3 and 4.

3 is a cross-sectional view showing an operating state of a pressure control valve according to the prior art when the vehicle is traveling at a low speed, and FIG. 4 is a cross-sectional view showing an operating state of the pressure control valve according to the prior art when the vehicle is traveling at a high speed. to be.

When the vehicle parks or runs at a low speed, the spool 215 is controlled by the electronic control device 109 receiving the vehicle speed signal detected by the vehicle speed sensor 107 by controlling the solenoid 217 of the pressure control valve 111. This slides upward. In this case, the first stepped portion 225 is moved upward to be spaced apart from the supply port 221 so that the hydraulic oil cannot be delivered to the flow path hole 229. Therefore, since hydraulic oil is not supplied to the hydraulic reaction force portion 209, the reaction force plunger 207 is spaced apart from the input shaft 203, whereby the input shaft 203 can rotate without friction with the reaction force plunger 207. . That is, in this case, since the steering wheel 113 is lighter, the driver feels the same steering feeling as when the general hydraulic power assisted steering device is operated.

However, when the vehicle is traveling at medium speed or high speed, the spool 215 is moved downward by controlling the pressure control valve 111 by the electronic control device 109 receiving the vehicle speed signal detected from the vehicle speed sensor 107. Make it slide. In this case, the first stepped portion 225 is moved downward to communicate with the supply port 221 and thus the hydraulic oil is transmitted to the flow path hole 229. The hydraulic oil passing through the flow path hole 229 is transferred to the hydraulic reaction force through the second step portion 227 and the reaction force port 224. Since the hydraulic oil is supplied to the hydraulic reaction force unit 209 in this way, the reaction force plunger 207 under the pressure of the hydraulic oil is brought into close contact with the input shaft 203, whereby the rotation of the input shaft 203 is controlled by the reaction force plunger 207. Will be. That is, in this case, since the steering wheel 113 becomes heavy, the driver feels a stable steering feeling at high speed unlike when the general hydraulic power assisted steering device is operated.

5 is a graph showing the relationship between the torque input when the pressure control valve according to the prior art is operated and the pressure of the hydraulic oil supplied from the hydraulic pump, Figure 6 is a pressure (supply pressure) and hydraulic pressure of the hydraulic oil supplied from the hydraulic pump It is a graph showing the relationship between the pressure (reaction pressure) of the hydraulic oil operating in the reaction force portion.

As shown in FIGS. 5 and 6, in the electronically controlled power assisted steering apparatus according to the prior art, the reaction force also increases as the vehicle speed increases, and in particular, the rate of increase of the reaction force according to the increase of the vehicle speed is constant.

Therefore, when the increase rate of reaction pressure according to the change of vehicle speed is constant, there is no difference in the steering feeling felt by the driver even if the vehicle speed is changed, so that the driver cannot feel the current driving condition well only by the change of the steering feeling. There was.

Therefore, the present invention has been invented to solve the above problems, by adjusting the elastic force of the elastic member by using a stepping motor by adjusting the maximum pressure of the hydraulic oil and the reaction force according to the vehicle speed, the steering feeling transmitted to the driver according to the change in the vehicle speed The main object of the present invention is to provide an electronically controlled power assisted steering device for a vehicle having a pressure control valve so that the difference between the two is felt remarkably.

In order to achieve the above object, the present invention provides a hydraulic pump driven by an engine of an automobile, a torsion bar having an upper end connected to a steering wheel, a hollow input shaft in which the torsion bar is built, and an input shaft via the torsion bar. A pinion shaft, a flow path switching valve for converting a flow path of hydraulic oil in accordance with a relative displacement of the input shaft and the pinion shaft, an operation cylinder for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve, and the speed of the vehicle. A vehicle speed sensor for detecting a pressure, an electronic control device receiving an electrical signal from the vehicle speed sensor, a hydraulic reaction force regulating relative displacement of the input shaft and the pinion shaft, and supply of hydraulic oil to the hydraulic reaction force portion by the electronic control device. Electronically controlled power assist tank of the vehicle comprising a pressure control valve to control the In the apparatus, the pressure control valve, and the exhaust port and the supply port is formed on the outer peripheral side, respectively, the valve body consisting of a hollow shape; A spool communicating with the supply port and having a flow path opened downward, the spool being slidable inside the valve body; An elastic member provided on an upper side of the spool; A support formed on the elastic member; A sleeve formed on an upper side of the support; And it provides an electronically controlled power assisted steering of a vehicle comprising a stepping motor for driving the sleeve.

In order to achieve the above object, the present invention provides a hydraulic pump driven by an engine of an automobile, a torsion bar having an upper end connected to a steering wheel, a hollow input shaft having the torsion bar embedded therein, and an input shaft via the torsion bar. A pinion shaft connected to the pin, a flow path switching valve for converting a flow path of hydraulic oil in accordance with a relative displacement of the input shaft and the pinion shaft, an operation cylinder for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve, and the vehicle. A vehicle speed sensor for detecting a speed of the vehicle, an electronic control device that receives an electrical signal from the vehicle speed sensor, a hydraulic reaction unit for regulating relative displacement of the input shaft and the pinion shaft, and hydraulic oil to the hydraulic reaction unit by the electronic control unit. Electronically controlled power beam of the vehicle comprising a pressure control valve to control the supply of In the steering apparatus, the pressure control valve, and the exhaust port and the supply port is formed on the outer peripheral side, respectively, the valve body consisting of a hollow shape; A spool communicating with the supply port and having a flow path opened downward, the spool being slidable inside the valve body; An elastic member provided on an upper side of the spool; A support formed on the elastic member; An eccentric cam vertically meeting the support at an upper side of the support; And it provides an electronically controlled power assisted steering device for a vehicle comprising a stepping motor for driving the eccentric cam.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

FIG. 7 is a block diagram illustrating an electronically controlled power assisted steering device for a vehicle according to a first embodiment of the present invention, FIG. 8 is a partial enlarged view of FIG. 7, and FIG. 9 is a sectional view taken along the line AA ′ of FIG. 8.

As shown in FIGS. 7 to 9, the electronically controlled power assisted steering device for a vehicle according to the first embodiment of the present invention includes a hydraulic pump 101 driven by an engine (not shown) of the vehicle, and a torsion bar. Relative displacement of the hollow input shaft 203 into which the 201 is embedded, the pinion shaft 205 connected to the input shaft 203 via the torsion bar 201, and the input shaft 203 and the pinion shaft 205. A flow path switching valve 103 for converting the flow path of the hydraulic oil, an operation cylinder 105 for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve 103, and a vehicle speed sensor for sensing the speed of the vehicle ( The relative displacement of the input shaft 203 and the pinion shaft 205 through the electronic control device 109 receiving the electrical signal from the vehicle speed sensor 107 and the reaction force plunger 207 moving back and forth by hydraulic pressure. On one side of the hydraulic reaction force portion 209 and the flow path switching valve 103 to regulate Is provided, but comprises a pressure control valve 111 for controlling the supply of the hydraulic oil to the hydraulic reaction force unit 209 by the electronic control device (109).

The pressure control valve 111 has a discharge port 223 and a supply port 221 formed on the outer circumferential side, respectively, and communicates with the valve body 801 and the supply port 221 formed in a hollow shape, but opens downward. A spool 803 provided on the inner side of the valve body 801 so as to be slidable inside the valve body 801, an elastic member 805 provided on the upper side of the spool 803, and an elastic member 805. A support 811 formed on the upper side of the support, a sleeve 817 formed on the upper side of the support 811, and a stepping motor 815 for driving the sleeve 817 and built in the valve housing 830. do.

The valve body 801 has a constant cylindrical diameter and a hollow cylindrical shape, and has a supply port 221 and a discharge port 223 on the outer circumferential side. The supply port 221 is a passage through which the hydraulic oil delivered from the hydraulic pump is supplied, and the discharge port 223 is a passage through which the hydraulic oil delivered to the oil tank is discharged.

The spool 803 is cylindrical, and is formed to be slidable inside the valve body 801, and an oil passage 807 communicating with the supply port 221 is formed therein, and the oil passage 807 is the spool 803. It is open to the lower side of the operating oil supplied through the supply port 221 is transmitted to the lower side of the spool 803 via the flow path (807).

The elastic member 805 is interposed between the upper side of the spool 803 and the upper inner side of the valve body 801 to apply the elastic force F to the spool 803 downward in the axial direction. By the way, the value P x A obtained by multiplying the pressure P of the hydraulic oil acting on the spool 803 at the lower side of the spool 803 by the cross-sectional area A of the spool 803 is the elastic force of the first elastic member 805. If larger than (F), the spool 803 moves upward in the axial direction, and in the opposite case, moves downward. As the spool 803 linearly moves in the axial direction according to the pressure of the hydraulic oil, the flow of the hydraulic oil is controlled while the flow path 807 is communicated with or blocked from the supply port 221.

In addition, the hydraulic oil supplied to the lower side of the spool 803 is finally supplied to the hydraulic reaction force unit 209 to control the rotation of the input shaft 203. As described above, the hydraulic oil is operated by the axial linear movement of the spool 803. Pressure is controlled.

That is, when the elastic force of the elastic member 805 is initially set to a constant value, it is possible to control the maximum pressure of the hydraulic oil acting on the lower side of the spool 803.

As the elastic member 805, a spring having a predetermined elastic force is preferably used, but is not limited thereto.

On the other hand, the lower side of the spool 803 is provided with a hollow cap 809 in communication with the flow path 807 so that the spool 803 protrudes from the inside of the valve body 801 by the elastic force of the elastic member 805. It can also be prevented. The cap 809 may be press-fitted into the valve body 801, and may have a male screw and a female screw on the outer circumferential surface of the cap 809 and the inner circumferential surface of the first valve body 801, respectively, for screwing.

The support 811 is provided to support the elastic member 805 on the upper side of the elastic member 805. The elastic member 805 performs linear movement in the axial direction by the upper sleeve 817 and the stepping motor 815. Support). In addition, an O-ring 812 is provided on an outer circumferential surface of the support 811.

The stepping motor 815 is provided above the sleeve 817 to control sliding of the spool 803 through the motor shaft 813 and the sleeve 817. The stepping motor 815 is operated by the electronic control device when the vehicle speed signal is transmitted from the vehicle speed sensor to the electronic control device.

The motor shaft 813 forms a key 901 on the lower outer peripheral surface and is driven by the stepping motor 815.

The sleeve 817 has a hollow shape that is formed coaxially with the motor shaft 813 and has a key groove 903 on the inner circumferential surface of the motor shaft 813 and engaged with the key 901. In addition, male threads are formed on the outer circumferential surface of the sleeve 817 to engage with female threads formed on the inner circumferential surface of the valve housing 830.

Therefore, in the pressure control valve of the electronically controlled power assisted steering apparatus of the automobile according to the first embodiment of the present invention, when the stepping motor 815 is driven, the motor shaft 813 rotates, and the motor is driven by the key 801. The sleeve 817, which is constrained to the shaft 813, slides the lower spool 803 through the support 811 and the elastic member 805 while moving up and down in the axial direction.

That is, when the vehicle is traveling at a low speed, the stepping motor 815 applies a small force to the sleeve 817 and the support 811 so that the elastic force of the elastic member 805 is reduced. In addition, as the elastic force of the elastic member 805 decreases, the spool 803 can move upward in the axial direction, and the oil passage 807 is cut off from the supply port 221 so that the hydraulic oil is supplied to the hydraulic reaction force portion 209 less. do. As a result, the steering wheel is lighter.

On the other hand, when the car is traveling at a high speed, the spool 803 is moved downward in the axial direction, so that the hydraulic fluid is supplied to the hydraulic reaction force unit 209 so that the steering wheel becomes heavy.

FIG. 10 is a graph illustrating a relationship between a torque input when the pressure control valve of the electronically controlled power assisted steering apparatus of the vehicle according to the first embodiment of the present invention operates and a pressure of hydraulic oil supplied from a hydraulic pump. FIG. When the pressure control valve of the electronically controlled power assisted steering apparatus of the automobile according to the first embodiment of the present invention is operated, the pressure (supply pressure) of the hydraulic oil supplied from the hydraulic pump and the pressure of the hydraulic fluid operating in the hydraulic reaction force part (reaction pressure) ) Is a graph showing the relationship between

As shown in FIGS. 10 and 11, when the pressure control valve of the electronically controlled power assisted steering apparatus of the vehicle according to the first embodiment of the present invention is operated, the reaction force increases as the vehicle speed increases. Although not necessarily the case of the present invention, unlike the prior art, the rate of increase of reaction force increases with increasing vehicle speed. Therefore, since the increase rate of the reaction force according to the change in the vehicle speed is changed, the difference in steering feeling felt by the driver becomes remarkable, and thus the driver can feel the current driving state well through the change in the steering feeling.

Operation of the electronically controlled power assisted steering apparatus of the vehicle according to the first embodiment of the present invention having such a configuration is as follows.

First, the electronic control device 109 receiving the vehicle speed signal sensed by the vehicle speed sensor 107 may control the elastic force of the elastic member 805 by controlling the stepping motor 815. As described above, the hydraulic oil supplied through the vehicle speed sensor 107 may be adjusted. The maximum pressure can be adjusted. The electronically controlled power assisted steering apparatus of the vehicle according to the first embodiment of the present invention determines the maximum pressure of the hydraulic oil in this way and at the same time, the pressure of the hydraulic oil transmitted to the hydraulic reaction force unit 209 according to the vehicle speed under the maximum pressure as follows. To control.

When the car parks or runs at a low speed, the spool 803 slides upward. In this case, since the flow path 807 is spaced apart from the supply port 221, the supply of hydraulic oil is cut off and not supplied to the hydraulic reaction force unit 209, so that the reaction force plunger 207 is spaced apart from the input shaft 203. 203 can rotate without friction with reaction force plunger 207. That is, in this case, since the steering wheel 113 is lighter, the driver feels the same steering feeling as when the general hydraulic power assisted steering device is operated.

However, when the vehicle is traveling at medium speed or high speed, the spool 803 is made to slide downward. In this case, the flow path 807 is in communication with the supply port 221, and the hydraulic oil is supplied to the hydraulic reaction force unit 209 accordingly. Since the hydraulic oil is supplied to the hydraulic reaction force unit 209 in this way, the reaction force plunger 207 under the pressure of the hydraulic oil is brought into close contact with the input shaft 203, whereby the rotation of the input shaft 203 is controlled by the reaction force plunger 207. Will be. That is, in this case, since the steering wheel 113 becomes heavy, the driver feels a stable steering feeling at high speed unlike when the general hydraulic power assisted steering device is operated.

FIG. 12 is a configuration diagram illustrating an electronically controlled power assist steering apparatus for a vehicle according to a second exemplary embodiment of the present invention, and FIG. 13 is a partially enlarged view of FIG. 12.

As shown in FIGS. 12 and 13, the electronically controlled power assisted steering device for a vehicle according to the second embodiment of the present invention includes a hydraulic pump 101 driven by an engine (not shown) of a vehicle, and a torsion bar. Relative displacement of the hollow input shaft 203 into which the 201 is embedded, the pinion shaft 205 connected to the input shaft 203 via the torsion bar 201, and the input shaft 203 and the pinion shaft 205. A flow path switching valve 103 for converting the flow path of the hydraulic oil, an operation cylinder 105 for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve 103, and a vehicle speed sensor for sensing the speed of the vehicle ( The relative displacement of the input shaft 203 and the pinion shaft 205 through the electronic control device 109 receiving the electrical signal from the vehicle speed sensor 107 and the reaction force plunger 207 moving back and forth by hydraulic pressure. On one side of the hydraulic reaction force portion 209 and the flow path switching valve 103 to regulate Non doedoe is configured to include a pressure control valve 111 for controlling the supply of hydraulic fluid to the hydraulic reaction force unit 209 by the electronic control device 109.

The pressure control valve 111 has a discharge port 223 and a supply port 221 formed on the outer circumferential side, respectively, and communicates with the valve body 801 and the supply port 221 formed in a hollow shape, but opens downward. A spool 803 provided on the inner side of the valve body 801 so as to be slidable inside the valve body 801, an elastic member 805 provided on the upper side of the spool 803, and an elastic member 805. And a support 811 formed on the upper side of the support, an eccentric cam 1301 that vertically meets the support 811 above the support 811, and a stepping motor 815 driving the eccentric cam 1301. And embedded in the valve housing 830.

The eccentric cam 1301 has an outer circumferential surface in contact with the upper end of the support 811, and surrounds the motor shaft 813 and rotates together with the motor shaft 813 as the stepping motor 815 is driven. Further, since the motor shaft 813 is spaced apart from the center of the cross section of the eccentric cam 1301 by a predetermined distance, the spool 803 slides up and down in the axial direction as the eccentric cam 1301 rotates. As described above, the hydraulic oil supplied to the hydraulic reaction force unit 209 is controlled as the spool 803 slides.

Since the other configurations and operations are the same as those of the first embodiment of the present invention, the same components are denoted by the same reference numerals, and detailed descriptions and descriptions of the operations are omitted.

The above description is merely illustrative of the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential features of the present invention. Accordingly, the embodiments disclosed herein are not intended to limit the present invention but to describe the present invention, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

As described above, according to the present invention, by controlling the elastic force of the elastic member by using a stepping motor, the difference in the steering feeling transmitted to the driver according to the change in the vehicle speed is remarkably controlled by adjusting the maximum pressure of the hydraulic oil and the reaction force according to the vehicle speed. It has the effect of making you feel.

Claims (8)

A hydraulic pump driven by an engine of an automobile, a torsion bar having an upper end connected to a steering wheel, a hollow input shaft having the torsion bar embedded therein, a pinion shaft connected to the input shaft via the torsion bar, the input shaft and the pinion A flow path switching valve for converting the flow path of the hydraulic oil according to the relative displacement of the shaft, an operation cylinder for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve, a vehicle speed sensor for sensing the speed of the vehicle, and the vehicle speed sensor And an electronic control device that receives an electrical signal from the apparatus, a hydraulic reaction force unit regulating relative displacement of the input shaft and the pinion shaft, and a pressure control valve controlling the supply of hydraulic oil to the hydraulic reaction unit by the electronic control unit. In the electronically controlled power assisted steering of a vehicle, The pressure control valve, A discharge port and a supply port are formed on the outer circumference, respectively, and have a hollow body; A spool communicating with the supply port and having a flow path opened downward, the spool being slidable inside the valve body; An elastic member provided on an upper side of the spool; A support formed on the elastic member; A sleeve formed on an upper side of the support; And Stepping motor for driving the sleeve Electronically controlled power assisted steering of a vehicle comprising a. The method of claim 1, An electronically controlled power assisted steering device for a vehicle, characterized in that a hollow cap communicating with the flow path is provided below the spool. The method according to claim 1 or 2, And the elastic member is a spring. The method of claim 3, wherein O-ring (O-ring) is provided on the outer circumferential surface of the support, the electronically controlled power assist steering device for a vehicle. A hydraulic pump driven by an engine of an automobile, a torsion bar having an upper end connected to a steering wheel, a hollow input shaft having the torsion bar embedded therein, a pinion shaft connected to the input shaft via the torsion bar, the input shaft and the pinion A flow path switching valve for converting the flow path of the hydraulic oil according to the relative displacement of the shaft, an operation cylinder for supplying steering auxiliary power by the hydraulic fluid transferred from the flow path switching valve, a vehicle speed sensor for sensing the speed of the vehicle, and the vehicle speed sensor And an electronic control device that receives an electrical signal from the apparatus, a hydraulic reaction force unit regulating relative displacement of the input shaft and the pinion shaft, and a pressure control valve controlling the supply of hydraulic oil to the hydraulic reaction unit by the electronic control unit. In the electronically controlled power assisted steering of a vehicle, The pressure control valve, A discharge port and a supply port are formed on the outer circumference, respectively, and have a hollow body; A spool communicating with the supply port and having a flow path opened downward, the spool being slidable inside the valve body; An elastic member provided on an upper side of the spool; A support formed on the elastic member; An eccentric cam vertically meeting the support at an upper side of the support; And Stepping motor for driving the eccentric cam Electronically controlled power assisted steering of a vehicle comprising a. The method of claim 5, An electronically controlled power assisted steering device for a vehicle, characterized in that a hollow cap communicating with the flow path is provided below the spool. The method according to claim 5 or 6, And the elastic member is a spring. The method of claim 7, wherein An electronically controlled power assisted steering device for a vehicle, characterized in that an O-ring is provided on an outer circumferential surface of the support.

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