JPH04271968A - Power steering device for vehicle - Google Patents

Abstract

PURPOSE:To improve the stability in the straight advance of a vehicle and provide the speed responsive feeling in the straight advance region of a power steering wheel to a driver, by increasing the steering holding power according to the increase of the car speed in the straight advance of a vehicle, in a power steering device for the vehicle. CONSTITUTION:A control valve 8 interlocked with the steering wheel of a vehicle is interposed between a power cylinder device 2 for applying a steering force to the steering wheel of a vehicle and a working oil feeding source 35 for feeding the working oil to the power cylinder device, and a hydraulic reaction force chamber 44 for holding the control valve 8 at a neutral position is installed, and a hydraulic power generating device for generating the hydraulic pressure corresponding to the car speed is installed, and the power cylinder device 2 is held at the neutral position by leading the hydraulic pressure generated by the hydraulic power generating device into the hydraulic reaction force chamber 44.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed-sensitive power steering device used in a vehicle, and more particularly, to a speed-sensitive power steering device that increases the steering force when the vehicle is traveling straight in accordance with the vehicle speed. The present invention relates to a power steering device for a vehicle.

0002

2. Description of the Related Art Speed-sensitive power steering devices used in vehicles include, for example, Japanese Patent Application Laid-open No. 62-1318.
As disclosed in Publication No. 73, a power cylinder device that applies steering force to steering wheels of a vehicle, a hydraulic oil supply source that supplies hydraulic oil to the power cylinder device, and a power cylinder device and hydraulic oil supply. a control valve that is interposed between the power source and the control valve that controls the amount and direction of supply of hydraulic oil to the power cylinder device in conjunction with the steering wheel of the vehicle; It has a pair of hydraulic reaction chambers arranged in the control valve, and when the valve body of the control valve moves, the flow of hydraulic oil from one hydraulic reaction chamber to the other hydraulic reaction chamber is optimized to correspond to the vehicle speed and steering amount. There is a power steering device for a vehicle that controls the steering force during rightward and leftward steering by reducing the amount of power.

According to such a power steering device, since the steering force of the steering wheel increases as the vehicle speed and the amount of steering increase, it is possible to obtain a favorable operational feeling and steering stability for the driver.

0004

[Problems to be Solved by the Invention] The power steering device described above controls the flow of hydraulic oil from one hydraulic reaction force chamber to the other hydraulic reaction force chamber when the valve body of the control valve moves. Since the power steering device controls the steering force when steering in the left direction and the left direction, the power steering device does not work when the steering wheel is not being steered, that is, when the steering wheel is in the neutral position. That is, when the vehicle is traveling straight, the driver must maintain the steering wheel in the neutral position using only his or her own strength, regardless of the speed of the vehicle. Therefore, when the above-described power steering device is applied to a large vehicle that travels at high speed, sufficient straight-line stability cannot necessarily be obtained.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power steering system for a vehicle that controls the steering force during steering to an optimum value, and to increase the steering force when the vehicle is traveling straight in accordance with an increase in vehicle speed. An object of the present invention is to provide a power steering device for a vehicle, which can improve the straight-line stability of the vehicle and also allow the driver to feel the speed sensitivity of the steering wheel in the straight-line range.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the power steering device for a vehicle of the present invention includes a power cylinder device that applies steering force to steering wheels of a vehicle, and a power cylinder device that supplies hydraulic oil to the power cylinder device. A power steering device for a vehicle, in which a control valve interlocked with a steering wheel of a vehicle is interposed between a hydraulic fluid supply source and the control valve controls the amount and direction of hydraulic fluid supplied to a power cylinder device. In addition to providing a hydraulic reaction chamber that uses hydraulic pressure to maintain the control valve in the neutral position, a hydraulic pressure generating device that generates hydraulic pressure corresponding to the vehicle speed is also provided, and the hydraulic pressure generated by this hydraulic pressure generating device is The present invention is characterized in that the power cylinder device is held in a neutral position by introducing pressure into the above-mentioned hydraulic reaction chamber.

By adopting such a configuration, in the power steering device of the present invention, as the vehicle speed increases, the hydraulic pressure in the hydraulic reaction force chamber increases, and as the hydraulic pressure increases, the control valve is moved to the neutral position. Holding power increases. Therefore, a steering force corresponding to the vehicle speed can be obtained from the power steering device, which improves the straight-line stability of the vehicle, and allows the driver to feel the steering wheel's speed sensitivity in the straight-line range.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention. The power steering device 1 has a power cylinder device 2, and a power piston 3 that reciprocates in the CD direction and an end portion of a sector shaft 4 are housed in a casing of the power cylinder device 2. There is a rack 5 on the side of the power piston 3.
is formed, and the rack 5 meshes with pinion teeth 6 formed at the end of the sector shaft 4. The sector shaft 4 is connected to an axle (not shown) of a steering wheel of the vehicle via a pitman arm, a drag link, and a knuckle arm (all not shown). A pair of steering wheels of a vehicle are attached to both ends of the axle via knuckles and king pins (none of which are shown) so as to be swingable in the left-right direction. Therefore, the power piston 3 is C
When the sector shaft 4 rotates by moving in the direction or D direction, the steering wheel of the vehicle rotates to the right or left depending on the direction of rotation of the sector shaft 4.

A worm shaft 7 is rotatably supported in the casing of the power cylinder device 2. The worm shaft 7 extends through the power piston 3. The worm shaft 7 rotates in conjunction with a steering wheel (not shown), thereby controlling the control valve 8.
Switch. In the figure, E indicates a housing space for a steering nut (not shown) that engages with the worm shaft 7.

The control valve 8 is built into the power piston 3, and in FIG. 1, a cross-sectional view taken along the line A-A shows
It is shown separated from the power piston 3. In this embodiment, the control valve 8 is constituted by a hydraulic reaction type spool valve, the spool 9 of which is configured to be coupled to the worm shaft 7 by a spool shaft 10. Therefore, the spool 9 is connected to the valve bore 11 in conjunction with a steering wheel (not shown).
It slides inside and switches the hydraulic path. Spool grooves 12, 13, and 14 are arranged in parallel on the outer peripheral surface of the spool 9, and land portions 15, 16, 17, and 18 are formed on both sides of these spool grooves 12, 13, and 14. Spool 9
There are reaction chambers 19, 2 on both sides of the sliding direction.
0 is formed, the reaction chamber 19 and the spool groove 13 are connected by an oil passage 21, and the reaction chamber 20 and the spool groove 14 are connected by an oil passage 22.
They are connected to each other. On the other hand, the cylinder portion 2 of the control valve 8
3 is formed with a hydraulic oil supply port 24, a hydraulic oil discharge port 25, and hydraulic oil supply/discharge ports 26, 27, and 28, and a reaction port communicating with the reaction chambers 19 and 20. 29 and 30 are formed. The reaction ports 29 and 30 are interconnected by a reaction passage 31, and this reaction passage 31 is equipped with a throttle (not shown) whose opening degree can be adjusted according to the vehicle speed, thereby controlling the sliding movement of the spool 9. can be controlled.

The supply port 24 of the control valve 8 is connected to an oil reservoir 33 via a hydraulic oil supply path 32, and this supply path 32 is provided with a variable orifice 34 and an oil pump 35. The opening degree of the variable orifice 34 is adjusted by an actuator 36 for steering force control, and the actuator 36 is controlled by a computer 37 so that the opening degree of the variable orifice 34 becomes the optimum opening degree corresponding to the vehicle speed. A hydraulic oil supply path 32, an oil reservoir 33, a variable orifice 34, and an oil pump 35 constitute a hydraulic pressure generating device. In the figure, 38 is a vehicle speed sensor for inputting the current vehicle speed to the computer 37, and 39 is a power source for the computer 37. On the other hand, hydraulic oil supply and discharge ports 26 and 28 provided in the control valve 8 are connected to the pressure chamber 2A of the power cylinder device 2 via an oil passage 40 and an oil port 42, and the supply and discharge port 27 is connected to the oil passage. 41 and an oil port 43 to the pressure chamber 2B of the power cylinder device 2. The pressure chambers 2A and 2B are located on both sides of the power piston 3 in the sliding direction.

The spool 9 of the control valve 8 has a reaction
A shaft portion 9A extending in the direction of the chamber 19 is formed, and the shaft portion 9
The tip of A reaches the inside of a hydraulic reaction chamber 44 attached to the valve bore 11 of the control valve 8. Shoulders 9B and 9C are formed at the tip of the shaft portion 9A of the spool 9 so as to face each other, and a pair of spring receivers 45 and 46 are formed on the shaft portion 9A so as to be engaged with the shoulders 9B and 9C. is installed. A compression coil spring 47 is installed between the spring receivers 45 and 46, and the spring receivers 45 and 46 and the compression coil spring 47 are arranged within the hydraulic reaction force chamber 44. In the figure, 48 is a recess for allowing the shaft portion 9A to slide. The hydraulic reaction force chamber 44 is connected to the hydraulic pressure introduction port 44.
A and the variable orifice 3 via the hydraulic oil supply path 32A.
4 and the oil pump 35 is connected to the supply path 32, so that the hydraulic pressure in the hydraulic reaction chamber 44 is controlled by the opening degree of the variable orifice 34.

The operation of the first embodiment will be explained below.

FIG. 1 shows the spool 9 of the control valve 8 in its neutral position. In this state, the steering wheel is in the neutral position, and the hydraulic oil discharged from the oil pump 35 flows into the supply port 24 of the control valve 8 through the variable orifice 34, and also flows into the hydraulic oil supply path 32A.
It passes through and fills the hydraulic reaction chamber 44. The hydraulic oil that has flowed into the supply port 24 of the control valve 8 passes through the gap between the outer circumferential surface of the spool 9 and the valve bore 11 and reaches the discharge port 25. From the discharge port 25, the oil flows through the discharge path 49.
It is returned to the reservoir 33. Therefore, in the illustrated spool neutral position, the power piston 3 of the power cylinder device 2 does not operate, and the power cylinder device 2 does not apply steering force to the steering wheels of the vehicle.

As described above, when the spool 9 of the control valve 8 is in the neutral position, the steering wheel is also in the neutral position, and the vehicle is in a state of traveling straight. When the vehicle is running in this state and its running speed is low, the actuator 36 increases the opening degree of the variable orifice 34 in accordance with instructions from the computer 37, thereby reducing the hydraulic pressure in the hydraulic reaction chamber 44. Therefore, when the vehicle is running at low speed, the hydraulic pressure in the hydraulic reaction force chamber 44 does not become a large resistance force to the sliding of the spool 9, and the spool 9 slides in conjunction with the steering of the steering wheel, and the power cylinder device 2 Controls the supply and discharge of hydraulic oil to the Control valve 8 when the steering wheel is turned to the right or left
The operation of the power cylinder device 2 and the operation of the power cylinder device 2 are similar to those disclosed in the above-mentioned Japanese Patent Laid-Open No. 131873/1983.

Next, in the illustrated state, as the traveling speed of the vehicle increases, the actuator 36 gradually narrows the opening degree of the variable orifice 34 in accordance with instructions from the computer 37. Therefore, as the vehicle speed increases, the hydraulic pressure within the hydraulic reaction force chamber 44 gradually increases, and the hydraulic pressure within the hydraulic reaction force chamber 44 acts as resistance to the sliding movement of the spool 9. That is, when the vehicle is running at high speed, the hydraulic pressure in the hydraulic reaction force chamber 44 increases, so there is a force to maintain the spool 9 in the neutral position, in other words, when the steering wheel is steered to the right or left. The force required at the start of steering (hereinafter referred to as steering force) increases in accordance with the vehicle speed. This improves the straight-line stability of the vehicle and allows the driver to feel the steering wheel's speed sensitivity in the straight-line range.

FIG. 4 shows the relationship between the steering force F and the steering angle Θ in the first embodiment. In the figure, Fo is the steering force,
Further, Θo indicates play in the steering angle of the steering wheel. From the figure, it can be seen that the steering wheel holding force Fo increases as the vehicle speed increases. FIG. 3 shows the relationship between the steering force F and the steering angle Θ of the power steering device disclosed in the above-mentioned Japanese Patent Laid-Open No. 131873/1983. As can be seen from FIG. 3, the steering force Fo of the conventional power steering device is constant regardless of vehicle speed.

[0018] Furthermore, even when the speed of the vehicle is increased,
The operation of the control valve 8 and the operation of the power cylinder device 2 when the steering wheel is turned to the right or left are similar to those disclosed in the above-mentioned Japanese Patent Laid-Open No. 131873/1983.

FIG. 2 shows a second embodiment of the invention. In the figure, the same reference numerals as those used in FIG. 1 indicate the same components as in the first embodiment. In this embodiment as well, the control valve 8 is built into the power piston 3, but in FIG. 2, it is shown separated from the power piston 3 as a sectional view taken along the line BB. The feature of this embodiment is that an oil discharge port 44B is added to the hydraulic reaction force chamber 44, and this oil discharge port 44B is connected to the oil reservoir 33 by a hydraulic oil discharge path 50. The point is that a variable orifice 51 is interposed between the two. The variable orifice 51 is operated by an actuator 52, and is controlled in accordance with instructions from the computer 37 so that its opening becomes smaller as the vehicle speed increases. By controlling the opening degree of the variable orifice 51 in this manner, in this second embodiment, the steering force Fo can be increased not only at the beginning of turning the steering wheel, but also gradually as the steering angle Θ increases. .

FIG. 5 shows the steering force F in the second embodiment.
The relationship between o and steering angle Θ is shown.

The rest of the structure of the second embodiment is the same as that of the first embodiment, and the operation of the control valve 8 and the power cylinder device 2 when the steering wheel is turned to the right or left is as follows. The aforementioned Japanese Patent Application Publication No. 62-131873
It is the same as that disclosed in the No.

[0022]

As explained above, according to the vehicle power steering system of the present invention, as the vehicle speed increases, the hydraulic pressure in the hydraulic reaction force chamber increases, and as the hydraulic pressure increases, the steering force increases. increases. Therefore, the straight-line stability of the vehicle is improved, and the driver can feel the steering wheel's speed sensitivity in the straight-line range.

[0023] Furthermore, if an oil discharge port is further formed in the hydraulic reaction chamber and the flow rate of the hydraulic oil flowing out from this oil discharge port is controlled to decrease as the vehicle speed increases, it is possible to maintain the steering at the beginning of turning the steering wheel. Not only can the force be increased, but the steering force can be gradually increased as the steering angle increases.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a power steering device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a power steering device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between steering force and steering angle of a conventional power steering device.

FIG. 4 is a diagram showing the relationship between steering force and steering angle of the power steering device according to the first embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between steering force and steering angle of a power steering device according to a second embodiment of the present invention.

[Explanation of symbols]

1 Power steering device 2 Power cylinder device 3 Power piston 4 Sector shaft 7 Worm shaft 8 Control valve 9 Spool 9A Spool shaft 34 Variable orifice 35 Oil pump 36 Actuator 37 Computer 38 Vehicle speed sensor 44 Hydraulic reaction chamber 45 Spring receiver 46 Spring receiver 47 Compression coil spring 51 Variable orifice 52 Actuator

Claims (1)

[Claims] 1. A control valve interlocked with the steering wheel of the vehicle is provided between a power cylinder device that applies steering force to the steering wheel of the vehicle and a hydraulic oil supply source that supplies hydraulic oil to the power cylinder device. In a power steering system for a vehicle, the control valve is installed to control the supply amount and supply direction of the hydraulic oil to the power cylinder system, the hydraulic reaction chamber for holding the control valve at a neutral position by hydraulic pressure. At the same time, a hydraulic pressure generating device is provided that generates hydraulic pressure corresponding to the vehicle speed of the vehicle, and the hydraulic pressure generated by the hydraulic pressure generating device is introduced into the hydraulic reaction chamber to move the power cylinder device to the neutral position. A power steering device for a vehicle, characterized in that the power steering device is held in place.