JPH0131586Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a power steering device for a vehicle that applies a hydraulic steering reaction force in accordance with vehicle speed.

In order to reduce the steering force of the vehicle,
In the case of a power steering device that uses hydraulic pressure to power assist during steering, hydraulic reaction force is fed back to the input shaft in order to prevent the steering wheel from becoming too light due to the power assist and to give the driver an appropriate operating feel. are doing.

By the way, in order to maintain steering stability during high-speed driving, when a high vehicle speed is detected separately from the hydraulic steering reaction force, for example, the flow rate of pressure oil sent to the power cylinder is reduced to reduce the power assist force. There is something I did.

The steering sensation provided by the hydraulic reaction force is primarily to prevent the steering wheel from being turned too far, and therefore the reaction force increases in proportion to the rotational speed of the steering wheel. This does not mean that a large reaction force can be obtained in the range, and the steering reaction force is applied regardless of the vehicle speed.

Therefore, in order to obtain stability at high speeds, it is necessary to separately provide the above-mentioned flow rate control means, and in this case, the structure becomes unavoidably complicated.

On the other hand, British Patent No. 810716 discloses a device that increases the steering reaction force according to the vehicle speed. High-speed stability is ensured by changing the steering reaction force at low and medium speeds and the steering reaction force at high vehicle speeds without providing a separate vehicle.

However, in order to apply the valve switching reaction force as a steering reaction force, this device requires a hydraulic source whose hydraulic pressure is controlled according to the vehicle speed, and a plurality of auxiliary pistons that operate in response to this hydraulic pressure. The drawback was that it was mechanically quite complex.

The present invention was proposed in order to solve this problem, and includes a hydraulic switching valve that switches in response to a signal from the vehicle speed detection means, and connects the spool and sleeve of the control valve via the hydraulic switching valve. A power steering system that has a simplified structure by applying pressure oil from the pump port generated during steering operation to a reaction force chamber formed in the cylinder, increasing the valve reaction force only during high-speed steering operations. The purpose is to provide

In order to achieve these objectives, the present invention is equipped with a rotary control valve that switches based on input rotation from the steering wheel, and selectively supplies pressurized oil to the output drive unit connected to the wheels via the control valve. In the power steering device, a long groove is formed in the circumferential direction spanning the spool and sleeve of the control valve, and a reaction force tip positioned astride the spool and sleeve is slid at both ends of the long groove. A reaction force chamber is formed by freely moving the chips, and a reaction spring is interposed between both reaction force chips.A vehicle speed detection means for detecting the high speed range of the vehicle is provided, and a signal from this detection means is provided. It is equipped with a hydraulic switching valve that switches in the high-speed range and directs pressure oil from the pump port to the reaction chamber.

Hereinafter, embodiments of the present invention will be described based on the drawings.

In FIG. 1, the main body of the apparatus is composed of a power cylinder section (output drive section) 1 and a control valve 2.
First, in the power cylinder section 1, a stub shaft 3 connected to a handle (not shown) is rotatably attached to a housing 4, and an inner shaft 5 fixed to the stub shaft 3 has a torsion bar 6.
A screw shaft 7 fixed to the other end is suspended horizontally within the housing 4.
A piston 8 slidably housed in the housing 4 is screwed into a feed screw portion (not shown) formed in the housing 4 via a ball (not shown), and a rack 9 formed on the piston 8 is engaged with a sector gear 10. is connected to the steering link of the wheel.

Next, the control valve 2 is connected to the valve housing 11
The sleeve 12 is rotatably inserted into the inner hole of the sleeve 12, and the spool 13 is rotatably inserted into the inner hole of the sleeve 12, and one end of the sleeve 12 is fixed to one end of the screw shaft 7.
4 receives and engages one end of a pin 15 passing through the inner shaft 5 and torsion bar 6.

As shown in FIG. 2, this control valve 2 is formed with two long grooves 16 extending in the circumferential direction across both the sleeve 12 and the spool 13.

Two reaction tips 17 that engage with the sleeve 12 and the spool 13 are inserted oppositely into both ends of the long groove 16 in the circumferential direction, and a reaction spring 18 is interposed between them. A reaction force chamber 19 is defined by the reaction force chip 16 and the reaction force chip 17, respectively.

On the other hand, on the inner surface of the valve housing 11, a pump port 20, two operating ports (not shown), and two tank ports are also provided on the sleeve 1.
Two communication grooves (not shown) are formed on the outer circumferential surface of the device 2, but their structure and operation belong to well-known technology and will not be described in detail here.

Inside the valve housing 11, there is a reaction passage 21 that communicates the pump port 2 and the reaction chamber 19.
A hydraulic switching valve 2 is installed in the passage 21.
2 are interposed. This hydraulic pressure switching valve 22 is opened by being driven by a solenoid (not shown) to guide the hydraulic pressure of the pump port 20 to the reaction force chamber 19.This solenoid is connected to a vehicle speed detection means 23 for detecting a high vehicle speed range. The signal is powered up and supplied via the amplification circuit 24.

Next, the effect will be explained.

Now, when the handle is turned in the direction of arrow R, for example, to rotate the screw shaft 7 via the stub shaft 3, inner shaft 5, and torsion bar 6 connected thereto, the sector gear 10 is rotated.
Since the piston 8 meshing with the piston 8 is in a pseudo-fixed state based on the ground resistance, the torsion bar 6 is twisted.

Therefore, the spool 13 engaged with the torsion bar 6 via the pin 15 is also displaced in the R direction by the same amount as the torsion bar 6 while compressing the reaction spring 18 as shown in the third diagram, and the reaction force chamber 19 At the same time, the control valve 2 is switched from the neutral position shown in FIG. 2 to the R direction.

Then, the pressure oil in the pump port 20 is sent to the power cylinder section 1, presses the piston 8, rotates the sector gear 10 that meshes with the rack 9, and rotates the wheel.
change direction. As long as there is a handle input from now on,
The screw shaft 7 also rotates while maintaining the same phase as the inner shaft 5, and the sleeve 12 of the control valve 2 rotates in the same direction and with the same phase as the spool 13, so that the wheels are continuously turned.

By the way, at this time, the spool 1 of the control valve 2
3, the torsion bar 6 and the reaction spring 18 act as resistance, which causes a steering reaction force to act on the steering wheel. However, when the vehicle speed is low and the solenoid of the hydraulic switching valve 22 is not energized, the hydraulic switching valve 22 acts as a resistance. The valve 22 is closed, and no acting force is generated except for the torsion bar 6 and the reaction spring 18. In other words, the steering reaction force in the low to medium speed range can be kept small.

On the other hand, when the solenoid is energized based on the signal from the vehicle speed detection means 23 in a high speed range, the hydraulic pressure switching valve 22 opens and the pressure oil of the pump port 20 is transferred to the reaction chamber 21 via the reaction passage 21. is guided.

Therefore, the pressure in the reaction force chamber 19 increases, and the reaction tip 17 works to return the spool 13, which is about to switch in the R direction, to the neutral direction, so that the steering reaction force on the handlebar side increases by that amount. .

In this way, a relatively large steering reaction force is generated in a high vehicle speed range compared to a low vehicle speed, thereby improving the stability of high-speed steering.

Note that when the spool 13 of the control valve 2 is displaced in the L direction contrary to the above, the L direction of the spool 13 is
This increases the resistance to displacement in the direction and generates a predetermined hydraulic steering reaction force.

As explained above, according to the present invention, when steering at high speeds, hydraulic pressure is applied to counteract the displacement of the control valve spool to increase the steering reaction force, thereby stabilizing the steering at high speeds. In addition, since the hydraulic pressure from the pump port of the control valve is used as the hydraulic pressure for generating reaction force, the structure is simple as no hydraulic power source is required, and the hydraulic pressure for reaction force is not generated except during steering. This has the advantage that there is no need to worry about malfunctions. In addition, according to the present invention, a reaction force chamber is defined in the circumferential direction between the sleeve and the spool, and the reaction force chips are arranged on the circumference, so that a compact structure can be achieved in the radial direction. Further, since the reaction force chamber having a rectangular cross section is defined within the long groove, there is an advantage that the pressure receiving area of the reaction force chip can be maximized within a limited space. In addition, in this invention, the control valve groove and the hydraulic reaction groove formed in the sleeve/spool are arranged on the same inner and outer diameters, making it easy to process them to ensure the required positional accuracy. Easy to measure. Furthermore, the present invention has the advantage that the reaction force spring is interposed between the reaction force chips, so that the initial reaction force at the neutral time can be arbitrarily set according to the load setting of the reaction force spring.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the present invention, and Fig. 2 is a main part of the control valve in the neutral position of Fig. 1.
FIG. 3 is a partially enlarged sectional view taken along the line A, and is a view similar to FIG. 2 of the control valve in the spool displacement position. 1...Power cylinder section, 2...Control valve,
6... Torsion bar, 7... Screw shaft, 11... Valve housing, 12... Sleeve, 13... Spool, 15... Pin, 17...
Reaction chip, 18...Reaction force spring, 19...Reaction force chamber, 20...Pump port, 21...Reaction force passage,
22...Hydraulic switching valve, 23...Vehicle speed detection means.

Claims (1)

[Scope of utility model registration request] In a power steering device that is equipped with a rotary type control valve that switches and operates based on input rotation from a steering wheel, the control valve selectively supplies pressurized oil to an output drive unit connected to wheels via the control valve. A long groove is formed in the circumferential direction spanning the spool and sleeve of the valve, and a reaction force chip located at both ends of the long groove is slidably housed to form a reaction chamber. A reaction force spring is interposed between both reaction force chips, and a vehicle speed detection means for detecting the high speed range of the vehicle is provided, and based on a signal from this detection means, switching is made in the high speed range to the reaction force chamber. A power steering device characterized by comprising a hydraulic switching valve that guides pressure oil from a pump port.