JPS643738Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a power steering system in a vehicle, etc., and its purpose is to connect both chambers of the power cylinder when the steering wheel is in a locked state, so that the hydraulic pump can reach the relief pressure. The purpose is to prevent unnecessary loads from being applied to the gear body and other parts.

In general, in automobiles equipped with a power steering system, even when the steering wheel is fully turned to the left or right and locked, the steering operating force is reduced, and during this time the hydraulic Since the pump operates and continues to supply pressure oil to one chamber of the power cylinder, unnecessary mechanical and hydraulic loads are borne on the gear body, vehicle side stopper and link, or piping system. This will promote deterioration of the main body. In addition, when the hydraulic pump is maintained at the relief pressure state as described above, the oil temperature rises abnormally, promoting deterioration of the oil and the seal ring inside the pump, which impairs the performance of the power steering system. This causes the problem of deterioration.

The present invention aims to improve such problems,
The embodiment will be specifically described below with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a power cylinder of a power steering device, and a valve housing 11 is fixed to one end of the power cylinder, and a servo device 12 that controls the supply and discharge of pressure oil to and from the power cylinder 10 is housed in this valve housing 11. has been done. The power cylinder 10 has a piston 1
3 is slidably assembled, and the power cylinder 10 is moved between the left chamber 10a and the right chamber 1 by means of this piston 13.
It is divided into 0b. A rack 14 is formed on the outer periphery of the piston 13, and a sector gear 16 formed on a cross shaft 15 is meshed with this rack 14. The crossshaft 15 is connected to the steering wheels via the required steering linkage. The servo valve device 12 includes a main valve member 17 fitted in the valve housing 11, and the main valve member 1.
It consists of a first spool valve 18 and a second spool valve 19 formed on both sides of the valve 7 and slidably housed in the valve chamber. Further, these spool valves 18 and 19 are connected to the steering shaft 20 via stug pins 38 and 39 that are press-fitted into the steering shaft 20.
is connected to. Since this steering shaft 20 is connected to a handle, rotation of the handle operates the spool valves 18 and 19, and the power cylinder 10
Controls the supply and discharge of pressure oil to perform power steering operations.
A threaded shaft 21 is integrally engaged with one end of the main valve member 17, and this threaded shaft 21 is inserted into the power cylinder 10 and is screwed into the piston 13 via a ball 22. Above screw shaft 2
1 is flexibly connected to the steering shaft 20 via a torsion bar 23. In addition, 25 and 26 in the figure
2 indicates a pressure oil supply port and a pressure oil discharge port provided in the valve housing 11, and 27 and 28 indicate pressure oil passages formed in the power cylinder 10 and the valve housing 11, respectively. The passage 27 is opened to the left chamber 10a of the power cylinder 10, and the passage 28 is opened to the right chamber 10b of the power cylinder 10, and is supplied from the supply port 25 by operating the servo valve device 12 by operating the handle. Pressure oil is distributed to one of the passages 27 and 28, and the other is communicated with the discharge port 26.

On the other hand, the power cylinder 10 has the passage 2
A bypass passage 30 is formed that branches from the piston 7, and this bypass passage 30 opens on the inner circumferential surface of the power cylinder 10 into which the piston 13 is fitted, and is normally closed by the body of the piston 13. In addition, the right chamber 1 of the power cylinder 10 is provided in the body of the piston 13.
A pair of V grooves (circumferential grooves) 31a, 31 communicating with 0b
b are located on both sides of the bypass passage 30.

In such a power steering device, when the handle is turned to the right, pressure oil from a hydraulic pump (not shown) is supplied to the left chamber 10a of the power cylinder 10 by the action of the servo valve device 12. This causes the piston 13 to move to the right. Then, the piston 13 reaches its final position, and the V groove 31a opens into the bypass passage 3.
0 and communicates with each other, pressure oil flows into the V groove 31a.
It is supplied to the right chamber 10b of the power cylinder 10 through. As a result, power steering action no longer takes place. On the other hand, when the handle is turned to the left, pressure oil is supplied to the right chamber 10b of the power cylinder 10, thereby causing the piston 13 to move to the left. Subsequently, when the V groove 31b intersects and communicates with the bypass passage 30, pressure oil passes from the V groove 31b of the piston 13 through the bypass passage 30 to the power cylinder 10.
are supplied to the left ventricle 10a, each left ventricle 10a, right ventricle 1
0b communicate with each other. Therefore, the power steering action is no longer performed, and it is possible to prevent the hydraulic pump from reaching relief pressure near the locked state of the steering wheel.
In this way, fatigue of the gear body, vehicle side stopper, etc. can be prevented, and oil deterioration can be prevented.

FIG. 2 shows another embodiment of the present invention. This is the same power cylinder 10 as above,
A hole 33 communicating with the passage 27 is provided, and this hole 3
Plunger 3 plunges into power cylinder 10 at 3
4 is slidably inserted into the piston 13, and annular cam grooves 35a and 35b are formed on the outer periphery of the piston 13 to make sliding contact with the end of the plunger 34. 37 is a bypass path provided in the plunger 34 in a T-shape.

In such a power steering device, when the steering wheel is turned to the right, pressure oil flows into the left chamber 10 of the power cylinder 10.
a, thereby causing the piston 13 to move to the right. Here, the plunger 34 receives the elastic force of the spring 36 and its tip contacts the outer peripheral surface of the piston 13, so the cam groove 34
When the plunger 5a reaches the plunger 34, its tip sinks into the cam groove 35a, so the bypass passage 37 communicates with the passage 27 and the right chamber 10b, and pressure oil flows into the right chamber 10b. , the right chamber 10b and the left chamber 10a communicate with each other, so that power steering action no longer takes place and the hydraulic pump is prevented from reaching relief pressure.

As explained above, by communicating the left and right chambers of the power cylinder with each other via the bypass path near the lock position of the handle, it is possible to generate relief pressure in the hydraulic pump at the lock position of the handle. This eliminates unnecessary loads on the gear body, piping system, stoppers and links on the vehicle side, suppresses fatigue, extends the life of the entire device, and stabilizes operation. Since there is no relief pressure generated as in the past, there are various practical advantages such as preventing abnormal increases in oil temperature and effectively suppressing oil deterioration and seal member damage and deterioration. Of course, since these various effects can be obtained with a simple structure, it is possible to provide a relatively inexpensive device without increasing the size of the device. In addition, since it has a simple structure and a relatively small number of parts, it has the advantage that the failure probability of the device is low.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the power steering device of the present invention, and FIG. 2 is a sectional view showing another embodiment. 10...Power cylinder, 10a...Left ventricle, 1
0b... Right ventricle, 12... Servo valve device, 13...
Piston, 30, 37... Bypass path, 31a,
31b, 35a, 35b...grooves (circumferential grooves).

Claims (1)

[Claims for Utility Model Registration] (1) A servo valve device is actuated based on the handle operation to control the switching of pressure oil, and by this pressure oil,
In a power steering device that obtains steering assist force by slidingly controlling the piston that divides the inside of the power cylinder into left and right chambers, the passageway that leads hydraulic pressure to the oil chamber of either the left or right chamber of the power cylinder. A bypass path branching from the power cylinder is opened in the power cylinder, and its open end is closed by the body of the piston at a substantially neutral position. A pair of circumferential grooves communicating with the other oil chamber are disposed facing each other on both sides of the bypass passage, and when the piston moves and the circumferential groove opens into the bypass passage, the circumferential grooves communicate with the other oil chamber. A power steering device characterized in that a left chamber and a right chamber of a power cylinder are communicated with each other. (2) The power steering device according to claim 1, wherein the bypass passage is provided in a plunger slidably inserted into a hole that crosses the passage.