JP2001317671A - Pipe joint and power steering system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint that is small in the number of parts items in use and is thus simple in structure, easy to assemble and inexpensive to manufacture, and a power steering system using the pipe joint. SOLUTION: A ball 9 is inserted in the vicinity of a connection end 41 of a metal pipe 4 so as to float along the line. The internal surface of the metal pipe 4 near the connection end 41 forms an annular valve seat 43, so that the ball 9 is brought into close contact with the valve seat 43 as moved in one direction. Near the connection end 41 of the metal pipe 4, a communicating passage 45 is formed to cause the connection end 41 side and the valve seat 42 side of the metal pipe 4 to communicate with each other when the ball 9 is separated from the valve seat 43. The connection end 41 of the metal pipe 4 is bent inward to prevent dislodgment of the ball 9 from the metal pipe 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe joint incorporating a check valve and a power steering apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a power steering device for assisting a steering force by hydraulic pressure has been frequently used as a steering device for a vehicle. This power steering device outputs a steering assist force by supplying hydraulic oil discharged from a hydraulic pump to a hydraulic actuator such as a hydraulic cylinder or a hydraulic motor. A hydraulic control valve that controls the supply of pressure oil to the hydraulic actuator in accordance with the steering direction and the steering resistance is interposed therebetween.

[0003] In this type of power steering device, the impact applied to the wheels when traveling on a rough road or when riding on a curb,
A so-called kickback phenomenon occurs in which the pressure oil supplied to the hydraulic actuator flows backward to the hydraulic pump side and the handle is taken off. Therefore, it is possible to prevent the kickback phenomenon from occurring by interposing a check valve for preventing the backflow of pressurized oil to the hydraulic pump in an oil passage connecting the hydraulic control valve and the hydraulic pump. (See, for example, Japanese Patent Application Laid-Open No. 10-273601).

FIG. 6 is a sectional view showing a pipe joint K constituting the check valve. This pipe fitting K is incorporated in the input port 102 of the hydraulic control valve 101, and is disposed at the inner back portion of the input port 102, and a valve seat 103a is formed at an inner circumference at an inner end side. A union seat 103, a cap 104 continuously arranged in the inner part of the union sheet 103, a ball 105 movably inserted into the union sheet 103 and the cap 104, and the input port 102. By screwing, the tube 106 connected to the hydraulic pump is
A sleeve nut 107 sandwiched between the union seat 103 and the union seat 103.
The check valve 100 is constituted by the three, the cap 104 and the ball 105. In addition, the cap 104 includes the inside of the hydraulic control valve 101 and the check valve 100.
A notch 104a for communicating with the inside of the device is formed. According to the pipe joint K constituting the check valve 100, when the internal pressure of the hydraulic control valve 101 increases, the ball 105 moves to the valve seat 103 of the union seat 103.
a, the backflow of the pressure oil to the hydraulic pump side can be prevented.

[0005]

The above conventional pipe joint K
The check valve 100 is a union seat 103, a cap 1
04 and the ball 105, when assembling them into the input port 102, first press the cap 104 into the inner part of the input port 102, and insert the ball into the cap 104. After inserting 105, the union sheet 103 is connected to the input port 102.
Need to be press-fitted. For this reason, there is a problem that it takes time to assemble the pipe joint K. In addition, the number of parts is large, and the union sheet 103 and the cap 104 need to be processed with high precision in order to secure the sealing property of the input port 102, so that the manufacturing cost is high. The present invention has been made in view of the above problems, and an object of the present invention is to provide a pipe joint which has a simple structure, is easy to assemble, and can reduce the manufacturing cost, and a power steering device using the same. And

[0006]

In order to achieve the above object, a pipe joint according to the present invention is characterized in that a bead is formed by radially swelling the vicinity of a connection end of a pipe, and a connection end side of the pipe is formed. While being introduced into the connection hole, the bead is sandwiched between a sleeve nut screwed into the connection hole and a step provided inside the connection hole, and an annular ring provided on the inner side of the bead. In a pipe joint for sealing a gap between the connection hole and the pipe by means of a seal, a connection between the ball freely inserted along the pipe line inside the vicinity of the connection end of the pipe and the pipe, An annular valve seat, which is formed by an inner peripheral surface near the end and is closely attached to the ball as the ball moves in one direction, and is provided near a connection end of the tube, and the ball separates from the valve seat. In this state, communication is established between the connection end side of the pipe and the valve seat side. A check valve comprising a communication passage to be formed, and a locking portion formed by inwardly projecting the connection end of the tube body or the vicinity thereof and preventing the ball from being pulled out from the connection end. It is a feature (claim 1).

A power steering apparatus according to the present invention is provided with a hydraulic pump, a hydraulic actuator for outputting a steering assist force by pressure oil supplied from the hydraulic pump, and a hydraulic actuator interposed between the hydraulic pump and the hydraulic actuator. In a power steering apparatus comprising a hydraulic control valve for controlling supply and discharge of hydraulic oil to and from the hydraulic actuator in accordance with steering, a predetermined portion of a hydraulic circuit between an output port of the hydraulic pump and an input port of the hydraulic control valve In addition, the pipe joint according to claim 1 is provided (claim 2).

According to this structure, since the check valve is composed of the pipe and the ball, the number of parts of the pipe joint can be reduced and the gap between the connection hole and the pipe is formed by the annular seal. Since the sealing is performed, the gap can be sealed without performing high-precision processing on the pipe joint. Also,
It is possible to assemble the pipe joint into the connection hole simply by inserting the connection end portion of the pipe into the connection hole and sandwiching the bead between the sleeve nut and the step provided inside the connection hole. it can.

In the power steering device, it is preferable that a pipe joint is provided at an input port of a hydraulic control valve (claim 3). In this case, the connection hole is formed by an input port of the hydraulic control valve. Therefore, the number of parts of the pipe joint can be further reduced.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic view showing one embodiment of a power steering apparatus according to the present invention. The power steering device A includes an input shaft S connected to a steering handle (not shown), a pinion 1 that rotates with the rotation of the input shaft S, a rack shaft 2 that meshes with the pinion 1, and a rack shaft 2 that A hydraulic cylinder 6 serving as a hydraulic actuator provided inside the housing 5, a hydraulic pump 7 for supplying hydraulic oil to the hydraulic cylinder 6, and a hydraulic cylinder 6 The main part is constituted by a hydraulic control valve 8 for controlling the supply and discharge of the pressure oil.

Both ends of the rack shaft 2 are connected to a housing 5
The ball joints 10 and 11 are integrated with the protruding ends of the both ends 5a and 5b. Each ball joint 10 and 11 has a tie rod 1
2, 13 are attached, and this tie rod 12,
Both ends of the rack shaft 2 are connected to the steered wheels via 13. Therefore, the steering operation of the vehicle can be performed by rotating the pinion 1 via the input shaft S and moving the rack shaft 2 in the axial direction (vehicle width direction) by rotating the steering handle.

The hydraulic cylinder 6 includes a cylinder tube 6a formed by the housing 5, a piston rod 6b formed by the rack shaft 2, and a piston 6c integrated with the rack shaft 2. The sandwiched two-sided space is configured as a first oil chamber 6d and a second oil chamber 6e.

The hydraulic control valve 8 is constituted by a rotary valve, and its valve housing 8a has an input port 8b, a return port 8c, and a first port.
The output port 8d and the second output port 8e are formed to protrude, respectively. The input port 8b is connected to an output port 7a of the hydraulic pump 7 via a first hydraulic pipe P1, and the return port 8c is connected to a second hydraulic pipe P2.
Is connected to the reserve tank T via The first output port 8d is connected to a first oil chamber 6d of the hydraulic cylinder 6 via a third hydraulic pipe P3, and the second output port 8e is connected to a hydraulic cylinder 6 via a fourth hydraulic pipe P4.
Is connected to the second oil chamber 6e. The hydraulic control valve 8 controls each oil chamber 6 according to the steering direction and the steering resistance.
The hydraulic oil for assisting the steering force is supplied to one of d and 6e, and at the same time, the hydraulic oil is returned to the reserve tank T from the other oil chamber.

The first hydraulic pipe P1 has a flexible pipe 3 having a downstream end connected to the input port 8b of the hydraulic control valve 8, and an output port 7 of the hydraulic pump 7 having an upstream end.
The flexible pipe 3 and the metal pipe 4 are connected to each other via a pipe joint 20. Referring to FIG. 2, the pipe joint 20 has a connection hole H of a joint housing 21.
The connection end 41 side of the metal tube 4 is introduced into the metal tube 4.
The bead 42 formed in the metal pipe 4 is fastened by a sleeve nut 25 loosely fitted near the connection end 41 of the metal pipe 4. A hydraulic control valve is provided inside the metal pipe 4 near the connection end 41. Hydraulic pump 7 from 8 side
A check valve C for preventing backflow of pressurized oil is provided.

The joint housing 21 is formed by integrally forming a cylindrical portion 21b for fixing an end portion of the flexible tube 3 at one end of a hexagonal cylindrical main body portion 21a. With the inner periphery inserted into the outer periphery of the cylindrical portion 21b, the tube is prevented from being pulled out by the caulking tube. The connection hole H is provided in the cylindrical portion 21.
The connection hole H is formed inside the main body 21a in a state of communication with the inside of the connection hole H. A female screw 21c for screwing the sleeve nut 25 is formed on the introduction port side of the connection hole H. In the inner part, the female screw 21c
A step portion 21d smaller than the inner diameter of is formed. The bead 42 formed near the connection end 41 of the metal tube 4 is formed by expanding the vicinity of the connection end 41 of the metal tube 4 over the entire circumference in the radial direction. The bead 42 is clamped between the stepped portion 21 d of the connection hole H and the tip of the sleeve nut 25. Further, an O-ring 22 as an annular seal is wound around a position adjacent to the bead 42.
A connection end 4 between the connection hole H and the metal tube 4 is formed by a ring 22.
The gap with the vicinity of 1 is sealed.

Between the connection end 41 of the metal tube 4 and the bead 42, the connection end 41 side is a tapered tube 4a whose diameter gradually increases, and an inner peripheral surface at an intermediate portion in the axial direction serves as a valve seat 43. It is configured. A ball 9 is movably inserted into the tapered pipe 4a along the pipe. When the ball 9 is moved to the bead 42 side, the outer peripheral surface of the ball 9 is in close contact with the valve seat 43 of the tapered pipe 4a over the entire circumference. The connection end 41 of the metal tube 4
Is formed with a locking portion 44 for restricting the ball 9 from jumping out of the connection end 41 by bending the ball inward.
A communication path 45 is formed before the valve seat 3 to allow the connection end 41 of the metal tube 4 to communicate with the valve seat 43 in a state where the ball 9 is separated from the valve seat 43. The communication passage 45 is formed by cutting two opposing locations on the outer periphery of the tapered tube 4a from the connection end 41 side toward the valve seat 43 in the case of the drawing (see FIG. 3). As described above, the check valve C including the valve seat 43, the ball 9, the communication passage 45, and the like can be configured.

The check valve C moves the ball 9 to the valve seat 43.
In a state where the ball 9 is separated from the hydraulic pump 7 and the ball 9 is in close contact with the valve seat 43, the pressure is supplied from the hydraulic control valve 8 to the hydraulic pump 7 side. Oil can be prevented from flowing back. Therefore, the pressure oil supplied from the hydraulic control valve 8 to the hydraulic cylinder 6 tends to flow back to the hydraulic pump 7 via the hydraulic control valve 8 due to an impact applied to the wheel when traveling on a rough road or riding on a curb. Then, the ball 9 of the check valve C is brought into close contact with the valve seat 43 due to the increase in the pressure, and the backflow of the pressure oil can be prevented.

In the pipe joint 20 having the above-described structure, the check valve C is constituted by the metal pipe 4 and the ball 9, so that the number of parts is small and the structure can be simplified accordingly. In addition, since the gap between the connection hole H and the metal pipe 4 is sealed by the O-ring 22,
Of the connection hole H can be ensured without processing with high precision. Therefore, the manufacture of the pipe joint 20 is easy, and the manufacturing cost can be reduced. Moreover,
The connection end 41 of the metal tube 4 is inserted into the connection hole H, and the sleeve nut 25 loosely fitted into the metal tube 4 is screwed into the female screw 21c of the connection hole H, so that a step 21d inside the connection hole H is formed. The pipe joint 20 can be assembled to the connection hole H only by sandwiching the bead 42 of the metal pipe 4 between the metal pipe 4 and the metal pipe 4, so that the assembly can be performed easily and efficiently.

In the above embodiment, the valve seat 43 is formed by the tapered tube 4a of the metal tube 4.
However, the present invention is not limited to this. For example, as shown in FIG. 4, a circumferential groove 46 for introducing the O-ring 22 is formed by reducing the inner and outer circumferences of a portion of the metal tube 4 adjacent to the bead 42. The valve seat 43 may be formed on the inner peripheral portion of the portion where the peripheral groove 46 is formed. As shown in FIG. 5, the locking portion 44 for preventing the ball 9 from being pulled out is connected to the metal tube 4.
May be formed by inwardly depressing the vicinity of the connection end 41 at regular intervals along the peripheral surface.

In the above embodiment, the pipe joint 20 is provided in the middle of the first hydraulic pipe P1 connecting the input port 8b of the hydraulic control valve 8 and the output port Pa of the hydraulic pump P. This may be provided at the input port 8 b of the hydraulic control valve 8. In this case, the input port 8
b, the connection hole H can be formed.
The number of parts can be further reduced, and the manufacturing cost can be further reduced.

[0021]

As described above, according to the present invention, since the check valve of the pipe joint is constituted by the pipe and the ball,
The number of parts is small, and the structure can be simplified accordingly. In addition, the gap between the connection hole and the pipe body is sealed by an O-ring, and the connection hole can be securely sealed without processing the pipe joint with high precision. Thus, the manufacturing cost can be reduced. Moreover, the pipe joint can be assembled to the connection hole only by sandwiching the bead of the tube between the sleeve nut loosely fitted in the pipe and the step provided in the connection hole. Assembly can be performed easily and efficiently.

In particular, for a power steering device in which the pipe joint is provided at the input port of the hydraulic control valve, the connection hole can be formed by the input port of the hydraulic control valve, so that the number of parts of the pipe joint is further reduced. And the manufacturing cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a power steering device of the present invention.

FIG. 2 is an enlarged sectional view showing a pipe joint.

FIG. 3 is a perspective view showing the vicinity of a connection end of a metal tube.

FIG. 4 is a sectional view of a main part showing another embodiment of the pipe joint.

FIG. 5 is a cross-sectional view of a main part showing still another embodiment of the pipe joint.

FIG. 6 is a sectional view showing a conventional pipe joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pinion 2 Rack shaft 3 Flexible pipe 4 Metal pipe (tube body) 41 Connection end 42 Bead 43 Valve seat 44 Locking part 45 Communication passage 5 Housing 6 Hydraulic cylinder (hydraulic actuator) 7 Hydraulic pump 8 Hydraulic control valve 20 Pipe joint 21 Joint housing 21d Step 22 O-ring (annular seal) 25 Sleeve nut 9 Ball A Power steering device C Check valve S Input shaft P1 First hydraulic piping H Connection hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D033 ED03 3H016 AD04 3H017 AA00 3H025 BA22 BB04 3H058 AA04 BB22 BB29 CA20 CB02 CB03 CB04 CB14 CC07 CC15 EE03 EE18

Claims (3)

[Claims] 1. A sleeve nut screwed into said connection hole in a state in which a bead is formed by swelling in the vicinity of a connection end of a tube in a radial direction and a connection end side of said tube is introduced into a connection hole. A pipe that sandwiches the bead between a step provided inside the connection hole and seals a gap between the connection hole and the pipe by an annular seal provided inside the bead. In the joint, the ball is constituted by a ball freely inserted along the pipeline inside the vicinity of the connection end of the tube, and an inner peripheral surface near the connection end of the tube, and the ball moves in one direction. An annular valve seat to which the ball is closely attached, and provided near the connection end of the pipe body, between the connection end side of the pipe body and the valve seat side while the ball is separated from the valve seat. A communication path for communicating the Formed Te, pipe fitting said ball, characterized in that it comprises a check valve comprising a locking portion which prevent the dropping off from the connection end. 2. A hydraulic pump, a hydraulic actuator for outputting a steering assist force by hydraulic oil supplied from the hydraulic pump, and a hydraulic actuator interposed between the hydraulic pump and the hydraulic actuator, the hydraulic pump being adapted to act on the hydraulic actuator in accordance with steering. 2. A power steering apparatus comprising a hydraulic control valve for controlling supply and discharge of pressurized oil, wherein the pipe according to claim 1 is provided in a predetermined portion of a hydraulic circuit between an output port of the hydraulic pump and an input port of the hydraulic control valve. A power steering device comprising a joint. 3. The power steering apparatus according to claim 2, wherein said pipe joint is provided at an input port of a hydraulic control valve.