JPH0320639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for absorbing surge waves generated in a hydraulic piping system.

[Prior Art] When surge waves occur in high-pressure oil pipes connected to the discharge side of a hydraulic power source such as a hydraulic pump, they cause harmful vibrations and noise in the piping system. Devices that absorb such surge waves include, for example, rubber bag-type accumulators and gas-free piston-type accumulators in which high-pressure gas is sealed in a container, or spring-piston-type accumulators in which a piston is installed inside a cylinder. There are known devices that house a compression spring that biases the .

Surge waves generated in the hydraulic oil due to the pulsation of the hydraulic pump are transmitted to the oil chamber inside the accumulator as oil elastic compression waves (compression waves in which changes in volume are transmitted as changes in density). The varying volume of oil is absorbed by the internal gas or by the deflection of the spring.

[Problems to be Solved by the Invention] Conventional accumulators are installed in the middle of a high-pressure oil pipe connected to the discharge side of a hydraulic power source, but the oil chamber inside the accumulator cannot be used as the main flow pipe for hydraulic oil. These accumulators must be connected to the main pipe (high-pressure oil pipe) via branch pipes that branch off from the main pipe. In this case, since the container of the accumulator protrudes in a direction perpendicular to the main pipe, it may be difficult to secure a mounting space for the accumulator.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an axial flow type surge absorber that can be constructed compactly and requires a small installation space.

[Means for Solving the Problems] In order to achieve the above object, the axial flow type surge absorption device of the present invention is provided in the middle of an oil path connecting the discharge side of a hydraulic power source and equipment moved by hydraulic pressure. A main flow pipe for hydraulic oil having a different diameter portion where the outer diameter changes in a part in the pipe axis direction, and a main flow pipe provided so as to be slidable in the pipe axis direction on the outer peripheral surface side of the main flow pipe so as to surround the different diameter portion. a hollow cylindrical piston; an oil chamber located at a position surrounded by an inner surface of the piston and an outer peripheral surface of the main flow pipe and communicating with the inside of the main flow pipe via a flow means; and a side of the piston. The piston is inserted in a compressed state between a first spring seat provided on the main flow pipe side and a second spring seat provided on the main flow pipe side, thereby reducing the volume of the oil chamber. It is equipped with a spring that applies force.

[Operation] The pressure of the hydraulic oil flowing through the main flow pipe acts on the oil chamber between the main flow pipe and the piston, and the piston is pushed to a position where the repulsive force of the spring and the oil pressure are balanced.
When a surge wave occurs in this state, the piston moves in the axial direction of the main flow pipe according to the magnitude of the fluctuating oil pressure acting on the oil chamber, and the elastic compression wave is absorbed by the volume fluctuation of the oil chamber. , it is possible to prevent surge waves from propagating downstream.

[Example] A first example of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 shows a power steering device 1 used in a steering system of an automobile. This power steering device 1 includes a vane pump 3 as an example of a hydraulic power source that is rotationally driven by an engine 2. A flow control valve 4 provided on the discharge side of the vane pump 3 is connected to the engine 2.
The flow rate of hydraulic oil is controlled according to the rotation speed of the Further, a relief valve 5 is provided to limit the maximum oil pressure.

A reservoir tank 8 is connected to the suction side of the vane pump 3 via an oil feed pipe 7. Hydraulic oil 9 is accommodated inside the reservoir tank 8 .
The pressure inside the reservoir tank 8 is approximately atmospheric pressure.

Similar to the well-known manual steering system, a steering force transmission mechanism 12 of, for example, a rack and pinion type is provided at one end of the steering shaft 11. A steering wheel 13 is provided on the other end side of the steering shaft 11. A rack shaft 16 that passes through the power cylinder 15 in the axial direction moves in the left-right direction in the drawing in conjunction with the rotation of the steering shaft 11. This rack shaft 16 drives a steering linkage (not shown).

Inside the power cylinder 15 is the easy piston 1
7 partitions the first cylinder chamber 18 and the second cylinder chamber 19, and each cylinder chamber 18, 1
9 are connected to a high pressure oil pipe 25 and a return pipe 26 via oil passages 21, 22 and a control valve 23, respectively. The high pressure oil pipe 25 is connected to the discharge side of the flow control valve 4 via an axial flow type hydraulic surge absorber 30, which will be described later.

The control valve 23 forms a flow path for an operating shaft depending on the steering direction of the steering shaft 11. For example, when the steering wheel 13 is rotated so that the rack shaft 16 moves to the right side in the figure, the hydraulic oil sent from the high-pressure oil pipe 25 is sent into the first cylinder chamber 18 through one oil passage 21. Easy axis 16
An axial force is generated in the right direction as shown in the figure. On the contrary, easy axis 1
When the steering wheel 13 is rotated so that the shaft 6 moves to the left side in the figure, the hydraulic oil from the high pressure oil pipe 25 is sent into the second cylinder chamber 19 through the other oil passage 22, thereby moving the rack shaft 16 to the left side in the figure.
An axial force is generated in the left direction as shown in the figure.

An axial flow type surge absorber 3 is installed in the middle of the high pressure oil pipe 25.
0 is set. As shown in Figure 2,
The surge absorber 30 includes a main flow pipe 31 as a center stud connected to the high pressure oil pipe 25, a cylindrical piston 32, a spring 33, and the like. On the outer periphery of the main flow pipe 31, two parts having different outer diameters from each other in the pipe axis direction, namely a large diameter part 35 and a small diameter part 36, are formed. In this specification, the stepped portion between the large diameter portion 35 and the small diameter portion 36 is referred to as a different diameter portion 37. In addition, the main flow pipe 31
A first spring seat 40 is provided on one end side.
A stopper 41 is provided at the other end of the main flow pipe 31.

A cylindrical piston 32 is provided on the outer peripheral surface side of the main flow pipe 31 so as to surround the different diameter portion 37, and this piston 32
It is slidable in the axial direction of the tube. A sealing material 4 such as an O-ring is provided at both ends of the inner circumferential surface of the piston 32 to maintain liquid tightness with the outer circumferential surface of the main flow pipe 31.
2,43 are provided.

The annular oil chamber 45 is located at a position surrounded by the inner circumferential surface of the piston 32 and the outer circumferential surface of the main flow pipe 31 including the different diameter portion 37, and this oil chamber 45 is located through a hole 46 as an example of a circulation means. It communicates with the inside of the main flow pipe 31 . Further, a second spring seat 47 is provided on the outer circumference of the piston 32.

A compression coil spring 33 is provided between the first spring seat 40 and the second spring seat 47. This spring 33 urges the piston 32 in a direction that reduces the volume of the oil chamber 45 (leftward in FIG. 2). The spring 33 may be a coil spring of equal pitch, but it is preferable to use a coil spring of unequal pitch as illustrated in FIG. 3, so that as the load increases, the amount of contact between the wires increases, and the spring constant becomes non-linear. It may be increased.

Next, the in-line surge absorber 3 with the above configuration
The operation of the power steering device 1 equipped with 0 will be explained.

When the engine 2 rotates, hydraulic oil discharged by the rotation of the vane pump 3 passes from the flow control valve 4 through the main flow pipe 31 of the in-line surge absorber 30 and the high pressure oil pipe 25 to the control valve 2.
3 and returns to the reservoir tank 8 via the return pipe 26. While the engine 2 is rotating, a reference oil pressure of a certain level or higher (for example, any pressure value in a pressure range of about 50 to 120 Kgf/cm ² ) acts on the high pressure oil pipe 25 . Axial flow type surge absorption device 30
In this case, a part of the hydraulic oil flowing through the main flow pipe 31 flows into the oil chamber 45 through the hole 46, so that the piston 32 is pushed to the right in the figure while bending the spring 33. The piston 32 stops at a reference position where the pressure of the hydraulic oil flowing in the main flow pipe 31 and the reaction force of the spring 33 are balanced. The area of the piston pressure receiving portion 48 is expressed by the difference between the outer diameter cross-sectional area of the large diameter portion 35 and the outer diameter cross-sectional area of the small diameter portion 36.

When the steering wheel 13 is rotated by the driver, hydraulic oil sent from the high-pressure oil pipe 25 flows into the first cylinder chamber 18 (or the second cylinder chamber 19) according to the steering direction of the steering shaft 11. By flowing in, the axial force of the rack shaft 16 is reduced to the right or left. The hydraulic oil pushed out from the second cylinder chamber 19 (or the first cylinder chamber 18) by the movement of the rack piston 17 is returned to the reservoir tank 8 via the control valve 23 and the return pipe 26.

When a surge wave is generated in the high-pressure oil pipe 25 or the like due to the operation of the vane pump 3, the surge component is synthesized with the reference pressure of the high-pressure hydraulic oil. Changes in the volume of the hydraulic oil due to surge waves act on the oil chamber 45 through the hole 46 of the surge absorber 30, so the piston 32
moves in the axial direction of the main flow pipe 31 from the reference position. By expanding or contracting the volume of the oil chamber 45 in this manner, surge waves are absorbed while maintaining the reference pressure of the hydraulic oil. Therefore, it is possible to prevent surge waves from propagating to the control valve 23 and power cylinder 15 side. The power steering device of this embodiment equipped with this axial flow type surge absorber 30 has a significantly lower pulsating pressure than a conventional product without a surge absorber, and this results in vibration and noise in the piping system. The occurrence of was also reduced.

The axial flow type surge absorber 30 allows the entire flow of the hydraulic oil flowing in the high pressure oil pipe 25 to flow through the main flow pipe 31 as a center stud, and the piston 32 reciprocates in the axial direction of the main flow pipe 31. Therefore, there is no need to connect a branch pipe in a direction perpendicular to the high pressure oil pipe 25, and the installation space can be small. Moreover, since the piston 32, the main flow pipe 31, and the annular oil chamber 45 are arranged concentrically inside the coil spring 33, the entire device can be constructed extremely compactly.

FIG. 4 shows a second embodiment of the present invention. In this embodiment, the large diameter portion 35 is formed by expanding the diameter of a part of the main flow pipe 31 by plastic working. A different diameter portion 37 whose outer diameter changes in a tapered manner is provided between the small diameter portion 36 and the smaller diameter portion 36, and a hole 46 as a flow means is provided in this different diameter portion 37. Therefore, the thickness of the wall of the main flow pipe 31 does not need to change substantially in the pipe axial direction.

The axial flow type surge absorber of the present invention can also be used by being directly connected to the outlet of a hydraulic pump, a safety valve such as the relief valve 5, or the control valve 23. The hydraulic power source may be other than a vane pump. Moreover, it goes without saying that it can be used in hydraulic equipment other than power steering devices.

[Effects of the Invention] The axial flow type surge absorber of the present invention can be configured extremely compactly compared to conventional accumulators, and requires less installation space.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic system diagram of a power steering device equipped with an axial flow type surge absorption device showing an embodiment of the present invention, and Fig. 2 is a sectional view of the axial flow type surge absorption device showing an embodiment of the present invention. 3 is a side view showing an example of an unequal pitch coil spring, and FIG. 4 is a sectional view of an axial flow type surge absorber showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Power steering device, 3... Vane pump (hydraulic source), 25... High pressure oil pipe, 30... Surge absorption device, 31... Main flow pipe, 32... Piston, 33
...Spring, 35...Large diameter part, 36...Small diameter part, 37...Different diameter part, 40...First spring seat, 45...Oil chamber, 46
...hole (flow means), 47...second spring seat.

Claims (1)

[Scope of Claims] 1. A portion of different diameter that is provided in the middle of an oil path connecting the discharge side of a hydraulic power source that generates hydraulic pressure and equipment that is moved by hydraulic pressure, and whose outer diameter changes in a part of the pipe axis direction. a cylindrical piston provided slidably in the tube axis direction on the outer circumferential surface side of the main flow pipe so as to surround the different diameter portion, and an inner surface of the piston and the main flow an oil chamber located at a position surrounded by the outer peripheral surface of the main flow pipe and communicating with the inside of the main flow pipe via a flow means; a first spring seat provided on the piston side and a first spring seat provided on the main flow pipe side; a spring that is interposed in a compressed state between a provided second spring seat and urges the piston in a direction to reduce the volume of the oil chamber;
An axial flow type hydraulic surge absorption device characterized by comprising: 2. The axial flow type according to claim 1, wherein the spring is a compression coil spring, and the main flow pipe is inserted through the center of the spring, and the main flow pipe, the piston, and the coil spring are provided concentrically. Hydraulic surge absorber. 3. The axial flow type hydraulic surge absorber according to claim 1, wherein the spring is an unequal pitch coil spring.