JPH0217294A - Axial flow type hydraulic surge absorbing device - Google Patents

Abstract

PURPOSE:To make a device compact in the device for absorbing surge waves generated in a hydraulic oil piping system by forming the device with the main flow passage pipe of a working fluid provided midway in an oil passage, a cylindrical piston, an oil chamber, and an energizing spring. CONSTITUTION:A device 30 has a main flow passage pipe 31 as a center stud connected to a high-pressure oil pipe, a cylindrical piston 32, and a spring 33, etc. to absorb surge waves generated in a hydraulic oil piping system. A deformed portion 37 formed with a large diameter portion 35 and a small diameter portion 36 having mutually different outside diameters in the pipe axial direction is provided on the outer peripheral portion of the main flow passage pipe 31. A piston 32 is slidably provided surrounding this deformed portion 37. An oil chamber 45 is provided between the inner face of the piston 32 and the outer face of the main flow passage pipe 31 while being connected to the inside of the main flow passage pipe 31, and the spring 33 energizes the piston 32 in the direction of reducing the capacity of the oil chamber 45. As a result, the device can be made compact reducing an installing space.

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, which have a container filled with high-pressure gas, or spring piston type accumulators, which have a piston 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 volume fluctuations are transmitted as density fluctuations), and the 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 accumulator container 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 only a small installation space.

[Means for Solving the Problems] In order to achieve the above object, the axial flow type surge absorber 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, and is provided along the pipe axis. A main flow pipe for hydraulic oil having a different diameter portion where the outer diameter changes in a part of the direction, and a main flow pipe for hydraulic oil that is provided on the outer peripheral surface side of the main flow pipe so as to surround the different diameter portion so as to be slidable in the pipe axial direction. a 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 an oil chamber provided on the piston side. a spring that is interposed in a compressed state between the first spring seat provided on the main flow pipe side and the second spring seat provided on the main flow pipe side, and urges the piston in a direction to reduce the volume of the oil chamber; It is equipped with.

[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, causing the downstream It can prevent surge waves from being transmitted to the side.

[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 controls the flow rate of hydraulic oil according to the rotation speed of the engine 2. 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 device, 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 at the other end of the steering shaft 11.
is provided. 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 axis 1
6 drives a steering linkage (not shown).

The inside of the power cylinder 15 is partitioned into a first cylinder chamber 18 and a second cylinder chamber by a rack piston 17, and each cylinder chamber 18 and 19 is connected to an oil passage 21.
, 22 and the high pressure oil pipe 25 via the control valve 23.
and a return pipe 26. The high pressure oil pipe 25 is connected to the discharge side of the flow control valve 4 via an axial flow type surge absorber 30, which will be described later.

The control valve 23 is connected to the steering shaft 11
The hydraulic oil flow path is formed in accordance with the steering direction of the steering wheel. 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. As a result, an axial force is generated on the rack shaft 16 in the right direction in the drawing. Conversely, rack axis 1
Turn the steering wheel 1 so that 6 moves to the left side in the illustration.
3 is rotated, hydraulic oil from the high-pressure oil pipe 25 is sent into the second cylinder chamber 19 through the other oil passage 22, thereby generating an axial force on the rack shaft 16 in the left direction in the drawing.

An axial flow type surge absorber 30 is provided in the middle of the high pressure oil pipe 25. As shown in FIG. 2, the surge absorber 30 includes a main flow pipe 31 as a center stud connected to a high pressure oil pipe 25, a cylindrical piston 32, and a spring 3.
It is composed of 3 etc. At the outer periphery of the main flow pipe 31,
Two portions having different outer diameters, a large diameter portion 35 and a small diameter portion 36, are formed in the tube axis direction. 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. Further, a first spring seat 40 is provided on one end side of the main flow pipe 31.

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 of the main flow pipe 31 so as to surround the different diameter portion 37, and this piston 32 is slidable in the axial direction of the main flow pipe 31. . Seal members 42 and 43 such as O-rings are 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.

The annular oil chamber 45 is connected to the inner peripheral surface of the piston 32 and the different diameter portion 3.
7 and the outer circumferential surface of the main flow pipe 31, and this oil chamber 45 is located at a position surrounded by the outer circumferential surface of the main flow pipe 31 including
It communicates with the inside of the main flow pipe 31 through 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 is connected to the oil chamber 4
The piston 32 is urged in a direction that reduces the volume of the piston 5 (leftward in FIG. 2). The spring 33 may be a coil spring with a constant pitch, but it is preferable to use a coil spring with an unequal pitch as illustrated in FIG. 3, so that as the load increases, the amount of close contact between the wires increases and the spring constant becomes non-linear. It may also be made to increase accordingly.

Next, the operation of the power steering device 1 including the in-line surge absorber 30 having the above configuration will be explained.

When the engine 2 rotates, the hydraulic oil discharged by the rotation of the vane pump 3 flows from the flow control valve 4 through the main flow pipe 31 and high pressure oil pipe 25 of the in-line surge absorber 30 to the control valve 23, and then flows into the control valve 23 through the return pipe 26. After that, return to reservoir tank 8. While the engine 2 is rotating, some parts of the oil pressure are above the standard level (for example, 50 to 120).
(any pressure value in a pressure range of about υf/d) acts on the high pressure oil pipe 25. In the axial flow type surge absorber 30, part of the hydraulic oil flowing through the main flow pipe 31 flows through the hole 46.
In order to flow into the oil chamber 45 through the oil chamber 45, 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 inside the main flow pipe 3 and the reaction force of the spring 33 are balanced. The area of the piston pressure receiving part 48 is the outer diameter cross-sectional area of the large diameter part 35 and the small diameter part 3.
It is expressed as the difference between the outer diameter cross-sectional area of 6.

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) depending on the steering direction of the steering shaft 11. As a result, the axial force of the rack shaft 16 is reduced to the right or left. Due to the movement of the rack piston 17, the second cylinder chamber 19
(or the first cylinder chamber 18) is returned to the reservoir tank 8 via the control valve 23 and 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. Since the volume change of the hydraulic oil due to the surge wave acts on the oil chamber 45 through the hole 46 of the surge absorber 130, the piston 32 moves in the axial direction of the main flow pipe 31 with the reference position as a boundary. 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 I valve 23 and power cylinder 15 side. The power steering device of this embodiment, which has this axial flow type surge absorber by 3 o"cm, has a significantly lower pulsating pressure than a conventional product that does not have a surge absorber.
Along with this, the generation of vibration and noise in the piping system has also decreased.

The axial flow type surge absorber 30 allows the entire flow rate 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 requires only a small space. 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, a large diameter portion 35 is formed by enlarging a part of the main flow pipe 3 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.

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

[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 pressure [), 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. ＼ Applicant's agent Patent attorney Takehiko Suzue Figure 3

Claims (3)

[Claims] (1) The main stream of hydraulic oil that is installed in the middle of an oil path that connects the discharge side of a hydraulic power source that generates hydraulic pressure and equipment that is moved by hydraulic pressure, and that has a portion with a different diameter where the outer diameter changes in a part of the pipe axis direction. a cylindrical piston that is slidably provided in the tube axis direction on the outer peripheral surface side of the main flow pipe so as to surround the different diameter portion; an inner surface of the piston and an outer peripheral surface of the main flow pipe; a first spring seat provided on the piston side and a second spring seat provided on the main flow pipe side; An axial flow type hydraulic surge absorber comprising: a spring which is interposed in a compressed state between a spring seat and urges the piston in a direction to reduce the volume of the oil chamber. (2) The shaft 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. Flow type hydraulic surge absorption device. (3) Claim 1, wherein the spring is an unequal pitch coil spring.
The axial flow type hydraulic surge absorption device described.