JP2813003B2 - Shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hydraulically operated impact power tool or pile which is attached to the tip of a hydraulic excavator or the like and used for demolition of concrete structures, crushing of rocks, rock excavation, etc. The present invention relates to an impact motion device used for a driving machine or the like.

[Conventional technology]

Hydraulically operated impact tools can be broadly divided into accumulator systems and gas systems.

The accumulator method is a method of accumulating oil in an accumulator when the piston rises, discharging the oil in a stroke, and accelerating the piston.

The gas method is used when the piston rises by hydraulic pressure,
This system is disclosed in Japanese Patent Publication No. Sho 54-32192, in which energy is accumulated by compressing the gas above the piston, and the piston is accelerated by utilizing the expanding energy of the gas during the impact stroke.

FIG. 4 shows a known gas-type impact moving tool described in the above-mentioned publication, and reference numeral 1 denotes a cylinder having a tool 2 such as a chisel attached to the lower end thereof so as to be able to advance and retreat.

The cylinder 1 has a large-diameter portion 3 at an intermediate portion, and a piston 4 that hits the tool 2 when descending is fitted therein. Gas pressure is applied to the upper surface of the raised piston 4 above the cylinder 1. An upper chamber 5 filled with gas is provided.

An intermediate chamber 6 and a lower chamber 7 are provided between the upper and lower small diameter portions of the large diameter portion 3 of the piston 4 and the inner circumference of the cylinder 1.

Reference numeral 8 denotes a valve chamber provided on a side portion of the cylinder 1 and a valve body 10 having a communication hole 9 in the center is fitted in the valve chamber.

The upper and lower portions of the valve chamber 8 and the lower portions of the middle chamber 6 and the lower chamber 7 are communicated with each other through oil passages 14 and 16, and the middle portion of the cylinder 1 and the middle portion of the valve chamber 8 are also in the middle of the oil passage 15 and the same oil passage. From the oil path that branches off.

A drain port 11 and a fuel filler port are provided near the upper and lower portions of the valve chamber 8.
The oil passage 12 communicates with the oil passage 12, and the oil passage communicating with the oil supply port 12 communicates with the rear part of the plunger 13 that pushes down the valve body 10.

In this known impact power tool, when the valve body 10 is at the lower limit as shown in FIG.
Since the middle chamber 6 communicates with the oil drain port 11, the piston 4 rises to compress the gas in the upper chamber 5.

When the lower end of the large-diameter portion 3 becomes higher than the oil passage 15 due to the rise of the piston 4, the oil supply port 12 leads to an oil passage that pushes up the valve body 10,
The valve body 10 is raised by the action of the hydraulic pressure, and the lower chamber 7 communicates with the oil discharge port 11 by the communication hole 9 of the valve body 10. Therefore, the piston 4 is lowered by the gas pressure of the upper chamber 5 and hits the tool 2. Perform the action.

[Problems to be solved by the invention]

In the conventional impact power tool that performs the above-described operation, in the step of striking the piston 4, the valve body 10 rises as described above and the lower chamber 7 communicates with the oil drain port 11, so that the piston 4 When the body rebounds violently immediately after the impact, the pressure in the lower chamber suddenly drops due to the rapid expansion of the volume of the lower chamber 7, and the so-called cavitation phenomenon occurs in which the bubbles contained in the hydraulic oil grow rapidly. I do.

Next, when the valve element 10 descends and the pressure oil flows into the lower chamber 7 and the pressure in the lower chamber rises, the grown bubbles collapse instantaneously, generating a very high pressure and a shock wave.

Since this phenomenon is repeated several hundred times per minute, erosion occurs on the inner surfaces of the piston 4 and the cylinder 1 when the impact power tool is used for a long time.

An object of the present invention is to provide an impact moving device that prevents the occurrence of the cavitation phenomenon as described above, eliminates erosion that occurs on the surfaces of the piston 4 and the cylinder 1, and improves durability. It is.

[Means for solving the problem]

In order to solve the above-described problems, the present invention provides a piston having a large-diameter portion in an intermediate portion in a cylinder, and providing a lower chamber on the inner periphery of the cylinder at a lower portion of the large-diameter portion of the piston. In a device in which a piston is moved up and down by hydraulic pressure or oil pressure and gas pressure, and a valve body is moved up and down by switching oil pressure in accordance with raising and lowering of the piston, a lower end communicates with the middle chamber and a lower chamber communicates with the bottom. A pressure adjusting chamber having an oil reservoir is provided, and a pressure adjusting piston is fitted in the pressure adjusting chamber, and a plunger at a lower end thereof is fitted into the oil reservoir, and an upper end of the pressure adjusting chamber is communicated with a drainage passage, Further, an impact power tool is provided in which an upper part of the pressure adjusting piston is provided with a projection having a smaller diameter than the piston, and the projection is freely movable up and down in a hydraulic chamber communicating with the oil supply passage.

In addition, a pressure adjustment chamber is provided in which the upper end communicates with the middle chamber and the lower chamber communicates with the bottom, and a pressure adjustment piston is fitted in the pressure adjustment chamber. The present invention also provides an impact device in which a projection is provided, and the projection is vertically movable into a pressure adjusting gas chamber communicating with an upper chamber filled with gas in the cylinder.

[Action]

Since the present invention has the above configuration, in the first invention, the valve body is at the lower limit, and when the piston is at the lowered position, the oil supply port and the lower chamber communicate with each other, and the middle chamber communicates with the oil discharge port. Ascends and compresses the gas in the upper chamber.

In addition, oil pressure flows into the lower end of the pressure adjustment chamber while the piston is rising, and pushes up the pressure adjustment piston against the oil pressure applied to the hydraulic chamber.

When the valve body rises by hydraulic pressure during the rise of the piston and the lower chamber communicates with the oil discharge port through the communication hole of the valve body, the piston suddenly descends due to the gas pressure of the upper chamber and hits the tool.

As described above, when the piston descends, the oil reservoir at the bottom of the pressure adjustment chamber communicates with the oil discharge port, and the pressure adjustment piston descends due to the oil pressure in the hydraulic chamber, and the plunger at the bottom of the piston adjusts the oil in the oil reservoir. Since the fluid flows into the lower chamber, there is no sudden drop in pressure due to the repulsion of the piston. Therefore, bubbles in the pressure oil in the lower chamber do not grow and cavitation does not occur.

Further, in the second invention, when the piston rises, the oil pressure in the lower chamber flows into the lower part of the pressure adjusting chamber, the upper part of the pressure adjusting chamber communicates with the oil drain port, and the pressure adjusting piston is moved into the pressure adjusting gas chamber. Is rising against the pressure of.

When the valve body rises by hydraulic pressure during the rise of the piston and the lower chamber communicates with the oil discharge port through the communication hole of the valve body, the piston suddenly descends due to the gas pressure of the upper chamber and hits the tool.

As described above, when the piston descends, the lower part of the pressure regulating chamber communicates with the oil discharge port, and the gas pressure of the pressure regulating gas chamber causes the pressure regulating piston to descend to lower the oil in the lower part of the pressure regulating chamber. Since it flows into the chamber, there is no sudden drop in pressure due to the repulsion of the piston, so that bubbles in the pressure oil in the lower chamber do not grow and cavitation does not occur.

〔Example〕

FIGS. 1 and 2 show the first embodiment, in which the cylinder 1 and the valve mechanism are the same as those of the conventional example of FIG. 4, but a pressure adjusting chamber 21 is provided separately from the cylinder 1.

An oil reservoir 22 having a small diameter is provided at the bottom of the adjustment chamber 21, and the lower end thereof is connected to the lower chamber 7 through an oil passage 23.

Reference numeral 24 denotes a pressure adjusting piston fitted in the chamber 21, and a projection 25 and a plunger 26 are integrally provided at an upper end and a lower end thereof.

Assuming that the diameter of the piston 24 is D, the diameter of the projection 25 is d ₁ , and the diameter of the plunger 26 is d ₂ , D> d ₁ > d ₂ and (D ² −d ₂ ² ) <d ₁ The condition of ² .

The plunger 26 is slidably fitted in the oil reservoir 22, and the projection 25 slidably penetrates a through hole in the upper part of the chamber 21 while maintaining liquid tightness, and projects into the hydraulic chamber 28.

In addition, oil passages 29 and 30 communicating with the lower and upper
Are connected to the lower end of the middle chamber 6 and the oil discharge port 11, respectively, and the hydraulic chamber 28 is connected to the oil supply port 12 through the oil passage 31.

In the case of the above embodiment, the operation of the piston 4 and the valve body 10 is the same as that of the conventional example shown in FIG.

Now, when the piston 4 is at the lower end as shown in FIG.
Since the lower chamber 7 communicates with the oil supply port 12, the oil pressure from the oil supply port 12 flows into the lower chamber 7 and the oil reservoir 22, and the upper and lower portions of the pressure adjustment chamber 21 communicate with the oil discharge port 11.

Accordingly, the piston 4 is raised, and the pressure adjusting piston 24 remains depressed by the hydraulic pressure applied to the projection 25 from the hydraulic chamber 28.

When the lower end of the large-diameter portion 3 comes to a position where the oil passages 15 and 16 communicate with each other as shown in FIG. It rises overcoming the hydraulic pressure applied to the upper surface of the projection 25.

As described above, the oil passages 15 and 16 communicate and the valve
When the valve 10 rises, the lower chamber 7 communicates with the oil discharge port 11 through the communication hole 9 of the valve body 10, and at the same time, the oil reservoir 22 at the bottom of the adjustment chamber 21 also has the oil discharge port 11.
Lead to.

Therefore, the piston 4 rapidly descends due to the gas pressure in the upper chamber 5 and strikes the tool 2.

As described above, the time from when the piston 4 starts descending and hits the tool 2 is 2 to 3/100 sec, and since the descending speed of the pressure adjusting piston 24 is lower than the descending speed of the piston 4,
When the piston 4 strikes the tool 2 and repels, the pressure adjusting piston 24 is still descending, and therefore the oil in the oil reservoir 22 is supplied to the lower chamber 7 by the descending plunger 26, and the lower chamber 7
Prevents a sharp drop in hydraulic pressure inside.

In this embodiment, the upper part of the pressure adjusting chamber 21 is provided with an oil passage 30 through an oil drain port.
Although it communicates with 11, it may communicate with the upper part of the middle chamber 6.

In the second embodiment shown in FIG. 3, the pressure adjusting piston 24 is not provided with a plunger, and the bottom of the pressure adjusting chamber 21 and the lower chamber 7 are connected to an oil passage.
Communicate directly at 23.

The protrusion 25 slidably penetrates the through hole at the upper part of the chamber 21 while maintaining liquid tightness, and projects into the pressure adjusting gas chamber 32.

The upper end of the gas chamber 32 communicates with the upper chamber 5 through a communication passage 33.

In this embodiment, the upper part of the middle chamber 6 and the upper part of the control chamber 21 are connected to an oil passage.
Connect with 34.

In the case of this embodiment, when the piston 4 is at the lower end as shown in FIG. 3, the lower chamber 7 communicates with the oil supply port 12, so that the oil pressure from the oil supply port 12 is lower than the lower chamber 7 and the pressure adjustment chamber 21. And the upper part of the adjustment chamber 21 communicates with the oil drain port 11 via the oil passage 34, the middle chamber 6, and the like.

Accordingly, the piston 4 rises, and the pressure adjusting piston 24 also rises, causing the pressure oil to flow into the lower part of the chamber 21.

When the piston 4 rises and the lower end of the large diameter portion 3 becomes a position for communicating the oil passages 15 and 16, the valve body 10 rises by hydraulic pressure, and when the lower chamber 7 communicates with the oil discharge port 11, the piston 4 moves to the upper chamber. The tool 2 descends rapidly by the gas pressure of 5 and hits the tool 2.

As described above, the lower chamber 7 communicates with the oil discharge port 11 and
Since the lower part of the adjustment chamber 21 is also communicated with the oil drain port 11 through the lower chamber 7 by the pressure chamber 23, the pressure adjustment piston 24 is controlled by the gas pressure of the gas chamber 32.
Falls, and the oil below the adjustment chamber 21 flows into the lower chamber 7.

Therefore, a sudden drop in pressure in the lower chamber 7 when the piston 2 is repelled by hitting the tool 2 is prevented.

In each of the following embodiments, for simplicity of explanation, a structure in which a piston is directly fitted in a cylinder is shown, but the cylinder in the present invention is a bush portion in which a piston is directly inserted, Needless to say, this includes a structure in which the bush portion is divided into a cylinder portion to house the bush portion.

In each of the above embodiments, the present invention is applied to an impact power tool. However, in a descending stroke such as a pile driving machine other than the impact power tool, an impact is applied to an object to perform some work. Widely available for equipment.

〔The invention's effect〕

According to a first aspect of the present invention, the pressure adjusting chamber having the oil reservoir is provided as described above, and the piston in the pressure adjusting chamber is pushed up in a stroke in which the piston in the cylinder rises, so that the oil reservoir is When the piston tool is hit and repelled, the pressure adjustment piston is pushed down by oil pressure and the oil in the oil reservoir flows into the lower chamber, causing a sudden drop in pressure in the lower chamber. To prevent Therefore, there is an effect of preventing the occurrence of cavitation.

Further, the invention described in the second claim is characterized in that when the piston rises, oil is accumulated in the lower part of the pressure regulating chamber, and when the piston descends and strikes a tool or the like and repels, the pressure regulating piston is pushed down by gas pressure. As a result, the oil in the lower part of the pressure adjustment chamber flows into the lower chamber, thereby providing an effect of preventing the occurrence of cavitation due to a sudden pressure drop in the lower chamber as in the first aspect of the invention.

Therefore, in any of the inventions, damage to the piston and the cylinder is significantly reduced, and the durability of the impact driving device is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view showing a first embodiment of the present invention, FIG. 2 is a longitudinal sectional front view showing an operation of a main part of the embodiment, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a longitudinal sectional front view of a conventional device, showing an embodiment. 1 ... cylinder, 3 ... large diameter part, 4 ... piston, 5 ... upper chamber, 6 ... middle chamber, 7 ... lower chamber, 8 ... valve chamber, 10 ... valve body, 11 ... Oil drain port, 12 Oil filler port, 13 Plunger, 21 Pressure adjustment chamber, 22 Oil reservoir, 24 Pressure adjustment piston, 25 Projection, 26 Plunger, 28 Hydraulic chamber, 32 ... Gas chamber for pressure adjustment.

Claims (2)

(57) [Claims] A piston having a large-diameter portion in an intermediate portion is fitted in a cylinder, a lower chamber is provided in an inner periphery of the cylinder below the large-diameter portion of the piston, and a cylinder is provided in an upper portion of the large-diameter portion. A lower chamber communicates with the inner chamber in a device in which an inner chamber is provided on the inner periphery of the valve, and the valve body is raised and lowered by raising and lowering the piston by hydraulic pressure or oil pressure and gas pressure, and switching hydraulic pressure accompanying the raising and lowering of the piston. A pressure adjusting chamber having an oil reservoir communicating with the lower chamber is provided at the bottom, and a pressure adjusting piston is fitted in the pressure adjusting chamber, and a plunger at the lower end of the pressure adjusting piston is fitted into the oil reservoir. The upper end communicates with the oil drainage passage, and furthermore, a projection having a smaller diameter than the piston is provided on the upper part of the pressure adjusting piston, and this projection is inserted into the hydraulic chamber communicating with the oil supply passage so as to be able to move up and down freely. . 2. A piston having a large-diameter portion at an intermediate portion thereof is fitted in a cylinder, a lower chamber is provided at an inner periphery of the cylinder below the large-diameter portion of the piston, and a cylinder is provided at an upper portion of the large-diameter portion. An inner chamber is provided on the inner periphery of the cylinder, and an upper chamber filled with gas is provided on the upper part of the cylinder. The upper part of the piston is inserted into this upper chamber so as to be able to move up and down, and it is possible to raise and lower the piston by hydraulic pressure and gas pressure, and to raise and lower the piston. In a device in which the valve body is moved up and down by switching of the accompanying oil pressure, an upper end communicates with the middle chamber, and a pressure adjusting chamber communicated with the lower chamber is provided at the bottom, and a pressure adjusting piston is fitted into this pressure adjusting chamber. An impact device in which a projection having a diameter smaller than that of the piston is provided at an upper portion of the pressure adjustment piston, and the projection is fitted in a gas chamber for pressure adjustment that communicates with an upper chamber filled with gas in the cylinder so as to be vertically movable. .