JPH0432228Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention can be attached to the tip of a hydraulic power shovel, etc., and can be used for demolition of concrete structures, crushing of rocks, etc.
This invention relates to a hydraulically operated impact power tool used for rock excavation, etc.

[Conventional technology]

In a hydraulically operated impact power tool, immediately after the piston hits the chisel, the piston rebounds rapidly, resulting in strong surge pressure in the low-pressure pipe line. This can cause damage to the hose/pipe retainer and oil cooler element on the low pressure side of the hydraulic power shovel. In order to prevent this, conventionally a single accumulator filled with nitrogen gas was used.
As shown in Japanese Patent No. 59-192472, it was attached to one side of the outer surface of the cylinder of a hydraulic impact power tool.

[Problem that the invention attempts to solve]

When an accumulator like the one mentioned above is connected to a low-pressure pipe, surge pressure can be absorbed and alleviated, but the nitrogen gas pressure of both the impact power tool and the accumulator must be checked during maintenance and inspection. No. Since the accumulator is attached to the outside of the tool, from the standpoint of safety, it must be installed in a position that does not come into contact with external reinforced concrete or rocks as much as possible, making it a difficult installation position for inspection and requiring time. . Also, in order to keep surge pressure as low as possible, it is advantageous to increase the gas pressure capacity of the accumulator, but with conventional methods, there are restrictions on mounting location and price.
It was difficult to install a large accumulator.

The present invention aims to solve these problems.

[Means for solving problems and their effects]

In order to solve the above problems, in the present invention, the accumulator is installed inside the sill of the impact power tool, the oil chamber side of the accumulator is connected to the low pressure pipe, and the gas chamber side is connected to the impact power tool's sill. It is connected to an upper chamber filled with gas.

[Effect]

When the piston hits the chisel and rebounds rapidly, the oil in the middle chamber (the chamber on the lower side of the piston's large diameter) is rapidly pushed out toward the low-pressure pipe, preventing smooth flow to the oil drain port. A very high surge pressure is generated, and a part of the oil pushed out from the middle chamber flows into the oil chamber of the accumulator branched from the low-pressure pipe, and the gas in the upper chamber flows through the diaphragm. It is alleviated by compressing the .

Next, in the rising process of the piston, the piston slowly rises while compressing the gas in the upper chamber, so the oil in the oil chamber of the accumulator is discharged by the gas pressure in the upper chamber, and the accumulator returns to its initial state. Return. While the impact power tool is operating, repeat the above operation to relieve the surge pressure.

〔Example〕

In FIG. 1, 1 is an impact power tool, 2 is a cylinder, and a piston 3 is slidably built into the cylinder 2. As shown in FIG. Hereinafter, the impact power tool will be referred to as a tool.

The piston 3 has an upper small diameter part 4 and a lower small diameter part 5 having the same diameter on the upper and lower sides, and a large diameter part 6 in the center.
are formed into one.

Inside the cylinder 2, a middle chamber 7 and a lower chamber 8 are formed, which are separated by the upper and lower surfaces of the large diameter portion 6 of the piston, and an upper chamber is provided above, through which the upper end of the upper small diameter portion 4 of the piston is inserted. and filled with nitrogen gas. A valve 43 for injecting and inspecting nitrogen gas into the upper chamber 9 is installed in the upper part of the cylinder 2. This valve 43 consists of a valve 41 and a spring 40 pushing it outward, and the inlet is connected to a cover nut 42.
This prevents dust from entering from outside and nitrogen gas from leaking from inside. A chisel 10 is fitted to the lower end of the cylinder 2 so as to be slidable within a certain range, so that the upper end of the chisel 10 is struck by the lower end of the piston 3.

Note that inner circumferential grooves 12, 13, 14 are formed from above in the portion on which the large diameter portion 6 of the piston 3 of the cylinder 2 slides.
will be established.

When the piston 3 is in the lowered position, the inner circumferential groove 1
2 and 13 are in communication, inner circumferential grooves 13 and 14 are blocked, and when the piston is in the raised position, inner circumferential groove 1
3 and 14 communicate with each other, and inner circumferential grooves 12 and 13 are cut off.

15 is a valve box fixed to one side of the cylinder 2;
A valve chamber 11 is provided within this valve box 15, and a valve 16 is slidably fitted therein.

A chamber 17 is provided in the upper part of the valve chamber 11, into which a plunger 18 is slidably fitted, and the lower end of the plunger 18 is brought into contact with the upper end of the valve 16. Valve 1
6 has a large diameter part 19 at the top and a small diameter part 31 at the bottom, and is fitted into the large diameter part and the small diameter part of the valve chamber 11 so as to be able to move forward and backward, and between the lower end surface of the large diameter part 19 and the valve chamber 11. An actuate chamber 34 is formed therein.

The valve 16 has an outer circumferential groove 2 below the small diameter portion 31.
0, and a communication hole 21 that communicates the upper and lower parts of the valve chamber 11 is formed in the axial center. Note that the difference in cross-sectional area between the large diameter portion and the small diameter portion is formed to be larger than the cross-sectional area of the plunger 18.

In the large diameter part of the valve chamber 11, an inner circumferential groove 22,
23, and inner circumferential grooves 24, 25, 2 are formed in the small diameter part.
form 6. The upper part of the valve chamber 11 communicates with the inner circumferential groove 12 of the cylinder 2 through an oil passage 27.
The inner circumferential grooves 13 and 14 of the cylinder each have an oil passage 2
8 and 29 communicate with the inner circumferential grooves 23 and 26 of the valve chamber 11.

A small diameter oil passage 30 that branches off in the middle of the oil passage 28 is
It communicates with the inner circumferential groove 24 .

32 is a low-pressure oil drain port, which communicates with the inner circumferential groove 22;
33 is an oil filler port, which is connected to the inner circumferential groove 25 and the chamber 17 by an oil passage.
communicate with.

An accumulator 35 is mounted inside the cylinder 2 with screws, bolts, or the like. (Illustration omitted) The accumulator has an oil chamber 36 and a gas chamber 37 that are partitioned inside by a rubber diaphragm 38.
The oil chamber 36 is connected to the upper part of the valve chamber 11 through an oil passage, and the gas chamber 37 is connected to the upper chamber 9 through a pore 39.

Next, the operation will be explained.

In FIG. 1, both the piston 3 and the valve 16 are in the lowered position, and when pressure oil is supplied to the oil supply port 33 in this state, the pressure oil flows from the inner circumferential groove 25 → the outer circumferential groove 20 → the inner circumferential groove 2.
6→oil passage 29→lower chamber 8, and hydraulic pressure is applied to the lower end surface of the large diameter portion 6 of the piston 3. At this time, Nakamuro 7 is
Since the piston 3 communicates with the oil passage 27 → the upper part of the valve chamber 11 → the inner circumferential groove 22 → the oil drain port 32, the piston 3 rises while compressing the nitrogen gas in the upper chamber 9. On the other hand, fuel filler port 3
Pressure oil also flows into the chamber 17 from the plunger 18
Since the valve 16 is pressed downward, the valve 16 is also pressed downward.

Next, when the piston 3 further rises and the lower end surface of the large diameter portion 6 communicates the inner circumferential groove 13 with the lower chamber 8, the pressure oil in the lower chamber 8 flows from the inner circumferential groove 13 to the oil passage 28 to the actuate chamber 34. As a result, hydraulic pressure acts on the lower end surface of the large diameter portion 19 of the valve 16.

This active area of the valve 16 is the same as that of the plunger 18.
valve 16 begins to move upwards.

At the same time when the displacement of the valve 16 reaches a certain value, the inner circumferential grooves 25 and 26 are blocked, and the inner circumferential grooves 24 and 25,
The inner circumferential groove 26 and the lower part of the valve chamber 11 communicate with each other, and the lower chamber 8 connects with the oil passage 29 → the inner circumferential groove 26 → the lower part of the valve chamber 11 → the communication hole 21 → the oil drain port 32 and the middle chamber 7. As the pressure in chamber 8 decreases, the pressure of the compressed nitrogen gas in upper chamber 9 causes the piston to begin to descend.

Even if the lower end of the large diameter portion 6 of the piston blocks the inner circumferential groove 13 from the lower chamber 8 during its descent, pressure oil will not flow into the inner circumferential groove 24.
→ Small-diameter oil passage 30 → Oil passage 28 → Actuate chamber 34 as the oil continues to be supplied, so the valve 16 continues to rise.

Therefore, the oil in the lower chamber 8 of the piston 3 smoothly flows out to the oil drain port 32 and the middle chamber 7, and the piston 3 strikes the chisel 10 due to the expansion force of the nitrogen gas.

After the impact, the piston 3 rebounds rapidly, so the oil in the middle chamber 7 is rapidly compressed and a surge pressure is generated.
At this time, a part of the oil discharged from the middle chamber 7 to the oil drain port 32 flows into the oil chamber 36 of the accumulator from the upper part of the valve chamber 11 and drains the nitrogen gas in the gas chamber 37 via the diaphragm 38. Since it is compressed, the peak value of the surge pressure is alleviated accordingly.

Note that if the diameter of the pores 39 is too large, the diaphragm may strongly hit the wall of the gas chamber 37 and bite into the pores 39. The pressure must be selected to such an extent that the pressure increases and the rate of displacement of the diaphragm is suppressed.

Immediately before the piston 3 hits the chisel 10, the upper end surface of the large diameter portion 6 of the piston 3 contacts the middle chamber 7 and the inner circumferential groove 1.
3, the oil in the actuate chamber 34 flows through the oil passage 28 → inner circumferential groove 13 → middle chamber 7 → inner circumferential groove 12.
→ Oil passage 27 → Inner circumferential groove 22 → Oil flows out from the upper part of the valve chamber 11 to the oil drain port 32.

Then, due to the pressing force of the plunger 18, the valve 1
6 begins to descend, and immediately after the piston 3 rebounds, the valve 16 returns to the lowered position shown in FIG.

By the way, the pressure in the middle chamber 7 when the piston is rising is determined by the loss of the pipe from the middle chamber 7 to the tank of the power shovel, the flow rate of oil, viscosity, etc.

Further, the rising speed of the piston 3 is determined by the discharge amount of the pump of the power shovel, but it is very slow compared to the striking speed, and the pressure in the middle chamber 7 does not rise much. Therefore, the diaphragm 38 of the accumulator 35 is pushed back from the position from which it was displaced when the piston 3 was rebounded by the nitrogen gas pressure.
The oil in the oil chamber 36 is discharged to the upper part of the valve chamber 11, and the initial state is restored. As long as pressure oil is supplied from the oil supply port 33, the above operation is repeated.

[Effect of idea]

Since this invention connects the upper chamber of the tool and the gas chamber of the accumulator, it is easier to check the gas pressure of the tool and the gas pressure of the accumulator separately compared to when the conventional accumulator is installed alone. There is no need to worry about having to do this, and if you only check the gas pressure of the tool, you have also checked the gas pressure of the accumulator, making maintenance and inspection easier.

Furthermore, in order to suppress the surge pressure as low as possible when the piston rebounds, it becomes necessary to increase the capacity of the gas chamber of the accumulator.

In this invention, the capacity of the upper chamber of the tool can also be considered as the capacity of the gas chamber of the accumulator, so even though the accumulator itself is small, it acts as a large capacity accumulator and suppresses surge pressure. Demonstrates the effect of keeping it low.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the tool of the present invention. 1... Impact power tool, 2... Cylinder, 3... Piston, 6... Large diameter section, 7... Middle chamber, 8... Lower chamber, 9... Upper chamber, 10... Chisel, 11... Valve chamber, 16... Valve, 32... Oil drain port, 33...
Oil supply port, 34... actuate chamber, 35... accumulator, 36... oil chamber, 37... gas chamber, 38... diaphragm, 39... pore, 43
……valve.

Claims (1)

[Scope of utility model registration request] A chisel 10 is attached to the lower end of the valve so that the chisel 10 can move forward and backward, and a valve 16 is installed in a valve box 15 that is attached to one side of the cylinder 2.
A hydraulic shock motion system in which a piston 3 is slidably built into the cylinder 2 and is pushed up by hydraulic pressure when rising and accelerated by the expansion force of nitrogen gas sealed in the upper chamber 9 when falling. In the tool, an accumulator 35 is disposed in the middle of the pipe connecting the upper chamber 9 and the oil drain port 32, and the gas chamber 3 of the accumulator is
7 side is connected to the upper chamber 9, and the oil chamber 36 side is connected to the oil drain port 32.
A hydraulic impact power tool characterized by being connected to a conduit leading to.