JPH0957649A - Hydraulic hammering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency by lessening leakage of a pressure oil. SOLUTION: A cylinder 2 is provided with a piston 1 having a major diametric portion 1B in the middle so that a front chamber 3 and a rear chamber 4 are formed, and the front chamber 3 is put in communication with a high pressure circuit 5 while the rear chamber 4 is put in communication with the circuit 5 and a low pressure circuit 8 alternately through a selector valve 7 so that the piston 1 is advanced and retreated. Thus a hydraulic hammering device is accomplished, in which a valve advance control port 13 connected through a valve control circuit 12 with a valve control chamber 11 to change over the position of the valve 7 from advance to retreat and vice versa is installed in a place which is in communication with the front chamber 3 when the piston 1 retreats. Behind this place, a valve retreat control port 14 connected with the valve control chamber 11 through the circuit 12 and an oil exhaust port 15 in communication with the low pressure circuit 8 are installed apart from each other at the bore of the cylinder 2 on the same cross-section thereof, and the major diametric portion 1B of piston 1 is furnished with a ring-shaped oil exhaust groove 16 which puts the control port 14 in communication with the exhaust port 15 when the piston 1 advances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic hammering device used in a hydraulic rock drill, a hydraulic breaker, or the like.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic striking device, as shown in FIG. 4, a large diameter portion 1B is provided at the center and small diameter portions 1A and 1C are provided before and after it.
The piston 1 having the above is slidably fitted in the cylinder 2 to form the front chamber 3 and the rear chamber 4, and the front chamber high-pressure port 6 for connecting the front chamber 3 to the high-pressure circuit 5 and the forward / backward switching of the switching valve 7 are performed. A rear chamber high pressure port 9 and a rear chamber low pressure port 10 for respectively communicating the rear chamber 4 with the high pressure circuit 5 and the low pressure circuit 8 are provided, and the valve control circuit 11 is provided in the valve control chamber 11 for switching the switching valve 7 between forward and backward movement.
A valve advancing control port 13 connected to the valve advancing control port 13 is provided at a position communicating with the antechamber 3 when the piston 1 is advancing, and is separated by a predetermined distance behind the advancing valve and connected to the valve control chamber 11 by the valve control circuit 12. The control port 14 is provided, and the valve reverse control port 1
4 is provided with a drain oil port 15 which is communicated with the low pressure circuit 8 at a predetermined distance from the rear of the piston 4, and an oil drain groove 16 which allows the valve reverse control port 14 and the drain oil port 15 to communicate with each other when the piston 1 moves forward is formed in the piston. The one provided on the outer periphery of the large diameter portion 1B of No. 1 is used.

In the hydraulic striking device of FIG. 4, a valve plug 17 is fitted in the cylinder 1 to form a valve chamber 18 concentric with the piston 1 between the outer circumference of the valve plug 17 and the inner circumference of the cylinder 2. The cylindrical switching valve 7 is slidably fitted in the valve chamber 18. The valve chamber 18 is provided with a valve regulation chamber 19 that communicates with the high pressure circuit 5 and biases the switching valve 7 rearward.
The front end portion and the rear end portion of are always in communication with the low voltage circuit 8.

In this hydraulic striking device, the rear chamber 4 is connected to the rear chamber high-pressure port 9 through the oil supply hole 20 when the switching valve 7 is in the front, so that the rear chamber 4 and the front chamber 3 both have high pressure. It communicates with the circuit 5. Since the pressure receiving area on the rear chamber 4 side of the piston 1 is larger than the pressure receiving area on the front chamber 3 side, the piston 1 moves forward. In this state, the valve forward control port 13 is opened to the front chamber 3 side, and the valve backward control port 14 is closed by the large diameter portion 1B of the piston 1, so the valve control circuit 12
The valve control chamber 11 that communicates with the front chamber 3 via the valve has a high pressure. Therefore, both the valve control chamber 19 and the valve control chamber 11 have high pressure, and the pressure receiving area on the valve control chamber 11 side is the valve control chamber 1
Since it is larger than the pressure receiving area on the 9 side, the switching valve 7 is held forward.

When the piston 1 advances, the valve advance control port 13 is closed at the large diameter portion 1B of the piston 1, and the valve reverse control port 14 communicates with the oil drain port 15 through the oil drain groove 16, so that the valve control is performed. The circuit 12 and the valve control chamber 11 have a low pressure. At this time, the valve regulation chamber 19 remains at a high pressure,
The switching valve 7 is retracted. When the switching valve 7 moves backward, the oil supply hole 20
Closed and the oil drain hole 21 opened, and the rear chamber 4 becomes the rear chamber low-pressure port 1
It communicates with the low voltage circuit 8 via 0. Piston 1 advanced
Hits the rear end of the rod 22 to stop the forward movement,
Starts to retreat because of low pressure.

When the piston 1 retracts, the valve advancing control port 13 is opened to the front chamber 3 side and the valve advancing control port 14 is closed by the large diameter portion 1B of the piston 1, so that the valve control circuit 1
The valve control chamber 11 communicating with the front chamber 3 via 2 becomes high pressure again and the switching valve 7 advances. When the switching valve 7 advances, the rear chamber 4 communicates with the high pressure circuit 5 via the rear high pressure port 9, the pressure in the rear chamber 4 rises, and the piston 1 that tries to continue the retreat due to inertia is braked, The retreat kinetic energy is stored in an accumulator (not shown) in the form of high pressure oil. The piston 1 that has stopped retreating again enters the forward stroke, and the same cycle is repeated thereafter.

[0007]

In this hydraulic striking device, both the front chamber 3 side and the rear chamber 4 side are at high pressure when the piston 1 moves forward, so that the pressure receiving area on the front chamber 3 side and the rear chamber 4 side are high. When the piston 1 moves backward, the front chamber 3 side has a high pressure and the rear chamber 4 side has a low pressure. Therefore, the piston 1 moves backward due to the oil pressure acting on the front chamber 3 side.

This forward / backward reciprocating motion is 2000 to 30
Since it may reach up to 00 times / minute, some clearance is required between the piston 1 and the cylinder 2, and the performance of the striking device depends on the size of this clearance. In the conventional hydraulic impact device, a long oil discharge groove 16 is provided in the front and rear for switching the switching valve 7 by connecting the valve reverse control port 14 and the oil discharge port 15 which are provided apart from each other in the front-rear direction by a predetermined distance. Since it is provided on the outer circumference of the large-diameter portion 1B of 1, the part of the pressure oil supplied to the front chamber 3 side and the rear chamber 4 side of the piston 1 passes through the clearance between the piston 1 and the cylinder 2. Leakage easily occurs from the oil drain groove 16 to the low-voltage circuit 8 side, resulting in low efficiency. In addition, the length of the piston 1 must be increased in order to provide the oil drain groove 16, and the hydraulic impact device must be increased in size.

The present invention is intended to solve such a problem of the hydraulic striking device, in which the leakage of the pressure oil from the oil drain groove is reduced to improve the efficiency, and the length of the piston is shortened to reduce the size. An object of the present invention is to provide a hydraulic impact device that can be realized.

[0010]

According to the present invention, a front chamber and a rear chamber are formed by slidably fitting a piston having a large diameter portion in the center and a small diameter portion in the front and rear thereof in a cylinder, and the front chamber is a high voltage circuit. A high pressure port in the front chamber for communicating with the high pressure circuit and a low pressure circuit in the rear chamber for communicating the rear chamber with a high pressure port for the rear chamber and a low pressure port for the rear chamber, respectively. In a hydraulic percussion device that moves the piston forward and backward by alternately communicating with the circuit, the valve forward control port connected by the valve control circuit to the valve control chamber that performs forward and backward switching of the switching valve The valve reverse control port connected to the valve control chamber by the valve control circuit and the drain oil port communicating with the low pressure circuit are provided at a position that communicates with the chamber and a predetermined distance behind the inner periphery of the same cross section of the cylinder. On top of each other And solves the above problems of the hydraulic striking device by providing an annular oil discharge groove communicating the valve backward control port and oil discharge port to the outer periphery of the piston of the large diameter portion when the piston moves forward.

By disposing a plurality of valve reverse control ports and a plurality of oil discharge ports at positions symmetrical with respect to the axis of the cylinder, the piston is less biased and a smooth forward / backward movement is possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a longitudinal sectional view of a hydraulic striking device according to an embodiment of the present invention, and FIGS. 2 and 3 show arrangements of a valve reverse control port and an oil discharge port in a transverse section. It is an explanatory view shown. FIG. 2 shows a state in which the piston moves backward, and FIG. 3 shows a state in which the piston moves forward. The basic structure of the hydraulic striking device of the present invention is similar to that of the conventional hydraulic striking device shown in FIG. The valve plug 17 is fitted. Rod 2 in front of piston 1
2 is inserted.

The piston 1 has a large-diameter portion 1B in the center, a small-diameter portion 1A in the front thereof, and a small-diameter portion 1C in the rear thereof, and a front chamber 3 and a rear chamber 4 are formed due to the difference in diameter. The rear small-diameter portion 1C has a smaller diameter than the front small-diameter portion 1A, so that the piston 1 has a larger pressure receiving area on the rear chamber 4 side than on the front chamber 3 side. The cylinder 2 has a front chamber 3 and a high-voltage circuit 5
Front chamber high-pressure port 6 that communicates with the rear chamber 4 and high-voltage circuit 5
And high-pressure port 9 in the rear room for communicating with the low-voltage circuit 8 and
And a rear room low pressure port 10 are provided.

The valve plug 17 fitted to the rear portion of the cylinder 2 has a front outer diameter reduced to form a valve chamber 18 between the outer circumference thereof and the inner circumference of the cylinder 2. A cylindrical switching valve 7 is slidably fitted in the valve chamber 18 concentrically with the piston 1. In the valve chamber 18, a valve control chamber 11 for switching the control valve 7 between forward and backward, and a high pressure circuit 5. A valve regulation chamber 19 that communicates with the valve chamber 7 and biases the switching valve 7 rearward is provided, and a front end portion and a rear end portion of the valve chamber 18 are always communicated with the low pressure circuit 8. Further, the switching valve 7 has an oil supply hole 20 for communicating the rear chamber 4 with the rear chamber high pressure port 9 when moving forward, an oil drain hole 21 for communicating the rear chamber 4 with the rear chamber low pressure port 10 when moving backward, and a valve control chamber. A control hole 23 for communicating the valve control circuit 11 with the valve control circuit 12 is provided.

Further, in the cylinder 2, a valve advancing control port 13 connected by a valve control circuit 12 to a valve control chamber 11 for switching the control valve 7 between forward and backward movement is communicated with the front chamber 3 when the piston 1 moves backward. The valve reverse control port 14 connected to the valve control chamber 11 by the valve control circuit 12 and the drain oil port 15 communicating with the low pressure circuit 8 are provided at a predetermined position behind the cylinder 2. They are spaced apart from each other on the inner circumference of the same cross section. On the outer circumference of the large diameter portion 1B of the piston 1, an annular oil drain groove 16 that connects the valve reverse control port 14 and the oil drain port 15 when the piston 1 moves forward
Is provided.

As shown in FIGS. 2 and 3, here, the valve reverse control port 14 is provided at two locations on the left and right, and the oil drain ports 15 are provided at two locations above and below, but the number thereof is as required. It can be set arbitrarily. In that case, if a plurality of valve reverse control ports 14 and a plurality of oil drain ports 15 are respectively arranged at positions symmetrical with respect to the axis of the cylinder 2, the piston 1 will be less biased and a smooth forward / backward movement will be possible. become.

In this hydraulic striking device, the rear chamber 4 communicates with the rear high-pressure port 9 through the oil supply hole 20 when the switching valve 7 is in the front, so that the rear chamber 4 and the front chamber 3 both have high pressure. It communicates with the circuit 5. Since the pressure receiving area on the rear chamber 4 side of the piston 1 is larger than the pressure receiving area on the front chamber 3 side, the piston 1 moves forward. In this state, the valve advancing control port 13 is opened to the front chamber 3 side, and the valve backward advancing control port 14 is closed by the large diameter portion 1B of the piston 1 as shown in FIG. The valve control chamber 11 that communicates with the front chamber 3 via the valve has a high pressure. Therefore, the valve control chamber 19 and the valve control chamber 11 are both high in pressure, and the pressure receiving area on the valve control chamber 11 side is larger than the pressure receiving area on the valve control chamber 19 side.
The switching valve 7 is held forward.

When the piston 1 advances, the valve advance control port 13 is closed at the large diameter portion 1B of the piston 1, and the valve reverse control port 14 is connected to the oil drain port 15 via the oil drain groove 16 as shown in FIG. Since they communicate with each other, the valve control circuit 12 and the valve control chamber 11 have a low pressure. At this time, the valve control chamber 19 is still at high pressure, so the switching valve 7 is retracted. When the switching valve 7 retracts, the oil supply hole 20 closes and the oil discharge hole 21 opens, so that the rear chamber 4 communicates with the low pressure circuit 8 via the rear chamber low pressure port 10. The advanced piston 1 strikes the rear end of the rod 22 to stop the advance, and starts the retreat because the rear chamber 4 has a low pressure.

When the piston 1 retreats, the valve advancing control port 13 is opened to the front chamber 3 side and the valve advancing control port 14 is closed by the large diameter portion 1B of the piston 1, so that the valve control circuit 1
The valve control chamber 11 communicating with the front chamber 3 via 2 becomes high pressure again and the switching valve 7 advances. When the switching valve 7 advances, the rear chamber 4 communicates with the high pressure circuit 5 via the rear high pressure port 9, the pressure in the rear chamber 4 rises, and the piston 1 that tries to continue the retreat due to inertia is braked, The retreat kinetic energy is stored in an accumulator (not shown) in the form of high pressure oil. The piston 1 that has stopped retreating again enters the forward stroke, and the same cycle is repeated thereafter.

In the conventional hydraulic impact device, if the outer diameter of the large diameter portion 1B of the piston is D _P , the inner diameter of the cylinder 2 is D _C , and the cross-sectional area of the clearance is S _C , then S _C = π (D _C ² − D _P ² ) / 4 ... (1) Since the front chamber 3 and the rear chamber 4 are at high pressure when the piston 1 moves forward, the flow passage area of the leaking pressure oil at this time is defined as S ₁ . Then, S ₁ = 2SC _C (2) When the piston 1 moves backward, only the front chamber 3 has a high pressure. Letting the flow path area be S ₂ , S ₂ = S _C (3)

On the other hand, in the hydraulic impact device of the present invention, when the clearance is large, the flow passage area S ₃ of the leaking pressure oil is the cross-sectional area of the oil discharge port 15, so the diameter of the oil discharge port 15 is d. Then, the oil drain port 1 at the N location
If there are 5, when the ^{_{S 3 = Nπd 2/4 ·············}} (4) the clearance is small, the flow passage area S ₄ of the pressure oil to leak, the oil discharge port 15 Since it is the product of the peripheral length and the width of the clearance, S ₄ = Nπd (D _C −D _P ) / 2 ... (5).

Therefore, as an example, the leaking pressure oil passage area S ₁ of the conventional hydraulic striking device and the leaking pressure oil passage area S ₄ of the hydraulic striking device of the present invention are D _P = 100 mm When calculation is performed for the case of D _C -D _P = 0.2 mm d = 5 mm N = 2, S ₁ = 62.9 mm ² from the equation (2), S ₄ = 3.14 mm ² from the equation (5).

In general, the flow rate Q of the pressure oil passing through the flow passage area S at the pressure difference P can be approximately calculated by Q = kPS, where k is a coefficient depending on the shape of the flow passage. Assuming that the conventional hydraulic striking device and the hydraulic striking device of the present invention have substantially the same coefficient k, S ₄ / S ₁ = 0.05. Therefore, in the present invention, the pressure oil leaking from the drain groove 16 is used. The amount of leakage is reduced to about 5% compared to the conventional hydraulic impact device.

Therefore, the efficiency of this hydraulic striking device is greatly improved. Further, unlike the conventional case, it is not necessary to provide a long oil drain groove in the front and rear, so that the length of the piston 1 can be shortened and the hydraulic impact device can be downsized.

[0025]

As described above, in the hydraulic striking device of the present invention, the leakage of the pressure oil from the oil drain groove is reduced to improve the efficiency, and the length of the piston is shortened to reduce the size. be able to. Further, by disposing a plurality of valve reverse control ports and a plurality of oil discharge ports respectively at positions symmetrical with respect to the axis of the cylinder, it is possible to reduce the deviation of the piston and perform a smooth forward and backward movement.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a hydraulic impact device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a cross-sectional arrangement of a valve reverse drive control port and an oil discharge port.

FIG. 3 is an explanatory view showing a cross-sectional arrangement of a valve reverse drive control port and an oil discharge port.

FIG. 4 is a vertical sectional view of a conventional hydraulic impact device.

[Explanation of symbols]

 1 Piston 2 Cylinder 3 Front Chamber 4 Rear Chamber 5 High Pressure Circuit 6 Front Chamber High Pressure Port 7 Switching Valve 8 Low Pressure Circuit 9 Rear Chamber High Pressure Port 10 Rear Chamber Low Pressure Port 11 Valve Control Room 12 Valve Control Circuit 13 Valve Forward Control Port 14 Valve Reverse Control port 15 Oil drain port 16 Oil drain groove 17 Valve plug 18 Valve chamber 19 Valve regulation chamber 20 Oil drain hole 21 Oil feed hole

Claims (2)

[Claims] 1. A front chamber high-pressure port for communicating a front chamber with a high-voltage circuit by slidably fitting a piston having a large-diameter portion in the center and a small-diameter portion in the front and rear thereof in a cylinder to form a front chamber and a rear chamber. , A rear chamber high-pressure port and a rear chamber low-pressure port for connecting the rear chamber to the high-pressure circuit and the low-pressure circuit respectively, and the rear chamber is alternately switched to the high-pressure circuit and the low-pressure circuit by the forward and backward switching of the switching valve. Is a hydraulic striking device that moves the piston forward and backward, and the valve forward control port that is connected to the valve control chamber that switches the forward / backward movement of the switching valve by the valve control circuit is placed in a position that communicates with the front chamber when the piston moves backward. A valve reverse control port connected to the valve control chamber by a valve control circuit and a drain oil port communicating with the low pressure circuit are provided behind the predetermined distance from each other on the inner periphery of the same cross section of the cylinder. Installed and valve when piston moves forward A hydraulic striking device characterized in that an annular oil drain groove for communicating the reverse control port and the oil drain port is provided on the outer circumference of the large diameter portion of the piston. 2. The valve reverse control port and the oil drain port are
2. The hydraulic striking device according to claim 1, wherein a plurality of hydraulic striking devices are arranged at positions symmetrical with respect to the axis of the cylinder.