JPS6019196Y2 - Reciprocating switching device for impact piston in hydraulic impact tools - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a reciprocating switching device for a striking piston in a hydraulic striking tool such as a hydraulic rock drill.

Generally, in a hydraulic impact tool such as a hydraulic hammer Iwatsuki, in order to reciprocate the impact piston that is slidably fitted into a cylinder formed in the impact tool body, the impact piston is disposed coaxially with the axis of the impact piston within the cylinder. A substantially cylindrical switching valve is slidably provided, and the striking piston is switched between forward and backward movement by switching the switching valve.

However, in the conventional type, since the switching timing of the switching valve is controlled by a striking piston, the switching valve performs switching operation at a constant opening/closing speed and at a constant oil supply/discharge speed.
However, there are disadvantages in that it is difficult to reliably maintain the position of the valve after switching, and the operation of the valve is unstable, and a large amount of oil is required for switching the valve in order to obtain stable valve operation.

The present invention has been made in view of the above points, and it rapidly supplies and discharges oil to and from the switching valve at both the forward and backward ends of the impact piston in a hydraulic impact tool, that is, the switching valve is opened and closed immediately after the piston starts moving forward. By supplying waste oil from the valve to the rear chamber of the piston, the switching valve can be operated stably and reliably, and the amount of oil required to switch the valve can be reduced. It is an object of the present invention to provide a reciprocating switching device for a striking piston in a striking tool.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

1 to 4, reference numeral 1 denotes an impact tool body, and the impact tool body 1 is formed with a cylinder 2 having a front chamber 2a and a rear chamber 2b at the front and rear. A piston 3 is slidably fitted, and the striking piston 3
is formed with a front pressure surface 3a and a rear pressure surface 3b which always face the cylinder front chamber 2a and rear chamber 2b, and the rear pressure surface 3b is formed larger than the front pressure surface 3a, On the outer periphery of the striking piston 3, a front annular port 4 that communicates with the cylinder front chamber 2a near the forward end of the striking piston 3, and a rear annular port 5 located behind the front annular port 4 are formed in order. .

Note that 6 is a bit loft that is struck by the front end of the striking piston 3 when it is at its forward end.

7 is an oil chamber formed in the impact tool body 1; 8 and 9 are oil supply passages for the front chamber and rear chamber, each of which has one end communicating with the oil chamber 7; the other end of the oil supply passage 8 for the front chamber; is opened to a part of the cylinder front chamber 2a, and the other end of the rear chamber oil supply passage 9 is opened to a part of the cylinder rear chamber 2b via an oil passage opening/closing valve 10.

The oil passage opening/closing valve 10 is a substantially cylindrical valve that is slidably fitted into a valve rear chamber 11 formed in the impact tool body 1 so that its front end faces the rear chamber oil supply passage 9. , are provided so as to slide around the axis of the striking piston 3.

This valve 10 includes a rear chamber oil supply passage 9 and a valve rear chamber 1.
Front pressure surface 10a facing 1 (its area is A)
and a rear pressure surface 10b (the area of which is B), which is larger than the front pressure surface 10a (i.e., B>A), and the outer circumference of the front end of the valve 10 and Steps 12.13 are formed on the valve sliding surfaces of the cylinder rear chamber 2b, and these steps 12.13 allow the outer half surface 10c (its area is C) of the front pressurizing surface 10a of the valve 10 to be The rear chamber oil supply passage 9 is kept open at all times, and the remaining inner circumferential side half surface 10d (its area is D) is shut off and opened from the rear chamber oil supply passage 9 during the forward and backward movement of the valve 10. It is composed of

Further, a front piston 3c and a rear piston 3d are formed on the front and rear sides of the rear annular port 5 of the striking piston 3, and are separated by the rear annular port 5, and the outer diameter of the rear piston 3d is The inner diameter of the cylinder sliding part on which the rear piston 3d slides is larger than the outer diameter of the front piston 3c, and the inner diameter of the cylinder sliding part on which the front piston 3c slides corresponds to the outer diameter of the rear piston 3d. Therefore, a valve oil drain chamber 16 is formed in the rear annular port 5 by the steps 14 and 15 of the cylinder 2 and piston 3 formed before and after the rear annular port 5. .

Furthermore, 17 is a first oil passage, one end of which communicates with the front annular port 4 near the forward end of the piston 3, and communicates with the front chamber oil supply passage 8 via the front annular port 4. It is opened in the piston sliding surface of the cylinder 3 slightly behind the opening of the chamber oil supply passage 8, and the other end is opened in the valve rear chamber 11, so that the valve rear chamber 11 is opened near the forward end of the piston 3. It is provided so as to communicate with the front chamber oil supply path 8.

Reference numeral 18 denotes a cylinder oil drain passage connected to another part of the cylinder rear chamber 2b, and the opening of the oil drain passage 18 is opened and closed by the front end of the oil passage opening/closing valve 10. It is set in.

In addition, 19 is an auxiliary first oil passage, one end of which is opened in the rear piston sliding surface of the cylinder 2 so as to communicate with the valve oil drain chamber 16 near the retreating end of the piston 3, and the other The end thereof is connected to an intermediate portion of the first oil passage 17, so that the valve rear chamber 11 is communicated with the valve oil drain chamber 16 near the retreating end of the piston 3.

Further, 20 is a second oil passage, one end 20a of which is opened in the front piston sliding surface of the cylinder 2 so as to communicate with the valve oil drain chamber 16 immediately after the piston 3 starts moving forward. The end 20b is the valve forward end of the valve sliding surface of the cylinder rear chamber 2b (i.e., the part of the step 13)
Therefore, from immediately after the piston 3 starts moving forward until the other end opening 20b is closed by the front end (inner half surface 10d) of the valve 10 (that is, the piston 3
The valve oil drain chamber 16 is provided so as to communicate with the cylinder rear chamber 2b during the period (up to the forward end of the cylinder).

Note that 21 is an accumulator provided in the oil chamber 7.

Next, to explain its operation, first, as shown in FIG. 1, when the striking piston 3 advances and reaches near the forward end, the first oil passage 17 communicates with the front annular port 4 and 4 communicates with the cylinder front chamber 2a, so that the valve rear chamber 11 is connected to the first oil passage 17 and the front annular port 4.
The oil passage opening/closing valve 10 communicates with the front chamber oil supply passage 8 via the cylinder front chamber 2a and the rear pressure surface 10b.
and the area difference between the front pressure surface 10a (B-A=B-C-D)
The valve 10 moves forward rapidly due to the hydraulic pressure applied to it, and during the forward movement, the stepped portion 12 on the outer periphery of the front end of the valve 10 changes to the stepped portion 13 formed on the valve sliding surface of the cylinder rear chamber 2b.
At the same time, the cylinder rear chamber 2b communicates with the cylinder oil drain passage 18, so that only the outer peripheral side half surface 10c of the front pressurizing surface 10a of the valve 10 is opened to the rear chamber oil supply passage 9, and the supply oil pressure is As a result, the difference in area on which the supply oil pressure acts increases before and after the valve 10, that is, B-C (>B-C-D), and the valve 10 increases its forward speed and reaches its maximum stroke. At the same time, the piston 3 reaches the forward end position and strikes the bit rod 6, and then the supply pressure is applied only to the front pressurizing surface 3a of the piston 3. As a result, the piston 3 begins to retreat.

Then, as the piston 3 moves backward as shown in FIG. The volume of 16 increases due to the steps 14 and 15 before and after it, and this volume expansion creates a negative pressure state.

Furthermore, when the piston 3 retreats and reaches the vicinity of the backward end, the auxiliary first oil passage 19 communicates with the valve oil drain chamber 16 as shown in FIG. 17 and the valve oil drain chamber 1 via the auxiliary first oil passage 19.
6, the valve rear chamber 11 is connected to the valve rear chamber 11 by the suction action of the valve oil drain chamber 16 which is in a negative pressure or vacuum state as described above.
The oil supplied to the valve is sucked into the valve oil drain chamber 16 and flows into the valve oil drain chamber 16.

As a result, the supply oil pressure no longer acts on the rear pressure surface 10b of the valve 10, and the valve 10 rapidly retreats due to the supply pressure acting on the outer circumferential road half surface 10c of the front pressure surface 10a, and further during this retreat. In the cylinder oil drain passage 1
8, the inner circumferential half surface 10d of the front pressurizing surface 10a is also opened to the rear chamber oiling path 9 in order to communicate the cylinder rear chamber 2b with the rear chamber oiling path 9. By applying the supply oil pressure to the entire surface, the valve 10 increases its retraction speed and retreats at an increased speed to the maximum stroke, and at the same time as the switching of the valve 10 is completed, the piston 3 reaches the retraction end, and then Front pressure surface 3 where supply oil pressure acts
It starts to move forward due to the difference in area between a and the rear pressure surface 3b.

As shown in FIG. 4, when the piston 3 starts to move forward, the second oil passage 20 immediately communicates with the valve oil drain chamber 16, so that the valve oil drain chamber 16 is opened via the second oil passage 20. It communicates with the cylinder rear chamber 2b and its volume decreases as the piston 3 advances, so the oil sucked into the valve oil drain chamber 16 as described above is discharged to the cylinder rear chamber 2b.

After that, the state shown in FIG. 1 is reached, and the same operation as described above is repeated thereafter.

Therefore, the oil passage opening/closing valve 10 supplies oil to the valve 10 at both the forward and backward ends of the piston 3.
By rapidly opening and closing the valve 10, the valve 10 can be quickly switched and the timing at which the piston 3 switches the valve 10 can be delayed, so the effective acceleration distance of the piston 3 increases and the piston 3 In addition to being able to increase the impact force, the valve 10
stroke becomes reliable, the position of the valve 10 after switching is reliably maintained, and the valve 10 performs stable switching operation.

Moreover, as the opening and closing speeds of valves 1 and 0 are further increased during the reciprocating stroke of valve 10, the force applied to valve 10 increases in the latter half of the stroke of valve 10, so that the switching operation of valve 10 is can be performed more stably.

Furthermore, by replenishing the cylinder rear chamber 2b with drained oil from the valve oil drain chamber 16 immediately after the piston 3 starts moving forward, the amount of oil required for switching the valve 10 can be reduced in conjunction with instantaneous switching of the valve 10. (reduced by about 30%), and stable switching operation of the valve 10 can be obtained even by reducing the amount of oil.

As explained above, according to the present invention, it is possible to instantly switch the valve at both the forward and backward ends of the striking piston, and the waste oil of the valve can be used as the piston hydraulic oil. In addition to reducing the amount of oil used, the valve switching operation can be performed stably and reliably by reducing the amount of valve hydraulic fluid used.

[Brief explanation of the drawing]

The drawings illustrate the embodiment of the present invention, and FIG. 1 shows the state of the striking piston at the forward end, FIG. 2 shows the state at the backward end, FIG. 3 shows the state at the backward end, and FIG. The figures are operation explanatory diagrams showing respective states during forward movement. 1... Impact tool body, 2... Cylinder, 2a... Front chamber, 2b... Rear chamber, 3.
...Blow piston, 3a...Front pressure surface, 3b...Rear pressure surface, 3c...Front piston, 3d...Rear Piston, 4...
...Front annular port, 5...Rear annular port,
6...Bit rod, 7...Oil chamber, 8
...Front chamber oil supply passage, 9...Rear chamber oil supply passage, 10...Oil passage opening/closing valve, lea...
... Front pressure surface, 10b ... Rear pressure surface, 10
c...Outer circumference side road half surface, 10d...Inner circumference side road half surface, 11... Valve rear chamber, 12-15.
...Level, 16...Valve oil drain chamber, 17
......First oil path, 18...Cylinder oil drain path, 19...Auxiliary first oil path, 20...
2nd oil passage, 21...accumulator.

Claims (1)

[Scope of utility model registration request] A striking piston is slidably fitted into a cylinder having a front chamber and a rear chamber formed in the striking tool body, and a front annular port is provided on the outer periphery of the piston and communicates with the front chamber of the cylinder near the forward end of the piston. and a rear annular port are arranged in front and back, one end of the front chamber oil supply passage is opened in a part of the front chamber of the cylinder, and one end of the oil supply passage for the front chamber is opened in a part of the rear chamber of the cylinder through an oil passage opening/closing valve. One end of the room oil supply path is opened, and the rear pressure surface of the piston is formed larger than the front pressure surface, and the rear pressure surface of the valve is formed larger than the front pressure surface, and the front pressure surface of the valve is formed larger than the front pressure surface. A portion is always open to the rear chamber oil supply passage, and one end is slightly behind the opening of the front chamber oil supply passage so that one end communicates with the front annular port near the forward end of the piston. The other end of the first oil passage that opens to the piston sliding surface is connected to the other end of the first oil passage, which is opened and closed by the valve, and the other end of the first oil passage that opens to the piston sliding surface is connected to another part of the rear chamber of the cylinder. The outer diameter of the rear piston formed on the rear side of the side annular port is larger than the outer diameter of the front piston formed on the front side of the rear side annular port, and the sliding part of the cylinder on which the rear piston slides. The inner diameter of the cylinder is made to correspond to the outer diameter of the rear piston and larger than the inner diameter of the sliding part of the front piston, and a valve oil drain chamber is formed in the rear annular port by each step of the cylinder and piston. , the other end of the auxiliary first oil passage, which opens at the rear piston sliding surface of the cylinder, is connected to a part of the first oil passage so that one end communicates with the valve oil drain chamber near the retreating end of the piston. death,
A second oil passage that opens at the front piston sliding surface of the cylinder at the valve forward end of the valve sliding surface of the rear chamber of the cylinder so that one end thereof communicates with the valve oil drain chamber immediately after the piston starts moving forward. Open the other end and move the piston forward.
By rapidly supplying and discharging oil to and from the valve rear chamber at both retreating ends, the valve is opened and closed rapidly, and drained oil from the valve oil drain chamber is replenished into the cylinder rear chamber immediately after the piston starts moving forward. A reciprocating switching device for a striking piston in a hydraulic striking tool, characterized in that: