JPS6161946B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hydraulically operated impact tools such as hydraulic breakers and crawler drills.

This type of impact tool uses hydraulic pressure to reciprocate a percussion piston installed in a cylinder of the tool body, and the supply and discharge of pressure oil in the cylinder that reciprocates the percussion piston depends on the reciprocating movement of the piston. It is controlled by an oil passage opening/closing switching valve that operates accordingly.

In conventional impact tools, oil is trapped in an oil chamber formed by the upward switching valve of the switching valve and the piston, and the upward movement of the piston is mechanically performed via the oil cushion.
In addition, since the downward switching of the valve is performed by the action of hydraulic pressure switched by the movement of the piston, the movement of the valve and the movement of the piston are determined mechanically, making it difficult to adjust the timing of the valve and piston. However, there was a problem with follow-up performance, especially when hitting at high speed. Such impact tools therefore have the disadvantage that the desired impact force or number of impacts cannot be achieved.

The present invention aims to eliminate such drawbacks and to provide a hydraulically operated impact tool that is simple in structure, reliable in operation, and adaptable to high-speed impact.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

Referring to FIG. 1, a substantially cylindrical cylinder 1 is provided with a high pressure port 2 and a low pressure port 3 in its upper portion, and is axially formed with a housing portion in which a striking piston 4 slides in the axial direction. The cylinder 1 further has an accumulator 5 in its upper part that communicates with the high pressure port 2,
Further, a striking chamber 6, a hollow chamber 6', a cylinder front chamber 7, a cylinder rear chamber 8, and a step chamber 9 are provided, respectively.

A striking piston 4 that slides back and forth within the cylinder 1
, a front medium diameter portion 10, a front large diameter portion 11, a stepped portion 12, a rear large diameter portion 13, and a rear small diameter portion 14 are sequentially formed, and the front and rear large diameter portions 11 and 13 are respectively formed. Formed with the same diameter. Furthermore, the rear small diameter portion 14
The outer diameter of the front medium diameter portion 10 is smaller than the outer diameter of the front medium diameter portion 10, so that the rear pressurizing surface 15 on the upper surface of the rear large diameter portion 13
is formed larger than the front pressurizing surface 16 on the lower surface of the front large diameter portion 11.

In the front chamber 7 of the cylinder 1, one end of a high pressure passage 17 from the high pressure port 2 opens at a high pressure port 18, and in the rear chamber 8 of the cylinder 1, one end of the high pressure passage 17 from the high pressure port 2 opens at a switching valve 20. The high pressure port 19 opens through the high pressure port 19. In the rear chamber 8 of the cylinder 1, one end of a low pressure passage 25 from the low pressure port 3 is further opened as a low pressure port 26, and the openings of the high pressure port 19 and the low pressure port 26 are opened and closed by the switching valve 20. The low pressure passage 25 further opens into the step chamber 9 formed by the step 12 of the piston at a low pressure port 27.

The cylinder 1 is provided with a pilot passage 29 for the rear chamber 28 of the valve 20 which communicates the rear chamber 28 with the cylinder rear chamber 8 above the flange 21 of the switching valve 20. It has a chamber port 31. The cylinder 1 is further provided with a pilot passage 33 for a valve front chamber that communicates between a valve front chamber 32 (see FIG. 3) formed when the switching valve 20 is raised and the step chamber 9. It has a chamber port 34 and a step chamber port 35.

The switching valve 20 has a substantially annular shape and has a flange portion 21 and a valve port 22 that communicates with a low pressure port 26 . The rear pressurizing surface 23 facing the switching valve rear chamber 28 is formed of an inclined surface and is larger than the front pressing surface 23' facing the switching valve front chamber 32 (see FIG. 4). Switching valve 20
further has a front end surface 24 . The rear pressure surface of the valve is formed wider than the front end surface 24.

A chisel 37 that is struck by the piston 4 is provided at the tip of the cylinder 1 coaxially with the piston 4.

Next, the operation of the hydraulically operated impact tool according to the present invention will be described.

FIG. 1 shows a state in which the piston 4 hits the chisel 37. At this time, the switching valve 20 is in the lower position. Therefore, the high pressure port 19 is closed by the valve 20, and communication between the cylinder rear chamber 8 and the high pressure port 2 side is cut off. Further, the low pressure port 26 communicates with the valve port 22 provided in the valve 20, and the cylinder rear chamber 8 communicates with the low pressure side. On the other hand, the cylinder front chamber 7 has a high pressure port 18 that is always connected to the high pressure port 2.
It communicates with Therefore, the piston 4 starts to rise immediately after hitting the chisel 37 due to the high pressure acting on the front pressure surface 16 of the piston and due to the reaction from hitting the chisel 37. Note that while the piston is rising, the oil in the cylinder rear chamber 8 of the piston is drained from port 2.
2 and 26 to the low pressure side. Incidentally, since the striking chamber 6 and the hollow chamber 6' are always in communication with the atmosphere, the piston 4 can freely move within the cylinder. Since the port 35 of the pilot passage 33 for the valve front chamber 32 communicates with the low pressure port 27 via the stepped portion 12 of the piston, low pressure side pressure acts on the valve front pressure surface 23'. The groove-shaped rear chamber 28 formed at the upper end of the inner wall of the cylinder hollow part of the valve rear pressure surface 23 is connected to the cylinder of the piston rear pressure surface 15 through the cylinder rear chamber port 31 of the pilot passage 29 and the port 36 of the rear chamber 28. Since it communicates with the rear chamber 8, the pressure of the rear chamber 8 of the piston rear pressure surface 15 acts on the valve rear pressure surface 23. Valve front end surface 2
4 is always at the same pressure as the cylinder rear chamber 8, so the pressure of the cylinder rear chamber 8 acts on the valve front end surface 24 as well as the valve rear pressurizing surface 23. The pressure in the cylinder rear chamber 8 becomes slightly higher than the pressure on the low pressure side due to the throttling effect of the low pressure port 26 or the valve port 22 while the piston is rising. Therefore, if the vertical forces acting on the rear pressure surface 23, front end surface 24, and front pressure surface 23' of the valve are respectively X, Y, and Z, then
>Y+Z, and the valve is on the rear pressure surface 23 of the valve.
The cylinder is held in the lower (front) position by the pressure in the rear chamber of the cylinder. In this way, the piston 4 moves to the position shown in FIG.

When the piston 4 rises and the port 31 of the pilot passage 29 communicates with the low pressure port 27 via the stepped portion 12 of the raised piston, pressure on the low pressure side acts on the pressure surface 23 on the rear side of the valve. However, at this time, the stepped chamber port 35 of the pilot passage 33 is closed by the front large diameter portion 11 of the piston 4, so the pilot passage 33 is closed. Valve 20 is thus held in the lower (forward) position.

Referring to FIG. 2, where the piston starts to rise, and FIG. 3, which shows the limit of the rise, when the high pressure port 18 communicates with the step chamber port 35 in the figure, high pressure side pressure acts on the valve front pressurizing surface 23'. do.
At this time, since the port 31 of the pilot passage 29 communicates with the low pressure port 27 via the stepped portion 12 of the piston, pressure on the low pressure side is acting on the pressure surface 23 on the rear side of the valve. Therefore, the above-mentioned vertical force becomes X<Y+Z, and the valve starts to rise due to the high pressure acting on the valve front pressurizing surface 23'. Note that while the piston 4 is rising, oil on the high pressure side is stored in the accumulator 5.

Next, a description will be given with reference to FIG. 3, which shows a state in which the piston has begun to descend, to FIG. 4, which shows a state near the lowering limit.

When the valve 20 rises, communication between the valve port 22 and the low pressure port 26 is cut off, and thus communication between the cylinder rear chamber 8 and the low pressure side is cut off. At the same time, the high pressure port 19 communicates with the cylinder rear chamber 8, and the cylinder rear chamber 8 communicates with the high pressure side. Therefore, the oil on the high pressure side and the oil stored in the accumulator flow into the cylinder rear chamber through the port 19. The port 31 of the pilot passage 29 is connected to the stepped portion 1 of the piston.
2 to the low-pressure port 27, the pressure on the low-pressure side acts on the rear pressure surface 23 of the valve. Since the port 35 of the pilot passage 33 communicates with the high pressure port 18, high pressure side pressure acts on the valve front pressure surface 23'.
On the other hand, the pressure of the cylinder rear chamber 8 (pressure on the high pressure side) acts on the valve front end surface 24. For this reason,
The vertical force explained with reference to Figure 1 is X<Y
+Z, and the valve is held in the upper (rear) position by the high pressure acting on the valve front pressurizing surface 23' and the front end surface 24. Therefore, since the piston rear pressure surface 15>the piston front pressure surface 16, when the cylinder rear chamber 8 communicates with the high pressure side, the piston stops rising, reverses, and starts descending.

The piston descends, and the step chamber port 35 of the valve front chamber pilot passage 33 connects to the step 12 of the piston.
When the valve is communicated with the low pressure port 27 through the valve, low pressure side pressure acts on the valve front pressurizing surface 23'. However, the port 31 of the cylinder rear chamber 8 of the pilot passage 29 is blocked by the rear large diameter portion 13 of the piston, and the pilot passage 29 is closed. Further, high pressure is acting on the valve front end surface 24. Therefore, the valve is held in the upper (rearward) position.

Finally, the explanation will be given with reference to FIG. 4, which shows the state immediately before the piston 4 descends and the chisel 37 starts striking.

When the piston descends and the port 31 of the pilot passage 29 communicates with the rear cylinder chamber 8, high pressure acts on the pressure surface 23 on the rear side of the valve. On the other hand, since the port 35 of the pilot passage 33 communicates with the low pressure port 27 via the stepped portion 12 of the piston, low pressure side pressure acts on the valve front pressure surface 23'. For this reason, even if the front end face of the valve
Even if the high pressure in the cylinder rear chamber 8 acts on the valve 4, the above-mentioned vertical force becomes X>Y+Z, and the valve is lowered by the high pressure acting on the valve rear pressurizing surface 23.

When the valve is lowered, the high pressure port 19 is closed, and communication between the cylinder rear chamber 8 and the high pressure side is cut off. At the same time, the low pressure port 26 and the valve port 22
The cylinder rear chamber 8 communicates with the low pressure side.
Since the cylinder front chamber 7 is always in communication with the high pressure port 18, the piston rises again due to the high pressure acting on the front pressurizing surface 16 and the reaction from hitting the chisel, and repeats the operation cycle shown in FIGS. 1 to 4. repeat.

As described in detail above, the present invention includes a piston having a stepped portion that is slidable in the axial direction in a hollow part within a cylinder, and a switching valve that is slidable on the inner wall of the hollow part in the cylinder at the upper part of the piston. , a hydraulically operated impact tool having a hollow part of the cylinder divided into a front chamber and a rear chamber via a stepped part of the piston, and having high pressure and low pressure passages in the cylinder, wherein the high pressure passage is connected to the front chamber of the cylinder. The low-pressure passage is connected to the rear chamber through a high-pressure port opened to the front chamber and opened and closed by the sliding of a switching valve having a flange, and the low-pressure passage is connected to the rear chamber by a piston step interposed between the front chamber and the rear chamber. A valve rear chamber and a cylinder are opened into the step chamber formed and communicated with the rear chamber through ports formed in the slidable switching valve, and are formed above the flange portion of the switching valve. The rear chamber is communicated with one pilot passage, and the valve front chamber formed below the flange of the switching valve and the step chamber are communicated with another pilot passage. In the vicinity, the first pilot passage is communicated with the low pressure passage through a step chamber, and the other pilot passage is communicated with the high pressure passage, and in the vicinity of the forward end of the piston, the first pilot passage is communicated with the high pressure passage. Moreover, due to the extremely compact structure in which the other pilot passage is provided to communicate with the low pressure passage through the step chamber, the piston and the valve can be freely arranged within the cylinder without mechanically interlocking them,
The valves can be switched reliably and quickly by causing both to operate in relation to each other using hydraulic pressure, and the valve can be held securely after switching, so it can be used in hydraulic breakers or crawler drills, etc., and can be used at high speeds with unprecedented reliability. This allows for repeated strikes.

Further, near the forward end of the piston, the one pilot passage is communicated with the cylinder rear chamber and the one pilot passage is communicated with the high pressure passage, so that the oil in the cylinder rear chamber can be used for switching the valve without wasting it. Can be, practically
This has great economic effects.

[Brief explanation of the drawing]

FIG. 1 is a central vertical cross-sectional view showing the striking position of the hydraulically operated impact tool according to the present invention, and FIGS. 2 to 4 are central vertical cross-sectional views of each stroke from the backward stroke to the forward stroke of the tool shown in FIG. are shown respectively. 1...Cylinder, 2...High pressure port, 3...Low pressure port, 4...
Impact piston, 5...Accumulator, 7...Cylinder front chamber, 8...Cylinder rear chamber, 10...Front middle diameter part,
DESCRIPTION OF SYMBOLS 11... Front large diameter part, 12... Step part, 13... Rear large diameter part, 14... Rear small diameter part, 15... Rear pressure surface of piston, 16... Front pressure surface of piston, 17... High pressure passage, 18, 19...High pressure port, 20...Switching valve, 21...Flange part, 22...Valve port, 2
3... Rear pressurizing chamber surface of valve, 23'... Front pressurizing surface of valve, 24... Front end surface of valve, 25... Low pressure passage, 26, 27... Low pressure port, 28... Rear chamber of valve, 29, 33... Pilot passage, 30, 31,
34, 35, 36...port, 37...chisel.

Claims (1)

[Scope of Claims] 1. A piston having a stepped portion that is slidable in the axial direction in a hollow part within the cylinder, and a switching valve that is slidable on the inner wall of the hollow part in the cylinder at the upper part of the piston, A hydraulically operated impact tool having a hollow portion divided into a front chamber and a rear chamber via a stepped portion of the piston, and having high pressure and low pressure passages in the cylinder, the high pressure passage opening into the front chamber of the cylinder. , and communicate with the rear chamber through high-pressure ports that are opened and closed by sliding of a switching valve having a flange portion, and the low-pressure passage is formed by a piston stage interposed between the front chamber and the rear chamber. A valve rear chamber and a cylinder rear chamber are formed above the flange portion of the switching valve, and are opened in the step chamber and communicated with the rear chamber through ports formed in the slidable switching valve. communicate through one pilot passage, and communicate a valve rear chamber formed below the flange of the switching valve with the step chamber through another pilot passage, near the retreating end of the piston, The first pilot passage communicates with a low pressure passage through a step chamber, and the other pilot passage communicates with a high pressure passage, and near the forward end of the piston, the first pilot passage communicates with the high pressure passage, and A hydraulically operated impact tool characterized in that the other pilot passage is communicated with a low pressure passage via a step chamber. 2. The hydraulically operated impact tool according to claim 1, wherein the piston has a front medium diameter section, a front large diameter section, a stepped section, a rear large diameter section, and a rear small diameter section sequentially formed on the outer circumference. 3. The stepped chamber of the piston comprises a space of a front stepped portion formed by the front large diameter portion and the rear large diameter portion in close contact with the inner wall of the hollow portion. Hydraulically operated impact tool. 4. Claims in which the rear pressure surface of the rear large diameter portion formed on the rear chamber side is formed wider than the front pressure surface of the front large diameter portion formed on the front chamber side. Hydraulically operated impact tool according to item 2. 5. The hydraulically operated impact tool according to claim 1, 2 or 4, wherein the flange portion of the switching valve has an upper surface wider than a lower surface thereof. 6. Claims 1, 2, and 4, wherein the flange portion of the switching valve is slidably provided in a groove-shaped valve rear chamber formed in the upper end of the inner wall of the hollow portion of the cylinder. or the hydraulically operated impact tool according to item 5. 7. The lower surface of the flange portion is engaged with a port of a valve front chamber formed at the upper opening end of the other pilot passage, and is slidably provided in the valve front chamber and the valve rear chamber. A hydraulically operated impact tool according to scope 6. 8. The hydraulically operated impact tool according to claim 5, 6 or 7, wherein the upper surface of the flange portion of the switching valve is formed wider than the front end surface corresponding to the lower surface of the switching valve.