Hydraulic impact device

Abstract

To provide a hydraulic striking device that is able to suppress a surge of a low-pressure circuit during backward movement of a piston while enabling sufficient supply of pressure oil when striking the piston.SOLUTION: A hydraulic breaker 10 that strikes a striking rod by moving a piston 15 forward and backward in a cylinder 11 by supplying pressure oil to a high-pressure circuit 124 by means of a hydraulic pump P and discharging the pressure oil from a low-pressure circuit 127 to a tank T, includes: a first control valve 30 as a switching valve mechanism that is disposed non-coaxially with an axis of the piston 15 and controls forward and backward movement strokes of the piston 15; and a switching accumulator 21 that is connected to the high-pressure circuit 124 and separated from the low-pressure circuit 127 during a forward movement stroke of the piston 15 and connected to the low-pressure circuit 127 and separated from the high-pressure circuit 124 during a backward movement stroke of the piston 15.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydraulic impact device such as a rock drill or a hydraulic breaker. [Background technology]

[0002] As a hydraulic impact device of this type, for example, the technology described in Patent Document 1 is disclosed. As shown in the schematic diagram of FIG. 11, the hydraulic impact device described in the document includes a cylinder 11, a piston 15 slidably fitted inside the cylinder 11, a front piston chamber 11a and a rear piston chamber 11b defined between the outer peripheral surface of the piston 15 and the inner peripheral surface of the cylinder 11 and spaced apart from each other in the axial direction, a switching valve mechanism 130 that switches at least one of the front piston chamber 11a and the rear piston chamber 11b to at least one of a high-pressure circuit 124 and a low-pressure circuit 127 to drive the piston 15, a low-pressure accumulator 121 provided in the low-pressure circuit 127, and a high-pressure accumulator 122 provided in the high-pressure circuit.

[0003] The hydraulic impact device described in the document supplies pressure oil to a high-pressure circuit 124 by a hydraulic pump P and discharges the pressure oil from a low-pressure circuit 127 to a tank T, thereby moving the piston 15 back and forth within the cylinder 11 and striking the striking rod. The hydraulic impact device described in the document is an example of a front / rear chamber switching type (front / rear chamber high / low pressure switching). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-042865 A (paragraph 0009) Summary of the Invention [Problem to be solved by the invention]

[0005] The high-pressure accumulator compensates for the shortage of oil discharged from the hydraulic pump when the piston moves forward. The larger the capacity of the high-pressure accumulator, the more oil can be supplied. This reduces the pressure drop in the hydraulic circuit, and the force of the piston striking the rear end of the rod is effectively converted into kinetic energy, resulting in high impact energy.

[0006] Meanwhile, the repulsive force of the piston striking the rear end of the rod causes high pressure fluctuations in the piston rear chamber. If this pressure fluctuation spreads to the oil return line during the piston's retraction stroke, it can cause vibrations in the return hose and affect the life of the rear seal. In response to this, a low-pressure accumulator installed midway through the low-pressure circuit buffers the pulsation of oil in the low-pressure circuit, suppressing surges in the low-pressure circuit during the piston's retraction stroke. However, there is a limit to the size of a practical accumulator that can be mounted, and therefore there is still room for improvement in providing a small and compact hydraulic impact device that satisfies the required functions of enabling a sufficient supply of pressurized oil when the piston strikes during its forward stroke and suppressing surges in the low-pressure circuit during the piston's retraction stroke.

[0007] Therefore, the present invention has been made with an eye on such problems, and its object is to provide a small and compact hydraulic impact device that can supply sufficient pressurized oil during the forward stroke of the piston while suppressing surges in the low-pressure circuit during the backward stroke of the piston. [Means for solving the problem]

[0008] In order to solve the above problems, a hydraulic impact device according to a first aspect of the present invention is a hydraulic impact device that uses a hydraulic pump to supply pressurized oil to a high-pressure circuit and discharge pressurized oil from a low-pressure circuit to a tank, thereby moving a piston back and forth within a cylinder to impact a striking rod, and is characterized by having a switching accumulator that is connected to the high-pressure circuit and disconnected from the low-pressure circuit during the forward stroke of the piston, and that is connected to the low-pressure circuit and disconnected from the high-pressure circuit during the backward stroke of the piston.

[0009] The switching accumulator of the hydraulic impact device according to the first aspect is connected to high pressure during the forward stroke and to low pressure during the reverse stroke, thereby supplying pressure oil to the hydraulic circuit during the impact phase when energy replenishment is required, and buffering surge pressure when the piston retracts, preventing or suppressing damage to equipment. In other words, according to the hydraulic impact device of the first aspect of the present invention, the switching accumulator is connected to the low-pressure circuit and disconnected from the high-pressure circuit during the piston's retraction stroke, thereby cushioning the pulsation of pressurized oil in the low-pressure circuit and suppressing low-pressure surges.

[0010] The switching accumulator is connected to the high-pressure circuit and disconnected from the low-pressure circuit during the forward stroke of the piston, allowing a larger amount of pressurized oil to be supplied during the forward stroke of the piston. This reduces the pressure drop in the hydraulic circuit and effectively converts the impact force of the piston during the forward stroke into kinetic energy, thereby obtaining a large amount of impact energy. Thus, according to the hydraulic impact device of the first aspect of the present invention, by switching the connection state of one switching accumulator between the high-pressure circuit and the low-pressure circuit at appropriate operating timing, it is possible to combine the functions of an accumulator for the high-pressure circuit and an accumulator for the low-pressure circuit, thereby achieving a small and compact configuration while satisfying the required functions described above. Note that the hydraulic impact device of the first aspect is applicable to "rear chamber switching type" and "front and rear chamber switching type" hydraulic impact devices (for example, see the configuration examples of Figures 8 and 10 in the embodiment).

[0011] In order to solve the above problems, a hydraulic impact device according to a second aspect of the present invention is a hydraulic impact device that uses a hydraulic pump to supply pressurized oil to a high-pressure circuit and discharges pressurized oil from a low-pressure circuit to a tank, thereby moving a piston back and forth within a cylinder to impact a striking rod, and is characterized by having a switching accumulator that switches from being connected to one of the high-pressure circuit and the low-pressure circuit to being connected to the other when the piston transitions from either a forward stroke or a reverse stroke to the other.

[0012] The switching accumulator of the hydraulic impact device according to the second aspect can function as both an accumulator for the high-pressure circuit and an accumulator for the low-pressure circuit by switching the connection state of a single switching accumulator between the high-pressure circuit and the low-pressure circuit at appropriate operational timing during the impact cycle, regardless of the operating state (forward / reverse) of the piston. In other words, even with the switching accumulator of the second aspect, pressurized oil is supplied into the circuit when connected at high pressure, and surge pressure is buffered when connected at low pressure, thereby suppressing damage to equipment. Therefore, it is possible to achieve a small and compact configuration while satisfying the required functions described above. Note that the hydraulic impact device according to the second aspect is not limited in terms of the operating state (forward / reverse) of the piston, and therefore all hydraulic impact devices of the "rear chamber switching type," "front chamber switching type," and "front and rear chamber switching type" are applicable (see, for example, the configuration examples in Figures 8, 9, and 10 in the embodiments).

[0013] In order to solve the above problems, a hydraulic impact device according to a third aspect of the present invention is a hydraulic impact device that uses a hydraulic pump to supply pressure oil to a high-pressure circuit and discharge pressure oil from a low-pressure circuit to a tank, thereby moving a piston back and forth within a cylinder to impact a striking rod, and that includes a piston front chamber and a piston rear chamber that are defined between an outer peripheral surface of the piston and an inner peripheral surface of the cylinder and are spaced apart from each other in the axial direction, a switching valve mechanism that switches at least one of the piston front chamber and the piston rear chamber to at least one of the high-pressure circuit and the low-pressure circuit to drive the piston, and a hydraulic circuit that supplies or discharges pressure oil to either the piston front chamber or the piston rear chamber. and a second accumulator interposed in a hydraulic circuit that supplies or discharges pressurized oil to the other of the front piston chamber and the rear piston chamber, wherein the switching accumulator switches from being connected to one of the high pressure circuit and the low pressure circuit to being connected to the other when the piston transitions from either a forward stroke or a reverse stroke to the other, and the second accumulator is in a connection state opposite to that of the switching accumulator when the piston transitions from either a forward stroke or a reverse stroke to the other.

[0014] According to the hydraulic impact device of the third aspect, regardless of the operating state (forward / reverse) of the piston, the connection state of the two accumulators can be switched between the high-pressure circuit and the low-pressure circuit at appropriate operating timing during the impact cycle, thereby enabling the device to function as both an accumulator for the high-pressure circuit and an accumulator for the low-pressure circuit. That is, in the third embodiment, the switching accumulator is switchably connected to high pressure / low pressure during an impact cycle, and the second accumulator is connected in the opposite manner to the switching accumulator. As a result, the switching accumulator supplies pressure oil to the circuit when connected to high pressure, and buffers surge pressure when connected to low pressure to prevent damage to equipment, and the second accumulator can complement the function of the switching accumulator. Therefore, it is possible to achieve a small and compact configuration while satisfying the above-mentioned required functions. Note that the hydraulic impact device according to the third aspect is not limited in terms of the operating state (forward / reverse) of the piston, and therefore all hydraulic impact devices of the "rear chamber switching type," "front chamber switching type," and "front and rear chamber switching type" are applicable (see, for example, the configuration examples in Figures 5, 6, and 7 in the embodiments).

[0015] In order to solve the above problems, a hydraulic impact device according to a fourth aspect of the present invention is a hydraulic impact device that uses a hydraulic pump to supply pressure oil to a high-pressure circuit and discharge pressure oil from a low-pressure circuit to a tank, thereby moving a piston back and forth within a cylinder to impact a striking rod, and includes a piston front chamber and a piston rear chamber that are defined between an outer peripheral surface of the piston and an inner peripheral surface of the cylinder and are spaced apart from each other in the axial direction, a switching valve mechanism that switches at least one of the piston front chamber and the piston rear chamber to at least one of the high-pressure circuit and the low-pressure circuit to drive the piston, and The hydraulic pressure control device includes a switching accumulator interposed in a hydraulic circuit that supplies or discharges pressurized oil to either one of a front chamber or the piston rear chamber, and a second accumulator interposed in a hydraulic circuit that supplies or discharges pressurized oil to the other of the piston front chamber or the piston rear chamber, wherein the switching accumulator switches from being connected to either one of the high-pressure circuit or the low-pressure circuit to being connected to the other when the piston transitions from either a forward stroke or a reverse stroke to the other, and the second accumulator is always connected to the high-pressure circuit.

[0016] The switching accumulator of the hydraulic impact device according to the fourth aspect combines the functions of an accumulator for the high-pressure circuit and an accumulator for the low-pressure circuit by switching the connection state of the switching accumulator between the high-pressure circuit and the low-pressure circuit at appropriate operating timing during the impact cycle, regardless of the operating state (forward / reverse) of the piston, while the second accumulator is always connected at high pressure. By using the second accumulator exclusively for high pressure, the second accumulator essentially functions as a main accumulator, and the switching accumulator complements the function of the second accumulator. Although the hydraulic impact device according to the fourth aspect is not limited in terms of the operating state (forward / reverse) of the piston, the second accumulator is exclusively for high pressure. Therefore, the hydraulic impact device according to the fourth aspect is applicable to "rear chamber switching type" and "front chamber switching type" hydraulic impact devices (see, for example, the configuration examples of Figures 5 and 6 in the embodiments).

[0017] Here, in a hydraulic impact device according to any one of the aspects of the present invention, there are provided a front-piston chamber and a rear-piston chamber defined between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder and spaced apart from each other in the axial direction, a switching valve mechanism that switches at least one of the front-piston chamber and the rear-piston chamber to at least one of the high-pressure circuit and the low-pressure circuit to drive the piston, and an accumulator control valve that switches its own oil path in response to a change in the connection state of the front-piston chamber or the rear-piston chamber with the high-pressure circuit or the low-pressure circuit as a pilot signal, and it is preferable that the switching accumulator is configured so that its connection state is switched between the high-pressure circuit and the low-pressure circuit via the accumulator control valve. [Effects of the Invention]

[0018] As described above, according to the present invention, with a small and compact configuration, it is possible to supply sufficient pressure oil during the forward stroke of the piston, while suppressing surges in the low-pressure circuit during the retraction stroke of the piston. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic longitudinal cross-sectional view, including a block diagram, showing an example of the configuration of a rear chamber switching hydraulic breaker in a first embodiment of a hydraulic impact device according to one aspect of the present invention, showing the state of the piston's forward stroke. [Figure 2]2A and 2B are explanatory diagrams of an example of mounting the hydraulic breaker in FIG. 1, in which FIG. 2A shows a plan view and FIG. 2B shows a cross section along the axis as viewed from the front. [Figure 3] 2 is an enlarged view of the control valve portion in FIG. 1, in which FIG. 2(a) shows the first control valve and FIG. 2(b) shows the second control valve. [Figure 4] FIG. 1 is a schematic longitudinal cross-sectional view, including a block diagram, showing an example of the configuration of a hydraulic breaker in a first embodiment of a hydraulic impact device according to one aspect of the present invention, in which the piston is transitioning from a forward stroke to a reverse stroke. [Figure 5] 1A and 1B are schematic diagrams illustrating a first embodiment of a hydraulic impact device (rear chamber switching type + two accumulators) according to one aspect of the present invention, in which (a) shows the state of the piston in the forward stroke, and (b) shows the state of the piston moving from the forward stroke to the reverse stroke. The hatched cylinder indicates a high-pressure connection (the same applies to the following schematic diagrams of other embodiments and conventional examples). [Figure 6] 10A and 10B are schematic diagrams illustrating a second embodiment (switchable front chamber + two accumulators) of a hydraulic impact device according to one aspect of the present invention. [Figure 7] 10A and 10B are schematic diagrams illustrating a third embodiment (front and rear chamber switching type + two accumulators) of a hydraulic impact device according to one aspect of the present invention. [Figure 8] 10A and 10B are schematic diagrams illustrating a fourth embodiment (rear chamber switching type+one accumulator) of a hydraulic impact device according to an aspect of the present invention. [Figure 9] 10A and 10B are schematic diagrams illustrating a fifth embodiment (front chamber switching type+one accumulator) of a hydraulic impact device according to one aspect of the present invention. [Figure 10] 10A and 10B are schematic diagrams illustrating a sixth embodiment (front and rear chamber switching type + one accumulator) of a hydraulic impact device according to an aspect of the present invention. [Figure 11] 1A and 1B are schematic diagrams illustrating an example of a conventional hydraulic impact device (front and rear chamber switching type + two accumulators). DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationships and ratios between thicknesses and planar dimensions may differ from the actual ones, and the relationships and ratios of dimensions may differ between the drawings. Furthermore, the embodiments described below are intended to exemplify devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to the embodiments described below.

[0021] [First embodiment] In the first embodiment, a hydraulic breaker of a rear chamber switching type (front chamber always connected to high pressure-rear chamber high / low pressure switching) will be described as an example of a hydraulic impact device according to the present invention. 1, a hydraulic breaker 10 of the first embodiment includes a cylindrical piston 15 and a cylinder 11 into which the piston 15 slides. The piston 15 slides in the cylinder 11 via a cylinder liner 16 at the front of the cylinder 11 and a seal retainer 17 at the rear of the cylinder 11, allowing the piston 15 to move forward and backward in the axial direction. A front piston chamber 11a and a rear piston chamber 11b are defined between the outer peripheral surface of the piston 15 and the inner peripheral surface of the cylinder 11, and are spaced apart from each other in the axial direction. In the rear chamber switching type, the front piston chamber 11a shown in Figure 1 is constantly connected to the high-pressure circuit 124. A back head 13, which defines a gas chamber therein, is attached to the rear end of the cylinder 11.

[0022] A front head 12 is coaxially attached to the front of the cylinder 11, and a chisel 14 is supported coaxially with a piston 15 on the front head 12 via a front cover 18 at the front of the axial direction and a front holder 19 at the rear. The front head 12, cylinder 11, and back head 13 are integrally connected by a through bolt 20 inserted from the rear end of the back head 13. As shown in Fig. 2, a switching accumulator 21, a first control valve 30, and a second accumulator 22 are provided on the same side of the side of the cylinder 11, in that order from the rear. The axis CL1 of the first control valve 30 (see Fig. 3) is disposed on the side of the cylinder 11 non-coaxially with the piston 15. Note that the operating mechanisms of the impact device and individual components in the hydraulic breaker 10 of this embodiment are basically known, and therefore will not be described in detail.

[0023] 3(a), the first control valve 30 of this embodiment has a rectangular parallelepiped valve housing 101 fixed to the side of the cylinder 11. Inside the valve housing 101, a valve chamber space 105 is defined by a cylindrical through-hole that penetrates in the axial direction and has a multi-stage inner diameter. The sides of the valve chamber space 105 are connected in appropriate positions so that the high pressure circuit 124 and low pressure circuit 127, as well as the valve control passage 125, the rear chamber passage 126, and the accumulator switching passage 128 communicate with the valve chamber space 105.

[0024] The first control valve 30 is formed as a valve retainer fitting portion having a large-diameter opening at the rear (right side in the figure) of the valve chamber space 105, and a small-diameter opening at the front (left side in the figure) of the valve chamber space 105, with a plug 113 screwed onto its end to close it. The valve retainer 102 and valve 106 are housed coaxially within this closed space. A cover 111 is attached to the opening of the valve retainer fitting portion with bolts 112 to close it. The valve 106, which is slidably fitted inside the valve retainer 102, has a hollow cylindrical shape and, from front to rear, has a medium diameter section 107, a large diameter section 108, and a small diameter section 109. A communicating groove 110 is formed on the outer diameter side in the middle of the small diameter section 109.

[0025] The valve chamber space 105 is constantly connected to a high pressure via the high-pressure circuit 124. As a result, the valve 106 of the first control valve 30 is urged rearward by the difference in pressure-receiving area between the medium diameter portion 107 and the small diameter portion 109, and comes into contact with the end face of the valve retainer 102, stopping at the rear end position. In this state, the drain chamber 115 and the low-pressure communication chamber 116 are connected by the communication groove 110, so that the rear chamber passage 126 is connected to the low-pressure circuit 127, and the piston rear chamber 11b shown in FIG.

[0026] On the other hand, when high-pressure oil is supplied from the valve control passage 125 to the valve control chamber 114, the pressure-receiving area behind the large diameter portion 108 is increased, and as a result, the valve 106 is urged forward and stops at the front end position of the valve chamber space 105. In this state, communication between the drain chamber 115 and the low-pressure communication chamber 116 is blocked, and the high-pressure communication chamber 117 is connected to the valve chamber space 105. Therefore, the rear chamber passage 126 is connected to the high-pressure circuit 124, and the piston rear chamber 11b shown in FIG. 1 is connected to the high-pressure circuit 124. In this way, when the piston rear chamber 11b is connected to low pressure, the piston 15 moves backward, and when the piston rear chamber 11b is connected to high pressure, the piston 15 moves forward. In this way, the oil path is switched by the first control valve 30 in accordance with the forward / reverse stroke of the valve 106, and the forward / reverse stroke of the piston 15 is controlled by the supply and discharge of pressure oil for moving the piston 15 forward and backward.

[0027] In this embodiment, as shown in FIG. 1, the cylinder 11 is provided with a stroke adjustment passage 123 between the valve control passage 125 and the high-pressure circuit 124, and a manual stroke adjustment valve 50 is attached to an appropriate position on the side of the cylinder 11. In this embodiment, the stroke adjustment valve 50 switches the flow path from the valve control passage 125 to the stroke adjustment passage 123, thereby changing the timing at which the piston 15 switches from the retraction stroke to the forward stroke, thereby changing the impact cycle from a long stroke to a short stroke. In this way, the stroke adjustment valve 50 functions as a well-known stroke adjustment mechanism.

[0028] 1, the hydraulic breaker 10 of this embodiment further includes a second control valve 40 for controlling the switching accumulator 21. The second control valve 40 functions as an accumulator control valve that switches its own oil path using a change in the connection state between the piston rear chamber 11b and the high-pressure circuit 124 or the low-pressure circuit 127 as a pilot signal. 2, the second control valve 40 of this embodiment is located between the first control valve 30 and the switching accumulator 21 and is built into the thick portion on the front side of the back head 13. The axis CL2 of the second control valve 40 (see FIG. 3) is not coaxial with the piston 15 and the first control valve 30 and is disposed along a direction perpendicular to them.

[0029] As shown in FIG. 3(b), the second control valve 40 of this embodiment includes a valve retainer 201 that is fitted into a mounting hole formed in the thick portion at the front of the back head 13, and a hollow cylindrical switching valve 206 that is fitted into the valve retainer 201. The valve chamber space of the valve retainer 201 is formed by a cylindrical through-hole with a multi-stage inner diameter, one axial end of which is connected to the high-pressure circuit 124 and the other end of which is closed. When the piston rear chamber 11b and the accumulator connecting passage 128 are under high pressure, the switching valve 206 moves to the left as shown in the lower part of FIG. 3(b) due to the difference in pressure-receiving area, and when the piston rear chamber 11b and the accumulator connecting passage 128 are under low pressure, the switching valve 206 moves to the right as shown in the upper part of FIG. 3(b).

[0030] More specifically, in the second control valve 40, a valve retainer 201 and a switching valve 206 are coaxially housed in a valve chamber space 205. In this embodiment, the valve retainer 201 is made up of a pair of hollow cylindrical valve retainers 202A and 202B in order to simplify the processing of the back head 13, and the valve retainers 202A and 202B guide the switching valve 206 inside the back head 13. The switching valve 206 has a hollow cylindrical shape and has, from the front to the rear, a medium diameter section 207, a large diameter section 208, and a small diameter section 209. A communication groove 210 is formed on the outer diameter side of the middle of the small diameter section 209.

[0031] The valve chamber space 205 is constantly connected to a high pressure via the high-pressure circuit 124. As a result, as shown in the upper part of FIG. 1(b), when low-pressure oil in the piston rear chamber 11b is supplied from the accumulator switching passage 128 to the valve control chamber 214, the switching valve 206 of the second control valve 40 is urged rearward by the difference in pressure-receiving area between the medium diameter portion 207 and the small diameter portion 209, and comes into contact with the end face of the valve retainer 201 (202A in this example), stopping at the rear end position. In this state, the drain chamber 215 and the low-pressure communication chamber 216 communicate with each other through the communication groove 210 , so that the low-pressure communication chamber 216 is connected to the low-pressure circuit 127 , and the switching accumulator 21 is connected to the low-pressure circuit 127 .

[0032] On the other hand, when high-pressure oil in the piston rear chamber 11b is supplied from the accumulator switching passage 128 to the valve control chamber 214, the pressure-receiving area behind the large diameter portion 208 is added, and as a result, as shown in the lower part of FIG. 1(b), the switching valve 206 is urged forward and stops at the front end position of the valve retainer 201 (202B in this example) in the valve chamber space 205. In this state, the communication between the drain chamber 215 and the low-pressure communication chamber 216 is blocked, and the high-pressure communication chamber 217 is connected to the valve chamber space 205. Therefore, the high-pressure communication chamber 217 is connected to the high-pressure circuit 124, and the switching accumulator 21 is connected to the high-pressure circuit 124.

[0033] As a result, during the backward stroke of the piston 15, as described above, the piston rear chamber 11b becomes low pressure, and the switching valve 206 of the second control valve 40 is switched by the pilot pressure of the accumulator switching passage 128 that communicates with the piston rear chamber 11b, so that the connection state of the switching accumulator 21 is switched between the high-pressure circuit 124 and the low-pressure circuit 127 via the second control valve 40. That is, when the piston 15 moves forward, the pilot pressure in the accumulator switching passage 128 becomes high. As a result, the switching valve 206 of the second control valve 40 moves to the left, as shown in the lower part of Figure 3(b) , and as a result, when the piston 15 moves forward, the switching accumulator 21 is connected to the high-pressure circuit 124 and disconnected from the low-pressure circuit 127, as shown in Figures 1 and 5(a) .

[0034] Furthermore, during the retraction stroke of the piston 15, the pilot pressure in the accumulator switching passage 128 becomes low. As a result, the switching valve 206 of the second control valve 40 moves to the right, as shown in the upper part of Figure 3(b) in the same figure, and as a result, during the retraction stroke of the piston 15, the switching accumulator 21 is connected to the low-pressure circuit 127 and disconnected from the high-pressure circuit 124, as shown in Figures 4 and 5(b).

[0035] Next, the operation and effects of the hydraulic breaker 10 of the first embodiment will be described. According to the hydraulic breaker 10 of this embodiment, as described above, during the backward stroke of the piston 15, the piston rear chamber 11b becomes low pressure, and the switching valve of the second control valve 40 is switched by the pilot pressure of the accumulator switching passage 128, and in response, the switching accumulator 21 is connected to the low-pressure circuit 127 and functions as an accumulator for the low-pressure circuit. In other words, when the piston 15 moves backward after striking (when the pressure in the piston rear chamber 11b is low or the switching pressure of the first control valve 30 is low), the switching valve 206 of the second control valve 40 receives the corresponding pilot pressure in the accumulator switching passage 128 and switches. As a result, the switching accumulator 21 is connected to the low-pressure circuit 127 and performs a buffering and damping function as an accumulator for the low-pressure circuit, buffering the pulsation of the pressure oil in the low-pressure circuit 127 and, in particular, buffering pressure peaks exceeding the enclosed gas pressure (for example, 6 MPa) to suppress low-pressure surges.

[0036] According to the hydraulic breaker 10 of this embodiment, when the piston 15 moves forward (the pressure in the piston rear chamber 11b is high or the switching pressure of the first control valve 30 is high), the switching valve 206 of the second control valve 40 receives the corresponding pilot pressure in the accumulator switching passage 128 and switches. As a result, the switching accumulator 21 is connected to the high-pressure circuit 124, and in cooperation with the second accumulator 22, which is a high-pressure accumulator, it functions as a high-pressure accumulator (replenishes oil and attenuates high-pressure pressure peaks), thereby attenuating peaks of pressure fluctuations in the piston rear chamber.

[0037] In other words, when the piston 15 moves forward, the piston rear chamber 11b becomes high pressure, and the switching valve 206 of the second control valve 40 is switched by the pilot pressure of the accumulator switching passage 128, and in response, the switching accumulator 21 functions as an auxiliary accumulator for the high-pressure accumulator. This allows a larger amount of pressure oil to be supplied during the forward stroke, reducing the pressure drop in the circuit, and the force of the impact on the piston 15 during the forward stroke is effectively converted into kinetic energy, resulting in high impact energy.

[0038] As described above, the hydraulic breaker 10 of the first embodiment can suppress low-pressure surges during the retraction stroke of the piston while supplying sufficient pressure oil during the advance stroke in which the piston advances. The hydraulic impact device according to the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. For example, the switching accumulator 21 in the first embodiment described above may be configured to switch the connection state between the high-pressure circuit 124 and the low-pressure circuit 127. In other words, it is only necessary that the switching accumulator 21 be able to switch the oil path to which it is connected using a change in the connection state between the front piston chamber 11a or the rear piston chamber 11b and the high-pressure circuit 124 or the low-pressure circuit 127 as a pilot signal.

[0039] Therefore, for example, the pilot pressure for switching the connection state is not limited to a configuration in which pilot pressure is obtained from the accumulator switching passage 128, but may be configured to be obtained from the valve control passage 125 of the piston rear chamber 11b, or even if pilot pressure is obtained from the first control valve 30, it is possible to have it function to switch to the desired connection state. Furthermore, the hydraulic breaker 10 of the first embodiment has been described as an example of a hydraulic impact device of the present invention, which is a rear chamber switching type (front chamber always connected to high pressure - rear chamber high / low pressure switching), but is not limited to this.

[0040] In other words, the hydraulic impact device according to the present invention can be applied to a hydraulic impact device of the front chamber switching type (rear chamber always connected to high pressure - front chamber high / low pressure switching), and can also be applied to a hydraulic drifter, as well as a hydraulic impact device of the front and rear chamber switching type (front and rear chamber high / low pressure switching) like the hydraulic drifter exemplified in the above-mentioned Patent Document 1. Below, other embodiments will be described. Note that the same or corresponding components as those in the first embodiment will be given the same reference numerals, and their description will be omitted as appropriate.

[0041] [Second embodiment] 6(a) and 6(b) are schematic diagrams illustrating a second embodiment (switchable front chamber + two accumulators) of a hydraulic impact device according to one aspect of the present invention. The hydraulic impact device of the second embodiment is an example of a front chamber switching type in which the piston rear chamber 11b is always connected to the high pressure circuit 124, and the first control valve 30, which is a switching valve mechanism, alternately switches the piston front chamber 11a between the high pressure circuit 124 and the low pressure circuit 127 to drive the piston 15. In the front chamber switching type cylinder 11, one end of a front chamber passage 129 is connected to the piston front chamber 11a, and the other end of the front chamber passage 129 is connected to a secondary port of a first control valve 30. In addition, the primary port of the first control valve 30, which is a switching valve mechanism, is connected to a low pressure circuit 127 and a high pressure circuit 124, respectively.

[0042] In the example of the second embodiment, there are provided a switching accumulator 21 and a second accumulator 22. The second accumulator 22 is provided as a high-pressure accumulator in the high-pressure circuit 124. The switching accumulator 21 is connected to a secondary port of the second control valve 40, and the primary port of the second control valve 40 is connected to the low-pressure circuit 127 and the high-pressure circuit 124, respectively. The second control valve 40 operates as an accumulator control valve in response to the pilot pressure in the accumulator switching passage 128, and switches its own oil passage depending on the pressure difference between the pressure in the piston front chamber 11a and the pressure in the high-pressure circuit 124. As a result, even in the switching accumulator 21 of the second embodiment, it is possible to suppress a surge in the low-pressure circuit 127 when the piston 15 retracts, while enabling a sufficient supply of pressurized oil when the piston 15 strikes.

[0043] [Third embodiment] 7A and 7B are schematic diagrams illustrating a third embodiment of a hydraulic impact device (front / rear chamber switchable type + two accumulators) according to one aspect of the present invention. The hydraulic impact device of the third embodiment is an example of a front and rear chamber switching type in which the first control valve 30 alternately switches the piston front chamber 11a and the piston rear chamber 11b between the high pressure circuit 124 and the low pressure circuit 127 to drive the piston 15. In the front / rear chamber switching type cylinder 11, one end of a front chamber passage 129 is connected to the piston front chamber 11a, and one end of a rear chamber passage 126 is connected to the piston rear chamber 11b. The other ends of the front chamber passage 129 and the rear chamber passage 126 are connected to secondary ports of a first control valve 30. Furthermore, the primary ports of the first control valve 30 of the third embodiment are connected to the low-pressure circuit 127 and the high-pressure circuit 124, respectively.

[0044] In the example of the third embodiment, there are provided a switching accumulator 21 and a second accumulator 22. The second accumulator 22 is provided as a high-pressure accumulator in the high-pressure circuit 124. The switching accumulator 21 is connected to a secondary port of the second control valve 40, and the primary port of the second control valve 40 is connected to the low-pressure circuit 127 and the high-pressure circuit 124, respectively. The second control valve 40 of the third embodiment operates as an accumulator control valve in response to the pilot pressure in the accumulator switching passage 128, and switches its own oil passage according to the pressure difference between the pressure in the piston rear chamber 11b and the pressure in the high-pressure circuit 124. As a result, the switching accumulator 21 of the third embodiment also makes it possible to suppress a surge in the low-pressure circuit 127 when the piston 15 retracts, while enabling a sufficient supply of pressurized oil when the piston 15 strikes.

[0045] [Fourth embodiment] 8A and 8B are schematic diagrams illustrating a fourth embodiment (rear chamber switching type + one accumulator) of a hydraulic impact device according to one aspect of the present invention. These diagrams differ from the first embodiment shown in FIG. 5 in that the device does not have the second accumulator 22. However, the switching accumulator 21 of the fourth embodiment also allows for sufficient supply of pressure oil when the piston 15 strikes, while suppressing surges in the low-pressure circuit 127 when the piston 15 retracts.

[0046] [Fifth embodiment] 9A and 9B are schematic diagrams illustrating a fifth embodiment (switchable front chamber + one accumulator) of a hydraulic impact device according to one aspect of the present invention. Although this embodiment differs from the second embodiment shown in FIG. 6 in that it does not have the second accumulator 22, the switching accumulator 21 of the fifth embodiment also allows for sufficient supply of pressure oil when the piston 15 strikes, while suppressing surges in the low-pressure circuit 127 when the piston 15 retracts.

[0047] [Sixth embodiment] 10A and 10B are schematic diagrams illustrating a sixth embodiment of a hydraulic impact device (front / rear chamber switching type + one accumulator) according to one aspect of the present invention. Although the sixth embodiment differs from the third embodiment shown in FIG. 7 in that it does not have the second accumulator 22, the switching accumulator 21 of the sixth embodiment also allows for sufficient supply of pressure oil when the piston 15 strikes, while suppressing surges in the low-pressure circuit 127 when the piston 15 retracts.

[0048] [Correspondence with each aspect shown in "Means for Solving the Problems"] As explained above, the hydraulic impact device according to the first aspect of the present invention shown in the "Means for Solving the Problems" can be applied to "rear chamber switching type" and "front / rear chamber switching type" hydraulic impact devices, as shown in the configuration examples of Figures 8 and 10 in the above embodiment. Similarly, the hydraulic impact device according to the second aspect of the present invention can be applied to all hydraulic impact devices, including the "rear chamber switching type," "front chamber switching type," and "front and rear chamber switching type," as shown in the configuration examples of Figures 8, 9, and 10 in the above embodiment. Furthermore, the hydraulic impact device according to the third aspect can be applied to all hydraulic impact devices, including the "rear chamber switching type," "front chamber switching type," and "front and rear chamber switching type," as shown in the configuration examples of Figures 5, 6, and 7 in the above embodiment. Furthermore, as shown in the configuration examples of Figures 5 and 6 in the above embodiment, the hydraulic impact device of the fourth aspect can be applied to "rear chamber switching type" and "front chamber switching type" hydraulic impact devices because the second accumulator 22 is dedicated to high pressure. [Explanation of symbols]

[0049] 10 Hydraulic breaker (hydraulic impact device) 11 cylinders 11a Piston front chamber 11b Piston rear chamber 12 Front Head 13 Buckhead 14 Chisel (striking rod) 15 pistons 16 Cylinder liner 17 Seal retainer 18 Front cover 19 Front holder 20 through bolt 21 Switching accumulator 22 Second accumulator 30 First control valve 40 Second control valve (accumulator control valve) 50 Stroke Adjustment Valve 101 Valve housing 102 Valve retainer 105 Valve chamber space 106 Valve 107 Medium diameter part 108 Large diameter section 109 Small diameter section 110 Communication groove 111 Cover 112 volts 113 Plug 114 Valve Control Room 115 Drainage chamber 116 Low pressure communication chamber 117 High-pressure communication chamber 121 Low-pressure accumulator 122 High-pressure accumulator 123 Stroke adjustment passage 124 High-voltage circuit 125 Valve control passage 126 Rear Passage 127 Low-voltage circuit 128 Accumulator switching passage 129 Anteroom passageway 201 Valve retainer 202A Valve Retainer (A) 202B Valve Retainer (B) 205 Valve chamber space 206 Switching valve 207 Medium diameter section 208 Large diameter valve 209 Small diameter valve 210 Communication groove 214 Valve Control Room 215 Oil drain room 216 Low-pressure communication chamber 217 High-pressure communication chamber CL1 First control valve axis CL2 Second control valve axis P Hydraulic pump T Tank

Claims

1. A hydraulic impact mechanism comprising a cylinder, a piston having a large diameter portion slidably fitted into the cylinder so as to be able to move forward and backward, a switching valve mechanism for controlling the forward and backward movement of the piston, and a striking rod to which a striking force is applied by the piston, wherein the large diameter portion of the piston defines a front piston chamber and a rear piston chamber at the front and rear of the axial direction of the cylinder, and the switching valve mechanism switches the connection destination of at least one of the front piston chamber and the rear piston chamber to a high pressure circuit supplied with pressurized oil from a hydraulic pump or a low pressure circuit connected to a tank, and wherein the front piston chamber is connected to the high pressure circuit and the rear piston chamber is connected to the switching valve mechanism, or a front and rear chamber switching type hydraulic impact mechanism wherein the front piston chamber and the rear piston chamber are each connected to the switching valve mechanism and switched to different connection destinations, a switching accumulator; an accumulator control valve capable of switching a connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit, the accumulator control valve connects the switching accumulator to the high-pressure circuit and disconnects it from the low-pressure circuit during a forward stroke of the piston, and connects the switching accumulator to the low-pressure circuit and disconnects it from the high-pressure circuit during a retraction stroke of the piston.

2. A hydraulic impact mechanism comprising a cylinder, a piston having a large diameter portion slidably fitted into the cylinder so as to be able to move forward and backward, a switching valve mechanism for controlling the forward and backward movement of the piston, and a striking rod to which striking force is applied by the piston, wherein the large diameter portion of the piston defines a front piston chamber and a rear piston chamber at the front and rear of the axial direction of the cylinder, and the switching valve mechanism switches the connection destination of at least one of the front piston chamber and the rear piston chamber to a high pressure circuit supplied with pressurized oil from a hydraulic pump or a low pressure circuit connected to a tank, and the front piston chamber is connected to the switching valve mechanism and the rear piston chamber is connected to the high pressure circuit, a switching accumulator; an accumulator control valve capable of switching a connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit, the accumulator control valve connects the switching accumulator to the low-pressure circuit and disconnects it from the high-pressure circuit during a forward stroke of the piston, and connects the switching accumulator to the high-pressure circuit and disconnects it from the low-pressure circuit during a retraction stroke of the piston.

3. A hydraulic impact mechanism comprising a cylinder, a piston having a large diameter portion slidably fitted into the cylinder so as to be able to move forward and backward, a switching valve mechanism for controlling the forward and backward movement of the piston, and a striking rod to which a striking force is applied by the piston, wherein the large diameter portion of the piston defines a front piston chamber and a rear piston chamber at the front and rear of the axial direction of the cylinder, and the switching valve mechanism switches the connection destination of at least one of the front piston chamber and the rear piston chamber to a high pressure circuit supplied with pressurized oil from a hydraulic pump or a low pressure circuit connected to a tank, and wherein the front piston chamber is connected to the high pressure circuit and the rear piston chamber is connected to the switching valve mechanism, or a front and rear chamber switching type hydraulic impact mechanism wherein the front piston chamber and the rear piston chamber are each connected to the switching valve mechanism and switched to different connection destinations, a switching accumulator; a second accumulator; and an accumulator control valve capable of switching a connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit, the second accumulator is always connected to the high-voltage circuit, the accumulator control valve connects the switching accumulator to the high-pressure circuit and disconnects it from the low-pressure circuit during a forward stroke of the piston, and connects the switching accumulator to the low-pressure circuit and disconnects it from the high-pressure circuit during a retraction stroke of the piston.

4. A hydraulic impact mechanism comprising: a cylinder; a piston having a large diameter portion slidably fitted into the cylinder so as to be able to move forward and backward; a switching valve mechanism for controlling the forward and backward movement of the piston; and a striking rod to which striking force is applied by the piston, wherein the large diameter portion of the piston defines a front piston chamber and a rear piston chamber at the front and rear of the axial direction of the cylinder, and the switching valve mechanism switches the connection destination of at least one of the front piston chamber and the rear piston chamber to a high pressure circuit supplied with pressurized oil from a hydraulic pump or a low pressure circuit connected to a tank, wherein the front piston chamber is connected to the switching valve mechanism and the rear piston chamber is connected to the high pressure circuit, a switching accumulator; a second accumulator; and an accumulator control valve capable of switching a connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit, the second accumulator is always connected to the high-voltage circuit, the accumulator control valve connects the switching accumulator to the low-pressure circuit and disconnects it from the high-pressure circuit during a forward stroke of the piston, and connects the switching accumulator to the high-pressure circuit and disconnects it from the low-pressure circuit during a retraction stroke of the piston.

5. A hydraulic impact mechanism comprising: a cylinder; a piston having a large diameter portion slidably fitted into the cylinder so as to be able to move forward and backward; a switching valve mechanism for controlling the forward and backward movement of the piston; and a striking rod to which a striking force is applied by the piston, wherein the large diameter portion of the piston defines a front piston chamber and a rear piston chamber at the front and rear of the axial direction of the cylinder, and the switching valve mechanism switches the connection destination of at least one of the front piston chamber and the rear piston chamber to a high pressure circuit supplied with pressurized oil from a hydraulic pump or a low pressure circuit connected to a tank, and wherein the front piston chamber is connected to the high pressure circuit and the rear piston chamber is connected to the switching valve mechanism, or the front piston chamber is connected to the switching valve mechanism and the rear piston chamber is connected to the high pressure circuit, a switching accumulator; a second accumulator; and an accumulator control valve capable of switching a connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit, The second accumulator is directly connected to the piston front chamber or the piston rear chamber, which is always connected to a high pressure. the accumulator control valve connects the switching accumulator to the low-pressure circuit and disconnects it from the high-pressure circuit during a forward stroke of the piston, and connects the switching accumulator to the high-pressure circuit and disconnects it from the low-pressure circuit during a retraction stroke of the piston.

6. A hydraulic impact device as described in any one of claims 1 to 5, wherein the accumulator control valve is configured to switch the connection destination of the switching accumulator between the high-pressure circuit and the low-pressure circuit by switching its own oil path using a change in the connection state of the piston front chamber or the piston rear chamber with the high-pressure circuit or the low-pressure circuit as a pilot signal.

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