JP2019155547A - Liquid pressure type striking device - Google Patents

Abstract

To provide a liquid pressure type striking device comprising high stability of an operation of an auto stroke mechanism for controlling a stroke of a piston.SOLUTION: A liquid pressure type striking device comprises: a cylinder 100 comprising three ports SP105, MP106, LP107; a piston 120 which is slidably fitted to inside of the cylinder 100; a piston front chamber 101 and a piston rear chamber 102 defined between an outer peripheral surface of the piston 120 and an inner peripheral surface of the cylinder 100; a first control valve 200 for switching at least one of the piston front chamber 101 and piston rear chamber 102 to at least one of a high tension circuit 110 and a low tension circuit 111, for driving the piston 120 at the selected stroke; a second control valve 300 for selecting the stroke of the first control valve 200 according to a forward/rearward movement position of the piston 120 to the three ports SP, MP, LP; and a control pressure holding mechanism for holding a pressure reception state of the switching control port 315 of the second control valve 300.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic striking device such as a rock drill or a breaker, and more particularly to a technique for automatically switching a piston stroke to a stroke selected from one of a short stroke and a long stroke.

  With this type of hydraulic hammering device, the stroke of the piston is automatically switched to one of the short stroke and long stroke according to the hardness of the rock subject to crushing (the amount of penetration into the rock). Various techniques (hereinafter referred to as “auto stroke mechanism”) for reducing excessive load on the striking portion such as the rod and the rod pin by appropriately adjusting the force have been proposed.

  The applicant has a short stroke port SP, a long stroke port LP and a cylinder having a stroke control port MP provided at a position between these two ports, a piston slidably fitted in the cylinder, and an outer periphery of the piston. The piston is selected by switching at least one of the piston front chamber and the piston rear chamber, the piston front chamber and the piston rear chamber defined between the surface and the inner peripheral surface of the cylinder to at least one of the high pressure circuit and the low pressure circuit. Proposed a hydraulic striking device with a drive direction switching valve that drives with a different stroke and a stroke control valve that selects the stroke by the drive direction switching valve according to the forward / backward movement position of the piston with respect to the three ports SP, MP, LP (See Patent Document 1).

  According to the hydraulic striking device described in Patent Document 1, the stroke control provided in the cylinder as three ports for stroke control, the short stroke port SP, the long stroke port LP, and the position between these two ports. Port MP is provided, and the stroke control valve selects the stroke by the drive direction switching valve according to the forward / backward movement position of the piston with respect to the three ports. The stroke of the piston can be automatically switched by simply switching the oil passages based on the positions of the three ports set in accordance with the forward / backward movement position of the piston.

Japanese Unexamined Patent Publication No. 2017-127717

  In the case of applying this hydraulic striking device to a hydraulic breaker, the applicant of the present application maintains the stop state, that is, the spool switching position, in order to stably operate the autostroke mechanism. I found it important. This is because the hydraulic breaker is premised on a long striking cycle time, and it is not possible to secure a sufficient seal length between adjacent ports in the three ports SP, MP, LP of the cylinder. This is because a state occurs in which the spool of the cylinder cannot maintain the switching position.

  For example, if the bedrock is hard, the stroke control valve will continue to stop at the long stroke position until the signal for switching to the short stroke position is applied after the spool is switched to the long stroke position. Is required. For this purpose, the holding pressure acting on the control port of the stroke control valve must maintain a predetermined value.

However, the pressure oil in the control port leaks and the holding pressure falls below a predetermined value, which may make it difficult for the stroke control valve spool to continue to stop at the long stroke position. On the other hand, the present applicant, as a means for compensating for a decrease in the holding pressure of the control port of the stroke control valve, provides a technique for providing a central passage having a throttle valve in the spool of the stroke control valve (hereinafter referred to as “high pressure holding mechanism”). ) Has been proposed.
This high pressure holding mechanism is set so that the high pressure port and the control port communicate with each other when the spool of the stroke control valve is switched to the long stroke position. Pressure oil is supplied to the port and acts to balance (for details, see FIG. 9 of JP-A-2017-127717 and the related description).

  On the other hand, if the bedrock is soft, the stroke control valve will stop at the short stroke position until the signal for switching to the long stroke position is applied to the control port after the spool is switched to the short stroke position. It is required to continue doing. For this purpose, the control port of the stroke control valve must be maintained in a low pressure state. However, even if the control port is connected to a low pressure, there may be a situation where pressure oil leaks from the high pressure circuit and flows in, making it difficult to keep the spool of the stroke control valve at the short stroke position.

  In such a case, it is necessary to switch to the short stroke to adjust the striking force appropriately in response to the soft rock, and the stroke of the stroke control valve spool cannot maintain the short stroke position and the long stroke and long stroke. There is a risk that the piston may operate in the middle stroke or completely long stroke.

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide a hydraulic striking device in which the operation of the stroke control valve of the auto stroke mechanism is stable.

The applicant of the present invention may not be sufficient to provide a holding mechanism for holding a long stroke position, like an automatic stroke mechanism of a conventional hydraulic striking device, and means for holding a short stroke position ( It has been found that it is also preferable to provide a “control pressure holding mechanism” hereinafter.
That is, in order to solve the above-described problem, a hydraulic striking device according to an aspect of the present invention is configured to move a piston forward and backward in a cylinder by a stroke selected from one of a short stroke and a long stroke, and to provide a striking rod. A hydraulic striking device for striking, wherein the cylinder has a short stroke port, a long stroke port, and a stroke control port provided at a position between the two ports as three ports for stroke control, and the cylinder The piston slidably fitted inside the piston, the piston front chamber and the piston rear chamber defined between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder and spaced apart in the axial direction; and At least one of the high pressure circuit and the low pressure circuit is connected to at least one of the piston front chamber and the piston rear chamber. A first control valve that drives the piston with the selected stroke, a switching control port that changes a pressure receiving state corresponding to the forward / backward movement position of the piston with respect to the three ports, and a pressure received by the switching control port A second control valve having a spool positioned at either a long stroke position or a short stroke position according to a state and selecting the stroke of the first control valve according to the position of the spool; and the second control valve Control pressure holding mechanism for holding the pressure receiving state of the switching control port when the spool of the second control valve is in the long stroke position and the pressure receiving state of the switching control port when the spool of the second control valve is in the short stroke position And.

Here, in the hydraulic striking device according to one aspect of the present invention, the control pressure holding mechanism connects the switching control port and the high pressure circuit when the spool of the second control valve is in the long stroke position. It is preferable to include a high pressure holding means for connecting, and a low pressure holding means for connecting the switching control port and the low pressure circuit when the spool of the second control valve is in the short stroke position.
In the hydraulic striking device according to one aspect of the present invention, the control pressure holding mechanism communicates the switching control port with the stroke control port only when the pressure oil needs to be discharged from the switching control port. In other cases, it is preferable that the on-off valve shuts off the communication between the switching control port and the stroke control port.

According to the hydraulic striking device according to one aspect of the present invention, the cylinder has three stroke control ports, a short stroke port, a long stroke port, and a stroke control port provided at a position between these two ports. Since the second control valve selects the stroke by the first control valve according to the forward / backward movement position of the piston with respect to the three ports, the second control valve has a simple structure without a throttle, and the bedrock The piston stroke can be automatically switched by simply switching the oil passages based on the positions of the three ports set in accordance with the forward / backward movement position of the piston.
In the hydraulic striking device according to one aspect of the present invention, the pressure receiving state of the switching control port when the spool of the second control valve is in the long stroke position, and the spool of the second control valve are in the short stroke position. Since the control pressure holding mechanism that holds the pressure receiving state of the switching control port at a certain time is provided, the operation of the second control valve is stabilized. Therefore, the operation stability of the auto stroke mechanism that controls the stroke of the piston is high.

  As described above, according to the present invention, it is possible to provide a hydraulic striking device with high operational stability of an auto stroke mechanism that controls the stroke of a piston.

It is explanatory drawing of 1st Embodiment of the hydraulic striking device provided with the autostroke mechanism which concerns on 1 aspect of this invention, In the same figure, the state of each part when a piston is located in a front dead center is shown. . In addition, in the same figure, the cross section along the axis line of each part is shown about the principal part of a hydraulic striking device (Hereinafter, it is the same in other figures). It is a figure explaining operation | movement of the autostroke mechanism of the hydraulic striking device of FIG. 1 (hereinafter, the same applies to FIGS. 3 to 8). In this figure, the piston is retracted from the front dead center to the short stroke port during operation. The state of each part is shown. This figure shows the state of each part when the reset port is operated while the piston is moving forward with a short stroke. In the same figure, the state of each part when the piston moves forward and starts retreating at the striking point is shown. The figure shows the state of each part when the piston moves back to the long stroke port when the piston moves backward at the striking point. The figure shows the state of each part when the piston moves forward to the position of the stroke switching port when the piston moves forward beyond the striking point. This figure shows the state of each part when the piston moves backward to the short stroke port after the piston moves forward beyond the striking point. This figure shows the state of each part when the reset port is operated while the piston is moving forward with a short stroke. It is explanatory drawing which shows the detail of the 2nd control valve of an autostroke mechanism of the hydraulic striking device of FIG. It is explanatory drawing of 2nd Embodiment of the hydraulic striking device provided with the auto stroke mechanism which concerns on 1 aspect of this invention, In the same figure, the state of each part when a piston is located in a front dead center is shown. . It is explanatory drawing of the modification of 2nd Embodiment of the hydraulic striking device provided with the automatic stroke mechanism which concerns on 1 aspect of this invention, In this figure, the state of each part when a piston is located in a front dead center is shown. Show. It is explanatory drawing of 3rd Embodiment of the hydraulic striking device provided with the auto stroke mechanism which concerns on 1 aspect of this invention, In the same figure, the state of each part when a piston is located in a front dead center is shown. .

  Hereinafter, embodiments or modifications of the present invention will be described with reference to the drawings as appropriate. The drawings are schematic. For this reason, it should be noted that the relationship between the thickness and the planar dimension, the ratio, and the like are different from the actual ones, and the dimensional relationship and the ratio are different between the drawings. Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, and arrangement of components. Etc. are not specified in the following embodiments or modifications.

[First Embodiment]
As shown in FIG. 1, the hydraulic striking device according to the first embodiment includes a cylinder 100 and a piston 120, and a first control valve 200 and a second control valve 300 are provided separately from the cylinder 100. ing. A valve 201 is slidably fitted inside the first control valve 200, and a spool 330 is slidably fitted inside the second control valve 300.
A back head 400 is attached to the rear portion of the cylinder 100. The back head 400 is filled with a high-pressure back head gas G. A front head 500 is attached to the front portion of the cylinder 100. A rod 501 is slidably fitted inside the front head 500.

  The piston 120 is a solid cylindrical body, and has a front large-diameter portion 121 and a rear large-diameter portion 122 as two large-diameter portions at substantially the center thereof. An intermediate diameter portion 123 is provided in front of the front large diameter portion 121, and a small diameter portion 124 is provided behind the rear large diameter portion 122. Is provided with an annular groove 125.

The piston 120 is slidably fitted into the cylinder 100, so that a piston front chamber 101 and a piston rear chamber 102 are defined on the front and rear sides of the cylinder 100, respectively. The front chamber port 103 is provided in the piston front chamber 101, and the front chamber port 103 is always connected to the high-pressure circuit 110 through the front chamber passage 112.
A rear chamber port 104 is provided in the piston rear chamber 102. The rear chamber port 104 and the first control valve 200 are connected by a rear chamber passage 113. The piston rear chamber 102 can communicate with the high-pressure circuit 110 and the low-pressure circuit 111 alternately by forward / reverse switching by the valve 201 of the first control valve 200. Note that an accumulator (not shown) is provided at an appropriate position of the high-voltage circuit 110.

The outer diameter of the medium diameter portion 123 is set larger than the outer diameter of the small diameter portion 124. Accordingly, the pressure receiving area of the piston 120 in the piston front chamber 101 and the piston rear chamber 102 (that is, the diameter difference between the front large diameter portion 121 and the medium diameter portion 123 and the diameter difference between the rear large diameter portion 122 and the small diameter portion 124). Is larger on the piston rear chamber 102 side.
Thus, when the piston rear chamber 102 is connected to the high pressure by the operation of the valve 201, the piston 120 moves forward due to the pressure receiving area difference, and when the piston rear chamber 102 is connected to the low pressure by the operation of the valve 201, the piston 120 moves backward. It has become.

  In the cylinder 100, a short stroke port 105, a stroke control port 106, a long stroke port 107, and a low pressure port 108 are arranged in the axial direction between the front chamber port 103 and the rear chamber port 104 in order from the front to the rear. It is provided in a separated position.

  In the hydraulic striking device according to the first embodiment, the rod is moved forward and backward in the cylinder 100 by a stroke automatically selected according to the condition of the rock from one of a long stroke and a short stroke shorter than the long stroke. Although the automatic stroke mechanism for hitting 501 is provided, the short stroke port 105, the stroke control port 106, and the long stroke port 107 constitute a part of the automatic stroke mechanism of the present invention.

  The first control valve 200 has a valve chamber 212 formed non-coaxially with the piston 120 inside, and the valve 201 is slidably fitted into the valve chamber 212. The valve chamber 212 includes a medium-diameter valve front chamber 213, a large-diameter valve main chamber 214, and a small-diameter valve rear chamber 215 in order from the front to the rear. A front chamber passage 223 that is always in communication with the high-pressure circuit 110 is connected to the valve front chamber 213.

  The valve main chamber 214 is provided with a front low pressure port 218, a reset port 219, a valve control port 220, and a rear low pressure port 221 in order from the front to the rear, and a rear chamber port 222 is provided in the valve rear chamber 215. It has been. The front low pressure port 218 always communicates with the low pressure circuit 111 via the front low pressure passage 224, and the rear low pressure port 221 always communicates with the low pressure circuit 111 via the rear low pressure passage 227. The valve control port 220 and the valve control port 107 communicate with each other via a valve control passage (direct connection) 114. The rear chamber port 222 and the rear chamber port 104 communicate with each other via the rear chamber passage 113.

  The valve 201 is a hollow cylindrical body, and has a medium diameter portion 202, a large diameter portion 203, and a small diameter portion 204 in order from the front to the rear. A hollow passage 228 inside the cylinder always communicates with the high-voltage circuit 110 through the front chamber passage 223. In the valve 201, an oil drain groove 205 for switching the piston rear chamber 102 between a high pressure and a low pressure is provided in an annular shape on the outer peripheral surface at the substantially center of the small diameter portion 204. A communication hole 210 is formed in the radial direction of the valve 201 in front of the oil draining groove 205 of the valve 201, and a slit groove 211 is formed in the axial direction on the outer peripheral surface of the front side of the large diameter portion 203. It is formed in a slit shape along.

The valve 201 is always urged rearward due to the pressure receiving area difference between the medium diameter portion 202 and the small diameter portion 204, and when high pressure oil is supplied to the valve control port 220, the rear diameter step of the large diameter portion 203 is performed. The pressure receiving area of the surface 209 is added to move forward.
When the valve 201 is at the rear end position, that is, when the rear end surface 207 is in contact with the valve chamber rear end surface 217, the rear chamber port 222 is interposed by the oil drain groove 205 via the rear low pressure port 221 and the rear low pressure passage 227. Therefore, the piston rear chamber 102 is connected to a low pressure.

  On the other hand, when the valve 201 is in the front end position, that is, when the front end surface 206 is in contact with the valve chamber front end surface 216, the rear chamber port 222 is disconnected from the rear low pressure port 221 and the rear end surface 207. And the valve chamber rear end face 217 and the valve chamber 212 connected to each other at high pressure via the hollow passage 228, the piston rear chamber 102 is connected at high pressure.

Here, the hydraulic breaker requires a holding mechanism for maintaining the high or low pressure of the valve control port 220 in order for the valve 201 to maintain the stop state at the switching position between the front end and the rear end.
In the present embodiment, the holding mechanism when the valve 201 is at the rear end position is the slit groove 211. When the valve 201 is at the rear end position, the slit groove 211 connects the valve control port 220, the reset port 219, and the front low pressure port 218 to ensure that the rear stepped surface 209 is low-pressure connected. The stop state is maintained.

  The holding mechanism when the valve 201 is at the front end position is the communication hole 210. When the valve 201 is at the front end position, the communication hole 210 prevents the holding pressure from being lowered by replenishing the valve control port 220 (and the reset port 219) with pressure oil from the hollow passage 228. It is designed to maintain the stopped state.

  The hydraulic striking device according to the first embodiment includes a second control valve 300 provided on the side surface of the cylinder 100 adjacent to the first control valve 200, and the second control valve 300 is the main control valve 300. It functions as a stroke control valve that constitutes a part of the auto stroke mechanism of the invention. In FIG. 1, for convenience of explanation, the second control valve 300 is illustrated at a separated position.

  In the second control valve 300, a first sleeve 302 and a second sleeve 303 are loaded in a substantially rectangular parallelepiped housing 301, and a spool chamber 305 is formed by the first sleeve 302 and the second sleeve 303. . The axial positions of the first sleeve 302 and the second sleeve 303 are fixed by tightening a plug 304 screwed into the upper opening of the housing 301.

  In the spool chamber 305, a small diameter portion 306, a large diameter portion 307, and a medium diameter portion 308 are formed in order from the top to the bottom, and an upper end surface 309 is formed at the boundary between the small diameter portion 306 and the large diameter portion 307. A lower end surface 310 is formed at the boundary between the large diameter portion 307 and the medium diameter portion 308. A slit-like slit drain groove 311 is formed at a plurality of locations below the middle diameter portion 308.

  The spool 330 is slidably fitted into the spool chamber 305 so that the high-pressure chamber 312 is defined above the spool 330 and the control chamber 313 is defined below. The movement stroke of the spool 330 is controlled by the upper end surface 309 and an upper stepped surface 334 (described later) coming into contact with each other, and the lower end surface 310 and the lower stepped surface 335 (described later) contacting each other. The position is restricted.

  The spool 330 is a cylindrical member composed of a small-diameter portion 331, a large-diameter portion 332, and a medium-diameter portion 333 in order from the top to the bottom, and an upper step is provided at the boundary between the small-diameter portion 331 and the large-diameter portion 332. A surface 334 is formed, and a lower stepped surface 335 is formed at the boundary between the large diameter portion 332 and the medium diameter portion 333. An annular communication groove 336 is provided on the outer periphery of the large diameter portion 332.

  An annular drain groove 337 is provided on the proximal end side of the middle diameter portion 333, that is, on the lower stepped surface 335 side. The lower stepped surface 335 is provided with a plurality of drain passages 338 having an end surface groove shape. A central passage 339 is formed along the axial center of the spool 330, and a communication hole 340 is provided on the small diameter portion 331 side of the central passage 339 so as to penetrate in a direction orthogonal to the axial center. .

  The housing 301 is provided with a high-pressure port 314 that communicates with the high-pressure chamber 312, and a switching control port 315 that communicates with the control chamber 313. Further, the housing 301 is provided with a valve communication port 317 and a cylinder communication port 318 at a position facing the communication groove 336. A low pressure port 316 is provided between the high pressure port 314 and the valve communication port 317, and a drain port 319 is provided between the cylinder communication port 318 and the switching control port 315.

  The high-pressure port 314 communicates with the high-pressure circuit 110 through a high-pressure passage 320, and the high-pressure chamber 312 is always connected to high pressure. The switching control port 315 communicates with the stroke control port 106 through the stroke control passage 115 and communicates with the reset port 219 through the reset passage 225. In the reset port 219, a check valve 350 allows the flow of pressure oil from the reset port 219 side to the switching control port 315 side, and restricts the flow of pressure oil from the switching control port 315 side to the reset port 219 side. It is provided as follows.

  The low pressure port 316 communicates with the low pressure circuit 111 through a low pressure passage 321 and is always connected to a low pressure. The valve communication port 317 communicates with the valve control port 220 through a valve control passage (via a spool) 226. The cylinder communication port 318 communicates with the short stroke port 105 through the stroke switching passage 116.

  In the hydraulic striking device of the first embodiment, when the high pressure oil is supplied to the switching control port 315, the outer diameter of the medium diameter portion 333 is set larger than the outer diameter of the small diameter portion 331. The spool 330 is moved to the upper end position due to the pressure receiving area difference between the spool 312 and the control chamber 313. When the high pressure oil is not supplied to the switching control port 315, the spool 330 is shown in FIG. So that it moves to the lower end position.

  In the second control valve 300, when the spool 330 moves to the lower end position, the valve communication port 317 and the cylinder communication port 318 communicate with each other through the communication groove 336, and the short stroke port 105 and the valve control port 220 communicate with each other. The slit-shaped drain groove 311, the annular drain groove 337 and the drain passage 338 communicate with each other, and the control chamber 313 is connected to the drain port 319 while the communication hole 340 is closed, so that the high-pressure chamber 312 and the control chamber 313 Will not communicate.

  In addition, when the spool 330 moves to the upper end position, the second control valve 300 blocks communication between the valve communication port 317 and the cylinder communication port 318 and blocks communication between the control chamber 313 and the drain port 319. On the other hand, the high-pressure chamber 312 and the control chamber 313 communicate with each other through the communication hole 340 and the central passage 339.

  Hereinafter, the time when the spool 330 is moved to the upper end position is also referred to as “long stroke position”, and the time when the spool 330 is moved to the lower end position is also referred to as “short stroke position”. Further, as the forward / backward moving position of the piston 120, a position where the piston 120 has advanced a predetermined amount beyond the striking point during forward movement is also referred to as a “switching position”.

Next, the operation, action, and effect of the automatic stroke mechanism of the hydraulic striking device of the first embodiment will be described.
As shown in FIG. 1, in the hydraulic striking device, the piston 120 is subjected to a forward thrust F by the gas pressure G of the high-pressure gas sealed in the back head 400 before the operation. Therefore, the piston 120 becomes the position of the front dead center.

  At the start of operation of the hydraulic striking device, when the piston 120 is at the position of the front dead center, the spool 330 of the second control valve 300 has a high pressure chamber 312 shown in FIG. The control chamber 313 is connected to the circuit 110 through the switching control port 315, the stroke control passage 115, the stroke control port 106, the low pressure port 108, and the low pressure passage 117. For this reason, the spool 330 is pressed downward in the figure and is stopped at the “short stroke position”.

  At the start of operation, the first control valve 200 is supplied with high-pressure oil from the high-pressure circuit 110 via the high-pressure passage 223 to the valve front chamber 213, so that the valve 201 moves to the retracted position. When the valve 201 of the first control valve 200 is in the retracted position, the first control valve 200 connects the piston rear chamber 102 to the low pressure circuit 111 via the low pressure passage 227.

  When the hydraulic striking device is operated, the high pressure oil of the high pressure circuit 110 is supplied to the piston front chamber 101 via the high pressure passage 112, and the piston front chamber 101 is always connected to high pressure. On the other hand, when the valve 201 of the first control valve 200 is in the retracted position, the piston rear chamber 102 is at a low pressure, so that the piston 120 is urged rearward and starts moving backward.

  2, when the front end of the front large diameter portion 121 of the piston 120 is retracted to the position of the short stroke port 105 of the cylinder 100, it is introduced into the short stroke port 105 from the piston front chamber 101 that is always connected to high pressure. The high pressure oil thus introduced is introduced into the valve control port 220 of the first control valve 200 through the communication groove 336 of the spool 330 in the “short stroke position” within the second control valve 300 as shown in FIG. .

  In the first control valve 200, when high-pressure oil is supplied to the valve control port 220, the pressure receiving area of the rear stepped surface 209 is added and the valve 201 moves forward. As a result, the rear chamber port 222 communicates with the valve chamber 212 connected between the rear end surface 207 of the valve 201 and the rear end surface 217 of the valve chamber 212 and with the high pressure via the hollow passage 228. Are connected with high voltage. Therefore, since the piston rear chamber 102 becomes a high pressure, the piston 120 starts moving forward with a short stroke due to a difference in pressure receiving area thereof.

Here, in the auto stroke mechanism of the present embodiment, the check valve 350, the reset passage 225, and the reset port 219 are provided as means for supplying pressure oil to the switching control port 315 of the second control valve 300. is there.
That is, when the valve 201 of the first control valve 200 is switched to the forward position, the valve control port 220 and the reset port 219 communicate with each other by the rear stepped surface 209 as shown in FIG. Is supplied from the reset passage 225 to the switching control port 315 of the second control valve 300 via the check valve 350.

  As a result, as shown in the figure, the second control valve 300 causes the spool 330 to be pressed upward by the pressure receiving area difference between the small diameter part 331 and the medium diameter part 333 of the spool 330 to the “long stroke position”. Switch. At this time, the reset port 219 is supplemented with pressure oil from the communication hole 210 via the valve control port 220. Therefore, the pressure oil necessary for maintaining the stopped state of the valve 201 and operating the spool 330 of the second control valve 300 (moving the spool 330 upward in FIG. 3 and maintaining the stopped state after the movement) is sufficiently supplied. Is done.

  Next, the piston 120 moves forward, and as shown in FIG. 4, the position of the piston 120 at the impact point, that is, the rear end of the front large-diameter portion 121 of the piston 120 passes the position of the long stroke port 107 of the cylinder 100. Then, the low pressure port 108 of the cylinder 100 and the long stroke port 107 communicate with each other, and the valve control port 220 of the first control valve 200 is connected to a low pressure. As a result, the valve 201 of the first control valve 200 is pressed rearward to switch to the retracted position, and the piston rear chamber 102 becomes low pressure accordingly.

  Here, when the piston rear chamber 102 is at a low pressure, when the rock is hard, the piston 120 moves backward with a slight penetration amount. At this time, the switching control port 315 and the stroke control passage 115 are closed while the stroke control port 106 is closed by the front large-diameter portion 121 and the check valve 350 restricts the flow of pressure oil from the stroke control passage 115. Since the circuit is formed, the pressure oil in the control chamber 313 is held. Therefore, the spool 330 of the second control valve 300 maintains the “long stroke position”.

  In this way, when the rock is hard, the valve 201 is held at the “long stroke position” when the piston 120 moves backward, so that the front end of the front large-diameter portion 121 of the piston 120 is the short stroke of the cylinder 100. The high pressure oil introduced into the short stroke port 105 is blocked by the second control valve 300 and is not introduced into the first control valve 200 even when the port 105 is moved back to the position of the port 105. Therefore, the piston 120 can continue to retract.

  Further, even if the front end of the front large-diameter portion 121 of the piston 120 is retracted to the position of the stroke control port 106 of the cylinder 100, there is no room for high-pressure oil introduced into the stroke control port 106 to flow into the stroke control passage 115 side. Absent. Therefore, the operation of the second control valve 300 and the first control valve 200 is not affected, and the piston 120 can be continuously retracted. That is, according to this hydraulic striking device, when the rock is hard, the piston 120 can automatically perform striking with a long stroke.

  Next, as shown in FIG. 5, when the front end of the front large-diameter portion 121 of the piston 120 moves backward to the position of the long stroke port 107 of the cylinder 100, the long stroke port 107 communicates with the high pressure oil in the piston front chamber 101. Therefore, high-pressure oil is introduced into the valve control port 220 of the first control valve 200 via the long stroke port 107 and the valve control passage (direct connection) 114.

  As a result, the valve 201 moves to the forward position due to the pressure receiving area difference between the front and rear of the first control valve 200, and the rear chamber port 222 is located between the rear end surface 207 of the valve 201 and the rear end surface 217 of the valve chamber 212. And the valve chamber 212 connected to the high pressure via the hollow passage 228, the piston rear chamber 102 is connected to the high pressure, and the piston rear chamber 102 becomes high pressure. Therefore, the piston 120 starts moving forward due to the pressure receiving area difference between the front and rear of the piston 120.

  At this time, the hydraulic pressure oil of the first control valve 200 is introduced into the second control valve 300 from the reset port 219 to the switching control port 315 of the second control valve 300 via the check valve 350 of the reset passage 225. The Therefore, the spool 330 maintains the “long stroke position” in the upper portion of the drawing due to the pressure receiving area difference between the small diameter portion 331 and the middle diameter portion 333 above and below the spool 330.

  Here, when the bedrock is soft, even after the piston 120 hits the bedrock, the piston 120 further advances beyond the position of the hitting point shown in FIG. At this time, in the hydraulic striking device of this embodiment, as shown in FIG. 6, when the piston 120 further advances beyond the position of the striking point, the rear end of the front large-diameter portion 121 of the piston 120 is the cylinder 100. When the stroke control port 106 reaches the “switching position” where the stroke control port 106 is formed, the stroke control port 106 is connected to the low pressure port in order to communicate with the low pressure port 108. Therefore, the high-pressure oil in the switching control port 315 below the second control valve 300 is released, whereby the spool 330 of the second control valve 300 is pressed downward to switch to the “short stroke position”.

  Next, when the piston 120 moves backward and the front end of the front large-diameter portion 121 of the piston 120 moves backward to the position of the short stroke port 105 of the cylinder 100 as shown in FIG. 7, the second control valve 300 at this time is Since the spool 330 is in the “short stroke position”, the high pressure oil in the piston front chamber 101 is introduced from the short stroke port 105 into the valve control port 220 of the first control valve 200 through the communication groove 336 of the second control valve 300. The

  Therefore, the valve 201 of the first control valve 200 is switched to the forward position, and the piston rear chamber 102 becomes high pressure accordingly. Therefore, the piston 120 starts to advance in a short stroke due to a pressure receiving area difference between itself and the front and back. That is, according to this hydraulic striking device, when the rock is soft, the second control valve 300 is switched to the “short stroke position” at the “switching position”, and the piston 120 is automatically hit by the short stroke. It can be carried out.

When the valve 201 switches to the forward position, as shown in FIG. 8, the working pressure oil of the valve 201 introduced into the valve control port 220 is reversed from the reset port 219 of the first control valve 200 to the reset passage 225. It is introduced into the switching control port 315 of the second control valve 300 via the stop valve 350.
Thereby, the second control valve 300 is pressed upward due to the pressure receiving area difference between the small-diameter portion 331 and the medium-diameter portion 333 while the piston 120 is advanced by a short stroke and does not reach the “switching position”. Then, it switches to “long stroke position”. In other words, the second control valve 300 is reset from the short stroke state to the long stroke state.

  This long stroke state is the same as the state shown in FIG. Therefore, thereafter, in this hydraulic striking device, as described above, the piston 120 repeatedly moves forward and backward by the cooperation of the piston 120, the first control valve 200, and the second control valve 300 according to the hardness of the rock. When the rock 501 is hit while the rock is hard (that is, when the forward movement position of the piston 120 does not reach the “switching position”), as described with reference to FIGS. When the rock is soft (that is, when the forward movement position of the piston 120 has reached the “switching position”), as described with reference to FIGS. Moves back and forth with a short stroke.

  Therefore, according to this hydraulic striking device, the stroke of the piston 120 is automatically switched to a stroke selected from one of the short stroke and the long stroke according to the hardness of the rock (the amount of penetration into the rock). By appropriately adjusting the force, it is possible to reduce an excessive load on the striking portions such as the rod 501 and the rod pin.

Next, the control pressure holding mechanism provided in the automatic stroke mechanism of the hydraulic striking mechanism of the first embodiment will be described.
Here, in the hydraulic striking device of the present embodiment, when the spool 330 is in the long stroke position, the pressure oil in the stroke control port 106 of the cylinder 100 is held in the closed circuit, so the long stroke position is maintained. A configuration example to be described has been described.

  However, in the first embodiment described above, the stroke control port 106 at the time of closed circuit formation and the long stroke port 107 communicating with the low pressure port 108 are adjacent to each other, and it is generally the clearance that contacts this portion. Therefore, the pressure oil in the stroke control port 106 leaks to the low pressure port 108 via the long stroke port 107.

  This leak of pressure oil occurs immediately after the pressure oil is supplied from the reset passage 225 to the switching control port 315 and the spool 330 moves to the long stroke position. This is because the holding force of the control chamber 313 of the second control valve 300 is insufficient when the amount of oil supplied from the reset passage 225 is not sufficient with respect to the leak amount from the closed circuit to the low pressure port 108. The spool 330 may move from the upper long stroke position in the drawing to the lower stroke position in the drawing.

Therefore, in order to prevent the holding force from being insufficient due to the leak, the central passage 339 formed along the central axis direction of the spool 330 and opened to the control chamber 313, and the central passage when the spool 330 is in the long stroke position. It is preferable to provide a communication hole 340 formed at a position where 339 communicates with the high pressure chamber 312.
That is, the spool 330 has a central passage 339 that has one end opened to the pressure receiving surface side that receives the pressure of the hydraulic oil supplied to the stroke control port 106, that is, the control chamber 313 side, and the other end of the spool 330 is the spool 330. When in the long stroke position, the high pressure circuit 110 communicates with the high pressure chamber 312 via the communication hole 340.

  By providing the spool 330 with the central passage 339 and the communication hole 340, when the holding pressure of the switching control port 315 from the stroke control port 106 decreases due to the leak of pressure oil, the communication hole 340 and the central passage 339 are connected from the high pressure chamber 312 side. Passing through, the control chamber 313 is filled with pressure oil. When the high pressure chamber 312 and the control chamber 313 are balanced with high pressure oil, the spool 330 is held at the long stroke position due to the pressure receiving area difference. Therefore, even if a leak occurs, the long stroke position of the spool 330 can be held more reliably. The central passage 339 and the communication hole 340 constitute high-pressure holding means described in the means for solving the problems of the present invention.

  The passage area of the high pressure holding means is such that when the spool 330 moves to the long stroke position and the high pressure chamber 312 and the control chamber 313 communicate with each other, pressure oil leaks from the control chamber 313 to the low pressure port 108 side. When a pressure difference between the control chamber 313 and the control chamber 313 occurs, the pressure oil is immediately supplied from the high pressure chamber 312 to the control chamber 313 so as to ensure a flow rate to be balanced.

  If the passage area of the high pressure holding means is set smaller than the above set value, even if a pressure difference occurs between the high pressure chamber 312 and the control chamber 313, the amount of oil necessary for holding the spool 330 cannot be supplied quickly. The long stroke position cannot be held stably. On the other hand, if the passage area of the high-pressure holding means is made larger than the above set value, the spool 330 is turned on at the timing of switching the spool 330 to the short stroke position (in other words, the situation where the control chamber 313 is connected to the low pressure). Before moving to the short stroke position, the entire hydraulic circuit may drop below the operating pressure of the hydraulic striking device, and operation may become unstable.

In addition, the larger the passage area of the high-pressure holding means, the greater the amount of leakage that flows out from the control chamber port 315 to the low-pressure port 108, leading to a decrease in efficiency.
As described above, in the hydraulic striking device according to the present embodiment, the spool 330 of the second control valve 300 is provided with the central passage 339 and the communication hole 340, and the passage area is set appropriately, so that the spool 330 has a long stroke. The position can be stably held, and the switching operation to the short stroke position is not hindered.

In the hydraulic striking device of the present embodiment, when the spool 330 is in the short stroke position, the switching control port 315 has a low pressure via the stroke control passage 115, the stroke control port 106, the low pressure port 108, and the low pressure passage 117. Since it is connected to the circuit 111, the control room 313 is connected to a low voltage.
Here, the pressure oil in the piston front chamber 101 leaks to the stroke control port 106 side before the piston 120 moves backward and the front end of the front large-diameter portion 121 reaches the short stroke port 105, and passes through the stroke control passage 115. There is a case where the low pressure state of the control chamber 313 cannot be maintained by flowing into the switching control port 315.

  If the low pressure state of the control chamber 313 cannot be maintained, the spool 330 moves from the short stroke position to the long stroke position. At this time, the pressure oil in the piston front chamber 101 also leaks into the short stroke port 105 and passes through the stroke switching passage 116, the cylinder communication port 318, the communication groove 336, the valve communication port 317, and the valve control passage (via spool) 226. However, since the valve 201 is discharged from the low pressure circuit 111 via the slit groove 211, the reset port 219, the front low pressure port 218, and the front low pressure passage 224, the valve 201 does not operate.

  Therefore, in such a case, the automatic stroke mechanism must be operated in response to the soft rock, and the stroke control valve must adjust the striking force appropriately by switching to the short stroke. Since it cannot be maintained, the piston operates in the middle stroke between the short stroke and the long stroke, or in a completely long stroke state.

  Therefore, in order to prevent the occurrence of the phenomenon that the low pressure state cannot be maintained due to the inflow of the leaked pressure oil, in the hydraulic striking device of the present embodiment, the control chamber 313 is slit when the spool 330 is in the short stroke position. The drain port 319 communicates with the drain drain groove 311, the annular drain groove 337, and the drain passage 338, and is further connected to the low-voltage circuit 111 through the drain passage 322.

  Thereby, even when pressure oil flows into the switching control port 315 when the spool 330 is in the short stroke position, it can be released to the low pressure circuit. Therefore, the spool 330 can be held at the short stroke position while maintaining the low pressure state of the control chamber 313. Therefore, it is possible to surely adjust the striking force by switching to the short stroke corresponding to the soft rock. The drain passage formed by the slit-like drain groove 311, the annular drain groove 337, and the drain passage 338 constitutes a low-pressure holding means described in the means for solving the problems of the present invention.

  Since the passage area of the low pressure holding means is sufficiently small, when the spool 330 operates normally, that is, when a predetermined amount of high pressure oil is supplied to the switching control port 315 and the spool 330 moves to the long stroke position, However, when the spool 330 is stopped at the short stroke position and a small amount of pressure oil due to the leak gradually flows into the switching control port 315 and the pressure rises from the low pressure state, Oil drains and the low pressure state of the control chamber 313 can be stably maintained.

In the first embodiment, the high-pressure holding means and the low-pressure holding means constitute a control pressure holding mechanism described in the means for solving the problems of the present invention.
This control pressure holding mechanism holds the high pressure state of the switching control port 315 when the second control valve 300 is in the long stroke position, and the low pressure of the switching control port 315 when the second control valve 300 is in the short stroke position. Since it maintains the state, if it is preferable to hit with a long stroke according to the state of the object to be crushed, it can definitely hit with a long stroke, and if it is preferable to hit with a short stroke, it can definitely hit with a short stroke. It becomes possible.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the spool 330 ′ of the second control valve 300 ′ does not include the central passage 339, the communication hole 340, the annular drain groove 337, and the drain passage 338, and the second sleeve 303 ′ is slit. The conical drain groove 311 is not provided. That is, the second embodiment does not include the high pressure holding means and the low pressure holding means in the first embodiment. Instead, in the second embodiment, the on-off valve 360 is provided in the stroke control passage 115 as a control pressure holding mechanism.

  The pilot passage 361 of the on-off valve 360 is connected to the stroke control passage 115 and the reset passage 225 via the shuttle valve 362. The on-off valve 360 is normally switched to the open position, and is switched to the closed position when pressure oil flows into the switching control port 315 side in the stroke control passage 115 or the reset passage 225. That is, in the second embodiment, the on-off valve 360, the pilot passage 361, and the shuttle valve 362 constitute a control pressure holding mechanism described in the means for solving the problems of the present invention.

The operation of the on-off valve 360 will be described.
When high pressure oil is supplied to the valve control port 220 and the valve 201 moves forward, the pressure oil in the valve control port 220 is supplied to the switching control port 315 via the reset port 219 and the reset passage 225. When high pressure oil is supplied to the switching control port 315, the control chamber 313 is connected to high pressure, and the spool 330 ′ moves to the long stroke position due to the pressure receiving area difference between the control chamber 313 and the high pressure chamber 312.

  At this time, the on-off valve 360 is switched to the closed position because the pressure oil from the reset passage 225 is supplied to the pilot passage 361 via the shuttle valve 362. Therefore, the communication state between the switching control port 315 and the stroke control passage 115 is cut off, and the pressure oil is prevented from leaking from the control chamber 313 to the low pressure port 108, so that the spool 330 ′ maintains the long stroke position. Is possible.

  When the hydraulic striking device strikes a soft rock, the piston 120 moves forward beyond the position of the striking point. When the rear end of the front large-diameter portion 121 of the piston 120 reaches the stroke control port 106 of the cylinder 100, the stroke control port 106 is connected to the low pressure because it communicates with the low pressure port 108, whereby the stroke control passage 115 is connected. Since the low pressure connection is established, the open / close valve 360 is switched to the open position, and the high pressure oil in the switching control port 315 is opened, so that the spool 330 ′ is switched to the short stroke position.

  Next, when the piston 120 turns backward and the front end of the front large-diameter portion 121 retracts to the short stroke port 105, as described above, the hydraulic striking mechanism operates with a short stroke by the auto stroke mechanism. If the pressure oil in the piston front chamber 101 leaks from the stroke control port 106 to the stroke control passage 115 at this stage, the on-off valve 360 is switched to the closed position.

  Therefore, the communication state between the switching control port 315 and the stroke control passage 115 is blocked, and the pressure oil is prevented from leaking from the piston front chamber 101 to the control chamber 313, so that the spool 330 ′ can maintain the short stroke position. It becomes possible.

  As described above, according to the second embodiment, the on-off valve 360, the pilot passage 361, and the shuttle valve 362 are provided with the switching control port 315 and the stroke control port only when the pressure oil needs to be discharged from the switching control port 315. 115 is communicated, and otherwise the communication state between the switching control port 315 and the stroke control port 115 is blocked, so that the control pressure holding mechanism of the present invention is configured.

  According to the second embodiment, the second control valve 300 ′ has a high pressure holding mechanism and a low pressure holding mechanism as in the first embodiment as a control pressure holding mechanism for holding the pressure receiving state of the switching control port. Since it is not necessary to provide a mechanism, the axial dimensions of the small diameter part 331 and the medium diameter part 333 of the spool 330 ′ can be shortened, and the axial dimension of the entire second control valve 300 ′ can be shortened. . Also, omitting the high-pressure holding mechanism and the low-pressure holding mechanism formed by microfabrication is preferable in terms of reducing the manufacturing cost.

[Modification of Second Embodiment]
Next, a modification of the second embodiment of the present invention will be described with reference to FIG.
This modification has a configuration in which the high pressure holding means in the first embodiment is added to the configuration of the second embodiment. That is, the second control valve 300 ″ includes a central passage 339 and a communication hole 340. The configuration of the second control valve 330 ′ is common except that the provided spool 330 ″ is mounted.

  The added high pressure holding means acts to immediately generate a pressure difference generated between the high pressure chamber 312 and the control chamber 313 in a state where the high pressure oil is supplied to the switching control port 315. This is particularly effective when the amount of oil supplied from 225 to the switching control port 315 is not sufficient. As a result, the high pressure holding state in the control chamber 313 can be more reliably performed, so that it is ensured that the long stroke position of the spool 330 ″ is maintained.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the open / close valve 360, the pilot passage 361, and the shuttle valve 362 are omitted from the modification of the second embodiment, and instead, a pilot check valve 370 and a pilot passage 371 are provided. It has a configuration.
That is, the pilot check is performed so that the flow of pressure oil from the stroke control passage 115 to the switching control port 315 is restricted in the stroke control passage 115 and the flow of pressure oil from the switching control port 315 to the stroke control passage 115 is allowed. A valve 370 is provided, and the pilot passage 371 is connected to the valve control passage 226.

  This pilot check valve 370 acts reliably as a low pressure holding means. That is, the pilot check valve 370 restricts the pressure oil in the piston front chamber 101 from flowing into the control chamber 313 via the stroke control port 105 when the spool 330 ″ is in the short stroke position. Since the pilot passage 371 continues to maintain the operating state of the pilot check valve 370 until the first valve 200 is completely operated with the setting, the low pressure state of the control chamber 313 can be reliably maintained.

It should be noted that the hydraulic striking device according to the present invention is not limited to the above-described embodiment or modification, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.
For example, in the hydraulic striking device of the above embodiment, the piston front chamber 101 is always set to high pressure, the piston rear chamber 102 is switched between high pressure and low pressure, and the piston 120 is moved forward and backward (the front chamber always high pressure rear chamber alternating switching method). However, the present invention is not limited to this. For example, the piston rear chamber 102 is always set to high pressure, and the piston front chamber 101 is switched between high pressure and low pressure to move the piston 120 back and forth (the rear chamber always high pressure front chamber). The present invention can be applied to a hydraulic striking device of an alternating switching method) or a method in which the piston 120 is moved back and forth by alternately switching the piston front chamber 101 and the piston rear chamber 102 between high pressure and low pressure (front and rear chamber alternating switching method). it can.

100 Cylinder 101 Piston front chamber 102 Piston rear chamber 103 Front chamber port 104 Rear chamber port 105 Short stroke port (SP)
106 Stroke control port (MP)
107 Long stroke port (LP)
108 Low pressure port 110 High pressure circuit 111 Low pressure circuit 112 Front chamber passage 113 Rear chamber passage 114 Valve control passage (direct connection)
115 Stroke control passage 116 Stroke switching passage 117 Low pressure passage 120 Piston 121 Front large diameter portion 122 Rear large diameter portion 123 Medium diameter portion 124 Small diameter portion 125 Ring groove 200 First control valve 201 Valve 202 Medium diameter portion 203 Large diameter portion 204 Small-diameter portion 205 Oil drain groove 206 Front end surface 207 Rear end surface 208 Front stepped surface 209 Rear stepped surface 210 Communication hole 211 Slit groove 212 Valve chamber 213 Valve front chamber 214 Valve main chamber 215 Valve rear chamber 216 Valve chamber front end surface 217 Valve chamber rear end surface 218 Front low pressure port 219 Reset port 220 Valve control port 221 Rear low pressure port 222 Rear chamber port 223 Front chamber passage 224 Front low pressure passage 225 Reset passage 226 Valve control passage (via spool)
227 Rear low pressure passage 228 Hollow passage 300, 300 ′, 300 ″ Second control valve (stroke control valve)
301 Housing 302 First sleeve 303, 303 ′ Second sleeve 304 Plug 305 Spool chamber 306 Small diameter portion 307 Large diameter portion 308 Medium diameter portion 309 Upper end surface 310 Lower end surface 311 Slit drain groove 312 High pressure chamber 313 Control chamber 314 High pressure port 315 Switching control port 316 Low pressure port 317 Valve communication port 318 Cylinder communication port 319 Drain port 320 High pressure passage 321 Low pressure passage 322 Drain passage 330, 330 ', 330''Spool 331 Small diameter portion 332 Large diameter portion 333 Medium diameter portion 334 Upper stage Attached surface 335 Lower stepped surface 336 Communication groove 337 Drain groove 338 Drain passage 339 Central passage 340 Communication hole 350 Check valve 360 Open / close valve 361 Pilot passage 362 Shuttle valve 370 Pilot check valve 371 Pilot passage 400 Back head 500 Front head 501 Rod F Thrust G Gas P Pump T Tank

Claims (3)

A hydraulic striking device for striking a striking rod by moving a piston back and forth in a cylinder by a stroke selected from one of a short stroke and a long stroke,
The cylinder having the stroke control port provided at a position between the short stroke port, the long stroke port and the two ports as three ports for stroke control;
The piston slidingly fitted inside the cylinder;
A piston front chamber and a piston rear chamber defined between an outer peripheral surface of the piston and an inner peripheral surface of the cylinder and spaced apart in the axial direction;
A first control valve for switching at least one of the piston front chamber and the piston rear chamber to at least one of a high pressure circuit and a low pressure circuit to drive the piston at the selected stroke;
A switching control port whose pressure receiving state changes according to the forward / backward moving position of the piston with respect to the three ports, and a spool positioned at either the long stroke position or the short stroke position according to the pressure receiving state of the switching control port. And a second control valve that selects the stroke of the first control valve according to the position of the spool;
Maintains the pressure receiving state of the switching control port when the spool of the second control valve is in the long stroke position and the pressure receiving state of the switching control port when the spool of the second control valve is in the short stroke position. A control pressure holding mechanism to
A hydraulic striking device comprising:   The control pressure holding mechanism includes high pressure holding means for connecting the switching control port and the high pressure circuit when the spool of the second control valve is in the long stroke position, and the spool of the second control valve is shorted. 2. The hydraulic striking device according to claim 1, further comprising a low-pressure holding unit that connects the switching control port and the low-pressure circuit when in a stroke position. 3.   The control pressure holding mechanism communicates the switching control port with the stroke control port only when the pressure oil needs to be discharged from the switching control port, and otherwise, the switching control port and the stroke control The hydraulic striking device according to claim 1, wherein the hydraulic striking device is an on-off valve that blocks communication with a port.

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