JP7390940B2 - Hydraulic striking device - Google Patents

Description

The present invention relates to hydraulic striking devices such as rock drills and breakers, and particularly relates to a hydraulic striking device equipped with a dry striking prevention mechanism that stops the operation when a piston advances beyond a predetermined striking position. .

In this type of hydraulic striking device, a piston strikes a rod and transmits the impact energy to the object to be crushed. In a hydraulic impact device, generally, crushing by impact is performed continuously in rock excavation work. On the other hand, in splitting operations, when the object to be crushed is crushed by a blow, a "dry strike" occurs in which the piston hits the rod without sufficient contact between the rod and the object to be crushed. .
Dry striking places a large load on the rod and the main body of the hydraulic striking device. For this reason, various so-called "dry-hit prevention mechanisms" (also referred to as "auto-stop mechanisms") have been proposed for the purpose of protecting the hydraulic striking device from impact during dry-hitting.
The dry striking prevention mechanism forcibly stops the operation of the hydraulic striking device when the piston advances a predetermined distance beyond the normal striking position, as the rod advances beyond the normal striking position in the dry striking state. It is something.

The present applicant has proposed a technique shown in FIG. 4 as a hydraulic impact device equipped with a dry strike prevention mechanism. The hydraulic impact device includes a cylinder 500, a piston 520, a first control valve 600, and a second control valve 700. The piston 520 is slidably fitted into the cylinder 500, and the first control valve 600 and the second control valve 700 are provided separately from the cylinder 500.
The piston 520 is a solid cylindrical body, and has two large diameter parts approximately in the center thereof, a front large diameter part 521 and a rear large diameter part 522. A medium diameter part 523 is provided in front of the front large diameter part 521 , a small diameter part 524 is provided behind the rear large diameter part 522 , and a small diameter part 524 is provided between the front large diameter part 521 and the rear large diameter part 522 . An annular groove 525 is provided.

This piston 520 is slidably fitted into the cylinder 500, thereby defining a piston front chamber 501 and a piston rear chamber 502 at the front and rear inside the cylinder 500, respectively. A front chamber port 503 is provided in the piston front chamber 501, and the front chamber port 503 is always connected to a high pressure circuit 508 via a front chamber passage 510.
A rear chamber port 504 is provided in the piston rear chamber 502 . The rear chamber port 504 and the first control valve 600 are connected by a rear chamber passage 511. The piston rear chamber 502 can be alternately communicated with the high pressure circuit 508 and the low pressure circuit 509 by switching the valve 601 of the first control valve 600 back and forth.

The outer diameter of the medium diameter portion 523 is set larger than the outer diameter of the small diameter portion 524. As a result, the pressure receiving area of the piston 120 in the piston front chamber 501 and the piston rear chamber 102, that is, the diameter difference between the front large diameter section 121 and the medium diameter section 123, and the diameter difference between the rear large diameter section 122 and the small diameter section 124 are The piston rear chamber 102 side is larger.
As a result, when the piston rear chamber 502 is connected to high pressure by the operation of the valve 601, the piston 520 moves forward due to the pressure receiving area difference, and when the piston rear chamber 502 is connected to the low pressure by the operation of the valve 601, the piston 520 moves backward. It has become.

In the cylinder 500, a second control valve communication port 505, a first control valve communication port 506, and a low pressure port 507 are arranged in order from the front to the rear between the front chamber port 503 and the rear chamber port 504 in the axial direction. are located at positions separated from each other.
The second control valve communication port 505 is connected to the spool chamber 702 of the second control valve 700, which will be described later, via the second control valve communication passage 513, and the first control valve communication port 506 is connected to the first control valve communication passage 512. The low pressure port 507 is connected to a low pressure circuit 509 via a low pressure passage 515.

In the first control valve 600, a valve plug 630 is installed inside a valve housing 640 provided separately from the cylinder 500 to form a valve chamber 609, and a valve 601 is slidably fitted into the valve chamber 609. . The valve chamber 609 is provided with a valve regulation chamber 610 and a valve control chamber 616 facing each other in the front and rear. Valve regulation chamber 610 is always connected to high pressure circuit 508.

The valve 601 is a hollow cylindrical body, and has an oil drain hole 605 and an oil supply hole 607 spaced apart from each other on its side surface, and is always urged forward by high pressure oil supplied to a valve regulation chamber 610. The valve control chamber 616 is configured to move rearward when high pressure oil is supplied to the valve control chamber 616.
When the valve 601 is at the front end position, the piston rear chamber 502 is communicated and pressure-connected with the low pressure circuit 509 through the oil drain hole 605 . On the other hand, when the valve 601 is at the rear end position, the oil drain hole 605 is blocked and the piston rear chamber 502 is communicated with the high pressure circuit 508 for high pressure connection.

In the second control valve 700 (700'), a spool chamber 702 is formed in the valve housing 640 in a non-coaxial and torsional relationship with the first control valve 600, a sleeve 703 is attached to the spool chamber 702, and a sleeve 703 is mounted inside the sleeve 703. A dry-shot prevention spool 710 is slidably fitted into the spool 710. The spool chamber 702 is closed by a plug 701.
The spool chamber 702 is connected to a high pressure passage 514 branched from the high pressure circuit 508, a valve control passage 620 branched from the first control valve communication passage 512, and a second control valve communication passage 513. Further, a pilot port 704 is connected to the spool chamber 702, and the operation of the second control valve 700 can be controlled by supplying and discharging pressure oil to the pilot port.

By the way, as mentioned above, the piston 520 and the first control valve 600 of the hydraulic impact device are not coaxial with each other, but the axial center CL of the piston 520 and the axial center CL of the first control valve 600 are are set to match in plan view, that is, in a horizontal cross-sectional view, the axes CL of both are set to match in the vertical direction. Furthermore, the piston 520 and the axis CL of the first control valve 600 are arranged at the center in the width direction of the hydraulic impact device (see Patent Document 1).

The basic configuration shown in FIG. 4 is a hydraulic impact device in which the front chamber is always connected to high pressure and the rear chamber is switched between high and low pressure, and a description of its operating mechanism will be omitted.
When the dry firing prevention spool 710 of the second control valve 700 is in the lower position as shown in FIG. 5, the high pressure passage 514 and the second control valve communication passage 513 communicate with each other. Therefore, in a normal impact cycle, the impact is made with a long stroke, and as shown in FIG. When the control valve communication port 506 communicates, the piston rear chamber 502 is connected to high pressure, and the piston 520 stops.

When the dry firing prevention spool 710 of the second control valve 700 is in the upper position, the valve control passage 620 and the second control valve communication passage 513 communicate with each other. Therefore, in a normal striking cycle, even if the piston 520 strikes with a short stroke and advances beyond the normal striking position as shown in FIG. 4, the piston rear chamber 502 is not connected to high pressure, so the piston 520 starts reversing without stopping.
In this way, the hydraulic striking device allows a dry hit when hitting with a short stroke and prevents a dry hit when hitting with a long stroke by switching the dry hitting prevention spool 710 of the second control valve 700. To prevent. This operating mode is called a blank shot prevention mode.

In addition, the second control valve 700' has a mode in which a stroke adjustment spool 720 is installed in the spool chamber 702 in place of the dry stroke prevention spool 710, and according to the second control valve 700', it is possible to adjust whether the stroke is a short stroke or a long stroke. Even if you select , blank hits are allowed. This operating mode is called stroke adjustment mode.

Japanese Patent Application Publication No. 10-80878

As shown in FIG. 5, in this hydraulic impact device, the second control valve 700 is provided on the side of the first control valve 600 in a twisted relationship, that is, their axes do not intersect and are perpendicular to each other. There is. 5, the axial center of the spool chamber 702 is offset from the axial center CL of the first control valve 600 by an interaxial distance L.
The high pressure passage 514 is also offset by an interaxial distance L from the axis CL of the first control valve 600, and the second control valve communication passage 513 is arranged on the side of the spool chamber 702, that is, further outside the high pressure passage 514. It is set up.

In this manner, in the situation where the dry striking prevention mechanism operates in the hydraulic striking device, the path consisting of the high pressure passage 514 - the spool chamber 702 - the second control valve communication passage 513 is connected to the axis CL of the piston 520 of the hydraulic striking device. Since the first control valve 600 is largely offset from the first control valve 600 and is provided with a detour that bypasses the constituent members of the first control valve 600, the hydraulic path becomes long, pressure loss increases, and hydraulic efficiency decreases.
Therefore, the present invention has been made with attention to such problems, and in a hydraulic impact device equipped with a second control valve that switches between a dry striking prevention mode and a stroke adjustment mode, a decrease in hydraulic efficiency is achieved. An object of the present invention is to provide a hydraulic impact device that can suppress the

In order to solve the above problems, a hydraulic impact device according to one aspect of the present invention includes a cylinder, a piston slidably fitted inside the cylinder so as to be movable back and forth, and an outer circumferential surface of the piston and an inner surface of the cylinder. a piston front chamber and a piston rear chamber defined between the peripheral surface and spaced apart from each other in the front and rear of the axial direction; a stroke adjustment mechanism that adjusts the stroke of the piston between a long stroke and a short stroke; a dry-strike prevention mechanism that connects the piston rear chamber to a high-pressure circuit to stop the operation of the piston when the piston advances a predetermined distance beyond the striking position; and a first control valve that controls the forward and backward movement of the piston. and a second control valve that selects a mode of either the stroke adjustment mechanism or the dry striking prevention mechanism, wherein the first control valve is configured to connect the piston to the cylinder. A valve chamber is provided non-coaxially with the axis and substantially parallel to each other, and the valve chamber is provided with at least a high pressure connected to the high pressure circuit in order to obtain the movement necessary for controlling the forward and backward movement of the piston. The passages are connected to valve control passages that communicate with their own valve control ports, and the second control valve is located in the cylinder at a position forward of the first control valve, and the axis of its own spool chamber is aligned with the second control valve. The spool chamber is provided at a position twisted with respect to the axis of the valve chamber of the control valve, and the spool chamber includes the high pressure passage, the valve control passage, and the valve control passage. A second control valve communication passage is connected to each cylinder, and a front chamber port, a second control valve communication port, a first control A valve communication port and a low pressure port are provided in this order, the front chamber port communicates with the high pressure passage via the front chamber passage, and the second control valve communication port communicates with the high pressure passage through the second control valve communication passage. The first control valve communication port communicates with the valve control passage through a first control valve communication passage, and the valve control passage and the high pressure passage communicate with the valve chamber of the second control valve. The front chamber passage and the first control valve communication passage are provided non-coaxially with the axis and substantially parallel to each other, and the front chamber passage and the first control valve communication passage are provided in a direction substantially perpendicular to the axis of the piston and substantially parallel to each other. The spool chamber of the second control valve is located between the front chamber passage and the first control valve communication passage, and is provided approximately parallel to each passage, and between the valve control passage and the high pressure passage. The second control valve communication passage is provided at a position that includes the area and is twisted with each passage, and further, the second control valve communication passage is provided at a position substantially coaxial with the axis of the spool chamber. do.

According to the hydraulic striking device according to one aspect of the present invention, the second control valve has a high pressure passage connected to its own spool chamber, a valve control passage, and a second control valve in order to obtain the operation necessary for mode selection. Since the two control valve communication passages are configured to communicate with each other through the shortest route, pressure loss is small, so it is possible to suppress a decrease in hydraulic efficiency.
Here, when this type of hydraulic impact device is provided with an accumulator, it is generally arranged on the piston front chamber 501 side, that is, in front of the first control valve 600, as in the above-mentioned conventional hydraulic impact device. (not shown).
However, as described above, the second control valve 700 is disposed on the side of the first control valve 600, so when the first control valve 600 is driven by the control pressure via the second control valve 700, The impact mechanism may become unstable due to the fact that it becomes less susceptible to the pressure fluctuation buffering effect of the accumulator.

In contrast, in the hydraulic impact device according to one aspect of the present invention, the front chamber passage is formed to extend beyond the node with the high pressure passage, and the front chamber passage is located at a position on the extension line. An accumulator may be provided to communicate with the.
With this configuration, the front chamber passage is extended beyond the node with the high pressure passage, and the accumulator is provided on the extended line, so the second control valve has a buffering effect against pressure fluctuations caused by the accumulator. Since it is fully exerted, it is suitable for stabilizing the operation of the striking mechanism.

Further, in the conventional hydraulic impact device described above, although one end of the second control valve 700 is closed by the plug 701, the plug 701 itself is exposed on the surface of the valve housing 640, so that dust etc. cannot enter. There is room for improvement.
In contrast, in the hydraulic impact device according to one aspect of the present invention, one end of the spool chamber of the second control valve is opened at a position where the mounting surface of the accumulator is covered with the accumulator mounted. It can be configured as follows.
With this configuration, one end of the valve chamber of the second control valve opens to the mounting surface of the accumulator, so that the spool chamber of the second control valve is closed by the accumulator during normal operation. Therefore, it is suitable for providing a configuration in which the intrusion of dust and the like is extremely reduced.

As described above, according to the present invention, a decrease in hydraulic efficiency can be suppressed in a hydraulic impact device equipped with a second control valve that switches between the dry striking prevention mode and the stroke adjustment mode.

1 is a schematic cross-sectional view of a hydraulic impact device according to an embodiment of the present invention, and the figure shows a cross section along the axis of a piston. FIG. 2 is a cross-sectional view taken along the line XX in FIG. 1, showing a state in which the idle hitting prevention mode is set. FIG. 2 is a sectional view taken along the line XX in FIG. 1, showing a state in which the stroke adjustment mode is set ((a) is a short stroke, (b) is a long stroke). FIG. 2 is a schematic cross-sectional view showing a conventional hydraulic impact device. They are a plan view (a) of a first control valve of a conventional hydraulic impact device and a cross-sectional view (b) thereof taken along line AA.

Hereinafter, a first embodiment of the present invention will be described with appropriate reference to the drawings. Note that the drawings are schematic. Therefore, it should be noted that the relationships, ratios, etc. between thickness and planar dimensions are different from those in reality, and the drawings also include portions where the relationships and ratios of dimensions are different.
In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention. etc., are not limited to the embodiments described below.

As shown in FIG. 1, this embodiment of the hydraulic impact device includes a cylinder 100 and a piston 120, and a first control valve 200 and a second control valve 300 (300') are built in the cylinder 100. It is being A valve 201 is slidably fitted inside the first control valve 200, and a dry firing prevention spool 310 and a stroke adjustment spool 320 are selectively installed inside the second control valve 300 (300'). It looks like this.
A back head 400 is attached to the rear of the cylinder 100. The back head 400 is filled with high pressure back head gas G. Further, a front head 401 is attached to the front part of the cylinder 100. A rod 402 is slidably fitted inside the front head 401 .

The piston 120 is a solid cylindrical body, and has two large diameter portions approximately in the center thereof, a front large diameter portion 121 and a rear large diameter portion 122. A medium diameter part 123 is provided in front of the front large diameter part 121 , a small diameter part 124 is provided behind the rear large diameter part 122 , and a small diameter part 124 is provided between the front large diameter part 121 and the rear large diameter part 122 . An annular groove 125 is provided.
The piston 120 is slidably fitted into the cylinder 100, thereby defining a piston front chamber 101 and a piston rear chamber 102 at the front and rear inside the cylinder 100, respectively. A front chamber port 103 is provided in the piston front chamber 101, and the front chamber port 103 is constantly connected to the high pressure circuit 108 via the front chamber passage 110, the node 110a, the high pressure passage 114, and the hollow passage 222.

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 111. The piston rear chamber 102 can be alternately communicated with the high pressure circuit 108 and the low pressure circuit 109 by switching the valve 201 of the first control valve 200 back and forth.
The outer diameter of the medium diameter portion 123 is set larger than the outer diameter of the small diameter portion 124. As a result, 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 section 121 and the medium diameter section 123, and the diameter difference between the rear large diameter section 122 and the small diameter section 124 are The piston rear chamber 102 side is larger.
As a result, when the piston rear chamber 102 is connected to a 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 a low pressure by the operation of the valve 201, the piston 120 moves backward. It has become.

In the cylinder 100, a second control valve communication port 105, a first control valve communication port 106, and a low pressure port 107 are arranged in order from the front to the rear between the front chamber port 103 and the rear chamber port 104 in the axial direction. are located at positions separated from each other.
The second control valve communication port 105 is connected to the spool chamber 302 of the second control valve 300 via the second control valve communication passage 113, and the first control valve communication port 106 is connected to the spool chamber 302 of the second control valve 300 via the first control valve communication passage 112. The valve control passage 220 is connected, and the low pressure port 107 is connected to the low pressure circuit 109 via the low pressure passage 115.
An accumulator mounting surface 116 is formed on the upper surface of the cylinder 100, and an accumulator 130 is removably mounted thereon with a bolt (not shown). The accumulator 130 is connected to the high pressure passage 114 via the front chamber passage 110 and the node 100a.

In the first control valve 200, a valve chamber 209 is formed inside the cylinder 100, non-coaxially and parallel to the piston 120, and the valve 201 is slidably fitted into the valve chamber 209. The valve chamber 209 includes, in order from the front to the rear, a medium-diameter front valve chamber 210, a large-diameter valve main chamber 211, and a small-diameter valve rear chamber 212. Near the axis of the valve chamber 209, a high pressure passage 114 is connected to the valve front chamber 210 side, and a high pressure circuit 108 is connected to the valve rear chamber 212 side.

The main valve chamber 211 is provided with a front low pressure port 215 and a valve control port 216 in order from the front to the rear, and the rear valve chamber 212 is provided with a rear low pressure port 217 and a rear chamber port 218.
The front low pressure port 215 is connected to the low pressure circuit 109 via the front low pressure passage 219, and the rear low pressure port 217 is connected to the low pressure circuit 109 via the rear low pressure passage 221. The valve control port 216 is connected to the first control valve communication port 106 via the valve control passage 220 and the first control valve communication passage 112. The rear chamber port 218 is connected to the rear chamber port 104 via the rear chamber passage 111.

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 222 inside the cylinder forms a high pressure path. The valve 201 is provided with an annular oil drain groove 205 on the outer circumferential surface of the small diameter portion 204 at approximately the center thereof for switching the piston rear chamber 102 between high pressure and low pressure.
The valve 201 is always biased 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 216, the rear stepped surface of the large diameter portion 203 The pressure receiving area of 208 is added and it moves forward.

When the valve 201 is at the rear end position, that is, when the rear end surface 207 is in contact with the rear end surface 214 of the valve chamber, the rear chamber port 218 is connected to the rear low pressure port 217 and the rear low pressure passage 221 by the oil drain groove 205. Since the piston rear chamber 102 is connected to the low pressure circuit 109, the piston rear chamber 102 is connected to the low pressure circuit 109.
On the other hand, when the valve 201 is at the front end position, that is, when the front end surface 206 is in contact with the front end surface 213 of the valve chamber, the communication between the rear chamber port 218 and the rear low pressure port 217 is cut off. The piston rear chamber 102 is connected to the valve rear chamber 212 via the gap between the valve chamber rear end surface 214 and the hollow passage 222, which is connected to the valve chamber 212 under high pressure.

The second control valve 300 (300') has a spool chamber 302 formed near the top surface of the cylinder 100 in a non-coaxial and torsional relationship with the piston 120 and the first control valve 200. By selectively installing the stroke adjustment spool 320 and the stroke adjustment spool 320, it is possible to switch between the dry hitting prevention mode and the stroke adjustment mode.
The spool chamber 302 is provided with a high pressure port 306 and a stroke adjustment port 307, which will be described later.The high pressure port 306 is connected to the high pressure passage 114, and the stroke adjustment port 307 is connected to the valve control passage 220.

FIG. 2 is the upper right quarter of the cross-sectional view taken along the XX line in FIG. That is, in this state, the hydraulic impact device operates in the dry-hit prevention mode.
FIG. 2 shows a through bolt hole 117 for inserting a known through bolt (not shown) that fastens the cylinder 100, back head 400, and front head 401. Furthermore, although FIG. 2 shows the positions and dimensions of each element with some accuracy, it shows that the second control valve 300 is not actually arranged in the same cross section as the piston 120 as shown in FIG. can be read.

The spool chamber 302 has a spool chamber large diameter section 303, a spool chamber medium diameter section 304, and a spool chamber small diameter section 305 in order from above to below. The spool chamber large diameter section 303 side of the spool chamber 302 opens to the accumulator mounting surface 116, and the second control valve communication passage 113 is coaxially connected to the axis on the small diameter section 305 side. A plug 301 is attached to the upper end of the large diameter portion 303 of the spool chamber, thereby holding the spool 310 to prevent blank firing and sealing the spool chamber 302.

The dry-shot prevention spool 310 is a solid cylindrical body consisting of a spool medium diameter portion 311 and a spool small diameter portion 312 in order from the top to the bottom. The spool chamber medium diameter section 304 and the spool small diameter section 312 cooperate to form a high pressure port 306, and the spool chamber large diameter section 303 and the spool medium diameter section 311 cooperate to form a stroke adjustment port 307. A communication passage 313 connecting the high pressure port 306 and the second control valve communication passage 113 is provided in the lower half of the dry firing prevention spool 310.

The operation and effects when operating the hydraulic striking device equipped with the second control valve 300 in the dry striking prevention mode are the same as in other projects (for example, Japanese Patent Application No. 2019-135559), so explanations will be omitted.
Here, the positional relationships of various hydraulic passages surrounding the second control valve 300 will be summarized.
The piston 120, the high pressure passage 114, and the valve control passage 220 are formed non-coaxially and substantially parallel to each other. The second control valve 300 is formed in a non-coaxial and twisted relationship with the piston 120, the high pressure passage 114, and the valve control passage 220, respectively.

The high pressure passage 114 is disposed at the center of the cylinder 100 in the width direction (the left-right direction in FIG. 2), and the second control valve 300 is offset from this by an interaxial distance L1, and the valve control passage 220 is provided offset from the second control valve 300 by an interaxial distance L2.
Assuming that the inner diameter of the high pressure passage 114 is ΦD1, the inner diameter of the valve control passage 220 is ΦD2, the inner diameter of the spool chamber medium diameter section 304 is Φd1, and the inner diameter of the spool chamber large diameter section 303 is Φd2,
L1<[ΦD1+Φd1]/2...Formula 1
L2<[ΦD2+Φd2]/2...Formula 2
The relationship is

That is, the inner wall of the high pressure passage 114 and the inner wall of the high pressure port 306 overlap and communicate directly, and similarly, the inner wall of the valve control passage 220 and the inner wall of the stroke adjustment port 307 overlap and communicate directly. The amount of overlap for each is determined appropriately according to the passing flow rate.
In this way, since there is no connection passage for communication between the connection point between the high pressure passage 114 and the high pressure port 306 and the connection point between the valve control passage 220 and the stroke adjustment port 307, the configuration of the hydraulic path is very simple. And it is the shortest distance. Further, according to FIG. 2, it can be seen that the second control valve communication passage 113 is provided coaxially with the spool chamber 302, and is connected to the second control valve communication port 105 over a very short distance.

Therefore, the various hydraulic passages surrounding the second control valve 300 are very simple and communicate with each other at the shortest distance depending on their positional relationships, so that in the hydraulic impact device of the present invention, the second control valve 3000 operates. It has low pressure loss, good hydraulic efficiency, and excellent responsiveness in situations.
Incidentally, in the conventional hydraulic impact device, if the inner diameter of the valve control chamber 616 is ΦD616 and the inner diameter of the spool chamber 702 is Φd702, the following relationship holds true.
L>[ΦD616+Φd702]/2...Formula 3

Next, the relationship between the second control valve 300 and the accumulator 130 will be considered.
As shown in FIG. 1, the distance between the axes of the accumulator 130 and the second control valve 300 is the same as the distance between the axes of the front chamber passage 110 and the second control valve communication passage 113, and they are very close to each other.
Furthermore, it can be seen that the node 100a between the front chamber passage 110 and the high pressure passage 114 is on the back side of the paper in FIG. 2 and directly to the side of the high pressure port 306.
Therefore, the hydraulic path that constitutes the dry firing prevention mechanism from the high pressure passage 114 to the high pressure port 306 to the communication passage 113 to the second control valve communication port 105, and the hydraulic pressure that constitutes the accumulator 130 to the front chamber passage 110 to the node 100a. The paths are connected by the shortest distance, and the buffering effect of the pressure oil by the accumulator 130 is sufficiently exerted in these hydraulic paths, so that the operation of the hydraulic striking device in the dry striking prevention mode is stabilized.

The upper part of the spool chamber 302 of the second control valve 300 is open to the accumulator mounting surface 116, and after the dry firing prevention spool 310 is installed in the spool chamber 302, the spool chamber 302 is sealed by the plug 301. Since the accumulator 130 is mounted on the accumulator mounting surface 116 when the hydraulic impact device is used, the spool chamber 302 is doubly isolated from the outside air, so there is no fear of foreign matter entering.
Here, comparing the present invention and the prior art again, although the second control valve 300 of the present embodiment is provided offset from the axis of the piston 120 in common with the prior art, the present embodiment In this case, the second control valve 300 is disposed approximately near the axis, whereas in the prior art, the second control valve 700 is disposed on the side of the first control valve 600, as shown in FIG. It is set up.

Therefore, it is clear that the layouts of the present invention and the prior art have a large offset amount and a significant difference in the length of the hydraulic path, which greatly affects the pressure loss. Furthermore, the layout of the second control valve 300 of the present embodiment connects two hydraulic devices without using unnecessary communication means, whereas the second control valve 700 of the prior art is disposed in the bypassed path, so it is clear that the difference in pressure drop between the two is large in this respect as well.

FIG. 3 is the upper right quarter of the XX-line cross-sectional view of FIG. 1, and shows a state in which the stroke adjustment spool 320 is attached to the second control valve 300'. That is, in this state, the hydraulic impact device operates in the stroke adjustment mode. The diagram on the right side of FIG. 3 is set to a long stroke, and the diagram on the left side is set to a short stroke.
The basic configuration of FIG. 3 is the same as that of FIG. 2, so only the differences will be explained.
A stroke adjustment spool 320 is attached to the second control valve 300'. The stroke adjustment spool 320 is a solid cylindrical body consisting of a medium diameter portion 321 and a small diameter portion 322 in order from the top to the bottom. A first communication passage 323 is provided at the axis of the stroke adjustment spool 320, a tap 324 is provided above the first communication passage 323, and a second communication passage 325 is provided above the tap 324.

When the stroke adjustment spool 320 is installed in the spool chamber 302, the second control valve communication port 105 is connected to the second control valve communication passage 113 - the first communication passage 323 - the tap 324 - the second communication passage 325 - the stroke adjustment spool port 307 - the valve. The short stroke path leading to the control passage 220 is simple and communicates over the shortest distance.
Therefore, the hydraulic impact device of the present invention has less pressure loss, good hydraulic efficiency, and excellent responsiveness when the second control valve 300' operates. Note that when the plug 326 is attached to the tap 324, the short stroke path is cut off, so the second control valve 300' stops operating and the hydraulic impact device operates with a long stroke.

It should be noted that the hydraulic impact device according to the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.
For example, the stroke adjustment spool 320 of the second control valve 300' is configured with a short stroke spool with a communication path and a long stroke spool without a communication path, and the stroke can be changed by replacing these two spools. Also good.
In addition, it goes without saying that the words used in the description of the embodiments expressing postures and positional relationships such as coaxial, parallel, twisted, etc. allow for some errors; for example, the high pressure passage 114 is In order to shorten the distance of the chamber port 103, it is also possible to configure the chamber port 103 by tilting it forward (downward to the left in FIG. 1).

100 (500) Cylinder 101 (501) Piston front chamber 102 (502) Piston rear chamber 103 (503) Front chamber port 104 (504) Rear chamber port 105 (505) Second control valve communication port 106 (506) First control Valve communication port 107 (507) Low pressure port 108 (508) High pressure circuit 109 (509) Low pressure circuit 110 (510) Front chamber passage 110a Node point 111 (511) Rear chamber passage 112 (512) First control valve communication passage 113 ( 513) Second control valve communication passage 114 (514) High pressure passage 115 (515) Low pressure passage 116 Accumulator mounting surface 117 Through bolt hole 120 (520) Piston 121 (521) Front large diameter section 122 (522) Rear large diameter section 123 (523) Medium diameter section 124 (524) Small diameter section 125 (525) Annular groove 130 Accumulator 200 (600) First control valve 201 (601) Valve 202 Medium diameter section 203 Large diameter section 204 Small diameter section 205 (605) Oil drain groove (oil drain hole)
206 Front end surface 207 (607) Rear end surface (oil supply hole)
208 Stepped surface 209 (609) Valve chamber 210 (610) Valve front chamber (valve regulation chamber)
211 Valve main chamber 212 Valve rear chamber 213 Valve chamber front end surface 214 Valve chamber rear end surface 215 Front low pressure port 216 (616) Valve control port (valve control chamber)
217 Rear low pressure port 218 Rear chamber port 219 Front low pressure passage 220 (620) Valve control passage 221 Rear low pressure passage 222 Hollow passage 300, 300' (700, 700') Second control valve 301 (701) Plug 302 (702) ) Spool chamber 303 Spool chamber large diameter section 304 Spool chamber medium diameter section 305 Spool chamber small diameter section 306 High pressure port 307 Stroke adjustment port 310 (710) Drop-shot prevention spool 311 Medium diameter section 312 Small diameter section 313 Communication passage 320 (720) Stroke Adjustment spool 321 Medium diameter section 322 Small diameter section 323 First communication passage 324 Tap 325 Second communication passage 326 Plug 400 Back head 401 Front head 402 Rod 630 Valve plug 640 Valve housing 703 Sleeve 704 Pilot ports L1, L2 (L) Between shafts Distance ΦD1, ΦD2 Passage diameter Φd1, Φd2 Spool interior diameter CL Axis F Thrust G Gas P Pump T Tank

Claims (3)

a cylinder; a piston slidably fitted into the cylinder so as to be movable back and forth; and a piston front defined between an outer circumferential surface of the piston and an inner circumferential surface of the cylinder and spaced apart from each other in the axial direction. a stroke adjustment mechanism that adjusts the stroke of the piston between a long stroke and a short stroke; and a stroke adjustment mechanism that connects the piston rear chamber to a high pressure circuit when the piston advances a predetermined distance beyond a striking position. A dry firing prevention mechanism that is connected to stop the operation of the piston, a first control valve that controls forward and backward movement of the piston, and a mode of one of the stroke adjustment mechanism and the dry firing prevention mechanism is selected. A hydraulic striking device comprising a second control valve,
The first control valve has its own valve chamber provided in the cylinder non-coaxially with the axis of the piston and substantially parallel to each other, and the valve chamber has an operation necessary for controlling the forward and backward movement of the piston. at least a high pressure passage communicating with the high pressure circuit and a valve control passage communicating with its own valve control port,
The second control valve has a spool chamber provided in the cylinder at a position forward of the first control valve and at a position where the axis of the second control valve is twisted with respect to the axis of the valve chamber of the first control valve. and the high pressure passage, the valve control passage, and the second control valve communication passage are respectively connected to the spool chamber in order to obtain the operation necessary for selecting the mode,
The cylinder is provided with a front chamber port, a second control valve communication port, a first control valve communication port, and a low pressure port in this order from the front to the rear between the piston front chamber and the piston rear chamber. and the front chamber port communicates with the high pressure passage via the front chamber passage, and the second control valve communication port communicates with the valve chamber of the second control valve via the second control valve communication passage, the first control valve communication port communicates with the valve control passage via a first control valve communication passage;
The valve control passage and the high pressure passage are provided non-coaxially with the axis of the piston and substantially parallel to each other, and the front chamber passage and the first control valve communication passage are provided in a direction substantially orthogonal to the axis of the piston. and are provided approximately parallel to each other,
The spool chamber of the second control valve is located between the front chamber passage and the first control valve communication passage, and is provided approximately parallel to each passage, and is located between the valve control passage and the high pressure passage. The second control valve communication passage is provided at a position including a region between the two and twisted with each passage, and further, the second control valve communication passage is provided at a position substantially coaxial with the axis of the spool chamber. Features a hydraulic striking device. The front chamber passage is formed to extend beyond a node with the high pressure passage, and an accumulator is provided so as to communicate with the front chamber passage at a position on the extension line. Hydraulic striking device. 3. The hydraulic striking device according to claim 2, wherein one end of the spool chamber of the second control valve opens at a position where the mounting surface of the accumulator is covered with the accumulator mounted thereon.

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