JP2019074140A - Flow rate control valve for pneumatic boring machine - Google Patents

Abstract

To provide a flow rate control valve for pneumatic boring machine capable of controlling two stages of flow rate adjustment and stoppage of supply of compressed air with a simple constitution.SOLUTION: A flow rate control valve 200 is arranged on one compressed air supply passage 103 between a pneumatic boring machine 101 and a compressor 102 and is provided with a valve main body 201 having a large diameter valve chamber 211 which stores a large diameter spool 216 slidably and a small diameter valve chamber 221 which stores a small diameter spool 226 slidably and a control part 240 which supplies a pilot oil pressure for actuating a large diameter spool 216 and a small diameter spool 226 of the valve main body 201. The large diameter valve chamber 211 has large-diameter communication holes 213, 214 which are opened and closed by forward and backward movement of the large diameter spool 216 and connect and disconnect a compressed air supply passage 103, and a small diameter valve chamber 221 has small diameter communication holes 223, 224 which are opened and closed by forward and backward movements of the small diameter spool 226 and connect and disconnect the compressed air supply passage 103.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flow control valve used in a pneumatic drilling machine such as a down-the-hole drill.

  The down-the-hole drill uses compressed air supplied from a compressor as a working fluid. That is, in the down-the-hole drill, the striking mechanism is operated by the compressed air supplied from the compressor, and the rock generated by the striking mechanism is crushed. The compressed air supplied from the compressor is also used as flushing air for discharging the cut powder generated in the holes to the outside of the holes.

  The technique of patent document 1 is proposed as an example of control of the compressor which supplies compressed air to a down the hole drill. In the document, an on-off valve mechanism for opening and closing a path is provided in the middle of the compressed air supply path from the compressor to the down-the-hole hammer. In the same document, a compressor control device which drives an on-off valve by an air cylinder operated by compressed air supplied from a compressor as an on-off valve mechanism and on / off controls the operation of the air cylinder by a control signal of a remote control box. It is disclosed.

  Here, in general, when drilling holes with a blast hole drill such as a down-the-hole drill or a top hammer type crawler drill, at the start of the operation, "cut holes" are made to prevent bending and then to a predetermined depth. Make a "book hole" until it reaches. The drilling is done with the most efficient drilling pressure. On the other hand, the hole cutting operation is a drilling operation performed by suppressing the operating pressure. Therefore, a compressor that supplies compressed air as a working fluid to the blast hole drill needs to be controlled to supply and stop the compressed air and to adjust the supply flow rate in two stages.

  On the other hand, since the compressor control device described in Patent Document 1 can only control on / off of compressed air, in the conventional pneumatic drilling machine, the compressed air supply path from the compressor is a path with a large flow rate and a flow rate. Branch into two systems of small routes (ie large diameter piping and small diameter piping), install the on-off valve mechanism as described above on each route, and then connect to the down-the-hole hammer to operate the down-the-hole hammer. It realizes the switching of the operation of the stop, the drilling hole and the drilling hole.

Japanese Utility Model Application Publication No. 7-10501

  However, in the conventional pneumatic drilling machine, since two compressed air supply paths are provided, there is a problem that the apparatus becomes large and the cost is increased, and further, there is a problem that the maintainability is also poor. In addition, although it is theoretically possible to adopt a butterfly valve capable of controlling the amount of opening and closing as a flow rate adjustment mechanism, the amount of compressed air supplied to the down-the-hole hammer is enormous, and has strength corresponding to this. Butterfly valves are very expensive. In addition, since the butterfly valve also needs control of the rotation angle, it is not preferable because the cost is increased.

  Therefore, the present invention has been made focusing on such problems, and it is possible to control the flow adjustment of two stages of the compressed air and the stop of the supply with a simple configuration, and the flow control for the pneumatic drilling machine It is an issue to provide a valve.

  In order to solve the above problems, a flow control valve for a pneumatic drilling machine according to one aspect of the present invention is used in a pneumatic drilling machine, and one compressed air supply path between the pneumatic drilling machine and a compressor. A valve body having a large diameter valve chamber slidably accommodating the large diameter spool and a small diameter valve chamber slidably accommodating the small diameter spool; And a control unit for supplying a pilot hydraulic pressure for operating the large diameter spool and the small diameter spool, and the large diameter valve chamber is opened and closed by forward and backward movement of the large diameter spool to connect and disconnect the compressed air supply path. The small-diameter valve chamber has a small-diameter communication hole that opens and closes by forward and backward movement of the small-diameter spool to connect and disconnect the compressed air supply path.

  According to the flow control valve for a pneumatic drilling machine according to one aspect of the present invention, the large diameter spool and the small diameter spool are independently operated independently by the pilot hydraulic pressure supplied from the control unit, and the large diameter spool and the small diameter spool Since the large diameter communication hole and the small diameter communication hole are opened and closed by the operation of the above-described embodiment, it is possible to selectively perform the stop of the compressed air, the large flow supply, and the small flow supply to the pneumatic drilling machine.

  That is, when both the large diameter communication hole and the small diameter communication hole are closed, the compressed air supply path is shut off and the pneumatic drilling machine does not operate, and when the large diameter communication hole is closed and the small diameter communication hole is opened, the compressed air supply path Since a small amount of compressed air flows through the valve, it is possible to cut off the opening with a pneumatic drilling machine. Furthermore, when the large diameter communication hole is opened and the small diameter communication hole is closed, a large amount of compressed air is supplied to the compressed air supply path. Because of the circulation, the drilling operation of the pneumatic drilling machine is possible.

  And the flow control valve for pneumatic drilling machine according to one aspect of the present invention does not need to provide two systems of large diameter / small diameter compressed air supply piping like the conventional down-the-hole drill, and the valve body The device is compact because it incorporates a flow rate adjustment mechanism that controls the flow rate by opening and closing the large and small communication holes in combination with the forward and reverse movement of the spool. In addition, since this flow rate adjustment mechanism is a method of controlling the flow rate by opening and closing the large and small communication holes by a combination of the large and small spool backward and forward movement independently moving independently, the flow rate is controlled by the rotation angle of the butterfly valve The configuration can be simplified compared to the

  As described above, according to the present invention, it is possible to provide a flow control valve for a pneumatic drilling machine capable of controlling two-stage flow adjustment of compressed air and stop of supply with a simple configuration.

It is a down the hole drill provided with the flow control valve for pneumatic drilling machines of a first embodiment of the present invention. It is a circuit diagram of a flow control valve of a first embodiment. It is three views of the flow control valve of a first embodiment, and the figure (a) is the top view, (b) is a front view, (c) is a right side view. It is the sectional view on the AA line of FIG. 3 in the flow control valve of a first embodiment. It is a schematic diagram explaining the operation | movement (when stopping supply of compressed air) of the flow control valve of 1st embodiment, the figure (a) shows the figure corresponding to FIG. 4, (b) shows in FIG. The corresponding figure is shown. It is a schematic diagram explaining the operation | movement (when supplying compressed air by small flow volume) of the flow control valve of 1st embodiment, the figure (a) shows the figure corresponding to FIG. 4, (b) shows FIG. Shows a diagram corresponding to It is a schematic diagram explaining the operation | movement (when supplying compressed air by large flow volume) of the flow control valve of 1st embodiment, the figure (a) shows the figure corresponding to FIG. 4, (b) shows FIG. Shows a diagram corresponding to It is a circuit diagram of the modification of a first embodiment. It is the circuit diagram (a) of the flow control valve for pneumatic drilling machines of 2nd embodiment of this invention, and principal part explanatory drawing (b). It is a circuit diagram of a modification of a second embodiment. It is a circuit diagram of the flow control valve for pneumatic drilling machines of a third embodiment of the present invention. It is a circuit diagram of a modification of a third embodiment.

  Hereinafter, embodiments of the present invention and modifications thereof will be described with reference to the drawings as appropriate. The drawings are schematic. Therefore, it should be noted that the relationship between the thickness and the plane dimension, the ratio, etc. is different from the actual one, and some parts have different dimensional relationships and ratios among the drawings. In addition, the embodiments and modifications described below illustrate apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention includes materials, shapes, and the like of components. The structure, arrangement, and the like are not specified in the following embodiments or modifications.

First Embodiment
First, a flow control valve for a pneumatic drilling machine according to a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, this down-the-hole drill 100 is provided with a down-the-hole hammer 101 and a compressor 102 on a traveling carriage, and has other known configurations such as a boom, a mast, an engine, and a cabin. The down-the-hole hammer 101 is connected to the compressor 102 via one compressed air supply line 103 shown in FIG.

  As shown in FIG. 2, a flow control valve 200 is provided at an appropriate position between the upstream pipeline 103 a and the downstream pipeline 103 b of the compressed air supply pipeline 103. As shown in FIG. 3, the flow control valve 200 includes a valve block 201 and a solenoid valve 240 attached to one side surface of the valve block 201. The valve block 201 corresponds to the "valve main body" described in the means for solving the above problem, and the solenoid valve 250 corresponds to the "control unit" described in the means for solving the above problem.

The valve block 201 is, as shown in FIG. 3, a rectangular main block 202, a diverting block 203 mounted on the back side of the main block 202, and a merging block 205 mounted on the right side of the main block 202. And.
As shown in cross section in FIG. 4, the main block 202 connects the front chamber 215 f of the large diameter valve chamber 211 and the rear chamber 225 r of the small diameter valve chamber 221, which will be described later, with the discharge port B of the solenoid valve 240. A pilot passage 207 (see FIG. 2) is provided.
In the main block 202, as shown in the figure, a second pilot passage connecting the rear chamber 215r of the large diameter valve chamber 211 and the front chamber 225f of the small diameter valve chamber 221 and the discharge port A of the solenoid valve 240. 208 (see FIG. 2) are provided.

Further, as shown in the figure, the main block 202 is provided with a large flow valve mechanism 210 and a small flow valve mechanism 220.
The large flow rate valve mechanism 210 is configured by slidably mounting a large diameter spool 216 in the large diameter valve chamber 211 at the lower side of the figure. The large diameter valve chamber 211 has a seal chamber 212 on the right side in the figure and a drive chamber 215 on the left side in the figure larger than the seal chamber 212. In the seal chamber 212, a concave truncated cone-shaped seat surface 212a provided at an end portion, and a cylindrical enlarged diameter portion 212b constituted by an inner peripheral wall surface are formed. A circular large diameter communication hole (upstream) 213 opens in the side wall surface of the enlarged diameter portion 212 b in a direction perpendicular to the axis of the large diameter valve chamber 211, and the seat surface 212 a A large diameter communication hole (downstream) 214 is opened coaxially and continuously.

The large diameter spool 216 has a seal portion 217 corresponding to the seal chamber 212 and a drive portion 218 corresponding to the drive chamber 215 coaxially. A convex truncated cone shaped seat surface 217 a corresponding to the seat surface 212 a is formed at the tip of the seal portion 217, and a circular boss shaped protrusion 218 a is coaxially formed at the rear end of the drive portion 218.
The drive chamber 215 is defined by the drive unit 218 into front and rear front chambers 215f and 215r in the axial direction. The pilot hydraulic pressure from the solenoid valve 240 is supplied to and discharged from the front chamber 215f and the rear chamber 215r, respectively, via the first pilot passage 207 and the second pilot passage 208 described above (see FIG. 2). .

  Here, the pressure receiving area of the drive portion 218 in the front chamber 215 f corresponds to the difference between the inner diameter of the drive chamber 215 and the inner diameter of the seal chamber 212. On the other hand, the pressure receiving area of the drive portion 218 in the rear chamber 215 r corresponds to the entire inner diameter of the drive chamber 215. Further, compressed air is supplied to the seal chamber 212, and the pressure receiving area of the seal portion 217 in the seal chamber 212 corresponds to the entire inner diameter of the seal portion 212.

Now, assuming that the pressure receiving area of the rear chamber 215r is Sr1, the pressure receiving area of the front chamber 215f is Sf1, the pressure receiving area of the seal chamber 212 is Ss1, the pilot hydraulic pressure is Pp, and the compressed air pressure is Pa, the large flow valve mechanism 210 The dimensions and pressure of each part are set so that the following (Expression 1) is obtained.
Sr1 × Pp> (Sf1 × Pp + Ss1 × Pa) (Equation 1)

As shown in FIG. 4, the small flow rate valve mechanism 220 is configured by slidably mounting a small diameter spool 226 in the small diameter valve chamber 221 in the upper part of the drawing. The small diameter valve chamber 221 has a seal chamber 222 on the right side in the figure and a drive chamber 225 on the left side in the figure larger than the seal chamber 222.
In the seal chamber 222, a concave truncated cone-shaped seat surface 222a provided at an end portion, and a cylindrical enlarged diameter portion 222b constituted by an inner peripheral wall surface are formed. A circular small diameter communication hole (upstream) 223 is opened in the side wall surface of the enlarged diameter portion 222b in a direction perpendicular to the axis of the small diameter valve chamber 221, and the seat surface 222a is coaxial and continuous with the small diameter valve chamber 221 The small diameter communication hole (downstream) 224 is open.

The small diameter spool 226 coaxially has a seal portion 227 corresponding to the seal chamber 222 and a drive portion 228 corresponding to the drive chamber 225. A convex truncated cone-shaped seat surface 227a corresponding to the seat surface 222a is formed at the tip of the seal portion 227, and a cylindrical protrusion 228a is coaxially formed at the rear end of the drive portion 228.
The drive chamber 225 is defined by the drive portion 228 into axially front and rear front chambers 225f and rear chambers 225r. The pilot hydraulic pressure from the solenoid valve 240 is supplied and discharged to the front chamber 225 f and the rear chamber 225 r through the first pilot passage 207 and the second pilot passage 208, respectively (see FIG. 2).

  Here, the pressure receiving area of the drive portion 228 in the front chamber 225 f corresponds to the difference between the inner diameter of the drive chamber 225 and the inner diameter of the seal chamber 222. On the other hand, the pressure receiving area of the drive portion 228 in the rear chamber 225 r corresponds to the entire inner diameter of the drive chamber 225. Further, compressed air is supplied to the seal chamber 222, and the pressure receiving area of the seal portion 227 in the seal chamber 222 corresponds to the entire inner diameter of the seal chamber 222.

Now, assuming that the pressure receiving area of the rear chamber 225r is Sr2, the pressure receiving area of the front chamber 225f is Sf2, the pressure receiving area of the seal chamber 222 is Ss2, the pilot hydraulic pressure is Pp, and the compressed air pressure is Pa, the small flow valve mechanism 220 The dimensions and pressure of each part are set so that the following (Equation 2) is obtained.
Sr2 × Pp> (Sf2 × Pp + Ss2 × Pa) (Equation 2)

  In the main block 202, a cover (large) 230 is provided on the side face on the rear end side where the drive chamber 215 of the large diameter valve chamber 211 opens. A fixed cap 231 is provided on the inner side of the cover (large) 230 coaxially with the drive chamber 215, and the drive chamber 215 is closed by the fixed cap 231. Further, in the cover (large) 230, a mounting hole 232 is provided coaxially with the driving chamber 225 at a position facing the driving chamber 225 of the small flow rate valve mechanism 220, and a stroke adjusting means 234 described later is provided in the mounting hole 232. It is inserted.

  A cover (small) 233 is provided on the side of the small diameter valve chamber 221 on the side where the drive chamber 225 is opened. The cover (small) 233 is mounted at a position facing the drive chamber 225 and the mounting hole 232, and the stroke adjustment means 234 is mounted. The stroke adjusting means 234 has a moving cap 234 a and an adjusting screw 234 b coaxial with the drive chamber 225. The drive chamber 225 is closed by the moving cap 234a.

  The moving cap 234a has a female screw portion protruding on the rear end side, and this female screw portion is screwed to the male screw portion of the adjusting screw 234b, and the driving chamber is changed by changing the screwing amount with the adjusting screw 234b. Within 225, it is possible to advance and retract in the axial direction. The moving cap 234a can adjust the supply flow rate of the compressed air on the small diameter valve mechanism 220 side by increasing or decreasing the open area in the seal chamber 222 by contacting the convex portion 228a and changing the stop position of the small diameter spool 226 It has become.

As shown in the symbol in FIG. 2, the solenoid valve 240 has the neutral position 241 connected with P-A-B, the right position 242 with reverse connection (P-B, T-A connection), and the left position 243 connected in order. It is set as the port composition of three positions (PA, TB connection).
As shown in the figure, the first pilot passage 207 is connected to the discharge port A side of the solenoid valve 240, and the second pilot passage 208 is connected to the discharge port B side. Ports on the input side of the solenoid valve 240 are respectively connected to adapters 250f and 250g provided on the side surface of the main block 202 shown in FIG. 3B via a passage not shown.

As shown in FIG. 3A, a flow dividing chamber 204 is formed inside the flow dividing block 203. The flow dividing chamber 204 is opposed to the portion where the large diameter communication hole (upstream) 213 and the small diameter communication hole (upstream) 223 on the side surface of the main block 202 are opened as shown in FIG.
As shown in FIG. 3A, an adapter 250a is connected to the flow dividing block 203, and the adapter 250a and the flow dividing chamber 204 form a part of the upstream side pipeline 103a shown in FIG. Further, as shown in FIG. 3, an adapter 250c is provided in the flow dividing block 203, and the adapter 250c sends compressed air to another pneumatic device via a regulator RG (not shown).

  Further, as shown in FIG. 4, a merging chamber 206 is formed inside the merging block 205. The merging chamber 206 is opposed to a portion where the large diameter communication hole (downstream) 214 and the small diameter communication hole (downstream) 224 on the side surface of the main block 202 are open. As shown in FIG. 3, the adapter 250 b is connected to the merging block 205, and the adapter 250 b and the merging chamber 206 form a part of the downstream side pipeline 103 b shown in FIG. 2.

Furthermore, as shown in FIGS. 3 to 4, the merging block 205 is provided with an adapter 250 d, and the adapter 250 d is configured to supply lubricating oil from a lubricating pump LB (not shown) into the merging chamber 206. . Further, as shown in FIGS. 3 to 4, the merging block 205 is further provided with an adapter 250 e, and the adapter 250 e is configured to detect the pressure of the compressed air in the merging chamber 206 by a pressure sensor PG (not shown). There is.
Next, the operation and effects of the flow control valve 200 of the first embodiment will be described with reference to FIGS. 5 to 7.

[Operation 1. When stopping the supply of compressed air]
When the supply of compressed air is stopped, as shown in FIG. 5, the solenoid valve 240 is stopped at the neutral position 241 without being applied. In the neutral position 241, both the first pilot passage 207 and the second pilot passage 208 are connected to the pump P. As a result, all of the front chamber 215f and the rear chamber 215r of the large flow rate valve mechanism 210 and the front chambers 225f and 225r of the small flow rate valve mechanism 220 are connected at high pressure.

Therefore, the large diameter spool 216 and the small diameter spool 226 are respectively advanced toward the right side in the figure (a) according to (Equation 1) and (Equation 2) described above. In the same figure, the image which is connected at high voltage is illustrated by thick solid lines, hatching and hatching of the port portion (the same applies to the other drawings).
When the large diameter spool 216 advances and the sheet surface 217 a of the seal portion 217 abuts on the sheet surface 212 a of the seal chamber 212, the seal chamber 212 is closed. Thereby, the communication between the large diameter communication hole (upstream) 213 and the large diameter communication hole (downstream) 214 is blocked.

  Similarly, when the small diameter spool 226 advances and the sheet surface 227a of the seal portion 227 abuts on the sheet surface 222a of the seal chamber 222, the seal chamber 222 is closed. Thereby, the communication between the small diameter communication hole (upstream) 223 and the small diameter communication hole (downstream) 224 is blocked. Therefore, the upstream passage 103a and the downstream passage 103b are shut off, and no compressed air is supplied to the down-the-hole hammer 101, so the down-the-hole hammer 101 is stopped.

[Operation 2. When supplying compressed air at a small flow rate]
When compressed air is supplied at a small flow rate in the hole cutting operation, as shown in FIG. 6, it is applied to the right side of the solenoid valve 240, and the solenoid valve 240 is switched to the right position 242a. In the right position 242 a, the first pilot passage 207 is connected to the tank T, and the second pilot passage 208 is connected to the pump P.
Thus, the front chamber 215f of the large flow valve mechanism 210 and the rear chamber 225r of the small flow valve mechanism 220 are connected at low pressure, and the rear chamber 215r of the large flow valve mechanism 210 and the front chamber 225f of the small flow valve mechanism 220 are connected at high pressure. Therefore, the large diameter spool 216 advances toward the right side of FIG. 6A, and the small diameter spool retracts toward the left side of FIG.

  When the large diameter spool 216 advances and the sheet surface 217a of the seal portion 217 abuts against the sheet surface 212a of the seal chamber 212, the seal chamber 212 is closed and the large diameter communication hole (upstream) 213 and the large diameter communication hole (downstream Communication with 214) is cut off. On the other hand, when the small diameter spool 226 retreats and the sheet surface 227a of the seal portion 227 is released from contact with the sheet surface 222a of the seal chamber 222 and the seal chamber 222 is opened, the small diameter communicating hole (upstream) 223 and the small diameter It communicates with the communication hole (downstream) 224.

  Therefore, since the upstream passage 103a and the downstream passage 103b communicate with each other through the small flow rate valve mechanism 220, a small flow of compressed air is supplied to the down-the-hole hammer 101, and the hole cutting operation becomes possible. 6A shows a state in which the above-described stroke adjusting mechanism 234 is retracted to the rearmost end, and when the stroke adjusting mechanism 234 is adjusted and the moving cap 234a is advanced in the axial direction, the small diameter spool 226 It is possible to squeeze the flow rate of compressed air by advancing the open stop position of.

[Operation 3. When supplying compressed air at a large flow rate]
When compressed air is supplied at a large flow rate in this drilling operation, as shown in FIG. 7, it is applied to the left side of the solenoid valve 240 to switch the solenoid valve 240 to the left position 243. In the left position 242 b, the first pilot passage 207 is connected to the pump P, and the second pilot passage 208 is connected to the tank T.
Accordingly, the front chamber 215f of the large flow valve mechanism 210 and the rear chamber 225r of the small flow valve mechanism 220 are connected at high pressure, and the rear chamber 215r of the large flow valve mechanism 210 and the front chamber 225f of the small flow valve mechanism small flow supply structure 220. Is connected at low pressure. Therefore, the large diameter spool 216 retracts toward the left side in the figure (a), and the small diameter spool advances toward the right side in the figure (a).

When the small diameter spool 226 advances and the sheet surface 227a of the seal portion 227 abuts on the sheet surface 222a of the seal chamber 222, the seal chamber 222 is closed, and the small diameter communication hole (upstream) 223 and the small diameter communication hole (downstream) 224 Communication is interrupted.
On the other hand, when the large diameter spool 216 retracts and the sheet surface 217a of the seal portion 217 is released from contact with the sheet surface 212a of the seal chamber 212 and the seal chamber 212 is opened, the large diameter communication hole (upstream) 213 And the large diameter communication hole (downstream) 214 communicate with each other. Therefore, the upstream passage 103a and the downstream passage 103b communicate with each other through the large flow valve mechanism 210, so that a large flow of compressed air is supplied to the down-the-hole hammer 101, and the hole operation can be performed.

  Thus, in the down-the-hole hammer 101 which is an air pressure drilling machine, the flow control valve 200 has a valve block 201 which is a valve main body and a solenoid valve 250 which is a control unit. A large diameter valve chamber 211 and a small diameter valve chamber 221, which slidably accommodates the small diameter spool 226 and the small diameter spool 216, respectively, are provided. The large diameter valve chamber 211 and the small diameter valve chamber 221 are used to retract the large diameter spool 216 and the small diameter spool 226, respectively. · A large diameter communication hole 213 and a small diameter communication hole 223 for opening / closing the supply path 103 of compressed air by opening and closing by forward movement are respectively opened, and the large diameter spool 216 and the small diameter spool 226 are solenoid valves Down the hole hammer 10 by operating with pilot oil pressure supplied from 250 Stop of compressed air to (5), it is possible to selectively perform the low flow supply (FIG. 6) and high flow supply (Figure 7).

In particular, according to the first embodiment, the large flow rate valve mechanism 210 and the small flow rate valve mechanism 220 are configured with specification values corresponding to the flow rates of the compressed air flowing through them. That is, since the diameter and pressure receiving area of each of the spools 216 and 226 are set based on (Equation 1) and (Equation 2) described above, each configuration of the large flow rate valve mechanism 210 has a large diameter, Each configuration of the low flow rate valve mechanism 220 has a small diameter.
Therefore, the entire apparatus can be compacted, and the most suitable seal can be selected, so that the cost can be reduced. In addition, since the amount of pilot oil for driving each of the spools 216 and 226 is also optimized, energy efficiency is good.

Modification of First Embodiment
Next, a modification of the first embodiment will be described. FIG. 8 is a circuit diagram of a flow control valve 200 'which is a modification of the first embodiment of the present invention. As shown in the figure, this modification and the first embodiment are different in that the large flow valve mechanism 210 and the small flow valve mechanism 220 are provided with solenoid valves 243 individually. The present modification is the same as the first embodiment except that the solenoid valve 243 is separately provided to the large flow valve mechanism 210 and the small flow valve mechanism 220, and therefore the description of the other configuration and operation is omitted.

That is, as shown in the figure, the stop position 244a has a PB and TA connection, and the switch position 244b has a PA and TB connection for the large flow valve mechanism 210 and the small flow valve mechanism 220, respectively. A two-position port configuration solenoid valve 243 is provided.
The discharge port of one solenoid valve 243 and the large diameter front chamber 215f are in communication with each other by the large diameter pilot passage 207a, and the large diameter rear chamber 215r is in communication with the large diameter pilot passage 207b. Similarly, the discharge port of the other solenoid valve 243 and the small diameter front chamber 225f are in communication with each other by the small diameter pilot passage 208a, and the small diameter rear chamber 225r is in communication with the small diameter pilot passage 208b.

In this modification, the two solenoid valves 243 are selectively switched to operate the large flow valve mechanism 210 and the small flow valve mechanism 220. As a result, even with the configuration of this modification, as in the first embodiment, it is possible to selectively perform stop of compressed air, supply of a small amount of flow, and supply of a large amount of flow to the down-the-hole hammer 101.
In addition, although this modification is disadvantageous in cost because the two solenoid valves 243 are provided as compared with the first embodiment, it is easy to manufacture because it does not have the merging structure of the pilot passage. Further, when both solenoid valves 243 are switched simultaneously, it is also possible to open the communication holes of both the large flow rate valve mechanism and the small flow rate valve mechanism and supply compressed air of the flow rate added up and down.

Second Embodiment
Next, a second embodiment will be described. FIG. 9 is a circuit diagram of a flow control valve 300 according to a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the spools housed in the respective valve chambers have a straight shape with no difference in diameter, and a "single-acting spool type" provided with biasing means for biasing each spool. And the point. In the same figure (b), since the large diameter spool 311 and the small diameter spool 321 of the second embodiment have the same configuration except that the diameter dimension is different, the small diameter spool 321 corresponding to the large diameter spool 311. The composition of is described in parentheses.

  As shown in the figure, the large flow rate valve mechanism 310 according to the second embodiment accommodates the large diameter spool 311 so as to be able to advance and retract in the large diameter valve chamber 210 common to the first embodiment. The large diameter spool 311 has a straight body portion 312a, a seat surface 312b and a convex portion 312c, as shown in FIG. A coil spring 313 is interposed in the seal chamber 212 as urging means so as to elastically press the large diameter spool 311 rearward in the axial direction. A large diameter pilot passage 301 is connected to the drive chamber 215, and pilot hydraulic pressure is supplied and discharged from the solenoid valve 240.

The large diameter spool 311 has a pressure receiving area Sd1 corresponding to the diameter of the straight body portion 312a in the drive chamber 215 and in the seal chamber 212, Pp for pilot oil pressure, Pa for compressed air pressure, and thrust of a coil spring. Assuming that Pc, dimensions, pressures and the like of each part are set so as to be the following (Equation 3).
Sd1 × Pp> Sd1 × Pa + Pc (Equation 3)

  The small flow rate valve mechanism 320 accommodates the small diameter spool 321 so as to be able to move forward and backward in the small diameter valve chamber 220 common to the first embodiment. The small diameter spool 321 has a straight body portion 322a, a seat surface 322b, and a convex portion 322c, as shown in parentheses in FIG. A coil spring 323 as an urging means is interposed in the seal chamber 222 so as to elastically press the small diameter spool 321 rearward in the axial direction. The small diameter pilot passage 302 is connected to the drive chamber 225, and pilot hydraulic pressure is supplied and discharged from the solenoid valve 240.

The small diameter spool 321 has a pressure receiving area Sd2 corresponding to the diameter of the straight body 322a in the drive chamber 225 and the seal chamber 222, Pp for pilot oil pressure, Pa for compressed air pressure, and Pc for the coil spring. Then, the dimensions, the pressure, and the like of each part are set such that (Expression 4) below is obtained.
Sd2 × Pp> Sd2 × Pa + Pc (Equation 4)

  In the second embodiment, as shown in FIG. 7A, when the solenoid valve 240 is in the neutral position 241, pilot hydraulic pressure is supplied to both the large diameter drive chamber 215 and the small diameter drive chamber 225. The diameter spool 311 and the small diameter spool 321 move forward to contact the large diameter seat surfaces 212a and 312b and the small diameter seat surfaces 222a and 322b, respectively, and the large diameter seal chamber 212 and the small diameter seal chamber 222 are closed together. As a result, the large diameter communication holes 213 and 214 and the small diameter communication rows 223 and 224 are both blocked, so the upstream passage 103 a and the downstream passage 103 b are blocked and compressed air is not supplied to the down the hole hammer 101. Hammer 101 stops.

  On the other hand, when the solenoid valve 240 is switched to the right position 242a, although not shown, the large diameter pilot passage 301 is connected to the pump P and the small diameter pilot passage 302 is connected to the tank T. As a result, the large diameter drive chamber 215 is connected at high pressure, and the small diameter drive chamber 225 is connected at low pressure. Thus, the large diameter spool 311 advances, and the small diameter spool 321 retracts.

  When the small diameter spool 321 retracts and the contact between the sheet surface 322b of the straight body 322a and the sheet surface 222a of the seal chamber 222 is released to open the seal chamber 222, the small diameter communication hole (upstream) 223 and small diameter communication The hole (downstream) 224 is in communication, and the upstream passage 103a and the downstream passage 103b are in communication through the small flow rate valve mechanism 220, so a small flow of compressed air is supplied to the down the hole hammer 101 and the hole cutting operation is possible. It becomes.

Furthermore, when the solenoid valve 240 is switched to the left position 242b, although not shown, the large diameter pilot passage 301 is connected to the tank T, and the small diameter pilot passage 302 is connected to the pump P. As a result, the large diameter drive chamber 215 is connected at low pressure, and the small diameter drive chamber 225 is connected at high pressure. Thus, the large diameter spool 311 retracts, and the small diameter spool 321 advances.
When the large diameter spool 311 retracts and the contact between the sheet surface 312b of the straight barrel portion 312a and the sheet surface 212a of the seal chamber 212 is released to open the seal chamber 212, the large diameter communication hole (upstream) 213 and The large diameter communication hole (downstream) 214 is in communication, and the upstream passage 103a and the downstream passage 103b are in communication through the large flow valve mechanism 310, so a large flow of compressed air is supplied to the down-the-hole hammer 101 and the hole operation is performed. Is possible.

  Thus, compared with the first embodiment, the second embodiment can simplify the configuration of the spool and the pilot passage by adopting the single acting spool type. Further, in the second embodiment, as in the first embodiment, each valve chamber is constituted by the seal chamber and the drive chamber having a large diameter. Since the inner diameter of the drive chamber is a single-acting spool, The processing cost can be reduced because it is not necessary to finish to cope with metal contact. In addition, since the thrust of the coil springs 313 and 323 provided as biasing means may be a grade which assists a cracking pressure, a simple thing can be adopted.

Modification of Second Embodiment
Next, a modification of the second embodiment will be described. FIG. 10 is a circuit diagram of a flow control valve 300 'which is a modification of the second embodiment.
The difference between this modification and the second embodiment is that, as shown in the figure, the solenoid valve 245 has a port configuration in which the stop position 246a is PA connection and the switching position 246b is TA connection. The solenoid valve 245 is provided to the large flow rate valve mechanism 310 and the small flow rate valve mechanism 320 separately.

  The discharge port A of each solenoid valve 245 is connected to the large diameter drive chamber 215 of the large flow rate valve mechanism 310 via the large diameter pilot passage 301 ′, and the small diameter drive chamber 225 of the small flow rate valve mechanism 320 has a small diameter It is connected via the pilot passage 302 '. The present modification is the same as the second embodiment except that the solenoid valve 245 is separately provided to the large flow valve mechanism 310 and the small flow valve mechanism 320, respectively, and therefore, the description of the other configuration and operation is given. Is omitted.

In the modification of the second embodiment, stopping the compressed air to the down-the-hole hammer 101 by switching the two solenoid valves 245 selectively to operate the large flow valve mechanism 310 and the small flow valve mechanism 320. It is possible to carry out flow supply and high flow supply.
Although this modification is disadvantageous in cost due to the provision of two solenoid valves 245 as compared with the second embodiment, the high flow rate valve mechanism 310 and the low flow rate are obtained when both solenoid valves 245 are switched simultaneously. It is possible to open both communication holes of the valve mechanism 320 to supply compressed air at a flow rate that is the sum of the magnitudes.

Third Embodiment
Next, the third embodiment will be described. FIG. 11 is a circuit diagram of a flow control valve 350 according to a third embodiment of the present invention. The difference between the third embodiment and the first embodiment is that in the drive chambers defined in the front and rear chambers, the pilot pressure is supplied by hydraulic pressure and the side opposite to the chamber to which the pilot hydraulic pressure is supplied. The point is to supply compressed air to the chamber.

  That is, as shown in FIG. 11, the large diameter rear chamber 215r of the large flow rate valve mechanism 360 of the third embodiment and the small diameter rear chamber 225r of the small flow rate valve mechanism 370 of the third embodiment Each is connected to the discharge port. A large diameter pneumatic passage 353a and a small diameter pneumatic passage 353b which are further branched from a branch passage 353 branched from the upstream passage 103a of the compressed air supply passage 103 are connected to the large diameter front chamber 215f and the small diameter front chamber 225f. There is.

In the large diameter spool 216, the pressure receiving area Sr1 of the rear chamber 215r is equal to the sum of the pressure receiving area Sf1 of the front chamber 215f and the pressure receiving area Ss1 of the seal chamber 212. On the other hand, thrust due to the hydraulic pressure is generated on the rear chamber 215r side (left side in FIG. 11), and the thrust due to air pressure is generated on the front chamber 215f side and the seal chamber 212 side (right side in FIG. 11). Do. Assuming that the pilot hydraulic pressure at this time is Pp and the pressure of the compressed air is Pa, each supply pressure is set so as to be the following (Equation 5). Since this relationship is the same for the small diameter spool 226, the description is omitted.
Sr1 × Pp> (Sf1 + Ss1) × Pa
∴ P p> Pa (Equation 5)

  As shown in FIG. 11, when the solenoid valve 240 is in the neutral position 241, pilot hydraulic pressure is supplied to both the large diameter rear chamber 215r and the small diameter rear chamber 225r. Therefore, the large diameter spool 216 and the small diameter spool 216 move forward, and the large diameter seat surfaces 212a and 217b and the small diameter seat surfaces 222a and 227b abut, respectively, and the large diameter seal chamber 212 and the small diameter seal chamber 222 are closed together. . The large diameter communication holes 213 and 214 and the small diameter communication rows 223 and 224 are both shut off, the upstream passage 103 a and the downstream passage 103 b are blocked, and the down-the-hole hammer 101 is stopped because compressed air is not supplied.

When the solenoid valve 240 is switched to the right position 242 a, the large diameter pilot passage 351 is connected to the pump P, and the small diameter pilot passage 352 is connected to the tank T. As a result, the large diameter rear chamber 215r is connected at high pressure, and the small diameter rear chamber 225r is connected at low pressure. Thus, the large diameter spool 216 advances, and the small diameter spool 226 retracts.
When the small diameter spool 226 is retracted and the contact between the sheet surface 227a of the seal portion 227 and the sheet surface 222a of the seal chamber 222 is released to open the seal chamber 222, the small diameter communication hole (upstream) 223 and the small diameter communication hole The downstream side 224 is in communication, and the upstream side passage 103 a and the downstream side passage 103 b are in communication via the small flow rate valve mechanism 370. Therefore, a small amount of compressed air is supplied to the down-the-hole hammer 101, and the hole cutting operation becomes possible.

When the solenoid valve 240 is switched to the left position 242b, the large diameter pilot passage 351 is connected to the tank T, and the small diameter pilot passage 352 is connected to the pump P. As a result, the large diameter rear chamber 215r is connected at low pressure, and the small diameter rear chamber 225r is connected at high pressure. Thus, the large diameter spool 216 retracts, and the small diameter spool 226 advances.
When the large diameter spool 216 retracts and the contact between the sheet surface 217a of the sealing portion 217 and the sheet surface 212a of the sealing chamber 212 is released to open the sealing chamber 212, the large diameter communicating hole (upstream) 213 and the large diameter The communication hole (downstream) 214 is in communication, and the upstream passage 103 a and the downstream passage 103 b are in communication via the large flow valve mechanism 360. Therefore, a large flow of compressed air is supplied to the down-the-hole hammer 101, and the hole operation can be performed.

  In the third embodiment, compared to the first embodiment, the pneumatic passage is newly provided instead of simplifying the configuration of the pilot passage. However, this pneumatic passage can be easily processed since it is sufficient to connect the flow dividing chambers 204 of the flow dividing block 203 with the respective front chambers, so that the processing is easy and the overall processing cost is reduced. In addition, since the pilot hydraulic pressure that is usually used is set higher than the compressed air pressure, there is no need to adjust the pressure specially.

Modification of Third Embodiment
Next, a modification of the third embodiment will be described. FIG. 12 is a circuit diagram of a flow control valve 350 'which is a modification of the third embodiment. The difference between this modification and the third embodiment is that the stop position 248 is a T-A-B connection, the right position 249a is a reverse connection (P-B, T-A connection), and the left position 249 b is a forward connection (P (A, TB connection) using a solenoid valve 247 having a three-position port configuration, and also using an air pressure thrust generated by compressed air supplied branched from the compressed air supply path 103 as an energizing means It is.

  That is, as shown in the figure, in each discharge port, the discharge port B is connected to the large diameter front chamber 215f via the large diameter pilot passage 351 ', and the discharge port A is small diameter via the small diameter pilot passage 352'. It is connected to the front room 225f. In the large diameter rear chamber 215r and the small diameter rear chamber 225r, a large diameter air pressure passage 353a 'and a small diameter air pressure passage 353b' which are further branched from a branch passage 353 'branched from the upstream passage 103a of the compressed air supply passage 103 respectively. It is connected.

Assuming that the pressure receiving area Sr1 of the rear chamber 215r, the pressure receiving area Sf1 of the front chamber 215f, and the pressure receiving area Ss1 of the seal chamber 212 in the large diameter spool 216, the pilot hydraulic pressure is Pp, and the pressure of compressed air is Pa, Set each supply pressure to be). Since this relationship is the same for the small diameter spool 226, the description is omitted.
Sr1 × Pa <Sf1 × Pp + Ss1 × Pa
(Sr1-Ss1) × Pa <Sf1 × Pp
Sf1 × Pa <Sf1 × Pp
∴ Pa <Pp (6)

As shown in FIG. 12, with the solenoid valve 247 in the neutral position 248, both the large diameter front 215f and the large diameter front 225f are connected to the tank T. At this time, compressed air is supplied to the large diameter rear chamber 215 r and the small diameter rear chamber 225 r, and the large diameter seal chamber 212 and the small diameter seal chamber 222.
However, the large diameter spool 216 and the small diameter spool 216 move forward together due to the pressure receiving area difference between the rear chamber and the seal chamber, the large diameter sheet surfaces 212a and 217b abut, and the small diameter sheet surfaces 222a and 227b abut, respectively The large diameter seal chamber 212 and the small diameter seal chamber 222 are both closed.

Accordingly, the large diameter communication holes 213 and 214 and the small diameter communication rows 223 and 224 are both blocked, and the upstream passage 103a and the downstream passage 103b are blocked and compressed air is not supplied to the down the hole hammer 101, so the down the hole hammer 101 is stopped. Do.
When the solenoid valve 247 is switched to the right position 249a, the large diameter pilot passage 351 'is connected to the pump P, and the small diameter pilot passage 352' is connected to the tank T. Thus, the large diameter front chamber 215f is connected at high pressure, and the small diameter front chamber 225f is connected at low pressure. Thus, the large diameter spool 216 retracts, and the small diameter spool 226 advances.

  When the large diameter spool 216 retracts and the contact between the sheet surface 217a of the sealing portion 217 and the sheet surface 212a of the sealing chamber 212 is released to open the sealing chamber 212, the large diameter communicating hole (upstream) 213 and the large diameter Since the communication hole (downstream) 214 is in communication, and the upstream passage 103a and the downstream passage 103b are in communication via the large flow valve mechanism 360 ', a large flow of compressed air is supplied to the down the hole hammer 101 and the hole operation is performed It becomes possible.

When the solenoid valve 247 is switched to the left position 249 b, the large diameter pilot passage 351 ′ is connected to the tank T, and the small diameter pilot passage 352 ′ is connected to the pump P. As a result, the large diameter front chamber 215f is connected at low pressure, and the small diameter front chamber 225f is connected at high pressure. Thus, the large diameter spool 216 advances, and the small diameter spool 226 retracts.
When the small diameter spool 226 is retracted and the contact between the sheet surface 227a of the seal portion 227 and the sheet surface 222a of the seal chamber 222 is released to open the seal chamber 2212, the small diameter communication hole (upstream) 223 and the small diameter communication hole Since the downstream side 224 is in communication, and the upstream side passage 103a and the downstream side passage 103b are in communication via the small flow rate valve mechanism 370 ', a small flow of compressed air is supplied to the down-the-hole hammer 101 to enable hole cutting operation. .

In the modification of the third embodiment, when the supply of the compressed air is stopped, it is not necessary to continuously supply the pilot hydraulic pressure, which leads to energy saving. In addition, the amount of pilot oil that operates each spool only needs to fill the front chamber, which leads to energy saving.
As mentioned above, although the embodiment and modification of the present invention were explained with reference to drawings, the flow control valve for pneumatic drilling machines concerning the present invention is not limited to the above-mentioned embodiment and modification, and the present invention It goes without saying that various other modifications and changes in each component can be made without departing from the spirit of the invention.

100 down the hole drill (pneumatic drilling machine)
101 down-the-hole hammer 102 compressor 103 compressed air supply path 103a, 103b upstream side pipe line, downstream side pipe line 200, 200 'flow control valve 201 valve block (valve body)
202 Main block 203 Divided block 204 Divided chamber 205 Merged block 206 Merged chamber 207 First pilot passage 207a, 207b Large diameter pilot passage (front chamber), large diameter pilot passage (rear chamber)
208 Second pilot passage 208a, 208b Small diameter pilot passage (front chamber), small diameter pilot passage (rear chamber)
210 Large flow rate valve mechanism 211 Large diameter valve chamber 212 Seal chamber 212a, 212b Seat surface, enlarged diameter portion 213 Large diameter communication hole (upstream)
214 Large diameter communicating hole (downstream)
215 driving chamber 215f, 215r front chamber, rear chamber 216 large diameter spool (double acting)
217, 217a seal portion, seat surface 218, 218a drive portion, convex portion 220 small flow rate valve mechanism 221 small diameter valve chamber 222, 222a, 222b seal chamber, seat surface, enlarged diameter portion 223 small diameter communicating hole (upstream)
224 Small diameter communication hole (downstream)
225, 225f, 225r Drive chamber, front chamber, rear chamber 226 Small diameter spool (double acting)
227, 227a Seal portion, seat surface 228, 228a Drive portion, convex portion 230 cover (large)
231 Fixing cap 232 Mounting hole 233 Cover (small)
234, 234a, 234b Stroke adjustment means, moving cap, adjustment screw 240 solenoid valve (control part)
241 Neutral position (P-A-B connection)
242a, 242b Right position (reverse connection), Left position (forward connection)
243 Solenoid valve 244a, 244b Stop position (reverse connection), switching position (forward connection)
245 Solenoid valve 246a, 246b Stop position (P-A connection), Switching position (T-A connection)
247 Solenoid valve 248 Neutral position (TAB connection)
249a, 249b Right position (reverse connection), Left position (forward connection)
250a to 250g Adapters (a) to (g)
300, 300 'flow control valve 301, 301' large diameter pilot passage 302, 302 'small diameter pilot passage 310 large flow valve mechanism 311 large diameter spool (single acting)
312a, 312b, 312b Straight body portion, seat surface, convex portion 313 coil spring (biasing means)
320 Small flow valve mechanism 321 Small diameter spool (single acting)
322a, 322b, 322b Straight body portion, seat surface, convex portion 323 coil spring (biasing means)
350, 350 'flow control valve 351, 351' large diameter pilot passage 352, 352 'small diameter pilot passage 353 branch passage 353a, 353b large diameter pneumatic passage, small diameter pneumatic passage 360 large flow valve mechanism 370 small flow valve mechanism RG regulator LB lubricating pump PG pressure sensor P hydraulic pump T tank

Claims (8)

A flow control valve for use in a pneumatic drilling machine and disposed in one compressed air supply path between the pneumatic drilling machine and a compressor, comprising:
A valve body having a large diameter valve chamber slidably accommodating a large diameter spool and a small diameter valve chamber slidably accommodating a small diameter spool, and a pilot for operating the large diameter spool and the small diameter spool of the valve body A control unit for supplying hydraulic pressure;
The large diameter valve chamber has a large diameter communication hole that opens and closes by forward and backward movement of the large diameter spool to connect and disconnect the compressed air supply path.
A flow control valve for a pneumatic drilling machine, wherein the small diameter valve chamber has a small diameter communication hole which opens and closes by connecting the small diameter spool back and forth to connect and disconnect the compressed air supply path. The large-diameter valve chamber includes a large-diameter seal chamber in which a large-diameter communication hole is opened, a large-diameter drive chamber separated from the large-diameter seal chamber by a large-diameter spool, and a pilot supplied to the large-diameter drive chamber. Biasing means for biasing the large diameter spool in a direction opposite to the thrust applied to the large diameter spool by hydraulic pressure;
The large-diameter spool has a large-diameter straight barrel corresponding to the diameter of the large-diameter seal chamber, and is a single-acting spool operated by supplying and discharging a pilot hydraulic pressure from the position of the large-diameter straight barrel to the large-diameter drive chamber. Yes,
The small-diameter valve chamber is given to the small-diameter spool by a small-diameter seal chamber in which a small-diameter communication hole opens, a small-diameter drive chamber separated from the small-diameter seal chamber by a small-diameter spool, and a pilot hydraulic pressure supplied to the small-diameter drive chamber. Biasing means for biasing the small diameter spool in the direction opposite to the thrust force
The small-diameter spool is a single-acting spool that has a small-diameter straight body corresponding to the diameter of the small-diameter seal chamber and is actuated by supplying and discharging pilot hydraulic pressure from the position of the small-diameter straight barrel to the small-diameter drive chamber. The flow control valve for pneumatic drilling machines according to 1. The large diameter valve chamber has a large diameter seal chamber in which a large diameter communication hole is opened, and a large diameter drive chamber having a diameter larger than the large diameter seal chamber,
The large diameter spool has a large diameter seal portion corresponding to the diameter of the large diameter seal chamber, and a large diameter drive portion corresponding to the diameter of the large diameter drive chamber,
In the large diameter drive chamber, a large diameter front chamber is defined on the large diameter seal chamber side by the large diameter spool, and a large diameter rear chamber is defined on the opposite side, and the large diameter front chamber is formed. The large diameter spool is configured to advance and retract by supplying and discharging a pilot hydraulic pressure to at least one of the rear chamber and the rear chamber.
The small-diameter valve chamber has a small-diameter seal chamber in which a small-diameter communication hole is opened, and a small-diameter drive chamber having a diameter larger than that of the small-diameter seal chamber.
The small diameter spool has a small diameter seal portion corresponding to the diameter of the small diameter seal chamber, and a small diameter drive portion corresponding to the diameter of the small diameter drive chamber,
In the small-diameter drive chamber, a small-diameter front chamber is defined on the small-diameter seal chamber side by the small-diameter spool, and a small-diameter rear chamber is defined on the opposite side, and at least one of the small-diameter front chamber and the rear chamber The flow control valve for a pneumatic drilling machine according to claim 1, wherein the small diameter spool is advanced and retracted by supplying and discharging a pilot hydraulic pressure. Each of the large diameter and small diameter spools is configured to close the respective communication holes by its forward movement and to open the respective communication holes by its backward movement,
The front chamber of the large diameter drive chamber and the rear chamber of the small diameter drive chamber are connected to form a first pilot passage, and the rear chamber of the large diameter drive chamber and the front chamber of the small diameter drive chamber are connected. Form a second pilot passage,
The control unit is a solenoid valve having a three-position port configuration in which the neutral position is P-A-B connected and forward connection and reverse connection are arranged on both sides thereof, and the two discharge ports of the solenoid valve The flow control valve for a pneumatic drilling machine according to claim 3, wherein the first pilot passage and the second pilot passage are respectively connected. Each of the large diameter and small diameter spools is configured to close the respective communication holes by its forward movement and to open the respective communication holes by its backward movement,
The control unit is a solenoid valve having a three-position port configuration in which the neutral position is P-A-B connected and forward connection and reverse connection are arranged on both sides thereof, and the two discharge ports of the solenoid valve The large diameter and small diameter valve chambers are configured to communicate with respective rear chambers,
The large diameter and small diameter valve chambers are provided with biasing means for biasing the respective spools in the direction opposite to the thrust applied to the respective spools by the pilot hydraulic pressure supplied to the respective rear chambers. The flow control valve for pneumatic drilling machines according to Item 3. Each of the large diameter and small diameter spools is configured to close the respective communication holes by its forward movement and to open the respective communication holes by its backward movement,
The control unit is a solenoid valve having a three-position port configuration in which the neutral position is T-A-B connected and forward connection and reverse connection are disposed on both sides thereof, and the two discharge ports of the solenoid valve The large diameter and small diameter valve chambers are configured to communicate with respective front chambers,
The large diameter and small diameter valve chambers are provided with biasing means for biasing the respective spools in the direction opposite to the thrust applied to the respective spools by the pilot hydraulic pressure supplied to the respective front chambers. The flow control valve for pneumatic drilling machines according to Item 3.   The biasing means is an air pressure thrust generated by compressed air supplied branched from the compressed air supply path in a drive chamber opposite to a front chamber or a rear chamber to which the discharge port is connected. Item 7. A flow control valve for a pneumatic drilling machine according to any one of Items 4 to 6.   The pneumatic drilling machine according to any one of claims 1 to 7, wherein at least one of the large diameter valve chamber and the small diameter valve chamber is provided with an adjustment means for adjusting the amount of retraction of the at least one spool. Flow control valve.

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