JP2005177899A - Hydraulic hammering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic hammering device capable of automatically changing a hammering stroke at least in two stages and efficiently and accurately performing the stroke control. <P>SOLUTION: The hydraulic hammering device 1 hammering a chisel 3 by reciprocating an impact piston 2 is provided with a stroke control valve 25 switched based on the pressure difference between upper and lower chambers 10, 11 of the hammering piston 2 caused by the hardness difference of an hammering object in hammering the object, and a holding mechanism for holding the stroke control valve 25 in the switched position. The hydraulic hammering device 1 is constituted to control the following hammering stroke at least in two stages based on the switched position of the stroke control valve 25. The hydraulic hammering device is provided with a front control valve 29 for putting the upper chamber 10 of the hammering piston 2 in communication with a driving chamber SV3 of the stroke control valve 25 to apply a hydraulic signal to the driving chamber SV3 from the upper chamber 10 in hammering the hammering object. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydraulic striking device that strikes a chisel by reciprocating a striking piston, and particularly relates to a technique for automatically changing the stroke of a striking piston according to the hardness of a striking object.

  Conventionally, as a striking device that automatically changes the stroke of a striking piston according to the hardness of a striking object, for example, a device that can be found in Patent Document 1 has been provided.

  Specifically, an instantaneous pressure fluctuation in the upper or lower chamber of the striking piston that occurs at the moment of striking the striking piston is compared with a reference pressure, and the control flow rate generated according to the pressure difference is controlled by the operating means. It is used as.

For example, the stroke of the striking piston can be changed by changing the operating pressure by changing the position of the spool that controls the discharge passage, or by changing the position of the stroke selection slide valve according to the control flow rate according to the pressure difference. The batting power or the number of batting is adjusted.
Japanese Patent Publication No. 5-85311

  However, in the above-described conventional one, the function of holding the position of the spool and the stroke selection slide valve and releasing it is not added. Accordingly, it is necessary to allow for considerable redundancy in order to hold the spool and the stroke selection slide valve at a required position until necessary, while taking in and discharging the flow rate corresponding to the measured pressure difference. For this reason, it is not efficient such that the entire apparatus becomes large or a time difference occurs until the device reaches a desirable occupied position with respect to the hardness of the hit object.

  In addition, in the case of a fluid whose viscosity changes depending on the temperature, such as oil, the influence of the fluid temperature acts greatly, so that the stroke control as described above cannot be performed accurately.

  In order to achieve the above object, the hydraulic striking device according to the first aspect of the present invention is a hydraulic striking device that strikes a chisel by reciprocating a striking piston. A stroke control valve that is switched based on a pressure difference between the upper and lower chambers of the striking piston caused by a difference in the hardness of the object, and a holding mechanism that holds the stroke control valve at its switching position. The next hitting stroke is controlled in at least two stages based on the position.

  The hydraulic striking device of the invention according to claim 2 is driven from the upper chamber by communicating the chamber above the striking piston and the drive chamber of the stroke control valve at the time of striking the striking object. A pre-control valve for applying a hydraulic signal to the chamber is provided.

  In the hydraulic striking device according to a third aspect of the present invention, the holding mechanism includes a holding valve that holds the spool of the stroke control valve at each moving position.

  According to the hydraulic striking device of the present invention, when striking a striking object, the stroke control valve is switched based on the pressure difference between the upper and lower chambers of the striking piston caused by the difference in hardness of the striking object. Thus, the next striking stroke can be automatically changed to one of two stages, for example, a short stroke and a long stroke. Further, the stroke control of the striking piston can be performed efficiently and accurately by holding the switching position of the stroke control valve by the holding mechanism provided in the hydraulic circuit and controlling the stroke of the striking piston.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 shows the overall configuration of the hydraulic striking device of the present invention.

  This striking device 1 is generally mounted as an attachment to a construction machine such as a hydraulic excavator, and is used when crushing concrete or rock at a civil engineering site or a quarry using a working fluid supplied from a hydraulic power source. It is.

  First, the outline of the striking device 1 will be described. The striking piston 2 having two pressure receiving surfaces PS1 and PS2 (PS1> PS2) having different areas is provided, and the pressure receiving surface PS2 having a small area is constantly pressurized from a hydraulic power source through a hydraulic circuit. A high pressure and a low pressure are applied alternately to the pressure-receiving surface PS1 having a large area from a hydraulic source through a hydraulic circuit. When a low pressure is acting on the pressure receiving surface PS1, the striking piston 2 compresses the gas against the gas pressure acting on the top pressure receiving surface PS0 of the striking piston 2 due to the high pressure acting on the pressure receiving surface PS2. The return stroke is performed, and when a high pressure is acting on the pressure receiving surface PS1, the striking stroke is performed by the high pressure and the gas pressure acting on the pressure receiving surface PS1.

  Hereinafter, a specific configuration of the striking device 1 will be described.

  In FIG. 1, C is a casing, and this casing C is connected to a cylinder chamber C1 in which the striking piston 2 is reciprocally slidable in the axial direction, and is connected to one end (lower end side) of the cylinder chamber C1. The housed chisel chamber C2 is constituted by a gas chamber C3 connected to the other end (upper end side) of the cylinder chamber C1 and filled with a gas such as nitrogen.

  The striking piston 2 has two large diameter portions 2a, 2b formed at a predetermined distance in the middle, and the peripheral surfaces of these two large diameter portions 2a, 2b are slidable in the cylinder chamber C1. Has been placed. The end surface of the upper shaft portion 2c connected to the large diameter portion 2a faces the gas chamber C3, and the end surface of the lower shaft portion 2d connected to the large diameter portion 2b faces the chisel chamber C2. Has been placed.

  Further, the upper and lower shaft portions 2c and 2d are such that the upper shaft portion 2c has a smaller diameter than the lower shaft portion 2d. As a result, the pressure receiving surface PS1 of the large diameter portion 2a is the pressure receiving surface of the large diameter portion 2b. It is larger than PS2 (PS1> PS2).

  Furthermore, a plurality of grooves 4 to 9 are annularly formed in the axial direction in the cylinder chamber C1. These grooves 4 to 9 are sequentially formed from the upper end side (left end side) to the lower end side of the cylinder chamber C1. The groove 4 is formed facing a storage chamber (upper chamber) 10 formed between the upper shaft portion 2c and the cylinder chamber C1, and the groove 9 is formed between the lower shaft portion 2d and the cylinder chamber C1. It is formed facing the storage chamber (lower room) 11 formed in the above.

  In addition, the groove 6 and the groove 7 are formed on the shaft portion 2e formed between the large-diameter portions 2a and 2b of the striking piston 2 when the striking piston 2 is disposed at the theoretical striking position L as shown in FIG. The groove 6 communicates with the tank 12, and the groove 6 communicates with the tank T through the oil passage 13 to be at a low pressure.

  On the other hand, a brake chamber 15 is formed in the cylinder chamber C1 on the lower end side of the groove 9, and when the striking piston 2 is disposed at the theoretical striking position L as shown in FIG. The surface PS2 is arranged without entering the brake chamber 15.

  These grooves 4 to 9 and the brake chamber 15 communicate with respective oil passages incorporated in a hydraulic circuit described later.

  The chisel chamber C2 is a portion that houses the chisel 3 as described above. The chisel 3 is arranged with its tip projecting a predetermined length, and when the striking piston 2 moves to the theoretical striking position L. It arrange | positions so that the said impact piston 2 and its base end may contact | abut.

  The gas chamber C3 urges the striking piston 2 in the striking direction by the gas pressure sealed therein. That is, the end surface of the upper shaft portion 2c disposed facing the gas chamber C3 is a pressure receiving surface PS0 that receives the gas pressure.

  Next, a specific configuration of the hydraulic circuit will be described with reference to FIG.

  The discharge side of the hydraulic pump P communicates with the control valve 21 through the oil passage 20. An oil passage 22 and an oil passage 23 are branched from the oil passage 20. The oil passage 22 communicates with one drive chamber CV 2 of the control valve 21, and the oil passage 23 communicates with the groove 9.

  The control valve 21 is a two-position switching valve, and the other driving chamber CV1 communicates with one of the outlets of the stroke control valve 25 through the oil passage 24 and acts on the driving chamber CV1 and the driving chamber CV2. The position is switched between the upper position (A circuit) and the lower position (B circuit) in FIGS.

  Specifically, when the control valve 21 is in the A circuit, the communication between the oil passage 20 and the oil passage 26 communicated with the groove 4 is blocked, and the oil passage 26 and the oil passage 27 communicated with the tank T are connected. Communicate. Therefore, when the control valve 21 is arranged in the A circuit, the storage chamber 10 is in a low pressure because the groove 4 communicates with the tank T.

  Further, when the control valve 21 is a B circuit, the oil passage 20 and the oil passage 26 are communicated, whereby the working fluid from the hydraulic pump P is introduced into the storage chamber 10 through the groove 4, and the storage chamber 10 is Use high pressure.

  That is, high pressure and low pressure act alternately on the pressure receiving surface PS1 of the large diameter portion 2a by switching the control valve 21.

  An oil passage 28 is branched from the oil passage 26, and the oil passage 28 communicates with the drive chamber V 1 of the front control valve 29.

  The front control valve 29 is a two-position switching valve, and the upper control in FIGS. 1 and 2 is based on the force relationship between the hydraulic signal acting on the driving chamber V1 and the spring S2 provided on the side facing the driving chamber V1. The position is switched between the position (A circuit) and the lower position (B circuit).

  Specifically, when the oil passage 26 becomes a high pressure, the relationship between the drive chamber V1 and the spring S2 becomes V1> S2 and is switched to the A circuit against the force of the spring S2, so that the groove 5 The communicated oil passage 30 communicates with a drive chamber SV3 (described later) of the stroke control valve 25 through the oil passage 31. Further, when the oil passage 26 becomes low pressure, V1 <S2 and the spring S2 is used to switch to the B circuit, whereby the drive chamber SV3 is communicated with the oil passage 32 communicated with the tank T through the oil passage 31. The drive chamber SV3 is guided to a low pressure.

  The stroke control valve 25 is a two-position switching type valve. The upper position (A circuit) and the lower position in FIGS. 1 and 2 are actuated by the hydraulic signal communicating with the drive chambers SV1, SV2 and SV3 and the action of the spring S1. (B circuit).

  Specifically, when the stroke control valve 25 is the A circuit, the oil passage 33 communicated with the brake chamber 15 is communicated with the oil passage 34 communicated with the drive chamber SV1 and the oil passage 35 communicated with the groove 8. Is communicated with the oil passage 24.

  When the stroke control valve 25 is a B circuit, the oil passage 34 is communicated with an oil passage 36 communicated with the tank T, and the drive chamber SV1 is at a low pressure.

  An oil passage 37 communicating with the groove 7 is communicated with the drive chamber SV2 of the stroke control valve 25, and the oil passage 37 and the oil passage 24 are communicated with each other by an oil passage 39 provided with a check valve 38. ing.

  The drive chambers SV1, SV2 and SV3 are configured so that each hydraulic signal acts according to each situation as will be described later, and the force of the spring S1 is also set. Is configured to hold at a switching position corresponding to each situation.

  In addition, the code | symbol 20a in FIG. 2 is the switching valve switched by the operation pedal etc. which were interposed by the oil path 20. FIG.

  Next, the operation of the striking device 1 will be described together with details such as the switching operation of each valve based on each hydraulic signal.

  First, each valve immediately after the working fluid is introduced from the hydraulic pump P to the impacting device 1 is arranged in the following state.

  In the control valve 21, the drive chamber CV 1 is connected to the tank T through the oil passages 24, 39, 37, the groove 7, and the groove 6 through the oil passage 13 to be low pressure, and the drive chamber CV 2 is high pressure through the oil passage 22. Therefore, it is in the state of A circuit.

  The front control valve 29 is in a B circuit by the force of the spring S2, and the drive chamber SV3 is set to a low pressure by communicating the drive chamber SV3 of the stroke control valve with the tank T through the oil passage 32.

  The stroke control valve 25 is also a B circuit by the force of the spring S1.

  When the working fluid is introduced from the hydraulic pump P in a state where the valves are arranged as described above, the pressure oil is introduced from the groove 9 into the accommodating chamber 11 through the oil passages 20 and 23. Thereby, a high pressure is applied to the pressure receiving surface PS2 of the large-diameter portion 2b, and the striking piston 2 performs a return stroke that moves to the left in FIG. 1 while compressing the gas sealed in the gas chamber C3.

  Thus, when the return stroke is performed and the pressure receiving surface PS2 of the large diameter portion 2b is retracted to the position where the groove 9 communicates with the groove 8, high pressure is introduced from the groove 8 to the oil passage 35, but the passage 35 becomes a B circuit. Since the stroke control valve 25 is shut off, the striking piston 2 continues the return stroke.

  When the pressure receiving surface PS2 of the large-diameter portion 2b moves backward to a position where the groove 9 communicates with the groove 7, a high pressure is introduced from the groove 7 through the oil passage 37 to the drive chamber SV2 of the stroke control valve 25. As a result, the stroke control valve 25 switches from the B circuit to the A circuit against the force of the spring S1. By switching the stroke control valve 25 to the A circuit in this way, the high pressure introduced from the groove 8 into the oil passage 35 is introduced into the drive chamber CV1 of the control valve 21 through the oil passage 24, and the drive chambers CV1 and CV2 are connected to each other. Since the relationship is preset as CV1> CV2, the control valve 21 is switched from the A circuit to the B circuit.

  Accordingly, the working fluid from the hydraulic pump P is introduced from the groove 9 into the accommodation chamber 11 through the oil passage 23 and is also introduced into the accommodation chamber 10 from the groove 4 through the oil passage 26. As a result, since the pressure receiving surface is in a relationship of PS1> PS2, the striking piston 2 is switched to a striking stroke in which it moves to the right in FIG.

  On the other hand, since a high pressure is also introduced into the driving chamber V1 of the front control valve 29 through the oil passage 28, the front control valve 29 is switched to the A circuit against the force of the spring S2. Thus, although the groove 5 communicates with the drive chamber SV3 of the stroke control valve 25 through the oil passages 30 and 31, the groove 5 is accommodated by the striking piston 2 in the housing chamber 10 in the initial state when the striking piston 2 has shifted to the striking stroke. The high pressure introduced into the storage chamber 10 is not introduced into the drive chamber SV3.

  The groove 7 and the groove 6 are communicated with each other through the annular groove 12 immediately before the striking piston 2 performing the striking stroke strikes the chisel 3. As a result, the oil passage 37 is opened to a low pressure through the oil passage 13. For this reason, the drive chamber CV1 of the control valve 21 becomes a low pressure through the oil passages 24, 39, 37, the grooves 7, 6 and the oil passage 13, whereby the control valve 21 is switched to the A circuit by the high pressure acting on the drive chamber CV2. Start dividing. At the same time, the driving chamber SV2 is also at a low pressure, but SV1> SV3 + spring S1 force is set, and the stroke control valve 25 holds the A circuit.

  However, at this time, the striking piston 2 is sufficiently accelerated in the striking direction, and strikes the chisel 3 before the control valve 21 is switched to the A circuit.

  On the other hand, the groove 5 that has been closed substantially simultaneously with the communication between the groove 7 and the groove 6 described above communicates with the groove 4 through the storage chamber 10, and from the groove 5 through the front control valve 29 of the A circuit and the oil passage 31, Is introduced into the drive chamber SV3 of the stroke control valve 25. At this time, in the stroke control valve 25, there is a force relationship between the drive chambers SV1, 2, 3 and the spring S1 in advance so that the A circuit is maintained without switching to the B circuit even when a normal high pressure is applied to the drive chamber SV3. Since it is set, the stroke control valve 25 holds the A circuit.

  By the way, when the chisel 3 hits the hitting object as described above, the stroke of the return stroke until the hitting piston 2 shifts to the next hitting stroke varies depending on the hardness of the hitting object as follows.

  First, the case where a hit | damage target object is hard is demonstrated.

  In this case, when the chisel 3 hits the hit object, the chisel 3 does not bite into the hit object. When the chisel 3 is not displaced as described above, the striking piston 2 is not displaced further in the striking direction of the chisel 3 and the theoretical striking position (regular striking position) L as shown in FIG. become.

  At this time, the impact force transmitted to the chisel 3 by the striking piston 2 is reflected at a large ratio from the striking object, and a large force in the returning direction is returned to the striking piston 2 through the chisel 3. For this reason, the striking piston 2 changes its direction of movement in a very short time and starts the return stroke. However, the working fluid applied to the pressure receiving surface PS2 of the striking piston 2 still maintains the movement toward the oil passage 23 through the groove 9, while the working fluid applied to the pressure receiving surface PS1 of the striking piston 2 maintains the movement in the striking direction. doing. For this reason, the pressure acting on the pressure receiving surface PS1 increases rapidly, and the pressure acting on the pressure receiving surface PS2 is reduced.

  Such a pressure state is transmitted from the groove 5 to the drive chamber SV3 of the stroke control valve 25 through the oil passage 30, the front control valve 29, and the oil passage 31 in the storage chamber 10, and in the storage chamber 11, a brake is applied. It is transmitted from the chamber 15 to the drive chamber SV1 of the stroke control valve 25 through the passage 33, the stroke control valve 25, and the oil passage 34.

  As a result, when the force of the drive chamber SV3 + spring S1 and the force of the drive chamber SV1 are reversed, the stroke control valve 25 is switched to the B circuit. At this time, the oil in the drive chamber SV1 is returned to the oil passage 23 through the oil passage 39a and the check valve 38a, and the oil in the drive chamber SV2 returns to the tank T through the grooves 7 and 6. Thus, in the state where the stroke control valve 25 is switched to the B circuit, the drive chamber SV1 is communicated with the tank T through the oil passage 34 and the oil passage 36 and kept at a low pressure, and the oil passages 26 and 28 are at a low pressure. Since the front control valve 29 is switched to the B circuit by the spring S2, the driving chamber SV3 is also at a low pressure. Therefore, the stroke control valve 25 is held in the B circuit by the force of the spring S1 until a high pressure is applied to the drive chamber SV2.

  Thus, since the stroke control valve 25 is switched to the B circuit, the oil passage 35 is blocked even if the pressure receiving surface PS2 of the large diameter portion 2b returns to the position where the groove 9 communicates with the groove 8. Therefore, there is no transition to the striking stroke. Therefore, the return stroke is continued and the pressure receiving surface PS2 of the large diameter portion 2b is retracted to the position where the groove 9 communicates with the groove 7, and high pressure is introduced from the groove 7 into the drive chamber SV2 of the stroke control valve 25 through the oil passage 37. As a result, the stroke control valve 25 switches from the B circuit to the A circuit against the force of the spring S1. When the stroke control valve 25 is switched to the A circuit, the high pressure introduced from the groove 8 into the oil passage 35 is introduced into the drive chamber CV1 of the control valve 21 through the oil passage 24, and the control valve 21 is changed from the A circuit to the B circuit. The striking piston 2 is switched to the striking stroke.

  That is, when the hit object is hard and the chisel 3 does not bite into the hit object, the so-called long stroke S2 (see FIG. 3) in which the pressure receiving surface PS2 of the large diameter portion 2b returns to the groove 7 and shifts to the hitting stroke. The operation will be repeated.

  Next, when the chisel 3 bites into the hit object when hitting the chisel 3 with the hit piston 2 because the hit object is soft or broken even with a hard hit object, Operation is performed.

  In this case, the impact energy of the striking piston 2 is used for crushing the striking object through the chisel 3, and the reaction is hardly returned to the striking piston 2. Therefore, the striking piston 2 does not rebound, but waits for the control valve 21 to switch to the B circuit and starts the return stroke.

  For this reason, the pressure fluctuation applied to the pressure receiving surface PS1 and the pressure receiving surface PS2 of the striking piston 2 is not so large that the stroke control valve 25 is switched to the B circuit as in the case where the striking object is hard. Remains the A circuit.

  Therefore, when the pressure receiving surface PS2 of the large diameter portion 2b returns to the position where the groove 9 communicates with the groove 8, a high pressure is introduced from the groove 8 through the oil passage 35 through the oil passage 24 to the drive chamber CV1, and the control valve 21 is set to B. The circuit is switched to this, so that the striking piston 2 starts its striking stroke from this position.

  That is, when the hit object is soft, the operation of the so-called short stroke S1 (see FIG. 3) in which the pressure receiving surface PS2 of the large diameter portion 2b returns to the groove 8 and shifts to the hitting stroke is repeated. That is, although the energy at the time of impact is smaller than that of the long stroke S2 due to the short stroke S1, the work amount can be increased by increasing the number of impacts, and as a result, impact efficiency can be increased.

  In this way, by switching the stroke control valve 25 based on the change in the pressure state applied to the pressure receiving surface PS1 and the pressure receiving surface PS2 when the chisel 3 is hit with the hitting piston 2, the next hitting stroke is changed to the short stroke S1. And the long stroke S2 can be automatically changed.

  Further, the striking piston 2 is stroke controlled by switching the control valve 21 by switching the stroke control valve 25 while holding the switching position of the stroke control valve 25 by the holding mechanism provided in the hydraulic circuit. The stroke control can be performed efficiently and accurately. The check valve 38 is provided in order to ensure the switching order of the control valve 21 and the stroke control valve 25, but may be replaced with a passage restriction that performs the same function.

[Second Embodiment]
FIG. 4 shows another circuit configuration in the hydraulic striking device of the present invention. In addition, the same code | symbol is attached | subjected about the structure similar to the structure demonstrated in the said 1st Embodiment, and description is abbreviate | omitted.

  This hydraulic striking device is provided with a stroke control valve 50 in which the holding mechanism incorporated in the above-described stroke control valve is separated as a holding valve 40, and the striking stroke has two or more stages (four stages in this example). To be able to choose.

  Hereinafter, the holding valve 40, the stroke control valve 50, and other oil passage configurations will be described with reference to FIG.

  In the stroke control valve 50, the spool 51 is axially moved in the axial direction (left-right direction in FIG. ) For a predetermined amount.

  The drive chamber SV1 communicates with the brake chamber 15 through the oil passage 52, the drive chamber SV2 communicates with one port of the front control valve 60 through the oil passage 53, and the other port of the front control valve 60 is connected to the oil passage 53. The groove 5 communicates with the groove 5.

  The front control valve 60 is a two-position switching valve, and is provided on the side facing the drive chamber V1 and a hydraulic signal that acts on the drive chamber V1 via an oil passage 55 branched from the oil passage 54. The position is switched between the upper position (A circuit) and the lower position (B circuit) in FIGS. 4 and 5 depending on the force relationship with the spring S4.

  Specifically, when the oil passage 55 becomes high pressure, the relationship between the drive chamber V1 and the spring S4 becomes V1> S4, and the B circuit is switched against the force of the spring S4. The communicating oil passage 54 communicates with the drive chamber SV2 through the oil passage 53. Further, when the oil passage 55 becomes low pressure, V1 <S4 is established, and the force is switched to the A circuit by the force of the spring S4, whereby the oil passage 53 is communicated with the oil passage 56 communicated with the tank T, and the drive chamber SV2. Is led to low pressure.

  On the other hand, four lock grooves 57a, 57b, 57c, 57d are formed at equal intervals on one end portion side (drive chamber SV1 side) of the spool 51.

  The holding valve 40 is for engaging with any one of the lock grooves 57a to 57d as the spool 51 moves to hold the spool 51 in that position.

  Specifically, for example, in a state where the lock groove 57b is locked as shown in FIG. 5, an annular lock chamber 41 is arranged facing the periphery of the lock groove 57b. 42 is communicated through the insertion hole 43. On the other hand, the valve main body 42 is provided with a piston 44, and a lock pin 45 protrudes from one end surface of the piston 44 so as to pass through the insertion hole 43.

  The valve body 42 is connected to an oil passage 46 branched from the oil passage 26 on the lock pin 45 side, and a spring S5 is provided on the opposite side of the lock pin 45 with the piston 44 interposed therebetween.

  Therefore, when the oil passage 46 is at a low pressure, the lock pin 45 is moved to the lock groove side by the force of the spring S5, and the tip 45a of the lock pin 45 is engaged with, for example, the lock groove 57b disposed opposite thereto. Stop and hold the spool 51. Further, when the oil passage 46 is at a high pressure, the lock pin 45 moves toward the valve main body 42 against the force of the spring S5 and disengages from the lock groove 57b or the like, so that the spool 51 is free to move.

  As shown in FIG. 6, a groove 45b is formed in the middle of the lock pin 45, and when the tip 45a of the lock pin 45 is locked to the lock groove 57b or the like as described above, The lock chamber 41 communicates with the oil passage 47 communicated with the tank T through the insertion hole 43 through the groove 45b.

  The lock chamber 41 communicates with the oil passage 55 through an oil passage 48 as shown in FIG. As a result, as described above, when the lock pin 45 is locked in the lock groove 57b or the like, the fluid in the drive chamber V1 of the front control valve 60 is released to the tank T. That is, in a state where the lock is effective, the driving chamber V1 is at a low pressure, and the front control valve 60 is in the A circuit.

  Further, annular grooves 58 and 59 are formed on the other end side of the spool 51 at a predetermined interval, and these grooves 58 and 59 are communicated by a communication hole 70 formed in the spool 51. Yes.

  The groove 58 communicates with the groove 7 through the oil passage 71 and communicates with the drive chamber CV <b> 1 of the control valve 21 through the oil passage 72.

  The groove 59 is one of the oil passages 73, 74, 75 communicated with the grooves 8, 8a, 8b formed in the cylinder chamber C1 when the spool 51 is moved and held by the holding valve 40. It is designed to communicate with two oil passages.

  That is, the interval between the communicating portions of the oil passages 73, 74, 75 communicating with the spool 51 is set to be the same as the interval between the centers of the lock grooves 57a to 57d. For example, the groove 59 communicates with the passage 75 when the lock pin 45 is engaged with the lock groove 57a, and the groove 59 communicates with the passage 73 when the lock pin 45 is engaged with the lock groove 57c. .

  On the other hand, the groove 58 communicates with the oil passages 71 and 72 even when the groove 59 is not in communication with any of the oil passages 73, 74, and 75 with the lock pin 45 engaged with the lock groove 57d. The width is set large.

  Next, the operation of the impact device 1 configured as described above will be described.

  First, when the stroke control valve 50 is in a state where the lock pin 45 of the holding valve 40 is engaged with the lock groove 57b as shown in FIGS. 4 and 5, the working fluid is introduced from the hydraulic pump P. At this time, the control valve 21 is in the A circuit state because the drive chamber CV2 is at a high pressure through the oil passage 22 while the drive chamber CV1 is at a low pressure, and the front control valve 60 is in the drive chamber V1. Since the pressure is low as described above, the circuit is in the A circuit state.

  When the working fluid is introduced in a state where the valves are arranged as described above, the pressure oil is introduced from the groove 9 into the accommodating chamber 11 through the oil passages 20 and 23. Thereby, a high pressure acts on the pressure receiving surface PS2 of the large-diameter portion 2b, and the striking piston 2 performs a return stroke that moves to the left in FIGS. 4 and 5 while compressing the gas sealed in the gas chamber C3.

  When the pressure receiving surface PS2 of the large-diameter portion 2b moves backward to a position where the groove 9 communicates with the groove 8a, the control valve 21 is driven from the groove 8a through the oil passage 74, the groove 59, the communication hole 70, the groove 58, and the oil passage 72. High pressure is introduced into the chamber CV1. As a result, the control valve 21 is switched to the B circuit, and the striking piston 2 shifts to the striking stroke.

  During this striking stroke, a high pressure is introduced into the holding valve 40 through the passages 26 and 46, and the piston 44 moves backward against the force of the spring S5 by this action, so that the lock pin 45 is engaged with the lock groove 57b. Is released and the spool 51 becomes free. At this time, the front control valve 60 is still in the A circuit because the groove 5 is closed from communicating with the storage chamber 10 by the striking piston 2. At this time, the communication between the lock chamber 41 and the low-pressure oil passage 47 is blocked by the tip 45a of the lock pin 45.

  The groove 7 and the groove 6 are communicated with each other through the annular groove 12 immediately before the striking piston 2 performing the striking stroke strikes the chisel 3. As a result, the drive chamber CV1 of the control valve 21 is opened to a low pressure through the oil passage 71, the groove 58 of the spool 51, and the oil passage 72, and the control valve 21 starts to be switched to the A circuit by the high pressure acting on the drive chamber CV2.

  However, at this time, the striking piston 2 is sufficiently accelerated in the striking direction, and strikes the chisel 3 before the control valve 21 is switched to the A circuit.

  On the other hand, the groove 5 that has been closed substantially simultaneously with the communication between the groove 7 and the groove 6 described above communicates with the groove 4 and the storage chamber 10, and from the groove 5 to the drive chamber V 1 of the front control valve 60 through the oil passage 54. High pressure is introduced. As a result, the front control valve 60 is switched to the B circuit.

  By the way, when the chisel 3 hits the hitting object as described above, the stroke of the return stroke until the hitting piston 2 shifts to the next hitting stroke varies depending on the hardness of the hitting object as follows. It is controlled by the stroke control valve 50.

  First, the case where a hit | damage target object is hard is demonstrated.

  In this case, when the chisel 3 hits the hit object, the chisel 3 does not bite into the hit object. Thus, when the chisel 3 is not displaced, the striking piston 2 is not displaced further in the striking direction of the chisel 3, and the theoretical striking position (regular striking position) L as shown in FIG. become.

  At this time, the impact force transmitted to the chisel 3 by the striking piston 2 is reflected at a large ratio from the striking object, and a large force in the returning direction is returned to the striking piston 2 through the chisel 3. For this reason, the striking piston 2 changes its direction of movement in a very short time and starts the return stroke. However, the working fluid applied to the pressure receiving surface PS2 of the striking piston 2 still maintains the movement toward the oil passage 23 through the groove 9, while the working fluid applied to the pressure receiving surface PS1 of the striking piston 2 maintains the movement in the striking direction. doing. For this reason, the pressure acting on the pressure receiving surface PS1 increases rapidly, and the pressure acting on the pressure receiving surface PS2 is reduced.

  Such a pressure state is transmitted from the groove 5 to the drive chamber SV2 of the stroke control valve 50 through the oil path 54, the B circuit front control valve 60, and the oil path 53 in the storage chamber 10, and also to the storage chamber 11. Is transmitted from the brake chamber 15 through the passage 52 to the drive chamber SV1 of the stroke control valve 50. The fluid once entering the drive chamber SV2 through the oil passage 54 is not affected because the piston 2 closes the groove 5 in accordance with the timing when the control valve 21 switches to the A circuit.

  As a result, the spool 51 largely moves from the high-pressure drive chamber SV2 side to the left side in FIGS. 4 and 5 against the force of the spring S3 from the low-pressure drive chamber SV1 side.

  Immediately after this, the stopper pin 45 of the holding valve 40 moves so as to protrude toward the spool 51 side because the oil passages 26 and 46 become low pressure by switching the control valve 21 to the A circuit.

  The movement of the stopper pin 45 causes the lock chamber 41 to communicate with the tank T through the groove 45b, the insertion hole 43, and the oil passage 47 of the stopper pin 45 as shown in FIG. The fluid is released to the tank T through the oil passage 48, the lock chamber 41, and the like. As a result, the front control valve 60 is switched to the A circuit by the force of the spring S4, and the spool 51 is moved in the direction of action (right side in FIGS. 4 and 5) by the action of the drive chamber SV1 and the spring S3. By this movement, for example, the front end 45a is locked in the lock groove 57d disposed adjacent to the front end 45a of the stopper pin 45, and the spool 51 is held.

  As a result, only the groove 7 communicates with the drive chamber CV1 of the control valve 21 through the oil passage 71, the groove 58 of the spool 51, and the oil passage 72, and the grooves 8, 8a and 8b are disconnected from the groove 59 of the spool 51. It becomes a state.

  Accordingly, when the striking piston 2 performs the return stroke in a state where the spool 51 is disposed at the position described above, the return stroke is performed until the pressure receiving surface PS2 of the large diameter portion 2b reaches the position where the groove 9 communicates with the groove 7. The high pressure is introduced into the drive chamber CV1 from the groove 7 and the control valve 21 is switched to the B circuit, so that the striking piston 2 shifts to the striking stroke. In other words, the striking stroke in this case is longer than the state in which the stopper pin 45 is locked in the lock groove 57b and the spool 51 is fixed, and the striking stroke strikes a hard striking object with a large impact energy. become.

  On the other hand, when the object is soft, the impact energy of the striking piston 2 is used for crushing the striking object through the chisel 3, and the reaction is hardly returned to the striking piston 2. Therefore, the pressure fluctuation applied to the pressure receiving surface PS1 and the pressure receiving surface PS2 of the striking piston 2 becomes smaller than the height difference as in the case where the striking object is hard.

  Therefore, the spool 51 moves based on the force relationship between the driving chamber SV1 + spring S3 and the driving chamber SV2 due to the difference in pressure generated according to the softness of the hit object, and the stopper pin 45 is locked into the locking grooves 57a to 57c. The next stroke is determined based on the position of the spool 51.

  For example, when the stopper pin 45 is locked in the lock groove 57a, the groove 8b is in communication with the drive chamber CV1 through the oil passage 75, the groove 59, the communication hole 70, the groove 58, and the oil passage 72, and as a result. After the pressure receiving surface PS2 of the large diameter portion 2b performs the return stroke to the position where the groove 9 communicates with the groove 8b, the stroke shifts to the striking stroke. That is, the striking stroke is performed with the minimum stroke.

  Thus, at the time of striking with the striking piston 2, the next striking stroke is determined based on the difference between the pressure in the accommodating chamber 10 acting on the pressure receiving surface PS1 and the pressure in the accommodating chamber 11 acting on the pressure receiving surface PS2. In the example, it can be automatically controlled in four stages.

  Thereby, it is possible to automatically change the striking stroke to efficiently crush the striking object during the striking operation.

  Further, if the multi-stage stroke control as described above can be performed, even if it is necessary to crush the hitting object fairly finely, the crushing can be performed using a large hitting device, which is very useful.

  In this example, the striking piston 2 is stroke controlled in four stages. However, the stroke control is not limited to four stages, and can be two stages, three stages, or four stages or more. In this case, the number of lock grooves in the spool 51 and the number of grooves in the cylinder chamber C1 may be provided in accordance with the number of stages to be stroke controlled.

It is a figure showing the whole hydraulic hitting device composition of the present invention. It is an enlarged view which similarly shows the circuit structure of a hydraulic striking device. It is a figure for demonstrating the stroke by a striking piston. It is a figure which shows the other whole structure of the hydraulic striking device of this invention. It is an enlarged view which similarly shows the circuit structure of a hydraulic striking device. It is an enlarged view which shows the holding state of the spool by a holding valve.

Explanation of symbols

1 striking device 2 striking piston 3 chisel 10 accommodation room (upper room)
11 Containment room (lower room)
25 Stroke control valve 29 Front control valve 40 Holding valve (holding mechanism)
50 Stroke control valve 51 Spool 60 Front control valve

Claims (3)

In the hydraulic hitting device that hits the chisel by reciprocating the hitting piston,
A stroke control valve that is switched based on the pressure difference between the upper and lower chambers of the striking piston when the striking target is hit,
A holding mechanism for holding the stroke control valve in its switching position,
A hydraulic striking device characterized in that the next striking stroke is controlled in at least two stages based on the switching position of the stroke control valve.   A front control valve is provided that communicates the chamber above the striking piston and the drive chamber of the stroke control valve at the time of hitting the hitting object, and applies a hydraulic signal from the upper chamber to the drive chamber. The hydraulic striking device according to claim 1.   The hydraulic striking device according to claim 1, wherein the holding mechanism includes a holding valve that holds a spool of a stroke control valve at each moving position.

Images