US20160053541A1 - Hydraulically Striking Device - Google Patents
Hydraulically Striking Device Download PDFInfo
- Publication number
- US20160053541A1 US20160053541A1 US14/829,824 US201514829824A US2016053541A1 US 20160053541 A1 US20160053541 A1 US 20160053541A1 US 201514829824 A US201514829824 A US 201514829824A US 2016053541 A1 US2016053541 A1 US 2016053541A1
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- Prior art keywords
- port
- piston
- valve
- hydraulic fluid
- striking device
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- Abandoned
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- 239000012530 fluid Substances 0.000 claims abstract description 117
- 238000005553 drilling Methods 0.000 claims description 15
- 239000011435 rock Substances 0.000 claims description 15
- 238000004891 communication Methods 0.000 claims description 9
- 230000008878 coupling Effects 0.000 claims description 9
- 238000010168 coupling process Methods 0.000 claims description 9
- 238000005859 coupling reaction Methods 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 5
- 230000000903 blocking effect Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 239000010720 hydraulic oil Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000009527 percussion Methods 0.000 description 1
- 238000005293 physical law Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
Images
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B4/00—Drives for drilling, used in the borehole
- E21B4/06—Down-hole impacting means, e.g. hammers
- E21B4/14—Fluid operated hammers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D17/00—Details of, or accessories for, portable power-driven percussive tools
- B25D17/06—Hammer pistons; Anvils ; Guide-sleeves for pistons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
- B25D9/06—Means for driving the impulse member
- B25D9/12—Means for driving the impulse member comprising a built-in liquid motor, i.e. the tool being driven by hydraulic pressure
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B1/00—Percussion drilling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2217/00—Details of, or accessories for, portable power-driven percussive tools
- B25D2217/0011—Details of anvils, guide-sleeves or pistons
- B25D2217/0019—Guide-sleeves
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25D—PERCUSSIVE TOOLS
- B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
- B25D2250/231—Sleeve details
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B1/00—Percussion drilling
- E21B1/12—Percussion drilling with a reciprocating impulse member
- E21B1/24—Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure
- E21B1/26—Percussion drilling with a reciprocating impulse member the impulse member being a piston driven directly by fluid pressure by liquid pressure
Definitions
- the present invention relates to a hydraulically striking device and components used for striking on a material hydraulically for example in rock drilling or similar applications.
- a hydraulically striking device comprises a piston that hydraulically reciprocates between a first position and a second position.
- the movement is controlled hydraulically with a controlling arrangement which is in connection with the device.
- the controlling arrangement may include a valve, for example inside the device and the connections to the piston.
- Hydraulically striking devices are used in the hydraulic machines that are, for example, working in rock drilling or similar applications.
- Rock drilling is usually performed in mines and construction plants. In some of the mining plants, it is not uncommon that they can produce hundreds of thousands of tons of ore from the rock in a year.
- the hydraulically striking device is also used for drilling and sampling, general excavations, tunneling work and roof bolting. On the work site, the hydraulically striking device can be used for drilling of rock.
- One example of test results of one rock drilling equipment working on the drilling site shows typical operating values of the machine equipped with one model-size hydraulically striking device, such as a penetration rate of around 2 meters/minute in granite with a drill hole diameter of around 50 mm when using a percussion pressure from around 100 bar up to 200-300 bar.
- a penetration rate of around 2 meters/minute in granite with a drill hole diameter of around 50 mm when using a percussion pressure from around 100 bar up to 200-300 bar.
- a penetration rate of around 2 meters/minute in granite with a
- a controlling arrangement such as a valve is provided inside the hydraulically striking device and is designed to last in the hard working environment of the machine.
- the valve is usually larger than a standard-size screw-in cartridge valve, robust and strongly built, as the hydraulically striking device can strike generally from 30 to 100 times in a second.
- the device can weigh up to hundreds of kilos. But in the future, bigger and heavier models are needed when the demands from the industry rise. Also, demands for a higher striking force with lower flows raise the demands for the equipment so that the operating pressures of the hydraulically striking device can be at a relatively high level.
- a common problem is that the hydraulic fluid controlling the piston does not change completely or the amount of hydraulic fluid changed is insignificant in the controlling arrangement.
- the hydraulic fluid for example hydraulic oil, vibrates back and forth between the piston and the controlling arrangement and creates cavitation that damages the device and the whole hydraulic system.
- the cavitating fluid causes the air bubbles in the fluid to explode rapidly, further mechanically removing particles such as metal chips from the structure. This may destroy the components in contact with the fluid.
- the reciprocating movement causes the fluid to move back and forth and the fluid between the piston and the control arrangement does not change.
- the fluid being essentially in the same position is more likely to wear the structures in use. Cavitation occurs especially when there is no adequate circulation of the hydraulic fluid.
- the temperature of the hydraulic fluid in these segments of the hydraulic circuit reaches a higher level than normal. Fluid that is at a higher temperature than normal is more likely to cavitate.
- a substantial amount of air is usually trapped in the hydraulic circuit. After the startup, it is essential to remove the air from the circuit of the device. If the trapped air is not removed, it will be mixed to the hydraulic fluid which leads to easier cavitation.
- the air in the device also causes delay in the operation of the valve as the air is compressible. Cavitation also occurs in situations where a substantially low pressure hydraulic fluid flows with substantially high flow rate from the device to the tank, particularly when the flow suddenly stops.
- the objective of the invention is to eliminate or at least alleviate the problems mentioned above and introduce solutions for them.
- a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston.
- a first control channel and a second control channel extend from the valve, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, and wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
- the flow leads in essentially one direction, for example only in one direction or sequentially in one direction.
- a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston, where the valve is provided with a moving member.
- a first control channel and a second control channel extend from the valve, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port and to the second port, wherein the location of one or more flow spaces in the piston allows one of the control channels to be blocked while the moving member of the valve moves and receives or delivers hydraulic fluid.
- the cylinder body is formed of one or more parts.
- the piston comprises one flow space, which is a uniform groove between a first edge and a second edge of the flow space, wherein the edges act as closing surfaces of the flow of the hydraulic fluid.
- the piston comprises a first portion and a second portion, wherein the flow space is located between the portions.
- the valve is provided in connection with the hydraulically striking device.
- the piston has a first longitudinal center axis and the valve has a second longitudinal center axis, wherein the second longitudinal center axis coincides with the first longitudinal center axis.
- the valve is provided inside the cylinder body. In one embodiment of the invention, the valve is provided outside the cylinder body. In one embodiment of the invention, the valve is for example piped, detachably or fixedly connected with fittings, connected with flexible hoses, bolted as a separate part or connected into the cylinder body as a combination of the methods described above.
- the valve comprises a moving member which is configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position.
- the hydraulic fluid flows into a closed space of the valve and changes the volume of fluid inside the valve by moving the moving member.
- the direction of movement of the piston is changed by the position of the moving member.
- the moving member is a spool or a poppet or a combination of a spool and a poppet of the valve.
- the hydraulically striking device further comprises a third port, a fourth port, a pressure line and a return line, wherein the third port and the fourth port open into the cylinder at different points in the axial direction and at a distance from one another and from the first port and the second port, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port, to the second port, to the third port and to the fourth port, wherein the third port is coupled with the pressure line and the fourth port is coupled with the return line.
- the third port is coupled with the pressure line of the hydraulically striking device so as to move the moving member with the pressure provided by the hydraulic fluid which flows therefrom at times
- the fourth port is coupled with the return line of the hydraulically striking device into which the hydraulic fluid returned by the moving member is allowed to flow at times as the moving member moves back to its initial position.
- the ports mentioned in this paragraph and above in previous paragraphs are arranged to open towards the outer cylindrical surface of the piston.
- the flow space mentioned in this paragraph and above in the first and second paragraph is a recess, one or more grooves, one or more drillings or one or more channels arranged in the surface of the piston.
- these flow space embodiments provide in the selective coupling a space between the piston and the cylinder body for flowing.
- a choke is provided in the fourth port or in the return line.
- the piston in the selective coupling with the piston disposed in the first or second position, is arranged to block the flow communication to at least one of the control channels by blocking the port connected to that control channel.
- the flow space in the first position of the piston, connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel.
- the piston in the second position of the piston, blocks the third port and the flow space connects the first port and the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via both control channels.
- the hydraulic fluid flows in the second control channel in essentially one direction.
- the piston blocks the third port and the first port and the flow space connects the second port to the fourth port, the hydraulic fluid flowing via the second control channel.
- the flow space connects the third port to the first port and to the second port and the piston blocks the fourth port, allowing the hydraulic fluid to flow via both control channels.
- the hydraulic fluid flows in the first control channel in essentially one direction.
- the flow space in the first position of the piston, connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel.
- the piston in the second position of the piston, blocks the third port and the first port and the flow space connects the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via the second control channel.
- the hydraulic fluid flows in both of the control channels in essentially one direction.
- the flow is divided among the channels.
- the first position of the piston is the front position of the piston, wherein the piston is pulled out from the cylinder body and moving towards its extreme position
- the second position of the piston is the back position of the piston, wherein the piston is retracted into the cylinder body and moving towards its extreme position.
- the reciprocating movement of the piston is used for example for drilling rock or for example in applications where a material, for example rock, has to be put into smaller pieces.
- the hydraulically striking device is a rock drilling machine.
- a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston.
- the valve comprises a moving member configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position, a first control channel and a second control channel extending from a closed space of the valve enabling hydraulic fluid to flow to the closed space of the valve and to change the volume of the fluid inside the valve by moving the moving member, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
- the hydraulically striking device described here has many significant advantages comparing to the prior art.
- the fluid flows from the pressure line to the valve and flows back to the tank via another channel.
- This action is achieved by arranging the fluid flow essentially in one direction in one of the control channels when the piston reciprocates back and forth.
- a preferable situation is when the fluid flows in both control channels in essentially one direction when the piston moves back and forth.
- This enables efficient circulation, as most of the fluid flows via the moving member, e.g. a spool, wherein the movement of the spool causes a flow in essentially one direction while the spool reciprocates.
- Both actions flush the valve and simultaneously cool this part of the circuit. Both actions help to prevent cavitation in the system.
- the constantly changing fluid does not wear the structures in use so easily.
- the circulation prevents the possible air pockets formed during the assembly process from being trapped inside for a substantially long time. The fluid in this situation is less subject to cavitation. Most of the air is circulated out from the valve, resulting in a smaller risk of delay or malfunctioning of the valve.
- inventions described herein may be used in any combination with each other. Several or at least two of the embodiments may be combined together to form a further embodiment of the invention.
- a method or a device to which the invention is related may comprise at least one of the embodiments of the invention described hereinbefore.
- FIGS. 1 a - 1 b are simplified schematic illustrations of a hydraulically striking device
- FIGS. 2 a - 2 b are other simplified schematic illustrations of a hydraulically striking device
- FIGS. 4 a - 4 b are illustrations of a cross-section of a simplified hydraulically striking device.
- FIGS. 5 a - 5 b are simplified schematic illustrations of one example of a hydraulically striking device according to prior art.
- FIGS. 1 to 4 are simplified illustrations of different examples of a hydraulically striking device. Due to the simplification in FIGS. 1 a to 3 b and 5 a and 5 b, the cylinder body 1 is only described by two straight horizontal lines, wherein the cylinder 2 is formed between the lines. Due to the simplification in FIGS. 1 a to 3 b and 5 a and 5 b, the valve 6 is described as a small cylinder in fluid communication with the piston 3 . The direction of flow in the circuit of the device is indicated with arrow(s) in FIGS. 1 a to 5 b.
- One example of the hydraulically striking device comprises a cylinder body 1 , wherein the cylinder body 1 forms a cylinder 2 .
- the cylinder body 1 comprises a piston 3 configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder 2 .
- a valve 6 for controlling the movement of the piston 3 .
- a first control channel 7 and a second control channel 8 extend from the valve 6 , a first port 9 and a second port 10 open into the cylinder 2 at different points in the axial direction and at a distance from one another, wherein the first port 9 is coupled to the first control channel 7 and the second port 10 is coupled to the second control channel 8 .
- the piston 3 is provided with at least one flow space 13 for selective coupling of the first port 9 and the second port 10 , allowing the hydraulic fluid which controls the valve 6 in the first control channel 7 and in the second control channel 8 to flow in one of the control channels 7 and 8 in one direction so as to provide circulation of the hydraulic fluid controlling the valve 6 .
- the selective coupling means that the piston 3 selects one of the ports 9 , 10 in either of the positions of the piston to be connected with the flow space 13 .
- the flow leads in essentially one direction, for example only in one direction or sequentially in one direction.
- the cylinder body 1 is formed of one or more parts.
- a first control channel 7 and a second control channel 8 extend from the valve 6 , a first port 9 and a second port 10 open into the cylinder 2 at different points in the axial direction and at a distance from one another, wherein the first port 9 is coupled to the first control channel 7 and the second port 10 is coupled to the second control channel 8 .
- the piston 3 comprises at least one flow space 13 which is arranged to be selectively coupled to the first port 9 and to the second port 10 , wherein the location of one or more flow spaces 13 in the piston 3 allows one of the control channels 7 , 8 to be blocked while the moving member 14 of the valve 6 moves and receives or delivers hydraulic fluid.
- the piston 3 comprises one flow space 13 , which is a uniform groove between a first edge 16 and a second edge 17 of the flow space 13 , wherein the edges 16 , 17 act as closing surfaces of the flow of the hydraulic fluid.
- the piston 3 further comprises a first portion 18 and a second portion 19 , wherein the flow space 13 is located between the portions 18 , 19 .
- valve 6 When the valve 6 is used, it is working in the device or combined to the device, thereby being part of the device.
- the valve 6 is arranged inside the cylinder body 1 as described above. This decreases the number of parts needed in the device and reduces the number of potential leakage points.
- the valve 6 comprises the moving member 14 which moves for a specific distance from its initial position within the valve 6 and takes hydraulic fluid in an amount corresponding to the movement and returns hydraulic fluid when moving back to the initial position.
- the direction of movement of the piston 3 is changed by the position of the moving member 14 .
- the moving member 14 is a spool or a poppet or a combination of a spool and a poppet of the valve 6 .
- the movement of the moving member 14 is operated by feeding hydraulic fluid via a channel 7 , 8 into the valve 6 .
- the hydraulically striking device comprises a third port 11 , a fourth port 12 , a pressure line P and a return line T, wherein the third port 11 and the fourth port 12 open into the cylinder 2 at different points in the axial direction and at a distance from one another and from the first port 9 and the second port 10 , the piston 3 comprising at least one flow space 13 which is arranged to be selectively coupled to the first port 9 , to the second port 10 , to the third port 11 and to the fourth port 12 , wherein the third port 11 is coupled with the pressure line P and the fourth port 12 is coupled with the return line T.
- the third port 11 is coupled with the pressure line P of the hydraulically striking device so as to move the moving member 14 with the pressure provided by the hydraulic fluid which flows therefrom at times
- the fourth port 12 is coupled with the return line T of the hydraulically striking device into which the hydraulic fluid returned by the moving member 14 is allowed to flow at times as the moving member 14 moves back to its initial position.
- the pressure of the pressure line P may act on both sides of the moving member 14 .
- the pressure of the pressure line P acts on both sides of the moving member 14 .
- the area of the moving member 14 is bigger on the side where the control channels 7 , 8 connect to the valve 6 .
- the ports 9 , 10 , 11 , 12 are arranged to open towards the outer cylindrical surface of the piston 3 .
- the flow space 13 is arranged in the selective coupling between the piston 3 and the cylinder body 1 .
- the flow space 13 may be a groove which is arranged rotationally symmetrically in the surface of the piston 3 . Other arrangements to provide the flow space 13 are possible.
- the flow space 13 is for example a groove machined in the axial direction into the surface of the piston 3 , or optionally there may be several grooves around the piston 3 .
- the flow space 13 is formed by one or more holes drilled into the piston 3 or the flow space 13 is formed by one or more channels arranged in the surface of the piston 3 .
- Common for all flow spaces 13 is that they provide a space between the piston 3 and the cylinder body 1 allowing the flowing of hydraulic fluid.
- the piston 3 selects some of the ports 9 , 10 , 11 , 12 in either of the positions of the piston to be connected with the flow space 13 , while some of the ports 9 , 10 , 11 , 12 can be blocked by the piston 3 .
- the choke 15 is provided in the fourth port 12 or in the return line T, reducing the risk of cavitation when the fluid flows to the tank T by restricting the flow and raising the pressure level in the portion of the circuit before the choke 15 .
- the piston 3 In the selective coupling with the piston 3 disposed in the first or second position, the piston 3 is arranged to block the flow communication to at least one of the control channels 7 , 8 by blocking the first port 9 or second port 10 connected to that control channel.
- the flow is divided among the channels 7 , 8 , for example substantially equally among the channels 7 , 8 .
- the piston 3 In the selective coupling with the piston 3 disposed in the first or second position, the piston 3 is arranged to block the flow communication to at least one of the control channels 7 , 8 by blocking the port 9 , 10 connected to that control channel.
- FIGS. 1 a and 1 b illustrate one example of a simplified hydraulically striking device, wherein FIG. 1 a illustrates the first position of the piston 3 and FIG. 1 b the second position of the piston 3 .
- FIG. 1 a illustrates the first position of the piston 3 , wherein the flow space 13 connects the third port 11 to the first port 9 and the piston 3 blocks the second port 10 and the fourth port 12 , allowing the hydraulic fluid to flow via the first control channel 7 .
- Figure lb illustrates the second position of the piston 3 , wherein the piston 3 blocks the third port 11 and the flow space 13 connects the first port 9 and the second port 10 to the fourth port 12 , allowing the hydraulic fluid to flow from the valve 6 via both control channels 7 , 8 .
- the hydraulic fluid flows in the second control channel 8 in one direction.
- FIG. 2 illustrates the second example of a simplified hydraulically striking device, wherein FIG. 2 a illustrates the first position of the piston 3 and FIG. 2 b the second position of the piston 3 .
- the piston 3 blocks the third port 11 and the first port 9 and the flow space 13 connects the second port 10 to the fourth port 12 , the hydraulic fluid flowing via the second control channel 8 .
- the first position of the piston 3 is shown, wherein the flow space 13 connects the third port 11 to the first port 9 and to the second port 10 and the piston 3 blocks the fourth port 12 , allowing the hydraulic fluid to flow via both control channels 7 , 8 .
- the hydraulic fluid flows in the first control channel 7 in one direction.
- FIG. 3 illustrates the third example of a simplified hydraulically striking device, wherein FIG. 3 a illustrates the first position of the piston 3 and FIG. 3 b illustrates the second position of the piston 3 .
- the flow space 13 connects the third port 11 to the first port 9 and the piston 3 blocks the second port 10 and the fourth port 12 , allowing the hydraulic fluid to flow via the first control channel 7 .
- the piston 3 blocks the third port 11 and the first port 9 and the flow space 13 connects the second port 10 to the fourth port 12 , allowing the hydraulic fluid to flow from the valve 6 via the second control channel 8 .
- FIGS. 3 a and 3 b in the first and second position of the piston 3 , the hydraulic fluid flows in both of the control channels 7 , 8 in one direction.
- the first position of the piston 3 is the front position of the piston 3 , wherein the piston is pulled out from the cylinder body 1 in proximity to its extreme position
- the second position of the piston 3 is the back position of the piston 3 , wherein the piston 3 is retracted into the cylinder body 1 in proximity to its extreme position.
- proximity to the extreme position of the piston 3 means that the piston 3 is in an approximate position where the piston 3 is substantially near its extreme position but not necessarily fully retracted or pulled out and where the moving member 14 changes its position. This position is difficult to define exactly because the piston 3 is in constant movement, but the position can be e.g. 0.1 to 30 mm apart from the extreme position.
- the reciprocating movement is used for example for drilling rock or for example in applications where a material, for example rock, has to be put into smaller pieces.
- FIGS. 4 a and 4 b illustrate a cross-section of a hydraulically striking device.
- FIG. 4 a illustrates the first position of the piston 3 and FIG. 4 b the second position of the piston 3 .
- the first position of the piston 3 also means here that the piston 3 has moved outwards from the cylinder body 1 to an approximate position substantially near its extreme position.
- the second position also means here that the piston 3 has moved inwards to the cylinder body 1 to an approximate position substantially near its extreme position.
- the operation of the fluid circulation of the hydraulically striking device described in FIGS. 4 a and 4 b is similar to the operation according to FIGS. 1 a and 1 b.
- FIGS. 4 a and 4 b illustrate a more detailed example of a hydraulically striking device and its structures.
- the valve 6 is arranged near the inner end 190 of the piston 3 .
- the inner space 30 in the valve 6 can be in fluid communication with the inner end 190 of the piston 3 .
- the piston 3 is partially inside the valve 6 .
- the piston 3 is arranged partially inside the valve 6 and the moving member 14 .
- the first channel 7 and second channel 8 can be arranged axially inside the cylinder body 1 and on both sides of the piston 3 .
- a first damper 20 is arranged on the first portion 18 of the piston 3 and a second damper 20 a on the second portion 19 of the piston 3 .
- the dampers 20 , 20 a of the piston 3 are arranged on the tank side and the pressure side of the piston 3 .
- dampers 20 , 20 a The purpose of these dampers 20 , 20 a is to dampen and slow down the speed of the piston 3 when it reaches the proximity of its extreme position.
- the surface areas of the dampers 20 , 20 a function as surfaces on which the slowing force of the piston acts.
- the surface areas of the dampers 20 , 20 a are angular surfaces.
- the piston 3 has a first longitudinal center axis 23 and the valve 6 has a second longitudinal center axis 24 , wherein the second longitudinal center axis 24 coincides with the first longitudinal center axis 23 .
- the valve 6 is provided inside the cylinder body 1 and is concentric with the piston 3 in FIGS. 4 a and 4 b , but as explained above, other arrangements are possible.
- the examples described herein may be used for example in a rock drilling machine.
- the circulation of the hydraulic fluid controlling the valve 6 is achieved by arranging the flow so that the fluid flows in essentially one direction through one or both of the control channels 7 , 8 .
- This circulation may be effected by arranging check valves (not shown) into the cylinder body 1 .
- the check valves limit the flow in one direction.
- By adding for example two check valves (not shown) into the channels 7 , 8 between the piston 3 and the valve 6 it is possible to arrange a similar circulation of fluid between the valve 6 and the piston 3 .
- the flow enters the valve 6 via the first check valve and returns from the valve 6 via the second check valve.
- FIGS. 5 a and 5 b illustrate one example of a simplified hydraulically striking device according to prior art.
- the operation of the moving member 14 in FIGS. 5 a and 5 b is similar to the operation described above in FIGS. 1 a to 3 b.
- the reference P represents the pressure line and the reference T the tank line. Hydraulic fluid flows to a closed space in the valve 6 and changes the volume of fluid inside the valve 6 by moving the moving member 14 .
- the direction of flow and the direction of the moving member 14 are described with arrow(s) also in FIGS. 5 a and 5 b .
- the changeover of fluid in the valve 6 depends on the distance of the channels 7 , 8 and the volume of fluid in the channels 7 , 8 relative to the volume of fluid received by the valve 6 .
- the difference between FIGS. 5 a and 5 b representing the prior art is that the fluid changes only at the beginning of the channels 7 , 8 .
- These portions of the channels 7 , 8 are referenced by numbers 21 and 22 . This kind of a feature is not preferred because the fluid does not circulate inside the device and can cause problems such as cavitation.
- FIG. 5 a illustrates the first position of the piston 3
- FIG. 5 b illustrates the second position of the piston 3
- the flow space 13 connects the third port 11 to the first port 9 and to the second port 10 and the piston 3 blocks the fourth port 12 , allowing the hydraulic fluid to flow via both of the control channels 7 , 8
- the piston 3 blocks the third port 11 and the flow space 13 connects the first port 9 and the second port 10 to the fourth port 12 , allowing the hydraulic fluid to flow from the valve 6 via both of the control channels 7 , 8 .
- the fluid flows bi-directionally in both of the control channels 7 , 8 it does not circulate and so it is not changed in the valve 6 .
- This invention is particularly useful in equipment wherein hydraulically striking devices are used in the hydraulic machines that are for example working in the rock drilling or similar applications.
- inventions described herein may be used in any combination with each other. Several or at least two of the embodiments may be combined together to form a further embodiment of the invention.
- a method or a device to which the invention is related may comprise at least one of the embodiments of the invention described hereinbefore.
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Abstract
A hydraulically striking device having a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder. According to the invention, a first control channel and a second control channel extend from the valve, a first port and a second port open into the cylinder, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, the piston having at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
Description
- The present invention relates to a hydraulically striking device and components used for striking on a material hydraulically for example in rock drilling or similar applications.
- One example of a hydraulically striking device comprises a piston that hydraulically reciprocates between a first position and a second position. The movement is controlled hydraulically with a controlling arrangement which is in connection with the device. The controlling arrangement may include a valve, for example inside the device and the connections to the piston.
- Hydraulically striking devices are used in the hydraulic machines that are, for example, working in rock drilling or similar applications. Rock drilling is usually performed in mines and construction plants. In some of the mining plants, it is not uncommon that they can produce hundreds of thousands of tons of ore from the rock in a year. The hydraulically striking device is also used for drilling and sampling, general excavations, tunneling work and roof bolting. On the work site, the hydraulically striking device can be used for drilling of rock. One example of test results of one rock drilling equipment working on the drilling site shows typical operating values of the machine equipped with one model-size hydraulically striking device, such as a penetration rate of around 2 meters/minute in granite with a drill hole diameter of around 50 mm when using a percussion pressure from around 100 bar up to 200-300 bar. On the drill site, around or over 100 mm holes are not uncommon for the rock drilling equipment.
- Usually, a controlling arrangement such as a valve is provided inside the hydraulically striking device and is designed to last in the hard working environment of the machine. The valve is usually larger than a standard-size screw-in cartridge valve, robust and strongly built, as the hydraulically striking device can strike generally from 30 to 100 times in a second.
- The device can weigh up to hundreds of kilos. But in the future, bigger and heavier models are needed when the demands from the industry rise. Also, demands for a higher striking force with lower flows raise the demands for the equipment so that the operating pressures of the hydraulically striking device can be at a relatively high level.
- A common problem is that the hydraulic fluid controlling the piston does not change completely or the amount of hydraulic fluid changed is insignificant in the controlling arrangement. The hydraulic fluid, for example hydraulic oil, vibrates back and forth between the piston and the controlling arrangement and creates cavitation that damages the device and the whole hydraulic system. The cavitating fluid causes the air bubbles in the fluid to explode rapidly, further mechanically removing particles such as metal chips from the structure. This may destroy the components in contact with the fluid. When the fluid does not circulate, the reciprocating movement causes the fluid to move back and forth and the fluid between the piston and the control arrangement does not change.
- The fluid being essentially in the same position is more likely to wear the structures in use. Cavitation occurs especially when there is no adequate circulation of the hydraulic fluid. The temperature of the hydraulic fluid in these segments of the hydraulic circuit reaches a higher level than normal. Fluid that is at a higher temperature than normal is more likely to cavitate. When the device is assembled, a substantial amount of air is usually trapped in the hydraulic circuit. After the startup, it is essential to remove the air from the circuit of the device. If the trapped air is not removed, it will be mixed to the hydraulic fluid which leads to easier cavitation. The air in the device also causes delay in the operation of the valve as the air is compressible. Cavitation also occurs in situations where a substantially low pressure hydraulic fluid flows with substantially high flow rate from the device to the tank, particularly when the flow suddenly stops.
- The objective of the invention is to eliminate or at least alleviate the problems mentioned above and introduce solutions for them.
- According to a first aspect of the invention, there is provided a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston. According to the invention, a first control channel and a second control channel extend from the valve, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, and wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve. The flow leads in essentially one direction, for example only in one direction or sequentially in one direction.
- According to a second aspect of the invention, there is provided a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston, where the valve is provided with a moving member. According to the invention, a first control channel and a second control channel extend from the valve, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port and to the second port, wherein the location of one or more flow spaces in the piston allows one of the control channels to be blocked while the moving member of the valve moves and receives or delivers hydraulic fluid.
- In one embodiment of the invention, the cylinder body is formed of one or more parts. In one embodiment of the invention, the piston comprises one flow space, which is a uniform groove between a first edge and a second edge of the flow space, wherein the edges act as closing surfaces of the flow of the hydraulic fluid. In one embodiment of the invention, the piston comprises a first portion and a second portion, wherein the flow space is located between the portions.
- In one embodiment of the invention, the valve is provided in connection with the hydraulically striking device. In one embodiment of the invention, the piston has a first longitudinal center axis and the valve has a second longitudinal center axis, wherein the second longitudinal center axis coincides with the first longitudinal center axis. In one embodiment of the invention, the valve is provided inside the cylinder body. In one embodiment of the invention, the valve is provided outside the cylinder body. In one embodiment of the invention, the valve is for example piped, detachably or fixedly connected with fittings, connected with flexible hoses, bolted as a separate part or connected into the cylinder body as a combination of the methods described above.
- In one embodiment of the invention, the valve comprises a moving member which is configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position. In one embodiment of the invention, the hydraulic fluid flows into a closed space of the valve and changes the volume of fluid inside the valve by moving the moving member. In one embodiment of the invention, the direction of movement of the piston is changed by the position of the moving member. In one embodiment of the invention, the moving member is a spool or a poppet or a combination of a spool and a poppet of the valve.
- In one embodiment of the invention, the hydraulically striking device further comprises a third port, a fourth port, a pressure line and a return line, wherein the third port and the fourth port open into the cylinder at different points in the axial direction and at a distance from one another and from the first port and the second port, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port, to the second port, to the third port and to the fourth port, wherein the third port is coupled with the pressure line and the fourth port is coupled with the return line. In one embodiment of the invention, the third port is coupled with the pressure line of the hydraulically striking device so as to move the moving member with the pressure provided by the hydraulic fluid which flows therefrom at times, and the fourth port is coupled with the return line of the hydraulically striking device into which the hydraulic fluid returned by the moving member is allowed to flow at times as the moving member moves back to its initial position. In one embodiment of the invention, the ports mentioned in this paragraph and above in previous paragraphs are arranged to open towards the outer cylindrical surface of the piston. In one embodiment of the invention, the flow space mentioned in this paragraph and above in the first and second paragraph is a recess, one or more grooves, one or more drillings or one or more channels arranged in the surface of the piston. In one embodiment of the invention, these flow space embodiments provide in the selective coupling a space between the piston and the cylinder body for flowing. In one embodiment, a choke is provided in the fourth port or in the return line.
- In one embodiment of the invention, in the selective coupling with the piston disposed in the first or second position, the piston is arranged to block the flow communication to at least one of the control channels by blocking the port connected to that control channel.
- In one embodiment of the invention, in the first position of the piston, the flow space connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel. In one embodiment of the invention, in the second position of the piston, the piston blocks the third port and the flow space connects the first port and the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via both control channels. In one embodiment of the invention, in the first and second position of the piston, the hydraulic fluid flows in the second control channel in essentially one direction.
- In one embodiment of the invention, in the second position of the piston, the piston blocks the third port and the first port and the flow space connects the second port to the fourth port, the hydraulic fluid flowing via the second control channel. In one embodiment of the invention, in the first position of the piston, the flow space connects the third port to the first port and to the second port and the piston blocks the fourth port, allowing the hydraulic fluid to flow via both control channels. In one embodiment of the invention, in the first and second position of the piston, the hydraulic fluid flows in the first control channel in essentially one direction.
- In one embodiment of the invention, in the first position of the piston, the flow space connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel. In one embodiment of the invention, in the second position of the piston, the piston blocks the third port and the first port and the flow space connects the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via the second control channel. In one embodiment of the invention, in the first and second position of the piston, the hydraulic fluid flows in both of the control channels in essentially one direction.
- In one embodiment of the invention, when the first control channel and the second control channel are provided in flow communication, the flow is divided among the channels.
- In one embodiment of the invention, the first position of the piston is the front position of the piston, wherein the piston is pulled out from the cylinder body and moving towards its extreme position, and the second position of the piston is the back position of the piston, wherein the piston is retracted into the cylinder body and moving towards its extreme position. In one embodiment of the invention, the reciprocating movement of the piston is used for example for drilling rock or for example in applications where a material, for example rock, has to be put into smaller pieces. In one embodiment of the invention, the hydraulically striking device is a rock drilling machine.
- According to a third aspect of the invention, there is provided a hydraulically striking device comprising a cylinder body, the cylinder body forming a cylinder therein, a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and a valve for controlling the movement of the piston. According to the invention the valve comprises a moving member configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position, a first control channel and a second control channel extending from a closed space of the valve enabling hydraulic fluid to flow to the closed space of the valve and to change the volume of the fluid inside the valve by moving the moving member, a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
- The hydraulically striking device described here has many significant advantages comparing to the prior art. When the hydraulic fluid controlling the valve circulates, the fluid flows from the pressure line to the valve and flows back to the tank via another channel. This action is achieved by arranging the fluid flow essentially in one direction in one of the control channels when the piston reciprocates back and forth. A preferable situation is when the fluid flows in both control channels in essentially one direction when the piston moves back and forth. This enables efficient circulation, as most of the fluid flows via the moving member, e.g. a spool, wherein the movement of the spool causes a flow in essentially one direction while the spool reciprocates.
- Both actions flush the valve and simultaneously cool this part of the circuit. Both actions help to prevent cavitation in the system. The constantly changing fluid does not wear the structures in use so easily. The circulation prevents the possible air pockets formed during the assembly process from being trapped inside for a substantially long time. The fluid in this situation is less subject to cavitation. Most of the air is circulated out from the valve, resulting in a smaller risk of delay or malfunctioning of the valve.
- This hydraulically striking device has a choke in the fourth port or in the return line. This feature enables preventing or alleviating cavitation even more in the circuit. The choke restricts the flow of the fluid returning to the tank and creates a back pressure that raises the pressure level. The choke reduces the risk of cavitation in a substantially low pressure fluid.
- The embodiments of the invention described herein may be used in any combination with each other. Several or at least two of the embodiments may be combined together to form a further embodiment of the invention. A method or a device to which the invention is related may comprise at least one of the embodiments of the invention described hereinbefore.
- The above embodiments or modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives.
- The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:
-
FIGS. 1 a-1 b are simplified schematic illustrations of a hydraulically striking device; -
FIGS. 2 a-2 b are other simplified schematic illustrations of a hydraulically striking device; -
FIGS. 3 a-3 b are other simplified schematic illustrations of a hydraulically striking device; -
FIGS. 4 a-4 b are illustrations of a cross-section of a simplified hydraulically striking device; and -
FIGS. 5 a-5 b are simplified schematic illustrations of one example of a hydraulically striking device according to prior art. - Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
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FIGS. 1 to 4 are simplified illustrations of different examples of a hydraulically striking device. Due to the simplification inFIGS. 1 a to 3 b and 5 a and 5 b, the cylinder body 1 is only described by two straight horizontal lines, wherein thecylinder 2 is formed between the lines. Due to the simplification inFIGS. 1 a to 3 b and 5 a and 5 b, thevalve 6 is described as a small cylinder in fluid communication with thepiston 3. The direction of flow in the circuit of the device is indicated with arrow(s) inFIGS. 1 a to 5 b. - One example of the hydraulically striking device comprises a cylinder body 1, wherein the cylinder body 1 forms a
cylinder 2. The cylinder body 1 comprises apiston 3 configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in thecylinder 2. In connection with the device there is arranged avalve 6 for controlling the movement of thepiston 3. Afirst control channel 7 and asecond control channel 8 extend from thevalve 6, afirst port 9 and asecond port 10 open into thecylinder 2 at different points in the axial direction and at a distance from one another, wherein thefirst port 9 is coupled to thefirst control channel 7 and thesecond port 10 is coupled to thesecond control channel 8. Thepiston 3 is provided with at least oneflow space 13 for selective coupling of thefirst port 9 and thesecond port 10, allowing the hydraulic fluid which controls thevalve 6 in thefirst control channel 7 and in thesecond control channel 8 to flow in one of thecontrol channels valve 6. The selective coupling means that thepiston 3 selects one of theports flow space 13. The flow leads in essentially one direction, for example only in one direction or sequentially in one direction. The cylinder body 1 is formed of one or more parts. - Another example of the hydraulically striking device comprises a cylinder body 1, wherein the cylinder body 1 forms a
cylinder 2. The cylinder body 1 comprises apiston 3 configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in thecylinder 2. In connection with the hydraulically striking device there is arranged avalve 6 for controlling the movement of thepiston 3, where thevalve 6 is provided with a movingmember 14. Afirst control channel 7 and asecond control channel 8 extend from thevalve 6, afirst port 9 and asecond port 10 open into thecylinder 2 at different points in the axial direction and at a distance from one another, wherein thefirst port 9 is coupled to thefirst control channel 7 and thesecond port 10 is coupled to thesecond control channel 8. Thepiston 3 comprises at least oneflow space 13 which is arranged to be selectively coupled to thefirst port 9 and to thesecond port 10, wherein the location of one ormore flow spaces 13 in thepiston 3 allows one of thecontrol channels member 14 of thevalve 6 moves and receives or delivers hydraulic fluid. - In these examples, the
piston 3 comprises oneflow space 13, which is a uniform groove between a first edge 16 and asecond edge 17 of theflow space 13, wherein theedges 16, 17 act as closing surfaces of the flow of the hydraulic fluid. Thepiston 3 further comprises afirst portion 18 and asecond portion 19, wherein theflow space 13 is located between theportions - The
valve 6 is provided in connection with the hydraulically striking device. Thevalve 6 can be arranged inside or outside the cylinder body 1. In one exemplary embodiment, thevalve 6 is arranged outside the cylinder body 1. In this embodiment, thevalve 6 is connected to the cylinder body 1 and into co-operation with the piston by other means, for example by connection points arranged into the cylinder body 1 for thevalve 6. For example, thevalve 6 may be piped, detachably or fixedly connected with fittings, connected with flexible hoses into the cylinder body 1. In one example, a hydraulic manifold is machined for thevalve 6 where thevalve 6 may be installed, and afterwards this manifold may be mounted with bolts into the cylinder body 1. This connection may be made in combination of the previously mentioned connections. When thevalve 6 is used, it is working in the device or combined to the device, thereby being part of the device. In one example, thevalve 6 is arranged inside the cylinder body 1 as described above. This decreases the number of parts needed in the device and reduces the number of potential leakage points. - The
valve 6 comprises the movingmember 14 which moves for a specific distance from its initial position within thevalve 6 and takes hydraulic fluid in an amount corresponding to the movement and returns hydraulic fluid when moving back to the initial position. The direction of movement of thepiston 3 is changed by the position of the movingmember 14. In these examples, the movingmember 14 is a spool or a poppet or a combination of a spool and a poppet of thevalve 6. The movement of the movingmember 14 is operated by feeding hydraulic fluid via achannel valve 6. - In these examples, the hydraulically striking device comprises a
third port 11, afourth port 12, a pressure line P and a return line T, wherein thethird port 11 and thefourth port 12 open into thecylinder 2 at different points in the axial direction and at a distance from one another and from thefirst port 9 and thesecond port 10, thepiston 3 comprising at least oneflow space 13 which is arranged to be selectively coupled to thefirst port 9, to thesecond port 10, to thethird port 11 and to thefourth port 12, wherein thethird port 11 is coupled with the pressure line P and thefourth port 12 is coupled with the return line T. In one example, thethird port 11 is coupled with the pressure line P of the hydraulically striking device so as to move the movingmember 14 with the pressure provided by the hydraulic fluid which flows therefrom at times, and thefourth port 12 is coupled with the return line T of the hydraulically striking device into which the hydraulic fluid returned by the movingmember 14 is allowed to flow at times as the movingmember 14 moves back to its initial position. - The pressure of the pressure line P may act on both sides of the moving
member 14. InFIGS. 1 a to 4 a, the pressure of the pressure line P acts on both sides of the movingmember 14. The area of the movingmember 14 is bigger on the side where thecontrol channels valve 6. This enables inFIGS. 1 a to 4 a that, when the same pressure of the pressure line P acts on both sides of the movingmember 14, which is indicated in theFIGS. 1 a to 4 a with the reference P on both sides of the moving member, the force created on the side of thecontrol channels member 14 and the moving member moves (left) in the direction indicated with an arrow. Respectively, inFIGS. 1 b to 4 b, when the tank line T is connected on the side of thecontrol channels member 14, the movingmember 14 moves by the pressure of the pressure line P towards (right) in the direction indicated with an arrow. One of thecontrol channels member 14 of thevalve 6 moves and, depending on the needed direction of the movement of thepiston 3, receives or delivers hydraulic fluid. Hydraulic fluid flows to aclosed space 130 of thevalve 6 and changes the volume of the fluid inside thevalve 6 by moving the movingmember 14. - The
ports piston 3. Theflow space 13 is arranged in the selective coupling between thepiston 3 and the cylinder body 1. Theflow space 13 may be a groove which is arranged rotationally symmetrically in the surface of thepiston 3. Other arrangements to provide theflow space 13 are possible. Theflow space 13 is for example a groove machined in the axial direction into the surface of thepiston 3, or optionally there may be several grooves around thepiston 3. In one example, theflow space 13 is formed by one or more holes drilled into thepiston 3 or theflow space 13 is formed by one or more channels arranged in the surface of thepiston 3. Common for allflow spaces 13 is that they provide a space between thepiston 3 and the cylinder body 1 allowing the flowing of hydraulic fluid. By selective coupling, thepiston 3 selects some of theports flow space 13, while some of theports piston 3. Thechoke 15 is provided in thefourth port 12 or in the return line T, reducing the risk of cavitation when the fluid flows to the tank T by restricting the flow and raising the pressure level in the portion of the circuit before thechoke 15. - In the selective coupling with the
piston 3 disposed in the first or second position, thepiston 3 is arranged to block the flow communication to at least one of thecontrol channels first port 9 orsecond port 10 connected to that control channel. When thefirst control channel 7 and thesecond control channel 8 are arranged in flow communication, the flow is divided among thechannels channels - In the selective coupling with the
piston 3 disposed in the first or second position, thepiston 3 is arranged to block the flow communication to at least one of thecontrol channels port -
FIGS. 1 a and 1 b illustrate one example of a simplified hydraulically striking device, whereinFIG. 1 a illustrates the first position of thepiston 3 andFIG. 1 b the second position of thepiston 3.FIG. 1 a illustrates the first position of thepiston 3, wherein theflow space 13 connects thethird port 11 to thefirst port 9 and thepiston 3 blocks thesecond port 10 and thefourth port 12, allowing the hydraulic fluid to flow via thefirst control channel 7. Figure lb illustrates the second position of thepiston 3, wherein thepiston 3 blocks thethird port 11 and theflow space 13 connects thefirst port 9 and thesecond port 10 to thefourth port 12, allowing the hydraulic fluid to flow from thevalve 6 via bothcontrol channels piston 3, the hydraulic fluid flows in thesecond control channel 8 in one direction. -
FIG. 2 illustrates the second example of a simplified hydraulically striking device, whereinFIG. 2 a illustrates the first position of thepiston 3 andFIG. 2 b the second position of thepiston 3. In the second position of thepiston 3, thepiston 3 blocks thethird port 11 and thefirst port 9 and theflow space 13 connects thesecond port 10 to thefourth port 12, the hydraulic fluid flowing via thesecond control channel 8. InFIG. 2 a, the first position of thepiston 3 is shown, wherein theflow space 13 connects thethird port 11 to thefirst port 9 and to thesecond port 10 and thepiston 3 blocks thefourth port 12, allowing the hydraulic fluid to flow via bothcontrol channels piston 3, the hydraulic fluid flows in thefirst control channel 7 in one direction. -
FIG. 3 illustrates the third example of a simplified hydraulically striking device, whereinFIG. 3 a illustrates the first position of thepiston 3 andFIG. 3 b illustrates the second position of thepiston 3. In the first position of thepiston 3, theflow space 13 connects thethird port 11 to thefirst port 9 and thepiston 3 blocks thesecond port 10 and thefourth port 12, allowing the hydraulic fluid to flow via thefirst control channel 7. In the second position of thepiston 3, thepiston 3 blocks thethird port 11 and thefirst port 9 and theflow space 13 connects thesecond port 10 to thefourth port 12, allowing the hydraulic fluid to flow from thevalve 6 via thesecond control channel 8. InFIGS. 3 a and 3 b in the first and second position of thepiston 3, the hydraulic fluid flows in both of thecontrol channels - In all examples, the first position of the
piston 3 is the front position of thepiston 3, wherein the piston is pulled out from the cylinder body 1 in proximity to its extreme position, and the second position of thepiston 3 is the back position of thepiston 3, wherein thepiston 3 is retracted into the cylinder body 1 in proximity to its extreme position. In proximity to the extreme position of thepiston 3 means that thepiston 3 is in an approximate position where thepiston 3 is substantially near its extreme position but not necessarily fully retracted or pulled out and where the movingmember 14 changes its position. This position is difficult to define exactly because thepiston 3 is in constant movement, but the position can be e.g. 0.1 to 30 mm apart from the extreme position. The changing of the position of the movingmember 14 of thevalve 6 requires some time, and after the changing of the position of the movingmember 14, thepiston 3 continues its movement because of the inertia of thepiston 3. Because of this physical law, the change of locations where the movingmember 14 changes its position is not necessarily exactly to the extreme positions of thepiston 3. - In some applications, the reciprocating movement is used for example for drilling rock or for example in applications where a material, for example rock, has to be put into smaller pieces.
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FIGS. 4 a and 4 b illustrate a cross-section of a hydraulically striking device.FIG. 4 a illustrates the first position of thepiston 3 andFIG. 4 b the second position of thepiston 3. The first position of thepiston 3 also means here that thepiston 3 has moved outwards from the cylinder body 1 to an approximate position substantially near its extreme position. The second position also means here that thepiston 3 has moved inwards to the cylinder body 1 to an approximate position substantially near its extreme position. The operation of the fluid circulation of the hydraulically striking device described inFIGS. 4 a and 4 b is similar to the operation according toFIGS. 1 a and 1 b.FIGS. 4 a and 4 b illustrate a more detailed example of a hydraulically striking device and its structures. - The
valve 6 is arranged near theinner end 190 of thepiston 3. Theinner space 30 in thevalve 6 can be in fluid communication with theinner end 190 of thepiston 3. Thepiston 3 is partially inside thevalve 6. As thevalve 6 and the movingmember 14 have a hollow inside, thepiston 3 is arranged partially inside thevalve 6 and the movingmember 14. Thefirst channel 7 andsecond channel 8 can be arranged axially inside the cylinder body 1 and on both sides of thepiston 3. Afirst damper 20 is arranged on thefirst portion 18 of thepiston 3 and asecond damper 20 a on thesecond portion 19 of thepiston 3. Thedampers piston 3 are arranged on the tank side and the pressure side of thepiston 3. The purpose of thesedampers piston 3 when it reaches the proximity of its extreme position. The surface areas of thedampers dampers - The
piston 3 has a firstlongitudinal center axis 23 and thevalve 6 has a secondlongitudinal center axis 24, wherein the secondlongitudinal center axis 24 coincides with the firstlongitudinal center axis 23. This means that thepiston 3 and the movingmember 14 of thevalve 6 move along the same axis of movement. - The
valve 6 is provided inside the cylinder body 1 and is concentric with thepiston 3 inFIGS. 4 a and 4 b, but as explained above, other arrangements are possible. - The examples described herein may be used for example in a rock drilling machine. The circulation of the hydraulic fluid controlling the
valve 6 is achieved by arranging the flow so that the fluid flows in essentially one direction through one or both of thecontrol channels channels piston 3 and thevalve 6, it is possible to arrange a similar circulation of fluid between thevalve 6 and thepiston 3. In this example, the flow enters thevalve 6 via the first check valve and returns from thevalve 6 via the second check valve. -
FIGS. 5 a and 5 b illustrate one example of a simplified hydraulically striking device according to prior art. The operation of the movingmember 14 inFIGS. 5 a and 5 b is similar to the operation described above inFIGS. 1 a to 3 b. Similarly as above, the reference P represents the pressure line and the reference T the tank line. Hydraulic fluid flows to a closed space in thevalve 6 and changes the volume of fluid inside thevalve 6 by moving the movingmember 14. The direction of flow and the direction of the movingmember 14 are described with arrow(s) also inFIGS. 5 a and 5 b. The changeover of fluid in thevalve 6 depends on the distance of thechannels channels valve 6. The difference betweenFIGS. 5 a and 5 b representing the prior art is that the fluid changes only at the beginning of thechannels channels numbers -
FIG. 5 a illustrates the first position of thepiston 3 andFIG. 5 b illustrates the second position of thepiston 3. In the first position of thepiston 3, theflow space 13 connects thethird port 11 to thefirst port 9 and to thesecond port 10 and thepiston 3 blocks thefourth port 12, allowing the hydraulic fluid to flow via both of thecontrol channels piston 3, thepiston 3 blocks thethird port 11 and theflow space 13 connects thefirst port 9 and thesecond port 10 to thefourth port 12, allowing the hydraulic fluid to flow from thevalve 6 via both of thecontrol channels control channels valve 6. - This invention is particularly useful in equipment wherein hydraulically striking devices are used in the hydraulic machines that are for example working in the rock drilling or similar applications.
- It is understood that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.
- The embodiments of the invention described herein may be used in any combination with each other. Several or at least two of the embodiments may be combined together to form a further embodiment of the invention. A method or a device to which the invention is related may comprise at least one of the embodiments of the invention described hereinbefore.
- It is to be understood that any of the above embodiments or modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives.
Claims (20)
1. A hydraulically striking device comprising
a cylinder body, the cylinder body forming a cylinder therein,
a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and
a valve for controlling the movement of the piston, wherein
a first control channel and a second control channel extend from the valve,
a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another,
wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel, and
wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
2. The hydraulically striking device according to claim 1 , characterized in that the piston comprises one flow space, which is a uniform groove between a first edge and a second edge of the flow space, wherein the edges act as closing surfaces of the flow of the hydraulic fluid.
3. The hydraulically striking device according to claim 1 , wherein the valve comprises a moving member which is configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position.
4. The hydraulically striking device according to claim 1 , wherein the hydraulically striking device further comprises a third port, a fourth port, a pressure line and a return line, wherein the third port and the fourth port open into the cylinder at different points in the axial direction and at a distance from one another and from the first port and the second port, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port, to the second port, to the third port and to the fourth port, wherein the third port is coupled with the pressure line and the fourth port is coupled with the return line.
5. The hydraulically striking device according to claim 4 , wherein a choke is provided in the fourth port or in the return line.
6. The hydraulically striking device according to claim 3 , wherein the direction of movement of the piston is changed by the position of the moving member.
7. The hydraulically striking device according to claim 3 , wherein the moving member is a spool or a poppet or a combination of a spool and a poppet of the valve.
8. The hydraulically striking device according to claim 1 , wherein in the selective coupling with the piston disposed in the first or in the second position, the piston is arranged to block the flow communication to at least one of the control channels by blocking the port connected to that control channel.
9. The hydraulically striking device according to claim 1 , wherein in the first position of the piston, the flow space connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel.
10. The hydraulically striking device according to claim 9 , wherein in the second position of the piston, the piston blocks the third port and the flow space connects the first port and the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via both control channels.
11. The hydraulically striking device according to claim 1 , wherein in the second position of the piston, the piston blocks the third port and the first port and the flow space connects the second port to the fourth port, the hydraulic fluid flowing via the second control channel.
12. The hydraulically striking device according to claim 11 , wherein in the first position of the piston, the flow space connects the third port to the first port and to the second port and the piston blocks the fourth port, allowing the hydraulic fluid to flow via both control channels.
13. The hydraulically striking device according to claim 1 , wherein in the first position of the piston, the flow space connects the third port to the first port and the piston blocks the second port and the fourth port, allowing the hydraulic fluid to flow via the first control channel.
14. The hydraulically striking device according to claim 13 , wherein in the second position of the piston, the piston blocks the third port and the first port and the flow space connects the second port to the fourth port, allowing the hydraulic fluid to flow from the valve via the second control channel.
15. The hydraulically striking device according to claim 1 , wherein when the first control channel and the second control channel are provided in flow communication, the flow is divided among the channels.
16. The hydraulically striking device according to claim 1 , wherein the piston has a first longitudinal center axis and the valve has a second longitudinal center axis, wherein the second longitudinal center axis coincides with the first longitudinal center axis.
17. The hydraulically striking device according to claim 1 , wherein the hydraulically striking device is a rock drilling machine.
18. The hydraulically striking device according to claim 2 , wherein the valve comprises a moving member configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position.
19. The hydraulically striking device according to claim 2 , wherein the hydraulically striking device further comprises a third port, a fourth port, a pressure line and a return line, wherein the third port and the fourth port open into the cylinder at different points in the axial direction and at a distance from one another and from the first port and the second port, the piston comprising at least one flow space which is arranged to be selectively coupled to the first port, to the second port, to the third port and to the fourth port, wherein the third port is coupled with the pressure line and the fourth port is coupled with the return line.
20. A hydraulically striking device comprising
a cylinder body, the cylinder body forming a cylinder therein,
a piston in the cylinder body, configured to move by means of a hydraulic fluid so as to reciprocate between a first and a second position in the cylinder, and
a valve for controlling the movement of the piston, wherein the valve comprises
a moving member configured to move for a specific distance from its initial position within the valve and to take hydraulic fluid in an amount corresponding to the movement and to return hydraulic fluid when moving back to the initial position,
a first control channel and a second control channel extending from a closed space of the valve enabling hydraulic fluid to flow to the closed space of the valve and to change the volume of the fluid inside the valve by moving the moving member,
a first port and a second port open into the cylinder at different points in the axial direction and at a distance from one another, wherein the first port is coupled to the first control channel and the second port is coupled to the second control channel,
wherein the piston comprises at least one flow space which is arranged to be selectively coupled to the first port and to the second port and allowing the hydraulic fluid which controls the valve in the first control channel and in the second control channel to flow in one of the control channels in one direction so as to provide circulation of the hydraulic fluid controlling the valve.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP14181371.7 | 2014-08-19 | ||
EP14181371.7A EP2987945B1 (en) | 2014-08-19 | 2014-08-19 | Hydraulic striking device |
Publications (1)
Publication Number | Publication Date |
---|---|
US20160053541A1 true US20160053541A1 (en) | 2016-02-25 |
Family
ID=51383578
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/829,824 Abandoned US20160053541A1 (en) | 2014-08-19 | 2015-08-19 | Hydraulically Striking Device |
Country Status (3)
Country | Link |
---|---|
US (1) | US20160053541A1 (en) |
EP (1) | EP2987945B1 (en) |
CN (1) | CN105370656B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20230018715A1 (en) * | 2020-01-08 | 2023-01-19 | Hyundai Everdigm Corporation | Hydraulic breaker |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5056606A (en) * | 1989-06-06 | 1991-10-15 | Eimco-Secoma (Societe Anonyme) | Damped hammer drill |
US5715897A (en) * | 1993-12-13 | 1998-02-10 | G-Drill Ab | In-hole rock drilling machine with a hydraulic impact motor |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4172411A (en) * | 1976-06-09 | 1979-10-30 | Mitsui Engineering & Shipbuilding Co., Ltd. | Hydraulic hammer |
DE69024978T2 (en) * | 1990-07-12 | 1996-12-12 | G Drill Ab | STONE DRILLING DEVICE WITH HYDRAULIC DRIVE IN THE HOLE HOLE |
KR940005811B1 (en) * | 1992-01-15 | 1994-06-23 | 주식회사 수산중공업 | Hydropneumatic hammer |
SE526252C2 (en) * | 2003-03-26 | 2005-08-09 | Wassara Ab | Hydraulic drill string device |
US6799641B1 (en) * | 2003-06-20 | 2004-10-05 | Atlas Copco Ab | Percussive drill with adjustable flow control |
CN2813870Y (en) * | 2005-08-12 | 2006-09-06 | 李和平 | Hydraulic impacting and boring double-function rock drilling machine |
CN102094577B (en) * | 2010-12-09 | 2013-05-29 | 刘国经 | Core valve jet-suction hydraulic down-the-hole (DTH) hammer |
-
2014
- 2014-08-19 EP EP14181371.7A patent/EP2987945B1/en active Active
-
2015
- 2015-08-19 CN CN201510511859.3A patent/CN105370656B/en active Active
- 2015-08-19 US US14/829,824 patent/US20160053541A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5056606A (en) * | 1989-06-06 | 1991-10-15 | Eimco-Secoma (Societe Anonyme) | Damped hammer drill |
US5715897A (en) * | 1993-12-13 | 1998-02-10 | G-Drill Ab | In-hole rock drilling machine with a hydraulic impact motor |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20230018715A1 (en) * | 2020-01-08 | 2023-01-19 | Hyundai Everdigm Corporation | Hydraulic breaker |
Also Published As
Publication number | Publication date |
---|---|
EP2987945A1 (en) | 2016-02-24 |
EP2987945B1 (en) | 2018-01-31 |
CN105370656B (en) | 2018-01-02 |
CN105370656A (en) | 2016-03-02 |
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