Striking device and method for controlling said striking device

Abstract

Hydraulic striking device and method for controlling the working cycle of a striking piston. A rock cutting machine (1, 41) comprises a striking device (4) equipped with a reciprocating piston (9) performing a working cycle (WC). The operation is controlled by a control unit (CU) which generates control signals (CS) for independently operable supply valves (FV) and discharge valves (DV) of a hydraulic system (HS). The position of the piston is detected by a sensing device (S).

Description

[Technical Field]

[0001] The present invention relates to a percussion device equipped with a percussion piston that is supported by bearings so as to be axially movable within a frame of the percussion device.

[0002] The invention further relates to a method for controlling the working cycle of a piston of a striking device.

[0003] The field of the invention is more particularly defined in the preambles of the independent claims. [Background technology]

[0004] A crushing hammer is used to crush hard materials such as rocks, concrete, etc. The crushing hammer comprises a striking device for generating an impact pulse on a crushing tool connectable to the crushing hammer. The striking device comprises a piston, which is axially movably arranged inside a frame of the striking device. The piston moves in an impact direction and a return direction, thereby performing a working cycle during a striking operation. The working cycle is controlled by a valve configured to supply and release pressurized hydraulic fluid prevailing in a working pressure space of the striking device. However, known solutions for controlling the working cycle of the piston present several drawbacks. Summary of the Invention

[0005] SUMMARY OF THE INVENTION It is an object of the present invention to provide a new and improved striking device and method for controlling its operation.

[0006] The striking device according to the invention is characterized by the features characteristic of the independent device claims.

[0007] The method according to the invention is characterized by the features characterizing the independent method claim.

[0008] The disclosed solution concept is to control the working cycle of the percussion device under the control of a control unit. The hydraulic system of the percussion device comprises one or more supply valves and one or more discharge valves that can be controlled independently of each other, and further the control can be implemented steplessly. The control of the valves includes a redundant control feature, where the supply valves and the discharge valves can be in the same control state, i.e. the supply valves and the discharge valves can be simultaneously both open or alternatively closed. The percussion device is designed for rock crushing machines and is implemented in such machines at mining and construction sites.

[0009] More specifically, the solution concept is a hydraulic percussion device comprising a frame and a piston arranged within the frame, the piston configured to perform a work cycle including reciprocating longitudinal movement of the piston in an impact direction and a return direction due to the pressure of hydraulic fluid supplied to first and second working pressure spaces of the percussion device. One or more sensing devices are present for detecting the position of the piston relative to the frame. One or more control units are configured to control one or more supply valves and one or more discharge valves for controlling the supply and discharge of hydraulic fluid to at least one of the first and second pressure spaces to perform the work cycle in response to sensing data received from at least one sensing device and control parameters input to the control unit. The supply valves and discharge valves are controllable into a closed control state and an open control state. Furthermore, the control unit is provided with at least one control cycle, in which the mentioned supply valves and discharge valves are independently controllable. The control cycle includes at least one overlapping control feature, in which the supply valve and the discharge valve are simultaneously in the same control state. Furthermore, the overlap control features mentioned are independently controllable in an infinitely variable manner by control signals from the control unit.

[0010] An advantage of the disclosed solution is that the operation of the work cycle of the percussion device is not limited to only fixed timings for closing and opening the control valve. Instead, the disclosed control system can take into account a variety of situations and environments. In other words, the disclosed control is flexible and adaptable. Furthermore, it is easy to update the control cycle by changing the implemented control parameters and by updating the control software. The disclosed new control principle realizes a wide variety of different useful implementations and use cases. Furthermore, the disclosed solution is relatively easy to implement in a variety of rock crushing machines.

[0011] According to one embodiment, the mentioned overlap control feature includes a positive overlap control feature, in which the supply valve and the discharge valve are closed simultaneously. The overlap control feature further includes a negative overlap control feature, in which the supply valve and the discharge valve are open simultaneously. In other words, positive overlap means that the connection to the hydraulic fluid circuit is closed and there is no hydraulic fluid flow between the controlled working pressure space and the hydraulic system. Furthermore, negative overlap means that the free flow of hydraulic fluid in the hydraulic circuit is configured to pass through the working pressure space controlled by the supply valve and the discharge valve.

[0012] According to one embodiment, both the aggressive and passive overlaps mentioned are infinitely adjustable.

[0013] According to one embodiment, the control unit is configured to simultaneously open the supply valve and the discharge valve and to create a free flow of hydraulic fluid through at least one of the first and second pressure spaces, wherein alternating pressures of the hydraulic fluid during the working cycle of the impact device is implemented.

[0014] According to one embodiment, the control unit is configured to detect the position of the piston at least in the impact direction, to open the supply valve and the discharge valve, and, in response to detecting that the piston has exceeded a predetermined distance limit from the impact point designed for the impacting device in the impact direction, to keep the supply valve and the discharge valve simultaneously open to prevent a continuation of the working cycle of the impacting device. In other words, the control unit can protect the impacting device from harmful empty strikes, for example when the rock crushing machine is not supplied with or pressed against the rock with sufficient force.

[0015] In this embodiment, the control unit is equipped with an anti-slip structure, which can prevent the start of the working cycle if the rock crushing machine is not properly pushed against the target to be crushed, while the control device can stop the working cycle during operation if the piston is moved forward from the designed impact point in the impact direction.

[0016] According to one embodiment, the position of the piston is detected by an on / off type switch that functions as the mentioned sensing device. The switch may be configured to detect a shoulder, edge, groove, or any other discontinuity on the piston.

[0017] According to one embodiment, the piston may be equipped with a special shoulder, edge or groove designed for the detection of a switch or any other type of sensing device.

[0018] According to one embodiment, a sensing device is configured to continuously detect the position of the piston over its entire stroke length during the working cycle.

[0019] According to one embodiment, the position of the piston is detected by a non-contact sensing device, which may be an inductive proximity sensor, an optical sensor, an electrical transmitter / receiver, or the sensing device may be based on magnetism, laser, radio signals, electromagnetic forces, or any other physical phenomenon.

[0020] According to one embodiment, the control unit is provided with sensory data regarding the characteristics of the hydraulic fluid supplied from the hydraulic system to the impacting device. The control unit is further provided with a limit value for at least one characteristic of the hydraulic fluid. The control unit is further configured to open the supply valve and the discharge valve, and to simultaneously maintain the supply valve and the discharge valve open to prevent the continuation of the work cycle of the impacting device in response to detecting that at least one of the characteristics of the hydraulic fluid exceeds an input limit value. In other words, the control unit can be equipped with an overload prevention structure to protect the impacting device from excessive pressure and overflow of the hydraulic fluid supplied from the hydraulic system of the base machine to the rock crushing machine. Alternatively or additionally, the control unit can be equipped with a prevention structure for insufficient flow and / or pressure. In this case, for example, cavitation can be prevented. Another additional or alternative monitored characteristic may be the temperature of the hydraulic fluid in the hydraulic system. When excessively low or high pressure of the pressurized fluid is detected, the control unit implements a predetermined control measure to set the temperature within an acceptable temperature range.

[0021] According to one embodiment, the control unit is equipped with a hydraulic warm-up arrangement, wherein the control device is configured to open the supply valve and the discharge valve and to simultaneously maintain the supply valve and the discharge valve open to allow a free flow of hydraulic fluid through at least one working pressure space for the purpose of transferring thermal energy from the hydraulic fluid flow to the percussion device. The advantage of the warm-up control feature of the control mode is that the rock crushing machine will operate properly when first prepared for use and further, wear and damage during operation, especially in low temperature environments, can be prevented.

[0022] According to one embodiment, the control unit is equipped with a hydraulic warm-up mechanism, in which the control device is configured to close either the supply valve or the discharge valve to increase the pressure in the hydraulic system, raising its temperature and ultimately discharging it to the tank through the work machine's pressure relief valve. When the work machine's hydraulic fluid is sufficiently warmed, it is allowed to flow through the working pressure space. Thus, the control unit opens the supply valve and the discharge valve only when the hydraulic fluid is sufficiently warmed. This can be referred to as a two-phase warm-up control mode.

[0023] According to one embodiment, the control unit is equipped with a shut-off structure, in which the control device is configured to close the supply valve and the discharge valve and to simultaneously maintain the supply valve and the discharge valve in a closed state to prevent hydraulic fluid flow through at least one controlled working pressure space.

[0024] According to one embodiment, the control unit is configured to detect a magnitude of rebound after a striking action of the piston against the tool in response to detection data received from the at least one sensing device for detecting a position of the piston, and further configured to adjust a magnitude of the overlap control feature in response to the detection data regarding the rebound.

[0025] According to one embodiment, the control unit is configured to determine a rebound ratio. The rebound ratio is determined by comparing the piston impact velocity in the impact direction to the piston rebound velocity in the return direction. The impact velocity and rebound velocity can be determined within the control device in response to position detection data based on one or more sensors or position sensing means. The control unit can adjust the overlap of the supply and discharge valves by increasing or decreasing the overlap. At the lower end of the stroke, i.e., when the piston movement changes from movement in the impact direction to movement in the return direction, if the rock being processed is hard, the valve overlap can be increased, thereby reducing the rebound velocity and recovering hydraulic energy. If the rock material being processed is soft, adjusting the overlap includes decreasing the overlap of the supply and discharge valves. This is beneficial because the piston movement in the return direction due to rebound is not limited by the overlap as it is when processing hard rock, where the rebound velocity increases.

[0026] According to one embodiment, the control unit is configured to adjust the characteristics or control of the overlap by increasing or decreasing the duration of the overlap.

[0027] According to one embodiment, the control unit is configured to adjust the characteristics or control of the overlap by adjusting the timing of the start of the overlap.

[0028] According to one embodiment, the rebound impact energy from the rock returning to the crushing hammers causing the rebound is recovered and stored in at least one pressure accumulator of the rock crushing machine, and then both the supply valve and the release valve are closed to prevent the increased pressure of the pressurized fluid from escaping from the rock crushing machine.

[0029] According to one embodiment, the control unit is configured to determine the above-mentioned rebound ratio in response to the detected position data. The control unit can calculate the rebound energy of the piston and can determine the hardness of the rock in response to the detected data of the rebound. A high rebound velocity of the piston in the return direction compared to the piston velocity in the impact direction indicates a hard rock, while a low rebound velocity relative to the impact velocity indicates a relatively soft rock. The collected data on the hardness of the rock material can be stored in the control unit and transmitted to one or more external electrical devices for multiple uses. The data on the rock material can be used to control the operation of the striking device, for preventive maintenance, and to ensure that the rock crushing machine used is well suited for the task.

[0030] According to one embodiment, the control unit comprises a hydraulic short-circuit structure, in which the control device is configured to open the supply valve and the discharge valve and to simultaneously keep the supply valve and the discharge valve open at or near the turning point of the piston's working cycle when the piston movement changes from the return movement to the impact movement. In other words, the hydraulic short-circuit structure can guide hydraulic fluid to the tank, thereby preventing excessive pressure in the controlled working pressure space. This structure can be implemented as an overload prevention structure.

[0031] According to one embodiment, the control unit comprises a stop structure, wherein the control unit is configured to close the supply and discharge valves and to simultaneously maintain them closed at or near the dead center of the piston's work cycle when the piston travel changes from return to impact. In other words, the stop structure can block hydraulic fluid to and from the controlled work pressure space, and this structure can be used to control the travel length.

[0032] According to one embodiment, the control unit is configured to direct a substantially constant hydraulic fluid pressure into the first working pressure space to move the piston in the return direction, and is configured to supply and discharge hydraulic fluid pressure to and from the second working pressure space, thereby controlling the reciprocating movement of the piston during a work cycle, in other words the percussion device has alternating pressure conditions (high pressure - tank pressure) on the impact side of the piston.

[0033] According to one embodiment, the operating principle of the impact device differs from that disclosed in the previous embodiment. The impact device can alternatively have alternating high pressure-tank pressure conditions effective in the return movement of the piston, and also have a substantially constant high pressure condition pushing the piston in the impact direction. Another alternative is a solution in which the alternating high pressure-tank pressure conditions are controlled during the working cycle.

[0034] According to one embodiment, both the supply valve and the release valve are direct electrically controlled on / off operable valves, in other words the disclosed valve configuration includes direct electrical control.

[0035] According to one embodiment, the supply valve comprises a main supply valve controlled by a pressure signal received from a pilot supply valve. Correspondingly, the release valve comprises a main release valve controlled by a pressure signal received from the pilot release valve. Furthermore, the pilot supply valve and the pilot release valve are independently controlled by a control unit. In other words, the disclosed valve arrangement implements a pilot control system.

[0036] According to one embodiment, the solution relates to a method for controlling the operation of a hydraulic impact device, the method comprising detecting a position of a piston by one or more sensing devices and providing sensory data collected by the sensing devices to one or more control units. The method further comprises controlling at least one supply valve and at least one discharge valve under the control of the control unit, and controlling the supply and discharge of hydraulic fluid to at least one of the first and second pressure spaces of the impact device of the rock crushing machine to perform a work cycle of the piston in response to the received sensory data and control parameters input to the control unit. The supply valve and the discharge valve are both controlled to be in a closed control state and an open control state during the work cycle. Furthermore, the supply valve and the discharge valve are controlled independently of each other, and the control is performed by the control unit during the work cycle. The method further comprises implementing at least one overlapping control feature in the control cycle of the mentioned valve, where the supply valve and the discharge valve are simultaneously in the same control state, i.e., both the supply valve and the discharge valve are simultaneously open or simultaneously closed. A control unit generates control signals for controlling the supply valve and the discharge valve steplessly and independently of one another according to an overlap control feature.

[0037] According to one embodiment, the solution relates to a hydraulic rock crushing hammer equipped with the disclosed striking device, in other words the rock crushing machine referred to is a rock crushing hammer.

[0038] According to one embodiment, the solution relates to a hydraulic rock-cutting machine equipped with the disclosed percussion device. In other words, the rock-breaking machine referred to is a rock-cutting machine. The rock-cutting machine may be a so-called tophammer drilling machine or a down-the-hole (DTH) drilling machine.

[0039] The above disclosed embodiments can be combined to form a desired solution that incorporates the necessary features disclosed.

[0040] Some embodiments are explained in more detail in the accompanying drawings. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a schematic side view showing an excavator equipped with a crushing hammer. FIG. [Figure 2] 1 is a schematic diagram illustrating some of the aspects of the disclosed striking device and its controls. [Figure 3] 1 is a schematic side cross-sectional view of a hydraulic striking device of a rock crushing machine; FIG. [Figure 4] FIG. 1 is a schematic side view illustrating a portion of a striking piston and a sensing device configured to monitor movement of the striking piston. [Figure 5] FIG. 1 is a schematic diagram illustrating some features associated with the control system and control unit of a hydraulic rock crushing machine. [Figure 6] FIG. 1 is a schematic diagram illustrating several control modes utilizing overlapping control features. [Figure 7] 1 is a schematic diagram showing a hydraulic impact device equipped with a pilot control valve system; [Figure 8] 1 is a schematic diagram showing a hydraulic rock-cutting machine equipped with a percussion device according to the disclosed solution; DETAILED DESCRIPTION OF THE INVENTION

[0042] For the sake of clarity, these figures illustrate in a simplified manner some embodiments of the disclosed solution, in which like reference numerals denote like elements.

[0043] FIG. 1 shows a crushing hammer 1 arranged at the free end of a boom 2 of a work machine 3, such as an excavator. Alternatively, the boom 2 can be arranged on any movable or fixed platform of, for example, a crushing device. The crushing hammer 1, which is a type of rock crushing machine, comprises a striking device 4 for generating an impact pulse. The striking device 1 can be pressed by the boom 2 against a material 5 to be crushed, while an impact is generated by the striking device 4 against a tool 6 connected to the crushing hammer 1. The tool 6 transmits the impact pulse to the material 5 to be crushed. The striking device 4 is hydraulic and is therefore connected to the hydraulic system of the work machine 2. The impact pulse is generated in the striking device 4 by a striking piston that is moved back and forth in an impact direction A and a return direction B under the influence of a hydraulic fluid. Furthermore, the striking hammer 1 can comprise a protective casing 7, inside which the striking device 4 can be located. The striking device 4 can comply with the solutions disclosed in this document.

[0044] 2 discloses that the striking piston 9 of the striking device 4 of the hydraulic comminution device 1 is reciprocated in an impact direction A and a return direction B according to a work cycle WC. The movement and position of the piston 9 are detected by one or more sensing devices S or sensors. The work cycle WC is controlled by a control unit CU configured to control one or more supply valves FV and one or more discharge valves DV. Both the supply and discharge valves have two control states: an open control state and a closed control state. The valves may be directly electrically operable valves or, alternatively, the valves may be pilot-controlled valves, as will be disclosed later in FIGS. 3 and 7.

[0045] The control unit CU includes one or more control cycles CC for controlling the valves FV and DV and for generating the control signals required to change the control states of the valves. Because the valves FV and DV are controlled by the control unit CU and because their control is not limited by physical constraints or connections, the valves FV and DV can be independently controlled to be in any of their control states. Furthermore, at least one of the control cycles CC of the control unit CU includes at least one overlap control feature OC. Overlap control OC means that the valves FV and DV are in the same control state (open FV + open DV = negative overlap; closed FV + closed DV = positive overlap). The control unit CU can select the desired overlap feature OC and make adjustments in response to detected sensory data and input control principles.

[0046] The features disclosed in FIG. 2 may also be implemented in many different types of rock mining machines.

[0047] 3 discloses the basic structure of a striking device 4 of a rock crushing machine, such as a rock crushing hammer or a rock cutting machine. The striking device 4 comprises a frame 8, inside which a striking piston 9 is arranged so as to be movable in an impact direction A and a return direction B. The piston 9 comprises a working collar 10 at its midsection. On the side of the collar 10 in the impact direction A there is a first working pressure space 11, and on the side of the collar 10 in the return direction B there is a second working pressure space 12, inside which the pressure of the hydraulic fluid is controlled by a control unit CU. The working pressure spaces 11, 12 are separated from each other by a collar sealing element 13. A clearance 14 or annular gap surrounds the working collar 10, and this clearance 14 is sealed by the collar sealing element 13.

[0048] The piston 9 comprises a first working pressure surface 15 for moving the piston 9 in a return direction B and a second working pressure surface 16 for moving the piston 9 in an impact direction A. The control unit CU is able to alternate the pressure in the second working pressure space 12 by connecting the second pressure space to a tank T or a pressure source PS. The control unit CU is able to connect the first working pressure space 11 to the pressure source for the duration of a working cycle. Because the effective area of ​​the second working pressure surface 16 is greater than the effective area of ​​the first working pressure surface 15, the piston moves in the impact direction A when a higher pressure is supplied to the second working pressure space 12. It is noted that the pressure flow control and the effective area of ​​the working pressure surfaces may be configured and dimensioned in other ways as already mentioned above in this document.

[0049] The striking piston 9 is supported relative to the frame 8 by a first piston bearing 17 and a second piston bearing 18. The first piston bearing 17 and the second piston bearing 18 are separate sleeve-like piston bearing elements 19, 20 that can be axially installed in a central through-opening 21 of the frame 8. The first piston bearing element 19 supports the piston 9 at a lower end portion of the striking device 4, and the second piston bearing element 20 supports it at an upper end portion. The piston bearing elements 19, 20 or bushings are equipped with one or more hydraulic seals 22, 23 for sealing the inner diameter of the opening of the piston bearing elements 19, 20 against the outer diameter of the piston 9. In addition to these seals and sealing sections, the piston bearing elements 19, 20 are provided with bearing portions 24, 25 for slidably supporting both end portions of the piston 9. The piston bearing elements 19, 20 may further comprise end buffer spaces 26, 27 which form closed pressure spaces with the working pressure surfaces 15, 16 when the piston exceeds its nominal stroke length in the impact direction A and in the return direction B. As can be seen, a second working pressure space 12 may be defined between the piston 9 and the second piston bearing element 20. The bearing portion 25 of the second bearing element 20 may be equipped with a dedicated lubrication channel 28 for realizing lubrication from a lubricating fluid source L for the sliding bearing surfaces. Both piston bearing elements 19, 20 may be equipped with dedicated tank channels 29, 30 connected to a tank T and equipped with a throttling device 31.

[0050] The striking piston 9 comprises an impact face 32 facing in an impact direction A, which is configured to perform a striking action against the tool. A rear face 33 of the piston 9 faces in a return direction B and is configured to move inside a gas space 34 of a directly acting pressure accumulator 35. At the end portion of the sealed section of the second piston element 20 there is a gas sealing element 36 for separating the bearing part 25 and the gas space 34 from each other in a fluid-tight manner.

[0051] The position of the striking piston 9 can be detected by a sensing device S. The collected sensing data is transmitted to a control unit CU. The control unit CU can further receive sensing data from one or more sensing devices D, which can be configured to detect, for example, hydraulic fluid properties. An operator OP can communicate with the control unit CU via a user interface UI, thereby inputting control parameters, control commands, and updated computer programs into the control unit CU. The control unit CU is configured to generate control commands for one or more supply valves FV and one or more discharge valves DV connected to the hydraulic system HS. In FIG. 3, the valves FV and DV are electrically operable control valves under the direct control of the control unit CU. The valves FV and DV can be simple on / off type valves. Because a large flow of hydraulic fluid is typically controlled during a work cycle, it is possible to configure two or more parallel supply valves FV and two or more parallel discharge valves DV to ensure rapid control measures.

[0052] 4 discloses a sensing device S that may comprise two sensing units S1 and S2. The first sensing unit S1 may be arranged to monitor the bottom dead center of the piston 9 and may comprise two sensing switches Sa and Sb, while the second sensing unit S2 may be arranged to monitor the top dead center of the piston and may comprise two sensing switches Sc and Sd. Alternatively, the necessary timing measurements of the control cycle may be calculated within the control unit in response to sensing data received from the lower switches Sa, Sb and the upper switches Sc, Sd. The use of simple sensing switches Sa-Sd is advantageous, for example, because of their small size, durability, and low cost.

[0053] The piston 9 can be equipped with a dedicated sensing collar 37, the position of which is detected by the sensing device S.

[0054] 5 discloses several features related to the disclosed control system. A control unit CU comprises one or more processors P, one or more memory devices M, and one or more input-output devices 38. One or more control programs CP can be loaded into the control unit CU. The control programs CP can be stored in the memory devices M and processed in the processors P. The control unit CU can receive sensory data SD from the position sensing device S and the detection device D. Control parameters PA and various limit values ​​LV can also be input to the control unit CU.

[0055] Figure 6 discloses a diagram listing some possible use cases of the disclosed overlap control features. These control situations and use cases have been previously discussed in this document.

[0056] Figure 7 is a simplified illustration of an alternative to the system of directly controlled supply and discharge valves presented in Figure 3. In this document, a hydraulic system HS comprises a main supply valve MFV controlled by a pilot supply valve PFV and a corresponding main discharge valve MDV controlled by a pilot discharge valve PDV. A control unit CU provides electrical control for the pilot control valves PFV and PDV, which provide hydraulic control signals for the main control valves MFV and MDV.

[0057] If desired for any reason, it may also be possible to combine the direct control system disclosed in FIG. 3 and the pilot control system disclosed in FIG. 7 and thereby provide one valve with direct control and one valve with pilot control.

[0058] FIG. 8 shows a rock drilling unit 40 comprising a rock drilling machine 41 movably arranged on a feed beam 42. The rock drilling machine 41 comprises a hydraulic impact device 4 for generating impact pulses transmitted to the rock surface by a tool 6. The tool 6 may comprise one or more drill pipes or drill rods and a drill bit 43 at the distal end of the tool 6. A rotation device 44 is arranged to rotate the tool 6 about its longitudinal axis. At the forward end of the body 45 of the rock drilling machine 41, there may be a flushing fluid housing 46 for supplying flushing fluid through the tool 6 down to the drilled hole to remove drilled debris. The impact device 4 is connected to a hydraulic system HS comprising a control structure and components disclosed herein, controlled under the control of at least one control unit CU. The control unit CU is capable of communicating with a user interface UI, sensors S, and detection devices D, and provides the necessary electrical control signals for the control valves of the hydraulic system HS in the manner disclosed herein.

[0059] It is noted that in Figure 8 a tophammer type drilling machine is disclosed, but the solution can also be implemented in DTH type rock drilling machines, where the striking device is located at the drill bit end of the tool.

[0060] The drawings and the associated description are intended only to illustrate the concept of the invention. The invention may vary in detail within the scope of the claims.

Claims

1. a striking device (4) comprising a frame (8) and a piston (9) arranged inside the frame (8) and configured to perform a working cycle (WC) including a reciprocating longitudinal movement of the piston (9) in an impact direction (A) and a return direction (B) due to the pressure of a hydraulic fluid supplied to a first working pressure space (11) and a second working pressure space (12) of the striking device (4); at least one sensing device (S) for detecting the position of said piston (9) relative to said frame (8); at least one supply valve (FV) and at least one discharge valve (DV) for controlling the supply and discharge of said hydraulic fluid to at least one of the first pressure space (11) and the second pressure space (12); at least one control unit (CU) configured to control the supply valve (FV) and the discharge valve (DV) to perform the work cycle (WC) in response to sensing data (SD) received from the at least one sensing device (S) and control parameters (PA) input to the control unit (CU); Equipped with The supply valve (FV) and the discharge valve (DV) are controllable to a state of overlap control in which they are both closed or a state of overlap control in which they are both open; the control unit (CU) comprises at least one control cycle (CC) by which the supply valve (FV) and the discharge valve (DV) can be independently controlled; said control cycle (CC) includes at least one overlapping control in which said supply valve (FV) and said discharge valve (DV) are simultaneously in the same control state; The overlap control can be independently controlled in a stepless manner by a control signal (CS) of the control unit (CU), the control unit (CU) is configured to determine a rebound ratio by comparing a piston impact velocity in an impact direction to a piston rebound velocity in a return direction in response to detected position data received from the at least one sensing device (S); The control unit (CU) is configured to control a state of the overlap control in response to the determined rebound ratio. A striking device (4) characterized in that

2. The overlap control is a positive overlap control in which the supply valve (FV) and the discharge valve (DV) are closed simultaneously; and Negative overlap control, where the supply valve (FV) and the discharge valve (DV) are open simultaneously The striking device of claim 1 , comprising:

3. the control unit (CU) is configured to simultaneously open the supply valve (FV) and the discharge valve (DV) and to create a free flow of hydraulic fluid through at least one of the first working pressure space (11) and the second working pressure space (12), and alternating hydraulic fluid pressures is performed during the working cycle (WC) of the striking device (4). A striking device according to claim 1 or 2, characterized in that it comprises:

4. the control unit (CU) is configured to detect the position of the piston (9) at least in the impact direction (A), to open the supply valve (FV) and the discharge valve (DV), and, in response to detecting that the piston (9) in the impact direction (A) has exceeded a predetermined distance limit from an impact point designed for the striking device (4), to keep the supply valve (FV) and the discharge valve (DV) simultaneously open in order to prevent the continuation of the work cycle (WC) of the striking device (4). A striking device according to any one of claims 1 to 3, characterized in that it comprises:

5. said control unit (CU) is provided with sensory data (SD) relating to the properties of the hydraulic fluid supplied to said striking device (4) from a hydraulic system (HS); the control unit (CU) is provided with a limit value (LV) for at least one property of the hydraulic fluid; the control unit (CU) is configured to open the supply valve (FV) and the discharge valve (DV) and to simultaneously maintain the supply valve (FV) and the discharge valve (DV) open to prevent continuation of the work cycle (WC) of the impact device (4) in response to detecting that at least one of the characteristics of the hydraulic fluid exceeds an input limit value (LV). A striking device according to any one of claims 1 to 4, characterized in that it comprises:

6. the control unit (CU) is equipped with a hydraulic warm-up structure, the control unit (CU) is configured to open the supply valve (FV) and the discharge valve (DV) and to simultaneously maintain the supply valve (FV) and the discharge valve (DV) open to allow a free flow of the hydraulic fluid through at least one working pressure space (11, 12) for the purpose of transferring thermal energy from the hydraulic fluid flow to the impact device (4). A striking device according to any one of claims 1 to 5, characterized in that it comprises:

7. the control unit (CU) is equipped with a shut-off structure, the control unit (CU) is configured to close the supply valve (FV) and the discharge valve (DV) and to simultaneously maintain the supply valve (FV) and the discharge valve (DV) in a closed state to prevent hydraulic fluid from flowing through the at least one controlled working pressure space (11, 12). A striking device according to any one of claims 1 to 6, characterized in that it comprises:

8. the control unit (CU) is configured to detect a rebound magnitude of the piston (9) after a striking action against the tool (6) in response to detection data received from the at least one sensing device (S) for detecting a position of the piston (9); A striking device according to any one of claims 1 to 7, characterized in that it comprises:

9. the control unit (CU) comprises a hydraulic short circuit structure, the control unit (CU) is configured to open the supply valve (FV) and the discharge valve (DV) and to simultaneously keep the supply valve (FV) and the discharge valve (DV) open at or near a turning point of the work cycle (WC) of the piston (9) when the piston movement changes from a return movement (B) to an impact movement (A), A striking device according to any one of claims 1 to 8, characterized in that it comprises:

10. the control unit (CU) comprises a stop structure, the control unit (CU) being configured to close the supply valve (FV) and the discharge valve (DV) and to keep them simultaneously closed at or near the dead center of the work cycle (WC) of the piston (9) when the piston movement changes from the return movement (B) to the impact movement (A), A striking device according to any one of claims 1 to 9, characterized in that it comprises:

11. the control unit (CU) is configured to direct a substantially constant hydraulic fluid pressure into the first working pressure space (11) to move the piston (9) in the return direction (B), and is configured to supply and discharge hydraulic fluid pressure to and from the second working pressure space (12), thereby controlling the reciprocating movement of the piston (9) during the work cycle (WC); A striking device according to any one of claims 1 to 10, characterized in that it comprises:

12. The supply valve (FV) and the discharge valve (DV) are both directly electrically controlled on / off operable valves; A striking device according to any one of claims 1 to 11, characterized in that it comprises:

13. the supply valve (FV) comprises a main supply valve (MFV) controlled by a pressure signal received from a pilot supply valve (PFV); the discharge valve (DV) comprises a main discharge valve (MDV) controlled by a pressure signal received from a pilot discharge valve (PDV); The pilot supply valve (PFV) and the pilot discharge valve (PDV) are independently controlled by the control unit (CU). A striking device according to any one of claims 1 to 11, characterized in that it comprises:

14. A crushing hammer (1) equipped with a hydraulic striking device (4), The striking device (4) is as claimed in any one of claims 1 to 13, A crushing hammer (1) characterized by:

15. A rock drilling machine (41) comprising a hydraulic impact device (4), The striking device (4) is as claimed in any one of claims 1 to 13, A rock-cutting machine (41) characterized in that

16. A method for controlling the operation of a hydraulic impact device (4), comprising: - detecting the position of the piston (9) by at least one sensing device (S) and providing sensory data (SD) collected by said sensing device (S) to at least one control unit (CU); controlling at least one supply valve (FV) and at least one discharge valve (DV) under the control of the control unit (CU) to control the supply and discharge of hydraulic fluid to at least one of the first pressure space (11) and the second pressure space (12) of the striking device (4) to execute a work cycle (WC) of the piston (9) in response to the received sensed data (SD) and control parameters (PA) input to the control unit (CU), wherein the supply valve (FV) and the discharge valve (DV) are controlled to be in an overlap control state where they are both closed or both open during the work cycle (WC); controlling said supply valve (FV) and said discharge valve (DV) independently of each other under the control of said control unit (CU) during said work cycle (WC); Executing at least one overlapping control in a valve control cycle (CC), wherein said supply valve (FV) and said discharge valve (DV) are simultaneously in the same control state; generating in said control unit (CU) a control signal (CS) for controlling said supply valve (FV) and said discharge valve (DV) steplessly and independently of each other according to said overlap control; Including, The method comprises: determining a rebound ratio by comparing a piston impact velocity in an impact direction to a piston rebound velocity in a return direction in response to detected position data received from said at least one sensing device (S); and controlling a state of the overlap control in response to the determined rebound ratio; The method further comprising:

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