Electric percussion device and method for controlling the same

Abstract

An electric percussion device comprises a frame (101), an actuator member (103) linearly movable with respect to the frame, and a linear electric machine (104) comprising a mover (105) for directing impacts to the actuator member and a stator (106) having windings for generating a magnetic force directed to the mover when electric currents are supplied to the windings The electric percussion device comprises a power electronic converter (107) for driving the linear electric machine and a controller (108) for controlling the power electronic converter to drive the linear electric machine based on a control signal that defines a temporal behavior of operation of the electric percussion device. For example, impact energy of impacts directed to the actuator member can be ramped up at a beginning phase of a percussion work. This reduces energy consumption and undesired slips of the actuator member from material under the percussion work.

Description

[0001] ELECTRIC PERCUSSION DEVICE AND METHOD FOR CONTROLLING THE SAME

[0002] Field of the disclosure

[0003] The disclosure relates to an electric percussion device, such as an electric hammer device, that is connectable to an excavator or a to working machine of another kind. Furthermore, the disclosure relates to a method for controlling an electric percussion device. Furthermore, the disclosure relates to a computer program for controlling an electric percussion device.

[0004] Background

[0005] Typically, a percussion device is used as an attachment to an excavator or another working machine where the intention is to break up for example stone, concrete, or some other material. The percussion device can be attached e.g. to the boom of an excavator, in place of a bucket. The percussion device incorporates a mechanism configured to direct impacts to an actuator member, e.g. a chisel, whose end forms a tip which transmits the impacts to material to be broken up. At the same time as the impacts are directed to the actuator member, the percussion device is pushed against the material to be broken up. Thus, the above-mentioned tip penetrates, due to the impacts and the pushing, into the material to be broken up, and, consequently, breaks up the material.

[0006] The mechanism to direct impacts to the actuator member is typically hydraulic, but recently also electric mechanisms based on linear electric machines are becoming more common because hydraulic mechanisms have their own challenges. One of the challenges encountered with hydraulic percussion devices is their tendency to cause pressure shocks which can be destructive to the hydraulic system of a working machine. These pressure shocks can be smoothed, but to some extent only, by means of a pressure accumulator. Another challenge of a hydraulic percussion device is that it has a relatively high power consumption. The hydraulic system contains, in the energy flow direction, a plurality of energy-loss producing elements one after another, causing a reduction of the efficiency of the whole system. The energyloss producing elements include, for instance, an engine that drives a hydraulic pump, the hydraulic pump, and a piping and valve system that produces a flow resistance. Heating up of the hydraulic oil in the hydraulic percussion device may also pose its own challenges to the hydraulic system of the working machine.

[0007] On the other hand, an electric percussion device, such as a hammer or a rock drill, is not free from challenges either. One of the challenges is related to a control of a linear electric machine so that unnecessary consumption of energy and / or waste of time can be avoided or at least reduced. For example, a situation in which an actuator member, e.g. a chisel, of an electric percussion device repeatedly slips from a surface of material, e.g. stone or concrete, under a percussion work may cause unnecessary consumption of energy and / or waste of time. Furthermore, situations of the kind mentioned above may damage the electric percussion device. Another exemplifying situation that may cause unnecessary consumption of energy and / or waste of time is a situation in which an actuator member of an electric percussion device has made a pit on a surface of material under a percussion work and there is minced material at the bottom of the pit. The minced material acts as a padding layer that attenuates impacts directed to the solid material.

[0008] Summary

[0009] The following presents a simplified summary to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the invention nor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.

[0010] In this document, the word “geometric” when used as a prefix means a geometric concept that is not necessarily a part of any physical object. The geometric concept can be for example a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other geometric entity that is zero, one, two, or three dimensional. In accordance with the invention, there is provided a new electric percussion device, e.g. an electric hammer device, an electric rock drill device, or an electric impact hammer for piling.

[0011] An electric percussion device according to the invention comprises:

[0012] - a frame attachable to a working machine, the frame comprising attachment members configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,

[0013] - an actuator member, e.g. a chisel, linearly movably supported with respect to the frame,

[0014] - a linear electric machine comprising a mover configured to direct impacts to the actuator member, and a stator attached to the frame and provided with windings configured to generate a magnetic force directed to the mover in response to one or more electric currents supplied to the windings,

[0015] - a power electronic converter configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and

[0016] - a controller configured to control the power electronic converter to drive the linear electric machine.

[0017] The controller is configured to:

[0018] - receive a control signal that defines at least one of following to determine operation of the electric percussion device as a function of time: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and

[0019] - control the power electronic converter to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percussion work.

[0020] The impact energy can be for example ramped up at a beginning phase of a percussion work. This reduces energy consumption and undesired slips of the actuator member from the material, e.g. stone or concrete, under the percussion work. For another example, the temporal behavior of the control signal can be such that first and second operating modes alternate with each other, wherein the impact energy is greater in the first operating mode than in the second operating mode. For example, when breaking stones, strokes with a lower impact energy are less prone to slip from the surface of a stone but these impacts make a pit on the surface so that the risk of slipping with subsequent strokes with a higher impact energy is reduced. On the other hand, the number of successive strokes with the lower impact energy prior to a stroke with the higher impact energy is limited and thus there is no significant risk for a situation where minced material at the bottom of the pit significantly reduces the effect of the stroke with the higher impact energy.

[0021] In accordance with the invention, there is also provided a new method for controlling an electric percussion device that comprises:

[0022] - a frame attachable to a working machine, the frame comprising attachment members configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,

[0023] - an actuator member, e.g. a chisel, linearly movably supported with respect to the frame,

[0024] - a linear electric machine comprising a mover configured to direct impacts to the actuator member, and a stator attached to the frame and provided with windings configured to generate a magnetic force directed to the mover in response to electric current supplied to the windings,

[0025] - a power electronic converter configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and a controller configured to control the power electronic converter to drive the linear electric machine.

[0026] The method according to the invention comprises:

[0027] - receiving a control signal that defines at least one of following to determine operation of the electric percussion device as a function of time: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and

[0028] - controlling the power electronic converter to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percussion work.

[0029] In accordance with the invention, there is also provided a new computer program for controlling an electric percussion device. A computer program according to the invention comprises computer executable instructions for controlling a programmable controller of an electric percussion device to:

[0030] - receive a control signal that defines at least one of following to determine operation of the electric percussion device as a function of time: i) impact energy of impacts directed by a mover of a linear electric machine of the electric percussion device to an actuator member, e.g. a chisel, of the electric percussion device, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and - control a power electronic converter of the electric percussion device to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percussion work.

[0031] In accordance with the invention, there is also provided a new computer program product. The computer program product comprises a non-volatile computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to the invention.

[0032] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0033] Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and nonlimiting embodiments when read in conjunction with the accompanying drawings.

[0034] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require an existence of un-recited features.

[0035] The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0036] Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0037] Brief description of the drawings

[0038] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which: figures 1 a and 1 b illustrate an electric percussion device according to an exemplifying and non-limiting embodiment, figures 1 c, 1 d, 1 e, 1f, 1 g, and 1 h depict exemplifying control signals of the electric percussion device illustrated in figures 1 a and 1 b, and figure 2 shows a flowchart of a method according to an exemplifying and non-limiting embodiment for controlling an electric percussion device.

[0039] Description of exemplifying and non-limiting embodiments

[0040] The invention and the embodiments thereof are not limited to the exemplifying and non-limiting embodiments described below. Thus, the specific examples provided in the description given below should not be construed as limiting the scope and / or the applicability of the appended claims. Lists and groups of examples provided in the description given below are not exhaustive unless otherwise explicitly stated.

[0041] Figure 1a shows an electric percussion device 100 according to an exemplifying and non-limiting embodiment. Figure 1 b shows section view taken along a line A-A shown in Figure 1 a. The geometric section plane is parallel with the yz-plane of a coordinate system 199. The electric percussion device 100 comprises a frame 101 attachable to a working machine, e.g. such as to a boom of an excavator in place of a bucket. The frame 101 comprises attachment members 102 for attaching to the working machine so that the frame 101 is nondestructively detachable from the working machine. The electric percussion device 100 comprises an actuator member 103, e.g. a chisel, linearly movably supported with respect to the frame 101. In this exemplifying case, an end of the actuator member 103 is shaped to constitute a tip for breaking material e.g. stone or concrete. It is also possible that the end of the actuator member is flat or round.

[0042] As illustrated in figure 1 b, the electric percussion device 100 comprises a linear electric machine 104 having a mover 105 and a stator 106. The stator 106 is attached to the frame 101 and is provided with windings configured to generate a magnetic force directed to the mover 105 in response to electric currents supplied to the windings. The mover 105 is configured to direct impacts to the actuator member 103 in the negative z-direction of the coordinate system 199. The windings of the stator 106 may constitute for example a multi-phase winding, e.g. a two- or three- phase winding. In the exemplifying electric percussion device 100 illustrated in figures 1 a and 1 b, the linear electric machine 104 is a tubular linear electric machine in which conductor coils of the windings are configured to surround the mover 105. Figure 1 b shows cross-sectional views of the conductor coils of the windings. In figure 1 b, the cross-sections of the conductor coils are depicted by black rectangular patterns. The mover 105 can be, for example, substantially rotationally symmetric with respect to a geometric line parallel with the z-axis of the coordinate system 199.

[0043] The electric percussion device 100 comprises a power electronic converter 107 configured to drive the linear electric machine 104 by supplying electric currents to the windings of the linear electric machine 104. In the exemplifying case shown in figures 1 a and 1 b, the power electronic converter 107 is an inverter that is connected to a three-phase electric grid via an active rectifier. The electric percussion device 100 comprises a controller 108 configured to control the linear electric machine 104 by controlling controllable power electronic switches of the power electronic converter 107. In this exemplifying case the controllable power electronic switches are insulated gate bipolar transistors “IGBT”, but it is also possible that the controllable power electronic switches are gate-off thyristors “GTO” or some other suitable elements that can be switched on and off.

[0044] The controller 108 is configured to receive a control signal that defines at least one of following to determine operation of the electric percussion device 100 as a function of time: i) impact energy of the impacts directed by the mover 105 to the actuator member 103, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover 105 during an impact stroke of the mover when the mover moves towards the actuator member 103, and iv) average acceleration of the mover 105 during an impact stroke of the mover. Furthermore, the controller 108 is configured to control the power electronic converter 107 to drive the linear electric machine 104 based on the control signal so that the operation of the electric percussion device 100 changes over time in a way determined by the control signal during a percussion work when the actuator member 103 hits material, e.g. stone or concrete, under the percussion work. For example, the impact energy can be ramped up at a beginning phase of the percussion work. This reduces energy consumption and undesired slips of the actuator member 103 from the material, e.g. stone or concrete, under the percussion work. For another example, the temporal behavior of the control signal can be such that first and second operating modes alternate with each other, wherein the impact energy is smaller in the first operating mode than in the second operating mode. An impact frequency can be smaller in the second operating mode than in the first operating mode. For example, when breaking stones, strokes with a lower impact energy are less prone to slip from the surface of a stone but these impacts make a pit on the surface so that the risk of slipping with subsequent strokes with a higher impact energy is reduced. On the other hand, the number of successive strokes with the lower impact energy prior to a stroke with the higher impact energy is limited and thus there is no significant risk for a situation where minced material at the bottom of the pit significantly reduces the effect of the stroke with the higher impact energy. The number of successive strokes with the lower impact energy in the first operation mode can be for example from 2 to 6, whereas the number of successive strokes with the higher impact energy in the second operation mode can be for example from 1 to 4.

[0045] Figures 1 c, 1 d, 1 e, 1f, 1 g, and 1 h depict exemplifying control signals of the electric percussion device 100 illustrated in figures 1 a and 1 b. In the exemplifying case depicted in figure 1c, the control signal has two components 121a and 121 b. The component 121 a defines the impact energy, e.g. in joules, as a function of time and the component 121 b defines the impact frequency, e.g. in impacts per minute, as a function of time. In this exemplifying case, the impact energy and the impact frequency are changed in a stepwise manner. In the exemplifying case depicted in figure 1 d, the control signal has two components 122a and 122b which define the impact energy and the impact frequency, respectively, as continuous functions of time. In the exemplifying case depicted in figure 1 e, the control signal is the following sequence {Ei}, {At2, E2}, {Ats, E3}, ... ., {Atj-1 , EM}, {Atj, Ei}, ... , where E1 is the impact energy of the first impact, Ei is the energy of ithimpact and Atj is a time from the (i - 1 )thimpact to the ithimpact, where i is an integer > 1. In figure 1 e, the impacts are depicted with arrows so that the length of each arrow corresponds to the impact energy of the impact under consideration. In the exemplifying case depicted in figure 1f, the control signal has two components 123a and 123b which define the impact energy and the impact frequency, respectively, as functions of time so that the impact energy is increased while the impact frequency is kept constant. In the exemplifying case depicted in figure 1 g, the control signal has two components 124a and 124b. The component 124a defines a temporal behavior of maximum acceleration amax of the mover 105 during impact strokes of the mover when the mover moves towards the actuator member 103, and the component 124a defines a temporal behavior of the impact frequency. The maximum acceleration amax can be controlled by controlling the magnetic force acting on the mover 105 of the linear electric machine 104. The magnetic force, in turn, is controllable by controlling active current components of the linear electric machine 104. In the exemplifying case depicted in figure 1 h, the control signal has two components 125a and 125b which define a temporal behavior of average acceleration aaveof the mover 105 during impact strokes of the mover and a temporal behavior of the impact frequency, respectively. The average acceleration aavecan be controlled by controlling the magnetic force acting on the mover 105 of the linear electric machine 104.

[0046] In an exemplifying case where the control signal defines the impact energy as a function of time and a desired value of the impact energy is E, e.g. in joules, for a given impact, the controller 108 is configured to control the power electronic converter 107 to drive the linear electric machine 104 so that the speed v of the mover 105 is substantially (2E / m)1 / 2when the mover 105 hits the actuator member 103, where m is the mass of the mover 105. For another example, the impact frequency can be changed by changing temporal durations of phases when the mover 105 moves away from the actuator member 103, e.g. by changing a speed profile of the mover during the phases when the mover 105 moves away from the actuator member 103. Suitable control sequences, which may depend on the position of the mover 105, for the controllable power electronic switches of the power electronic converter 107 can be for example tabulated and stored in a memory for achieving desired operation. The invention is however not limited to any specific ways to control the power electronic converter 107 to drive the linear electric machine 104 so that operation of the electric percussion device 100 follows requirements defined by the control signal. In an electric percussion device according to an exemplifying and non-limiting embodiment, the control signal defines the impact energy and the impact frequency. Thus, the control signal has at least two components, one defining the impact energy and the other one defining the impact frequency. In this exemplifying embodiment, the controller 108 is configured to control the power electronic converter 107 to drive the linear electric machine 104 based on the control signal so that the impact energy and the impact frequency change over time in a way determined by the control signal during the percussion work.

[0047] In an electric percussion device according to an exemplifying and non-limiting embodiment, a user interface 109 of the electronic percussion device comprises one or more adjusters for generating the control signal so that the control signal is changeable by a user of the electric percussion device during the percussion work. Thus, in this exemplifying embodiment, the controller 108 is configured to receive the control signal from the user interface 109. In figure 2b, the control signal received from the user interface 109 is depicted with an arrow 120a. In the exemplifying electric percussion device illustrated in figures 1a and 1 b, the user interface 109 comprises an adjuster 112 for controlling the impact energy ‘E’ and an adjuster 113 for controlling the impact frequency ‘f’. Each adjuster may comprise for example a stepless regulator enabling the user to change the control signal, or a respective component of the control signal, in a stepless manner. It is also possible that each adjuster comprises + and - buttons for increasing and decreasing the control signal, or a respective component of the control signal, in a stepwise manner.

[0048] An electric percussion device according to an exemplifying and non-limiting embodiment comprises a memory 110 that stores one or more control profiles each defining a control profile-specific behavior of the control signal as a function of time. Thus, in this exemplifying embodiment, the controller 108 is configured to receive the control signal from the memory 110. In figure 2b, the control signal received from the memory 110 is depicted with an arrow 120b. For example, the controller 108 can be configured to retrieve, from the memory 110, one of the control profiles in response to receiving, from the user interface 109, pointer data identifying the one of the control profiles from among the other control profiles. Thus, the user, i.e. the operator, of the percussion device can select a suitable control profile from among pre-defined control profiles stored in the memory 110. One of the pre-defined control profiles can be for example such that the impact energy increases along time from a beginning of the percussion work until a predetermined impact energy has been reached, e.g. to implement soft start operation. Another one of the pre-defined control profiles can be for example such that first and second operating modes alternate with each other, and the impact energy is smaller in the first operating mode than in the second operating mode. The impact frequency can be smaller in the second operating mode than in the first operating mode.

[0049] In the exemplifying electric percussion device illustrated in figures 1a and 1 b, the controller 108 and the memory 110 are elements of the power electronic converter 107 so that the controller 108 and the memory 110 are located inside a casing of the power electronic converter 107. The user interface 109 of the percussion device is communicatively connected via a data transfer link 111 to the controller 108. The data transfer link 111 may comprise e.g. a wired link, a fiber link, or a short-range radio link such as a Bluetooth® link. As mentioned above, the memory 110 can be arranged to store pre-defined control profiles and a suitable one of the control profiles can be selected by submitting pointer data to the controller 108 via the data transfer link 111. Furthermore, the memory 110 can be arranged to store sets of operating parameters defining different operation modes of the electric percussion device. A desired one of the operation modes can be selected by submitting a selector pointer to the controller 108 via the data transfer link 111. Thus, there is no need to transfer all the data defining the selected operating mode via the data transfer link 111 but it suffices to transfer the selector pointer only. Thus, the change between operating modes can be faster and capacity of the data transfer link 111 can be saved. The selector pointer and the corresponding operating mode may relate for example to material under percussion work, a user i.e. an operator of the electric percussion device, and / or one or more environmental conditions, e.g. temperature and / or a rain vs. dry weather, of an operating environment of the electric percussion device.

[0050] In an electric percussion device according to an exemplifying and non-limiting embodiment, the memory 110 is configured to store one or more control profiles each defining a control profile-specific behavior of the control signal 120b as a function of time, and the controller 108 is configured to receive the control signal 120b from the memory. The one or more control profiles comprises at least one of following: i) a control profile such that the impact energy of the impacts increases along time from a beginning of the percussion work until a predetermined impact energy has been reached, and ii) a control profile such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

[0051] The implementation of the controller 108 shown in figures 1a and 1 b can be based on one or more analogue circuits, one or more digital processing circuits, or a combination thereof. Each digital processing circuit can be a programmable processor circuit provided with appropriate software, a dedicated hardware processor such as for example an application specific integrated circuit “ASIC”, or a configurable hardware processor such as for example a field programmable gate array “FPGA”. Furthermore, the controller 108 may comprise one or more memory elements each of which can be for example a Random-Access Memory “RAM” element. The memory 110 shown in figures 1a and 1 b can be for example a solid-state drive “SSD” memory.

[0052] It is to be noted that electric percussion devices according to embodiments of the invention are not limited to any specific type or types of linear electric machines. For example, the linear electric machine of an electric percussion device according to an exemplifying and non-limiting embodiment can be a permanent magnet synchronous machine that comprises permanent magnets in a mover, a flux switching permanent magnet synchronous machine ’’FSPMSM” where permanent magnets are located in a stator, a reluctance linear electric machine, or a linear induction machine. In a reluctance linear electric machine, all magnetic flux is produced by electric currents and a magnetic force directed to the mover is generated by reluctance variation based on the mechanical design of the mover. Correspondingly, in a linear induction machine, all magnetic flux is produced by electric currents and a magnetic force directed to the mover is generated by currents induced in the mover. Thus, no permanent magnets are needed is a reluctance linear electric machine nor in a linear induction machine. Figure 2 shows a flowchart of a method according to an exemplifying and non-limiting embodiment for controlling an electric percussion device that comprises:

[0053] - a frame attachable to a working machine, the frame comprising attachment members configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,

[0054] - an actuator member linearly movably supported with respect to the frame,

[0055] - a linear electric machine comprising a mover configured to direct impacts to the actuator member, and a stator attached to the frame and provided with windings configured to generate a magnetic force directed to the mover in response to one or more electric currents supplied to the windings,

[0056] - a power electronic converter configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and

[0057] - a controller configured to control the power electronic converter to drive the linear electric machine.

[0058] The method comprises the following actions:

[0059] - action 201 : receiving a control signal that defines at least one of following to determine operation of the electric percussion device as a function of time: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during an impact stroke of the mover, and

[0060] - action 202: controlling the power electronic converter to drive the linear electric machine based the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during percussion work when the actuator member hits material under the percussion work. In a method according to an exemplifying and non-limiting embodiment, the control signal defines the impact energy and the impact, and the method comprises controlling the power electronic converter to drive the linear electric machine based on the control signal so that the impact energy and the impact frequency change over time in a way determined by the control signal during the percussion work.

[0061] A method according to an exemplifying and non-limiting embodiment comprises generating the control signal with one or more adjusters of a user interface of the electronic percussion device so that the control signal is changed by a user of the electric percussion device during the percussion work. Each adjuster may comprise for example a stepless regulator enabling the user to change the control signal, or a respective component of the control signal, in a stepless manner.

[0062] A method according to an exemplifying and non-limiting embodiment comprises receiving the control signal from a memory configured to store one or more control profiles each defining a control profile-specific behavior of the control signal as a function of time. A desired one of the control profiles can be retrieved from the memory for example in response to receiving, from the user interface of the electronic percussion device, pointer data identifying the one of the control profiles from among the other control profiles. One of the control profiles can be for example such that the impact energy increases along time from a beginning of the percussion work until a predetermined impact energy has been reached. Another one of the control profiles can be for example such that first and second operating modes alternate with each other, and the impact energy is smaller in the first operating mode than in the second operating mode.

[0063] In a method according to an exemplifying and non-limiting embodiment, the above- mentioned memory is a part of the power electronic converter so that the memory is located inside a casing of the power electronic converter, and the method comprises transferring the above-mentioned pointer data from the user interface of the percussion device to the power electronic converter via a data transfer link.

[0064] A method according to an exemplifying and non-limiting embodiment comprises receiving the control signal from a memory configured to store one or more control profiles each defining a control profile-specific behavior of the control signal as a function of time. The one or more control profiles comprises at least one of following: i) a control profile such that the impact energy of the impacts increases along time from a beginning of the percussion work until a predetermined impact energy has been reached, and ii) a control profile such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

[0065] A computer program according to an exemplifying and non-limiting embodiment comprises computer executable instructions for controlling a programmable controller of an electric percussion device to carry out actions related to a method according to any of the above-described exemplifying and non-limiting embodiments.

[0066] A computer program according to an exemplifying and non-limiting embodiment comprises software modules for controlling an electric percussion device. The software modules comprise computer executable instructions for controlling a programmable controller of the electric percussion device to:

[0067] - receive a control signal that defines at least one of following to determine operation of the electric percussion device as a function of time: i) impact energy of impacts directed by a mover of a linear electric machine of the electric percussion device to an actuator member, e.g. a chisel, of the electric percussion device, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during an impact stroke of the mover, and

[0068] - control a power electronic converter of the electric percussion device to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percussion work.

[0069] The software modules can be for example subroutines or functions implemented with programming tools suitable for the programmable controller. A computer program product according to an exemplifying and non-limiting embodiment comprises a computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to an exemplifying embodiment of invention.

[0070] A non-volatile computer readable medium according to an exemplifying and non- limiting embodiment is encoded with a computer program according to an exemplifying embodiment of invention.

[0071] A signal according to an exemplifying and non-limiting embodiment is encoded to carry information defining a computer program according to an exemplifying embodiment of invention. The invention and the embodiments thereof are not limited to the exemplifying and non-limiting embodiments described above. Thus, the specific examples provided in the description given above should not be construed as limiting the scope and / or the applicability of the appended claims. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:1 . An electric percussion device (100) comprising:- a frame (101 ) attachable to a working machine, the frame comprising attachment members (102) configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,- an actuator member (103) linearly movably supported with respect to the frame (102),- a linear electric machine (104) comprising a mover (105) configured to direct impacts to the actuator member (103), and a stator (106) attached to the frame (102) and provided with windings configured to generate a magnetic force directed to the mover (105) in response to one or more electric currents supplied to the windings,- a power electronic converter (107) configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and- a controller (108) configured to control the power electronic converter to drive the linear electric machine, characterized in that the controller is configured to:- receive a control signal (120a, 120b) that defines at least one of following to determine operation of the electric percussion device: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and- control the power electronic converter to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during apercussion work when the actuator member hits material under the percussion work.

2. An electric percussion device according to claim 1 , wherein the control signal defines the impact energy and the impact frequency, and the controller (108) is configured to control the power electronic converter to drive the linear electric machine based on the control signal so that the impact energy and the impact frequency change over time in a way determined by the control signal during the percussion work.

3. An electric percussion device according to claim 1 or 2, wherein a user interface (109) of the electronic percussion device comprises one or more adjusters (112, 113) for generating the control signal (120a) so that the control signal is changeable by a user of the electric percussion device during the percussion work, and the controller (108) is configured to receive the control signal from the user interface.

4. An electric percussion device according to claim 3, wherein each adjuster (112, 113) comprises a stepless regulator enabling the user to change the control signal in a stepless manner.

5. An electric percussion device according to any one of claims 1 -4, wherein the electronic percussion device comprises a memory (110) storing one or more control profiles each defining a control profile-specific behavior of the control signal (120b) as a function of time, and the controller (108) is configured to receive the control signal (120b) from the memory.

6. An electric percussion device according to claim 5, wherein the controller (108) is configured to retrieve, from the memory (110), one of the control profiles in response to receiving, from a user interface (109) of the electronic percussion device, pointer data identifying the one of the control profiles from among the other control profiles.

7. An electric percussion device according to claim 5 or 6, wherein one of the one or more control profiles is such that the impact energy of the impacts increasesalong time from a beginning of the percussion work until a predetermined impact energy has been reached.

8. An electric percussion device according to any one of claims 5-7, wherein one of the one or more control profiles is such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

9. An electric percussion device according to any one of claims 5-8, wherein the controller (108) and the memory (110) are located inside a casing of the power electronic converter (107), and a user interface (109) of the electric percussion device is communicatively connected via a data transfer link (111 ) to the controller (108).

10. An electric percussion device according to claim 1 , wherein the electric percussion device comprises a memory (110) storing one or more control profiles each defining a control profile-specific behavior of the control signal (120b) as a function of time, and the controller (108) is configured to receive the control signal (120b) from the memory, the one or more control profiles comprising at least one of following: i) a control profile such that the impact energy of the impacts increases along time from a beginning of the percussion work until a predetermined impact energy has been reached, and ii) a control profile such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

11. A method for controlling an electric percussion device (100) that comprises:- a frame (101 ) attachable to a working machine, the frame comprising attachment members (102) configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,- an actuator member (103) linearly movably supported with respect to the frame (102),- a linear electric machine (104) comprising a mover (105) configured to direct impacts to the actuator member (103), and a stator (106) attached to the frame (102) and provided with windings configured to generate a magneticforce directed to the mover (105) in response to one or more electric currents supplied to the windings,- a power electronic converter (107) configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and- a controller (108) configured to control the power electronic converter to drive the linear electric machine, characterized in that the method comprises:- receiving (201 ) a control signal (120a, 120b) that defines at least one of following to determine operation of the electric percussion device: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and- controlling (202) the power electronic converter to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percussion work.

12. A method according to claim 11 , wherein the control signal defines the impact energy and the impact frequency, and the method comprises controlling the power electronic converter to drive the linear electric machine based on the control signal so that the impact energy and the impact frequency change over time in a way determined by the control signal during the percussion work.

13. A method according to claim 11 or 12, wherein the method comprises generating the control signal (120a) with one or more adjusters (112, 113) of a user interface (109) of the electronic percussion device so that the control signal is changed by a user of the electric percussion device during the percussion work.

14. A method according to claim 13, wherein each adjuster (112, 113) comprises a stepless regulator enabling the user to vary the control signal in a stepless manner.

15. A method according to any one of claims 11 -14, wherein the method comprises receiving the control signal (120b) from a memory (110) configured to store one or more control profiles each defining a control profile-specific behavior of the control signal (120b) as a function of time.

16. A method according to claim 15, wherein the method comprises retrieving, from the memory, one of the control profiles in response to receiving, from a user interface of the electronic percussion device, pointer data identifying the one of the control profiles from among the other control profiles.

17. A method according to claim 16, wherein the memory (110) is located inside a casing of the power electronic converter (107), and the method comprises transferring the pointer data from a user interface (109) of the percussion device to the power electronic converter (107) via a data transfer link (111 ).

18. A method according to any one of claims 15-17, wherein a first one of the control profiles is such that the impact energy of the impacts increases along time from a beginning of the percussion work until a predetermined impact energy has been reached.

19. A method according to any one of claims 15-18, wherein a second one of the control profiles is such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

20. A method according to claim 11 , wherein the method comprises receiving the control signal (120b) from a memory (110) storing one or more control profiles each defining a control profile-specific behavior of the control signal (120b) as a function of time, the one or more control profiles comprising at least one of following: i) a control profile such that the impact energy of the impacts increases along time from a beginning of the percussion work until a predetermined impact energy has beenreached, and ii) a control profile such that first and second operating modes alternate with each other, the impact energy being smaller in the first operating mode than in the second operating mode.

21. A computer program for controlling an electric percussion device (100) that comprises:- a frame (101 ) attachable to a working machine, the frame comprising attachment members (102) configured to attach to the working machine so that the frame is nondestructively detachable from the working machine,- an actuator member (103) linearly movably supported with respect to the frame (102),- a linear electric machine (104) comprising a mover (105) configured to direct impacts to the actuator member (103), and a stator (106) attached to the frame (102) and provided with windings configured to generate a magnetic force directed to the mover (105) in response to one or more electric currents supplied to the windings,- a power electronic converter (107) configured to drive the linear electric machine by supplying the one or more electric currents to the windings, and- a programmable controller (108) configured to control the power electronic converter to drive the linear electric machine, characterized in that the computer program comprises computer executable instructions for controlling the programmable controller to:- receive a control signal (120a, 120b) that defines at least one of following to determine operation of the electric percussion device: i) impact energy of the impacts directed by the mover to the actuator member, ii) an impact frequency being a frequency of the impacts directed by the mover to the actuator member, iii) maximum acceleration of the mover during an impact stroke of the mover when the mover moves towards the actuator member, and iv) average acceleration of the mover during the impact stroke of the mover, and- control the power electronic converter to drive the linear electric machine based on the control signal so that the operation of the electric percussion device changes over time in a way determined by the control signal during a percussion work when the actuator member hits material under the percus- sion work.

22. A non-volatile computer readable medium encoded with a computer program according to claim 21 .

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