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EP-4739463-A1 - AN ELECTRIC PERCUSSION DEVICE AND A METHOD FOR CONTROLLING THE SAME

EP4739463A1EP 4739463 A1EP4739463 A1EP 4739463A1EP-4739463-A1

Abstract

An electric percussion device (100) 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 sensor system (107) for detecting situations where the mover passes a control limit position with respect to the frame. The electric percussion device comprises a controller (108) configured to control the linear electric machine to decrease the magnetic force directed to the mover in response to a situation in which a predetermined time has elapsed after the mover has passed the control limit position when moving towards the actuator member. Thus unwanted current peaks can be avoided when the mover hits the actuator member.

Inventors

  • PELTOLA, Jyri
  • PELTOLA, TUOMO

Assignees

  • Lekatech Oy

Dates

Publication Date
20260513
Application Date
20240617

Claims (15)

  1. 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 electric current supplied to the windings, and - a sensor system (107) configured to detect situations in which the mover passes a control limit position with respect to the frame, characterized in that the electric percussion device comprises a controller (108) configured to control the linear electric machine to decrease the magnetic force directed to the mover (105) of the linear electric machine (104) in response to a situation in which a first predetermined time has elapsed after the mover (105) has passed the control limit position when moving in a first direction (-z) towards the actuator member (103).
  2. 2. An electric percussion device according to claim 1 , wherein the controller (108) is configured to activate the linear electric machine (104) to generate a magnetic force tending to move the mover (105) in a second direction (+z) away from the actuator member in response to a situation in which the mover (105) moves in the second direction and the mover (105) passes the control limit position.
  3. 3. An electric percussion device according to claim 1 or 2, wherein the controller (108) is configured to deactivate the linear electric machine (104) in order to de- crease the magnetic force in response to the situation in which the first predetermined time has elapsed after the mover (105) has passed the control limit position when moving in the first direction (-z) towards the actuator member (103).
  4. 4. An electric percussion device according to claim 3, wherein the controller (108) is configured to set controllable power electronic switches of a supply inverter of the linear electric machine into a unidirectionally conductive state in order to deactivate the linear electric machine.
  5. 5. An electric percussion device according to any one of claims 1 -4, wherein the controller is configured to activate the linear electric machine to generate the magnetic force tending to move the mover in the second direction (+z) away from the actuator member in response to a situation in which a second predetermined time has elapsed after the mover passed the control limit position when moving in the first direction, the second predetermined time being longer than the first predetermined time.
  6. 6. An electric percussion device according to any one of claims 1 -5, wherein the sensor system (107) comprises a first inductive sensor (111 ) configured to detect the situation in which the mover passes the control limit position.
  7. 7. An electric percussion device according to any one of claims 1 -6, wherein the sensor system (107) is configured to detect situations in which the mover passes a safety limit position being farther in the first direction than the control limit position, and the controller is configured to prevent activation of the linear electric machine in response to a situation in which the mover has passed the safety limit position when moving in the first direction.
  8. 8. An electric percussion device according to claim 7, wherein the sensor system comprises a second inductive sensor (112) configured to detect the situation in which the mover passes the safety limit position.
  9. 9. An electric percussion device according to any one of claims 1 -8, wherein the linear electric machine (104) is a tubular linear electric machine in which conductor coils (119, 120) of the windings are configured to surround the mover (105).
  10. 10. 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, - a linear electric machine (104) comprising a mover (105) configured to direct impacts to the actuator member and a stator (106) 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, and - a sensor system (107) configured to detect situations in which the mover passes a control limit position with respect to the frame, characterized in that the method comprises controlling (201 ) the linear electric machine to decrease the magnetic force directed to the mover in response to a situation in which a first predetermined time has elapsed after the mover has passed the control limit position when moving in a first direction (-z) towards the actuator member.
  11. 11. A method according to claim 10, wherein the method comprises activating the linear electric machine to generate a magnetic force tending to move the mover in a second direction (+z) away from the actuator member in response to a situation in which the mover moves in the second direction and the mover passes the control limit position.
  12. 12. A method according to claim 10 or 11 , wherein the method comprises deactivating the linear electric machine in order to decrease the magnetic force in response to the situation in which the first predetermined time has elapsed after the mover has passed the control limit position when moving in the first direction (-z) towards the actuator member.
  13. 13. A method according to claim 12, wherein the method comprises setting controllable power electronic switches of a supply inverter of the linear electric machine into a unidirectionally conductive state in order to deactivate the linear electric machine.
  14. 14. A method according to any one of claims 10-13, wherein the method comprises activating the linear electric machine to generate the force tending to move the mover in the second direction (+z) away from the actuator member in response to a situation in which a second predetermined time has elapsed after the mover passed the control limit position when moving in the first direction, the second predeter- mined time being longer than the first predetermined time.
  15. 15. A method according to any one of claims 10-14, wherein the sensor system is configured to detect situations in which the mover passes a safety limit position being farther in the first direction than the control limit position, and the method comprises preventing activation of the linear electric machine in response to a situation in which the mover has passed the safety limit position when moving in the first direction.

Description

An electric percussion device and a method for controlling the same Field of the disclosure The disclosure relates to an electric percussion device, such as an electric hammer device, with a linear electric machine, 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. Background 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. 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. 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. For example, back-and-forth oscillations of a mover of a linear electric machine which may occur after the mover has directed an impact to the actuator member, e.g. a chisel, typically increase a time needed between successive impacts directed to the actuator member and thereby reduce a stroke frequency of the electric percussion device. The stroke frequency, in turn, is proportional to the efficiency of the electric percussion device to e.g. break up material. Furthermore, control methods which are commonly used in conjunction with hydraulic percussion devices are not, as such, applicable in conjunction with electric percussion devices. Summary 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 of the invention. 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. An electric percussion device according to the invention comprises: a frame attachable to a working machine such as an excavator, the frame comprising attachment members configured to attach to the working machine so that the frame is nondestructively detachable from the working machine, - an actuator member, e.g. a chisel, linearly movably supported with respect to the frame, - 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, - a sensor system configured to detect situations in which the mover passes a control limit position with respect to the fr