EP2855098B1 - Percussion unit - Google Patents

Description

State of the art

There are already Schlagwerkeinheiten, especially for drilling and / or impact hammers, with a control unit which is intended to control a drive unit and / or a pneumatic percussion and / or to regulate known.

A percussion unit according to the preamble of claim 1 is also known from EP 2 189 249 A1 known.

Disclosure of the invention

The invention relates to a percussion unit, in particular for a drill and / or percussion hammer, with a control unit, which is intended to control and / or regulate a drive unit and / or a pneumatic impact mechanism.

It is proposed a pressure sensor unit, which is provided for a measurement of a pressure curve for detecting at least one percussion state. A "percussion unit" is to be understood in this context in particular a unit which is provided for operating the percussion mechanism. The percussion unit may in particular have a control unit. The percussion unit may have a drive unit and / or a gear unit, which is provided for driving the impact mechanism. In this context, a "control unit" is to be understood as meaning, in particular, a device of the impact mechanism unit which is provided for controlling and / or regulating, in particular, the drive unit and / or the percussion mechanism. The control unit may preferably be designed as an electrical, in particular as an electronic control unit. In this context, a "drilling and / or percussion hammer" is intended in particular to mean a machine tool can be understood, which is provided for a machining of a workpiece with a rotating or non-rotating tool, wherein the tool can be acted upon by the machine tool with impact pulses. The machine tool is preferably designed as a hand tool machine guided by a user by hand. In this context, a "percussion mechanism" should be understood as meaning, in particular, a device which has at least one component which is provided for generating and / or transmitting a striking pulse, in particular an axial impact pulse, on a tool arranged in a tool holder. Such a component may in particular be a racket, a firing pin, a guide element, in particular a hammer tube, and / or a piston, such as in particular a pot piston, and / or another component which appears expedient to the person skilled in the art. The racket can transmit the impact pulse directly to the tool or indirectly. Preferably, the racket can transmit the impact pulse to a firing pin, which transmits the impact pulse to the tool. By "intended" is intended to be understood in particular specifically designed and / or specially equipped. The "pressure sensor unit" may in particular include a pressure sensor and a signal processing unit. A "pressure curve" should in particular be understood to mean a time profile of a pressure, in particular of the pressure in a room. In this context, a "striking mechanism condition" is to be understood as meaning, in particular, an operating mode or an operating condition of the percussion mechanism. An "operating mode" is to be understood in this context, in particular, a configuration of the percussion mechanism in which it is intended for a specific operating state, in particular for a percussion mode or an idling mode. An "operating state" is to be understood in this context, in particular a performance of the percussion mechanism, such as in particular the impact mode or the idling mode. The person skilled in the art knows further operating states which determine the operating behavior of the striking mechanism, in particular a striking strength and a striking frequency. In this context, the term "impact mode" is to be understood as meaning, in particular, an operating state of the percussion mechanism in which regular percussion impulses are preferably exerted by the impact mechanism. Preferably, the percussion mechanism is provided in a beat mode to the percussion mode. In this context, "regular" should be understood in particular as recurring, in particular with a designated frequency. Under the "idling mode" should in In this context, in particular, an operating state of the striking mechanism can be understood, which is characterized by the absence of regular impact pulses and / or in which only very weak impact pulses are exerted by the racket on the firing pin. In this context, "very weak" is to be understood in particular as meaning that an impact strength corresponds to less than 50%, preferably less than 25%, particularly preferably less than 10%, of the impact strength in impact mode. Preferably, the hammer mechanism is provided in idle mode to the idle mode. The hammer mechanism may preferably have suitable devices with which it can be switched between the idle mode and the beat mode. Such devices are known in the art. In particular, the percussion mechanism may include a control sleeve which is provided to at least largely release idling orifices in the idling mode and at least substantially close the idling orifices in the striking mode. By "largely" should be understood in this context, at least more than 50%, preferably at least more than 80%. In this context, "idle openings" are to be understood as meaning, in particular, openings, in particular in the hammer tube, which are intended to allow a pressure equalization of a compression space with an adjacent space. In this context, a "compression space" is to be understood as meaning, in particular, a space bounded by the piston and the beater, in particular in the hammer tube. In the impact mode, the piston can accelerate the racket by a piston movement by compressing the volume trapped in the compression space in a direction of impact in the direction of the firing pin. The piston is preferably cyclically moved in the direction of impact and against the direction of impact with a beat frequency and / or a percussion speed. A "percussion speed" is to be understood in this context in particular a speed of an eccentric, which preferably moves the piston via a connecting rod. If the piston executes a movement cycle during one eccentric rotation, the percussion speed corresponds to the beat frequency. The terms are to be understood equivalently below. In the idling mode, the idling openings are at least largely open, so that in the case of changes in volume of the compression space resulting from a change in a distance between the piston and the rack, air can escape through the idling openings and / or flow into the compression space. The piston movement then leads to no or only a slight compression of a volume in Compression space, so that the club is accelerated by the piston movement at most slightly. A "slight acceleration" is to be understood in this context, in particular an acceleration, which leads to an idling operation of the impact mechanism. The percussion state can be advantageously detected by measuring the pressure curve. In particular, the beat mode and / or the beat mode and / or the beat frequency can be advantageously recognized. Other sensors and / or means for detecting the percussion state can be dispensed with. The control unit can respond appropriately to the hammer mechanism condition. Faults and / or deviating operating states and / or operating modes can be detected. The control unit can use the percussion state to control and / or regulation of the impact mechanism and / or the drive unit.

According to the invention, the pressure sensor unit is provided for measuring the pressure variation in a gear compartment, which is in a pressure connection in at least one impact mechanism state with at least one impact area bounded by the piston and / or compression space. In this context, a "striking space" is to be understood as meaning, in particular, a space delimited by the piston and the firing pin and / or a space lying in the direction of impact in front of the piston, in particular in the hammer tube. In this context, a "pressure connection" is to be understood as meaning, in particular, at least one connection which is provided for pressure equalization between two volumes, such as, in particular, an orifice, a channel and / or a pressure line. Preferably, at least in the idle mode, the gear compartment may be in pressure communication with the compression space via the idling orifices in the hammer tube. Preferably, at least in a percussion mode, the gear compartment may be in pressure communication with vents via vent holes in the hammer tube. In this context, "ventilation openings" are to be understood as meaning, in particular, openings, in particular in the hammer tube, which are intended to permit a pressure equalization of the striking space with an adjacent space, in particular a striking mechanism space. In this context, a "percussion space" should be understood as meaning, in particular, a space which at least partially surrounds the hammer tube of the percussion mechanism. The Schlagwerkraum can be at least partially limited by a striking mechanism housing. The striking mechanism housing can be part of the handheld power tool housing and / or a transmission housing. The transmission housing may be part of the hand tool housing. Preferably, the vents can be provided to equalize the pressure of the striking room with the striking mechanism room. Preferably, the idling openings can be provided in the idle mode to a pressure equalization of the compression chamber with the striking mechanism room. The pressure sensor unit can be provided for measuring the pressure profile in the striking mechanism room. The pressure profile in the striking mechanism chamber is influenced, in particular, by the movement of the piston and / or the beater, depending on the operating mode. The pressure curve can be particularly well suited for detecting the percussion state. Depending on the operating mode, the striking mechanism room is in a particularly direct pressure connection with the compression space and the striking space. The course of pressure in the percussion chamber can be particularly characteristic of the striking mechanism condition.

In this context, a "gear chamber" is to be understood as meaning, in particular, a space which preferably adjoins the striking mechanism chamber and in particular surrounds the gear unit of the drive unit. The gear unit may in particular be provided to generate a cyclic movement of the piston from a drive movement of a motor of the drive unit. The gear unit may in particular contain an eccentric gear and / or a connecting rod. The gear chamber has a pressure connection with the striking mechanism chamber, in particular via one or more throttle points. In this context, a "throttle point" should be understood as meaning, in particular, a narrowing of a flow cross section in a transition region between two spaces. The pressure gradient in the gear compartment can be influenced by the pressure curve in the impact mechanism room. The gear compartment is in a pressure connection via the striking mechanism chamber with the compression space and / or the striking space. The pressure curve in the gear compartment may be characteristic of the hammer mechanism condition. The gear chamber and / or the striking space may preferably have at least one striking mechanism ventilation. The impactor ventilation is preferably designed as a pressure equalization valve. The percussion vent is preferably provided for a pressure equalization of the gear housing and / or the impactor room with an environment. In particular, a pressure equalization can take place when a defined differential pressure is exceeded and / or via a throttle point. The throttle point may be provided so that the pressure in the percussion mechanism housing and / or transmission housing on average equalizes an ambient pressure. The control unit may preferably be arranged in or in the vicinity of the gear housing. The signal processing unit of the pressure sensor unit and / or the pressure sensor of the pressure sensor unit can be arranged on a circuit board of the pressure sensor unit. The pressure sensor can be arranged at the measuring location at which the pressure profile is to be measured, or preferably have a pressure connection to the measuring location. The pressure connection may be formed as a channel, tube or preferably as a hose. A measuring hose can lead from the pressure sensor unit to the measuring location. An arrangement of the pressure sensors can be particularly inexpensive. The pressure sensor can be arranged particularly well protected. Contamination of the pressure sensor, in particular with lubricants from the gear housing and / or the striking mechanism space, can be avoided. Preferably, the measuring location and / or the pressure sensor can be arranged in or in the area of the hammer mechanism ventilation. The impactor ventilation can be protected against contamination especially by lubricants. Lubricant protection can protect the pressure sensor and impactor ventilation.

It is further proposed that the control unit is provided to evaluate an amplitude of the pressure profile. An "amplitude" should be understood in this context, in particular a maximum deflection of the pressure curve during a time interval between a minimum and a maximum. The "time interval" preferably corresponds to at least the time interval of a beating cycle and is preferably shorter than 50 beating cycles, particularly preferably shorter than 10 beating cycles. A "beating cycle" is to be understood as meaning a time interval between two beating pulses in impact mode and / or a cyclic piston movement with the beating frequency and / or the beater speed in beating or idling mode. The pressure may in particular by movements of the racket and / or the piston and / or movements of other components, the volume of the percussion chamber and / or gear room and / or further, with the striking mechanism space and / or gear room in connected rooms, fluctuate. The amplitude can in particular be influenced by a total volume of the rooms in pressure communication. The amplitude can be a particularly good measure to detect a percussion state.

It is further proposed that the control unit is provided to evaluate a frequency spectrum of the pressure profile. In this context, a "frequency spectrum" should be understood as meaning, in particular, a frequency spectrum of the pressure curve during the described time interval. Frequencies in the course of pressure can be influenced in particular by movements of the racket and / or the piston and / or be dependent on the beat frequency. In particular, the control unit can evaluate the frequency spectrum by evaluating the amplitude of defined frequencies in the frequency spectrum. The defined frequencies may in particular be the beat frequency determined by the percussion speed and / or multiples thereof. For the evaluation of defined frequencies, the control unit preferably has threshold values with which the amplitudes are compared. The threshold values are preferably adjustable. The frequency spectrum may include features that are particularly suitable for detecting a percussion state.

It is further proposed that the control unit is provided to use the pressure curve for determining the operating mode. The impactor room and / or gear room may be in pressure communication with the whip room in idle mode, with the whip room in impact mode, and the compression room. A total volume of the pressurized rooms may be less in the beat mode than in the idle mode. The amplitude of the pressure curve can be greater in beat mode than in idle mode. The control unit can detect the beat mode if the amplitude is greater than a threshold. The limit value is preferably set so that it falls below in the idle mode and is exceeded in the beat mode. It is further proposed that the control unit is provided to use the pressure curve for determining an operating mode change from the idle mode to the beat mode. The firing pin may preferably be displaceably mounted in the hammer tube. The firing pin may preferably be in communication with the control sleeve. If the tool is pressed against a workpiece, the Tool preferably displace the firing pin against the direction of impact, so that the firing pin shifts the control sleeve against the direction of impact from an idle position to a striking position. In the impact position, the control sleeve can at least largely close the idling opening. The displacement of the firing pin counter to the direction of impact can at least temporarily reduce a distance between the firing pin and the racket and thus the volume of the striking space enclosed in the hammer tube by the racket and firing pin. The total volume of the striking room and percussion room and / or gear room can be at least partially reduced. The pressure curve in the striking mechanism chamber and / or the gear compartment can have a pressure increase at least at times. The control unit can evaluate the pressure increase and recognize a switch from idle mode to the beat mode. The control unit can reliably detect the impact mode and / or the idling mode of the impact mechanism.

It is further proposed that the control unit is provided to use the pressure curve for determining the operating state. In particular, the control unit may be provided to recognize a beat operation from the pressure curve. In particular, the bat can cause a pressure wave in a rebound of the firing pin. The pressure wave can influence the frequency spectrum of the pressure curve. In particular, in the impact mode, the pressure curve can have a frequency component with twice the beat frequency. The control unit can be provided, in particular, to evaluate the frequency component with double beat frequency for impact detection. The impact mode can be detected if the frequency component with double beat frequency is greater than a threshold value assigned to this frequency component for the evaluation. The frequency component can be determined from the measurement of the pressure curve, preferably by a Fourier transformation, particularly preferably by a 1-point Fourier transformation with the double beat frequency. Reliable detection of impact operation may be possible. In particular, the control unit can check in beat mode whether the striking mechanism is in strike mode and / or whether a hammer mechanism start was successful.

It is further proposed that the control unit is provided, in at least one operating state, for a change from idle operation to the impact mode to set the hammer speed to a starting value. Preferably, the starting value can be temporarily set at least until a successful Schlagwerk start. In this context, a "starting value" is to be understood as meaning, in particular, a beating frequency which is suitable for reliably starting the striking mechanism. By "reliable" is to be understood in this context in particular that when switching the percussion from idle mode to the beat mode in more than 90%, preferably in more than 95%, more preferably in more than 99% of cases, the impact mode begins. In particular, a too high percussion speed for a percussion start is unsuitable. From which percussion speed a Schlagwerkstart fails, can depend on the percussion type and in particular an ambient pressure. The percussion speed may be set to an idle value in idle mode. The percussion speed can be set to a work value in beat mode. The labor value may be adjusted depending on a machining mode and / or material to be machined and / or tool type. Idle value and labor value can be identical. The idling value may be increased, in particular in order to achieve better cooling of the striking mechanism by a higher rotational speed of a fan unit driven by the drive unit. If the control unit detects a change of the operating mode from the idle mode to the striking mode and the change from the idling mode to the striking mode remains off, the control unit can lower the striking mechanism speed to the starting value. After the percussion start has been completed, the control unit can set the percussion speed to the work value. A reliability of the impact mechanism can be increased. A performance of the impact mechanism can be increased.

It is further proposed that the control unit is provided to use the pressure curve for determining a maintenance condition. A "maintenance state" is to be understood in this context in particular a state of wear of the impact mechanism. In particular, the control unit may be provided to detect a need for repairs and / or maintenance and cleaning of the striking mechanism. In particular, the control unit may be provided to determine the state of a striking mechanism ventilation. The impactor vent can, when properly operated, prevent a medium pressure in the impactor room and / or gear compartment from rising due to an increase in temperature. The control unit can in particular be provided for this purpose be to evaluate an average of the pressure curve. If the average value increases over a defined period of time and / or exceeds a threshold value, the control unit can output a maintenance signal and alert the user to a malfunction of the striking mechanism ventilation. The person skilled in the art will define further meaningful maintenance conditions on the basis of the pressure curve, which the control unit can signal to the user. A malfunction and / or incipient malfunction can be reliably detected. Maintenance of the impact mechanism can be done on time. Operating failures can be avoided.

It is further proposed that the pressure sensor unit is provided to additionally measure a temperature. A "temperature" should be understood in this context, in particular an ambient temperature at the place of use of the percussion mechanism. In particular, the pressure sensor may include a temperature sensor. The temperature can have an influence on the operation of the impact mechanism. In particular, a viscosity of lubricants and / or a friction of the club motion can be temperature-dependent. Permissible operating values and start values of the hammer mechanism speed can be temperature-dependent. The control unit can set the start value and the work value depending on the temperature. The reliability of the impact operation and / or the striking mechanism start can be increased. The performance of the impact mechanism can be improved. Preferably, the pressure sensor unit uses a temperature sensor for a temperature measurement, which is provided for a temperature-dependent sensor compensation of the pressure sensor. Another temperature sensor can be saved.

It is further proposed that the pressure sensor unit is provided to additionally measure the ambient pressure. In this context, an "ambient pressure" is to be understood as meaning, in particular, an air pressure at a place of use of the percussion mechanism. The air pressure may have an influence on a mean pressure in the racket limited spaces in the hammer tube. In particular, the air pressure may have an influence on the pressure in a space arranged in the direction of impact in front of the racket. In particular, the air pressure can influence the movement of the racket in the return direction. In particular, the movement in the return direction may be unreliable depending on the air pressure at high Schlagwerkdrehzahlen. In particular the permissible starting value of the percussion speed may be dependent on the air pressure. The control unit can set the starting value and the working value as a function of the air pressure. The reliability of the impact operation and / or the striking mechanism start can be increased. The performance of the impact mechanism can be improved.

It is further proposed that the control unit is provided to use the pressure curve for determining the beat frequency. In particular, the control unit can determine the beat frequency from the frequency spectrum of the pressure profile. The frequency spectrum contains a frequency component that corresponds to the beat frequency. The frequency spectrum can contain a further frequency component, which corresponds to twice the beat frequency, especially in the beat mode. The control unit can determine the beat frequency by evaluating maxima of the frequency spectrum in the range of the possible beat frequency and / or in the range of twice the amount of the possible beat frequency. The impact frequency determined from the pressure curve can be used to determine the percussion speed and / or can be used for the control and / or regulation of the drive unit. The beat frequency determined from the pressure curve can be used as a direct control variable to a speed control. On a sensor for determining the percussion speed can be dispensed with. Preferably, the impactor speed determined from the pressure curve can be compared with the speed signal of the drive unit. Malfunctions can be detected.

Further, a hand tool with a percussion unit is proposed with the properties described. The hand tool may have the advantages described.

Furthermore, a method for operating a striking mechanism with the described features is proposed. The method may have the advantages described.

drawing

Further advantages emerge from the following description of the drawing. In the drawing, an embodiment of the invention is shown. The drawing, the description and claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

eine schematische Darstellung eines Bohr- und Schlaghammers mit einer erfindungsgemäßen Schlagwerkeinheit in einem ersten Ausführungsbeispiel in einem Leerlaufmodus,

Fig. 2

eine schematische Darstellung des Bohr- und Schlaghammers in einem Schlagmodus,

Fig. 3

eine schematische Darstellung eines Druckverlaufs in dem Leerlaufmodus in einem Leerlaufbetrieb,

Fig. 4

eine schematische Darstellung des Druckverlaufs in dem Schlagmodus in einem Schlagbetrieb und

Fig. 5

eine schematische Darstellung eines Frequenzspektrums des Druckverlaufs in dem Leerlaufbetrieb und in dem Schlagbetrieb.

Show it:

Fig. 1

a schematic representation of a hammer and percussion hammer with a percussion unit according to the invention in a first embodiment in an idle mode,

Fig. 2

a schematic representation of the hammer and percussion hammer in a strike mode,

Fig. 3

a schematic representation of a pressure curve in the idle mode in an idle mode,

Fig. 4

a schematic representation of the pressure curve in the impact mode in a hitting mode and

Fig. 5

a schematic representation of a frequency spectrum of the pressure curve in the idle mode and in the impact mode.

Description of the embodiment

FIG. 1 shows a drill and percussion hammer 12 with a percussion unit 10. The percussion unit 10 comprises a control unit 14, which is intended to control a drive unit 16 of a pneumatic impact mechanism 18.

The drive unit 16 includes a motor 32 with a gear unit 34 which rotatably drives a hammer tube 38 via a first gear 36 and drives an eccentric 42 via a second gear 40. The hammer tube 38 is rotatably connected to a tool holder 44, in which a tool 46 can be clamped. The tool holder 44 and the tool 46 may be driven for a drilling operation via the hammer tube 38 with a rotating working motion 48. If a racket 24 is accelerated in an impact direction 50 in the direction of the tool holder 44 in an impact operation, it exerts a shock pulse in an impact on a firing pin 52 arranged between the racket 24 and the tool 46, that of the firing pin 52 is passed to the tool 46. The tool 46 exerts a beating working movement 54 by the impact pulse. A piston 56 is also movably mounted in the hammer tube 38 on the side facing away from the impact direction 50 of the racket 24. The piston 56 is periodically moved in the hammer tube 38 in the direction of impact 50 and back again by means of a connecting rod 58 from the eccentric 42 driven by a percussion speed. The piston 56 compresses a pressure pad 62 enclosed in a compression space 60 between the piston 56 and the beater 24 in the hammer tube 38. As the piston 24 moves in the direction of impact 50, the beater 24 is accelerated in the direction of impact 50. An impact operation 94 ( FIG. 4 ) can insert. By a rebound on the firing pin 52 and / or by a by the return movement of the piston 56 against the direction of impact 50 between the piston 56 and the racket 24 resulting negative pressure and / or by a back pressure in a whipping room 64 between the racket 24 and the firing pin 52 the racket 24 are again moved back against the direction of impact 50 and then accelerated again in the direction of impact 50 for a next impact pulse. Whether the movements and in particular the impact mode 94 take place depends on operating parameters, in particular the striking mechanism speed. At too high a percussion speed of the racket 24 can not follow the excited by the piston 56 movement, so that the impact operation 94 is absent. For a Schlagwerkstart the Schlagwerkdrehzahl must then be lowered to a lower starting value.

In a region between racket 24 and firing pin 52 vent openings 66 are arranged in the hammer tube 38, so that the trapped between the racket 24 and the firing pin 52 air can escape. In an area between the racket 24 and the piston 56 idle openings 68 are arranged in the hammer tube 38. The tool holder 44 is mounted displaceably in the direction of impact 50 and is supported on a control sleeve 70. A spring element 72 exerts a force in the direction of impact 50 on the control sleeve 70. In a beat mode ( FIG. 2 ), in which the tool 46 is pressed by the user against a workpiece, the tool holder 44 moves against the force of the spring member 72, the control sleeve 70 so that it covers the idling openings 68. If the tool 46 is set off from the workpiece, the tool holder 44 and the control sleeve 70 by the spring element 72 so in the direction of impact 50 into an idle mode ( FIG. 1 ) shifted, that the control sleeve 70, the idling openings 68 is free. A pressure in the pressure pad 62 between the piston 56 and the racket 24 can escape through the idling openings 68. The racket 24 is in the idle mode not or only slightly accelerated by the pressure pad 62 ( FIG. 1 ). In an idle mode 92, the racket 24 exerts no or only small impact pulses on the firing pin 52. The hammer 12 has a hand tool housing 76 with a handle 78 and an auxiliary handle 80, where it is guided by a user.

A pressure sensor unit 20 is provided for a measurement of a pressure curve 22 for detecting at least one percussion state. The pressure sensor unit 20 is provided for measuring the pressure curve 22 in a gear chamber 124, which is in a pressure connection in at least one striking mechanism state with at least the hammer chamber 64 delimited by the piston 24 and / or the compression chamber 60. The pressure sensor unit 20 comprises a signal processing unit 82 and pressure sensors 84, 86, 88, 126 and 130 arranged on the control unit 14. By measuring with a plurality of pressure sensors 84, 86, 88, 126 and 130, the pressure sensor unit 20 can detect the striking mechanism condition particularly reliably. But it is also possible to realize the invention with only one or only a part of the pressure sensors, which serve to measure the pressure curve in the gear compartment. The skilled person will select the appropriate location and number of pressure sensors 84, 86, 88, 126 and 130.

The pressure sensor 84 is not according to the invention arranged in a hammer room 122. The hammer chamber 122 surrounds the hammer tube 38 and is in pressure communication with the hammer chamber 64 via the vent holes 66. In idle mode, the hammer chamber 122 is in pressure communication with the compression chamber 60 via the idle orifice 68. The hammer 122 is adjacent to the eccentric 42 side the gear chamber 124 at. The gear compartment 124 surrounds the gear unit 34 with the gears 36, 40 and the eccentric 42. The hammer chamber 122 and the gear chamber 124 are located above throttle bodies 134 in pressure connection. The striking mechanism 122 and the gear chamber 124 are located within the power tool housing 76. In the area of the gear chamber 124 a hammer mechanism ventilation 118 is arranged, which is provided for a pressure equalization with an environment of the hammer and percussion hammer 12. The Schlagwerkentlüftung 118 is designed as a pressure relief valve that opens when a specified pressure difference is exceeded. According to the invention, the pressure sensor 86 is arranged in the gear chamber 124 and measures the pressure profile 22 of the gear chamber 124. The pressure sensor 88 is arranged on the side of the overpressure valve of the hammer mechanism ventilation 118 facing the gear chamber 124 and also measures the pressure profile 22 of the gear chamber 124. The pressure sensors 84, 86 and 88 are connected to the signal processing unit 82 via a signal connection 90. Further, the pressure sensors 126 and 130 are arranged on the signal processing unit 82. The pressure sensor 126 is connected to a pressure hose 128 with the striking mechanism 122 not according to the invention. The pressure sensor 130 is not connected to the transmission chamber 124 according to the invention with a pressure hose 132. The pressure sensors 126, 130 are particularly well protected against contamination by grease from the gear chamber 124 or the hammer chamber 122. Since the hammer chamber 122 and the gear chamber 124 are in pressure communication via the throttle bodies 134, the pressure in the hammer chamber 122 and in the gear chamber 124 differs only slightly. In the following, the pressure curve 22 in the gear chamber 124 will be described. Pressure curves in the hammer room 122 are comparable usable for detecting the percussion state and differ only slightly.

The control unit 14 is provided to evaluate an amplitude 26 and a frequency spectrum 28 of the pressure profile 22. The control unit 14 is provided to use the pressure curve 22 for determining an operating mode and an operating state.

FIG. 3 shows a schematic representation of the pressure curve 22 in idle mode in the idle mode 92. The pressure curve 22 has a sinusoidal oscillation, wherein the frequency of the striking mechanism speed of the eccentric 42 and thus corresponds to a movement cycle of the piston 56. The compression space 60, the impact space 64, the impactor space 122 and the gear chamber 124 are in pressure communication. In particular, the movement of the piston 56 with The frequency of the percussion speed causes the pressure curve 22. The racket 24 moves freely and causes in the falling and in the rising edge of the pressure curve 22 in each case in areas 136 and 138 slight deviations from the sinusoidal course. A period T of the pressure curve 22 corresponds to a striking mechanism revolution. The percussion frequency is 1 / T.

FIG. 4 shows a schematic representation of the pressure curve 22 in the impact mode in the impact mode 94. The pressure curve 22 has a sinusoidal oscillation, wherein the frequency of the striking mechanism speed of the eccentric 42 and thus corresponds to a movement cycle of the piston 56. The impact chamber 64, the striking mechanism 122 and the gear chamber 124 are in pressure communication. Thus, the volume of the pressurized rooms is less than in idle mode, since the compression chamber 60 is sealed by the closed by the control sleeve 70 idle opening 68 against the whipping room 64. Due to the smaller volume, the amplitude 26 in the beat mode is greater than in the idle mode ( FIG. 3 ). The racket 24 bounces hard in impact mode 94 of the firing pin 52 back. The rebound causes a significant deviation of the pressure curve 22 of the sinusoidal in the region 140 of its rising edge.

The control unit 14 compares the amplitude 26 with a threshold value 96. In idle mode (FIG. FIG. 3 ), the amplitude 26 is less than the threshold value 96; the control unit 14 detects the idle mode. In beat mode ( FIG. 4 ), the amplitude 26 is greater than the threshold value 96, the control unit 14 detects the beat mode. When changing from idle mode to the beat mode caused by the movement of the firing pin 52 volume change also causes a fluctuation not shown here in the pressure curve 22, which can also use the control unit 14 to detect the change from idle mode to the beat mode.

FIG. 5 shows the frequency spectrum 28 of the pressure curve 22 in idle mode and a frequency spectrum 30 of the pressure curve 22 in the impact mode. In idle mode, the frequency spectrum 28 has a frequency component 98, which corresponds to the beat frequency or percussion speed. In beat mode, the frequency spectrum 30 has an additional frequency component 100, which corresponds to twice the beat frequency. This frequency component 100 is caused by the significant deviation of the pressure curve 22 from the sinusoidal shape in the area 140 due to the rebound of the racket 24 from the firing pin 52 and characterizes the impact mode. The control unit 14 detects the frequency component 100 by means of a Fourier transformation of the pressure curve 22 at twice the beat frequency. If the frequency component 100 exceeds a threshold value 102, the control unit 14 recognizes the impact mode.

The control unit 14 is provided to set the percussion speed to a starting value in at least one striking mechanism state for a change from the idling operation 92 to the striking operation 94. If the control unit 14 detects a change from the idle mode to the striking mode, without a change from the idling mode 92 to the striking mode 94 occurring as a result, the control unit 14 lowers the striking-machine speed to the starting value. The starting value is selected so that a safe hammering start takes place under all conditions. If the control unit 14 detects the impact operation 94, it sets the percussion speed set by the user. The pressure sensor unit 20 is designed to measure an ambient pressure and an ambient temperature. The ambient pressure and the ambient temperature influence the percussion speed, with which a safe percussion start is possible. The control unit 14 sets the starting value depending on ambient pressure and ambient temperature. For this purpose, characteristic maps are stored on the control unit 14 which contain permissible starting values as a function of ambient pressure and ambient temperature.

Further, the control unit 14 is provided to use the pressure curve 22 for determining a maintenance condition. The percussion vent 118 serves to equalize the pressure of the gear chamber 124 with an environment. If the impact mechanism ventilation 118 becomes dirty, the pressure in the transmission chamber 124 increases. The control unit 14 forms an average of the pressure profile 22. If the mean value of the pressure profile 22 rises above a set threshold value for a pressure average, the user is given a signal on a display unit, not shown, that the hammer mechanism ventilation 118 must be serviced.

Further, the control unit 14 is provided to use the pressure curve 22 for determining the beat frequency. The beat frequency corresponds to the frequency of the frequency component 98 of the pressure curve 22 (FIG. FIG. 5 ). The control unit 14 compares the striking mechanism speed determined from the pressure curve 22 with a set setpoint speed and uses this as the feedback variable of a control unit for the drive unit 16 arranged on the control unit 14.

Claims (12)

1. Percussion mechanism unit, in particular for a rotary and/or percussion hammer (12), comprising a control unit (14) that is provided to control a drive unit (16) and/or pneumatic percussion mechanism (18) by open-loop and/or closed-loop control, and comprising a pressure sensor unit (20), which is provided to measure a pressure characteristic (22) for the purpose of identifying at least one percussion mechanism state, characterized in that the pressure sensor unit (20) is provided to measure the pressure characteristic (22) in a transmission space (124) that, in at least one percussion mechanism state, is connected in respect of pressure to at least one percussion space (64) and/or to the compression space (60) delimited by the piston (24).
2. Percussion mechanism unit according to Claim 1, characterized in that the control unit (14) is provided to evaluate an amplitude (26) of the pressure characteristic (22).
3. Percussion mechanism unit as claimed in either one of the preceding claims, characterized in that the control unit (14) is provided to evaluate a frequency spectrum (28, 30) of the pressure characteristic (22).
4. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the control unit (14) is provided to use the pressure characteristic (22) to determine an operating mode.
5. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the control unit (14) is provided to use the pressure characteristic (22) to determine an operating state.
6. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the control unit (14) is provided to set the percussion-mechanism rotational speed to a starting value, in at least one percussion mechanism state, for the purpose of changing from an idling operating state (92) to a percussive operating state (94).
7. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the control unit (14) is provided to use the pressure characteristic (22) to determine a servicing state.
8. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the pressure sensor unit (20) is provided additionally to measure a temperature.
9. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the pressure sensor unit (20) is provided additionally to measure an ambient pressure.
10. Percussion mechanism unit as claimed in any one of the preceding claims, characterized in that the control unit (14) is provided to use the pressure characteristic (22) to determine a percussion frequency.
11. Hand power tool comprising a percussion mechanism unit (10) as claimed in any one of the preceding claims.
12. Method for operating a percussion mechanism unit (10) as claimed in any one of Claims 1 to 10.

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