EP2855094A1

EP2855094A1 - Percussion unit

Info

Publication number: EP2855094A1
Application number: EP13720306.3A
Authority: EP
Inventors: Rainer Nitsche; Antoine Vandamme; Thomas Winkler; Helge SPRENGER; Haris Hamedovic; Wolfgang Fischer; Christian Bertsch; Mario Eduardo VEGA ZAVALA; Ulli Hoffmann; Thilo Henke; Achim Duesselberg
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2012-05-25
Filing date: 2013-04-24
Publication date: 2015-04-08
Also published as: JP2015517410A; CN104334316A; WO2013174594A1; US10350742B2; DE102012208902A1; US20150101835A1; JP5931282B2

Abstract

Percussion unit, especially for a rotary hammer and/or percussion hammer (12a; 12c; 12d), comprising a control unit (14a; 14c; 14d) which is designed for controlling a pneumatic percussion mechanism (16a; 16c; 16d). According to the invention, the control unit (14a; 14c; 14d) comprises at least one load estimation device (18a; 18c; 18d),

Description

description

Percussion unit

State of the art

There are already Schlagwerkinheiten, especially for a drill and / or percussion hammer, with a control unit, which is intended to control a pneumatic percussion known.

DISCLOSURE OF THE INVENTION The invention is based on a percussion unit, in particular for one

Drilling and / or percussion hammer, with a control unit intended to control a pneumatic impact mechanism.

It is proposed that the control unit has at least one load estimator. In this context, a "percussion unit" should be understood as meaning, in particular, a unit which is provided for operating a percussion mechanism The percussion unit may, in particular, comprise a control unit The percussion unit may comprise a drive unit and / or a gear unit which provides for driving the percussion unit Under a "control unit" is in this context, in particular a

Device of percussion unit to be understood, which is provided for a control and / or regulation, in particular of the drive unit and / or percussion unit. The drive unit may be provided in particular for driving the striking mechanism. The drive unit can be further provided to drive a tool with a rotating working movement. The Drive unit may in particular contain a motor and a gear unit to a translation of the drive movement. The control unit may preferably be designed as an electrical, in particular as an electronic control unit. In this context, a "hammer drill and / or percussion hammer" should be understood as meaning, in particular, a machine tool which is provided for machining a workpiece with a rotating or non-rotating tool, the tool being able to be acted upon by the machine tool with impact pulses. A "percussion mechanism" is to be understood in this context, in particular, as a device which has at least one component which results in the generation and / or transmission of a percussion pulse, in particular an axial percussion impulse , is provided on the arranged in a tool holder tool. Such a component may in particular be a racket, a striking bolt, a guide element, such as in particular a hammer tube and / or a

Pistons, such as in particular a pot piston, and / or another, the skilled person appear reasonable sense component. 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. A "load estimator" is to be understood in this context to mean, in particular, a device and / or an algorithm which is or are intended to have a value taking into account at least one input value and / or estimate the course of at least one unknown parameter. The load estimator preferably takes into account at least one known parameter. In this context, "parameters" are to be understood as influencing variables in particular Parameters may have defined values, in particular parameters may be functions of the time and / or rotational position and / or other variables Load estimators are known to the person skilled in the art from control engineering In this context, the term "estimate" is to be understood in particular to mean that an absolute value and / or value profile of the estimated parameter corresponds sufficiently well to an actual parameter that it is used as a representation for a given task the actual parameter is sufficient. A person skilled in the art will determine a required accuracy of an estimate depending on the task. Preferably, the estimation of a parameter may sufficiently well correspond to an actual value if it deviates by less than 50%, preferably by less than 25%, from the actual value. The control unit can evaluate the estimated parameter. A measurement of the actual parameter can be omitted. The control unit can take into account parameters that can only be measured with great effort. The control unit can take into account parameters that are only unreliable to measure.

It is further proposed that the load estimator is designed as a load observer. In this context, a "load observer" should be understood to mean, in particular, a load estimator which estimates at least one parameter of a physical system from at least one input value by means of a system model A "system mode" is to be understood in this context in particular as a simplified mathematical simulation of a physical system be understood. The system model contains in particular a dynamic model of the physical system. A dynamic model at least partially accounts for the effects of dynamic mass forces of the physical system. The system model represents, in particular, a simplified simulation of the physical system permissible for the application, if an absolute value and / or value profile of the estimated parameter corresponds sufficiently well to an actual parameter of the physical system that it represents the actual parameter for a given task enough. In this context, a "physical system" is to be understood as meaning, in particular, one or more components of the percussion unit, in particular a drive unit The control unit can evaluate the estimated parameter The parameter can be estimated particularly accurately with a load observer at least partially take into account dynamic forces.

It is further proposed that the control unit is provided to detect an operating state of the impact mechanism. Preferably, the control unit is provided for a percussion operation and / or an idling operation of Recognize and / or distinguish percussion. However, the control unit can also be provided to detect other operating states of the percussion mechanism, in particular a beat frequency, an impact strength or other operating states which appear to be appropriate to the person skilled in the art. In this context, a "hammering operation" is to be understood as meaning, in particular, an operating state of the percussion mechanism in which the percussion mechanism preferably applies regular impact impulses. In this context, an "idling operation" is to be understood as meaning, in particular, an operating condition of the percussion mechanism due to the absence of regular percussion impulses is marked. In particular, the control unit can monitor the operating state of the

Determine the impact mechanism taking into account the parameter estimated by the load estimator. The operating condition of the striking mechanism can be advantageously recognized. The control unit can set operating parameters of the impact mechanism so that a desired operating state is ensured.

It is proposed that the control unit is provided to process at least one operating parameter. The operating parameter can in particular form an input value of the load estimator. The operating parameter is preferably formed by an operating parameter of a drive control. In this context, a "drive control" is to be understood as meaning, in particular, a control unit which is provided for speed control of the drive unit of the percussion mechanism unit Drive unit is used. The operating parameter may preferably be a current consumption of the drive unit and / or particularly preferably a rotational speed of the motor of the drive unit. If a speed is detected on a transmission, the speed of the motor can be calculated from this speed at a known ratio. The control unit can use existing operating parameters. A measurement and / or determination of further operating parameters can be omitted.

It is further proposed that the control unit be provided to process the operating parameter as a function of at least one known load and at least one load to be estimated. The estimated load can be dere be a small and / or fast, highly dynamic load change of the drive unit. In this context, a "load" should in particular be understood to mean a load moment which acts on a drive shaft of the drive unit, In particular, the load to be estimated may be caused at least in part by the impact operation, in particular by a cyclic one

Movement of a piston of the striking mechanism. In this context, a "small load change" is to be understood as meaning, in particular, a load change which causes a speed fluctuation of less than 10%, preferably less than 5%, during uncontrolled operation of the drive unit in this

Associated in particular a load change are understood, which occurs within a movement cycle of the piston, in particular during a revolution of the piston driving eccentric gear. If known loads are taken into account, the load to be estimated can be determined with better accuracy. In particular, with the aid of the operating parameter, a small and / or highly dynamic load can be estimated, which is covered by known loads when the operating parameter is viewed directly. In this context, "covered" is to be understood in particular as meaning that the unknown parameter has a small share in the course of the operating parameter, in particular less than 50%, preferably less than 30%, particularly preferably less than 10% of an amplitude of the operating parameter A load torque acting on the drive unit by a machining operation with a rotating working movement with a drilling tool causes a greater change in a rotational speed or current consumption than the impact mode of the percussion mechanism The control unit is preferably designed to process a rotational speed of the drive unit as an operating parameter, the rotational speed can be detected particularly dynamically, other sensors can be dispensed with unit intended to take account of known loads with known period duration. The control unit may be designed to take account of time-periodic loads. Time-periodic loads may in particular be dependent on a frequency of a power supply of the drive unit. For example, a fluctuation in the power supply of the drive unit of the double Mains frequency correspond to the power grid to which the percussion unit is connected. The control unit may be designed to take into account angular periodic loads. Angular periodic loads may be dependent in particular on a rotational position of the drive unit. An angular periodic load may be dependent, in particular, on a variable transmission of an eccentric drive that is variable with the rotational position of the drive unit. The load estimator preferably determines an estimate of the course of the unknown load over time by subtracting the known variables from a profile of the operating parameter over time, in particular a measured speed curve of the motor of the drive unit. The known loads may be functions as a function of time and / or of the rotational position of the drive unit. A known load may be a base and / or desired speed of the drive unit. This speed changes only slowly and can be determined by averaging over time and / or by a low-pass filter. Other known loads may include, for example, speed variations due to motor nonuniformity, non-uniform voltage supply to the motor, and variable gear ratios. These loads can be time and / or angle dependent according to their dependency. Functions of these loads can be determined by a person skilled in the art. The unknown load can be estimated very accurately. The estimated load may be particularly suitable

Recognize operating status. The unknown load may preferably be a speed fluctuation caused by the impact operation. Alternatively, the functions of the loads may be derived over time. A consideration of the base speed and / or target speed can be omitted. The sum of the known loads can be directly proportional to a load torque, in particular to a load torque caused by the impact mode. The impact mode can be detected particularly reliably.

It is further proposed that the control unit contains a filter unit which is intended to carry out an unknown load from the operating parameter

Estimate filtering with a known frequency band. The filter unit may in particular have the function of a load estimator. In particular, the operating parameter can be processed by a bandpass filter. The unknown load can occur in a known frequency band. The bandpass filter can preferably suppress frequencies outside this frequency band. Effects of known loads with frequency spectrum deviating from the unknown load can be suppressed. The unknown load can be estimated by the bandpass filter from the operating parameter by filtering. The control unit can recognize the operating state of the impact mechanism. A complex calculation of the unknown load can be omitted.

It is further proposed that the control unit is provided to determine the operating state by comparing the estimated load with at least one limit value. In particular, an impact operation and / or the idling operation can be detected if the estimated parameter and / or a derivative of the estimated load exceeds or falls below the limit value.

It is further proposed that the control unit has a learning mode for determining at least one known load. In particular, in the learning mode, the control unit can learn constant loads, time-dependent loads and / or angle-dependent loads. The control unit may have predefined functions for the loads that have scaling parameters. In the learning mode, the percussion unit can set a speed signal in a time range and in an angular range over known time-dependent and angle-dependent period durations of functions stored for the loads and set the scaling parameters such that the sum of the known loads results in the smallest possible deviation from the speed signal. Preferably, a learning phase can be carried out in the idling mode, in which the operating state to be detected by the control unit does not occur. The known loads can be advantageously determined by the control unit. Loads that change over the lifetime of the percussion unit can be learned again. A determination of the loads by the user and / or by a person skilled in the art can be avoided.

It is proposed that the control unit has a dynamics model which is intended to estimate a drive torque of the drive unit. In particular, the control unit may have a dynamic model, which is intended to estimate a drive torque of the motor taking into account the current consumption of the motor. The dynamic model preferably takes into account a moment of inertia of the motor and / or the speed of the motor and / or a flux-dependent motor constant and / or a friction constant and / or a chained flow and / or a load torque and / or a viscous friction component and / or a turbulent friction component. The dynamics model can take into account further influences, in particular also time-periodic and angle-periodic influences. In this context, a "flow" is understood to mean an electromagnetic current in the motor

Flow depends in particular on the current consumption of the motor and on the flux-dependent motor constant. The flux-dependent motor constant can be defined by a characteristic curve. The characteristic curve can be calculated, for example, by means of a finite element model. The person skilled in the known methods, a dynamic model for calculating a drive torque of a

Motor, taking into account the current consumption and the speed to determine. Preferably, the dynamic model is provided to estimate the load torque of the motor and / or the drive unit. Preferably, the load observer of the control unit is designed as a Luenberger observer. Under a "Luenberger observer" is in this context, in particular a, the

Skilled in the art, which compares a value estimated with a model of the observer with an actually measured value. The difference may form a correction term of the simulated model. From the difference of the estimated value with the measured value, an unknown quantity can be estimated. In this context, a "size" is to be understood as meaning, in particular, a physical variable. <br/><br/> In particular, the model may be provided for estimating the rotational speed of the motor, taking into account the current consumption The Luenberger observer can compare the estimated rotational speed with the measured rotational speed A load torque correction term may be adjusted to minimize the difference between the estimated speed and the measured speed The load observer may estimate the load torque of the motor based on the load torque correcting element Additional parameters may be provided to determine the load torque These parameters can be selected by a person skilled in the art, in particular depending on a frequency spectrum of a parameter to be estimated The load torque can be suitable for detecting the operating state of the percussion mechanism. to recognize the impact mode. The control unit can process the load torque to detect the operating state. On sensors for measuring the load torque can be dispensed with. The percussion unit can be particularly robust and / or inexpensive. With the dynamics model, the load moment can be estimated very accurately. Dynamic effects and / or friction effects and / or a dependence of the motor constant on the electromagnetic flux can be taken into account. Preferably, the dynamics model can be implemented on the computing unit of the control unit. As an alternative to the Luenberger observer, one skilled in the art can also use another suitable method for determining a variable to be estimated from a deviation of the parameter estimated from the dynamic model from a measured parameter, for example a Kalman filter known to the person skilled in the art.

It is further proposed to determine model parameters of the dynamics model from a comparison of measured and estimated parameters. In particular, model parameters of the dynamics model can be determined in the learning mode. The learning mode is preferably performed in the idle mode of the percussion unit. The parameter to be estimated, in particular the load torque caused by the impact mode, can at least largely be dispensed with during idle operation. In this context, "at least largely" is to be understood in particular as meaning that the parameters to be estimated assume less than 30%, preferably less than 10%, of their value in the operating state to be detected, a difference of the value estimated with the dynamics model from the measured value, in particular In particular, faulty model parameters can be attributed to the skilled person Various methods are known for changing the model parameters in a learning mode such that the difference is minimized cause the estimated speed to converge to the measured speed, and it can be advantageously achieved that model parameters are automatically determined, and changes in the life of the impact unit may be taken into account.

It is further proposed that the control unit is provided to determine the operating state by comparing at least one estimated parameter with at least one limit value. The operating status can be output as a digital signal. In particular, an impact mode can be detected when an estimated parameter exceeds a threshold. The estimated parameter may in particular be an estimated load torque. Preferably, the estimated parameter is an estimated load torque caused by the impact operation. Preferably, a plurality of operating states can be assigned to the plurality of limit values, the estimated load torque. Preferably, a slope and / or a frequency of an amplitude of the load torque can be assigned to an operating state. In particular, when the frequency of the amplitude of the load torque occurs in a speed-dependent frequency band in the region of an expected impact frequency of the impact mechanism, the control unit can detect the impact mode. In this context, an "expected beat frequency" is to be understood as meaning, in particular, a beat frequency which occurs in the impact mode of the percussion mechanism due to the input speed through the given transmission ratios of the drive unit of the percussion mechanism be eliminated.

It is further proposed that the control unit is provided, in at least one operating state for a change from the idling operation to the impact operation, at least one operating parameter temporarily to one

Set start value. In this context, a "change" from the idling mode to the striking mode should be understood to mean starting the percussion unit from the idling mode The changeover into the striking mode can take place, in particular, when the striking mechanism is switched over from the idling mode to the striking mode. should in this

Connection in particular be understood by the percussion unit for the operation of the percussion generated and / or influenced parameters, such as a drive speed, an operating pressure or a throttle position. In this context, a "starting value" is to be understood as meaning, in particular, a stable operating parameter which leads to a reliable starting of the

Percussion is suitable. In this context, the term "reliable" is to be understood in particular as meaning that when the percussion mechanism is switched over from the idle mode to the beat mode, more than 90%, preferably more than 95%, more preferably more than 99% of the cases are used "should in this context in particular be understood as a limited period. In particular, the period may be shorter than 30 seconds, preferably shorter than 10 seconds, more preferably shorter than 5 seconds. It can be achieved a reliable start of the impact operation. Impact operation with operating parameters unsuitable for a percussion start can be possible. Operating parameters that are unsuitable for a percussion start can be permitted as labor values. An idle mode with unsuitable for a Schlagwerkstart operating parameters may be possible. Operating parameters that are unsuitable for a percussion start can be allowed as idle values. A reliability of the impact mechanism can be increased. An efficiency of the impact mechanism can be increased. It is proposed that the control unit is provided for setting the operating parameter to a supercritical work value in at least one operating state in a percussion mode. In particular, the control unit may be provided for setting a supercritical work value when a user requests a work value that is supercritical under given conditions. In this context, a "supercritical" work value should be understood to mean, in particular, an operating parameter in which a successful transition from idle operation to impact operation is not ensured In particular, in a percussive impact mode with a supercritical operating parameter, impact operation may be less than 50%, A relationship between the operating parameter and an impact amplitude of the racket or of another impact-generating component of the percussion mechanism may in particular comprise a hysteresis, a supercritical operating parameter being characterized in particular be that it exceeds or falls below a threshold value above or below which a function of the beat amplitude is ambiguous in dependence on the operating parameter A supercritical work value during an already successful impact operation may preferably be characterized by a stable continuation of the impact mode. A reliable Schlagwerkstart can preferably be done with a starting value. The starting value is preferably in a range of the operating parameter in which the function of the amplitude has a clear solution as a function of the operating parameter. A percussion performance may be increased at the supercritical operating parameter. A performance of a machine equipped with the percussion machine can be increased. A operation of the impact mechanism with the supercritical operating parameter may be permissible. Preferably, the hammer mechanism can be operated in the idling mode in the idling mode with an idling value corresponding to the supercritical starting value. Preferably, the operating parameter for starting the impact mechanism is temporarily set to the starting value. The impact mechanism can be operated in impact mode and in idle mode with the supercritical operating parameters. The impact mechanism can be operated in idle mode and in impact mode with the user-selected operating parameters. The user can recognize the selected operating parameters particularly well in idle mode. It is proposed that the operating parameter is a throttle characteristic of a venting unit. In this context, a "throttle characteristic" is to be understood as meaning, in particular, a setting of the venting unit which alters a flow resistance of the venting unit, in particular a flow cross section. The venting unit may in particular be provided for pressure and / or volume compensation of at least one room in the impact mechanism. In particular, the venting unit may be provided for venting and / or venting a space in a guide tube guiding the racket in the direction of impact in front of and / or behind the racket. Preferably, the operating parameter may be a throttling position of the venting unit of the space arranged in the direction of impact in front of the racket. If a flow cross section is increased in this venting unit, a vent of the space in front of the racket can be improved. A counterpressure against the direction of impact of the racket can be reduced. An impact strength can be increased. If a flow cross-section is reduced in this venting unit, a vent of the space in front of the racket can be reduced. A back pressure opposite to the direction of impact of the racket can be increased. An impact strength can be reduced. In particular, a return hollow movement of the racket against the direction of impact can be assisted by the back pressure. A start of the percussion can be supported. The operating parameter can ensure a reliable starting of the impact mechanism. The operating parameter with reduced flow area may be a stable operating parameter. It can be suitable as start value. The operating para- Meter with increased flow cross section may be a critical operating parameter with increased hammer performance. It can be suitable as a labor value. In an advantageous embodiment of the invention it is proposed that the

Operating parameter is a beat frequency. In this context, a "beat frequency" is to be understood as meaning an average frequency with which the percussion mechanism generates beat pulses in the percussion mode, the beat frequency in particular being dependent on a percussion clock speed

Speed of an eccentric gear to be understood, which moves a piston of the percussion. The piston may in particular be provided to generate a pressure pad to pressurize the racket. The racket can be moved in particular by the pressure pad generated by the piston with the beat frequency. The beat frequency and percussion speed are preferably directly related. In particular, the amount of beat frequency 1 / s may be the amount of hammer speed U / s. This is the case when the bat performs one stroke per revolution of the eccentric gear. As a result, the terms "frequency" and "speed" are therefore equivalently used. The person skilled in the art will adapt the following explanations correspondingly to deviations of a percussion mechanism from this context. The striking mechanism speed can be set particularly easily by the control unit. A percussion speed can be particularly suitable for a machining case. The striking mechanism can be particularly powerful at a high percussion speed. The drive unit of the impact mechanism can be operated at a higher percussion speed with a higher speed. A driven by the drive unit ventilation unit can also be operated at a higher speed. Cooling of the hammer mechanism and / or the drive unit by the ventilation unit can be improved. A function of the beat amplitude of the

Impact can be dependent on the percussion speed. At a speed above a threshold speed, the function may have hysteresis and be ambiguous. A start of the beat mode when switching from the idle mode to the beat mode and / or a restart of the beat mode after an interruption of the beat mode can be unreliable and / or impossible. be borrowed. A percussion speed below the limit speed can be used as a starting value and / or labor value for a stable impact operation. A percussion speed above the limit speed can be used as a work value for a critical impact operation. Above a maximum speed, impact operation may be impossible and / or unreliable. By "unreliable" is meant in this context in particular that the impact operation repeatedly and / or arbitrarily fails, in particular at least every 5 minutes, preferably at least every minute.

Further, an operation change sensor is proposed, which is intended to signal a change of an operating mode. In particular, the operating change sensor of the control unit can signal a change from the idle mode to the beat mode. The operating change sensor can be provided to detect a contact pressure of a tool on a workpiece. It can be advantageously recognized when the user begins a machining operation. Particularly advantageously, the change-of-operation sensor can detect a switching over of the percussion mechanism, in particular an opening and / or closing of idling openings and of further openings of the percussion mechanism, which are provided for a change of operating mode. The operation change sensor can detect a displacement of a Leerlauf- and / or control sleeve, which is provided for the operating mode change of the impact mechanism. The control unit can advantageously detect when a mode change of the impact mechanism takes place. The control unit may advantageously alter the operating parameter to assist and / or facilitate the operating mode change. The impact mode can be reliably started.

Next, a hand tool, in particular a drill and / or percussion hammer, proposed with a percussion unit according to the invention. The hand tool may have the advantages described.

Furthermore, a control unit of a percussion unit with the described properties is proposed. A percussion unit with the control unit can have the described advantages. The control unit can be retrofitted to an existing control unit. Furthermore, a method with a percussion unit with the described properties is proposed. The method may be particularly suitable for determining operating parameters.

A preferred control unit comprises a memory unit in which a program and / or parameters and / or values describing the aforementioned method for executing the aforementioned method can be retrievably stored, and a computer unit for carrying out the aforementioned method or the aforementioned program.

Drawing Further advantages emerge from the following description of the drawing. In the

Drawing four embodiments of the invention are shown. The drawing, the description and the 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.

Show it:

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

2 shows a schematic representation of the hammer and percussion hammer in a striking mode,

3 is an illustration of a flowchart of the control unit in an operation of a striking mechanism,

Fig. 4 is an illustration of a flowchart of the control unit in a

Learning mode,

5 shows an illustration of parameters which influence a speed signal, FIG. 6 shows a representation of parameters learned in the learning mode,

7 shows a schematic representation of a possible definition of a start value, a limit value, a work value and a maximum value, 8 is an illustration of a flowchart of the control unit of the percussion mechanism unit when changing between an idle mode and a beat mode;

9 shows a representation of signal spectra of a hammer and percussion hammer in a second exemplary embodiment in various operating states,

10 is a schematic representation of a hammer and percussion hammer in a third embodiment in an idle mode,

1 is a representation of a block diagram of a load observer,

12 shows a representation of a system with the load observer and a drive unit,

13 is an illustration of a motor characteristic,

14 is an exemplary illustration of an estimated and a measured load torque,

15 is an exemplary illustration of the course of the measured and the estimated load torque and an operating state of a striking mechanism,

Fig. 16 is a schematic representation of a venting unit of a striking mechanism of a hammer and percussion hammer with a percussion unit in a fourth embodiment and

Fig. 17 is a further schematic representation of the ventilation unit.

Description of the embodiments

Figure 1 and Figure 2 show a drill and percussion hammer 12a with a percussion unit 10a and with a control unit 14a, which is intended to control a pneumatic percussion 16a and regulate. The percussion unit 10a includes a motor 36a with a gear unit 38a, which rotatably drives a hammer tube 42a via a first toothed wheel 40a and drives an eccentric gear 46a via a second toothed wheel 44a. The hammer tube 42a is rotatably connected to a tool holder 48a, in which a tool 50a can be clamped. The tool holder 48a and the tool 50a may be driven for a drilling operation via the hammer tube 42a with a rotating working motion 52a. When a racket 54a is in an impact mode accelerates an impact direction 56a in the direction of the tool holder 48a, it exerts a shock pulse in an impact on a between the racket 54a and the tool 50a arranged firing pin 58a, which is passed from the firing pin 58a to the tool 50a. The tool 50a exerts a beating working movement 60a by the impact pulse. A piston 62a is also movably mounted in the hammer tube 42a on the side of the racket 54a facing away from the direction of impact 56a. The piston 62a is moved periodically in the hammer tube 42a in the direction of impact 56a and back again by means of a connecting rod 64a from the eccentric gear 46a driven by a hammer mechanism speed 124a (FIG. 8). The piston 62 a compresses between the

Piston 62 a and the racket 54 a in the hammer tube 42 a trapped air cushion 66 a. Upon movement of the piston 62a in the direction of impact 56a, the racket 54a is accelerated in the direction of impact 56a. The impact mode can start. By a rebound on the firing pin 58a and / or by a by the return movement of the piston 62a against the direction of impact 56a between the piston 62a and the racket 54a resulting negative pressure and / or by a back pressure in a striking space 134a between the racket 54a and the firing pin 58a the racket 54a are moved back against the direction of impact 56a and then accelerated again in the direction of impact 56a for a next impact pulse. In a region between the racket 54a and the firing pin 58a, vent holes 68a are arranged in the hammer pipe 42a, so that the air trapped between the racket 54a and the firing pin 58a in the hammer room 134a can escape. In an area between the racket 54a and the piston 62a, idling openings 70a are arranged in the hammer pipe 42a. The tool holder 48a is slidably mounted in the direction of impact 56a and is supported on a control sleeve 72a. A spring element 74a exerts a force on the control sleeve 72a in the direction of impact 56a. In a striking mode (FIG. 2) in which the tool 50a is pressed against a workpiece by a user, the tool holder 48a, against the force of the spring element 74a, displaces the control sleeve 72a so as to cover the idling openings 70a. If the tool 50a is set down from the workpiece, the tool holder 48a and the control sleeve 72a are displaced in the direction of impact 56a by the spring element 74a such that openings 76a of the control sleeve 72a come to lie above the idling openings 70a and clear passages. A pressure in the air cushion 66a between piston 62a and racket 54a may escape through the idle openings 70a. The racket 54a is not or only slightly accelerated by the air cushion 66a in an idle mode (Figure 1). In an idling mode, the racket 54a exerts no or only small impact pulses on the firing pin 58a. The hammer 12a has a hand tool housing 78a with a handle 80a and an auxiliary handle 82a on which it is guided by the user.

The control unit 14a has a load estimator 18a. The load estimator 18a is integrated in the control unit 14a. The control unit 14a is provided to detect an operating state of the striking mechanism 16a. The control unit 14a is provided to process at least one operating parameter. The control unit 14a is provided to process the operating parameter as a function of at least one known load and at least one load to be estimated. The load estimator 18a of the control unit 14a is provided to estimate an unknown drive load f _L by means of a measured engine speed ω of the motor 36a. The unknown drive load f _L is an unknown load torque M _L acting on the motor 36a

A total moment M denotes the sum of all moments acting on the motor 36a. M includes a drive torque of the motor A / _M and the unknown load torque M _L. J is the rotational inertia of all of the ω rotating parts of the motor 36a, the gear unit 38a and the eccentric gear 46a taking into account the gear ratios. It then applies the spin set:

The total moment M is the sum of a moment M _{M of} the motor 36a and of moments M _Li of loads acting on n motor 36a:

The engine speed ω can be represented as a function of the time ω (ί), which is composed of a non-changing or only slowly changing basic speed ω ₀ and rapidly changing, highly dynamic portions f, (t) and the desired drive load f _L : The functions f, (t) describe known loads. This equation is obtained by an integration of the spin set, the functions f therefore do not have the dimension of a torque and are therefore denoted by the letter f instead of M. This procedure is known to the person skilled in the art. The load to be estimated can be determined by subtracting the known quantities from the measured engine speed w (t). f _M (t) is the function of the moment M _{M of} the motor 36 a:

^ = ω (ί) -ω ₀ - ^ (- ^ (- ^ (-) The known load components f, - (t) describe in particular speed fluctuations by variable transmission ratios, by motor irregularities and a non-uniform voltage supply, eg by a motor control A time-periodic load f, (t) may be, for example, a voltage fluctuation, in particular at twice the mains frequency of a power supply of the hammer and percussion hammer 12a, an angular periodic load fi (Φ) may for example be a translation which changes with a rotational position of the eccentric gear 46a. The person skilled in the art will store loads whose course is exactly known as a calculation rule on the control unit 14a.

The control unit 14a is provided to detect the operating state of the striking mechanism 16a. FIG. 3 shows a flowchart of the control unit 14a during operation of the hammer mechanism 16a. An input is the measured engine speed ω. In a first step 94a, depending on a sensor used, a sensor compensation can take place. From the measured engine speed ω, a mean speed is determined in a further step 96a. In a further step 98a, a difference of the measured engine speed ω and the average speed is determined. Time periodic loads f, (t) are subtracted in a next step 100a and angular periodic loads f, (Φ) in a next step 102a. Optionally, in a step 104a further

Input variables calculated influencing variables 84a are deducted. The result is the course of the load f _L to be estimated, which can be further analyzed and / or filtered in a further step 106 a. In particular, patterns, in particular a periodicity with an expected beat frequency, can be used. to be worked. The estimated load is output as the load size 86a. The operating state is determined by a comparison of the load size 86a with a limit value. The control unit 14a can determine the operating state of the impact mechanism 16a by this comparison, in particular the impact mode and the idling mode.

FIG. 4 is an illustration of a flowchart of the control unit in a learning mode for detecting known loads. The measured engine speed ω is calculated as a function of time t (time domain) w (t) in time base and as an angle-based function of angle φ (angular range) ω (φ). In an angular range, in particular periodic influences, which are dependent on the rotational position of the eccentric gear 46a and / or the motor 36a, can be detected. w (t) is averaged over a period of f (t) in step 108a. The result is the learned course of the known load f (t). ω (Φ) is in a step 1 10a over the periods Φ ₂ νοη ΐ ₂ (Φ) and in one step

1 12a over the period Φ ₃ of ΐ ₃ (Φ) averaged. The result is the learned curves of the known loads ΐ ₂ (Φ) and ΐ ₃ (Φ). The period lengths on an angle basis Φ are dependent on the gear ratios of the influences that cause these loads to the engine speed ω. Depending on the number of angular periodic and time-periodic known load components that are taken into account, these are determined in the manner described from the measured engine speed ω. The person skilled in the art will determine the number of loads f, to be learned appropriately. A larger number / ^' increases the accuracy of the determination of the load to be estimated f _L , which increases the cost of calculating and determining and / or learning the loads. Learning advantageously takes place in the idle mode without the influence of the load f _L to be estimated. The determination of the known loads f; in the learning mode is further explained in the following figures 5 and 6.

FIG. 5 shows a representation of parameters which influence the measured engine speed ω. The parameters are the loads f (t), ΐ ₂ (Φ) and ΐ ₃ (Φ). In the lowest

Diagram 174a shows the course of the measured engine speed w (t) in the time domain, which contains the influence of loads f i. The diagrams 176a, 178a, 180a show, from bottom to top, curves of two angle-periodic loads ΐ ₂ (Φ) and ΐ ₃ (Φ) with different period duration and a time-periodic load f (t). In the top diagram 182a, the course of the Basic speed ω ₀ shown. The basic speed ω ₀ remains unchanged over a longer period of time and can take on a new value when changing the operating mode. The base speed ω ₀ , for example, corresponds to a speed command value of the motor 36 a for a desired beat frequency. FIG. 6 shows a representation of the courses of parameters learned in the learning mode. The learned parameters are the profiles of the learned loads fi (t), f ₂ (<P) and f ₃ (<P). In the uppermost diagram 184a the measured engine speed w (t) is shown in the time domain. These are shown in diagram 186a by averaging over the period t-1 of fi (t), in diagram 188a by averaging over the period Φ ₂ νοη f ₂ (<P) and in diagram 190a by averaging over the period

Φ ₃ learned from f ₃ (<P) curves of the loads fi (t), f ₂ (<P) and f ₃ (<P) shown. In the present example, the period Φ ₃ νοη f ₃ (<P) is one revolution of the motor 36a, and the period Φ ₂ νοη f ₂ (<P) is one rotation of the eccentric gear 46a. The control unit 14a is provided for temporarily setting at least one operating parameter to a starting value 28a in at least one operating state for a change from the idling operation to the striking operation. The starting value 28a may in particular be a beat frequency at which a reliable percussion start is possible. FIG. 7 shows a striking energy E as a function of the frequency f and a possible definition of the starting value 28a, a cut-off frequency 128a, an operating frequency 130a and a maximum frequency 132a of the striking frequency of the striking mechanism 16a. Below the cutoff frequency 128a takes place at a

Operating mode change into the beat mode a reliable percussion start instead. If the percussion frequency in the percussion mode is increased from a value below the cutoff frequency 128a into the range between the cutoff frequency 128a and the maximum frequency 132a, the striking mechanism will remain in percussion mode as the impact energy E increases. A change from idle operation to impact operation remains above the cut-off frequency 128a or occurs only in a few cases; the racket 54a may be starting from the idle mode of

Movement of the piston 62 a not or hardly follow. Above the maximum frequency 132a, percussion stops in most cases. For the impact mode, a working frequency 130a can be set after the striking mechanism has been started and thus the performance of the hammer mechanism 16a against operation below the cutoff frequency 128a can be increased. A beating frequency or percussion speed 124a above this maximum frequency 132a is unusable. The percussion speed 124a corresponds to the speed of the Exzen- tergetriebes 46a and thus the beat frequency. Optionally, an idle value

90a for the idling operation, which is advantageously higher than the starting value 28a and lower than the operating frequency 130a.

An operation change sensor 34a is provided to signal a change of the operation mode. The operation change sensor 34a transmits to the

Control unit 14a a signal 92a (Figure 8), when the control sleeve 72a is shifted so that the idling openings 70a are closed and the percussion mechanism 14a changes from the idle mode to the beat mode. In particular, if a beat rate is selected which is higher than a start value 28a, with which a reliable percussion start is possible, the control unit 14a first lowers the beat frequency to the start value 28a. If the change from idle operation to impact operation and / or a percussion start is detected with the aid of the load estimator 18a, the control unit 14a sets the beat frequency to the selected beat frequency. FIG. 8 shows a flow chart of the operation of percussion unit 10a. The

Diagram 166a shows the signal 92a of the operation change sensor 34a, where the value "1" indicates the impact mode The impact mechanism 16a has changed from the idling mode to the impact mode if the operation change sensor 34a signals the change of the operation mode the percussion frequency corresponding percussion speed 124a.

The hammer speed 124a and the engine speed w (t) are used equivalently herein; For concrete numerical values, a translation between motor 36a and eccentric gear 46a must be taken into account. The setpoint value of the percussion speed 124a is lowered to the start value 28a when the beat mode is detected. Diagram 168a shows a signal 88a of the load estimator 18a, with the value "1" signaling the impact mode. As impact action commences, the hammer set point 124a setpoint is raised to the percussion speed 124a corresponding to the operating frequency 130a, with a deceleration parameter determining a slope slope Now the impact operation until the operation change sensor 34a signals the change to the idling mode. The bottom diagram 172a shows the engine speed u) (t). The following description and the drawings of further embodiments are essentially limited to the differences between the exemplary embodiments, reference being made in principle to the drawings and / or the description of the other exemplary embodiments with respect to identically named components, in particular with regard to components having the same reference numbers , To distinguish the embodiments, instead of the letter a of the first embodiment, the letters b, c and d the reference numerals of the other embodiments followed.

FIG. 9 shows a representation of signal spectra of a drilling hammer and percussion hammers which are not shown in more detail here. The drill and hammer contains a

Impact unit in a second embodiment, which differs from the previous embodiment in that a load estimator includes a filter unit, which is designed as a bandpass filter. The bandpass filter suppresses portions of a speed signal outside a known frequency band excited by a beat frequency. The beat frequency corresponds to one

Speed of a Exzentergetriebes, which drives a piston of a percussion. The beat frequency excites vibrations with the beat frequency itself and / or vibrations with a multiple of the beat frequency. A suitable frequency band that can pass through the bandpass filter is therefore in the range of the beat frequency or a multiple of the beat frequency. The beat rate is in the range of 15Hz - 70Hz depending on user settings. In FIG. 9, a beat frequency of 40 Hz is set. This frequency is not visible in the signal spectrum 156b during a beat operation. Clearly visible in the drill and percussion hammer of the second embodiment in the signal spectrum 156b a clear maximum 162b with five times the beat frequency at 200Hz. In the signal spectrum 158b in idling mode this is almost completely eliminated. In this embodiment, therefore, a center frequency 164b of a frequency response 160b of the band-pass filter is set to 5 times the beat frequency. The center frequency 164b corresponding to an adjustment of the beat frequency, or the speed of the eccentric changed. The clear maximum 162 b at five times the beat frequency in impact mode is suitable for determining an operating state of the impact mechanism, in particular an idling mode and the impact mode. If a signal applied to an output of the bandpass filter and filtered by the bandpass filter exceeds a specified threshold, the beat operation is detected. The person skilled in the art will suitably set the threshold value, the center frequency 164b and a bandwidth of the bandpass filter in experiments. In the exemplary embodiment, the threshold value can be set via a control element, not shown in detail.

FIG. 10 shows a drilling and percussion hammer 12c with a hammer mechanism unit 10c, with a control unit 14c and a percussion mechanism 16c in a third exemplary embodiment. The percussion unit 10c differs from the first embodiment in that a load estimator 18c is designed as a load observer 20c. The load observer 20c has a dynamic model which is intended to estimate a load torque M _{L of} a motor 36c of a drive unit 30c (FIG. 10). The load observer 20c determines the load torque M _L from an engine speed ω and a motor current / ^'of the motor 36c of the drive unit 30c (FIG. 11). FIG. 12 shows a system with the load observer 20c and the drive unit 30c operated with a voltage U. The load observer 20c estimates using a simulation member 122c of the dynamics model and the

Correction element 192c the load torque M _L using the motor current / and the engine speed ω. The basis of the load observer 20c is a model of the motor 36c as the basis of the estimation algorithm:

J _M - = ο (Ψ) / ^' - M _L - e - ao - ba> ²

Here, J _{M is} the mass moment of inertia of the motor 36c, ω the motor speed of the motor 36c, c the flux-dependent motor constant, ψ the concatenated flux, M _L the load torque acting on the motor 36c, e a constant frictional portion,> viscous frictional portion and öaj ² turbulent friction component.

FIG. 13 shows a characteristic curve ο (ψ) ί = c (i) of a flux-dependent motor constant for determining the drive torque M _{M as a} function of the motor current / ^' . The driving torque M _M is the moment that a polluter through the motor / ^' gently applies magnetic force to the motor 36c. This characteristic can be determined by means of a finite element model of the motor 36c or in another manner known to the person skilled in the art. In the case of a DC motor, the motor constant is constant and does not depend on ψ, so this connection is simplified.

It is assumed that a load moment M _{L changes} only slowly over time, that is to say that approximately:

dM _ _L _Q

dt

The load observer 20c is known as a Luenberger

An observer is trained in which the estimated by the simulation member 122 c of the dynamics model engine speed ω of the motor 36 c is compared with the actual speed. In the following equation of a dynamics of the observer in which the constant and the turbulent frictional component are neglected, the estimated states are denoted by co, M:

CKSS

J _M - = c ( ^x ¥) i - M _L - θώ + Ι ^ ω -ώ)

dt

dM _{L Λ}

- = \ _Ί (co -ω)

dt ²

Ii and l ₂ represent correction elements 192c of the load observer 20c. By a suitable choice of the coefficients and l ₂ , the observer dynamics of the observer can be influenced, that is to say, the speed at which a

Deviation the estimated engine speed co with the measured engine speed ω converges. The person skilled in the art will select a suitable observer dynamics in order to be able to recognize an influence of the part of the load torque M _L which is caused by an operating state to be recognized. It is advantageous to choose an observer dynamics which corresponds at least to the duration of a movement cycle of a piston 62c and / or a beating cycle of a racket 54c of the striking mechanism 16c. That estimated by the load observer 20c

Load torque M _L in this case corresponds to an average value of a load torque M _L applied to the motor 36c during a beating cycle. This mean value is significantly influenced by a piston movement and differs significantly in an impact mode and in an idle mode of the percussion mechanism 16c. Techniques for determining the coefficients and l ₂ for the interpretation of the observer dynamics are known in the art. If the load torque M _{L exceeds} a threshold value, an impact mode can be detected. Next, a course of the load torque M _{L is} recorded by the control unit 14c. From a long-term trend of the load torque M _L can be concluded that a service condition of the hammer and percussion hammer 12c. An increase in the average load torque M _L , in particular in idle mode, is an indication of increasing internal friction of the hammer and percussion hammer 12 c. This is an indication of contamination, inadequate lubrication or other signs of wear. A service light, not shown here, signals a user a recommended service of the hammer and percussion hammer 12c as soon as a limit value of the average load torque M _{L is} exceeded and / or the average load torque M _L rises sharply in a period of time. In the exemplary embodiment, a recommended service is signaled if the mean load torque M _L in idle mode is more than 50% higher than a reference value.

FIG. 14 shows an example of the course of the actual load torque M _L and of a load torque M _L estimated by the load observer 20c. The load observer 20c is implemented with advantage on the control unit 14c. The estimated load torque M _L can be used on the control unit 14 c as an input variable of a control algorithm, for example for controlling the motor 36 c. In impact mode, the load torque M _{L increases} by a periodically changing air pressure of an air spring between the racket 54c and the piston 62c, so that the air pressure can be estimated using the load torque M _L. A control algorithm of the motor 36c can thus take into account the air pressure of the air spring. The period corresponds to the beat frequency and the speed of an eccentric gear 46c. A measurement of the load torque M _L can be omitted. Advantageously, the load observer 20c is implemented for calculation on a digital signal processor of the control unit 14c in time-discrete form. The equations are transformed by a Tustin approximation known to the person skilled in the art (bilinear approximation). The operating condition is determined by comparing the estimated load with at least one threshold 26c. 15 shows in the upper diagram 1 14c a curve of the load torque M _L , in the middle diagram 1 16c a profile of the load observer 20c estimated load torque M _L and in the lower diagram 1 18c an operating state representing signal 92c, wherein a value of "1" the operating state "impact mode" and a value of "0" corresponds to the operating state "idle mode". The observer dynamics are chosen so that the estimated load torque M _L is converged during the time period of a beat cycle, so that the estimated load torque M _L corresponds to a smoothed estimated load torque M _L. The limit value 26c is set such that when the estimated load torque M _{L is} compared with the limit value 26c, the estimated load torque M _L in the impact mode is greater than the limit value 26c, and in the idle mode is less than the limit value 26c. In the example, the limit value 26c is half of the mean estimated load torque M _L in impact mode. Due to the smoothing of the estimated load torque M _L due to the selected observer dynamics, the estimated load torque M _L remains during the

Impact mode permanently above the threshold 26c. The control unit 14 c further contains a safety circuit which, when a maximum value 126 c of the estimated load torque M _{L is} exceeded, the drive unit 30 c of the

Schlagwerks 16c switches off due to overload.

FIG. 16 and FIG. 17 show a percussion unit 10d for a drilling and percussion hammer 12d in a further exemplary embodiment. The impact mechanism unit 10d differs from the preceding impact mechanism unit in that an operating parameter defined by a control unit 14d is a throttle characteristic of a ventilation unit 32d. A striking space in a hammer tube 42d is limited by a striker and a club. The venting unit 32d has in the hammer tube 42d ventilation openings for venting the whipping room. The venting unit 32d serves for a

Pressure equalization of the striking area with an environment of a striking mechanism 16d. The venting unit 32d has an adjustment unit 136d. The adjustment unit 136d is intended to influence a venting of the striking space 56d in front of the racket during a striking operation. The hammer tube 42d of the striking mechanism 16d is mounted in a gear housing 138d of the hammer and percussion hammer 12d. The gear housing 138d has ribs 140d arranged in a star shape and facing an outer side of the hammer tube 42d. Between hammer tube 42d and gear housing 138d, a bearing bush 142d, which supports the hammer tube 42d on the gear housing 138d, is pressed into an end region 144d facing an eccentric gear. The bushing 142d forms with the ribs 140d of the transmission housing 138d air ducts 146d, with the vent holes in the hammer tube

42d communicate. The air channels 146d form part of the venting unit 32d. The striking space is connected via the air ducts 146d with a gear chamber 148d arranged behind the hammer pipe 42d against the direction of impact 56d. The air channels 146d form throttle bodies 150d, which have a flow cross-section of the connection of the hammer chamber with the gear compartment

148d influence. The adjusting unit 136d is provided to adjust the flow area of the throttles 150d. The throttle passages 150d forming air passages 146d form a transition between the hammer room and the gear room 148d. An adjusting ring 194d has star-shaped, inwardly directed valve extensions 154d. Depending on a rotational position of the adjusting ring 194d, the valve extensions 154d may completely or partially cover the air passages 46d. By adjusting the adjusting ring 194d, the flow cross section can be adjusted. The control unit 14d adjusts the adjusting ring 194d of the adjusting unit 136d by rotating the adjusting ring 194d by means of a servo drive 120d. If the venting unit 32d is partially closed, the pressure in the striking area arising during a movement of the striker in the direction of impact 56d can escape only slowly. It forms against the movement of the racket in the direction of impact 56d directed back pressure. This back pressure supports a return movement of the racket against the direction of impact 56d and thus a Schlagwerkstart. Is for the

Schlagwerkdrehzahl a supercritical work value chosen in which no reliable Schlagwerkstart is possible with the vent unit open 32d, the control unit 14d closes the idle operation in the impact mode, the vent unit 32d partially. The back pressure in the impact chamber supports the start of impact operation. After completion of the percussion start, the control unit 14d opens the vent unit 32d again. The control unit 14d may also use the operating parameter of the throttle characteristic of the venting unit 32d for power regulation.

Claims

claims

1 . Impactor unit, in particular for a drilling and / or percussion hammer (12a, 12c, 12d), with a control unit (14a, 14c, 14d), which is intended to control a pneumatic percussion mechanism (16a, 16c, 16d) and / or to be regulated, characterized in that the control unit (14a, 14c, 14d) has at least one load estimator (18a; 18c; 18d).

2. percussion unit according to claim 1, characterized in that the

Load estimator (18c) as a load observer (20c) is formed.

3. percussion unit according to claim 1 or 2, characterized in that the control unit (14a, 14c, 14d) is provided to detect an operating state of the percussion mechanism (16a; 16c; 16d).

4. percussion unit according to one of the preceding claims, characterized in that the control unit (14a, 14c, 14d) is provided to process at least one operating parameter.

5. percussion unit according to claim 4, characterized in that the

Control unit (14a, 14c, 14d) is provided to process the operating parameter as a function of at least one known load and at least one load to be estimated.

6. percussion unit according to claim 5, characterized in that the

Control unit (14a; 14c; 14d) includes a filter unit which is arranged to estimate an unknown load f _L from the operating parameter by filtering with a known frequency band.

7. percussion unit according to claim 5 or 6, characterized in that the control unit (14a) is provided to determine the operating state by comparing the estimated load with at least one limit value (26c).

8. percussion unit according to one of the preceding claims, characterized in that the control unit (14c) has a learning mode for determining at least one known load.

9. percussion unit at least according to claim 2, characterized in that the control unit (14c) has a dynamic model, which is intended to estimate a drive torque of a drive unit (30c).

10. percussion unit according to claim 9, characterized in that the

Control unit (14c) is provided to determine model parameters of the dynamics model from a comparison of measured and estimated parameters.

1 1. Impact unit at least according to claim 9, characterized in that the control unit (14c) is provided to determine the operating state by comparing at least one parameter with at least one limit value (26c).

12. percussion unit according to one of the preceding claims, characterized in that the control unit (14a) is provided to temporarily adjust at least one operating parameter to a start value (28a) in at least one operating state to a change from a no-load operation to a percussion operation.

13. percussion unit according to claim 12, characterized in that the

Operating parameter is a throttle characteristic of a vent unit (32d).

14. percussion unit at least according to claim 12, characterized in that the operating parameter is a beat frequency.

15. percussion unit according to one of the preceding claims, characterized by an operating change sensor (34 a) which is provided to signal a change of an operating mode.

16. Hand tool, in particular drilling and / or percussion hammer, with a percussion unit (10a, 10c, 10d) according to one of the preceding claims.

17. Control unit of a percussion mechanism unit (10a, 10c, 10d) according to any one of claims 1-15.

18. A method with a percussion unit (10a, 10c, 10d) according to one of claims 1-15.