EP1466702A1 - Control of a power tool - Google Patents

Abstract

The hammer drill (1), provided with a tool clamping device (2) and a switch (5) located at the handle (4) activating the connection between the power lead (6) and the drive unit (7), is additionally fitted with a sensor (8). The sensor (8) is positioned between the chucks (2) and the handle (4) in order to monitor the pressure applied on the tool (1) by the user and directed to the work-piece. After the working modus is selected by using a control switch (9) any negative influences are corrected automatically.

Description

The invention refers to a controller for an at least partially rotating Electric hand tool machine like a combi hammer.

Usually have electric hand tool machines workpiece side of a handle a regulator switch, which usually the index finger one, the handle comprehensive, leading hand of the user is assigned. This regulator switch closes on actuation, on the one hand, the circuit via the electric motor to the mains and controls on the other hand, depending on the Eindrückiefe an electronic control of the electric motor at.

The movement of the index finger when operating the workpiece side of the handle arranged pressure switch for activating the connection of the electric motor to Power source is with the for safe guidance of a rotating Electric hand tool by the user's hand necessary gripping reflex to the Handle intuitively correlates and thus represents the willingness of the user to activate the Electric motor safe. However, the user must both the contact pressure for fine work the electric hand tool machine to the ground as well as his finger position on Carefully control the controller switch by motor. This requires on the one hand motor Skill, on the other hand also a certain degree of concentration, which in particular in monotonous activities in the construction industry is not necessarily constantly given.

According to DE19534850 has a rotating electric hand tool a Regulator switch, which when actuated the circuit via the electric motor for Power supply closes and activates a control electronics of the electric motor, which in Depending on a force measured on an internal sensor, the speed of the Electric motor to a maximum reaction torque controls. At US2001 / 0025421 and DE19738092 is activated after activation with the index finger Regulator switch the setpoint speed of the control of the electric motor in response to a, on a force sensor accessible with the thumb, force consciously changed. Intuitively given by the handling of the electric hand tool machine itself Control commands are not taken into account by such regulations.

According to DE4401664 has a rotating and beating electric hand tool a different depending on the selected operating mode control of the electric motor.

After W00219048 has a rotating and beating electric hand tool a depending on the selected operating mode optimal control of the operating condition with respect Speed, impact frequency and contact pressure by many parameters sensed by the sensor, including the forces acting on the electric hand tool machine, in an adaptive Process analysis are evaluated. This optimization takes place exclusively in the Maximization of drilling progress.

According to DE10034359 has a beating electric hand tool for control the impact amplitude on a contact force sensor. According to DE4306524 has a rotating electric power tool on a contact pressure sensor, which via a Regulation controls the speed or torque intuitively pressure-dependent. The after the Activation via a Mindestandruck carried out automatic activation can be a for lead the user unexpected twisting of the electric hand tool. Of Furthermore, for many applications in the construction industry, for example, color mixing, can sinking, Borehole lengthen a pressure-dependent control undesirable.

According to US5014793 has a rotating electric hand tool on the workpiece side on a handle a motionless trigger switch with force sensor, which after an initial actuation by the index finger activates the automatic speed control, which depends on the force of the index finger on the trigger switch. The over the Forefinger applied force requires a motor control of the user who with the handling of the electric hand tool machine is not intuitively correlated.

The object of the invention is the realization of a secure, intuitive control an at least partially rotating electric hand tool.

The object is essentially achieved by the features of the independent claims. Advantageous developments emerge from the subclaims.

Essentially, an at least partially rotating electric hand tool machine with a tool holder for a tool a workpiece side of a handle arranged, advantageously this workpiece side only partially covering, pressure switch for activating the connection of a power source with an electric motor, which with a control electronics is connected, which is connected to a force sensor, the between the tool holder and the handle for measuring a contact force of the Electric hand tool machine is designed and suitably arranged against a workpiece.

By the trained for measuring the contact force against a workpiece force sensor Intuitively safely via the grip flex activated electric motor and its control intuitively correlated with the handling of the electric hand tool.

Advantageously, the pressure switch is designed as a discrete switch, whereby its discrete Switching states can be used directly to control the control electronics.

Advantageously, the control electronics are controllably connected to a mode selector switch, whereby at different selected operating modes of the control electronics different Control programs are selectable.

Advantageously, the electric hand tool has an axially limited movable Impact element, which with respect to the tool holder axially by a maximum of 1 mm displaceable, which mediates with the by the contact force dependent control Abandonment of an otherwise necessary mechanical impact shutdown over a switching path of the striking element greater than 1 mm, the axial play in the Tool holder is reduced and thus a more precise attachment and work in the Operating Modes << Drill Chisels >> and << Chisels >> is enabled.

In a first at least partially rotating operating mode assigned Control method is in a first step by pressing the pressure switch s Control is activated, which in a second step, the electric motor depending on a the force measured by the force sensor controls which with the contact pressure of the Electric hand tool machine is correlated against the workpiece.

By the intuitive control of the electric hand tool on the Contact force separate activation of the control by pressing the pressure switch the required readiness of the user to safely guide a rotating Electric hand tool machine detected.

Advantageously, in the second step, the sensitivity of the controller with respect to the Force sensor measured force depending on an activation period of the second Step, further advantageous degressive with respect to the activation period, whereby the Electric hand tool machine in an optimal for drilling operation mode << LowPowerDrilling >> sensitively reacts to the contact pressure.

Advantageously, in the second step, the controller always controls the electric motor above one Minimum speed, which is optional depending on the operating mode, thereby providing for the user the activity of the control by a movement of the tool is reliably recognizable.

Advantageously controls at a negative force measured by the force sensor in the second Step controlling the electric motor proportional to the amount of negative force, whereby the pulling force required to pull the tool out of the workpiece causes a rotary drive to prevent jamming of the tool.

Advantageously, in a third step in discharge of the pressure switch, the controller disabled, which stops the control intuitively when the clasping of the leading hand loosens around the handle.

It is advantageous in a selected by the mode selector second mode of operation in second step, the electric motor regardless of the force measured by the force sensor controlled, which in particular for a mode of operation << Highspeed >> with maximum Speed is advantageous.

Advantageously, in a non-rotating second operating mode in the first step, the Activation of the control by a, in a trigger period of maximum 0.5 s, triggering operation / discharge of the pressure switch, whereby the activation via a Click occurs and thus during the second step, the pressure switch is not permanent must be pressed and thus in particular the index finger in the operating mode << Meissein >> is relieved.

Advantageously, in a non-rotating second operating mode in the third step a triggers to the first step alternately repeated triggering operation of the pressure switch over a period of a maximum of 0.5 s, the control is disabled, causing the Operating mode << Chisels >> is ended intuitively by a repeated click.

Alternatively advantageously takes place in a non-rotating second operating mode the Activation of the control in the first step with a measured force peak greater than one Activation force, advantageously within a trigger period of less than 0.5 s, whereby in the operating mode << chisel >> a << kickstart >> is realized.

Advantageously, in a non-rotating second operating mode in the third step, the Control deactivated if the measured force is always lower over an idle period as a minimum force, allowing in this mode of operation an intuitive shutdown by << TimeOut >> takes place, which in particular in a beating operating mode the Shutdown generation of beats. One to prevent blanks otherwise necessary impact shutdown, which usually mechanically over a sufficiently long Switching the impact element was realized, can thus be omitted.

Fig. 1 als Schema, zeigend die Elektrohandwerkzeugmaschine

Fig. 2 als Blockschaltbild, zeigend die Steuerung;

Fig. 3 als Fliessschema, zeigend das Steuerverfahren,

Fig. 4a - 4f als Diagramme, zeigend die Steuerfunktionen

The invention will be explained in more detail with respect to an advantageous embodiment with:

Fig. 1 as a scheme, showing the electric hand tool

Fig. 2 is a block diagram showing the controller;

3 as a flow diagram, showing the control method,

Figs. 4a - 4f are diagrams showing the control functions

1, a partially rotating and beating electric hand tool 1 with a tool holder 2 for a tool an axially limited movable Impact element 3, which with respect to the tool holder 2 by only 0.5 mm axially is displaceable. On the workpiece side on a handle 4, this only partially covering, in Form a potentiometer switch, a pressure switch 5 to activate the connection of a Power source 6 in the form of the power supply network with a driving electric motor. 7 arranged. A for measuring a contact force F of the electric hand tool 1 against a workpiece suitable force sensor 8 is between the tool holder 2 and arranged the handle 4. Via an externally operable mode selector 9, the is connected to an electronic control unit 10 for the electric motor 7, the different operating modes I - V I of the electric hand tool 1 selectable the functions << Drill Chisels >>, << LowPowerDrilling >>, << Highspeed >>, << Meissein >>, << Chisels - TimeOut >>, << Chisels - Kickstart >> are assigned.

PM: Steuerparameter des Druckschalters 5

CF: Anpresskraftparameter des Kraftsensors 8

FS: Funktionsparameter des Modiwahlschalters 9

t: Zeit

2, in the circuit between the power source 6 and the electric motor 7, an electronic control unit 10 (including controller 11 / control 12 / power electronics 13) is arranged, which is controllably connected to the pressure switch 5, the force sensor 8 and the mode selector switch 9. The normalized control function OV = f (PM, CF, FS, t) stored in the memory of the control electronics 10 embodied as a microcontroller for controlling the control of the speed n of the electric motor 7 is a function f of the normalized control parameters PM, CF, FS, t with:

PM: Control parameters of the pressure switch 5

CF: Contact force parameters of the force sensor 8

FS: Function parameters of the mode selector switch 9

t: time

According to Fig. 3 is in the rotating and beating operating mode I << drill bits >> with the function parameter FS: I from the control electronics in a three-step Control method monitors in a first step of the control parameter PM, which is changes by pressing the discrete pressure switch. When operated by PM = 1, the intuitive control OV = max (CF, IS) activated. In a subsequent second step is with a control function OV, the speed control of the electric motor proportional to Contact force parameter CF controlled, but at least proportional to the normalized Idle parameter IS. After relief of the pressure switch by PM = 0 is in The third step is followed by the intuitive control and the entry point of the tax procedure for FS: I returned.

According to FIGS. 4a to 4f, the operating modes I-VI are for different functional parameters FS the control functions OV = f (PM, CF, t) are shown.

According to Fig. 4a in the operating mode I << drill bits >> the control is just as long activated, as the control parameter PM signals an actuation of the pressure switch. at activated intuitive control follows the control function OV regardless of the time t proportional to the contact force parameter CF, where a, the minimum speed of 50 rpm in Operating mode I << drill bits >> assigned idle parameters IS as lower Limit value is not fallen below. In a time domain Δt one of the force sensor measured, below a negative threshold negative force with CF <0 is the electric motor is controlled in proportion to the amount of this negative force.

According to Fig. 4b takes in the operating mode II << LowPowerDrilling >> in a time range .DELTA.t the Sensitivity of the control function OV by the contact force parameter CF progressive with the Activation period of the second step, where on, the minimum speed of 60 rpm in the operating mode << LowPowerDrilling >> not assigned lower limit is fallen short of.

According to FIG. 4c, in the purely rotating operating mode III << Highspeed >> in the second step is the Control function OV independent of the time t and the contact force parameter CF constant near an upper limit associated with a high speed of 1000 rpm.

According to FIG. 4d, in the purely beating operating mode IV << Meissein >> the activation / Deactivation of the intuitive control by the control function OV by one triggering operation of the control parameter PM with a click within 0.5 s, in which case the control function OV proportional to the contact force parameter CF, but at least to Idle parameter IS is.

According to Fig. 4e takes place in pure mode beating V << chisels - TimeOut >> Alternatively, the activation of the intuitive control by the control function OV by a triggering operation of the control parameter PM with a click within 0.5 s, the Deactivation, however, after falling below one, the blank space associated, lower Threshold value by the pressing force parameter CF over a time range Δt.

According to Fig. 4f takes place in the pure beating operating mode V I << chisel - Kickstart >> alternatively the activation independent of the control parameter PM by short-term Exceeding the contact force parameter CF, an activation force peak assigned, upper threshold within 0.5 s. The deactivation takes place after Falling below a, the blank space associated, lower threshold by the Contact force parameter CF over a time range Δt.

Claims (14)

Electric hand tool with an at least partially rotating driven tool holder (2) for a tool and a workpiece on a handle (4) arranged pressure switch (5) for activating the connection of a power source (6) with an electric motor (7), which with an electronic control unit (10 ), which is connected to a force sensor (8), characterized in that the force sensor (8) arranged between the tool holder (2) and the handle (4) and designed for measuring a contact force (F) of the electric hand tool against a workpiece is. Electric hand tool according to claim 1, characterized in that the pressure switch is designed as a discrete switch. Electric hand tool according to claim 1 or 2, characterized in that the control electronics (10) with a mode selector switch (9) is controllably connected. Electric hand tool according to one of claims 1 to 3, characterized in that an axially limited movable impact element (3) is present, which is axially displaceable with respect to the tool holder (2) by a maximum of 1 mm. Control method of an electric handheld power tool (1) with a first at least partially a tool holder (2) for a tool rotating operating mode (I), wherein in a first step by actuation of a workpiece on a handle (4) arranged pressure switch (5), the control is activated which in a second step controls an electric motor (7) as a function of a force measured by a force sensor (8), characterized in that the force is correlated with the contact force (F) of the electric hand tool (1) against the workpiece. Control method according to Claim 5, characterized in that, in the second step, the sensitivity of the control with respect to the force measured by the force sensor (8) is dependent on an activation period of the second step, optionally increasing progressively. Control method according to claim 5 or 6, characterized in that in the second step, the controller controls the electric motor (7) always above a minimum speed, which is optionally dependent on the operating mode (I, II). Control method according to one of claims 5 to 7, characterized in that in the second step in a negative force measured by the force sensor, the controller controls the electric motor depending on the amount of the negative force. Control method according to one of claims 5 to 8, characterized in that in a third step in discharge of the pressure switch (5), the control is deactivated. Control method according to one of Claims 5 to 9, characterized in that in the second operating mode (III) selected by the mode selector switch (9) in the second step, the electric motor (7) is controlled independently of the force measured by the force sensor (8). Control method according to one of claims 5 to 10, characterized in that in a non-rotating second operating mode (IV, V) in the first step, the activation of the control by a, in a trigger period of less than 0.5 s, triggering triggering / triggering of the pressure switch ( 5). Control method according to claim 11, characterized in that the control is deactivated by a triggering operation of the pressure switch (5) which is repeated alternately for the first step over a period of maximum 0.5 s. Control method according to one of claims 5 to 10, characterized in that the activation of the control in a non-rotating second operating mode (VI) in the first step, at a force peak measured by the force sensor (8) greater than an activation force, optionally within a trigger period of less than 0.5 s. Control method according to claim 13, characterized in that in the third step, the control is deactivated if over an idle period, the measured force is always less than a minimum force.

Images