EP1425770B1 - Regulating and control device for electric devices - Google Patents

Abstract

The invention relates to an electric switch (1), especially for an electric tool with an electric motor (2), e.g. an electric drilling machine, a hammer drill, an electric screwdriver or the like, comprising an actuating element (4) which can be adjusted between an initial and a final position. A set-point value device (6) actively cooperates with the actuating element (4) for the production of a set-point value associated with the adjustment path of the actuating element (4). The switch (1) also comprises a control device (8) for operating, especially for controlling and/or regulating, the electric motor (2) according to the set-point value. The adjustment path is divided into several sections, particularly into at least two sections, between the initial and final position in a step-like manner, each section being associated with a different digital code. The set-point value device (7) produces the digital code associated with the adjustment path of the actuating element (4) as a set-point value. The control device (8) subsequently processes the digital code so that the electric motor (2) can be operated accordingly.

Description

The invention relates to a setpoint device according to the preamble of patent claim 1.

In power tools, such as electric drills, rotary hammers, electric screwdrivers or the like, electrical switches are used to operate them.

From DE 197 08 939 A1 an electrical switch with a manually adjustable between an output and an end position actuator is known. The actuator is operatively connected to a potentiometer which emits a voltage corresponding to the adjustment of the actuator. The potentiometer thus serves as a setpoint device for generating an associated setpoint, which is represented in this case by the electrical voltage. This set value is supplied to a control device in the switch, wherein the control device operates, controls and / or regulates an electric motor as a function of this setpoint. For example, the control device sets the speed of the power tool according to the adjustment made by the user of the actuator.

The potentiometer in the switch consists of a slider and a resistance track, the slider by the operative connection with the actuator on the Resistance path slides. Usually, the resistor track is made by printing a resistor paste on a printed circuit board. The production of the resistance track is complex and sensitive to tolerances. The potentiometer is therefore an expensive component on the one hand and on the other hand, this can disadvantageously also lead to increased rejects.

Furthermore, GB 2 314 980 A has disclosed an electrical switch for a power tool, in which the resistance path for the potentiometer is replaced by individual discrete resistors. Apart from the consequent even higher costs due to the large number of resistors, which ultimately require an even more complex production of the setpoint device, the aforementioned problem of tolerance sensitivity is present here as well.

Finally, digitally operating setpoint devices are known, such as those for a gas or goods counter from GB 2 168 862 A and for a volume control in a radio from US Pat. No. 5,739,775 A. The setpoint device according to US Pat. No. 5,739,775 A has a rotor with grinders as contact elements, wherein a slider cooperate with a grounded contact ring and the other grinder according to the angular position of the rotor with contact segments for generating the digital code.

Furthermore, EP 0 570 870 A2 describes a digitally operating rotary selector switch in a domestic appliance. The rotary selector switch has light emitting diodes and photoreceptor and a turntable with a coding pattern, which has different optical properties in partial areas, so that a digital code is generated according to the position of the turntable.

However, there is no indication in such documents concerning these setpoint devices that such to use digitally operating setpoint device in a power tool.

The invention is based on the US 5,739,775 A the task of specifying a further use for the setpoint device. Furthermore, the electrical switch according to DE 197 08 939 A1 should be further developed in such a way that it is less sensitive to tolerances. In particular, it should be dispensed with the use of a resistance track and / or resistors in the setpoint device.

This object is achieved in a generic setpoint device by the characterizing features of claim 1 solved.

In the switch according to the invention, the adjustment path for the actuator between the initial and the end position is divided into several sections in the manner of stages, each of these sections is assigned a different digital code. The setpoint device is designed such that it generates the adjustment path of the actuator associated digital code as the setpoint. In the control device, this digital code is then processed for the corresponding operation of the electric motor. Since the digital code, in contrast to an analog resistance value is not subject to tolerances, the switch according to the invention does not have the disadvantages of the prior art. Further embodiments of the invention are the subject of the dependent claims.

The digital code generated by the setpoint device can be supplied directly and directly to the control device. A pre-processing or further processing in the setpoint device is not required, whereby the setpoint device according to the invention represents an overall cost-effective solution. With regard to the processing methods common in digital technology, it makes sense to use the number of sections as To choose power of two. In order to achieve a sufficiently large resolution of the setpoint device without much effort, it has proven to be convenient to divide the adjustment into eight sections.

The setpoint device can have a grinder and contact surfaces assigned to the respective section of the adjustment path. The grinder acts according to its Verstellweges then electrically contacting together with the respective contact surfaces, so that the respective digital code can be tapped from the electrically contacted contact surfaces in a simple manner. For this purpose, a contacted contact surface is expediently regarded as a logical "one" and a non-contacted contact surface as a logical "zero".

In a further embodiment, the switch has a housing. On the actuator a reaching into the housing ram is attached. Inside the housing, a lug for attaching the grinder is arranged on the plunger. The exterior of this switch is thus designed substantially in a conventional manner, so that the switch according to the invention can be used without further changes in the power tool instead of a conventional switch.

Conveniently, the contact surfaces are located on a circuit board. The contact surfaces may be in the form of printed conductors, in particular in a different arrangement and / or length, be configured, whereby the setpoint device can be realized in a small space. The circuit board is protected from harmful influences in the housing of the switch, in such a way that the grinder is movable on the contact surfaces along the adjustment path in the manner of a slider track. With regard to a compact design, it is further favorable to equip the grinder with a plurality of Schleiferfingem, wherein a respective Schleiferfinger cooperates with a contact surface.

Furthermore, it makes sense to also arrange the control device on the circuit board, which in turn contributes to the compact design of the switch. The control device can be used as electronic and / or electrical circuit for controlling and / or regulating the Be formed electric motor. The circuit for the control device is designed as an electronic digital and / or analog circuit. Preferably, the control device is a microprocessor and / or a microcontroller, in particular a single-chip microprocessor. The microprocessor and / or microcontroller is equipped for the purpose of good resolution with at least three inputs for the digital code, so that the adjustment path can be divided into at least eight sections. Since the microprocessor and / or microcontroller is also located on the circuit board, the inputs can be electrically connected directly to one contact surface, thereby saving space and costs. With the help of the microprocessor and / or microcontroller on the one hand, the feel of the switch is easily adaptable to the wishes of the user and on the other hand, additional functions of the control device can be realized without additional effort.

In particular, the control device is used to control and / or regulate the speed and / or the torque of the electric motor in functional dependence on the digital code generated by the setpoint device. The switch according to the invention then contains as a control device a pulse width modulation control for a DC voltage-driven electric motor or a phase control for a voltage-operated electric motor.

The digital code can be a binary or dual code. Preferably, this code is configured in one step. For example, it may be a Gray code, which advantageously has a particularly high level of error safety.

In addition, the setpoint device can not only be used in electrical switches, but can also be used independently. Such a setpoint device is in turn so operatively connected to an adjustable between an output and an end position actuator that a the adjustment of the actuator associated setpoint can be generated. The setpoint device has an electrical output for providing the setpoint. Again, the adjustment path between the initial and the end position in several Sections, in particular divided into at least two sections, in the manner of stages, each section being associated with a different digital code. The desired value of the adjustment path of the actuator associated digital code is generated and this provided at an existing electrical connections output. The setpoint device can of course also be provided with the described embodiments.

The advantages achieved by the invention are, in particular, that the large tolerances that conventionally occur when printing the resistance path and / or individual discrete resistors are not to be considered further. The control device, such as a conventional pulse width modulation circuit, has no more series variations of the duty cycle and the operating frequency. Nor do any fluctuations occur over the life of the switch. In addition, the life of the setpoint device is increased in comparison to the previously used potentiometer. The preparation of the setpoint device, in particular the printed circuit board used herein, is simplified. In addition, the proportion of the setpoint device on the circuit board requires less space, so that now additional functions that can only be realized very expensive due to the limited space in the switch, can be integrated into the switch according to the invention with little effort and largely without additional costs.

Fig. 1

ein Prinzipschaltbild für die Anordnung des elektrischen Schalters in einem Elektrowerkzeug,

Fig. 2

den elektrischen Schalter in Seitenansicht,

Fig. 3

einen Schnitt entlang der Linie 3-3 aus Fig. 2,

Fig. 4

eine schematische Draufsicht auf die im Schalter befindliche Leiterplatte,

Fig. 5

einen die Sollwerteinrichtung enthaltenden Teil des Schalters in perspektivischer Ansicht,

Fig. 6

die Sollwerteinrichtung in perspektivischer Ansicht und

Fig. 7

ein Diagramm zur Abhängigkeit zwischen Verstellweg des Betätigungsorgans und Drehzahl des Elektromotors.

An embodiment of the invention with various developments is shown in the drawings and will be described in more detail below. Show it

Fig. 1

a schematic diagram of the arrangement of the electrical switch in a power tool,

Fig. 2

the electrical switch in side view,

Fig. 3

a section along the line 3-3 of FIG. 2,

Fig. 4

a schematic plan view of the circuit board located in the switch,

Fig. 5

a part of the switch containing the setpoint device in a perspective view,

Fig. 6

the setpoint device in perspective view and

Fig. 7

a diagram of the dependence between adjustment of the actuator and speed of the electric motor.

The electrical switch 1 is used in an electrical device that is powered by a voltage source. Preferably, the electric switch 1 is used in a power tool such as an electric drill, a hammer drill, an electric screwdriver or the like. In Fig. 1, the schematic diagram for the arrangement of the electrical switch 1 in a power tool, which is powered by the AC line voltage U, shown in more detail.

The electric motor 2 has an electric motor 2 with field windings 3. The electric motor 2 is switched on and off by the user by actuation of the switch 1, which is located, for example, in the handle of the power tool, and its speed is adjusted by means of the switch 1. For this purpose, the switch 1 has a handle formed as an actuator 4, which serves as a handle for the user and is manually adjustable between an initial and an end position. When moving the actuator 4 is on the one hand in operative connection with a setpoint device 7 and acts on the other in certain positions switching to two contact systems 5, 6 a. The actual control and / or regulation for the operation of the electric motor 2 takes place by means of a control device 8 which is connected to a power semiconductor 9, such as a triac or the like. The control device 8 and the power semiconductor 9 operate in the manner of a phase control.

Due to the manual movement of the actuating member 4 from the initial position, the contact system 5 is first closed and the AC line voltage U is applied to the electric motor 2 via the power semiconductor 9. Next is the setpoint device 7 generates a desired value which is assigned to the adjustment path of the actuating member 4, starting from the starting position. This setpoint is then fed to the control device 8. The control device 8 ignites in functional dependence on the setpoint the power semiconductor 9 at the corresponding phase or Stromflußwinkel the AC line voltage U, so that finally set the position of the actuator 4 corresponding speed of the electric motor 2 and optionally regulated. The actuator 4 is in its end position, which corresponds to the maximum displacement starting from the starting position, the contact system 6 is closed, whereby the control device 8 and the power semiconductor 9 are bridged. Thus, the full mains AC voltage U is applied to the electric motor 2 and this moves with the maximum speed.

According to the invention, in the case of the electrical switch 1, the adjustment path between the starting position and the end position is divided into a plurality of sections, but at least two sections. In practice, the division into eight sections has proven to be useful. Each section is assigned a different digital code. The respective digital code is generated by the setpoint device 7 as a setpoint when the actuator 4 is moved in the corresponding section. This digital code is then processed by the control device 8 for the corresponding operation of the electric motor 2, wherein the electric motor 2 is driven as described so as to be operated with the functionally dependent on the setpoint speed. Since each section is associated with a digital code, these sections are formed in the manner of stages with respect to the corresponding speed. This step-shaped division of the sections can be seen in more detail in Fig. 7, in which the speed n of the electric motor 2 in connection with the displacement s of the actuator 4 is shown for a specific functional relationship between the setpoint and speed.

Below, the further embodiment of the switch 1 will now be described in more detail.

The switch 1 has to receive the electrical components, such as the contact systems 5, 6 u. Like., A housing 10, as more apparent from Fig. 2. On the actuator 4, a reaching into the housing 10 plunger 11 is attached. As in FIG. 3 can be seen, the setpoint device 7 has a grinder 12 and contact surfaces 15 on the grinder 12 is attached to a arranged in the interior of the housing 10 on the plunger 11 approach 13. The contact surfaces 15 are located on a printed circuit board 14. The printed circuit board 14 is arranged in the housing 10, that the grinder 12 can interact with the contact surfaces 15, which can be seen in particular in the perspective view of FIG. As can further be seen in the enlarged illustration according to FIG. 6, the wiper 12 now interacts electrically with the contact surfaces 15 assigned to the respective section of the adjustment path, so that the digital code can be tapped from the electrically contacted contact surfaces 15. The digital code is then fed directly and directly from the setpoint device 7 to the control device 8.

As can be seen with reference to FIG. 6, the contact surfaces 15, in particular in the form of conductor tracks, are formed on the printed circuit board 14. In this case, the contact surfaces 15 consist of side by side differently arranged and a different length owning individual contact surfaces 15a, 15b, 15c, 15d, as can be seen clearly in Fig. 4. The contact surfaces 15a, 15b, 15c, 15d are provided with electrical connections 16, which serve as an output for the setpoint device 7. With the electrical terminals 16 of the output of the setpoint device 7 is then the corresponding input of the control device 8 in electrical connection.

The grinder 12 is movable on the contact surfaces 15 along the adjustment path in the manner of a slider track. The grinder 12 has a plurality of wiper fingers 12a, 12b, 12c, 12d, so that in each case one wiper finger 12a, 12b, 12c, 12d interacts with one contact surface 15a, 15b, 15c, 15d. Depending on the adjustment of the four-element grinder 12 according to the position of the actuator 4, the slider 12 bridges with the aid of its wiper fingers 12a, 12b, 12c, 12d, the contact surface 15d with one or more of the contact surfaces 15a, 15b, 15c, whereby at these contact surfaces 15a, 15b , 15c either because of the contacting the same electrical potential as at the contact surface 15d or due to the non-contacting a different electrical potential is applied.

Expediently, the contact surfaces 15a, 15b, 15c are connected to a voltage, for example 5 volts, and the contact surface 15d is grounded. When bridged by the wiper fingers 12a, 12b, 12c, the corresponding contact surface 15a, 15b, 15c is then also pulled to ground. The respective electrical potential at the contact surfaces 15a, 15b, 15c thus represents a binary state according to a logical "0" or "1" (bit), so that the digital code corresponding to the adjustment path of the grinder 12 by a binary or dual code is represented, as illustrated in particular with reference to FIG. 4.

By means of the three contact surfaces 15a, 15b, 15c shown in FIG. 4, which correspond in each case to one digit of the digital code, eight (equal to 2 high 3 bit) states in binary / dual-code can thus be distinguished as a power of two, as a result of which the signals shown in FIG. 7 shown eight sections of Verstellweges the binary / dual code are clearly assignable. Of course, depending on the need for sections for the adjustment also a different number of contact surfaces 15 can be selected. According to the arrangement of the contact surfaces 15a, 15b, 15c, this binary / dual-code can be configured in one step, so that the digital code changes in two consecutive sections only in one bit. For example, the binary / dual code may be a Gray code, a 3-bit Gray code according to the three pads 15a, 15b, 15c. The Gray code advantageously has a high level of fail-safety and can be realized extremely space-saving with the four contact surfaces 15a, 15b, 15c, 15d on the printed circuit board 14.

The control device 8 is also located on the circuit board 14 in the housing 10. The control device 8 is designed as an electronic and / or electrical circuit, preferably in the manner of a chip, as shown in FIG. 3. The control device 8 may be an electronic digital and / or analog circuit for controlling and / or regulating the electric motor 2. In particular, a microprocessor / microcontroller is suitable as a control device 8, which may expediently be a single-chip microprocessor equipped with at least three inputs for the digital code corresponding to the electrical connections 16 on the contact surfaces 15a, 15b, 15c.

As stated, the control device 8 can control and / or regulate the rotational speed of the electric motor 2 in functional dependence on the digital code generated by the nominal value device 7. In Fig. 7 is an example of a curved and disproportionately running at higher speeds characteristic shown. Of course, another characteristic can be selected, for example, with a substantially linear dependence between displacement s and speed n. It should be emphasized that when using a microprocessor / microcontroller, the assignment between the digital code and the speed by programming in a simple manner can be specified so that advantageously allows an individual and simple adjustment and the feel of the switch 1 is adjustable in the user's desired sense. Of course, the torque of the electric motor 2 can be controlled and / or regulated alternatively or in addition to the rotational speed according to the digital code, which may be desirable, for example, in an electric screwdriver.

The invention is not limited to the described and illustrated embodiment. Rather, it also encompasses all expert developments within the scope of the invention defined by the claims. Thus, such a switch can be used not only on an AC power operated power tool but also on a powered with DC battery tool. In this case, as a power semiconductor 9, a FET, MOS-FET o. The like. Used and the controller 8 operates by means of a pulse width modulation. By appropriate assignment of the digital code to the frequency and / or the duty cycle of the pulse width modulation, the desired functional dependence of the rotational speed of the adjustment path is also set here. Furthermore, such a switch can also be used in other electrical devices supplied by a voltage source, such as gardening tools, kitchen appliances or the like. Finally, the setpoint device according to the invention can also be used independently, for example as a replacement for a potentiometer.

Reference numeral list:

1:

electrical switch

2:

electric motor

3:

field winding

4:

actuator

5,6:

Contact system

7:

Set value unit

8th:

control device

9:

Power semiconductor

10:

casing

11:

tappet

12:

grinder

12a-d:

wiper finger

13:

Approach (on the ram)

14:

circuit board

15

(A-d):

contact area

16:

electrical connection

Claims (10)

1. Electric device with a set-point value mechanism (7), wherein an actuating element (4), which can be adjusted between an initial position and an end position is in operative connection with the set-point value mechanism (7) in such a way that a set-point value allocated to the adjustment path of the actuating element (4) can be generated, the adjustment path between the initial and the end position being divided into a plurality of sections, in particular into at least two sections, in the manner of steps, a different digital code being allocated to each section, and wherein the digital code allocated to the adjustment path of the actuating member (4) is generated, as the set-point value, and wherein the set-point value mechanism (7) has an electric output consisting of electric terminals (16), at which output the set-point value is provided as a digital code, characterised in that the electric device is an electric tool with an electric motor (2), such as an electric drill, a hammer drill, an electric screw driver or the like, in that the electric tool has a control mechanism (8) for operating the electric motor (2) according to a characteristic curve as a function of the set-point value, and in that the control mechanism (8) processes the digital code for corresponding operation of the electric motor (2), in that the control mechanism (8) controls and/or regulates the speed and/or the torque of the electric motor (2) in functional dependency, corresponding to the characteristic curve, on the digital code generated by the set-point value mechanism (7).
2. Electric device according to claim 1, characterised in that the set-point value mechanism (7) is arranged in an electric switch (1).
3. Electric device according to claim 2, characterised in that the adjustment path is divided into eight sections, and in that the digital code from the set-point value mechanism (7) is preferably supplied indirectly and directly to the control mechanism (8).
4. Electric device according to claim 2 or 3, characterised in that the set-point value mechanism (7) has a slider (12), and in that the slider (12) preferably cooperates in an electrically contacting manner with contact faces (15), which are allocated to the respective section of the adjustment path, in such a way that the respective digital code can be picked up by the contact faces (15), in particular as a function of their electrical contacting and non-contacting in the manner of a logic "1" or "0".
5. Electric device according to claim 2, 3 or 4, characterised in that the switch (1) has a housing (10), in that a plunger (11) reaching into the housing (10) is preferably fastened to the actuating element (4) and in that a shoulder (13) for fastening the slider (12) is more preferably arranged in the interior of the housing (10) at the plunger (11) .
6. Electric device according to any one of claims 2 to 5, characterised in that the contact faces (15) are located on a printed-circuit board (14), in that the contact faces (15) are preferably configured in the manner of conductors, in particular, in a different arrangement and/or length, in that the printed-circuit board (14) is more preferably arranged in the housing (10) in such a way that the slider (12) can be moved on the contact faces (15) along the displacement path in the manner of a slider path, and in that still more preferably, the slider (12) has a plurality of slider fingers (12a, 12b, 12c, 12d), one slider finger (12a, 12b, 12c, 12d) cooperating in each case with a contact face (15a, 15b, 15c, 15d).
7. Electric device according to any one of claims 2 to 6, characterised in that the control mechanism (8) is configured as an electronic and/or electric circuit for controlling and/or regulating the electric motor (2), in that the control mechanism (8) is preferably configured as an electronic digital and/or analogue circuit, and in that the control mechanism (8) is more preferably located on the printed-circuit board (14).
8. Electric device according to any one of claims 2 to 7, characterised in that the control mechanism (8) is a microprocessor and/or a microcontroller, in particular a single-chip microprocessor, with at least three inputs for the digital code, and in that the inputs of the control mechanism (8) are preferably electrically connected, in particular at an electric terminal (16), to a contact face (15a, 15b, 15c) in each case.
9. Electric device according to any one of claims 2 to 8, characterised in that the control mechanism (8) contains a pulse width modulation control for an electric motor (2) operated by direct voltage or a phase-fired control for an electric motor (2) operated with alternating voltage.
10. Electric device according to any one of claims 2 to 9, characterised in that the digital code is a binary or dual code, which is, in particular cyclic, for example a Gray code.

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