DE19945286A1 - Controller for commutator motor for electric hand tools , divides direct voltage into first and second ranges with fixed sectional height in second range during operation of motor without changeover processes - Google Patents

Abstract

The controller has first and second control devices (4,5) associated with a pulse width modulator (3) for first and second frequency sections of a direct voltage. The direct voltage is divided into first and second sections with a fixed D.C. level in the second sections during the operation of the motor (1) without changeover processes and for a smooth transition from steady to increasing rotary characteristic.

Description

The invention relates to a control according to the Ober concept of claim 1.

Commutator motors are by assigning electronics variable speed control. Such an electric nik can, for example, include a leading edge control AC operation or a pulse width modulator Include DC operation. Such controllable Stromwen dermotoren also come in handy with electric hand tools to use.

There are use cases for electrical hand tools, for example wise in the case of forceful screwing work and safe drilling in sheet metal and aluminum, where it is an advantage if the power tool is equipped with electronics, with which a rising and falling torque or a pulsed maximum speed can be achieved with a commutator motor.

Such electronics are known from DE 195 01 430 A1. There, a method for controlling an electric motor is described which is used in power tools. The electric motor ( 1 ) is subjected to changeable pulses ( 11 , 11 ', 20 ) of an electrical voltage (U) in such a way that the rotor of the electric motor moves at an adjustable speed (n 1, n 2). Phase angle controls or pulse width modulators are used for this. The jerky or jerky movement of the rotor of the electric motor ( 1 ) is achieved in that parts of individual pulses ( 11 , 11 ', 20 ) are masked out by superimposing a pulse pause ( 12 , 12 ', 22 ) with a zero voltage.

Furthermore, a circuit arrangement in DE 195 is 01 430 A1 for driving an electric motor (1) having control electronics (5) and an electronic power scarf ter (4), wherein the switches of the electronic power (4) by the control electronics (5) in such a way is switched that via the electronic circuit breaker ( 4 ) changeable pulses ( 11 , 11 ', 20 ) of an electrical voltage (U) to the electric motor ( 1 ) for operating the electric motor at a preset speed (n 1, n 2) can be created. The jerky or jerky movement of the rotor of the electromotor ( 1 ) is achieved here in that the control electronics ( 5 ) have means for switching off the electronic power switch ( 4 ) during at least parts of the fewest individual pulses ( 11 , 11 ', 20th ) contains.

The disadvantage of such an actuation of an electric motor is that, for example, in a phase control control a constant number of half-waves each AC voltage can be completely hidden. This measure is particularly at a low speed, i.e. at large cut of the remaining half-waves, disturbing because at a low speed during a screwing process ne continuous speed is more advantageous.

Electronics is known from EP 0 784 884 B1, with which a jerky rotational speed can also be set. Here, an electric screwing tool is provided with a universal motor (1) be written, the (3) variable for determining speeds is operated by means of a phase control, whereby the Pha senanschnittsteuerung (3) to a wave packet controlled Pha senanschnittsteuerung is switchable. In the case of the phase-angle control controlled by wave packets, not all half-waves of the network are also controlled. The control and not control of the half-waves is achieved with an oscillator ( 4 ) which can be switched on to the phase control. The further the frequency of the oscillator ( 4 ) lies below the network frequency of 50 Hz, the fewer half-waves of the network are controlled.

The operation of this control corresponds to that of DE 195 01 430 A1, and therefore the disadvantage is the same.

The published patent application DE 196 09 986 A1 describes a process for operating an electric motor in which electronics are used, with which a first, a second and a third speed can be achieved. When the electric motor is operated in alternating current, the electronics consist of a leading edge control and the electric motor is used for electric screwdriving tools. At the first pre-set speed, the screw is screwed in until the screw head comes close to the material surface, first phase of operation. If the previously set limit torque is reached, the electric motor is switched over in a further operating phase via the electronics, and the motor is now controlled in such a way that a periodically interrupted so-called after-torque is exerted by the electric motor through torque breaks of a certain length. In the second operating phase, the electronic switch is periodically switched on again, and the pauses for switching on again can be up to one second, column 7 , lines 5 to 10 .

On the one hand, this is a method in which a phase control can be switched to a wave packet control, column 5 , lines 30 to 51 , similar to the method from EP 0 784 884 B1.

On the other hand, it is disclosed in this document that the second Speed corresponds to a minimum current flow angle, column 6, Lines 53 to 56, column 7, lines 52 to 56.

From the description and drawing of this document goes shows that the electronics of the phase control min at least two or three operating states for an electric Tool causes, the first and the second or the third operating state on the amount of power consumption of the Electric motor is dependent. If the previously set  The current consumption threshold is exceeded Electronics from the first operating state in which the Elektromo Power tool gate with variable adjustable continu ore constant speeds is operable in the second and third operating state in which the electric motor has a more or less jerky turning behavior.

The method according to DE 196 09 986 A1 with up to three Operating states during a screwdriving process with a Power tools have the disadvantages that the transition from one continuous, steady turning behavior of the electric motor a jerky turning behavior not sliding but abrupt takes place, and the jerky turning behavior is not controllable.

US Pat. No. 5,731,673 shows the same method as in DE 196 09 986 A1. Fig. 4 shows also a first operating condition 54, a second operation state 60 and ei NEN third operating state 62. The switchover from the first operating state to the second and to the third operating state takes place in exactly the same way as in DE 196 09 986 A1 when the predetermined current threshold 56 is exceeded.

The disadvantages are the same as in DE 196 09 986 A1.

DE 35 34 052 A1 describes a method for generating a Overload alarms when operating a power tool, the a clear, unmistakable hint to the user the overload condition there. The method described be in the event of an overload condition, a reduction in the Power tool input power, reducing the speed of the electric motor is reduced, and then takes place in addition a cyclical raising and lowering of the reduced th supplied power, whereby the speed of the electromotive with the output reduced, the oscillates until the Overload condition has ended. For speed control is that Power tool a microcontroller controlled phases cut control assigned.  

The procedure described here takes place for screwdriving and drilling work with a power tool no application since one Lowering the reduced feed reciprocating Performance is unsuitable for such applications.

WO 99/27643 discloses a control system with a power inverter mo gate, which is only designed for the AC motor. It will in this document pointed out that in Equal Power operation of the commutator motor basically the same Control is used, but as with direct current the function of such a control should take place, does not appear from this script.

The invention has for its object a controller for to create a commutator motor, making a sliding smooth transition from a steady turning behavior of the motor to a with a continuously increasing torque correspondingly reinforcing, jerky turn behavior of the motor is achieved in DC operation.

This task is characterized by the characteristics of the independent contractor spell 1 solved. Advantageous design features of the Er are to the rest of the claims and the description remove.

The advantage of the control according to the invention for a stream Wendermotor is that the pulse width modulator control facilities are assigned, with which a first section the DC voltage into first area sections and a second section of the DC voltage in the second Be empire sections is feasible with the purpose that at egg a small speed and a small torque a steady rotation behavior of the motor and continuously on increasing torque proportional to the torque a gentler Transition to an increasingly jerky turning behavior  of the motor is achieved, such a turning behavior of the motor advantageously takes place without switching operations.

This turning behavior of the motor is particularly important with Schraubar advantageous with a power tool.

The invention is based on the drawing he he purifies.

Show:

Fig. 1 shows a circuit arrangement of the electronic Steue tion for a commutator motor,

Fig. 2 is a representation voltage of a DC voltage with un terschiedlichen extracts the DC chip,

Fig. 3 is an illustration of a direct current voltage with egg nem frequented first section of the DC voltage in the first range sections with a second traffic segment of the DC voltage in the second area portions,

Fig. 4 is a graphical representation of the motor current with respect to the embodiment of Fig. 3,

Fig. 5 is an illustration with a variably adjustable frequented section of the DC voltage in the first range sections and with a varia problem cutting out the DC voltage into two portions th region,

Fig. 6 is an illustration with a variably adjustable frequented section of the DC voltage from the minimum section up to the maximum section of the DC voltage in repeating area sections of a DC voltage.

Electric hand tools are mostly with electronics equipped for speed control by using AC operated a phase control and with DC driven a pulse width modulator is used. The twist Payment control electronics of the power tool can be for agreed to use additional controls to achieve the application a rising and falling torque of the electric be assigned to the tool motor. The turn is corresponding Number control electronics designed so that the Stromwen the motor of the power tool with both variable steady Speed, as well as variable, impulsive jerky Speed is operable.

Fig. 1 shows a circuit arrangement of such a control tion. In series with the commutator motor 1 is a Transi stor 2 , to which a pulse width modulator 3 is assigned. The pulse width modulator 3 can be operated via a first, a second and a third control device 4 , 5 , 6 . With which he most control device 4 of the pulse width modulator is operated in known manner be, and the DC voltage is frequency-like excisable in its entirety by the first control device. 4 The first control device can include an adjustable resistor and can be designed as a rotary potentiometer or as a slide potentiometer, the slide potentiometer preferably being arranged in a power switch and being operated with the operating element of the power switch.

Fig. 2 shows a standard variable frequented section a, b, c, d of a DC voltage, which is aimed at using a pulse width modulator 3 designed in a known manner.

To achieve a pulsed jerky speed in a commutator motor 1 , the pulse width modulator 3 is assigned a first and second control device 4 , 5 . With the second control device 5 , which can also include an adjustable resistor or a tap changer, corresponding area sections of a direct current voltage can be influenced, whereby first and second area sections of a direct current voltage are formed.

Fig. 3 shows such sections of a DC voltage. In first area sections 7 there is a first frequented section a ', b', c ', d' of the direct current voltage and in second area sections 8 a second frequented section e, the first and second area sections 7 to achieve jerky rotation of the commutator motor, 8 keep repeating. The fre quent section of the DC voltage in the second range sections 8 is variably fixed with the second control device 5 , and with a third Steuerein device 6 , the second range sections 8 are set in their width and in their repetition frequency.

In the case of a standard frequented section of the direct current voltage, the second frequented section e of the direct current voltage is set to a minimal section with the second control device 5 or this section is completely canceled, as a result of which, in a known manner, a variable frequented section of the direct current voltage with the first control device 4 , is achieved according to the FIG. 2.

With a first and a second frequented section of the DC voltage there are always first and second loading sections 7 , 8 of cut DC voltage, the frequented section of the DC voltage of the second section 8 being adjustable independently of the first section 7 , and with the fre Quentted section of the DC voltage of the first loading area sections 7 , the electric motor can be operated independently of the second area sections 8 .

If a more or less swelling and decelerating torque and thus a jerky turning behavior are to be achieved with a current converting motor, the second control device 5 is used to set the second frequented section e of the direct current voltage accordingly. This second frequented section of the direct current voltage in the second area sections 8 can be set independently of the first frequented section of the direct current voltage in the first area sections 7 . If the permanently set second frequented section is smaller than the first frequented section, the total DC voltage is cut out via the first control device 4 up to the permanently set section height 9 of the second frequented section, and in the further course of the section reduction of the direct current voltage to the minimum or no frequented section, the direct current voltage is cut out only in the first area sections 7 via the first control device 4 , the section height 9 of the direct current voltage which is fixed with the second control device 5 remaining constant in the second area sections 8 .

The variably fixed section height 9 of the second section of the DC voltage in the second area sections 8 can also characterize the area of a set limit torque in which, depending on the torque of the commutator motor, the frequented section of the DC voltage in the second area sections 8 is proportional to the increasing torque of the motor increases beyond the set limit torque, so that an increasing jerky rotational behavior of the commutator motor is achieved as a function of the torque. The torque can be seen in relation to the amount of current drawn by the motor.

For screwing in large screws with a power tool, a lower fixed cut-off height 9 of the DC voltage in the second loading area sections 8 is preferably set as for small screws, so that a continuous, steady speed is achieved at the beginning and in the further course of the screwing process, and for At the end of the screwing process there is a more or less jerky speed without switching operations being required. Thus, in a single operating state, both a steady and a jerky rotational behavior that increases in proportion to the torque can be achieved in an electric motor.

The first and second sections described here in first and second area sections of a DC voltage are explained in more detail with the aid of a diagram. Fig. 4 shows a diagram of the current profile during motor operation with a steady and with a more or less jerky turning behavior of the commutator motor. The DC voltage is divided by the speed control electronics of the commutator motor into a corresponding grid, consisting of first and second area sections 7 , 8 of DC voltage. With the first direction Steuerein 4, the DC voltage is up to the level set by the second control means 5 Ausschnittshö he 9 of the DC voltage in the second Bereichsabschnit th cut frequented. 8 The current curve 10 characterizes the continuously increasing current profile during a screwing operation with a steady rotation behavior of the commutator motor up to the variably adjustable section height 9 of the DC voltage in the second loading area sections 8 . Thereafter, a theoretical current curve 10 'continues in dashed lines. In the further course of the screwing process, the torque required for this and thus also the current consumption of the commutator motor increases, with a current consumption of the commutator motor beyond the fixedly adjustable section height 9 of the direct current voltage in the second region sections 8 and the current in the second region sections 8 remaining approximately constant , and in the first area sections 7 , the current increases proportionally to the theoretical current curve 10 '. If the current in the first area sections 7 exceeds the current in the second area sections 8 , the rotational speed of the commutator motor in the second area sections 8 drops accordingly, whereby a correspondingly increased increase in the current in the first area sections 7 is caused.

With the solution outlined here, a sliding becomes smoother Transition from variable steady turning behavior to jerky Rotational behavior of the commutator motor achieved.

According to FIG. 3, both a continuous and a smooth rotational behavior at a Elek tromotor achieved by different frequented cut off, the DC voltage to first and second loading rich portions of a DC voltage at a single operating condition. This Drehver hold a commutator motor can also be achieved by variable fre quentten cut out of the DC voltage in first loading area sections and by hiding DC voltage in second section sections.

Fig. 5 shows such a solution. A variable, frequent cut-out of the DC voltage with the first control device 4 of the pulse width modulator takes place in the first area sections 7 'in a known manner. The first area sections 7 'of FIG. 5 only show the same gate. In the second area sections 8 ', DC voltage is masked out with the second control device 5 , since the width of the second area sections 8 ' can be variably adjusted with the second control device. The suppression of the DC voltage begins with a minimum width of the second area sections 8 '. The width of the first and second area sections 7 '; 8 'each comprises an overall area section 11 . The width of the total area section 11 of a DC voltage can advantageously be the same in each case, and the total area section repeats itself continuously, thus the first and second area sections 7 '; 8 'in its Wei te with the second control device 5 so variable that a greater setting of the width of the second area section 8 ', the width of the first loading area section 7 'decreases by the same value. The width of the total area section 11 can also be set differently.

The variable traffic section of the DC voltage to the first region portions 7 'and the hiding of DC voltage in the second area portions 8' can take place with the aid of a microcontroller, wherein the adjustment of the length of the second section parts can be 'coupled 8 at the torque of the commutator motor. The setting of the torque to suppress DC voltage in the second section 8 'is also determined with the second control device 5 . The microcontroller is programmed so that when the set torque is reached, the blanking of the DC voltage begins with a minimum width of the second area section, and with increasing torque the blanking of the DC voltage in the second area sections 8 ', the width of these area sections is proportional to the rise The increasing torque increases, so that with increasing torque there is an increasing jerky rotational behavior of the commutator motor. The width of the first section sections 7 'can also be kept constant by increasing the total section sections by the width of the second loading section section 8 '.

Fig. 6 shows a further solution with which a steady and jerky turning behavior is achieved in a commutator motor. With the second control device 5 , the pulse width modulator can be influenced here so that in section sections of a DC voltage, with periodic repetition of these section sections, the section of the DC voltage from the minimum section linearly or not linearly up to the maximum section takes place, this process can be coupled to the torque of the commutator motor. This course of the frequented section of the direct current voltage in the area sections 12 is recorded in the first representation f of FIG. 6. The start of the frequented section of the direct current voltage can be variably determined with the first control device ( 4 ). The variably adjustable start of the frequented section of the direct current voltage characterizes the area sections 12 'of the first representation f of FIG. 6. The direct current voltage in the section sections with the minimum frequented section and the direct current voltage with a maximum frequented section is corresponding determinable. The second representation g of FIG. 6 shows such sections 14 , 14 ', 15 , the beginning of the frequented section of the direct current voltage being adjustable here with the first control device 4 in a variable manner.

One control for a commutator motor, in which several Control devices for operating a speed control device are used, with which an impulse-like Speed is achieved, comes advantageously with electric screw and electric drilling tools for use.

A pulse-like speed in power tools is below other with comfortable drilling in all materials without to be particularly well suited without the boh  rer runs, and such a rotational behavior of the drill allows convenient and safe drilling in sheet metal and aluminum nium. A pulse-like speed is also advantageous applicable for forceful screwing work, especially for screws that are difficult to screw in or difficult to loosen.

The invention is not described and illustrated on the limited embodiments, but it can do a lot sided with electronically controllable commutator motors for Come into play.

Claims (8)

1. Control with a commutator motor ( 1 ), which is operated by means of a pulse width modulator ( 3 ) with a steady as well as with a jerky turning behavior, for which purpose the pulse width modulator ( 3 ) a first and a second control device ( 4 , 5 ) for a first and a second frequented section (a ', b', c ', d'; e) is assigned to a direct current voltage, characterized in that
that during the operation of the commutator motor ( 1 ) without switching operations and with a smooth transition from steady to jerky rotational behavior, both a steady and a jerky rotational behavior of the commutator motor ( 1 ) is achieved by a grid-like constant division of the direct current voltage into first and second area sections ( 7 , 8 ) with a fixed cutout height ( 9 ) of the direct current voltage in the second area sections ( 8 ),
that with the first control device ( 4 ) the DC voltage can be cut out with variable frequency, and with the second control device ( 5 ) the frequent cut from the DC voltage in the second range sections ( 8 ) is adjustable, the frequented cut from the DC voltage the first Steuereinrich device ( 4 ) in the first and in the second section sections ( 7 , 8 ) from the maximum frequented section up to the fixed section height ( 9 ) of the DC voltage in the second section sections ( 8 ), and in the further course of the Cutout of the DC voltage down to the minimum cutout, the DC voltage is cut out only in the first area sections ( 7 ) with the first control device ( 4 ), the cutout height ( 9 ) of the DC voltage in which is fixed with the second control device ( 5 ) the second area sections ( 8 ) remains constant. 2. Control according to claim 1, characterized in that with the first control device ( 4 ) of the first variable frequented section (a ', b', c ', d') of the DC voltage in the first area sections ( 7 ) independently of the second frequented Section (e) of the DC voltage in the second area sections ( 8 ) can be carried out, and with the second control device ( 5 ) the section height ( 9 ) of the second frequented section (e) of the DC voltage can be set independently of the first control device ( 4 ) . 3. Control according to claim 1 and 2, characterized in that the adjustable section height ( 9 ) of the second frequented section of the DC voltage in the second section sections ( 8 ) indicates the range of a set limit torque, in which depending on the torque of the commutator motor ( 1 ) the frequented section of the DC voltage in the two th area sections ( 8 ) increases proportionally to the increasing torque of the motor beyond the set limit torque. 4. Control according to claim 1 to 3, characterized in that the second frequented section (s) of the DC voltage with the second control device ( 5 ) is variable from a little or no fre quent section to the maximum frequented section, and with a third control device ( 6 ) the width of the second area sections ( 8 ) and thus the repetition frequency of these area sections ( 8 ) is adjustable. 5. Control according to claim 1, characterized in that during the operation of the current inverter motor ( 1 ) without switching operations, both a steady and a jerky rotational behavior of the commutator motor ( 1 ) is achieved by variable frequent cutting of the DC voltage with a first control device ( 4 ) in first area sections ( 7 ') and by continuously hiding DC voltage in second area sections ( 8 ') with a second control device ( 5 ), the hiding of the DC voltage in the second area sections being coupled to the torque of the commutator motor ( 1 ), in that when the torque set by the second control device ( 5 ) is reached, the specified DC voltage is masked out, and with an increasing torque, the masking of the DC voltage in the second region sections ( 8 ') increases in proportion to the increasing torque. 6. Control according to claim 5, characterized in that the width of the first and the width of the second area section ( 7 '; 8 ') each form a total area section ( 11 ), and this overall area section is repeated continuously, the width of the Total area sections is always the same, or increases by the increasing value of the second area section 8 '. 7. Control according to claim 1, characterized in that with a first Steuereinrich device ( 4 ) in a first section of a DC voltage variable speeds can be achieved, and with a second control device ( 5 ) the pulse width modulator ( 3 ) can be influenced so that within from consecutive second area sections ( 12 ) of a direct current voltage, the frequented section of the direct current voltage in the second section sections ( 12 ) increases linearly or non-linearly up to the maximum frequented section, where at the beginning of the height of the frequented section ( 12 ') of the direct current voltage in the second area sections ( 12 ) with the first control device ( 4 ). 8. Control according to claim 7, characterized in that the DC voltage with a minimum and a maximum frequented section in the second area sections ( 12 ) can be determined, and the beginning of a periodic repetition of the increasing section of the frequented section up to the maximum frequency sectioned is coupled to the torque of the commutator motor in the second section sections ( 12 ).