DE3101411A1 - Circuit arrangement for an electrical hammer apparatus - Google Patents

Abstract

The invention relates to an electronic circuit for an electrical hammer apparatus, for brackets, nails or the like. It is designed such that the hand switch is connected in the circuit of the hammer magnet and is switched in a current-free manner. <IMAGE>

Description

30 039-19

3.1014 II

IIAUCK. SCHMITZ- · CJRAAIjFS 'WEI INERT ■ CARSTINS. DOERING

HAMBUKG MÜNCHKN DUvSSRIJ) OHP PATKNTANWAl.TE · NISURH WALL · 41 ■ 2001) HAMBURG 30 Dipl.-Phys. W. SCHMITZ - IJlpl.-lnjv. IC. CIUAl.FS

New WuIl 41 · HOOO [Inmliurj; HCt ΤηΙοΓοη + Telecopier (CMO) '.Ui O7 55 Telex O2117CS1) input <i

Dlpl.-Iiifi. II. IIAUC'K - Dipl.-Infj. W.WHI INIiHT

ESCO METALLWAREN nipi.-Ph.vs. vv. cahsthns

Martin HÜhnken Mossnrisirnßo 23 · HOCK) Munich 2

Telephone + Telceopier (OH!)) 53OSi) CJ

Rudolf-Diesel-Str. 7 Telex 05sinssapmnu <i

2072 Barateheide Dr.-inj.:.\v. döhinc;

^y . K.-Wilhelm-HinjL · 41 · 4000 HÜBsoldorf H

Telephone (O2II) 575O 27 / 2H ZUSTIiI-LUNGSANSCIIHIFTZHLIaASBHlOPLYTO: HAMBUHG, ^ 6 January 1981

Circuit arrangement for an electrical driving device

The invention relates to a circuit arrangement for an electric driving tool for driving nails, staples or the like with one over one Circuit breaker connected to the AC voltage magnet coil, a control stage connected to the AC voltage source, which when a pushbutton switch is actuated generates a switch-on pulse for the circuit breaker.

The basic structure of an electric driving tool has been known for a long time (DE-PS 1 478 899). The • driving ram for the nails or staples is part of one

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j ferromagnetic plunger or is ge

that is drawn into a solenoid,

ί when this is connected to the voltage source. One

j Return spring ensures the return of the drive

plunger into the rest position when the magnetic coil has been switched off.

It is also known to control the solenoid with the aid of a power thyristor. Of the The power thyristor is connected to AC voltage in series with the magnetic coil. With the help of a pulse circuit The control electrode of the power thyristor is controlled and ignited via another thyristor, when the push button of the driving device is pressed (DE-OS 2 238 440).

In the known circuit arrangement, the control circuit for the power thyristor is constantly connected to the AC voltage source. There is therefore the risk of a switch-on pulse due to a short circuit or similar interference is generated even though the pushbutton switch is not actuated at all. However, this phenomenon is extreme in terms of security detrimental as a failure can both injure an operator and damage objects.

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The invention is therefore based on the object of a circuit arrangement for an electrical driving device for hammering nails, staples or the like to be created by the circuit arrangement itself caused failures can be avoided with certainty.

This object is achieved according to the invention in that the push-button switch is connected in series with the circuit breaker and the solenoid, the control stage is constantly connected to the AC voltage source, a first locking stage connected to the control stage suppresses the generation of a switch-on pulse, as long as the pushbutton switch is open and the control stage is only released when the pushbutton switch is closed a full half-wave is pending, and a second locking stage connected to the control stage Generation of a switch-on pulse suppressed after a first switch-on pulse has been generated.

In the circuit arrangement according to the invention, there is the pushbutton switch with which a blow of the driving device is located is triggered, with the circuit breaker and the coil in series. As long as the pushbutton switch remains open, will the control stage is locked and therefore cannot generate a switch-on pulse. The lock is only

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ended when the pushbutton switch has been actuated. So now a full half-wave to generate the impact force is used, only the half-wave following the closing of the pushbutton switch, for example the positive one Half-wave, applied to the solenoid coil by opening the circuit breaker. The second locking stage 'provides that only a single switch-on pulse is generated, so that the driving tool only blows a single blow is performed and another blow can only occur after the open pushbutton switch is actuated again.

The first level of locking

ensures # that the pushbutton switch is de-energized. This is of some importance as a current of considerable strength flows through the magnetic coil when it is switched on Tension is laid. '

The circuit arrangement according to the invention ensures that Failures when the pushbutton switch is not actuated can be avoided with great certainty. ·

An embodiment of the invention provides ^: that the first locking stage has a Thy-

3 1 01 A

contains ristor, the control circuit is also constantly connected to the AC voltage source, and the Control circuit is short-circuited via a transistor, the base of which is voltage-free when the pushbutton switch is open Contact is connected. When the pushbutton switch is open, the thyristor is the locking level switched through and therefore switches the control stage briefly. A switch-on pulse cannot be generated. This achieves the same effect as if there was a short circuit when the pushbutton switch was open known circuit arrangements, however, leads to the generation of a switch-on pulse.

In a further embodiment of the invention it is provided that the second locking stage is a series circuit contains a diode and a thyristor, · the with the closed pushbutton switch with the control stage is connected in parallel, which generates a voltage drop across a resistor when the pushbutton switch is closed,

... öer_über_a_ diode and a resistor to the The control electrode of the thyristor is placed in parallel with the Thyristor a capacitor is connected, the capacity of which is such that the current of the during a negative Half-cycle across the thyristor discharging capacitor does not fall below the holding current of the thyristor. Of the

The thyristor of the second locking stage is opened with a delay after the switch-on pulse has been generated in the control stage, in order to then short-circuit the control stage again. The capacitor connected in parallel
ensures that the thyristor of the second control stage remains switched on even during the opposite half-wave, so that it is ensured that only a single driving impact is generated even when the pushbutton switch is closed.

An exemplary embodiment of the invention is explained in more detail below with reference to drawings.

Fig. 1 shows a block diagram of the circuit arrangement according to the invention.

Fig. 2 shows a somewhat more detailed circuit arrangement with the feature of the invention.

Before going into the details shown in the drawings, it should be noted that
each of the features shown and described is essential to the invention either by itself or in conjunction with features of the claims.

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In Fig. 1, 10 denotes a solenoid of the rest not shown, conventional electric driving tool. The solenoid 10 is via a Circuit breaker 11 and a push button switch 12 connected in series with an AC voltage source 13. Of the Circuit breaker 11 is controlled by a control stage 14, which has a time delay stage 15 with the circuit breaker 11 is connected. A first stage of locking 16 is connected to the control stage 14 and is de-energized when the pushbutton switch 12 is open Contact of the push button switch 12 connected. A second locking stage 17 is also with the Control stage 14 connected and is acted upon by the voltage drop that occurs through a resistor R when Flow of a current through the coil 16 is generated.

The circuit arrangement according to FIG. 1 operates as follows. If the pushbutton switch 12 is open, the locking stage 16 ensures that a switch-on pulse for the circuit breaker 11 is not generated. By connecting the first locking stage 16 with that when the pushbutton switch is open 12 de-energized contact establishes the locking stage 16 when the pushbutton switch 12 is open. If, on the other hand, the pushbutton switch 12 is closed, voltage is also applied to the second locking stage 16 and

unlocks the control stage 14, so that this the power

switch 11 opens. Unlocking the control stage 14 takes place in such a way that only with a full, the closing of the pushbutton switch 12 following positive half-wave, a control pulse is generated so that the circuit breaker 11 and thus to the solenoid coil 10 a full half-wave is placed.

The current flow through the resistor R creates a voltage drop, which acts on the second locking stage 17 and also locks the control stage 14. There the second locking stage acts with a time delay, the locking by the second locking stage can only become effective after a first switch-on pulse • has been generated by control stage 14. Further switch-on impulses are therefore no longer generated, even if the pushbutton switch 12 remains closed.

The pushbutton switch is also designated by 12 in FIG. 2. The magnet coil bears the reference number 10. The magnet coil 10 is located with a power thyristor TH 3 in Row to AC voltage source L 1 / N. The push button switch 12 and a fuse are also located in this series connection F 1. The control electrode of the thyristor TH 3 is connected to an output electrode of an unjunction transistor

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T 2, the emitter electrode of which at a point between a Parallel connection of two resistors ρ 1 and R 13 and a capacitor C 4 is located. In series with the one mentioned A resistor R 10 is connected in parallel with the resistor.

The circuit components described are above one

-> Resistor R 8 and a diode 4 constantly at the pole L 1 of the AC voltage source. The other output electrode of the unjunction transistor T 2 lies across a resistor R 11 at a point between the diode D 4 and the resistor R 10. Between a point between the A thyristor TH 2 is connected to the resistor R 8 and the diode 4 and the other pole N of the AC voltage source.

The control electrode lies between a resistor R 9 and a capacitor connected in series with it C 3, which series connection is in series with a resistor R 7, which is also connected to the pole L 1 of the AC voltage source connected is. In parallel with the series connection of resistor R 9 and capacitor C 3 the emitter collector path of a transistor T 1, the base of which is connected to the open via a resistor R 6 Pushbutton switch 12 de-energized contact 2 of the pushbutton switch 12 is located. A series connection of a diode D 2, a Resistor R 5 and a capacitor C 2 connects the contact 2 of the push button switch 12 to the PoIn AC voltage source.

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A point between resistor R 5 and capacitor C 2

is via a resistor R 1 and a thyristor TH 1

\ connected to the pole ν of the voltage source. A cons

The position R 4 is in series with the power thyristor TH 3.

\ · The series circuit is parallel to the resistor R 4

] from a resistor R 3 and a diode D 1. This

Series connection is connected to the control electrode

j of the thyristor TH 1. In parallel with the control electrode TH 1

·] There are a capacitor C 1 and a resistor R 1.

Finally, a capacitor C 5 is connected in parallel to the poles L 1 and N of the AC voltage source.

The circuit arrangement shown in Fig. 2 operates as follows.

The thyristor TH 2 is at every 'positive half-wave Triggered somewhat delayed because of the capacitor C 3, around 6 V. The voltage at the rises accordingly Diode D 4 up to about 6 V, but drops to about 1.4 V after the thyristor TH 2 is triggered. At this Voltage, the thyristor TH 3 cannot be ignited by the ignition or trigger circuit. The ignition circuit is therefore locked.

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If the push button switch 12 is closed, the control current short-circuited for the control electrode of the thyristor TH 2 via the transistor T 1, the base of which is now connected to the voltage source. Was the thyristor TH 2 already ignited when the pushbutton switch 12 has been closed, an ignition pulse is still generated

not released because TH 2 remains conductive until the next zero crossing.

If, on the other hand, the pushbutton switch 12 is pressed before the zero crossing, or closed during the negative half-cycle, the control circuit for the thyristor TH 2 is via the resistor R 6 and the transistor T 1 short-circuited, so that the voltage at D 4 increases until the ignition pulse is given and the thyristor TH 3 can be ignited. After the triggering of the thyristor TH 3, the coil 10 of the Current flows through it, which generates a voltage drop of approx. 3.5 V at R 4. About the voltage drop at R 4 becomes The thyristor TH 1 is ignited via the diode D 1 and the resistor R 3, but with one through the capacitor C 1 caused a time delay. While the push button switch 12 is closed, a positive Half-wave of the capacitor C 2 charged. During the positive half-wave, a current also flows through the Diode D 2, the resistor R 5, the resistor R 1 and the thyristor TH 2 and via the resistor R 8, the

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Diode D 3 and thyristor TH 1. During the negative half-cycle the capacitor C 2 discharges through the resistor R 1. The capacitor C 2 is dimensioned in such a way that that the holding current of the thyristor TH 1 is not undershot. This means that as long as the push button switch 12 is closed, the thyristor TH 1 remains triggered and a new ignition pulse is generated via the diode D 3 and Thyristor TH 1 prevented. If the push button switch 12 is opened again, the thyristor TH 1 extinguishes after exceeding the holding current, i.e. after discharging the capacitor C 2. Now, after closing the Pushbutton switch 12 a new positive half-wave can be applied to the magnetic coil 10.

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Claims (3)

3.1 O 1 /. Expectations : 1 .j circuit arrangement for an electric kin driving device for driving nails. Brackets or the like with a magnetic coil connected to an alternating voltage above a circuit breaker, a control stage connected to the alternating voltage source which generates a switch-on pulse for the circuit breaker when a pushbutton switch is actuated, characterized in that the pushbutton switch (12) with the circuit breaker (11) and the magnetic coil (10) is connected in series, the control stage (14) is constantly connected to the AC voltage source (13), a first locking stage (16) connected to the control stage (14) suppresses the generation of a switch-on pulse as long as the pushbutton switch (12) is open and the control stage (14) only releases when a full half-wave is present after the pushbutton switch (12) is closed, and a second locking stage (17) connected to the control stage (14) suppresses the generation of a switch-on pulse after a first switch-on pulse has been generated is. - 14 - ■ ^: - ^: "- · -j- _wa - ■ .. 310U-VI ■ 2. Circuit arrangement according to claim 1, characterized in that the first locking stage (16) is constantly connected to the Contains AC voltage source connected, parallel to the control stage connected thyristor (TH 2), whose Control circuit is also constantly connected to the AC voltage source and the control circuit via a Transistor (T 1) is short-circuited, with the base which is connected to the voltage-free contact (2) when the pushbutton switch (12) is open. 3. Circuit arrangement according to claim 1 or 2, characterized in that the second locking stage is a Series connection of a diode and a thyristor '(TH 1), which when the pushbutton switch (12) is closed is connected in parallel with the control stage, the load current flowing when the pushbutton switch (12) is closed generates a voltage drop at a resistor (R 4), which is connected to the control electrode of the thyristor (TH 1) via a diode (D 1) and a resistor (R 3), and parallel to the thyristor (TH 1) a capacitor (C 2) • is connected, the capacity of which is dimensioned so that the current of the capacitor discharging through the thyristor (TH 1) during a half cycle is the holding current of the thyristor (TH 1) does not fall below. - 15 -