DE2933779A1 - CIRCUIT ARRANGEMENT FOR AN ELECTRIC DRIVER - Google Patents

Description

.NIiO KMiAMC Μϋ7Λ> C 3 3 3 7 7 9

dipl.-ing. II. HAUCK · dipi. -virvs-W. .SCLTAiITZ · dipl.-ing. E. GIiAA LFS L.-ING. W. WEHNERT Dipl.-Phys. AV. CAIlSTENS dr.-ing. AV.

HAMBURG-MUNICH-DÜSSELDORF

• PATENTA.NWJLTE · NEUER WAU 41 · 20OO HAMBURG ~ 6 ·

NEW WALLIL2OOO HAMIUIHG. ¹ IO TELEFON + TELECOPIER (040) 3 (1 67 B5 TELKX 02 Il 7 (19 INPAT D

Esco Metallwaren cable neqedapatent hambuhq

HAUCK-CARSTEJVS

Martin Hühnken MOZARTSTRASSEaa-soooMüxciiKNa

TELEPHONE + TELECOPIER (OSB) 03 Oa 3 (1 _ ", __. _ _. - _ CABLE NEQEDAPATENT MUNICH

Rudolf-Diesel-Strasse 7

WEHNERT-DÖR1NG

2072 Bargteheide. ^ «H ^ Ne ^^ jODü ^ nonrix

TELEX 08 584 380 DVNA D 29 287 CABLE NEQEDAPATENT DÜSSELDORF

ADDRESS FOR SERVICE / PLEASE REPLY TO: HAMBURG, August 17, 1979

Circuit arrangement for a electric driving tool

The invention relates to a circuit arrangement i

for an electric driving tool for driving

Nails, staples, or the like, with one over a J

Circuit breaker on AC voltage magnetic

! coil, one connected to the AC voltage source,

a control stage containing a pushbutton switch, which is

activated a pushbutton switch a switch-on pulse for the power

t switch generated. :

130013/0354!

APPROVED REPRESENTATION AT THE VROPEAN PATENT OFFICE i ADMITTED RKlMtKSKNTATIVKS HKCOItK TUE ΚΓΙΙΟΡΕΑΝ ΓΛΤΕΝΤ OFFICE j

· "" '"'» In «ία. THKÄunn inn 300 700 00) n«. O. "i / a8d '» 7' iwiw.vtx HANK »α. niimniu <No.T. 200 8O (»« IO> »» .033 00 8Βτοητ »γηπγκ am itHia-anO;

ORIGINAL INSPECTED

The basic structure of an electric driving tool has been around since Known for a long time (DE-PS 1A78 899). The driving ram for the nails or staples is part of a ferromagnetic » Immersion armature or is formed by this, which is inserted into a magnetic pulo is drawn into it when this is connected to the voltage source. A return spring ensures the return of the driving ram 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. The power thyristor is connected to the AC voltage in ± n series with the magnetic coil.With the help of a pulse circuit, the control electrode of the power thyristor is activated via another thyristor and this is ignited when the pushbutton of the driving device is pressed (DE-OS 2 238 44O).

In the case of the known driving tools, it is to be regarded as disadvantageous that the impact force made available is essentially is constant * The available impact force depends on the magnetic coil used and the one used Immersion anchor and therefore cannot be increased for a given device. However, there are numerous use cases in which a lower driving force is desired, for example by To keep damage to the surface of the workpiece as low as possible. In order to do justice to all applications in practice edtio series of driving tools has to be different Clout are made available.

130013/0354,.

ORIGINAL INSPECTED

The invention is based on the Aufgr.be, an electrical To create a driving device for nails, staples or the like, in which the impact force is set to different values leaves"

In the case of a driving tool, this task is the one mentioned at the beginning Kind of solved in that an auxiliary control stage is provided with a zero crossing detector that emits an auxiliary control pulse only outputs to the control stage when a positive or negative half-wave of the AC voltage source is just passing through The auxiliary control pulse goes to zero or has passed through zero is in phase with the AC voltage and the control stage contains a time delay stage with which the switch-on pulse is delayed in terms of time compared to the auxiliary control pulse can.

The invention assumes that a half-wave is switched to the magnet coil via the circuit breaker when maximum impact is required. Will the circuit breaker by a certain amount after zero crossing of the half-wave open, the solenoid then only has the remainder of the half-wave available, with the result that the drive-in energy is reduced by this amount.

130013/0354

ORiGiNAL! NSFECTED

When the pushbutton of the driving tool is actuated, the operator cannot of course know how at this point in time the phase position of the voltage is therefore a Zero crossing detector provided, which prevents the output of a switch-on pulse to the circuit breaker if At the moment the button of the driving tool is switched on, the alternating voltage is somewhere between the zero crossings is located. The switch-on pulse level is only activated via the auxiliary control pulse level with the subsequent zero crossing activated to close the circuit breaker · With With the help of the time delay stage, it is then possible to adjust the To move the switching point of the closing of the circuit breaker and thus the driving force of the driving device to change, from zero to the maximum driving force in a continuously variable manner.

In this way it is possible to use one and the same driving tool to nail even very sensitive materials without damaging them.For example, with the help of the driving tool according to the invention it is possible to drive staples into soft wood of h mm as well as of 18 mm without fear of damage.

In one embodiment of the invention it is provided that a half-wave pulse is applied to the time delay stage in the control stage is given. It goes without saying that the half-wave pulse which the control stage gives to the time delay stage in

130013/0354 / «

ORIGINAL INSPECTED

Phase is to AC voltage at the circuit breaker. In this way it is easily possible to use an RC element with changeable Resistance to vary the trigger time of the circuit breaker.

The teaching of the invention can be implemented with various circuit arrangements be realized. An advantageous embodiment provides for this that the control stage has an AC voltage has lying thyristor, the control electrode of which is connected to an ignition capacitor via a controllable electronic switch can be applied, the zero crossing detector also has a thyristor, the control electrode of which is connected to the AC voltage source is connected that the second thyristor is switched through immediately after the zero crossing and the control input of the controllable switch is deactivated. The controllable electronic switch is when the pushbutton switch is actuated Impulse on the first thyristor so that it ignites the power thyristor. However, the second thyristor ensures that the electronic switch is locked if at the time of actuation of the pushbutton switch the half-wave of the AC voltage is between the zero crossings. Only when the half-wave (positive or negative) the next If the zero crossing is reached or shortly thereafter, the electronic switch allows the ignition of the first thyris + ors.

130013/0364

ORIGINAL INSPECTED

-y-

According to a further embodiment it is provided that the controllable switch is a transistor, the base of which is connected to one pole of the AC voltage source as well as to a Electrode of the second thyristor is connected, while its collector-emitter path is connected to the control electrode of the first thyristor is connected,

Embodiments of the invention are explained in more detail below with reference to drawings.

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

Fig. 2 shows a more detailed structure of a circuit arrangement according to the invention.

Fig. 3 shows some diagrams to explain the function the circuit arrangement according to Fig. 2 «

Before going into the details shown in the drawings in more detail, it is prefixed that each of the Characteristics described on their own or in conjunction with characteristics the claims are essential to the invention "

In Fig. 1, 10 denotes the solenoid of the rest not shown, conventional electric driving tool. The solenoid 10 is over a circuit breaker 11 connected to an alternating voltage source 12 · In series

130013/0354.

ORIGINAL INSPECTED

with a push button switch 13 of the driving device (not shown); * a switch-on pulse stage 14 is connected to the VechseIpsannungsquelle 12. The Einsehaltimpulsstufe 14 gives impulses to a time delay stage 15 »which in turn controls the circuit breaker 11. The control pulse stage lh is in turn activated by an auxiliary control pulse stage 16, which in turn is controlled by a zero crossing detector.

The circuit arrangement according to FIG. 1 operates as follows. If the push-button switch 13 is closed, the switch-on pulse stage lh sends a switch-on pulse to the power switch 11 in order to close it and apply voltage to the magnetic coil 10. The circuit breaker is only opened for half a wave of the alternating voltage and then closes again. The auxiliary control pulse stage 16 prevents the switch-on pulse for the circuit breaker from being emitted at any point in time. Rather, the zero crossing detector ensures that a switch-on pulse is only given to the circuit breaker 11 when the alternating voltage has just passed through zero or has passed through zero. From a certain distance to the previous zero crossing, the switch-on pulse stage is blocked and the circuit breaker 1 " remains open. Only at the next zero crossing does the zero-crossing detector activate the auxiliary control pulse stage 16, which in turn activates the switch-on pulse stage 14 in order to close the circuit breaker 11. The time delay device.

130013/0354 ... / 8

However, level 15 gives the switch-on impulse depending on the setting delayed on the control input of the power switch 11 veiter, so that the closing of the circuit breaker with respect to the reference zero crossing of the AC voltage can be changed. Correspondingly, a whole half-wave can or only part of the circuit breaker 11 the solenoid 10 is applied «

In FIG. 2, the magnetic coil is also designated by 10. The pushbutton switch, however, is marked with S 1. The solenoid 10 is connected to a power thyristor Th 3 in series with the AC voltage source L1 / N. A parallel circuit of a variable resistor R7 and a potentiometer R 8 is connected in series with a triac D4 and connected to the control electrode of the power thyristor Th3. One terminal of a capacitor C k is connected to a point between the resistor parallel circuit and the triac, the other terminal of which is connected to the pole N. A further capacitor C 5 is located behind the triac in parallel with the capacitor C 4. A no-load diode D 5 is connected in parallel with the magnet coil.

Parallel to the series connection of the thyristor Th 3 and the magnetic coil 10 is a series connection of a thyristor Th 1 and a resistor R 6 at the voltage source »One point between thyristor Th 1 and a resistor R 6 at the voltage source between thyristor Th 1 and resistor R 6 1st connected to the resistor parallel circuit R 7 / R 8. The control electrode

130013/0354

- / 9

The thyristor Th 1 is connected to the emitter of a transistor T whose collector is connected via a capacitor C 3 to a connection point between two series-connected diodes D 2 and D 3. The other electrode of the diode D 2 is connected to the push button switch S 1 at the pole N. The base of the transistor T 1 is connected to the pole L 1 via the series resistors R 5 and R 2. A series circuit of a resistor R h and a capacitor C 2 is connected in series with the resistor R 6 to the AC voltage source. Another thyristor Th 2 has one electrode connected to a connection point between resistors R 5 and R 2, while the other electrode is connected to a connection point between thyristor Th 1 and resistor R 6. The control electrode of the thyristor Th 2 is located at a connection point between the resistor R h and the capacitor C 2.

A resistor R 1 is connected between the emitter of the transistor T 1 and the control electrode of the thyristor Th 1, the other pole being at a connection point between the thyristor Th 1 and the resistor R 6. At a connection point between the emitter of the transistor T 1 and the resistor R 1, a diode D 1 is connected, the other electrode of which is connected to one terminal of a parallel circuit of a resistor R 3 vaxd a capacitor C 2, which is at a point between the resistor R 2

130013/0354

.. • / ίο

and the base of the transistor T 1 is connected. The other The terminal of the parallel circuit R 3 / C 2 is also at a connection point between the thyristor Th 1 and the resistor R 6 ".

The circuit arrangement according to FIG. 2 operates as follows. The transistor T 1 receives its base current via the resistors R 5 and R 2. However, since the thyristor Th 2 is ignited by means of the P./C element R h / GZ at the beginning of the half-wave, it switches the control voltage for the transistor T 1 away. Therefore, if the pushbutton switch S 1 is pressed at any point in time between the zero crossings of a half-wave, the pulse given by the capacitor C 3 to the collector of the transistor T 1 cannot do anything, ie the thyristor Th 1 remains unfired. If the pushbutton switch S 1 remains pressed, a pulse can now be sent from the capacitor C 3 via the collector-emitter path of the transistor T 1 to the control electrode of the thyristor Th 1, since control voltage is still applied to the transistor T1 during the zero crossing or immediately thereafter . Thus, the thyristor Th 1 is only triggered at the beginning of a half-wave and lets it through completely. The voltage at the resistor R 6 is used via the carrier circuit consisting of the capacitors C 4 and C 5 and the triac D k to ignite the power _{thyristor T1 >> 3 t,} which then applies voltage to the magnet coil 10. The ignition timing of the thyristor Th3 can be adjusted by changing the resistor R 8 in order to increase the power of the magnet

130013/035Λ

ORIGINAL

coil 10 per half-wave and thus the desired impact force.

The change in the impact force is particularly clear on the basis of the diagrams according to FIG. 3. The top diagram shows the Curve progression of the voltage of the AC voltage source L 1 / N. The illustration below marks the point in time at which a Button is pressed. The subsequent positive half-wave is due to the functional sequence described above from the thyristor Th 1 to the resistor R 6 passed. This can be recognized by the representation in the diagram by adding the voltage U R6 dropping across resistor R 6 is shown. As explained, however, the ignition point of the power thyristor Th 3 can be changed, namely between full Half wave and zero. This is explained in the bottom diagram according to FIG Solenoid 10 reproduces.

130013/0354

Claims (4)

933779 A_n sgrüche t 1. Circuit arrangement for an electrical driving device for Driving in nails, staples or the like with an AC voltage connected to a circuit breaker Magnetic coil, one connected to the AC voltage source, a control stage containing a pushbutton switch which, when the pushbutton switch is actuated, provides a Einsehaltimpuls for generates the circuit breaker, characterized in that an auxiliary control stage (16) is provided with a Zero crossing detector (17) »the one auxiliary control pulse on tax bracket (i4) only if a positive or negative half-wave of the AC voltage source (12) just goes through zero or has gone through zero, the Auxiliary control pulse is in phase with the AC voltage and the control stage (14) contains a time delay stage (i4), with that of the switch-on pulse compared to the auxiliary control pulse can be delayed * 2, circuit arrangement according to claim 1, characterized in that a half-wave pulse is given to the time delay stage (15) in the control stage (lh). ... / 13 130013/0354 ORIGINAL INSPECTED 3, circuit arrangement according to claim 1 or 2, characterized in that that the control stage has a thyristor (Th 1) connected to alternating voltage and its control electrode via a controllable electronic switch (T 1) to one Z + ndcondenser (C 3) can be applied, the zero crossing detector also has a thyristor (Th 2), the control electrode of which so connected to the AC voltage source that the second thyristor (Th 2) immediately after Zero crossing is switched through and the control input of the controllable switch (Ti) deactivated, 4. Circuit arrangement according to claim 3 »characterized in that that the controllable switch is a transistor (Ti), its base both on one pole of the AC voltage source and on one electrode of the second thyristor (Th 2) connected 1st, while its collector-emitter path is connected to the control electrode of the first thyristor (Th 1) is. 130013/0354 ORIGINAL INSPECTED