Hilti Aktiengesellschaft

Wolfgang Millauer

Helmut Burger

Walter Wissmach

Franz Hoyss

Manfred Spieth

Hanno Richter

Karl Echtler

Egon Konigbauer

Heinrich Pauli

Dieter Raab

Gottfried Benz

Pursuant to the invention, the capacitance of the smoothing capacitor in the direct current intermediate circuit, which normally must be designed relatively large in a main supplied direct current regulator, is divided into two capacitances, of which one capacitance (K ), responsible for the smoothing, continues to bridge the direct current side of rectifier (G), while the other capacitance (K ), which absorbs the demagnetizing energy of an inductive load (L), bridges the half-bridge of the bridge circuit, which is remote from the rectifier, wherein the connecting point between the two half-bridges of the bridge circuit is decoupled from a feeding point of the intermediate circuit by an additional third diode (D ). Due to the invention, feedback effects on the electrical network are reduced and high switching-on currents can be reduced by a large smoothing capacitance, which was previously required for other reasons.

Direct current-supplying circuit for inductances

The method and the arrangement for temperature monitoring of universal motors based upon a resistance measurement of a field winding, wherein a DC current component of low magnitude is superimposed upon the motor current for elimination of the complex values of the AC current impedance, and wherein the voltage drop in the field winding is amplified and freed from the AC voltage component and is compared as a DC voltage component proportional to the ohmic resistance of the field winding to a temperature independent DC voltage component, which is obtained in an analogous manner from a current measuring shunt, through which the motor AC current, including the superimposed DC current component, flows.

Method and apparatus for temperature monitoring of universal or AC/DC

A circuit arrangement is disclosed for a non-contacting switch-over of operational parameters in an electrically driven tool, for instance, a hammer drill, which are determined by a voltage divider ratio with reference to a stabilized supply source. The voltage divider ratio is obtained by selective parallel switching of an additional ohmic resistor by means of a Hall switch, whose current supply is supplied by a Zener diode which lies in series with the stabilized supply source. The circuit of the Hall switch puts the low point of the additional resistor, connected through a diode, to the low point of the voltage divider, in parallel with the partial resistor of the voltage divider, through a drop resistance. The switching arrangement or circuit arrangement has the advantage that the current supply of an RPM control unit is only slightly additionally loaded or increased.

Circuit arrangement for contactless switchover of operation parameters

A storage battery has an axially extending housing divided into axially extending blocks each containing a plurality of individual cells. The housing has a pair of plus-minus contact terminals equal to the number of blocks with the terminals accessible from the exterior of the housing. Voltage is supplied to each pair of terminals corresponding to the sum of the voltage of the cells within one block. The charging operation in the individual blocks is performed consecutively in an appropriately shaped charging device having a charging voltage corresponding to the voltage of one block. The voltage of the individual blocks can be utilized in series or in parallel connection by an appropriate electronic arrangement within an electrically driven tool.

Contact terminal arrangement in a storage battery

A revolutions per minute (RPM) control device for hand-held electric tools, such as drilling tools and hammer drills, has a RPM sensor in a separate housing or container from the control device housing. The sensor is connected to the control device by a flexible cable. The sensor extends through an opening in the drive motor housing of the electric tool. The RPM control device can be used for a plurality of similar types of tools.

Revolutions per minute regulation device for a hand-held electric tool

A battery operated device includes a circuit connecting a DC motor (22) and a battery (9) made up of a plurality of cells (10, 11, 12) connected in series with a two-pole switch device (23) including a first switch (24) and a second switch (25). The DC motor (22) receives a lower battery voltage from an intermediate tap (17) of the battery through a first switch (24) and it receives the full battery voltage through an end tap (15) when the second switch (25) is closed so that the motor can be operated at two speeds. Further, elements are provided for preventing a short circuit between the intermediate tap (17) and the end tap (15) of the battery (9) when the second switch (25) is closed. As a result of this switching arrangement, an extensively interrupted-switching is available, so that practically no power lapses occur when switching over from one speed to the other.

Battery operated device

Drive control for a drilling device including a universal motor is arranged so that the total available mains voltage is applied when a fraction of the motor torque, available for the full work range of the device, is reached. If a higher torque is desired, the motor torque/rotational speed curve follows the natural characteristic line until a load point is reached where current limitation occurs. Accordingly, as the motor speed decreases as the normal work range is exceeded, the operator of the drilling device is signaled concerning the load state due to the noise developed in the drilling device.

Drive control with overload protection for a drill device

A circuit for phase control of an AC-DC motor for a machine operated in defined (preferably two) load conditions with a controllable current flow control valve located in series with the motor and associated triggering pulse stage. The circuit includes a measuring circuit designed as a rectifier circuit with filter link for detection of the load current flowing through the load path of the current flow controller or through the motor as well as a threshold value circuit which determines a first basic desired value of the triggering voltage level at the triggering pulse stage at low load current values (idling). If a triggering threshold, adjustable at the triggering value circuit, is exceeded, then the triggering voltage level is switched over onto a second firmly or permanently adjusted value, so that the motor now operates at nominal load with nominal rpm through the current flow control valve, now controlled to be fully advanced. The circuit does not require any information about the instantaneous rpm and is distinguished by its simple construction and reliable operation. It is particularly suitable for utility machines, which operate either in idling or under nominal load conditions.

Circuit for phase section control of an AC-DC motor

Single or multi-track data markings are provided on the shank of a tool bit between a torque transmission region at one end and a working region proper for automatic working data set-up of a driving implement for exchangeable tool bits. The data markings consist of a sequence of notch-like depressions and lands, which are scanned by inductive proximity switch sensors. In case of multi-track codings, one track is used for clock timing. In case of single track codings, an rpm transmitter signal is used as a clock time signal during the information decoding in order to obtain an unequivocal identification signal. Signal evaluation occurs in a microprocessor with at least two counter register combinations, which alternately, in the sequence of the sensor signal, count the pulses of the time clock signal. The respective combination contents are compared in an evaluation unit of the microprocessor with prestored table values. In this way, appropriate driving parameters for each type of tool bit are made available for the motor drive.

Arrangement for automatic working data set-up for driving implements

For locating steel reinforcing members in construction materials, a galvanic cell is formed between an electrode and the reinforcing members by placing the electrode in electrically conducting contact with the construction material. When drilling an opening into the construction material using a hand-held drilling device and the drilling bit in the device contacts a reinforcing member, the potential difference between the electrode and the drill bit can be utilized as a signal for controlling the operation of the drilling device.

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Munich, Germany

Wolfgang Millauer