Rotary transmitter for machine tools
The invention relates to a rotary transmitter ( 2 ) for machine tools, having an inductive energy transmission section ( 31 ), which is arranged between a stator part ( 4 ) fixed to the machine and a rotor part ( 6 ) fixed to the tool, and a contactless bidirectional data transmission section ( 35 ). A special feature of the invention consists in that, in order to make maximum use of the capacity of the energy transmission section ( 31 ), precautions are taken with which the optimal operating frequency (f opt ) of the energy transmission operating according to the transformer principle is determined at every system start in a test run with a connected test resister ( 51 ) and a variable frequency (f p ). Furthermore, for the purpose of interference-free data transmission, buffer storage of the data to be transmitted via the data transmission section ( 35 ) is proposed, which data are synchronized in predefined time windows with interference-free periods of the energy transmission.
1. A rotary transmitter for machine tools, having an inductive transmission section for electrical power, having a stator part, which is fixed to a machine, and a rotor part, which is fixed to a tool and can rotate about a rotation axis, wherein the stator part has a primary winding, which is arranged in a primary circuit, and the rotor part has a secondary winding, which is arranged in a secondary circuit and is separated from the primary winding by means of an air gap, characterized in that an inverter is arranged in the primary circuit, a DC input of said inverter being connected to a DC source, an AC output of said inverter being connected to a primary resonant circuit which contains the primary winding, and it being possible to vary and adjust an operating frequency of said inverter by means of a control assembly, in that a rectifier is arranged in the secondary circuit, a secondary resonant circuit which contains the secondary winding being connected to an AC input of said rectifier, and a DC output of said rectifier being in a form of a load connection, in that the secondary circuit comprises a test resistor which can be selectively connected and bridges the load connection, in that an ammeter is arranged in the primary circuit at the DC input of the inverter, and in that the control assembly has a programmable actuating output, which is connected to a frequency input of the inverter, and a measurement input which is connected to or communicates with the ammeter.
2. The rotary transmitter as claimed in claim 1 , characterized in that the control assembly has an evaluation circuit or routine for storing and/or evaluating the measurement values, which are received by means of the measurement input in the form of measurement signals, as a function of the frequency values, which are output by means of the actuating output in the form of frequency signals, when the test resistor is connected, and also has a data memory for storing an optimum operating frequency which is calculated using the evaluation circuit or routine.
3. The rotary transmitter as claimed in claim 1 , characterized in that the control assembly sets the frequency of the alternating current, which is output by the inverter, to an operating frequency which is close to the resonant frequency of the secondary resonant circuit.
4. The rotary transmitter as claimed in claim 1 , characterized in that a respective transmission and reception element for contact-free bidirectional data transmission is arranged in the stator part and in the rotor part.
5. The rotary transmitter as claimed in claim 4 , characterized in that the stator-end and the rotor-end transmission element are connected to a respective control assembly which contains a buffer memory in which data packets for transfer to the associated rotor-end or stator-end reception element in a defined time window are stored, wherein the length of the time window is smaller than half the period of the alternating current which flows through the primary winding and/or the secondary winding, and wherein the start and the end of the time window are at a time interval from the successive zero crossings of the alternating current which flows through the primary winding and/or the secondary winding.
6. A rotary transmitter for machine tools, having an inductive transmission section for electrical power, having a stator part, which is fixed to a machine, and a rotor part, which is fixed to a tool and can rotate about a rotation axis, wherein the stator part has a primary winding, which is arranged in a primary circuit, and the rotor part has a secondary winding, which is arranged in a secondary circuit and is separated from the primary winding by means of an air gap, characterized in that an inverter is arranged in the primary circuit, a DC input of said inverter being connected to a DC source, an AC output of said inverter being connected to a primary resonant circuit which contains the primary winding, and it being possible to vary and adjust an operating frequency of said inverter by means of a control assembly, in that a rectifier is arranged in the secondary circuit, a secondary resonant circuit which contains the secondary winding being connected to an AC input of said rectifier, and a DC output of said rectifier being in a form of a load connection, in that the secondary circuit comprises a test resistor which can be selectively connected and bridges the load connection, in that a voltmeter, which records a voltage drop across the test resistor, is arranged in the secondary circuit, and in that the control assembly has a programmable actuating output, which is connected to a frequency input of the inverter, and also a measurement input which communicates wirelessly with the voltmeter.