Adjusting Device, Motor-Driven Valve and Method for Operating an Adjusting Device

Abstract

An adjusting device having a DC motor and an adjusting member driven by an output shaft of the DC motor is disclosed. The adjusting device has a power driver coupled to the DC motor for controlling a motor current of the DC motor, a current measurement circuit that is adapted to detect a current consumption of the DC motor and to output a current measurement signal dependent on the number of revolutions of the DC motor, and a computing unit, to which the current measurement signal is input adapted to determine the number of revolutions of the DC motor based on the current measurement signal.

Claims

1. An adjusting device (10), comprising a DC motor (12) and an adjusting member driven by an output shaft of the DC motor (12), further comprising: a power driver (20) coupled to the DC motor (10) for controlling a motor current of the DC motor (10), a current measurement circuit (14) which is adapted to detect a current consumption of the DC motor (12) and to output a current measurement signal dependent on the number of revolutions of the DC motor (12), and a computing unit (18), to which the current measurement signal is input, adapted to determine the number of revolutions of the DC motor (12) based on the current measurement signal.

2. The adjusting device (10) according to claim 1, wherein the computing unit (18) is designed to determine the number of revolutions of the DC motor (12) based on a ripple of the current measurement signal, in particular based on pulses of the current measurement signal.

3. The adjusting device (10) according to claim 1, further comprising an electrical filter connected downstream of the current measurement circuit (14), adapted to block low-frequency components of the current measurement signal and to pass high-frequency components of the current measurement signal.

4. The adjusting device (10) according to claim 3, further comprising an amplifier (16) coupled to the electrical filter, adapted to amplify the output signal of the electrical filter.

5. The adjusting device (10) according to claim 4, wherein the computing unit (18) is connected downstream of the amplifier (16), adapted to read in the filtered and/or amplified current measurement signal.

6. The adjusting device (10) according to claim 5, wherein the computing unit (18) is coupled to the power driver (20) for controlling the motor current of the DC motor (12).

7. The adjusting device (10) according to claim 6, wherein the computing unit (18) is configured to control the power driver (20) based on the detected number of revolutions of the DC motor (12).

8. The adjusting device (10) according to claim 7, wherein the computing unit (18) is adapted to control the DC motor (12) such to move the motor-driven adjusting member to at least one predetermined position.

9. The adjusting device (10) according to claim 7, wherein the computing unit (18) is adapted to control the power driver (20) such to move the motor-driven adjusting member to at least one predetermined position.

10. The adjusting device (10) according to claim 8, wherein the computing unit (18) is further adapted to control the DC motor (12) such to track a change in the position of the adjusting member.

11. The adjusting device (10) according to claim 8, wherein the predetermined position comprises at least a closed position and/or an open position of the motor-driven adjusting member.

12. A motor-driven valve, comprising an adjusting device (10) according to claim 1.

13. A method for operating an adjusting device (10) according to claim 1, comprising the steps of: detecting a current consumption of the DC motor (12), generating, based on the detected current consumption, a current measurement signal dependent on the number of revolutions of the DC motor (12), and determining the number of revolutions of the DC motor (12) based on the current measurement signal.

14. The method according to claim 13, further comprising the step of: determining the position of the adjusting member based on the determined number of revolutions of the DC motor (12).

15. The method according to claim 13, wherein the number of revolutions of the DC motor (12) is determined based on a ripple of the current measurement signal, in particular based on pulses of the sensor signal.

Description

[0020] In the following, the present invention is further explained with reference to exemplary embodiments shown in the drawing, wherein:

[0021] FIG. 1 shows a block diagram of an adjusting device according to an exemplary embodiment, and

[0022] FIG. 2 shows a diagram of a voltage curve.

[0023] FIG. 1 shows a block diagram of an adjusting device 10 according to an exemplary embodiment. The adjusting device 10 comprises a motor, which according to the invention is designed as a DC motor 12. The DC motor 12 has an output shaft via which an adjusting member of the adjusting device is driven. The adjusting member may be designed as a valve body of a valve. A current measurement circuit 14 taps a current consumption of the DC motor 10, and outputs a current measurement signal to an amplifier 16 depending on the number of revolutions of the DC motor 10. The current measurement signal has a ripple caused by changes in current when a commutator of the DC motor 10 reverses polarity.

[0024] Although not shown, the current measurement signal may pass through at least one high pass filter that blocks low frequency components of the current measurement signal and passes high frequency components of the current measurement signal. The high-pass-filtered current measurement signal may be output to the amplifier 16. Alternatively or additionally, a high-pass filter may be connected downstream of the amplifier 16. Optionally, the amplifier 16 may be omitted and only a high-pass filter may be connected downstream of the current measurement circuit 14.

[0025] The current measurement signal passed through at least one high-pass filter is input to a computing unit 18. This computing unit 18 is coupled to a power driver 20, which is configured to control a motor current supplied to the DC motor 12. Here, the computing unit 18 may be configured to control the power driver 20 based on the detected number of revolutions of the DC motor 12. Thus, a control loop can be implemented.

[0026] The computing unit 18 can control the DC motor 12 in such a way as to move the driven adjusting member to at least one predetermined position. Optionally, the computing unit 18 can control the power driver 20 in such a way as to move the driven adjusting member to at least one predetermined position. The computing unit 18 may further drive the DC motor 12 in such a way as to track a change in the position of the adjusting member, wherein the predetermined position may be a closed position and/or an open position of the motor-driven adjusting member.

[0027] The adjusting device 10 determines the “steps” of the DC motor 12. As a result, the position of the DC motor 12 and optionally, for example, of a cartridge can be concluded. For this purpose, an initial position, e.g. a stop or a closed position and/or an open position of the motor-driven adjusting member, should be known. The adjusting device 10 detects the change in current when the polarity of the commutator of the DC motor 12 is reversed. Since the commutator is firmly coupled to the drive shaft of the DC motor 12, it is possible to reliably infer the revolutions made and thus the position of the driven adjusting member in a previously unknown manner.

[0028] The adjusting device 10 first measures the current drawn by the DC motor 12. This current can then be high-pass filtered so that only fast changes are processed. These changes can be amplified to such an extent that they can be read in directly, for example by the computing unit 18. In this way, the path traveled can be continuously tracked while moving, and the absolute position can be inferred from this. The invention makes it possible to retain the advantages of the DC motor 12 in battery operation and at the same time to omit an encoder.

[0029] FIG. 2 illustrates an exemplary curve of a voltage I_mot tapped directly at the DC motor of the adjusting device shown in FIG. 1, and an exemplary voltage curve I_imp resulting from processing on the directly tapped voltage I_mot. A bias voltage of the voltage I_mot tapped directly at the DC motor is at a potential of +1 V. The course or the ripple of the voltage I_mot tapped directly at the DC motor results from current changes when the polarity of the commutator of the DC motor is changed. Pulse-like changes can already be seen here, each with a time interval of 2 ms. The respective amplitudes, starting from the zero line, do not exceed the span of +/−0.5 V.

[0030] This directly tapped voltage I_mot is subjected to the processing described above consisting of at least one high-pass filtering and one amplification. This results in clearly recognizable pulses (I_imp) in a voltage range between 0 V and +3 V and the likewise clearly recognizable time interval of 2 ms between adjacent pulses. From the frequency of 500 Hz that can be derived from this, conclusions can be drawn about the speed of the DC motor and thus the number of revolutions of the DC motor. Starting from a reference position of the adjusting member, e.g. a stop of the adjusting member in the closed position, it is possible to continuously track the position of the adjusting member. Advantageously, no further components, e.g. encoders, etc., are required for this. Another advantage is that a DC motor can be used, which can be operated with battery voltage.