Apparatus and Method for Driving a Solenoid Valve

Abstract

The invention relates to an apparatus (1) and a method for driving a solenoid valve (3), having an evaluation and control unit (10), a PWM apparatus (20) and a current measuring apparatus (AM), wherein, in normal operation, the evaluation and control unit (10) generates a PWM signal (PWM) having a duty ratio (TV) and emits said PWM signal to a magnet assembly (3.1) of the solenoid valve (3) by means of the PWM apparatus (20), wherein the current measuring apparatus (AM) detects a current (I) through the magnet assembly (3.1) resulting from the PWM signal (PWM) and reports said current back to the evaluation and control circuit (10), wherein a current (I) that is above a response threshold of the magnet assembly (3.1) triggers a switching process of the solenoid valve (3), and wherein, in test operation, the evaluation and control circuit (10) generates and emits at least one test PWM signal (TPWM1, TPWM2) having a duty ratio (TV1, TV2) by means of the PWM apparatus (20), said at least one test PWM signal inducing a test current (IT1, IT2) that is below the response threshold through the magnet assembly (3.1), and to a hydraulic assembly having such an apparatus (1) for driving a solenoid valve (3). In this case, in test operation, the evaluation and control unit (10) generates and emits at least two different test PWM signals (TPWM1, TPWM2) and detects the resulting test currents (IT1, IT2), wherein the evaluation and control unit (10) derives presently prevailing ambient conditions from the predefined test PWM signals (TPWM1, TPWM2) and the resulting test currents (IT1, IT2) and, in normal operation, generates and emits a subsequent PWM signal (PWM) based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current (I) that is above the response threshold, for the purpose of switching the solenoid valve (3).

Claims

1. An apparatus (1) for driving a solenoid valve (3), having an evaluation and control unit (10), a PWM apparatus (20) and a current measuring apparatus (AM), wherein, in normal operation, the evaluation and control unit (10) generates a PWM signal (PWM) having a duty ratio (TV) and emits said PWM signal to a magnet assembly (3.1) of the solenoid valve (3) by means of the PWM apparatus (20), wherein the current measuring apparatus (AM) detects a current (I) through the magnet assembly (3.1) resulting from the PWM signal (PWM) and reports said current back to the evaluation and control circuit (10), wherein a current (I) that is above a response threshold of the magnet assembly (3.1) triggers a switching process of the solenoid valve (3), and wherein, in test operation, the evaluation and control circuit (10) generates and emits at least one test PWM signal (TPWM1, TPWM2) having a duty ratio (TV1, TV2) by means of the PWM apparatus (20), said at least one test PWM signal inducing a test current (IT1, IT2) that is below the response threshold through the magnet assembly (3.1), wherein, in test operation, the evaluation and control unit (10) generates and emits at least two different test PWM signals (TPWM1, TPWM2) and detects the resulting test currents (IT1, IT2), wherein the evaluation and control unit (10) derives presently prevailing ambient conditions from the predefined test PWM signals (TPWM1, TPWM2) and the resulting test currents (IT1, IT2) and, in normal operation, generates and emits a subsequent PWM signal (PWM) based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current (I) that is above the response threshold, for the purpose of switching the solenoid valve (3).

2. The apparatus (1) as claimed in claim 1, wherein the evaluation and control unit (10) generates a first test PWM signal (TPWM1) having a first duty ratio (TV1), said first test PWM signal inducing a first test current (IT1), and a second test PWM signal (TPWM2) having a second duty ratio (TV2), said second test PWM signal inducing a second test current (IT2), and emits said test PWM signals to the magnet assembly (3.1) of the solenoid valve (3) by means of the PWM apparatus (20), wherein the current measuring apparatus (AM) reports the resulting test currents (IT1, IT2) back to the evaluation and control unit (10).

3. The apparatus (1) as claimed in claim 2, wherein, for the presently prevailing ambient conditions, the evaluation and control unit (10) determines a present functional relationship between the duty ratios (TV1, TV2) and the resulting test currents (IT1, IT2) from the predefined duty ratios (TV1, TV2) of the test PWM signals (TPWM1, TPWM2) and the resulting measured test currents (IT1, IT2) and extrapolates, in normal operation, a corresponding duty ratio (TV) of the PWM signal (PWM), which is to be applied, by means of the functional relationship and generates and emits a corresponding PWM signal (PWM) by means of the PWM apparatus (20).

4. The apparatus (1) as claimed in one of claims 1 to 3, wherein the evaluation and control unit (10) generates and emits the different test PWM signals (TPWM1, TPWM2) within a predefinable time window or in an event-oriented manner or at predefined times by means of the PWM apparatus (20).

5. The apparatus (1) as claimed in one of claims 1 to 4, wherein, in normal operation, the evaluation and control unit (10) derives presently prevailing ambient conditions from the PWM signals (PWM) and the resulting currents (I) and, for a subsequent switching process, generates and emits a subsequent PWM signal (PWM) having a duty ratio (TV) based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current (I) that is above the response threshold, for the purpose of switching the solenoid valve (3).

6. A hydraulic assembly (5) having at least one solenoid valve (3) and at least one apparatus (1) for driving a solenoid valve (3), wherein the apparatus (1) for driving a solenoid valve (3) is embodied as claimed in one of claims 1 to 5.

7. A method for driving a solenoid valve (3), having the following steps: in normal operation, generating PWM signals (PWM) and emitting said PWM signals to a magnet assembly (3.1) of the solenoid valve (3), detecting resulting currents (I) through the magnet assembly (3.1), said currents being based on duty ratios (TV) of the PWM signals (PWM), and reporting said currents back, wherein a current (I) that is above a response threshold of the magnet assembly (3.1) triggers a switching process of the solenoid valve (3), wherein, in test operation, at least one test PWM signal (TPWM1, TPWM2) is generated and emitted, said test PWM signal inducing a test current (IT1, IT2) that is below the response threshold through the magnet assembly (3.1), distinguished by the following steps: in test operation, generating and emitting at least two different test PWM signals (TPWM1, TPWM2), detecting the resulting test currents (IT1, IT2), deriving presently prevailing ambient conditions from the predefined test PWM signals (TPWM1, TPWM2) and the resulting test currents (IT1, IT2), in normal operation, generating and emitting a subsequent PWM signal (PWM), which is based on the presently prevailing ambient conditions and induces a current (I) that is above the response threshold, for the purpose of switching the solenoid valve (3).

8. The method as claimed in claim 7, wherein a first test PWM signal (TPWM1) having a first duty ratio (TV1), said first test PWM signal inducing a first test current (IT1), and a second test PWM signal (TPWM2) having a second duty ratio (TV2), said second test PWM signal inducing a second test current (IT2), are generated and emitted to the magnet assembly (3.1) of the solenoid valve (3) and resulting test currents (IT1, IT2) are detected, wherein the different test PWM signals (TPWM1, TPWM2) are generated and emitted within a predefinable time window or in an event-oriented manner or at predefined times.

9. The method as claimed in claim 8, wherein, for the presently prevailing ambient conditions, a present functional relationship between the duty ratios (TV1, TV2) and the resulting test currents (IT1, IT2) from the predefined duty ratios (TV1, TV2) of the test PWM signals (TPWM1, TPWM2) and the resulting detected test currents (IT1, IT2) is determined and, in normal operation, a corresponding duty ratio (TV) of the subsequent PWM signal (PWM), which is to be applied, is extrapolated by means of the functional relationship and a corresponding subsequent PWM signal (PWM) is generated and emitted.

10. The method as claimed in one of claims 7 to 9, wherein, in normal operation, presently prevailing ambient conditions are derived from the PWM signals (PWM) and the resulting currents (I) and, for a subsequent switching process, a subsequent PWM signal (PWM) having a duty ratio (TV) is generated and emitted based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current (I) that is above the response threshold, for the purpose of switching the solenoid valve (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 shows a schematic block diagram of a section of an exemplary embodiment of a hydraulic assembly having an exemplary embodiment of an inventive apparatus for driving a solenoid valve.

[0016] FIG. 2 shows a characteristic curve diagram, which illustrates two test PWM signals emitted by a PWM apparatus of the apparatus for driving a solenoid valve from FIG. 1 and two resulting test currents.

EMBODIMENTS OF THE INVENTION

[0017] As can be seen from FIG. 1, a hydraulic assembly 5 has at least one solenoid valve 3 and at least one apparatus 1 for driving a solenoid valve 3. In the exemplary embodiment illustrated, the apparatus 1 for driving a solenoid valve 3 comprises an evaluation and control unit 10, a PWM apparatus 20 and a current measuring apparatus AM. In normal operation, the evaluation and control unit 10 generates a PWM signal PWM having a duty ratio TV and emits said PWM signal to a magnet assembly 3.1 of the solenoid valve 3 by means of the PWM apparatus 20. The current measuring apparatus AM detects a current I through the magnet assembly 3.1 or through a magnet coil (not illustrated in any more detail) of the magnet assembly resulting from the PWM signal PWM and reports the value of the detected current I back to the evaluation and control circuit 10, wherein a current I that is above a response threshold of the magnet assembly 3.1 triggers a switching process of the solenoid valve 3. In addition, in test operation, the evaluation and control circuit 10 generates and emits at least one test PWM signal TPWM1, TPWM2 having a duty ratio TV1, TV2 by means of the PWM apparatus 20, said at least one test PWM signal inducing a test current IT1, IT2 that is below the response threshold through the magnet assembly 3.1. Here, in test operation, the evaluation and control unit 10 generates and emits at least two different test PWM signals TPWM1, TPWM2 and detects the resulting test currents IT1, IT2. The evaluation and control unit 10 derives presently prevailing ambient conditions from the predefined test PWM signals TPWM1, TPWM2 and the resulting test currents IT1, IT2. In normal operation, the evaluation and control unit 10 generates and emits a subsequent PWM signal PWM based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current I that is above the response threshold, for the purpose of switching the solenoid valve 3. Since the resulting current I is not regulated, a countercurrent generated by an inductive coupling of the valve armature movement induces deceleration of the valve armature when impinging on a corresponding pole core, which results in a quieter switching noise of the solenoid valve 1 than in the case of a regulated current I.

[0018] As can further be seen from FIGS. 1 and 2, in the exemplary embodiment illustrated, the evaluation and control unit 10 generates a first test PWM signal TPWM1 having a first duty ratio TV1, said first PWM signal inducing a first test current IT1, and a second test PWM signal TPWM2 having a second duty ratio TV2, said second test PWM signal inducing a second test current IT2, and emits said test PWM signals to the magnet assembly 3.1 of the solenoid valve 3 by means of the PWM apparatus 20. The current measuring apparatus AM reports the resulting test currents IT1, IT2 back to the evaluation and control unit 10.

[0019] For the presently prevailing ambient conditions, the evaluation and control unit 10 determines a present functional relationship F(TV1, TV2, IT1, IT2) between the duty ratios TV1, TV2 and the resulting test currents IT1, IT2 from the predefined duty ratios TV1, TV2 of the test PWM signals TPWM1, TPWM2 and the resulting measured test currents IT1, IT2. The evaluation and control unit 10 extrapolates, in normal operation, a corresponding duty ratio TV of the PWM signal PWM, which is to be applied, by means of the functional relationship. The evaluation and control unit 10 generates and emits a corresponding PWM signal PWM by means of the PWM apparatus 20. The evaluation and control unit 10 can generate and emit the different test PWM signals TPWM1, TPWM2, for example, within a predefinable time window or in an event-oriented manner or at predefined times by means of the PWM apparatus 20.

[0020] In the exemplary embodiment illustrated, in normal operation, the evaluation and control unit 10 derives presently prevailing ambient conditions from the PWM signals PWM and the resulting currents I and, for a subsequent switching process, generates and emits a subsequent PWM signal PWM having a duty ratio TV based on the presently prevailing ambient conditions by means of the PWM apparatus 20, said subsequent PWM signal inducing a current I that is above the response threshold, for the purpose of switching the solenoid valve 3. As a result, it is possible to compensate for disturbance influences promptly, even without current regulation.

[0021] A corresponding method for driving a solenoid valve 3 comprises the following steps: in normal operation, generating PWM signals PWM and emitting said PWM signals to a magnet assembly 3.1 of the solenoid valve 3. Detecting resulting currents I through the magnet assembly 3.1, said currents being based on duty ratios TV of the PWM signals PWM, and reporting said currents back, wherein a current I that is above a response threshold of the magnet assembly 3.1 triggers a switching process of the solenoid valve 3. In test operation, at least one test PWM signal TPWM1, TPWM2 is generated and emitted, said test PWM signal inducing a test current IT1, IT2 that is below the response threshold through the magnet assembly 3.1. Here, in test operation, at least two different test PWM signals TPWM1, TPWM2 are generated and emitted and the resulting test currents IT1, IT2 are detected. Deriving presently prevailing ambient conditions from the predefined test PWM signals TPWM1, TPWM2 and the resulting test currents IT1, IT2. In normal operation, generating and emitting a subsequent PWM signal PWM, which is based on the presently prevailing ambient conditions and induces a current I that is above the response threshold, for the purpose of switching the solenoid valve 3.

[0022] As can be further seen from FIG. 2, a first test PWM signal TPWM1 having a first duty ratio TV1, said first test PWM signal inducing a first test current IT1, and a second test PWM signal TPWM2 having a second duty ratio TV2, said second test PWM signal inducing a second test current IT2, are generated and emitted to the magnet assembly 3.1 of the solenoid valve 3 and the resulting test currents IT1, IT2 are detected. The different test PWM signals TPWM1, TPWM2 are generated and emitted within a predefinable time window or in an event-oriented manner or at predefined times. For the presently prevailing ambient conditions, a present functional relationship between the duty ratios TV1, TV2 and the resulting test currents IT1, IT2 from the predefined duty ratios TV1, TV2 of the test PWM signals TPWM1, TPWM2 and the resulting detected test currents IT1, IT2 is determined. In normal operation, a corresponding duty ratio TV of the PWM signal PWM, which is to be applied, is extrapolated by means of the functional relationship and a corresponding subsequent PWM signal PWM is generated and emitted.

[0023] In this way, it is possible to more or less effectively compensate for the influence of temperature depending on the number or time interval of the test PWM signals TPWM1, TPWM2. The changing relationship between the duty ratios TV1, TV2 of the test PWM signals TPWM1, TPWM2 and the resulting test currents IT1, IT2 can be determined dynamically using the test PWM signals TPWM1, TPWM2, with the result that, in normal operation, the solenoid valve 1 can be operated as quietly as possible.

[0024] Furthermore, in normal operation, presently prevailing ambient conditions are derived from the PWM signals PWM and the resulting currents I and, for a subsequent switching process, a subsequent PWM signal PWM having a duty ratio TV is generated and emitted based on the presently prevailing ambient conditions, said subsequent PWM signal inducing a current I that is above the response threshold, for the purpose of switching the solenoid valve 3.

[0025] Embodiments of the present invention can be used in high-pressure switching valves in vehicle brake systems (ABS, ESP, etc.). The inventive principle of driving based on test PWM signals can be applied in pneumatic and hydraulic solenoid valves.