Abstract
A method for switching over a solenoid valve having a movable valve body between a first position and a second position, wherein the method comprises at least the following method steps: a) adjusting a switching current to a pre-energization current intensity, in which the valve body remains in the present position, for a first time interval, and b) adjusting the switching current to a first switchover current intensity, which introduces a switchover movement of the valve body, for a second time interval.
Claims
1. A method for switching over a solenoid valve having a movable valve body between a first position and a second position in a first direction against a force generated by a restoring spring, the force generated by the restoring spring being in a second direction that is opposite the first direction, the method comprising: a) adjusting a switching current to a pre-energization current intensity in which the movable valve body remains at the first position for a first time interval; and b) adjusting the switching current from the pre-energization current to a first switchover current intensity for a second time interval which initiates a switchover movement of the valve body in the first direction to the second position.
2. The method as claimed in claim 1, wherein a duration of the second time interval is such that the switching over the solenoid valve has not yet been completed after the second time interval.
3. The method as claimed in claim 1, further comprising: c) adjusting the switching current to a damping current intensity which adjusts a speed of the switchover movement for a third time interval.
4. The method as claimed in claim 1, wherein the solenoid valve is switched over from the first position to the second position in response to the switching current having a current intensity above an upper limiting current intensity, the pre-energization current intensity being below the upper limiting current intensity.
5. The method as claimed in claim 4, wherein the pre-energization current intensity is at least 90% of the upper limiting current intensity.
6. The method as claimed in claim 1, wherein the solenoid valve is switched over from the second position to the first position in response to the switching current having a current intensity below a lower limiting current intensity, the pre-energization current intensity being above the lower limiting current intensity.
7. The method as claimed in claim 6, wherein the pre-energization current intensity is at most 110% of the lower limiting current intensity.
8. The method as claimed in claim 1, further comprising: d) adjusting the switching current to a second switchover current intensity which ensures that the switchover of the solenoid valve is carried out.
9. The method as claimed in claim 8, further comprising: monitoring for a setting of the solenoid valve at least for a duration of step d).
10. The method as claimed in claim 8, further comprising: repeating at least a), b), and d) to perform a multiplicity of switching operations, wherein, in a subsequent switching operation of the multiplicity of switching operations, the valve body is accelerated at an increased rate in the second time interval in response to a switchover of the solenoid valve being detected in step d) of at least one previous switching operation of the multiplicity of switching operations.
11. The method as claimed in claim 8, further comprising: repeating at least a), b), and d) to perform a multiplicity of switching operations, wherein, in a subsequent switching operation of the multiplicity of switching operations, the valve body is accelerated at a lower rate in the second time interval in response to no switchover of the solenoid valve being detected in step d) of at least one previous switching operation of the multiplicity of switching operations.
12. A control device for switching over a solenoid valve having a movable valve body between a first position and a second position in a first direction against a force generated by a restoring spring, the force generated by the restoring spring being in a second direction that is opposite the first direction, the control device configured to: a) adjust a switching current to a pre-energization current intensity in which the movable valve body remains at the first position for a first time interval; and b) adjust the switching current from the pre-energization current to a first switchover current intensity for a second time interval which initiates a switchover movement of the valve body in the first direction to the second position.
13. The control device according to claim 12, wherein the control device is configured to execute a computer program to adjust the switching current.
14. The control device according to claim 13, wherein the computer program is stored on a machine-readable storage medium.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further details of the disclosure and an exemplary embodiment, to which the disclosure is not limited however, are described in greater detail on the basis of the drawings. Shown are:
(2) FIG. 1: a schematic illustration of a solenoid valve;
(3) FIG. 2: a schematic waveform of a switching current when the solenoid valve of FIG. 1 switches over from a first position to a second position,
(4) FIG. 3: a schematic waveform of a switching current when the solenoid valve of FIG. 1 switches over from the second position to the first position, and
(5) FIG. 4: a schematic waveform of a switching current when the solenoid valve of FIG. 1 repeatedly switches over from the first position to the second position.
DETAILED DESCRIPTION
(6) FIG. 1 shows a solenoid valve 1 with a valve body 4, which is adjustable between a first stop 16 and a second stop 17. At the first stop 16 the valve body 4 is located in a first position. At the second stop 17 the valve body 4 is located (as shown in this drawing) in a second position. The solenoid valve 1 has a channel 5 between an inlet 6 and an outlet 7. The channel 5 is released in the second position (shown here) of the valve body 4, so that the solenoid valve 1 is open. In this case, a medium can flow out from the inlet 6 through the channel 5 past the valve body 4 to the outlet 7 and thus out of the solenoid valve 1. If the valve body 4 blocks the channel, on the other hand, the solenoid valve 1 is closed and the medium cannot flow out of the solenoid valve 1 or out of the outlet 7. In the solenoid valve 1 an electrical coil 2 is arranged, which—depending on the current flow through the electrical coil—exerts a magnetic force on the valve body 4 in a first direction (here upwards). The valve body 4 is connected to a spring 3, which exerts a force on the valve body 4 in a second direction 19 (here downwards). The solenoid valve 1 is connected to a control unit 15 via which the solenoid valve 1 can be switched over. To do so, the electrical current shown in FIGS. 2 and 3 is passed through the electrical coil 2.
(7) FIGS. 2 and 3 each show a current intensity I plotted against time t (in arbitrary units in both cases). Shown is the time characteristic of a switching current 8 for switching over the solenoid valve 1 from FIG. 1 from the first position into the second position (FIG. 2) or from the second position into the first position (FIG. 3). The switching current 8 is shown in idealized form. In addition, with a thinner line compared to the switching current 8, a real switching current 21 is shown, in which changes due to self-induction occur only after a time delay. The first position is assigned a first holding current intensity I.sub.A and the second position is assigned a second holding current intensity I.sub.B. Also shown is an upper limiting current intensity 9, wherein the solenoid valve 1 can be switched over from the first position to the second position due to the presence of the switching current 8 with a current intensity above the upper limiting current intensity 9. In addition, a lower limiting current intensity 10 is drawn, wherein the solenoid valve 1 can be switched over from the second position to the first position due to the presence of the switching current 8 with a current intensity below the lower limiting current intensity 10.
(8) FIG. 2 shows the switchover of the solenoid valve 1 from the first position to the second position. The solenoid valve 1 is in the first position up to a start time t.sub.0. To this end, the first holding current intensity I.sub.A is applied. In a first time interval 11 between the start time to and a first time t.sub.1, the switching current 8 is set to a pre-energization current intensity I.sub.1, in which the valve body 4 remains in the present position (that is, in the first position). The pre-energization current intensity I.sub.1 is below the upper limiting current intensity 9. In addition, the pre-energization current intensity I.sub.1 amounts to 90% of the upper limiting current intensity. In particular, it should be noted that for the sake of clarity, FIG. 2 is only schematic and not exactly to scale. Between the first time t.sub.1 and a second time t.sub.2, in a second time interval 12, the switching current 8 is set to a first switchover current intensity I.sub.2, which initiates a switchover movement of the valve body 4. The length of the second time interval 12 is chosen in such a way that the switchover of the solenoid valve 1 has not yet been completed after the second time interval 12. Between the second time t.sub.2 and a third time t.sub.3, in a third time interval 13 the switching current 8 is set to a damping current intensity I.sub.3, which adjusts, in particular reduces, a speed of the switchover movement. This can reduce noise produced on the impact of the valve body 4 on the second stop 17. Between the third time t.sub.3 and a fourth time t.sub.4, in a fourth time interval 14, the switching current 8 is set to a second switchover current intensity I.sub.4, which ensures that a switchover of the solenoid valve 1 has taken place. After the fourth time t.sub.4 the solenoid valve 1 is in the second position. Therefore, the second holding current intensity I.sub.B is applied.
(9) FIG. 3 shows the switchover of the solenoid valve 1 from the second position into the first position is shown. The solenoid valve 1 is in the first position up to a start time to. To this end, the second holding current intensity I.sub.B is applied. In a first time interval 11 between the start time to and a first time t.sub.1, the switching current 8 is set to a pre-energization current intensity I.sub.1, in which the valve body 4 remains in the present position (that is, in the second position). The pre-energization current intensity I.sub.1 is above the upper limiting current intensity 10. In addition, the pre-energization current intensity I.sub.1 amounts to 110% of the upper limiting current intensity. In particular, it should be noted that for the sake of clarity, FIG. 3 is only schematic and not exactly to scale. Between the first time t.sub.1 and a second time t.sub.2, in a second time interval 12, the switching current 8 is set to a first switchover current intensity I.sub.2, which initiates a switchover movement of the valve body 4. The length of the second time interval 12 is chosen in such a way that the switchover of the solenoid valve 1 has not yet been completed after the second time interval 12. Between the second time t.sub.2 and a third time t.sub.3, in a third time interval 13 the switching current 8 is set to a damping current intensity I.sub.3, which adjusts, in particular reduces, a speed of the switchover movement. This can reduce noise produced on the impact of the valve body 4 on the first stop 16. Between the third time t.sub.3 and a fourth time t.sub.4, in a fourth time interval 14, the switching current 8 is set to a second switchover current intensity I.sub.4, which ensures that a switchover of the solenoid valve 1 has taken place. After the fourth time the solenoid valve 1 is in the first position. Therefore, the first holding current intensity I.sub.A is applied. Both the second switchover current intensity I.sub.4 and the first holding current intensity I.sub.A here are equal to zero. This means that the valve or the valve body is held in the first position (only) by the restoring force and the magnet exerts no forces in the first position. The fourth time interval 14 and the fourth time t.sub.4 are nevertheless drawn here, in order to make a clear comparison with FIG. 2.
(10) Both when the solenoid valve 1 is switched over from the first position into the second position (FIG. 2) and when the solenoid valve 1 is switched from the second position to the first position (FIG. 3) a setting of the solenoid valve 1 is monitored during the fourth time interval 14. If a multiplicity of similar switching operations is carried out, in a subsequent switching process the valve body 4 can be accelerated more strongly in the second time interval 12, if in a previous switching operation a switchover of the solenoid valve 1 was not detected until the fourth time interval 14. If, on the other hand, no switching is detected in the fourth time interval 14, in a subsequent switching operation the valve body 4 can be accelerated at a lower rate in the second time interval 12.
(11) FIG. 4 shows a schematic waveform of the switching current when the solenoid valve 1 of FIG. 1 repeatedly switches over from the first position to the second position. Three switching operations are shown here, which (as indicated by dots) are not executed immediately one after another. As in FIG. 2, here the current I is plotted against the voltage t and the real switching current 21 is shown. In the switchover operation shown on the left and right the solenoid valve 1 is switched over as desired. In the middle switchover operation, on the other hand, an artefact 20 is apparent in the real switching current 21. The artefact 20 arises due to a movement of the valve body 4 (i.e. caused by the switching of the solenoid valve 1) as a result of electromagnetic induction. This artefact 20 shows that the solenoid valve 1 is only switched over due to the second switchover current intensity I.sub.4.
