METHOD FOR CONTROLLING A VEHICLE SEAT VALVE

Abstract

A method for controlling a vehicle seat valve, the piston thereof is actively displaced from a closed position into an open position or vice versa by an electrical voltage being applied to an electromagnetic drive means. The power of the drive means is regulated via an effective voltage which can be changed by means of pulse width modulation of an impulse voltage that has a constant frequency. In order to displace the piston from its closed position toward its open position, a duty cycle of the pulse width modulation is firstly increased from a rest duty cycle to a starting duty cycle of less than 100%, and the duty cycle is only raised to a final duty cycle when the piston has reached the open position and/or if a blockage impeding the displacement of the piston before it reaches its open position is identified.

Claims

1. A method for controlling a vehicle seat valve, the piston of which is actively displaced from a closed position into an open position or vice versa by an electrical voltage being applied to an in particular electromagnetic drive means, wherein the power of the drive means is regulated via an effective voltage which can be changed by means of pulse width modulation of an impulse voltage that has a constant frequency, a duty cycle (D) of the pulse width modulation firstly being increased from a rest duty cycle (D1), in particular 0%, to a starting duty cycle (D) of less than 100%, in particular of less than 50%, in order to displace the piston from its closed position toward its open position, and the duty cycle only being raised to a final duty cycle (D4), in particular to 100%, when the piston has reached the open position and/or if a blockage impeding the displacement of the piston before it reaches its open position is identified.

2. The method according to claim 1, wherein the starting duty cycle (D2), in particular before or after the piston has reached the open position, is firstly raised linearly within a first time period (T1) to an intermediate duty cycle (D3) that is smaller than the final duty cycle (D4).

3. The method according to claim 2, wherein the intermediate duty cycle (D3), before or after the piston has reached the open position, is raised linearly to the final duty cycle (D4) within a second time period (T2) that is in particular shorter than the first time period (T1).

4. The method according to claim 1, wherein the final duty cycle (D4) being lowered, in particular abruptly, to a holding duty cycle (D5) after the piston has reached the open position, such that the piston loaded with a restoring force in particular resulting from a mechanical spring means is held in its open position by a drive force of the drive means that counteracts said restoring force.

5. The method according to claim 1, wherein a fluid pressure of a fluid flow which can be switched by the vehicle seat valve is detected, a blockage impeding the displacement of the piston toward its open position being identified on the basis of the absence of an expected change in the fluid pressure during the manipulation of the drive means.

6. The method according to claim 4, wherein the piston is displaced from its closed position toward its open position counter to a restoring force that in particular results from a mechanical spring means, the holding duty cycle (D5) being lowered, at the beginning of the displacement of the piston from its open position back toward its closed position, until a drive force of the drive means that acts on the piston is smaller than the restoring force that loads the piston in the opposite direction.

7. The method according to claim 4, wherein a fluid pressure that increases the restoring force loading the piston is detected during the displacement of the piston back toward its closed position, the holding duty cycle (D5) being lowered until a drive force of the drive means that acts on the piston is smaller than the restoring force that loads the piston in the opposite direction and is increased by the fluid pressure.

8. The method according to claim 4, wherein the holding duty cycle (D5) being lowered linearly to the rest duty cycle (D1) in particular during the displacement of the piston back toward its closed position or after the piston has reached the closed position, such that the rest duty cycle (D1) is only reached as soon as or after the piston is in its closed position.

9. A controller for at least one vehicle seat valve, for carrying out the method according to claim 1.

10. A vehicle seat comprising at least one vehicle seat valve and a controller according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following, the present invention will be explained in greater detail with reference to an embodiment shown schematically. In the drawings:

[0028] FIG. 1 shows a schematic sequence of the method according to the invention for displacing the piston of a vehicle seat valve into its open position; and

[0029] FIG. 2 shows a schematic sequence of the method according to the invention for displacing the piston of a vehicle seat valve into its closed position.

DETAILED DESCRIPTOIN OF PREFERRED EMBODIMENTS

[0030] FIG. 1 shows a purely schematic sequence of the method according to the invention for displacing a piston of a vehicle seat valve (not shown in greater detail). In this case, the control of the vehicle seat valve is shown merely by means of a first function graph 1a, from which control an effective voltage applied to a drive means manipulating the piston is produced. The drive means is preferably an electromagnetic drive means.

[0031] The method according to the invention is based on an impulse voltage having a constant frequency, by means of the pulse width modulation (PWM) of which a correspondingly variable effective voltage can be applied to the drive means. By changing the effective voltage, the power of the drive means that actively displaces the piston into its closed position can be correspondingly regulated. For this purpose, a duty cycle D of the pulse width modulation is changed in the following manner:

[0032] At the beginning of the displacement of the piston, said piston is in its closed position. In the closed position, the piston is loaded and thus held by a spring means which is for example mechanical. In the closed position, the rest duty cycle D1 is 0%, so that an effective voltage applied to the drive means of 0.0 volts (V) is produced. Purely by way of example, in order to then displace the piston from its closed position toward its open position, the rest duty cycle D1 is abruptly increased to a starting duty cycle D2 after a time t of 20 milliseconds (ms). Purely by way of example, the starting duty cycle D2 is now 30%, and therefore almost 30% of the impulse voltage is now applied to the drive means as the effective voltage.

[0033] The starting duty cycle D2 is in principle selected such that, in normal operation, the piston moves from its closed position toward its open position counter to the restoring force loading it. The starting duty cycle D1 can already be sufficient for displacing the piston as far as into its open position, which it only reaches at a slow speed and force as a result of the reduced power of the drive means. As a result, in particular the abutment against the structural movement boundary of said piston is correspondingly gentle, so that resulting noise emissions are reduced to a minimum.

[0034] In order to overcome any possible movement blockages of the piston, the starting duty cycle D2 is raised to an intermediate duty cycle D3 over a first time period T1 of—in this case purely by way of example—60 ms. Purely by way of example, the intermediate duty cycle D3 is now 60%, and therefore almost 60% of the impulse voltage is now applied to the drive means as the effective voltage. The linear raise to the intermediate duty cycle D3 is advantageous in that, in the event of a possible movement blockage of the piston, the simultaneously increasing drive force of the drive means eventually reaches a level which could be sufficient for overcoming the movement blockage and thus displaces the piston into its open position. At the same time, only part of the maximum possible impulse voltage is applied to the drive means as the effective voltage, and therefore noise emissions which are possibly higher but still very low can result in this case, too.

[0035] If there is no movement blockage present, the piston, which is already in its open position as a result of the starting duty cycle D2, is merely pushed further against its structural movement boundary by this measure, as a result of which no noise develops. In this respect, raising the starting duty cycle D2 to the intermediate duty cycle D3 is understood to be a protective measure for ensuring that the piston does not remain in its closed position due to a movement blockage.

[0036] In order to overcome an even larger movement blockage of the piston that is still in its closed position or has become stuck on the way toward its open position, the intermediate duty cycle D3 is now raised to a final duty cycle D4 over a second time period T2 of—in this case purely by way of example—20 ms. As can be seen, the second time period T2 is significantly shorter than the first time period T1, and therefore, in combination with raising the duty cycle D by a further 40%, this produces a significantly steeper curve of the function graph 1a during the second time period T2.

[0037] Purely by way of example, the final duty cycle D4 is now 100%, and therefore almost 100% of the impulse voltage is now applied to the drive means as the effective voltage. The linear raise to the final duty cycle D4 is advantageous in that, in the event of a possible movement blockage of the piston, the simultaneously increasing drive force of the drive means eventually reaches a level which could be sufficient for overcoming the movement blockage and thus finally displaces the piston into its open position. A movement blockage that is potentially present in the region of the open position of the piston can also be overcome hereby, in order to finally displace said piston into its open position. In such a scenario outside of normal operation, the speed and force of the piston, produced as a result of the now significantly higher drive power of the drive means, can be accompanied by correspondingly greater noise emissions, but nevertheless it is ensured that the piston is in any case displaced into its open position.

[0038] With the measures taken previously, it can be assumed that the piston is now definitively in its open position. In a next step, the final duty cycle D4 is now abruptly lowered to a holding duty cycle D5. Purely by way of example, this is now 40%, and therefore 40% of the impulse voltage is now applied also to the drive means as the effective voltage.

[0039] The holding duty cycle D5 is selected such that the piston is in any case securely held in its open position and the vehicle seat valve fulfills the function assigned thereto.

[0040] In principle, a fluid pressure of a fluid flow which can be switched by the vehicle seat valve, which fluid pressure acts on the piston, can be detected. If the duty cycle D is manipulated in order to induce the displacement of the piston from its closed position, but no expected change in the fluid pressure is identified, the first time period T1 can be shortened, for example, and/or the intermediate duty cycle D3 can be greater than the value set out here, for example, in order for the clearly present movement blockage of the piston to be overcome as quickly as possible.

[0041] FIG. 2 also shows, in a purely schematic manner by means of a second function graph 1b, the sequence of the method according to the invention for displacing the piston back into its closed position. As can be seen, the holding duty cycle D5 is initially 40%, for example, in the open position of the piston. Proceeding from this, after 20 ms, the holding duty cycle D5 is lowered, purely by way of example, to the initial rest duty cycle D1 of 0% over a third time period T3. Purely by way of example, the third time period T3 is in this case 60 ms.

[0042] As a result of loading the piston with the restoring force, at some point during the lowering of the holding duty cycle D5 a point in time is reached at which the restoring force is greater than the current duty cycle D, so that the piston is displaced gently back into its closed position by the restoring force. The third time period T3 is selected such that, under normal circumstances, the rest duty cycle D1 is only achieved as soon as or after the piston has arrived in its closed position. In so doing, the speed and force of the moving piston are also reduced to a minimum, thereby achieving a significant reduction in noise.

[0043] A fluid pressure that increases the restoring force loading the piston can self-evidently also be detected during the displacement of the piston back toward its closed position and be taken into account when lowering the holding duty cycle D5. This consideration can be expressed, for example, in a corresponding adjustment of the third time period T3.

LIST OF REFERENCE SIGNS:

[0044] 1a first function graph [0045] 1b second function graph [0046] D duty cycle of the pulse width modulation in percent [%] [0047] D1 rest duty cycle [0048] D2 starting duty cycle [0049] D3 intermediate duty cycle [0050] D4 final duty cycle [0051] D5 holding duty cycle [0052] t time in milliseconds [ms] [0053] T1 first time period between D2 and D3 [0054] T2 second time period between D3 and D5 [0055] T3 third time period between D5 and D1