Method and control device for controlling an electromagnetically controllable gas valve

Abstract

The invention relates to a method for controlling an electromagnetically controllable gas valve (1), in which, in order to open a sealing seat (2), a solenoid coil (4) acting on a solenoid armature (3) is energized, whereby a valve member (5) cooperating with said sealing seat (2) is disengaged from said sealing seat (2) by the solenoid armature (3), and in order to close said sealing seat (2), the solenoid coil (4) is de-energized, whereby the valve member (5) returns to said sealing seat (2) by the spring force of a closing spring (6), whereby the solenoid armature (3) is separated from the valve member (5) and performs a free stroke. According to the invention, during closing, a braking current is supplied to the solenoid coil (4) and, depending on the direction of movement of the solenoid armature (3), the energization of the solenoid coil (5) is interrupted and / or the current magnitude is changed. The invention further relates to a control device for carrying out the steps of the method.

Description

[Technical field]

[0001] The invention relates to a method for controlling an electromagnetically controllable gas valve, also called a gas metering valve or a gas injector, according to the preamble of claim 1. The gas may in particular be a gaseous power fuel or a combustible fuel, for example hydrogen, which is required for operating an internal combustion engine or a fuel cell system.

[0002] Furthermore, the invention relates to a control device adapted to carry out the steps of the proposed method. [Background technology]

[0003] Background technology Gas valves for metering gaseous fuels or fuels are well known from the prior art. Gas valves are often controlled electromagnetically. In this case, a solenoid coil is provided which acts on a reciprocable solenoid armature which can be connected to a valve member for opening and closing the gas valve or which itself forms the valve member.

[0004] Due to the lack of hydraulic damping, excessively violent closing collisions easily occur in gas valves. These closing collisions result in a large increase in the injection volume and considerable seat wear. Furthermore, the closing collisions are accompanied by undesirable noise emissions. Therefore, robust means for damping the closing movement must be found in order to operate the gas valves. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention addresses this problem, and in particular it is desired to reduce the impact velocity during closing of the gas valve, thereby, on the one hand, achieving improved robustness and, on the other hand, avoiding reopening of the gas valve due to the closing impact. [Means for solving the problem]

[0006] To achieve this goal, a method is proposed having the features of claim 1. Advantageous refinements of the invention can be found in the dependent claims. Furthermore, a control device for carrying out the steps of the method is described.

[0007] Disclosure of the Invention In the proposed method for controlling an electromagnetically controllable gas valve, in order to open the sealing seat, a solenoid coil acting on the solenoid armature is energized, whereby the valve member cooperating with the sealing seat is disengaged from the sealing seat by the solenoid armature. In order to close this sealing seat, the solenoid coil is de-energized, whereby the valve member returns to the sealing seat by the spring force of the closing spring, by which the solenoid armature is separated from the valve member and performs a free stroke. According to the invention, during closing, a braking current is supplied to the solenoid coil, which is interrupted and / or the current magnitude is changed depending on the direction of movement of the solenoid armature.

[0008] By applying a braking current, the movement of the solenoid armature is braked, so that the solenoid armature reaches its stop at a reduced speed. This reduces or damps the impact shock on the stop. Correspondingly, the robustness of the gas valve in the area of ​​the stop or in the area of ​​the contact surface forming the stop is increased. Furthermore, significant closing impacts that reopen the gas valve after closing are avoided. In this connection, the free stroke of the solenoid armature relative to the valve member has also proven to be advantageous.

[0009] In the proposed method, the braking current is supplied depending on the direction of movement of the solenoid armature, so that the solenoid armature can be braked significantly more effectively than with continuous current supply, because the magnetic force produces the targeted braking action when the solenoid armature is moved towards the stop. When the direction of movement of the solenoid armature is reversed due to a closing collision after reaching the stop, the magnetic force has the opposite effect, i.e. the solenoid armature is accelerated instead of braked. The proposed method makes it possible to prevent interrupting the current supply to the solenoid coil and / or changing the current magnitude depending on the direction of movement of the solenoid armature. As a result, the braking current is supplied in pulses.

[0010] The pulsed braking current supply according to the proposed method requires knowledge of the direction of movement of the solenoid armature. In a refinement of the invention, it is therefore proposed to carry out a control frequency analysis of the current and / or voltage signals in order to detect the direction of movement of the solenoid armature, since the direction of movement of the solenoid armature influences the control frequency. This influence is due to the fact that the smaller the working air gap between the solenoid armature and the pole bodies of the magnetic circuit, the greater the inductance of the solenoid coil. As a result, the control frequency is increased. On the other hand, with a larger working air gap, the induced voltage increases the current. At this stage, depending on the speed of the solenoid armature, there is no current control at all or a current control with a low control frequency.

[0011] Preferably, the braking current is only supplied when the solenoid armature is moved in the direction of the stop and / or reversal point away from the sealing seat, so that the braking current phase is followed by a de-energization, i.e. the current is interrupted at least once and when the solenoid armature is moved in another direction or in the direction of the valve member after reaching the stop and / or reversal point. The de-energization prevents the solenoid armature from accelerating in the direction of the valve member, possibly causing this valve member to leave the sealing seat again, thereby preventing the gas valve from opening again. If the solenoid armature changes its direction of movement many times due to a closing collision, ideally the braking current phase and the de-energization alternate.

[0012] It is therefore further proposed that the de-energisation is followed by another braking current phase when the solenoid armature reaches the stop close to the sealing seat and / or the reversal point.

[0013] If braking current phases and de-energizations are alternated, then preferably a current level is selected in each subsequent braking current phase that is at most as high as the current level of the preceding braking current phase, since with each subsequent reversal of the direction of motion the speed of the solenoid armature is also reduced, which makes the braking action likewise smaller.Preferably therefore, in each subsequent braking current phase the current level is reduced.

[0014] Alternatively or additionally to the interruption of the braking current, the current level of the braking current can be changed depending on the direction of movement of the solenoid armature. In this case, the braking current phase is not followed by a deenergization, but by a further braking current phase, but at a changed current level. For example, depending on the direction of movement of the solenoid armature, the current level can be reduced to such an extent that the magnetic force of the solenoid coil has no or only a very small effect on the movement of the solenoid armature. This is advantageous when the solenoid armature has already reached its stop and is to be moved from the stop back towards the valve member. Since the magnetic force is correspondingly small, the solenoid armature is not accelerated or is accelerated only slightly, so that undesirable back-blow does not occur.

[0015] Therefore, preferably, when the solenoid armature reaches the stopper and / or reversal point farther from the seal seat, the current magnitude of the braking current is decreased. More preferably, when the solenoid armature reaches the stopper and / or reversal point closer to the seal seat, the current magnitude of the braking current is increased again. Thereafter, the movement of the solenoid armature, which is again moved in the direction of the stopper and / or reversal point farther from the seal seat, is braked again by the magnetic force.

[0016] The maintenance of a very low current level already at the stage when the solenoid armature is moved in the direction of the valve member when the gas valve is closed has the advantage that the braking current can be used as a sensor current, in particular by means of which the direction of movement of the solenoid armature can be detected.

[0017] In the proposed method, in order not to impair the dynamics of the closing operation, the braking current is not supplied at the beginning of the closing operation, but only towards the end of the closing operation. In any case, the braking current is supplied before the closing of the gas valve, i.e. before the valve member is returned to its sealing seat, because in this case, the proposed method allows the closing time recognition to be realized at the same time.

[0018] For this purpose, preferably during an initial braking current phase, the current height is continuously increased until a first target level is reached, for example between 4 A and 10 A. Reaching this first target level then initiates a coasting phase, which defines a new target level for the braking current at most equal to this first target level. The coasting phase is terminated when the solenoid armature reverses its direction of motion, and preferably an erase voltage is applied to terminate this coasting phase.

[0019] Reaching the high first target level ensures that a sufficiently high magnetic force is generated to brake the movement of the solenoid armature. This reduces the risk of a closing collision. At the same time, the robustness and metering accuracy of the gas valve are increased. The subsequent coasting phase can then be used for closing time recognition. In this case, the time when the valve member is returned to its sealing seat, i.e. when the gas valve is actually closed, is detected. Since at the end of the blowing process the solenoid armature is separated from the valve member and performs a free stroke, the movement of the solenoid armature does not correlate with the movement of the valve member. The armature movement cannot therefore be used for closing time detection.

[0020] The time of closing of the gas valve is preferably detected by evaluating the current and / or voltage curves during the coasting phase. This is possible because, by closing the gas valve, the solenoid armature is separated from the valve member and is allowed to continue moving or perform a free stroke. As soon as the solenoid armature is separated from the valve member, the acceleration of the solenoid armature caused by the spring force of the closing spring is abruptly eliminated. This causes a sharp speed change. This speed change can not only be recognized in a knee in the speed curve, but can also be read off in the current and / or voltage signal.

[0021] By knowing the closing time, changes can be recognized and, if necessary, the control of the gas valve can be adapted to these changes. In this way, a control circuit for controlling the closing time can be realized. The metering accuracy of the gas valve can therefore be further improved by knowing the closing time.

[0022] As voltage source for the braking current to be supplied, a boost voltage or a battery voltage may be used, for example in mobile applications the battery voltage of the vehicle battery may be used.

[0023] In order to achieve the object mentioned at the beginning, a control device for controlling a gas valve is further proposed, which is designed to carry out the steps of the method according to the invention. In particular, the control device can supply a pulsed braking current to a solenoid coil of the gas valve. Furthermore, the control device can evaluate the current and / or voltage curves in order to determine the direction of movement of the solenoid armature and / or the time point of closing of the gas valve.

[0024] The invention and its advantages are explained in more detail below on the basis of the accompanying drawings. [Brief description of the drawings]

[0025] [Figure 1]2 is a graph of a) the current profile, b) the voltage profile and c) the armature stroke during the opening and closing operation of an electromagnetically controllable gas valve. [Diagram 2] 4A) Graph of the current course during a first phase of braking current supply and b) schematic longitudinal section of the gas valve. FIG. [Diagram 3] 4A) A graph of the current course during a second phase of the braking current supply and b) a schematic longitudinal section of the gas valve. [Figure 4] 6A) A graph of the current course during a third phase of the braking current supply and b) a schematic longitudinal section of the gas valve. [Diagram 5] 1A and 1B are schematic longitudinal cross-sectional views of a gas valve which can be controlled by the method according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Detailed Description of the Drawings The graph in FIG. 1 shows a) the current course, b) the voltage course and c) the armature stroke during the opening and closing operation of an electromagnetically controllable gas valve 1, for example as shown in FIGS. 2 to 5. For opening, the solenoid coil 4 is first energized. The magnetic force of the solenoid coil 4 acts on the solenoid armature 3, which is pulled in the direction of the solenoid coil 4. The solenoid armature 3 then disengages the valve member 5 from the sealing seat 2, whereby the gas valve 1 is opened. The gas valve 1 is therefore configured as a normally closed valve. Closing is achieved by a closing spring 6, which preloads the valve member 5 in the direction of the sealing seat 2 (see for example FIG. 2b).

[0027] Thus, for opening, first the solenoid coil 4 is energized. This energization includes a boost phase for initial opening, a suction phase for further opening and a hold phase for holding the valve open (see FIG. 1a). In each phase, a reduction in the current level occurs. For closing, the solenoid coil 4 is de-energized, so that the closing spring 6 returns the valve member 5 to the sealing seat 2. The valve member 5 then engages the solenoid armature 3. At the time t1, the valve member 5 has been returned to the sealing seat 2, so that from this point onwards the solenoid armature 3 continues its movement alone, with a free stroke h until it reaches the stop 7. F Since there is no longer any acceleration due to the spring force of the closing spring 6, the solenoid armature 3 slows down, which can be read off in the current and / or voltage curves, so that the closing time t1 of the gas valve 1 can be determined on the basis of these current and / or voltage curves.

[0028] Reaching the stop 7 at time t2 results in a so-called closing collision, which causes the solenoid armature 3 to reverse its direction of movement, i.e. the solenoid armature 3 is again moved towards the valve member 5, with the risk of the gas valve 1 opening again. In this case, the valve member 5 forms a further stop 8 for the solenoid armature 3. As a result, the direction of movement of the solenoid armature 3 is reversed again, and the solenoid armature 3 is again moved towards the stop 7. In FIG. 1c), a reversal of the direction of movement of the solenoid armature 3 takes place at each of the times t2 to t6. This change in the direction of movement can again be read in the current signal and / or voltage signal, so that the armature movement can be detected by analyzing the control frequency. Because, as is clear from the voltage curve in FIG. 1b), the control frequency is changed depending on the direction of movement of the solenoid armature 3.

[0029] Knowledge of the direction of movement of the solenoid armature 3 makes it possible to control the gas valve 1 by the method according to the invention.The method according to the invention is explained below by way of example on the basis of FIGS.

[0030] In Fig. 2b) firstly a gas valve 1 suitable for carrying out the method is illustrated. This gas valve 1 comprises a solenoid coil 4 acting on a solenoid armature 3 which is connectable to a valve member 5. The valve member 5 is preloaded in the direction of the sealing seat 2 by a closing spring 6.

[0031] In FIG. 2a) the current course during the opening and closing operation of the gas valve 1 of FIG. 2b) is shown. During closing, after a deenergization, a braking current phase A, which includes a coasting phase, is started. Closing of the gas valve 1 separates the solenoid armature 3 from the valve member 5, continues its movement independently and then reaches the stop 7 at time t2. Reaching the stop 7, which can be detected based on the current course, interrupts the braking current supply. The braking current phase A is therefore followed by a deenergization B. This is illustrated for the same gas valve 1 shown in FIGS. 3a) and 3b), because reaching the stop 7 causes the solenoid armature 3 to reverse its direction of movement and is then moved towards the valve member 5 (see FIG. 3b). This valve member 5 forms a further stop 8, which causes a second reversal of the direction of movement and causes the solenoid armature 3 to be moved again towards the first stop 7. In order to brake again the movement of the solenoid armature 3 in this phase, the current interruption B is followed by another braking current phase A as illustrated in figures 4a) and 4b). In the further braking current phase A, the solenoid armature 3 is already moved sufficiently slowly so that the current intensity can be reduced compared to the first braking current phase A. Depending on the movement of the solenoid armature 3, the phases may be repeated as frequently as desired.

[0032] The gas valve 1 shown in Figures 2 to 4 has been selected merely by way of example. The method according to the invention can also be carried out with other gas valves 1. An example can be seen in Figures 5a) and 5b). In Figure 5a), the gas valve 1 has an additional armature spring 9. The spring force of this armature spring 9 preloads the solenoid armature 3 in the direction of the valve member 5 or the lower stop 8. This means that when the gas valve 1 is opened, the solenoid armature 3 is already in contact with the valve member 5 and no free stroke has to be carried out first. In Figure 5b), the gas valve 1 also has an additional armature spring 9. However, this armature spring 9 preloads the solenoid armature 3 in the direction of the upper stop 7.

Claims

1. A method for controlling an electromagnetically controllable gas valve (1), comprising: To open the sealing seat (2), a solenoid coil (4) acting on a solenoid armature (3) is energized, whereby a valve member (5) cooperating with the sealing seat (2) is disengaged from the sealing seat (2) by the solenoid armature (3); In order to close the sealing seat (2), the power supply to the solenoid coil (4) is terminated, whereby the valve member (5) is returned to the sealing seat (2) by the spring force of the closing spring (6); By returning the valve member (5) to the sealing seat (2), the solenoid armature (3) is separated from the valve member (5) to perform a free stroke, 2. A method according to claim 1, further comprising: applying a braking current to said solenoid coil (4) during said closing, and interrupting and / or varying the current magnitude to said solenoid coil (5) depending on the direction of movement of said solenoid armature (3).

2. characterised in that a controlled frequency analysis of current and / or voltage signals is carried out to detect the direction of movement of the solenoid armature (3), The method of claim 1.

3. 2. A method for supplying a braking current to a solenoid armature (3) only when the solenoid armature (3) is moved in the direction of the stop (7) remote from the sealing seat and / or the reversal point, whereby a braking current phase (A) is followed by a de-energization phase (B). The method according to claim 1 or 2.

4. characterised in that the deenergisation phase (B) is followed by another braking current phase (A) when the solenoid armature (3) reaches the stop (8) close to the sealing seat and / or the reversal point. The method according to claim 3.

5. said braking current phases (A) and said current interruptions (B) are alternated, preferably by selecting in each subsequent braking current phase (A) a current level at most equal to the current level of the preceding braking current phase, The method according to claim 3 or 4.

6. the current intensity of the braking current is reduced when the solenoid armature (3) reaches a stop (7) farther from the sealing seat and / or a reversal point. The method according to claim 1 or 2.

7. characterised in that when the solenoid armature (3) reaches the stop (8) close to the sealing seat and / or the reversal point, the current intensity of the braking current is increased again, preferably using a sensor current to detect the direction of movement of the solenoid armature (3). The method according to claim 6.

8. characterised in that during an initial braking current phase, the current height is continuously increased until a first target level is reached, the reaching of which initiates a coasting phase defining a new target level for the braking current at most equal to the first target level, and that the coasting phase is terminated when the solenoid armature (3) reverses its direction of movement, preferably by applying an erasing voltage in order to terminate the coasting phase.

8. The method according to any one of claims 1 to 7.

9. the closing time of the gas valve (1) is detected by evaluating the current and / or voltage course during the coasting phase. The method according to claim 8.

10. A control device for controlling a gas valve (1), the control device being configured to carry out the steps of the method according to any one of claims 1 to 9.

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