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 present invention relates to a method for controlling an electromagnetically controllable gas valve as described in the preamble of claim 1. Such a gas valve is also referred to as a gas metering valve or a gas injector. The gas may be, in particular, a gaseous power fuel or a combustible fuel required to operate an internal combustion engine or a fuel cell system, for example, hydrogen.

[0002] Furthermore, the present invention relates to a control device configured to perform the steps of the proposed method.

Background Art

[0003] Background Art Gas valves for metering and supplying gaseous fuels or fuels are well known based on the prior art. Gas valves are often controlled electromagnetically. In this case, a solenoid coil is provided. This solenoid coil acts on a reciprocating solenoid armature. This solenoid armature can be connected to a valve member to open and close the gas valve or itself forms the valve member.

[0004] In gas valves, due to the lack of hydraulic damping, overly violent closing collisions easily occur. As a result of this closing collision, the amount during injection increases significantly, and significant seat wear occurs. Furthermore, the closing collision is accompanied by undesirable noise generation. Therefore, in order to operate the gas valve, robust means for damping the closing operation must be found.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention addresses this problem. In particular, it is required to reduce the collision speed when the gas valve closes, thereby achieving, on the one hand, an improvement in robustness and, on the other hand, avoiding the reopening of the gas valve based on the closing collision.

Means for Solving the Problems

[0006] To solve the problem, a method having the features of claim 1 is proposed. Advantageous improvements to the present 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, to open the seal seat, a solenoid coil acting on a solenoid armature is energized, thereby disengaging the valve member cooperating with the seal seat from the seal seat by the solenoid armature. To close the seal seat, the energization of the solenoid coil is terminated, thereby returning the valve member to the seal seat by the spring force of the closing spring, and by returning the valve member to the seal seat, the solenoid armature is separated from the valve member and performs a free stroke. According to the present invention, a braking current is supplied to the solenoid coil during closing, and the energization of the solenoid coil is interrupted and / or the current level is changed depending on the direction of motion of the solenoid armature.

[0008] The supply of a braking current slows the motion of the solenoid armature, causing it to reach the stopper at a reduced speed. This reduces or dampens the impact force against the stopper. Correspondingly, the robustness of the gas valve in the stopper region or the region of the contact surface forming the stopper is improved. Furthermore, significant closing collisions that would cause the gas valve to reopen after closing are avoided. In this regard, the free stroke of the solenoid armature relative to the valve member has also been found to be advantageous.

[0009] In the proposed method, the solenoid armature can be braked significantly more effectively than continuous energization by supplying a braking current according to the direction of motion of the solenoid armature. This is because the magnetic force provides the desired braking force when the solenoid armature is moved toward the stopper. When the direction of motion of the solenoid armature is reversed based on a closing collision after reaching the stopper, the magnetic force has the opposite effect; that is, the solenoid armature is accelerated rather than braked. The proposed method prevents interruption of energization to the solenoid coil and / or changes in current level depending on the direction of motion of the solenoid armature. As a result, the braking current is supplied in pulses.

[0010] The proposed method for supplying pulsed damping current requires recognition of the direction of motion of the solenoid armature. Therefore, in an improved embodiment of the present invention, it is proposed to perform control frequency analysis of the current signal and / or voltage signal to detect the direction of motion of the solenoid armature. This is because the direction of motion of the solenoid armature affects the control frequency. This effect is due to the fact that the inductance of the solenoid coil increases as the working air gap between the solenoid armature and the magnetic poles of the magnetic circuit decreases. As a result, the control frequency is increased. Conversely, as the working air gap increases, the induced voltage increases the current. At this stage, depending on the speed of the solenoid armature, no current control is performed at all, or current control is performed at a low control frequency.

[0011] Preferably, a braking current is supplied only when the solenoid armature is moved in the direction of the stopper and / or reversal point furthest from the seal seat, thereby resulting in a de-energization during the braking current phase. That is, the energization is interrupted at least once, and again when the solenoid armature is moved in a different direction or towards the valve member after reaching the stopper and / or reversal point. The de-energization prevents the solenoid armature from being accelerated towards the valve member, potentially disengaging the valve member from the seal seat again, thereby preventing the gas valve from opening again. If the solenoid armature changes its direction of motion multiple times based on closing collisions, ideally, the braking current phase and de-energization alternate.

[0012] Therefore, it is further proposed that when the solenoid armature reaches the stopper and / or reversal point closer to the seal seat, another damping current stage follows the de-energization.

[0013] When braking current stages and de-energization are performed alternately, it is even more preferable to select a current level in each subsequent braking current stage that is at most equal to the current level of the preceding braking current stage. This is because each time the direction of motion is reversed, the speed of the solenoid armature is also reduced, thereby reducing the braking force as well. Therefore, it is preferable to reduce the current level in each subsequent braking current stage.

[0014] As an alternative or supplement to the interruption of the braking current, the current level of the braking current may be varied according to the direction of motion of the solenoid armature. In this case, instead of a continued interruption of the braking current stage, a braking current stage continues at the varied current level, albeit in a further braking current stage. For example, depending on the direction of motion of the solenoid armature, the current level may be reduced to such an extent that the magnetic force of the solenoid coil has no effect on the motion of the solenoid armature, or only a very slight effect. This is advantageous when the solenoid armature has already reached its stopper and is to be moved again from the stopper toward the valve member. Since the magnetic force is relatively small, the solenoid armature is not accelerated, or is accelerated only very slightly, thereby preventing undesirable back-blowing.

[0015] Therefore, preferably, the current level of the braking current is reduced when the solenoid armature reaches the stopper and / or reversal point furthest from the seal seat. More preferably, the current level of the braking current is increased again when the solenoid armature reaches the stopper and / or reversal point closer to the seal seat. Subsequently, the motion of the solenoid armature, which is moved again in the direction of the stopper and / or reversal point furthest from the seal seat, is again braked by magnetic force.

[0016] Maintaining an extremely low current level when the solenoid armature is already moving toward the valve member during gas valve closure has the advantage of allowing the braking current to be used as a sensor current. In particular, this sensor current can be used to detect the direction of motion of the solenoid armature.

[0017] In the proposed method, in order to avoid impairing the dynamic characteristics of the closing operation, the braking current is supplied not at the start of the closing operation, but only towards the end of the closing operation. In any case, the braking current is supplied before the gas valve closes, that is, before the valve member is returned to the seal seat. This is because, in this case, the proposed method can simultaneously achieve recognition of the closing time.

[0018] To this end, preferably, during the initial braking current phase, the current level is continuously increased until it reaches a first target level, for example, 4A to 10A. The arrival of this first target level then initiates a coasting phase, defining a new target level for the braking current that is 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 extinguishing voltage is applied to terminate this coasting phase.

[0019] Reaching a high first target level ensures that a sufficiently high magnetic force is generated to brake the motion 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 improved. Subsequently, the coasting phase can be used for closing time recognition. In this case, the moment when the valve member returns to the seal seat, i.e., the moment when the gas valve actually closes, is detected. At the end of the injection process, the solenoid armature separates from the valve member and performs a free stroke, so the motion of the solenoid armature is not correlated with the motion of the valve member. Therefore, the armature motion cannot be used for detecting the closing time.

[0020] Preferably, the closing time of the gas valve is detected by evaluating the current transition and / or voltage transition during the coasting phase. This is possible because when the gas valve closes, the solenoid armature is separated from the valve member and is subsequently moved or performs 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 suddenly disappears. This causes a sharp change in speed. This change in speed can be recognized not only at the kink in the speed curve but also in the current signal and / or voltage signal.

[0021] By recognizing the closing time, a change can be recognized, and in some cases, the control of the gas valve can be adapted to this change. Thus, a control circuit for controlling the closing time can be realized. Therefore, the metering supply accuracy of the gas valve can be further improved by recognizing the closing time.

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

[0023] In order to solve the problems described at the beginning, a control device for controlling the gas valve is further proposed. This control device is configured to perform the steps of the method according to the present invention. In particular, the control device can supply a pulsed braking current to the solenoid coil of the gas valve. Furthermore, the control device can evaluate the current transition and / or voltage transition in order to detect the movement direction of the solenoid armature and / or the closing time of the gas valve.

[0024] Hereinafter, the present invention and its advantages will be described in detail based on the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1]Graphs of a) current transition, b) voltage transition, and c) armature stroke during the opening and closing operation of an electromagnetic controllable gas valve. [Figure 2] Graph of a) current transition and b) schematic longitudinal sectional view of a gas valve during the first stage of braking current supply. [Figure 3] Graph of a) current transition and b) schematic longitudinal sectional view of a gas valve during the second stage of braking current supply. [Figure 4] Graph of a) current transition and b) schematic longitudinal sectional view of a gas valve during the third stage of braking current supply. [Figure 5] Schematic longitudinal sectional views a) and b) of a gas valve controllable by the method according to the present invention.

Embodiments for Carrying Out the Invention

[0026] Detailed Description of the Drawings In the graph of FIG. 1, for example, a) current transition, b) voltage transition, and c) armature stroke during the opening and closing operation of an electromagnetic controllable gas valve 1 as shown in FIGS. 2 to 5 are shown. For opening, first, the solenoid coil 4 is energized. The magnetic force of the solenoid coil 4 acts on the solenoid armature 3, whereby the solenoid armature 3 is pulled in the direction of the solenoid coil 4. In this case, the solenoid armature 3 disengages the valve member 5 from the seal seat 2, whereby the gas valve 1 opens. Therefore, this gas valve 1 is formed as a normally closed valve. Closing is achieved by a closing spring 6 that applies a preload to the valve member 5 in the direction of the seal seat 2 (for example, refer to FIG. 2b).).

[0027] Therefore, to open the valve, the solenoid coil 4 is first energized. This energization includes a boost stage for initial opening, an attraction stage for further opening, and a holding stage for maintaining the open position (see Figure 1a). A decrease in the current level occurs in each stage. To close the valve, the energization of the solenoid coil 4 is terminated, causing the closing spring 6 to return the valve member 5 to the seal seat 2. In this case, the valve member 5 engages the solenoid armature 3. At time t1, the valve member 5 has returned to the seal seat 2, and from this point onward, the solenoid armature 3 continues its movement independently, with a free stroke h until it reaches the stopper 7. F This is performed. Since the acceleration due to the spring force of the closing spring 6 is eliminated, the solenoid armature 3 reduces its speed. This can be read from the current and / or voltage changes, and based on these current and / or voltage changes, the closing time t1 of the gas valve 1 can be detected.

[0028] At time t2, reaching stopper 7 causes a so-called closing collision, reversing the direction of motion of the solenoid armature 3. That is, the solenoid armature 3 is moved again towards valve member 5, which poses a risk of the gas valve 1 opening again. In this case, valve member 5 forms a further stopper 8 for the solenoid armature 3. As a result, the direction of motion of the solenoid armature 3 is reversed again, and the solenoid armature 3 is moved again towards stopper 7. In Figure 1c), the direction of motion of the solenoid armature 3 is reversed at times t2 to t6, respectively. This change in direction of motion can also be read in the current signal and / or voltage signal, and by analyzing the control frequency, the armature motion can be detected. This is because, as is clear from the voltage transition in Figure 1b), the control frequency is changed according to the direction of motion of the solenoid armature 3.

[0029] Recognizing the direction of motion of the solenoid armature 3 enables control of the gas valve 1 by the method according to the present invention. The method according to the present invention will be explained below illustratively with reference to Figures 2 to 4.

[0030] Figure 2b) first illustrates a gas valve 1 suitable for carrying out the method. This gas valve 1 includes a solenoid coil 4 for acting on a solenoid armature 3 that can be connected to a valve member 5. The valve member 5 is preloaded in the direction of the seal seat 2 by a closing spring 6.

[0031] Figure 2a) shows the current transition during the opening and closing operation of the gas valve 1 shown in Figure 2b). During closing, after a period of de-energization, a braking current stage A, including a coasting phase, begins. Closing the gas valve 1 separates the solenoid armature 3 from the valve member 5, and it continues its movement independently, subsequently reaching the stopper 7 at time t2. The braking current supply is interrupted upon reaching the stopper 7, which can be detected based on the current transition. Therefore, a period of de-energization B follows the braking current stage A. This is illustrated in the same gas valve 1 shown in Figures 3a) and 3b). This is because, upon reaching the stopper 7, the solenoid armature 3 reverses its direction of motion and is then moved toward the valve member 5 (see Figure 3b). This valve member 5 forms a further stopper 8, which reverses the direction of motion again, causing the solenoid armature 3 to move toward the first stopper 7 once more. At this stage, in order to brake the movement of the solenoid armature 3 again, the energization pause B is followed by another braking current stage A, as illustrated in Figures 4a) and 4b). In the further braking current stage A, since the solenoid armature 3 is already moving sufficiently slowly, the current level can be reduced compared to the first braking current stage A. Depending on the movement of the solenoid armature 3, the stages may be repeated at any frequency.

[0032] The gas valves 1 shown in Figures 2 to 4 are merely illustrative examples. The method according to the present invention can also be implemented 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 stopper 8. That is, when the gas valve 1 is opened, the solenoid armature 3 is already in contact with the valve member 5, and there is no need to perform a free stroke 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 stopper 7.

Claims

1. A method for controlling an electromagnetically controllable gas valve (1), In order to open the seal seat (2), current is supplied to the solenoid coil (4) acting on the solenoid armature (3), thereby causing the valve member (5) which cooperates with the seal seat (2) to be detached from the seal seat (2) by the solenoid armature (3). In order to close the seal seat (2), the current to the solenoid coil (4) is cut off, thereby returning the valve member (5) to the seal seat (2) by the spring force of the closing spring (6). In a method in which the valve member (5) is returned to the seal seat (2), thereby separating the solenoid armature (3) from the valve member (5) and performing a free stroke, During the closing period, a braking current is supplied to the solenoid coil (4), and the energization to the solenoid coil (4) is interrupted and / or the current level is changed according to the direction of motion of the solenoid armature (3). To detect the direction of motion of the solenoid armature (3), control frequency analysis of the current signal and / or voltage signal is performed. A method characterized by the following features.

2. The solenoid armature (3) is supplied with a braking current only when it is moved in the direction of the stopper (7) and / or the reversal point that is farther from the seal seat, and thereby the energization is suspended (B) during the braking current stage (A). The method according to claim 1.

3. The solenoid armature (3) is characterized in that when it reaches the stopper (8) and / or reversal point closer to the seal seat, the de-energization (B) is followed by another braking current stage (A). The method according to claim 2.

4. The braking current stage (A) and the de-energizing stage (B) are performed alternately, and preferably, in each subsequent braking current stage (A), a current level is selected that is at most equal to the current level of the preceding braking current stage. The method according to claim 3.

5. The current level of the braking current is reduced when the solenoid armature (3) reaches the stopper (7) and / or reversal point furthest from the seal seat. The method according to claim 1.

6. When the solenoid armature (3) reaches the stopper (8) and / or reversal point closer to the seal seat, the current level of the braking current is increased again, and preferably, a sensor current is used to detect the direction of motion of the solenoid armature (3), characterized in that The method according to claim 5.

7. During the initial braking current phase, the current level is continuously increased until it reaches a first target level; upon reaching the first target level, a coasting phase is initiated in which a new target level for the braking current that is at most equal to the first target level is defined; and the coasting phase is terminated when the solenoid armature (3) reverses its direction of motion, preferably by applying an extinguishing voltage to terminate the coasting phase. The method according to claim 1.

8. The method is characterized by detecting the closing time of the gas valve (1) by evaluating the current and / or voltage changes during the coasting stage. The method according to claim 7.

9. A control device for controlling a gas valve (1), configured to carry out the steps of the method according to claim 1.

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