Method for operating gas injector
By controlling the current of the electromagnetic actuator during the emission function of the gas injector, and increasing the actuator force to keep the gas injector open, the problems of gas leakage and large installation space occupation are solved, and the effect of saving space and reducing costs is achieved.
Patent Information
- Application Number
- CN202380066160.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-14
- Filing Date
- 2023-06-29
- Publication Date
- 2025-04-25
AI Technical Summary
Before the internal combustion engine is shut down, gas leaks may occur when the gas injector is running in the emission function, and the existing electromagnetic actuator design causes large installation space to take up.
By manipulating the current of the electromagnetic actuator during the discharge function, the actuator force is increased to keep the gas injector open, including continuously increasing the current until the end of the lifting phase and maintaining a constant current during the pull-in phase to compensate for the drop in gas pressure.
It realizes that the gas injector can be effectively opened under low system pressure, avoid leakage, save installation space and reduce manufacturing costs.
Smart Images
Figure CN119895134A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for operating a gas injector of an internal combustion engine in a discharge function before the engine is shut down. Background Art
[0002] Gas injectors are known from the prior art in different configurations. The problem in gas injectors that blow gaseous fuel is that, when the internal combustion engine is stopped, the gaseous fuel that is still under high pressure in the gas injector may leak despite the gas injector being closed. However, for environmental protection reasons, the above situation must be avoided. Therefore, before the internal combustion engine is finally stopped, the gas injector operates in a discharge function (so-called "purge function"), in which the gas that is still under high pressure is discharged from the gas injector into the combustion chamber of the internal combustion engine and burned there before the internal combustion engine is finally stopped. Here, the connection between the gas injector and the gas storage has been disconnected by an additional closing element. Due to the pressure drop in the gas injector during this discharge function, the gas injector must be designed so that it will also open when the system pressure is low. Here, the magnetic circuit of the electromagnetic actuator of the gas injector has been designed so that there is sufficient magnetic force even in the case of the minimum system pressure to be achieved. However, this leads to a large electromagnetic actuator, which occupies a large installation space, which is larger than the installation space required for the actual injector operation. Summary of the invention
[0003] In comparison, the method according to the invention for operating a gas injector of an internal combustion engine in the case of an exhaust function before the internal combustion engine is stopped, which has the following advantages: the electromagnetic actuator for the gas injector can be designed to be significantly smaller. As a result, installation space at the gas injector is saved, which is particularly advantageous in gas injectors that are directly blown, because there is less installation space available for the gas injector near the combustion chamber of the internal combustion engine. In addition, due to the reduced electromagnetic actuator, the gas injector can be manufactured more cost-effectively. According to the invention, this is achieved in the following way: in the case of an exhaust function, before the internal combustion engine is finally stopped, the gaseous fuel is discharged from the gas injector into the combustion chamber so that the gaseous fuel continues to be burned in the internal combustion engine. In the case of this exhaust function, in a first step, the electromagnetic actuator is controlled in the lifting phase so that the current for the electromagnetic actuator is continuously increased until the end of the lifting phase. In another step, in the pull-in phase following the lifting phase, the current for the electromagnetic actuator is kept constant. Here, the constant maintenance of the current is performed at a level corresponding to the maximum current intensity in the lifting phase. As a result, despite the reduced gas pressure in the gas injector, the gas injector can still be opened during the venting function of the gas injector and remain open because the increased actuator force compensates for the reduced gas pressure during the venting function of the gas injector.
[0004] Thus, in the case of a venting function, the current level can be increased in the pull-in phase in order to compensate for the continuously falling gas pressure in the case of a venting function.
[0005] The dependent claims reveal preferred developments of the invention.
[0006] Preferably, the increased current demand in the pull-in phase is provided by a DC-DC converter and / or a boost capacitor. In this case, the boost voltage is preferably used for control in the pull-in current phase. The boost capacitor is already charged during normal operation of the internal combustion engine and can therefore provide the increased current demand in the case of an emission function.
[0007] It is further preferred that the duration of the pull-in phase is shortened compared to the normal operation of the gas injector, i.e. the normal blowing operation. The background is that a longer pull-in current phase is caused by a higher pull-in current level. Preferably, the switching time point from the pull-in current to the holding current is stored as a constant value in the controller. Therefore, a longer pull-in current phase leads to a shorter pull-in current phase.
[0008] Further preferably, the current level in the ramp-up phase is increased compared to normal operation of the gas injector. Thus, at the end of the ramp-up phase, a higher current level is reached compared to normal operation of the gas injector, whereby the current level in the pull-in phase can also be kept at a higher level compared to normal operation in a simple manner.
[0009] Alternatively, the current level in the boost phase remains the same compared to normal operation of the gas injector.A higher current level in the pull-in phase is then provided, for example, by utilizing a boost capacitor.
[0010] Further preferably, the duration of the ramp-up phase is extended in the case of the venting function compared to normal operation of the gas injector. Thus, more time is available in the ramp-up phase to reach a higher absolute current level than in normal operation.
[0011] In order to be able to inject as much gaseous fuel as possible into the combustion chamber during the exhaust function of the gas injector, a holding phase of the gas injector, in which the gas injector remains open, is preferably prolonged compared to normal operation of the gas injector.
[0012] The invention further relates to a control unit which is configured to carry out the steps of the method according to the invention. Preferably, the control unit carries out the method until the gas pressure in the gas injector corresponds to the ambient pressure. As a result, the gas injector can be kept in a closed position without leakage when the internal combustion engine is stopped.
[0013] Furthermore, the invention relates to a computer program having a program code which executes the steps of the method according to the invention when the computer program is run on a computer or a corresponding processing unit, for example a control unit according to the invention.
[0014] Furthermore, a computer program product is proposed which comprises a computer program according to the invention, which is stored on a machine-readable data carrier or storage medium. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings:
[0016] Figure 1 A schematic diagram is shown which shows the voltage and current of the electromagnetic actuator according to the invention as a function of time, the force profile of the armature of the electromagnetic actuator as a function of time, and the travel during normal operation of the internal combustion engine,
[0017] Figure 2A schematic diagram is shown which shows the voltage and current of the electromagnetic actuator according to the invention over time, the force profile of the armature of the electromagnetic actuator over time, and the travel in the case of an exhaust function of an internal combustion engine, and
[0018] Figure 3 A longitudinal section through a gas injector which is provided for carrying out the method according to the invention is shown. DETAILED DESCRIPTION
[0019] Below, refer to Figures 1 to 3 A preferred embodiment of the present invention is described in detail.
[0020] Figure 3 A gas injector 1 with an electromagnetic actuator is shown by way of example. The electromagnetic actuator comprises an electromagnetic coil 3 for acting on an axially movable armature 2. The armature 2 can come into contact with a closing element 4, in particular a valve needle, in order to release the blowing cross section at a sealing seat 5. Reference numeral 8 denotes a reset element of the gas injector. The closing element 4 is held in place by means of a valve spring 7. Figure 3 in the closed position shown in .
[0021] If the electromagnetic coil 3 is energized, a magnetic field is generated, the magnetic force of which moves the armature 2 in the direction of the closing element 4 (arrow 11). Here, the armature pin 9 connected to the armature 2 abuts against the closing element 4, so that the closing element 4 opens at the sealing seat 5 against the spring force of the valve spring 7. Here, the armature 2 moves as far as the travel stop 6 for the armature, which represents the fully opened state of the gas injector.
[0022] To close the gas injector 1, the current supply to the electromagnetic coil 3 is terminated so that the reset element 8 resets the armature 2 to the position in which it is positioned. Figure 3 At the same time, the valve spring 7 also resets the closing element 4 to the initial position shown in FIG. Figure 1 in the closed position shown in .
[0023] The gas injector 1 is an injector which opens outwards.
[0024] It is preferable to use hydrogen, methane or the like as the gaseous fuel.
[0025] Figure 1 The graph in FIG. 1 shows the normal operation of a gas injector 1, which is used to inject gaseous fuel, especially hydrogen, directly into the combustion chamber of an internal combustion engine. Here, the gas injector and the electromagnetic actuator generally undergo four phases, namely, a lifting phase A, a pull-in phase B, a holding phase C, and a closing phase D.
[0026] exist Figure 1 and Figure 2In FIG. 1 , four curves are shown that vary with time t in four stages. Here, K1 shows the current variation of the electromagnetic actuator over time. K2 shows the average voltage of the electromagnetic actuator over time. K3 shows the force variation of the armature over time, and K4 shows the stroke of the armature over time t.
[0027] In addition, Figure 1 and Figure 2 Also shown in FIG. 5 is the closing force K5, which represents the difference between the system pressure in the gas injector and the spring force of the valve spring. Figure 1 In normal operation, the closing force is at F1, and at Figure 2 In the exhaust operation shown in FIG, the closing force is increased by F′ to F2 , since in the exhaust operation there is no auxiliary opening pressure provided by the pressure level of the gaseous fuel to be injected.
[0028] In addition, Figure 1 and Figure 2 Also plotted in FIG. 2 is the battery voltage K6 , which is constant both in normal operation and in exhaust operation.
[0029] like Figure 1 As shown, in normal operation of the internal combustion engine, the boost phase A ends after time t1, the pull-in phase B ends after time t2, the hold phase C ends after time t3, and the closing phase D ends after time t4.
[0030] In addition, Figure 1 In normal operation, the current curve K1 is such that the current level drops at the end of the pull-in phase and then remains at a constant level 11 during the pull-in phase. Figure 1 As further shown, the opening process begins during the transition between the lifting phase A and the closing phase B, ie the closing element begins to lift from the sealing seat. In the closing phase B, the maximum opening stroke is reached (stroke curve K4).
[0031] exist Figure 2 In the case of the exhaust function of the gas injector before the final shutdown of the internal combustion engine, as shown in FIG, the current curve K1 is such that in the boost phase A' the current increases continuously up to the point I1'. In the exhaust function, this current value I1' is maintained throughout the pull-in phase B'. Figure 1 and Figure 2 As shown in the comparison between the two, in the discharge function, the current level in the lifting phase A' or the pull-in phase B' is significantly higher than in normal operation. Figure 1 The current level during the pull-in phase A or the pull-in phase B.
[0032] In particular, in the exhaust function of the gas injector, the current level does not drop in the pull-in phase B'. At the end of the boost phase, the absolute value I1' is also greater than the value I1 in normal operation. This can be achieved by dimensioning the DC-DC converter and / or the boost capacitor. The DC-DC converter and the boost capacitor are dimensioned so that in normal operation ( Figure 1 ) can cope with all relevant operating points of the gas injector. In the case of a shutdown of the internal combustion engine and the subsequent necessary emission function (purge function), there are power reserves which are sufficient in the emission function for the few necessary injections, which are usually at lower speeds than in normal operation.
[0033] Therefore, energy reserves from the DC-DC converter and / or boost capacitors are used to Figure 2 The control for increasing the current level shown in Figure 2 Curve K1 in the pull-in phase B').
[0034] If Figure 1 and Figure 2 The comparison between the two further shows that the pull-in phase B'(t2'-t1') in the discharge operation is shorter than the pull-in phase B(t2-t1) in the normal operation. On the contrary, the boost phase A' in the discharge operation is longer than the boost phase in the normal operation due to the higher boost current level. Figure 2 This is shown by comparing the time t1 ′ with the time t1 in normal operation.
[0035] Due to the higher current level I1' in the exhaust operation, an increased opening force of the electromagnetic actuator is also provided, which can be achieved by Figure 1 and Figure 2 A comparison of the force profiles K3 between the two is shown. As a result, the missing force component of the gas pressure for opening the gas injector due to the drop in the gas pressure in the gas injector can be compensated. In the holding phases C, C' and the closing phases D, D' in the exhaust operation and the normal operation, all four curves K1, K2, K3 and K4 are again identical.
[0036] Therefore, a higher average voltage and thus also a higher pull-in current I1' can be achieved by regulating the pull-in current with an increased voltage in the pull-in phase B. Thus, a higher magnetic force can be generated by the electromagnetic actuator, which can compensate for the reduced opening pressure of the gaseous fuel to be injected.
[0037] In the described embodiment, an actuation variant with an increased boost current at the end of the boost phase A' is shown. However, other actuation variants are also conceivable in which the current profile in the boost phase A' in the discharge mode is the same as in the normal mode, and then compensation is only achieved by magnetic forces in the pull-in phase B' with the increased current.
Claims
1. A method for operating a gas injector of an internal combustion engine, the gas injector injecting gaseous fuel and having an electromagnetic actuator for actuating the gas injector, wherein: In an exhaust function, in which the gaseous fuel is discharged from the gas injector before the internal combustion engine is shut down so that the gaseous fuel is still combusted in the internal combustion engine before the internal combustion engine is finally shut down, the following steps are performed: The electromagnetic actuator is controlled in the lifting phase (A') so that the current (I) for the electromagnetic actuator is continuously increased until the lifting phase (A') ends, and In the pull-in phase (B') of the electromagnetic actuator, the current (I) is kept constant at a level corresponding to the maximum current intensity in the lifting phase (A') so that the reduced gas pressure in the gas injector during the discharge function of the gas injector is compensated by the increased actuator force of the electromagnetic actuator.
2. The method according to claim 1, wherein: The increased current requirement in the pull-in phase (B′) is provided by a boost capacitor and / or a DC-DC converter.
3. The method according to any one of the preceding claims, wherein: Compared to normal operation of the gas injector, the duration of the pull-in phase (B') is shortened.
4. The method according to any one of the preceding claims, wherein: The current level in the ramp-up phase (A') is increased compared to normal operation of the gas injector.
5. The method according to any one of claims 1 to 3, wherein: Compared to normal operation of the gas injector, the current level in the ramp-up phase (A') remains the same.
6. The method according to any one of the preceding claims, wherein: Compared to normal operation of the gas injector, the duration of the ramp-up phase (A') is prolonged.
7. The method according to any one of the preceding claims, wherein: Compared to normal operation of the gas injector, the holding phase (C') of the gas injector, during which the gas injector remains open, is prolonged.
8. A controller configured to carry out the steps of the method according to one of the preceding claims. 9 . A computer program having a program code which executes the steps of the method according to claim 1 , when the computer program is run on a computer or a corresponding computing unit, such as a control unit. 10 . A computer program product having a computer program according to claim 9 , which is stored on a machine-readable data carrier or storage medium.