Method for operating gas injector
By determining the start movement time point of the armature and the release time point of the brake current in the electromagnetic actuator of the gas injector, the problem of rebound during the gas injector is solved, achieving higher accuracy and lower noise.
Patent Information
- Application Number
- CN202380067807.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-21
- Filing Date
- 2023-06-28
- Publication Date
- 2025-04-29
AI Technical Summary
The gas injector is prone to rebound during shutdown, resulting in additional gas blowing, seal seat wear and increased noise.
By determining the time point in time for the armature of the electromagnetic actuator to start moving and the ideal release time point for the braking current, ensuring that the braking current of the armature during the closed movement can effectively reduce the impact speed and avoid rebound.
It effectively avoids the shutdown rebound of the gas injector, reduces the amount of errors in the gas to be blown, reduces noise, and improves the accuracy and robustness of the gas injector.
Smart Images
Figure CN119907883A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for operating a gas injector of an internal combustion engine in order to prevent a rebound of an armature of an electromagnetic actuator during the closing movement. Background Art
[0002] Gas injectors are known from the prior art in various configurations. Due to the gaseous media to be injected, such as hydrogen, methane or the like, it is necessary to improve the regulation of the opening and closing process of the gas injector in order to comply with the exact injection quantity. During the closing process, compared with injectors for liquid fuels, a so-called closing rebound can easily occur due to the lack of hydraulic damping. In the event of such a closing rebound, the gas injector opens again, thereby injecting an additional gas quantity, which significantly increases the defined injection quantity. This also leads to increased wear on the sealing seat and the generation of loud noises, especially in the event of multiple closing rebounds occurring in succession. Summary of the invention
[0003] The method according to the invention for operating a gas injector for an internal combustion engine to avoid a closing rebound of the armature of an electromagnetic actuator during the closing process, having the features of claim 1, has the following advantages: Closing rebound can be reliably avoided. As a result, the incorrect amount of gas to be injected is reduced and the noise behavior of the gas injector is also significantly improved. In this case, the method according to the invention is very robust and can be carried out repeatedly with high precision. According to the invention, this is achieved by:
[0004] The time of the start of movement of the armature of the electromagnetic actuator, at which the armature moves from the open fine adjustment in the direction of the closed position, can be determined in a simple manner. The time of the start of movement of the armature is determined solely on the basis of the voltage value of the electromagnetic actuator. Subsequently, the start of the braking current is also determined solely on the basis of the voltage profile of the electromagnetic actuator.
[0005] The ideal release time of the braking current of the electromagnetic actuator for braking the armature during the closing movement can thus be determined in a particularly simple but very precise manner. This can be ensured in particular under all possible operating conditions of the gas injector.
[0006] The braking current is a brief second activation of the gas injector during the closing movement of the armature in order to reduce the impact speed of the armature on the armature stop.
[0007] According to the present invention, the time point at which the armature starts to move from the open position in the direction of the closed position can be obtained only from the voltage variation curve of the electromagnetic actuator. During the closing process of the armature, due to the movement of the armature, an induced voltage is generated, which causes a slope change on the voltage signal. This is used to determine the time point at which the movement starts and to determine the start of the braking current of the armature.
[0008] The dependent claims reveal preferred developments of the invention.
[0009] Particularly preferably, the time of the start of the movement of the armature is determined on the basis of a local maximum of the voltage profile of the voltage after the current has been reduced to zero, for example by a control unit, to initiate a closing process of the gas injector.
[0010] Alternatively, the time of the start of the armature movement is determined using the difference between the detected voltage profile and a stored voltage profile of a basic profile, which is determined, for example, from tests during a closing process without armature movement.
[0011] For redundancy reasons, preferably both the difference curve and the local maximum of the voltage curve are detected and used for the release time of the braking current.
[0012] Particularly preferably, the start of the braking current is determined as a function of a local minimum of the voltage profile. Further preferably, the maximum movement speed of the armature during the closing process is set as a function of the local minimum.
[0013] Particularly preferably, the start of the braking current is determined from the time difference between a local maximum and a local minimum of the voltage profile. These two measured variables can be determined simply and quickly, wherein the time difference between a local maximum and a local minimum of the voltage profile can also be determined simply. This also allows the method according to the invention to be quickly adapted.
[0014] It is further preferred that the start of the braking current is determined from the difference and / or level difference of two measured variables, namely the local maximum of the voltage curve and the local minimum of the voltage curve. This determination of the start of the braking current can be performed separately or can also be used as a redundant determination of the start of the braking current.
[0015] In order to provide a particularly cost-effective solution, the start of the braking current is preferably determined by a characteristic map stored in a control unit of the gas injector on the basis of the time at which the armature begins to move determined from the voltage curve.
[0016] Preferably, the start of the braking current is adapted synchronously when the voltage profile is determined. Thus, if necessary, a correction (value) can be determined for each individual injection within the same cycle.
[0017] Alternatively, the start of the braking current is adapted as a sliding average of a predetermined number of detected voltage profiles. Thus, the start of the movement time and the start of the braking current can be determined from the preceding voltage profile.
[0018] The duration of the braking current is preferably determined by a characteristic map stored in the control unit as a function of the time at which the armature begins to move.
[0019] Particularly preferably, the method is carried out in such a way that the voltage profile of the electromagnetic actuator is determined only in the transition region between the non-ballistic region, in which the armature remains immobile in the open position, and the ballistic region, in which the armature moves. This further reduces the computational effort for the method according to the invention, since in particular it is not necessary to determine the entire voltage profile.
[0020] It is further preferred that the duration of the braking current of the electromagnetic actuator is changed according to the reset movement of the armature. Thus, the optimized damping of the reset movement of the armature can be achieved to reduce the reset speed of the armature, and thus closing rebound can be reliably avoided.
[0021] Furthermore, the invention relates to a control device which is configured to carry out the steps of the method according to the invention. Particularly preferably, the control device implements a control loop in order to improve the blowing accuracy of the gas injector by optimizing the closing process.
[0022] Furthermore, a computer program is proposed which has a program code and which executes the steps of the method according to the invention when it is run on a computer or a corresponding processing unit, for example a control unit according to the invention.
[0023] 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.
[0024] Furthermore, the invention relates to a gas injector for a gas internal combustion engine, which is configured to carry out the method according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings:
[0026] Figure 1 A schematic diagram is shown, which shows four graphs arranged one above the other to explain the method according to the invention according to a first embodiment of the invention,
[0027] Figure 2 The drawing shows a longitudinal section through a gas injector which is provided for carrying out the method according to the invention. DETAILED DESCRIPTION
[0028] Below, refer to Figure 1 and Figure 2 A first embodiment according to the present invention is described in detail.
[0029] Figure 2 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 2 in the closed position shown in .
[0030] When 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 until the travel stop 6 for the armature, which represents the fully opened state of the gas injector.
[0031] In order 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 again. Figure 1 At the same time, the valve spring 7 also resets the closing element 4 to the initial position shown in FIG. Figure 2 in the closed position shown in .
[0032] Figure 1 The method according to one embodiment of the present invention is schematically shown. In order to explain the present invention more clearly, four graphs arranged one above the other are shown to improve the process of the present invention and the understanding of the present invention.
[0033] Figure 1 The upper graph in FIG. 1 shows the current I supplied to the electromagnetic actuator as curve A over time t. Starting from the zero point representing the closed state of the gas injector without power (I=0), the current rises rapidly after receiving the opening command for the electromagnetic actuator. Subsequently, the current I is kept constant for the time t until the injection is to be ended (point E), and the current for the electromagnetic actuator drops to zero again very quickly. This time point is Figure 1In the upper graph of , t0 is indicated. After a predetermined time period between time t0 and time t1 has elapsed, a braking current B is activated in order to reduce the movement speed of the armature before the armature strikes the armature stop. Figure 1 In the upper graph, the braking current is maintained until time point t2.
[0034] exist Figure 1 In the figure, the second graph from the top shows the voltage variation curve of voltage U over time t. As can be seen from curve C, when the gas injector starts to open, the voltage rises rapidly, and then the voltage is maintained in a narrow range to achieve the opening. At the end of the control, the voltage variation curve C becomes negative (U<<0V) (time point t0).
[0035] The third graph from the top shows the travel H of the gas injector over time t, starting from the open state at a time t of approximately 3 milliseconds.
[0036] Figure 1 The bottom graph shows the line pressure P as a function of time t. Figure 1 It can be seen that after the gas injector is fully opened, the line pressure P drops relatively strongly and only rises again after the gas injector is fully closed.
[0037] In the transition region between the non-ballistic region of the armature, in which the armature does not move (open state of the armature), and the ballistic region of the armature, in which the armature moves from the open state into the closed state, three alternative curves are plotted in the three graphs above for current I, voltage U and stroke H of the gas injector.
[0038] As can be seen from the second curve diagram of voltage U changing with time t from the top, the time point L of the armature's start of movement in the closing direction can be determined only based on the voltage change curve C of the electromagnetic actuator. After the time point t0 (at which the command for closing the gas injector is issued due to the opening pulse of the controller), the voltage U remains at the arc extinguishing voltage level (U<<0V) for a short time and then slowly rises to the zero level. This maximum value determines the time point L of the armature's start of movement for the closing movement.
[0039] In the voltage curve, a basic curve G is plotted as a dotted line, which shows the voltage curve when there is no armature movement. The basic curve G can be obtained, for example, by laboratory tests or the like.
[0040] As per Figure 1It can be seen from the voltage curve C in that at the start of the movement time L, the voltage U changes and decreases due to the movement of the armature. Here, in the subsequent time curve, a minimum value M in the voltage curve can be seen, in which the armature has its highest speed during the closing movement. Figure 1 Three curves are schematically shown in FIG. 1 , wherein arrow R represents the slower valve closing of three different voltage curves. Figure 1 In the third curve diagram of FIG. 1 , the valve stroke moves backward in time, so that the closing time point of the gas injector moves further backward in time ( Figure 1 , as shown in the figure.
[0041] like Figure 1 It can be further seen that the braking current starts at time t1, at which time the voltage curve C reaches a local minimum M at the beginning of the closing, at which the armature speed is also the highest. It should be noted that after the braking current is turned on, the voltage curve C suddenly rises (U>0V). For simplicity, this fact is Figure 1 Not shown.
[0042] It should be noted that the maximum armature speed can also be determined via a difference curve between the base curve G and the detected voltage profile C.
[0043] Thus, the closing speed of the gas injector can be determined by means of this second measured variable of the local minimum M of the voltage curve C. Here, the voltage drops faster as the closing speed increases. The turning point of the local minimum M is thus reached earlier. The valve speed can be determined either by measuring the measured variable Δt in time or by measuring the measured variable ΔU of the voltage at two points in time in time. Here, the two measured variables Δt and ΔU can be compared with setpoint values stored, for example, in a controller, and in the case of deviations, correction values can be determined according to the correction characteristic curve diagram stored in the controller. Here, the correction of the start of the braking current can either be carried out in the same cycle, i.e., a so-called synchronous correction (in which a new correction value is determined for each individual injection), or can be carried out slowly as a sliding average value determined from a plurality of measurement cycles.
[0044] The present invention therefore makes it possible to detect relatively accurately with relatively little effort, in particular in the transition region around the time of the start of the movement of the magnet armature.
[0045] It should be noted that the method is also feasible, for example, when the voltage profile C is determined only in a region around the start of the movement time L. In this way, in particular the calculation time and the costs can be reduced due to the reduced effort.
Claims
1. A method for operating a gas injector, the method for determining the start of a braking current to reduce the closing rebound of an armature of an electromagnetic actuator, the method comprising the following steps: Determining a voltage variation curve C of the electromagnetic actuator over time t; determining a time point L at which the armature starts to move from an open position of the gas injector toward a closed position based only on the voltage variation curve C of the electromagnetic actuator; and The start of the braking current is determined solely on the basis of the voltage profile C of the electromagnetic actuator.
2. The method according to claim 1, wherein: The armature movement start time L is determined based on the local maximum of the voltage variation curve C of the electromagnetic actuator.
3. The method according to any one of the preceding claims, wherein: The start of the braking current B is determined as a function of a local minimum M of the voltage profile C of the electromagnetic actuator.
4. The method according to claim 1, wherein: The movement start time L is determined by the difference between the detected voltage profile and the voltage profile of the stored basic profile.
5. The method according to any one of the preceding claims, wherein: The start of braking current B is determined by the time difference between two measured variables, namely the time difference between a local maximum of voltage profile C and a local minimum M of voltage profile C.
6. The method according to any one of the preceding claims, wherein: The start of braking current B is determined by the difference and / or level difference of two measured variables, namely the difference and / or level difference of a local maximum of voltage curve C and a local minimum M of voltage curve C.
7. The method according to any one of the preceding claims, wherein: When determining the voltage profile C, the start of the braking current B is adapted synchronously.
8. The method according to any one of claims 1 to 6, wherein: The start of braking current B is adapted as a sliding average value of a predetermined number of determined voltage profiles.
9. The method according to claim 8, wherein: A target time period is determined by a controller of the internal combustion engine.
10. A controller configured to perform the steps of the method according to one of the preceding claims. 11 . 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. 12 . A computer program product having a computer program according to claim 11 , which is stored on a machine-readable data carrier or storage medium.