Electromagnetically actuatable fuel valve and method for operating the electromagnetically actuatable fuel valve
Patent Information
- Application Number
- EP2023762399
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-01
- Filing Date
- 2023-08-28
- Publication Date
- 2025-07-09
AI Technical Summary
Existing electromagnetically controllable fuel valves lack precision in measuring the stroke of the magnet armature, which is essential for calculating individual control times and accurate injection quantities, typically requiring a separate position measuring sensor.
The fuel valve features a magnetic circuit with a profiled outer contour of the magnet armature and inner contour of the pole body, allowing the evaluation of current or voltage profiles to derive direct information about the path traveled by the magnet armature, enabling precise stroke determination without a position sensor.
This geometric design of the magnetic circuit provides precise determination of the magnet armature's stroke and speed, enhancing the metering accuracy and enabling precise injection quantities by extrapolating from multiple known positions, thus improving the control times and overall metering accuracy.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Title:
[0003] Electromagnetically controlled fuel valve, method for operating the electromagnetically controlled fuel valve
[0004] The present invention relates to an electromagnetically controllable fuel valve for metering a fuel according to the preamble of claim 1. Such a fuel valve is also called a metering or injection valve. The fuel can be, in particular, a gaseous fuel, for example, hydrogen or natural gas, which is required to operate an internal combustion engine or a fuel cell system.
[0005] Furthermore, the invention relates to a method for operating the electromagnetically controllable fuel valve.
[0006] State of the art
[0007] A variety of metering or injection valves are known from the prior art. These are electromagnetically controlled and have a solenoid coil for acting on a movable solenoid armature, which can be coupled to a valve element or forms the valve element itself. The valves are generally designed as normally closed valves, so that the solenoid coil must be energized to open. When the solenoid coil is energized, a magnetic field is created, the magnetic force of which acts on the solenoid armature, causing it to perform a lifting movement. The lifting movement of the solenoid armature opens the fuel valve.
[0008] To monitor the functionality and thus the metering accuracy of a fuel valve, the times of start-up and stop of the solenoid armature can be determined. Various methods are known from the state of the art. These methods generally have in common that the current flowing through the solenoid coil during opening is recorded and evaluated. For example, an inductance curve can be calculated from the current curve, and by evaluating a change in inductance, the start-up time of the solenoid armature can be determined. Reaching a predetermined inductance threshold indicates the stop time.
[0009] State-of-the-art methods enable the temporal detection of the beginning and end of a solenoid armature's stroke movement from the current or voltage profile of the solenoid coil. However, it would be advantageous to know the actual stroke or the distance traveled by the solenoid armature, which would allow for the calculation of individual actuation times based on this information, which in turn would enable very precise injection quantities. However, detecting the stroke or distance requires a separate measurement using a distance sensor.
[0010] The invention is concerned with the task of detecting the stroke of the magnet armature without using a position measuring sensor in order to increase the dosing accuracy of an electromagnetically controlled fuel valve.
[0011] To achieve this object, the electromagnetically controllable fuel valve having the features of claim 1 and the method having the features of claim 5 are proposed. Advantageous further developments of the invention can be found in the respective subclaims.
[0012] Disclosure of the invention
[0013] The electromagnetically controllable fuel valve proposed for metering a preferably gaseous fuel comprises a magnetic coil for acting on a reciprocating magnet armature, which is designed as a plunger armature and is surrounded at least in sections by a pole body, so that the magnet armature and the pole body together define a radial air gap. According to the invention, in the region of the radial air gap, the magnet armature has an outer contour profiled in the direction of movement, and the pole body has an inner contour profiled in the direction of movement of the magnet armature, so that the radial air gap changes with the reciprocating movement of the magnet armature.
[0014] The geometric design of the magnetic circuit of the proposed fuel valve enables an evaluation of the current or voltage profile, revealing at least two positions in the stroke of the armature. In this way, in addition to temporal information, direct information about the distance traveled by the armature can be derived from the current or voltage signal. Using models, the speed and total stroke of the armature can then be determined. This information can then be used to calculate individual actuation times and thus very precise injection quantities.
[0015] Typically, the radial air gap between a solenoid armature and a pole body is defined by straight, cylindrical surfaces, resulting in a simple annular gap. The radial air gap is also usually chosen to be as small as possible to keep magnetic losses to a minimum.
[0016] In the proposed fuel valve, the outer contour of the magnet armature and the inner contour of the pole body deviate from a pure cylindrical shape, creating a radial air gap that—depending on the axial position of the magnet armature—leads to a change in the magnetic flux in the radial air gap. This change is reflected in the induced voltage and inductance curves, so that the curves can be used to determine the displacement position of the magnet armature. The more displacement positions are known over the entire stroke, the more accurately the total displacement of the magnet armature can be determined by extrapolation.
[0017] Preferably, the outer contour of the magnet armature and the inner contour of the pole body are designed to be diametrically opposed. This allows for discontinuous or cyclical changes in the magnetic flux in the radial air gap, which allow for particularly clear detection of different armature travel positions.
[0018] According to a preferred embodiment of the invention, the outer contour of the magnet armature and the inner contour of the pole body are designed with multiple steps in the direction of movement of the magnet armature. This multiple stepping results in the formation of at least one axial air gap in the area of the radial air gap, which changes depending on the axial position of the magnet armature relative to the pole body.
[0019] According to a further preferred embodiment of the invention, the outer contour of the magnet armature and the inner contour of the pole body are profiled in a sawtooth-like manner in the direction of movement of the magnet armature. To avoid blocking the reciprocating movement of the magnet armature, the sawtooth-like profiles do not mesh with each other, but rather maintain a radial distance. However, the reciprocating movement of the magnet armature relative to the pole body changes the distances between the surfaces opposite each other at the radial air gap, so that the magnetic flux in the radial air gap changes cyclically along the reciprocating movement of the magnet armature.
[0020] Furthermore, a method for controlling an electromagnetically controllable fuel valve according to the invention for metering a preferably gaseous fuel is proposed. In the method, a magnetic coil acting on a movable magnet armature is energized to open the fuel valve. The method also evaluates the current and / or voltage curves. According to the invention, at least two axial positions in the stroke of the magnet armature are determined based on the current and / or voltage curves and used to calculate the distance traveled by the magnet armature.
[0021] The method is based on the realization that, with an appropriate geometric design of the magnetic circuit, the evaluation of the current and / or voltage curve not only provides temporal information about the stroke curve of the armature, but also information about the actual distance traveled. With an appropriate geometric design of the magnetic circuit, the magnetic flux in the radial air gap between the armature and the pole body changes depending on the axial position of the armature in relation to the pole body. This change is reflected in the curves of the induced voltage and the inductance, so that the curves can be used to determine the travel position of the armature. The more travel positions are known over the entire stroke curve, the more accurately the total stroke of the armature can be determined, for example by extrapolation.
[0022] The outer contour of the magnet armature and the inner contour of the pole body are each profiled in the direction of movement of the magnet armature, so that both the magnet armature and the pole body have diametrically opposed sections. For example, the magnet armature and the pole body can be designed with multiple steps or a sawtooth profile. Depending on the axial position of the magnet armature relative to the pole body, the magnetic flux in the radial air gap between the magnet armature and the pole body changes.
[0023] Depending on the specific geometric design of the magnetic circuit, the magnetic flux in the radial air gap changes discontinuously or cyclically. The latter is the case, for example, with a sawtooth profile. The discontinuous or cyclical change can be read from the induced voltage and inductance curves and thus used to determine the axial position of the magnet armature at the respective times. If at least two axial positions of the magnet armature are known over the stroke curve, the total stroke can be calculated from this, for example by extrapolation.
[0024] Furthermore, it is proposed that the speed of the magnet tanker and / or the total stroke of the magnet armature be determined by extrapolation with the aid of at least one model. This information can then be used to calculate individual control times, thus increasing the accuracy of the injection quantities or the metering accuracy of the fuel valve. The proposed method is used to determine at least two axial positions of the magnet armature during its stroke movement, i.e., during the stroke course. An axial position can also be an end position of the magnet armature. The total stroke of the magnet armature can then be determined from the at least two known axial positions.
[0025] To determine the end position of the magnet armature, the time of the beginning and / or the time of the end of the magnet armature's stroke movement can be determined by evaluating the inductance curve, for example, according to the state of the art mentioned above. The proposed method can therefore be combined with previously known methods for determining temporal information about the magnet armature's stroke curve.
[0026] Furthermore, it is preferred that a model be used to extrapolate the times of the beginning and end of the stroke movement of the magnet armature to determine the axial position of the magnet armature at the respective time.
[0027] The invention and its advantages are described in more detail below with reference to the accompanying figures. These show:
[0028] Fig. 1 is a schematic longitudinal section through a first fuel valve according to the invention in the region of a magnetic circuit, comprising a magnetic coil, a pole body and a magnet armature,
[0029] Fig. 2 is a schematic longitudinal section through a second fuel valve according to the invention in the region of a magnetic circuit, comprising a magnetic coil, a pole body and a magnet armature,
[0030] Fig. 3 diagrams showing the time course of a) the voltage U and b) the inductance L when the magnetic coil of the magnetic circuit shown in Figure 1 is energised, Fig. 4 diagrams showing the time course of a) the voltage U and b) the inductance L when the magnetic coil of the magnetic circuit shown in Figure 2 is energised and
[0031] Fig. 5 is a path-time diagram illustrating the stroke profile of a magnet armature of a fuel valve according to the invention.
[0032] Detailed description of the characters
[0033] Figures 1 and 2 each show a preferred embodiment of a fuel valve 1 according to the invention, wherein the fuel valve 1 is designed as an electromagnetically controllable and normally closed valve. Figures 1 and 2 are limited to the representation of the magnetic circuit 10 of the respective fuel valve 1, wherein the magnetic circuit 10 each comprises a magnetic coil 2 for acting on a movable magnet armature 3 and a pole body 4 accommodating the magnet coil 2. The magnet armature 3 is designed as a plunger armature and, together with the pole body 4, defines an axial air gap 9 and a radial air gap 5.
[0034] In the embodiment according to Figure 1, the magnet armature 3 has an outer contour 7 in the region of the radial air gap 5, which is profiled in the direction of movement 6 of the magnet armature 3. The pole body 4 has an inner contour 8 in the region of the radial air gap 5, which is also profiled in the direction of movement 6 of the magnet armature 3. The contours each have a sawtooth profile, but they do not mesh with each other, so that the stroke of the magnet armature 3 is not restricted.
[0035] Due to the geometric design of the magnetic circuit 10 shown in Figure 1, at least two axial positions in the stroke of the armature 3 can be determined by evaluating the current or voltage curve. In addition to the temporal information, information about the distance traveled by the armature 3 can thus be obtained. This is because the geometric design of the magnetic circuit 10 shown causes the radial air gap 5 to change depending on the axial position of the armature 3. This simultaneously changes the magnetic flux in the radial air gap 5, with the change being cyclical. The change can be read off - as shown by way of example in the diagrams in Figure 3 - in the curves of the induced voltage U (diagram a)) and the inductance L (diagram b)). By evaluating the curves, the axial position of the armature 3 can be determined via the stroke curve, because the following applies:
[0036] At — f(x,y,v)
[0037] If at least two axial positions of the magnet armature 3 are known over the stroke course, the speed v and / or the total stroke of the magnet armature 3 can be determined by extrapolation.
[0038] Figure 2 shows another fuel valve 1 according to the invention and its magnetic circuit 10. In this exemplary embodiment, the outer contour 7 of the magnet armature 3 is designed with multiple steps in the direction of movement 6 of the magnet armature 3. The same applies to the inner contour 8 of the pole body 4. The steps of the outer contour 7 have different distances Xi and X2 from the steps of the pole body 4, where X2>Xi in this case. If the magnet armature 3 performs a stroke movement, the distances Xi and X2 change. These changes can be read off in the curves of the induced voltage U (diagram a)) and the inductance L (diagram b)) - as shown by way of example in the diagrams in Figure 4. By evaluating the curves, the axial position of the magnet armature 3 can be determined via the stroke curve, because the following applies:
[0039] At — / '(x1,x2, v)
[0040] If at least two axial positions of the magnet armature 3 are known over the stroke course, the speed v and / or the total stroke of the magnet armature 3 can be determined by extrapolation.
[0041] The path-time diagram shown in Figure 5 shows a typical stroke profile of a magnet armature 3 of a fuel valve 1 according to the invention. With the aid of the method according to the invention, points B and C can be determined directly from the current and / or voltage curve both in relation to time t and in relation to path x. Points A and D, which define the start and end of the stroke movement of the magnet armature 3, can be determined, for example, using a method known from the prior art in relation to time t. By extrapolation, the respective path x at points A and D can then be deduced, so that the entire stroke and its profile can be determined from this.
[0042] The more points are known about the stroke curve in relation to time t and distance x, the more accurately the extrapolation can be carried out.
Claims
Claims 1. Electromagnetically controllable fuel valve (1) for metering in a preferably gaseous fuel, comprising a magnetic coil (2) for acting on a reciprocating magnet armature (3), which is designed as a plunger armature and is surrounded at least in sections by a pole body (4), so that the magnet armature (3) and the pole body (4) together delimit a radial air gap (5), characterized in that in the region of the radial air gap (5) the magnet armature (3) has an outer contour (7) profiled in the direction of movement (6) and the pole body (4) has an inner contour (8) profiled in the direction of movement (6) of the magnet armature (3), so that the radial air gap (5) changes with the reciprocating movement of the magnet armature (3).
2. Fuel valve (1) according to claim 1, characterized in that the outer contour (7) of the magnet armature (3) and the inner contour (8) of the pole body (4) are designed to be diametrically opposed.
3. Fuel valve (1) according to claim 1 or 2, characterized in that the outer contour (7) of the magnet armature (3) and the inner contour (8) of the pole body (4) are designed with multiple steps in the direction of movement (6) of the magnet armature (3).
4. Fuel valve (1) according to one of the preceding claims, characterized in that the outer contour (7) of the magnet armature (3) and the inner contour (8) of the pole body (4) are profiled in a sawtooth manner in the direction of movement (6) of the magnet armature (3).
5. Method for controlling an electromagnetically controllable fuel valve (1) for metering in a preferably gaseous fuel according to one of the preceding claims, in which, in order to open the fuel valve (1), a magnetic coil (2) acting on a stroke-movable magnet armature (3) is energized and the current and / or voltage curve is or are evaluated, characterized in that at least two axial positions in the stroke curve of the magnet armature (3) are determined on the basis of the current and / or voltage curve and used to calculate the distance traveled by the magnet armature.
6. Method according to claim 5, characterized in that the speed (v) of the magnet tanker (3) and / or the total stroke of the magnet armature (3) is / are determined with the aid of at least one model by extrapolation.
7. Method according to claim 6, characterized in that the speed (v) and / or the total stroke of the magnet armature (3) are used to calculate individual control times.
8. Method according to one of claims 5 to 7, characterized in that the time of the beginning and / or the time of the end of the stroke movement of the magnet armature (3) is or are determined by evaluating the inductance curve.
9. Method according to claim 8, characterized in that the axial position of the magnet armature (3) at the respective time is determined with the aid of a model by extrapolating the times of the beginning and the end of the stroke movement of the magnet armature (3).