Method of determining armature position of an electromagnet and fluid system

Abstract

The invention relates to a method for determining a position of an armature of an electromagnet, a method for determining a position of a valve element of an electromagnetically driven fluid valve, and a fluid system comprising an electromagnetically driven fluid valve and an electronic control unit for performing the method for determining the position of the valve element. The electronic control unit applies a current profile in the coil of the electromagnet which is not driven, wherein the current profile is substantially below a minimum drive current of the electromagnet. By applying the current profile, the electronic control unit determines a characteristic curve of the electromagnet. Thus, the electronic control unit can switch off the current in the coil of the electromagnet during a third time interval t3-t4 and t3-t4' and determine a position characteristic of the electromagnet depending on a first time T1, T1' and a second time T2, T2'. Subsequently, the electronic control unit can calculate the position of the armature of the electromagnet which is not driven based on the compensation characteristic and the position characteristic.

Description

Technical Field

[0001] The present invention relates to a method for determining the position of the armature of an electromagnet, a method for determining the position of a valve component in an electromagnetically driven fluid valve, and a fluid system including an electromagnetically driven fluid valve and an electronic control unit. Background Technology

[0002] To achieve the objectives of this invention, the fluid system refers to a hydraulic system or a pneumatic system. Therefore, the fluid valve can be a hydraulic valve or a pneumatic valve.

[0003] Fluid systems comprising electromagnetically driven fluid valves and electronic control units can provide users with a variety of functions. For example, such fluid systems may include direct-controlled electromagnetically driven fluid valves having a first electromagnet and a second electromagnet operating complementaryly to the first electromagnet, wherein both the first and second electromagnets are controlled by an electronic control unit. Such fluid valves can, for example, provide a volumetric flow rate to the user based on the variable opening cross-section of the fluid valve. In this case, the first and second electromagnets can be controlled by the electronic control unit to move the valve element of the fluid valve. This valve element can be, for example, a spool valve piston or a valve cone of a seat valve. For this purpose, an actuating element can be connected to the armature of each electromagnet, such that an actuating element such as an actuating rod directly transmits the movement of the armature of each electromagnet to the valve element. By moving the valve element, the opening cross-section of the fluid valve can be changed, thereby enabling the fluid valve to provide a volumetric flow rate dependent on the opening cross-section.

[0004] The opening cross-section of this type of fluid valve primarily depends on the mutual energization of two electromagnets. Therefore, the electronic control unit can essentially control the volumetric flow rate through the fluid valve by controlling the energization of the two electromagnets. However, the actual opening cross-section of the fluid valve also depends on other parameters, such as hysteresis, friction, system pressure, or temperature parameters such as ambient and system temperatures. These disturbance variables can cause generally undesirable control errors, which need to be compensated for. For this reason, existing technologies often use independent position sensors to monitor the position of the valve and downstream control loops. Depending on the measurement mode, newer position sensors have two to three coils for detecting the position of the armature within the coils. This allows the measurement mode to be unaffected by temperature, thus ensuring high spatiotemporal resolution of the position measurement. However, such position sensors are expensive and require additional installation space. Furthermore, each additional component added to the system naturally means an additional potential source of error. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide a possibility for monitoring the valve position of a direct-controlled electromagnetically driven fluid valve, which is cheaper, requires less installation space, and reduces the risk of component failure compared to existing solutions.

[0006] First, the above problem can be solved by the method for determining the position of the armature in an electromagnet according to claim 1.

[0007] According to the present invention, a method for determining the position of the armature of an electromagnet is provided, particularly a method for determining the position of the armature of an electromagnet in an electromagnetically driven fluid valve, the electromagnet comprising a coil and an armature, and the method being executed by an electronic control unit. The method includes the following steps:

[0008] A current profile is applied to the coil of the electromagnet, wherein the current profile is approximately lower than the minimum drive current of the electromagnet.

[0009] Determine the characteristic curve of the electromagnet; and

[0010] The position of the armature of the electromagnet is calculated based on the characteristic curve.

[0011] Specifically, the electromagnet is an electromagnet for a direct-controlled electromagnetically driven fluid valve. Specifically, the direct-controlled electromagnetically driven fluid valve is a direct-controlled electromagnetically driven hydraulic valve.

[0012] The minimum driving current of the electromagnet should be understood as the current that must be sufficient to flow in the coil of the electromagnet to move the armature of the electromagnet and thus switch the fluid valve. The fact that the current curve is generally lower than the minimum driving current means that the maximum current value of the current curve can also be temporarily higher than the minimum driving current, but the current curve will not cause the entire armature of the electromagnet to move. Due to the inertia of the fluid valve, even if the current peak is higher than the minimum driving current, it will not cause the armature of the electromagnet to move as long as the time is short enough. Therefore, the current curve is such that when the current in the electromagnet coil follows the current curve, the current in the electromagnet coil will not cause the armature of the electromagnet to move. In other words, when the current in the electromagnet coil is generally lower than the minimum driving current, the electromagnet will not be driven. Therefore, for the purposes of this invention, the fact that the electromagnet is not driven means that the electromagnet will not be used to switch the fluid valve. Of course, the armature of the undriven electromagnet can be indirectly moved, for example, by driving the fluid valve with another electromagnet.

[0013] In this invention, a characteristic curve is understood to be one or more characteristic values ​​or measurements that can be calculated from each other, for example. The characteristic curve includes values ​​determined by the method according to the invention, but may also include system-specified values, such as temperature coefficients or other unique coefficients of each electromagnet.

[0014] As used herein, the term "determine" includes one or more process steps, such as control, regulation, measurement, and / or calculation, to determine a corresponding value. Values ​​specified by the system may also be used to perform the determination.

[0015] Specifically, the electronic control unit includes a current sensor and an electromagnet control unit, wherein the current sensor is used to measure the current in the coil of the electromagnet, and the electromagnet control unit is used to control the drive of the electromagnet by means of a power supply voltage in a generally known manner.

[0016] According to the method of the present invention, if the electromagnet is not driven, that is, if the electromagnet is not used to switch the fluid valve at the moment the position is determined according to the present invention, then the position of the armature of the electromagnet can be determined by means of the characteristic curve without the need for a separate position sensor. Therefore, an undriven electromagnet can be used to perform the function of a position sensor. This not only saves manufacturing costs and reduces the required installation space, but also reduces the overall number of system components required due to the omission of the position sensor, thereby improving the reliability of the entire system equipped with the electromagnet.

[0017] Preferably, the method according to the present invention is configured such that applying the current curve includes the following steps:

[0018] Within the first time interval, the current in the coil of the electromagnet is set to a first limited current value;

[0019] During the second time interval, the current in the coil of the electromagnet is adjusted to the first predetermined current value; and

[0020] During the third time interval, the current in the coil of the electromagnet is cut off;

[0021] Furthermore, determining the characteristic curve includes the following steps:

[0022] Determine the compensation characteristics of the electromagnet in the second time interval; and

[0023] Determine the positional characteristics of the electromagnet during the third time interval.

[0024] Specifically, setting the current in the electromagnet's coil to a first predetermined current value includes rapidly controlling the current in the electromagnet's coil. The sole purpose of this rapid control is to set the current to the first predetermined current value as quickly as possible. Specifically, during this rapid control, the electromagnet control unit can switch the power supply voltage non-clockwise until the current in the electromagnet's coil, as measured by the current sensor, matches the first predetermined current value. Rapidly controlling the current in the electromagnet's coil can also be referred to as rapidly energizing the electromagnet.

[0025] Specifically, cutting off the current in the electromagnet's coil means not applying an external voltage to the electromagnet; therefore, the energy stored in the electromagnet during the second time interval will dissipate during the third time interval. The state during the third time interval is also referred to as active free operation.

[0026] According to the method of the present invention, when the electromagnet is not driven, the position of the armature in the electromagnet can be determined by compensation characteristics and position characteristics without the need for a separate position sensor. Therefore, an undriven electromagnet can be used to perform the function of a position sensor. This not only saves manufacturing costs and reduces the required installation space, but also, by omitting the position sensor, reduces the overall number of system components required, thereby improving the reliability of the entire system equipped with the electromagnet.

[0027] Preferably, the compensation characteristic of the electromagnet is a temperature-dependent compensation characteristic. This allows the temperature dependence to be taken into account and compensated for when determining the position of the armature of the electromagnet.

[0028] Preferably, the temperature-dependent compensation characteristic of the electromagnet is the resistance of the electromagnet's coil, particularly the copper resistance. Determining the copper resistance of the electromagnet's coil within the second time interval is relatively easy.

[0029] Preferably, the positional characteristics of the electromagnet are those that vary with temperature and inductance. Temperature dependence can be compensated for by assigning compensation characteristics. Specifically, the inductance of the electromagnet depends on the position of the armature in the coil; therefore, the position of the armature in the coil can be calculated using inductance dependence.

[0030] Furthermore, preferably, the positional characteristic of the electromagnet, which varies with temperature and inductance, is the rate of current decrease in the coil of the electromagnet. The rate of current decrease in the coil of the electromagnet depends on the inductance of the electromagnet, and therefore also on the position of the armature in the coil. It is well known that the armature is specifically made of ferromagnetic material. Therefore, the inductance of the electromagnet reaches its maximum when the armature is fully located in the coil. If the armature is only partially located in the coil, the inductance of the electromagnet decreases accordingly. In the third time interval, the energy stored in the electromagnet in the second time interval is dissipated essentially as a current passing through the copper resistance of the coil. The stored energy depends on the inductance of the electromagnet, and therefore also on the position of the armature in the coil. Furthermore, the rate of current decrease also depends on temperature. This temperature dependence can be compensated for by a distribution compensation characteristic. Therefore, the position of the armature in the coil can be calculated from the rate of current decrease of the electromagnet. The higher the rate of current decrease, the smaller the inductance of the electromagnet, and the more off-center the armature is in the coil, and vice versa.

[0031] Preferably, adjusting the current in the electromagnet's coil to a first predetermined current value within the second time interval is achieved through pulse width modulation. This allows for precise control of the current in the electromagnet's coil and reduces its losses.

[0032] Advantageously, determining the compensation characteristics of the electromagnet includes: determining the average voltage passing through the electromagnet, determining the average current in the coil of the electromagnet, and calculating the compensation characteristics based on the average voltage and average current. The average voltage passing through the electromagnet is the voltage required to regulate the current in the coil of the electromagnet to a first predetermined current value. Specifically, the first predetermined current value is set as the average current in the coil of the electromagnet. Alternatively, determining the average current in the coil of the electromagnet includes measuring the average current in the coil of the electromagnet. Depending on how the current in the coil of the electromagnet is regulated to the first predetermined current value, the average current in the coil of the electromagnet may differ slightly from the first predetermined current value. Therefore, it is advantageous to measure the average current to make the results obtained when determining the compensation characteristics more accurate. In view of this, the compensation characteristics can be determined based on readily available values.

[0033] Preferably, determining the average voltage across the electromagnet involves measuring the power supply voltage during the second time interval and multiplying the measured power supply voltage by the duty cycle of the pulse width modulation. This allows for efficient and accurate determination of the average voltage across the electromagnet.

[0034] Alternatively, determining the average voltage across the electromagnet involves measuring the voltage across the electromagnet during a second time interval and averaging the measured voltages across the electromagnet. Thus, another method for determining the average voltage across the electromagnet is shown.

[0035] Alternatively, applying the current profile includes the following steps:

[0036] During the first time interval, an adjusting voltage is applied to the coil of the electromagnet until a first predetermined current value is reached; and

[0037] During the third time interval, the current in the coil of the electromagnet is cut off;

[0038] Furthermore, determining the characteristic curve includes the following steps:

[0039] Determine the compensation characteristics of the electromagnet in the first time interval; and

[0040] Determine the positional characteristics of the electromagnet during the third time interval.

[0041] According to this alternative method, the first time interval and the second time interval can be combined to form a new first time interval. Within this first time interval, a defined regulating voltage is applied to the coil of the electromagnet to maintain the same general conditions throughout the first time interval.

[0042] When the coil of the electromagnet reaches the first limited current value, the current in the coil of the electromagnet is cut off, and as described above, the third time interval is directly activated. Therefore, the only difference between this alternative method and the method described above is the configuration of the first time interval when determining the compensation characteristics.

[0043] Furthermore, according to the alternative method of the present invention, when the electromagnet is not driven, the position of the armature of the electromagnet can be determined by compensation characteristics and position characteristics without the need for a separate position sensor. Therefore, the aforementioned further advantages regarding the omission of a position sensor naturally also apply to this alternative method.

[0044] Preferably, in an alternative method according to the invention, the compensation characteristic is the rate of current increase in the coil of the electromagnet. The rate of current increase in the coil of the electromagnet depends on the temperature and the inductance of the electromagnet. The temperature dependence of the rate of current increase in the coil is inversely related to the temperature dependence of the rate of current decrease in the coil. This means that the rate of current increase can also be used as a compensation characteristic for temperature compensation.

[0045] Preferably, determining the position characteristic includes: detecting a first moment when the current in the coil of the electromagnet reaches a second predetermined current value; detecting a second moment when the current in the coil of the electromagnet reaches a third predetermined current value lower than the second predetermined current value; and calculating the position characteristic based on the time difference between the second moment and the first moment, and the current difference between the second predetermined current value and the third predetermined current value. Specifically, the second predetermined current value is lower than the first predetermined current value. This avoids uncertainties or ambiguities in the measurement when detecting the first moment. Therefore, the second predetermined current value and the third predetermined current value are fixed thresholds for the current in the coil of the electromagnet, and when they are reached, the first moment and the second moment can be detected respectively. Accordingly, the current difference can be predetermined as a constant, while the time difference varies according to the position of the armature in the coil. This ensures the comparability of the position characteristic results, thus enabling determination in a simple manner.

[0046] Preferably, the above process steps are repeated. By repeating the above process steps, the position of the armature of the electromagnet can be continuously determined even when the electromagnet is not driven.

[0047] In addition, a method for determining the valve position of an electromagnetically driven fluid valve is provided to solve the above-mentioned problem, wherein the electromagnetically driven fluid valve includes a valve element and an electromagnet for driving the valve element, the electromagnet including a coil and an armature, and the method includes the following steps:

[0048] The position of the armature of the electromagnet (23) is determined by the method according to the present invention; and

[0049] The position of the valve is calculated based on the position of the armature of the electromagnet.

[0050] Specifically, this electromagnetically driven fluid valve is a direct-control electromagnetically driven fluid valve. More specifically, the direct-control electromagnetically driven fluid valve is a direct-control electromagnetically driven hydraulic valve. Since the position of the valve element directly depends on the position of the armature of the electromagnet used to drive the valve element, this method can directly calculate the current position of the valve element when the electromagnet is not driven by determining the position of the armature. Therefore, a separate position sensor is not required to detect the position of the valve element.

[0051] Furthermore, a method for determining the valve component position of an electromagnetically driven fluid valve is provided to solve the above-mentioned problem, wherein the electromagnetically driven fluid valve includes a valve component, a first electromagnet for driving the valve component and having a first coil and a first armature, and a second electromagnet that operates complementaryly to the first electromagnet and has a second coil and a second armature; the method includes the following steps:

[0052] Identify the undriven electromagnet of the electromagnetically driven fluid valve;

[0053] The position of the armature of the unelectrified electromagnet is determined by the method according to the present invention; and

[0054] The position of the valve is calculated based on the position of the armature of the undriven electromagnet.

[0055] Specifically, this electromagnetically driven fluid valve is a direct-control electromagnetically driven fluid valve. More specifically, the direct-control electromagnetically driven fluid valve is a direct-control electromagnetically driven hydraulic valve. In the case where the electromagnetically driven fluid valve has two electromagnets for driving the valve element, one of these two complementary electromagnets is typically not driven. Therefore, by using this method for each undriven electromagnet, the position of the armature and the position of the valve element can be continuously determined. Thus, a separate position sensor is unnecessary to detect the position of the valve element.

[0056] Furthermore, a fluid system is provided to solve the above-mentioned problems. The system includes an electromagnetically driven fluid valve and an electronic control unit. The electromagnetically driven fluid valve includes a valve element and an electromagnet, the electromagnet having a coil and an armature, and is used to drive the valve element. Therefore, the electronic control unit is suitable for executing the above-described inventive method for determining the valve element position when the electromagnet is not driven.

[0057] Specifically, the fluid system is a hydraulic system. Specifically, the electromagnetically driven fluid valve is a direct-acting electromagnetically driven fluid valve. Specifically, the direct-acting electromagnetically driven fluid valve is a direct-acting electromagnetically driven hydraulic valve. Such a direct-acting electromagnetically driven fluid valve has only one electromagnet for driving the valve element, and when the electromagnet is not driven, the valve element is normally in the end position. Therefore, the electronic control unit can detect the end position of the valve element by implementing the method according to the invention without using a separate position sensor.

[0058] Furthermore, a fluid system with an electromagnetically driven fluid valve and an electronic control unit is provided to address the aforementioned problems. The electromagnetically driven fluid valve includes: a valve element; a first electromagnet for driving the valve element and having a first coil and a first armature; and a second electromagnet operating complementaryly to the first electromagnet and having a second coil and a second armature. Therefore, the electronic control unit is suitable for performing the aforementioned method for determining the valve element position.

[0059] Specifically, the fluid system is a hydraulic system. Specifically, the electromagnetically driven fluid valve is a direct-acting electromagnetically driven fluid valve. Specifically, the direct-acting electromagnetically driven fluid valve is a direct-acting electromagnetically driven hydraulic valve. In such a direct-acting electromagnetically driven fluid valve with two complementary electromagnets, one of the two electromagnets is normally not driven. Therefore, by implementing the method according to the invention, the electronic control unit can continuously determine the position of the armature, thereby determining the position of the valve element of each undriven electromagnet, without the need for a separate position sensor. Attached Figure Description

[0060] The present invention will now be explained in more detail with reference to the embodiments shown in the accompanying drawings. In the drawings:

[0061] Figure 1 A first fluid system is shown, which includes a first directly controlled electromagnetically driven fluid valve according to a first embodiment of the present invention;

[0062] Figure 2 A second fluid system is shown, which includes a second direct-control electromagnetically driven fluid valve according to a second embodiment of the present invention;

[0063] Figure 3 A schematic diagram of two current curves varying over time is shown to illustrate the first method according to the invention; and

[0064] Figure 4 A schematic diagram of two current curves varying over time is shown to illustrate the second method according to the invention. Detailed Implementation

[0065] Figure 1 A first fluid system 10 according to the invention is shown, comprising an electromagnetically driven fluid valve 11 and an electronic control unit 12. The first fluid system 10 is a first hydraulic system 10, and the electromagnetically driven fluid valve 11 is a direct-acting electromagnetically driven hydraulic valve 11, i.e., a 4 / 3 short-pipe valve configured as a metering valve. The electromagnetically driven fluid valve 11 is known to include a valve element 15 and a first electromagnet 13 and a second electromagnet 14 for actuating the valve element; in this embodiment, the valve element 15 is a spool valve piston. The first electromagnet 13 is known to include a first coil and a first armature. The second electromagnet 14 is known to include a second coil and a second armature. The second electromagnet 14 operates in a complementary manner to the first electromagnet 13. The electronic control unit 12 is adapted to perform the method according to the invention to determine the position of the valve element of the electromagnetically driven fluid valve 11, which will be described in detail below.

[0066] The electronic control unit 12 includes a first current sensor for measuring the current in the first coil of the first electromagnet 13, and a second current sensor for measuring the current in the second coil of the second electromagnet 14. Furthermore, the electronic control unit 12 includes an electromagnet control unit that controls the first electromagnet 13 and the second electromagnet 14 via a power supply voltage. Since how the electronic control unit 12 controls the first electromagnet 13 and the second electromagnet 14 is already generally known, it will not be discussed in detail here.

[0067] Figure 2 A second fluid system 20 according to the present invention is shown, which has an electromagnetically driven fluid valve 21 and an electronic control unit 22. The second fluid system 20 is a second hydraulic system 20, and the electromagnetically driven fluid valve 21 is a direct-control electromagnetically driven hydraulic valve 21, i.e., a 2 / 2-seat valve configured as a switching valve. The electromagnetically driven fluid valve 21 is known to include a valve element 25 and an electromagnet 23 for driving the valve element; in this embodiment, the valve element 25 is a valve cone. The electromagnet 23 is known to include a coil and an armature.

[0068] The electronic control unit 22 includes a current sensor and an electromagnet control unit. The current sensor measures the current in the coil of the electromagnet 23, and the electromagnet control unit controls the electromagnet 23 via a power supply voltage. Since how the electronic control unit 22 controls the electromagnet 23 is already generally known, it will not be discussed in detail here.

[0069] Reference Figure 1 and Figure 3 The following describes a method according to the invention for determining the valve position of an electromagnetically driven fluid valve 11 in a first fluid system 10, the method being executed by an electronic control unit 12.

[0070] First, the electronic control unit 12 identifies the undriven electromagnets in the electromagnetically driven fluid valve 11. Therefore, the electronic control unit 12 can determine whether the first electromagnet 13 or the second electromagnet 14 is currently not energized to drive the valve components of the electromagnetically driven fluid valve 11. When the electronic control unit 12 determines which of the two electromagnets 13 and 14 is undriven, it determines the position of the armature of that undriven electromagnet. For the method of determining the armature position of an undriven electromagnet according to the present invention, it is not important whether it is the first electromagnet 13 or the second electromagnet 14 that is undriven; therefore, in the following text, the undriven electromagnet will be collectively referred to as electromagnets 13 and 14.

[0071] To determine the position of the armature of electromagnets 13 and 14, the electronic control unit 12 applies a current curve to the coils of electromagnets 13 and 14, which is approximately lower than the minimum drive current of electromagnets 13 and 14. When the current in the coils of electromagnets 13 and 14 follows the current curve, the electronic control unit 12 determines the characteristic curve of electromagnets 13 and 14. Based on this characteristic curve, the electronic control unit 12 calculates the position of the armature of electromagnets 13 and 14.

[0072] Reference Figure 3 As can be seen, the electronic control unit 12 initially sets the current in the coils of electromagnets 13 and 14 to a first limited current value I1 during the first time interval t1-t2. The first limited current value I1 is lower than the minimum drive current of electromagnets 13 and 14. For example, if the minimum drive current of electromagnets 13 and 14 is 500 mA, then the first limited current value I1 can be 150 mA. In this case, the current can be set to the first limited current value I1 through rapid control, thereby making the first time interval t1-t2 as short as possible. To this end, the electromagnet control unit of the electronic control unit 12 switches the power supply voltage without a clock until the current in the coils of electromagnets 13 and 14 reaches the first limited current value I1. Alternatively, the first limited current value I1 can be set without rapid control.

[0073] Next, the electronic control unit 12 adjusts the current in the coils of electromagnets 13 and 14 to a first predetermined current value I1 within the second time interval t2-t3. This current is controlled by pulse width modulation. It is conceivable that the step of setting the current to the first predetermined current value I1 can be incorporated as part of the pulse width modulation control, omitting the aforementioned rapid control steps. This would not only prolong the first time interval t1-t2 but also reduce the measurement speed for determining the armature position of electromagnets 13 and 14.

[0074] according to Figure 3 The characteristic curves in the first method shown include compensation characteristics and positional characteristics.

[0075] The electronic control unit 12 determines the compensation characteristics of electromagnets 13 and 14 during the second time interval t2-t3. Specifically, the electronic control unit 12 can determine the temperature-dependent compensation characteristics, which in this example is the copper resistance of the coils of electromagnets 13 and 14. To this end, the electronic control unit 12 determines the average voltage of electromagnets 13 and 14 during the second time interval t2-t3, which is necessary to control the current in the coils of electromagnets 13 and 14 to a first defined current value I1. Furthermore, the electronic control unit 12 determines the average current in the coils of electromagnets 13 and 14 during the second time interval t2-t3. Therefore, the electronic control unit 12 can determine the first defined current value I1 as the average current in the coils of electromagnets 13 and 14, or measure the average current during the second time interval t2-t3 using either the first current sensor or the second current sensor and take their average. Finally, the electronic control unit 12 calculates the compensation characteristics based on the average voltage and average current. Therefore, in this case, the electronic control unit 12 can calculate the copper resistance in the coils of electromagnets 13 and 14 by dividing the average voltage passing through the electromagnets 13 and 14 by the average current in the coils of the electromagnets 13 and 14 according to Ohm's law.

[0076] To determine the average voltage of the electromagnets, the electronic control unit 12 measures the power supply voltage during the second time interval t2-t3 and multiplies the measured power supply voltage by the duty cycle of the pulse width modulation. Alternatively, the electronic control unit 12 may also include a voltage sensor that directly measures the voltage of the electromagnets 13 and 14 and takes their average value during the second time interval t2-t3 to determine the average voltage of the electromagnets.

[0077] Therefore, the electronic control unit 12 has determined the compensation characteristics of electromagnets 13 and 14, that is, the copper resistance of the coils of electromagnets 13 and 14 in the second time interval t2-t3.

[0078] Next, the electronic control unit 12 cuts off the current in the coils of electromagnets 13 and 14 during the third time interval t3-t4 / t4'. Therefore, during the third time interval t3-t4 / t4', electromagnets 13 and 14 are in an active free-running mode, and due to the copper resistance in the coils of electromagnets 13 and 14, the current in electromagnets 13 and 14 is significantly reduced. The energy stored in electromagnets 13 and 14 depends primarily on their inductance. The inductance, in turn, depends on the offset of the armature of electromagnets 13 and 14 within the coil.

[0079] During the third time interval t3-t4 / t4', the electronic control unit determines the position characteristics of electromagnets 13 and 14. Specifically, the electronic control unit determines the position characteristics of electromagnets 13 and 14 as a function of temperature and inductance, that is, the rate of current decrease in the coils of electromagnets 13 and 14.

[0080] To determine the position characteristics, the electronic control unit 12 detects the first moments T1 and T1' when the current in the coils of electromagnets 13 and 14 reaches the second limited current value I2. Furthermore, the electronic control unit 12 detects the second moments T2 and T2' when the current in the coils of electromagnets 13 and 14 reaches the third limited current value I3, where the third limited current value I3 is lower than the second limited current value I2. Finally, the electronic control unit 12 calculates the position characteristics based on the time difference between the second moments T2 and T2' and the first moments T1 and T1', and the current difference between the second limited current value I2 and the third limited current value I3.

[0081] like Figure 3 As shown, the current difference between the second limiting current value I2 and the third limiting current value I3 remains constant so that there is a comparable reference variable. On the other hand, the time difference between the second time T2, T2' and the first time T1, T1' depends on the inductance of electromagnets 13 and 14, and therefore also depends on the position of the armature in the coil of electromagnets 13 and 14.

[0082] Figure 3 Two curves are shown with the armature in different positions. In the solid curve, the inductance of electromagnets 13 and 14 is lower than in the dashed curve. This is why the current decreases faster in the third time interval t3-t4 in the solid curve than in the third time interval t3-t4' in the dashed curve. Figure 3 In the figure, it is still difficult to distinguish the first moment T1 of the solid curve and the first moment T1' of the dashed curve, but it can be observed from the figure that the dashed curve reaches the second limiting current value I2 later than the solid curve. On the other hand, the second moment T2 of the solid curve is significantly earlier than the second moment T2' of the dashed curve.

[0083] Based on the compensation characteristics, the copper resistance and position characteristics of the coils of electromagnets 13 and 14, and the rate of current drop in the coils of electromagnets 13 and 14, the electronic control unit 12 can now calculate the position of the armature of electromagnets 13 and 14.

[0084] Finally, the electronic control unit 12 can calculate the position of the valve component of the electromagnetically driven fluid valve 11 based on the position of the armature of the electromagnets 13 and 14.

[0085] After the electronic control unit 12 completes the calculation, it repeats the above process steps. From Figure 3As can be seen, for example, when the current in the coils of electromagnets 13 and 14 reaches the fourth current value I4, the electronic control unit 12 begins to repeat the above process steps. The fourth current value I4 is variable, specifically depending on the delay of the electronic control unit 12 after detecting the second moment T2 / T2' and the subsequent calculation steps. Even Figure 3 and Figure 4 The fourth current value I4 of the two curves shown is consistent, but technicians know that the fourth current value I4 of the two curves can be different.

[0086] In the direct-control electromagnetically driven fluid valve 11, the position of the valve element is linearly related to the position of the first armature in the first coil of the first electromagnet 13, and similarly linearly related to the position of the second armature in the second coil of the second electromagnet 14. Therefore, by determining the position of the armature of each undriven electromagnet 13, 14, the position of the valve element of the electromagnetically driven fluid valve 11 can be continuously determined without the need for a separate position sensor.

[0087] The electronic control unit 22 of the second fluid system 20 also performs the method according to the invention to determine the position of the valve element of the electromagnetically driven fluid valve 21. This method differs from that performed by the electronic control unit 12 because the electromagnetically driven fluid valve 21 includes only one electromagnet 23, so the electronic control unit 22 does not need to determine which electromagnet is not driven. Therefore, the electronic control unit 22 only performs the method according to the invention to determine the position of the valve element of the electromagnetically driven valve 21 when the electromagnet 23 is not driven.

[0088] In the second fluid system 20, the method according to the invention therefore involves monitoring the end position of the electromagnetically driven fluid valve 21. When the electromagnet 23 is not actuated, the valve is essentially spring-backed to its end position by the spring element. However, for this type of fluid valve, contamination or other disturbances can prevent the valve from being fully closed. Therefore, by performing the method for determining the valve position according to the invention, the electronic control unit 22 can, for example, detect that the valve is not fully closed even when the electromagnet 23 is not actuated, and accordingly warn the user or automatically activate safety measures.

[0089] Figure 4 Two current curves are shown to illustrate a second alternative method according to the invention for determining the position of the armature of an electromagnet. From Figure 4 It can be seen that this alternative method is similar to the above-mentioned reference method. Figure 3 The methods described are different. Figure 3The first time interval t1-t2 and the second time interval t2-t3 are combined here to form the first time interval t1 / t1'-t3. As for the determination of the third interval t3-t4 / t4' and its positional characteristics, the two methods are identical. Therefore, the differences will only be discussed below concerning the first time interval t1 / t1'-t3.

[0090] according to Figure 4 The alternative method can also be applied to the first fluid system 10 and the second fluid system 20. Therefore, the following description of the first fluid system 10 can be directly transferred to the second fluid system 20.

[0091] According to this alternative method, the applied current curve includes: the electronic control unit 12 applies a controlled voltage to the coils of electromagnets 13 and 14 during the first time interval t1 / t1'-t3 until a first predetermined current value I1 is reached. Subsequently, similar to... Figure 3 In the aforementioned program, the electronic control unit 12 cuts off the current in the coils of electromagnets 13 and 14 during the third time interval t3-t4 / t4' and determines the position characteristics of electromagnets 13 and 14.

[0092] according to Figure 4 The characteristic curves in the method shown include the positional characteristics and the alternative compensation characteristics described above.

[0093] In the second time interval t1 / t1'-t3, the electronic control unit 12 determines the alternative compensation characteristic. In this case, the electronic control unit 12 determines the current growth rate as the compensation characteristic in the first time interval t1 / t1'-t3. Therefore, in a similar but reverse manner to the determination of the current decrease rate during the third time interval t3-t4 / t4' described above, the current growth rate during the first time interval t1 / t1'-t3 is determined based on the third limited current value I3 and the second limited current value I2.

[0094] Therefore, the third moments T3 and T3' when the current in the coils of electromagnets 13 and 14 reaches the third limited current value I3, and the fourth moments T4 and T4' when the current in the coils of electromagnets 13 and 14 reaches the second limited current value I2 can be detected. Then, based on the time difference between the fourth moment T4 and T4' and the third moment T3 and T3', and the current difference between the second limited current value I2 and the third limited current value I3, the electronic control unit 12 can calculate the current growth rate in the coils of electromagnets 13 and 14.

[0095] Figure 4 It also shows the relationship with Figure 3The two curves show similar armatures in different positions. It can be clearly seen that the current growth rate also depends on the armature's position within the coils of electromagnets 13 and 14. In the solid curve, the inductance of electromagnets 13 and 14 is lower than in the dashed curve. This is why the current growth rate in the second time interval t1-t3 of the solid curve is faster than the current growth rate in the first time interval t1'-t3 of the dashed curve.

[0096] The temperature dependence of the current increase rate is opposite to that of the current decrease rate. Therefore, the current increase rate in the coils of electromagnets 13 and 14 can be used as a temperature compensation characteristic.

[0097] List of reference numerals

[0098] 10 First Fluid System / First Hydraulic System

[0099] 11 Electromagnetic Driven Fluid Valve / Direct-Control Electromagnetic Driven Hydraulic Valve

[0100] 12 Electronic Control Unit

[0101] 13 First Electromagnet

[0102] 14 Second Electromagnet

[0103] 15 valve components / slide valve piston

[0104] 20 Second Fluid System / Second Hydraulic System

[0105] 21 Electromagnetic Driven Fluid Valve / Direct-Controlled Electromagnetic Driven Hydraulic Valve

[0106] 22 Electronic Control Unit

[0107] 23 Electromagnet

[0108] 25 valve / valve cone

[0109] I1 First limited current value

[0110] I2 Second limiting current value

[0111] I3 Third Limiting Current Value

[0112] I4 Fourth Current Value

[0113] t1-t2 First time interval

[0114] t2-t3 Second time interval

[0115] The third time interval t3-t4 / t4'

[0116] T1, T1' First Moment

[0117] T2, T2' Second Time

[0118] T3, T3' Third Time

[0119] T4, T4' Fourth Moment

Claims

1. A method for determining the position of the armature of an electromagnet (13, 14, 23), the electromagnet (13, 14, 23) comprising a coil and an armature, the method being performed by an electronic control unit (12, 22), the method comprising the following steps: Apply current curves to the coils of the electromagnets (13, 14, 23), wherein the current curves are approximately lower than the minimum drive current of the electromagnets (13, 14, 23). Determine the characteristic curve of the electromagnet; and The position of the armature of the electromagnet (13, 14, 23) is calculated based on the characteristic curve. The application of the current curve includes the following steps: During the first time interval (t1-t2), the current in the coil of the electromagnet (13, 14, 23) is set to a first limited current value (I1). During the second time interval (t2-t3), the current in the coil of the electromagnets (13, 14, 23) is adjusted to the first defined current value (I1); and During the third time interval (t3-t4, t3-t4'), the current in the coil of the electromagnet (13, 14, 23) is cut off; Furthermore, determining the characteristic curve includes the following steps: Determine the compensation characteristics of the electromagnets (13, 14, 23) in the second time interval (t2-t3); and Determine the positional characteristics of the electromagnets (13, 14, 23) in the third time interval (t3-t4, t3-t4').

2. The method of claim 1, wherein, The compensation characteristics of the electromagnet are the temperature-dependent compensation characteristics of the electromagnets (13, 14, 23).

3. The method of claim 2, wherein, The temperature-dependent compensation characteristic of the electromagnets (13, 14, 23) is the copper resistance of the coil of the electromagnets (13, 14, 23).

4. The method of claim 1, wherein, The positional characteristics of the electromagnets (13, 14, 23) are the positional characteristics of the electromagnets (13, 14, 23) that vary with temperature and inductance.

5. The method of claim 4, wherein, The positional characteristics of the electromagnets (13, 14, 23) that vary with temperature and inductance are the rate of decrease of the current in the coil of the electromagnets (13, 14, 23).

6. The method of claim 1, wherein, Adjusting the current in the coil of the electromagnet (13, 14, 23) to the first defined current value (I1) within the second time interval (t2-t3) is accomplished by pulse width modulation.

7. The method of claim 6, wherein, Determining the compensation characteristics of the electromagnets (13, 14, 23) includes: Determine the average voltage passing through the electromagnets (13, 14, 23); Determine the average current in the coil of the electromagnet (13, 14, 23); and The compensation characteristics are calculated based on the average voltage and the average current.

8. The method of claim 7, wherein, Determining the average voltage passing through the electromagnets (13, 14, 23) includes: Measure the power supply voltage during the second time interval (t2-t3); and Multiply the measured power supply voltage by the duty cycle of the pulse width modulation.

9. The method of claim 1, wherein, Determining the compensation characteristics of the electromagnets (13, 14, 23) includes: Determine the average voltage passing through the electromagnets (13, 14, 23); Determine the average current in the coil of the electromagnet (13, 14, 23); and The compensation characteristics are calculated based on the average voltage and the average current.

10. The method of claim 9, wherein, Determining the average voltage passing through the electromagnets (13, 14, 23) includes: Measure the voltage passing through the electromagnets (13, 14, 23) during the second time interval (t2-t3); and The average value of the measured voltages of the electromagnets (13, 14, 23) is calculated.

11. The method of claim 9, wherein, Determining the average current in the coil of the electromagnets (13, 14, 23) includes: Measure the current in the coil of the electromagnet (13, 14, 23) during the second time interval (t2-t3); and The average value of the measured current in the coil of the electromagnet (13, 14, 23) is calculated.

12. The method of claim 9, wherein, Determining the average current in the coil of the electromagnet (13, 14, 23) includes defining the first defined current value (I1) as the average current in the coil of the electromagnet (13, 14, 23).

13. A method for determining the position of the armature of an electromagnet (13, 14, 23), the electromagnet (13, 14, 23) comprising a coil and an armature, the method being performed by an electronic control unit (12, 22), the method comprising the following steps: Apply current curves to the coils of the electromagnets (13, 14, 23), wherein the current curves are approximately lower than the minimum drive current of the electromagnets (13, 14, 23). Determine the characteristic curve of the electromagnet; and Calculate the position of the armature of the electromagnet (13, 14, 23) based on the characteristic curve. The application of the current curve includes the following steps: During the first time interval (t1-t3, t1'-t3), an adjustment voltage is applied to the coil of the electromagnet (13, 14, 23) until a first predetermined current value (I1) is reached; and During the third time interval (t3-t4, t3-t4'), the current in the coil of the electromagnet (13, 14, 23) is cut off; Furthermore, determining the characteristic curve includes the following steps: Determine the compensation characteristics of the electromagnets (13, 14, 23) in the first time interval (t1-t3, t1'-t3); and Determine the positional characteristics of the electromagnets (13, 14, 23) in the third time interval (t3-t4, t3-t4').

14. The method of claim 13, wherein, The compensation characteristic is the rate of current growth in the coil of the electromagnet (13, 14, 23).

15. The method according to claim 1 or 13, wherein, Determining the positional characteristics includes: The first moment (T1, T1') when the current in the coil of the electromagnet (13, 14, 23) reaches the second limited current value (I2) is detected. The detection occurs at a second moment (T2, T2') when the current in the coil of the electromagnet (13, 14, 23) reaches a third limiting current value (I3) that is lower than the second limiting current value (I2); and The position characteristics are calculated based on the time difference between the second time point (T2, T2') and the first time point (T1, T1') and the current difference between the second limited current value (I2) and the third limited current value (I3).

16. The method of claim 1 or 13, wherein, The electromagnets (13, 14, 23) are electromagnets for electromagnetically driven fluid valves (11, 21).

17. A method of determining the position of a valve member of an electromagnetically driven fluid valve (21), wherein, The electromagnetically driven fluid valve (21) includes the valve element and an electromagnet (23) for driving the valve element. The electromagnet (23) includes a coil and an armature. The method includes the following steps: The position of the armature of the electromagnet (23) is determined by the method according to claim 1 or 13; and The position of the valve is calculated based on the position of the armature of the electromagnet (23).

18. A method of determining the position of a valve member of an electromagnetically driven fluid valve (11), wherein, The electromagnetically driven fluid valve (11) includes the valve element, a first electromagnet (13) for driving the valve element and having a first coil and a first armature, and a second electromagnet (14) that operates complementaryly to the first electromagnet (13) and has a second coil and a second armature; the method includes the following steps: Determine the undriven electromagnets (13, 14) of the electromagnetically driven fluid valve (11). The position of the armature in the undriven electromagnet (13, 14) is determined by the method according to claim 1 or 13; and The position of the valve is calculated based on the position of the armature of the undriven electromagnet (13, 14).

19. A fluid system (20) comprising: The electromagnetically driven fluid valve (21) and electronic control unit (22) are provided, wherein the electromagnetically driven fluid valve (21) includes a valve element (25) and an electromagnet (23) for driving the valve element (25), the electromagnet (23) including a coil and an armature; The electronic control unit (22) is configured to perform the method according to claim 16 when the electromagnet (23) is not driven.

20. A fluid system (10) comprising: The electromagnetically driven fluid valve (11) and electronic control unit (12) include a valve element (15), a first electromagnet (13) for driving the valve element (15) and having a first coil and a first armature, and a second electromagnet (14) that operates complementary to the first electromagnet (13) and has a second coil and a second armature. The electronic control unit (12) is adapted to perform the method according to claim 17.

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