SOLENOID VALVE ACTUATOR

Abstract

Solenoid valve actuator device (18) wherein a hysteresis setpoint or hysteresis time is set on the basis of a first difference value between an extreme value of a hysteresis value of a solenoid valve current in a peak hold section of the solenoid valve current and a hysteresis setpoint, comprising: a control or regulating device (16) which issues an opening / closing command to a first switching element (2) to switch on / off a drive current (I1) supplied to the solenoid valve (1), and a storage device (13) which stores setpoints of the extreme values ​​of the hysteresis and a setpoint of the time interval between the extreme values ​​of the hysteresis, wherein the control device (16) generates a hysteresis of the drive current (I1) by repeatedly switching the first switching element (2) on and off during a first peak holding period after a current value of the drive current (I1) has reached a first current level, and the control device (16) sets extreme values ​​of the hysteresis or sets a time interval between the extreme values ​​of the hysteresis such that the hysteresis of the drive current (I1) falls into a predetermined range from the first current level, characterized by the fact that the control device (16) calculates a first gradient of the hysteresis of the drive current (I1) using the extreme values ​​of the hysteresis of the drive current (I1) and the time interval between the extreme values, and calculates a second gradient of the hysteresis using the setpoints of the extreme values ​​of the hysteresis and the setpoint of the time interval between the extreme values ​​of the hysteresis, and the control device (16) adjusts the extreme values ​​of the hysteresis or the time interval between the extreme values ​​of the hysteresis such that, in a case where the second difference value is not within the range of a predetermined gradient threshold, a second difference value between the first gradient and the second gradient falls within the range of the predetermined gradient threshold.

Description

Technical field

[0001] The present invention relates to a solenoid valve actuator device that controls a current flowing through a solenoid valve in order to open and close the solenoid valve. State of the art

[0002] A solenoid valve that injects fuel into each cylinder of an internal combustion engine comprises a solenoid valve that is opened and closed by energizing and deactivating a solenoid coil. A solenoid valve actuator that drives the solenoid valve generally comprises a first switching element that increases a battery voltage and applies the increased battery voltage to the solenoid valve, a second switching element that applies the battery voltage to the solenoid valve according to an injection signal, and a third switching element that is in an energized state for an entire range of an injection period of the solenoid valve.

[0003] The solenoid valve actuator applies an increased voltage to the solenoid valve synchronously with the injection signal to open it quickly. Furthermore, even with high-pressure fuel, a constant current is maintained through the solenoid valve for a predetermined time to minimize fluctuations in its opening. Afterward, to maintain the solenoid valve in a predetermined open state, the increased voltage is interrupted and the battery voltage is applied. Subsequently, the constant current is maintained through the solenoid valve using the battery voltage until the end of an actuation period. A constant-current control unit, which directs the constant current through the solenoid valve, performs hysteresis control.-regulation in which a switching element is turned on when a current value is equal to or lower than a lower limit threshold, and the switching element is turned off when the current value is equal to or higher than an upper limit threshold.

[0004] A solenoid valve actuator described in patent literature 1 measures a maximum and a minimum value during the constant current control of a solenoid valve and sets an upper limit value and a lower limit value for a constant current such that the difference between the maximum and minimum values ​​falls within a standard range. Furthermore, DE 10 2013 222 326 A1 (see patent document 2) describes a fuel injection control device for an internal combustion engine, wherein a coil current is amplified to a first setpoint and maintained there, and wherein this first setpoint can be changed according to the operating state of the internal combustion engine. This allows the amplification rate of the electromagnetic attraction force to be adjusted. US 6,571,773 B1 (see patent document 2) describes a fuel injection control device for an internal combustion engine, wherein a coil current is amplified to a first setpoint and maintained there, and wherein this first setpoint can be changed according to the operating state of the internal combustion engine.Patent document 3 describes an electromagnetic fuel injection system for internal combustion engines, which dynamically adjusts the peak current and switching time to changes in battery voltage, resistance, and fuel pressure. This enables precise fuel injection under various engine operating conditions and improves efficiency and performance. Finally, JP 2013-258406A (see patent document 4) describes a control device for inductive loads, particularly for solenoid valves in automatic transmissions, which controls the fluctuation period of the target current value by means of PWM control so that it is greater than the fluctuation period of the actual current. This allows for minimizing the sliding resistance of the linear solenoid while simultaneously adapting the current ripple to the detectable range of the current sensing circuit. List of literature Patent literature Patent literature 1: JP 2014 - 169 652 A Patent literature 2: DE 10 2013 222 326 A1 Patent literature 3: US 6,571,773 B1 Patent literature 4: JP 2013 - 258 406 A Summary of the invention: Technical problem

[0005] In the solenoid valve actuator, there is an operating delay in an electronic component that provides the constant current control of the solenoid valve. Therefore, a delay occurs from the moment the current reaches an upper or lower threshold value until the switching element is turned on or off. Consequently, even after reaching the upper or lower threshold value, the current can continue to change in the same direction, potentially exceeding the threshold. The threshold overrun can be defined as the error between an actual extreme value and the threshold value of the solenoid valve current. Furthermore, fluctuations in the threshold overrun can also occur due to variations in the coil resistance of the electronic component or the solenoid valve itself that provides the constant current control.

[0006] Furthermore, in recent years a pressure booster for the solenoid valve has been developed to comply with emissions regulations and reduce fuel consumption. Therefore, the current is held for a predetermined time, with the increased voltage being used to open the valve, ensuring stable valve opening even at high voltage. At this point, the current is regulated by the increased voltage, so any deviation in the threshold exceedance tends to increase. It was therefore necessary to control the hysteresis value of the solenoid valve current of the solenoid valve actuator with greater accuracy than conventional methods.

[0007] In a technology described in patent literature 1, in order to suppress hysteresis fluctuations caused by the electrical properties of a coil current path, the electrical properties are measured, and the upper and lower thresholds corresponding to the measured values ​​are then determined from a pre-existing threshold map. This method serves to suppress hysteresis fluctuations caused by the electrical properties of the coil current path, and it is assumed that it is difficult to deal with hysteresis fluctuations caused by other factors.

[0008] The present invention was made in view of the above circumstance, and one object of the present invention is to provide a solenoid valve actuator device that is able to precisely control a hysteresis value of an actuator current for driving a solenoid valve. Solution to the problem

[0009] The problem is solved by the features of claim 1. Specific embodiments are described in the dependent claims. Advantageous effects of the invention

[0010] According to the solenoid valve actuator device of the present invention, the setpoint of the hysteresis or the temporal width of the hysteresis is controlled depending on how much a hysteresis value of the drive current for driving a solenoid valve deviates from the setpoint, so that the hysteresis can be precisely controlled. Brief description of the drawings Fig. Figure 1 is a graphical configuration representation of a solenoid valve actuator device 18 according to a first embodiment. Fig. Figure 2 is a timing diagram for describing the switching on / off processes of each switching element. Fig. Figure 3 is a graphical representation to describe the influence of a delay of a drive current I1. Fig. Figure 4 is a flow diagram illustrating a process in which the solenoid valve actuator 18 prevents a hysteresis of the actuator current I1 from exceeding a threshold value. Fig. 5A is an example where a valve opening holding section is configured in multiple stages. Fig. 5B is an example where a drive current I1 is not kept near a valve opening current in a valve opening section AR1. Fig. Figure 6 is a flow diagram illustrating a different process in which a solenoid valve actuator 18 prevents a hysteresis of the actuator current I1 from exceeding a threshold value. Fig. Figure 7 is a flowchart illustrating a further process in which a solenoid valve actuator 18 prevents a hysteresis of the actuator current I1 from exceeding a threshold value. Fig. Figure 8 is a graphical representation illustrating a specific example of a time point for setting an extreme value of a hysteresis of a drive current I1. Fig. 9 is an example where the hysteresis slope of the drive current I1 deviates from an original setting. Description of embodiments: First embodiment: Configuration of the device

[0011] Fig. Figure 1 is a graphical configuration representation of a solenoid valve actuator device 18 according to a first embodiment of the present invention.

[0012] The solenoid valve actuator 18 controls the fuel injection into each cylinder of a combustion engine or diesel engine by actuating a solenoid valve 1. The solenoid valve actuator 18 controls the fuel injection timing and quantity into each cylinder by regulating the excitation start time and duration of the solenoid valve 1. For example, in the case of a four-cylinder engine, the fuel injection of the solenoid valves located in each of the four cylinders is controlled.Solenoid valve 1 is a normally closed solenoid valve, and when solenoid valve 1 is energized, a valve body (not illustrated) moves into a valve opening position so that fuel is injected, and when the energization of solenoid valve 1 is interrupted, the valve body returns to an original valve closing position so that fuel injection is stopped.

[0013] The solenoid valve actuator 18 comprises a first switching element 2, a second switching element 3, a third switching element 4, a current sensing resistor 5, a freewheeling diode 6, protection diodes 7 to 9, batteries 10 and 11, and a system unit 17. The system unit 17 further comprises a drive signal generation unit 12, a storage device 13, a comparator 15, and a control unit 16. The battery 10 can, for example, be a voltage obtained by increasing a voltage supplied by the battery 11. A setpoint 14 is a comparison reference value used by the comparator 15 and stored in the storage device 13.

[0014] The first switching element 2 applies a voltage supplied by battery 10 to solenoid valve 1. The second switching element 3 applies a voltage supplied by battery 11 to solenoid valve 1. The third switching element 4 remains energized throughout the entire injection period. These switching elements can be configured, for example, by a metal-oxide-semiconductor (MOS) transistor.

[0015] The control unit 16 outputs a drive signal T1 to the drive signal generation unit 12 to actuate the solenoid valve 1. The drive signal T1 has a high level (H) during the period for controlling the solenoid valve 1 to be opened (hereinafter referred to as the actuation period) and a low level (L) during the period for controlling the solenoid valve 1 to be closed (hereinafter referred to as the non-actuation period). In a case where multiple solenoid valves 1 are present, the control unit 16 selects one solenoid valve 1 to be energized and then outputs the drive signal T1 to the selected solenoid valve 1. The control unit 16 can be configured, for example, by a microcomputer.The actuator signal generation unit 12 outputs actuator signals to the first switching element 2, the second switching element 3, and the third switching element 4 based on the actuator signal T1 from the control unit 16. The following describes a valve opening section (second peak holding period), a valve opening maintenance section (first peak holding period), and a valve closing section of the solenoid valve 1.

[0016] In the valve opening section, a peak current is supplied to solenoid valve 1 to quickly open it at the start of a preset actuation period. The control unit 16 outputs the actuation signal T1 to the actuation signal generation unit 12 to actuate solenoid valve 1 only for a predetermined period. The actuation signal generation unit 12 supplies the peak current to solenoid valve 1 and thus outputs an actuation signal T2 to the first switching element 2. The first switching element 2 is controlled to be switched on and off depending on the actuation signal T2. At this point, the third switching element 4 is switched on depending on an actuation signal T4 output by the actuation signal generation unit 12.

[0017] The solenoid valve actuator 18 transitions from the valve opening section to the valve opening hold section. In the valve opening hold section, the voltage supplied by the battery 11 is applied to the solenoid valve 1 to keep it in an open position. The actuator signal generation unit 12 switches off the actuator signal T2 and outputs an actuator signal T3 to the second switching element 3 to supply the solenoid valve 1 with a valve opening hold current in the valve opening hold section. The second switching element 3 is controlled to switch on and off depending on the actuator signal T3. At this point, the third switching element 4 is switched on depending on the actuator signal T4.

[0018] When a valve closing point is reached in the valve closing section, the control unit 16 switches off the actuator signal T1. When the actuator signal T1 is switched off, the actuator signal generation unit 12 switches off the actuator signals T3 and T4 accordingly. As a result, the back electromotive energy accumulated in the solenoid valve 1 is dissipated.

[0019] Fig. Figure 2 is a timing diagram describing the switching operations of each switching element. First, the operation of the first switching element 2 in a valve opening section AR1 is described. The switching control of the first switching element 2 serves to maintain the actuator current I1 of the solenoid valve 1 near its peak level (constant current control). When the actuator signal T1 is activated, the first switching element 2 is switched on, thus applying a voltage V1 to the solenoid valve 1. When the voltage V1 is applied to the solenoid valve 1, the actuator current I1 gradually increases due to the coil resistance of the solenoid valve 1. When the actuator current I1 reaches an upper threshold value Iha1, the first switching element 2 is switched off, causing the actuator current I1 to decrease. When the actuator current I1 reaches a lower threshold value Iha2, the first switching element 2 is switched on again.In this way, a oscillation width (hysteresis) of the drive current I1 is maintained between the lower limit threshold Iha2 and the upper limit threshold Iha1 in the valve opening section AR1. As a result, the valve opening force of solenoid valve 1 increases such that the solenoid valve 1 opens smoothly, even at high fuel pressure, for example.

[0020] Next, the operation of the second switching element 3 in a valve opening retention section AR2 is described. When the constant current control ends in the valve opening section AR1, the first switching element 2 and the second switching element 3 are switched off, causing the drive current I1 to decrease. When the drive current I1 decreases to a lower limit threshold Ihb2 in the valve opening retention section AR2, the second switching element 3 is switched on, causing the drive current I1 to increase again.

[0021] When the drive current I1 reaches an upper threshold value Ib1, the second switching element 3 is switched off. In this way, a oscillation (hysteresis) of the drive current I1 is maintained between the lower threshold value Ihab and the upper threshold value Ihb1 in the valve opening retention section AR2. As a result, the solenoid valve 1 is held in the open position.

[0022] Due to a fluctuation in the properties of the solenoid valve actuator 18 (for example, the operating characteristics of each switching element), a fluctuation in the coil resistance of the solenoid valve 1, or the like, a change in the actuator current I1 with respect to the operation of each switching element may be delayed. A dotted line in Fig. Figure 2 is an example of such a delay. In particular, if the transition time from the valve opening retention section AR2 to a valve closing section AR3 is delayed, the valve closing time of solenoid valve 1 deviates from a requirement, leading to a deterioration in exhaust emissions or a deterioration in the fuel consumption of an engine device. This is described with reference to Fig. 3 described in more detail.

[0023] Fig. Figure 3 is a graphical representation to describe the influence of a delay in the drive current I1. An example in the valve opening section is illustrated here. The upper part of the Fig. Figure 3 is a waveform of the applied voltage V1 to solenoid valve 1. The middle part of the Fig. Figure 3 is a current waveform in a case where the driving current I1 is not delayed with respect to the applied voltage V1. The lower part of the Fig. Figure 3 is a current waveform in a case where the driving current I1 is delayed with respect to the applied voltage V1.

[0024] In a case where the drive current I1 exhibits a delay, even though the drive current I1 reaches the lower limit threshold Iha2 or the upper limit threshold Iha1, the drive current I1 can continue to change in the same direction and consequently exceed any threshold. Fig. Figure 3 represents an upper limit exceedance value Iha1' and a lower limit exceedance value Iha2', each shown as an example. This is because the drive current I1 exceeds the threshold value, as indicated by the dotted line in Figure 3. Fig. As illustrated in Figure 2, there is a fluctuation or delay in the period required for the transition from the valve opening section AR1 to the valve opening retention section AR2, or in the period required for the transition from the valve opening retention section AR2 to the valve closing section AR3.

[0025] Fig. Figure 4 is a flowchart illustrating a process in which the solenoid valve actuator 18 prevents the hysteresis of the actuator current I1 from exceeding a threshold value. The flowchart of the Fig. Step 4 can be applied to both the valve opening section AR1 and the valve opening retention section AR2. Each step of the Fig. 4 is described below. (Figure 4: Step S1)

[0026] The control unit 16 defines a section in which the drive current I1 is kept at a constant current level (valve opening section AR1 or valve opening retention section AR2 in Fig. 2), as a measuring section. (Figure 4: Step S2)

[0027] The control unit 16 detects an extreme value (for example, Iha1') of the hysteresis of the drive current I1 in the defined measuring section through the current sensing resistor 5. The extreme value measured in this step can be an extreme value (for example, Iha1') on the upper limit threshold side, an extreme value (for example, Iha2') on the lower limit threshold side, or both extreme values. The control unit 16 stores the measured extreme value in the storage device 13 via a current monitoring circuit 19. (Figure 4: Step S3)

[0028] The control unit 16 calculates a comparison value (for example, the difference value Iha1' - Iha1) by comparing the extreme value (for example, Iha1') stored in the storage device 13 in step S2 with the setpoint 14 (for example, Iha1) of the threshold value corresponding to the extreme value using the comparator 15. In this step, the comparison value is not necessarily a difference value, as long as the extreme value and the setpoint can be compared. For example, the comparison value could be a ratio (Iha1' / Iha1). (Figure 4: Step S4)

[0029] The control unit 16 modifies the setpoint 14 of the hysteresis extreme value or a time interval between the hysteresis extreme values ​​such that the subsequent drive current I1 falls within the threshold range according to the comparison value calculated in step S3. If the setpoint 14 is changed, the setpoint 14 is adjusted downwards for an upper limit extreme value and upwards for a lower limit extreme value. If the time interval between the extreme values ​​is changed, the time interval is narrowed. The drive signal generation unit 12 outputs the subsequent drive signals T2 and T3 according to the modified value. (Figure 4: Step S5)

[0030] Control unit 16 repeatedly executes steps S1 to S4 until the comparison value reaches zero or a value less than a predetermined comparison threshold. The flowchart terminates when the comparison value reaches zero or a value less than the predetermined comparison threshold. First embodiment: Summary

[0031] The solenoid valve actuator 18 according to the first embodiment causes the extreme value of the subsequent hysteresis to fall within the range of the setpoint 14 by adjusting the setpoint 14 or the time interval between the extreme values ​​when the extreme value of the hysteresis of the actuator current I1 exceeds the setpoint 14 in a section where the actuator current I1 is kept close to the constant current. As a result, fluctuations (pulsation width) of the actuator current I1, particularly at the end of an excitation period, are reduced, as is fluctuation in the valve closing delay time from the end of the excitation period until the solenoid valve 1 closes. This improves the control accuracy of an injection timing. Improved control accuracy of an injection timing reduces wasted injections.Therefore, the fuel consumption of the engine device can be improved and the deterioration of the exhaust emissions of the engine device can be prevented. Second embodiment

[0032] In the first embodiment, an example has been described in which the drive current I1 is maintained near a valve opening current in the valve opening section AR1 and the drive current I1 is maintained near a valve opening holding current in the valve opening holding section AR2. In a second embodiment of the present invention, it is described that a method similar to that of the first embodiment can be applied to the other temporal change patterns of a drive current I1. A configuration of a solenoid valve drive device 18 is similar to that of the first embodiment.

[0033] Fig. 5A is an example where a valve opening retention section is configured in multiple stages. In a case where the valve opening retention section is configured in multiple stages, as in Fig. As illustrated in Figure 5A, the level of the drive current I1 immediately before the transition to a valve closing section approaches a current level at the point of closure of the solenoid valve, and the solenoid valve 1 can thus transition quickly to a closed state. This means that there is an advantage in that a delay in the valve closing time can be prevented. Also, in each stage of the valve opening maintenance section, similar to the first embodiment, an extreme value of a hysteresis of each valve opening maintenance current is held as a setpoint 14, and the setpoint 14 or a time interval between extreme values ​​can be adjusted so that the drive current i1 falls within a setpoint range of extreme values.

[0034] Fig. 5B is an example where a drive current I1 is not kept close to a valve opening current in a valve opening section AR1. In a case where it is not necessary to keep the drive current I1 close to the valve opening current to gently open the solenoid valve 1, the first switching element 2 can be switched off immediately when the drive current I1 reaches a peak value, as in Fig. Figure 5B illustrates this. Even in this case, the drive current I1 can exceed the setpoint 14 of the extreme value in the valve opening section. Therefore, the setpoint 14 can be adjusted so that the drive current I1 does not exceed the setpoint 14 in the next valve opening section. Third embodiment

[0035] Fig. Figure 6 is a flowchart illustrating another method in which a solenoid valve actuator 18 prevents the hysteresis of an actuator current I1 from exceeding a threshold value. One configuration of the solenoid valve actuator 18 is similar to that of the first and second embodiments. Fig. Step S6 is executed instead of step S5. In step S6, a control unit 16 determines whether steps S1 to S4 have been executed a predetermined number of times. If steps S1 to S4 have not been executed the predetermined number of times, the process returns to step S1, and similar processing is repeated. If steps S1 to S4 have been executed a predetermined number of times, the flowchart ends. The purpose of this flowchart is to simplify processing by limiting the number of repetitions to a predetermined number, for example, in a case where changing the setpoint 14 or the time interval is repeated in a minimum number of times in step S4.

[0036] In a case where the predetermined number of times in step S6 is one, the flowchart of Fig. 6 can be used to make an adjustment so that the drive current I1 falls within the range of the setpoint 14, for example during a shipping inspection at the time of shipment of the solenoid valve actuator 18. Since in this case it is not necessary to use the flowchart of the Fig. 6. To perform the necessary steps after shipping the solenoid valve actuator 18, a storage device 13 can be configured using a one-time read-only memory (ROM) (ROM, into which data can only be written once). This allows the cost of the storage device 13 to be kept low.

[0037] Fig. Figure 7 is a flowchart of another method in which a solenoid valve actuator 18 prevents the hysteresis of an actuator current I1 from exceeding a threshold value. The configuration of the solenoid valve actuator 18 is similar to that of the first and second embodiments. Fig. Step S7 is executed instead of step S5. In step S7, a control unit 16 determines whether or not to terminate the operation of the solenoid valve actuator 18. If the operation of the solenoid valve actuator 18 is not terminated, the process returns to step S1 and a similar procedure is repeated. If the operation of the solenoid valve actuator 18 is terminated, the present flowchart ends. The present flowchart continuously repeats the extreme value setting of the hysteresis of the actuator current I1 while the solenoid valve actuator 18 is in operation. As a result, for example, despite a change in the ambient temperature of the solenoid valve actuator 18, a hysteresis setting is updated so that the actuator current I1 can continue to be controlled with high accuracy. Fourth embodiment

[0038] In a fourth embodiment of the present invention, a specific method for setting an extreme value of a hysteresis of a drive current I1 is described in more detail. The configuration of a solenoid valve actuator 18 is similar to that of the first to third embodiments, so that mainly the details of a method for setting an extreme value are described.

[0039] Fig. Figure 8 is a graphical representation showing a specific example of the timing of setting an extreme value of a hysteresis of a drive current I1. In a case where it is determined that the extreme value of the hysteresis of the drive current I1 exceeds a setpoint 14, a control unit 6 can immediately change the setpoint 14 or an extreme value interval. Fig. 8. The setpoint 14 or the extreme value interval is changed before the drive current reaches the next extreme value in the same valve opening section AR1. As a result, the next extreme value is improved to a certain extent (any exceedance of the extreme value with respect to a threshold is reduced). If the extreme value still exceeds the threshold despite the adjustment, a further adjustment can be made. Fig. Figure 8 illustrates an example where the drive current I1 falls within a threshold range by two adjustments. Similar processing can be performed in a valve opening retention section AR2. A delay of the drive current I1 can be achieved using the method described in Fig. The 8 illustrated procedures can be quickly corrected, and the possibility of a valve closing time deviating can be further reduced.

[0040] Fig. Figure 9 is an example where the slope of the drive current I1's hysteresis deviates from an initial setting. A delay in the drive current I1 can appear as a slope deviation of the hysteresis. The control unit 16 can detect the slope deviation and adjust the slope so that it returns to its original setting. Specifically, the setpoint for the time interval between the extreme values ​​of the hysteresis can be pre-stored in the storage device 13, the slope of the hysteresis can be calculated based on an actual measurement from each of the time intervals between the extreme values ​​of the hysteresis, and the slope of the setpoint can be calculated and adjusted based on the difference between the actual measurement and the setpoint.For example, if the inclination is small, the drive current I1 is delayed, and the time interval between the extreme values ​​is adjusted to become shorter. This is a method of... Fig. 9 can be considered useful in a case where the delay of the drive current I1 does not appear to exceed a threshold. Modifications of the present invention

[0041] The present invention is not limited to the embodiments mentioned above, but includes various modifications. For example, the embodiments mentioned above have been described in detail to provide an easily understandable description of the present invention, and they are not necessarily limited to having all the components described. Furthermore, some of the components of a particular embodiment can be replaced by components of another embodiment, and components of another embodiment can also be added to components of a particular embodiment. In addition, it is possible to add, delete, or replace other components with respect to some of the components of the respective embodiments.

[0042] In the embodiments described above, each of the switching elements 2 to 4 can be a transistor, such as a bipolar transistor, an insulated-gate bipolar transistor (IGBT), or the like. The solenoid valve 1 is not limited to an injector but can, for example, be a solenoid valve of a fuel pump that supplies fuel under pressure. The control unit 16 can be configured to use an application-specific integrated circuit (ASIC) or can be configured to combine a microcomputer and an ASIC.

[0043] In the above embodiments, a maximum or minimum hysteresis value is treated as an extreme value, but instead of the maximum or minimum hysteresis value, an average or RMS value of a current level over a specific time period close to the extreme value can be used. As a result, it is possible to suppress the excessive influence of a transient event, such as a momentary threshold exceedance.

[0044] In the above embodiments, it was described to set the setpoint 14 or the extreme value interval of the hysteresis when the drive current I1 exceeds the threshold, but the expression "exceeds the threshold" mentioned here means that an absolute value of the drive current I1 exceeds an absolute value of any threshold, as is clearly evident from the above description.

[0045] In the above embodiments, the lower limit threshold Iha2, the upper limit threshold Iha1, the lower limit threshold Ihb2, and the upper limit threshold Ihb1 correspond to an example of an “extreme value of a hysteresis” as described in the claims. The valve opening section AR1 and the valve opening retention section AR2 can correspond to an example of a “peak hold time” as described in the claims. Reference symbol list 1 solenoid valve 2 first switching element 3 second switching element 4 third switching element 5 Current sensing resistor 6 Freewheeling diode 7 to 9 protection diode 10 batteries 11 Battery 15 Comparator 16 Control unit 17 System unit 18 Solenoid valve actuator 19 Current monitoring

Claims

[1] A solenoid valve driving device (18), wherein a hysteresis set value or a hysteresis time is set based on a first difference value between an extreme value of a hysteresis value of a solenoid valve current in a peak holding section of the solenoid valve current and a hysteresis set value, comprising: a control or regulating device (16) which outputs an opening / closing command to a first switching element (2) for switching on / off a drive current (I1) supplied to the solenoid valve (1), and a storage device (13) which stores setpoint values of the extreme values of the hysteresis and a setpoint value of the time interval between the extreme values of the hysteresis, wherein the control device (16) generates a hysteresis of the drive current (I1) by repeatedly switching the first switching element (2) on and off in a first peak hold period after a current value of the drive current (I1) has reached a first current level, and the control device (16) sets extreme values of the hysteresis or sets a time interval between the extreme values of the hysteresis such that the hysteresis of the drive current (I1) falls within a predetermined range from the first current level, characterized by , that the control device (16) calculates a first gradient of the hysteresis of the drive current (I1) using the extreme values of the hysteresis of the drive current (I1) and the time interval between the extreme values and calculates a second gradient of the hysteresis using the setpoint values of the extreme values of the hysteresis and the setpoint value of the time interval between the extreme values of the hysteresis, and the control device (16) sets the extreme values of the hysteresis or the time interval between the extreme values of the hysteresis such that a second difference value between the first gradient and the second gradient falls within the range of the predetermined gradient threshold in a case where the second difference value is not within the range of a predetermined gradient threshold. [2] Solenoid valve drive device (18) according to claim 1, wherein the first switching element (2) is configured to supply the drive current (I1) to the solenoid valve (1) by supplying the solenoid valve (1) with a battery voltage, the control device (16) maintains an open state of the solenoid valve (1) using the battery voltage by switching the first switching element (2) on and off in the first peak holding period after the current value of the drive current (I1) has reached a second current level which is higher than the first current level, and the control device (16) ensures that the time at which the solenoid valve (1) changes from the open state to a closed state is within an allowable time after instructing the first switching element (2) to turn off by causing the hysteresis to fall within a predetermined range from the first current level in the first peak hold period. [3] Solenoid valve drive device (18) according to claim 1, wherein the control device (16) outputs an opening / closing command to a second switching element (3) in order to switch on / off a drive current (I1) supplied to the solenoid valve (1), the second switching element (3) is configured to open the solenoid valve (1) by supplying an increased voltage obtained by increasing a battery voltage to the solenoid valve (1) to supply the drive current (I1) with a second current level higher than the first current level to the solenoid valve (1), and the control device (16) drives and controls the second switching element (3) such that an extreme value of the drive current (I1) falls within a predetermined range from the second current level. [4] Solenoid valve drive device (18) according to claim 3, wherein the control device (16) generates a hysteresis of the drive current (I1) by repeatedly switching the second switching element (3) on and off in a second peak hold period after the current value of the drive current (I1) has reached the second current level, and the control device (16) sets extreme values of the hysteresis or a time interval between the extreme values of the hysteresis such that the hysteresis of the drive current (I1) falls within a predetermined range from the second current level. [5] Solenoid valve drive device (18) according to claim 3, wherein the control device (16) switches off the second switching element (3) and detects a measured value of the extreme value of the drive current (I1) when the current value of the drive current (I1) reaches the second current level, and the control device (16) drives and controls the second switching element (3) according to the measured value of the extreme value of the drive current (I1) such that the extreme value of the drive current (I1) falls within a predetermined range from the second current level when, after the second switching element (3) has been switched off, the solenoid valve (1) is opened by switching the second switching element (3) on again. [6] Solenoid valve drive device (18) according to claim 1, wherein the control device (16) detects the first difference value between the extreme value of the hysteresis and a setpoint value of the extreme value of the hysteresis by detecting a difference between a measured value of the drive current (I1) and a setpoint value of the drive current (I1), and the control device (16) repeats the detection of the first difference value and the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis until the first difference value becomes equal to or less than a predetermined threshold value. [7] Solenoid valve drive device (18) according to claim 1, wherein the control device (16) detects the first difference value between the extreme value of the hysteresis and a setpoint value of the extreme value of the hysteresis by detecting a difference between a measured value of the drive current (I1) and a setpoint value of the drive current (I1), and the control device (16) repeats the detection of the first difference value and the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis while the solenoid valve drive device (18) is activated. [8] Solenoid valve drive device (18) according to claim 1, wherein the control device (16) detects the first difference value between the extreme value of the hysteresis and a setpoint value of the extreme value of the hysteresis by detecting a difference between a measured value of the drive current (I1) and a setpoint value of the drive current (I1), and the control device (16) repeats the detection of the first difference value a predetermined number of times and repeats the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis a predetermined number of times. [9] Solenoid valve drive device (18) according to claim 1, wherein the control device (16) detects a first extreme value in the hysteresis of the drive current (I1), and the control device (16) sets the extreme values of the hysteresis or the time interval between the extreme values of the hysteresis so that a second extreme value in the same hysteresis of the drive current (I1) falls within the predetermined range in a case where the first extreme value does not fall within the predetermined range. [10] The solenoid valve driving device (18) according to claim 1, wherein the control device (16) calculates an average value or an execution value of the extreme values of the hysteresis from a first time point to a second time point, and calculates a difference between the calculated value and the hysteresis target value as the first difference value.

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