Control device for electromagnetic actuator

Abstract

The purpose of the present invention is to accurately detect the operation state of a movable element of an electromagnetic actuator. A control device 10 controls an electromagnetic actuator 200 having a stator 206, a coil 205, and a movable element 204 that operates on the basis of current supplied to the coil 205. The control device 10 comprises: an energization unit 11 that switches energization to the coil 205 and thereby supplies switching current to the coil 205; a switching detection unit 13 for detecting rises and falls in the switching current; a switching state calculation unit 14 for calculating the ratio (T1 / T2) between a rise time T1 and a fall time T2; a switching state change detection unit 15 for detecting change in the calculated ratio; and an operation state detection unit 16 that detects the operation state of the movable element 204 on the basis of detected change in the ratio.

Description

Electromagnetic actuator control device

[0001] The present invention relates to a control device for an electromagnetic actuator.

[0002] Vehicle internal combustion engines are required to have high efficiency, high power output, and low emissions. Direct injection internal combustion engines have long been popular as a means of achieving a balanced solution to these requirements. Important challenges for direct injection internal combustion engines include reducing the noise of the high-pressure fuel pump that pressurizes the fuel, and improving the precision of the injection amount of the injector that injects fuel into the cylinders.

[0003] High-pressure fuel pumps are equipped with an electromagnetic actuator that controls the amount of fuel intake. To reduce the noise level of a high-pressure fuel pump, it is necessary to reduce the impact speed of the valve disc that constitutes the intake valve when it closes. This can be achieved by reducing the drive current required to close the valve. However, reducing the drive current too much will result in the valve failing to close. The minimum drive current, which is the limit of drive current required to ensure successful valve closure, differs for each high-pressure fuel pump due to individual differences in the electromagnetic actuator that controls the opening and closing operation of the valve disc. The minimum drive power required to close the valve depends on the force of the spring that presses down on the valve disc. The stronger the spring force, the more power is required to overcome it and close the valve. On the other hand, the stronger the spring force, the slower the valve closes. Therefore, electromagnetic actuators that take a long time to complete valve closure must have a high minimum drive power setting.

[0004] The injector is equipped with an electromagnetic actuator that controls the amount of fuel injected. Even when driven by the same drive current, the injection amount of each injector varies depending on the individual electromagnetic actuator. Since there is a correlation between the timing at which the valve disc completes closing and the injection amount, by controlling the drive current to align the valve closing timing, it is possible to reduce the variation in the injection amount.

[0005] As in these examples, in order to reduce the noise of a high-pressure fuel pump or to improve the accuracy of the injection amount of an injector, it is necessary to accurately detect the timing at which the valve disc is closed. A technique for detecting the timing at which the valve disc is closed is disclosed in Patent Document 1.

[0006] Patent Document 1 discloses a high-pressure fuel pump including a valve body that opens and closes at its tip end an inlet through which fuel flows into a pressurizing chamber, a movable element that is provided at the base end of the valve body, and a stator that attracts the movable element when a coil is energized, characterized in that the high-pressure fuel pump further includes an electromagnetic actuator that causes a current to flow through the coil that changes within a certain range, has a frequency above a set value, and has a timing at which the current changes within a set range.

[0007] Japanese Patent Application Laid-Open No. 2021-32178

[0008] The drive current of an electromagnetic actuator provided in a high-pressure fuel pump or injector can be broadly divided into a peak current that provides energy to start moving the valve disc and armature that are stationary in the valve-open position, and a holding current that maintains the operating state of the armature to keep the valve disc in the valve-closed position. The holding current is supplied to the coil of the electromagnetic actuator as a switching current whose amplitude changes periodically within a certain range. The timing of valve-closing completion is determined by the operating state of the armature, and it is desirable to control it so that it arrives during the period when the holding current is being supplied, from the perspective of reducing drive power and noise.

[0009] The technology disclosed in Patent Document 1 detects the timing of valve closing completion by detecting a change in the frequency of the holding current. However, the inventors discovered that whether the frequency of the holding current increases or decreases as the valve closes depends on the voltage (power supply voltage) of the battery that supplies the current to the coil. Because the timing at which the frequency of the holding current changes varies depending on the power supply voltage, the technology disclosed in Patent Document 1 has room for improvement in terms of ensuring robustness against power supply voltage. Being able to accurately detect the operating state of the mover independently of the power supply voltage is also an important issue for highly accurate control of electromagnetic actuators other than those of high-pressure fuel pumps or injectors.

[0010] The present invention has been made in view of the above, and has as its object to accurately detect the operating state of a mover of an electromagnetic actuator.

[0011] In order to solve the above problem, the control device for an electromagnetic actuator according to the present invention is a control device that controls an electromagnetic actuator having a stator, a coil fixed to the stator, and a mover that operates based on current supplied to the coil, and is characterized by comprising: a current supply unit that switches current flow to the coil to supply a switching current to the coil; a switching detection unit that detects the rise and fall of the switching current supplied to the coil; a switching state calculation unit that calculates the ratio between the time when the rise is detected and the time when the fall is detected; a switching state change detection unit that detects a change in the calculated ratio; and an operation state detection unit that detects the operation state of the mover based on the change in the detected ratio.

[0012] According to the present invention, the operating state of the mover of the electromagnetic actuator can be accurately detected. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0013] 1 is a diagram illustrating a schematic configuration of a direct injection internal combustion engine. A diagram illustrating the configuration of a high-pressure fuel pump. A time chart illustrating the operation of a high-pressure fuel pump. FIG. 4( a) is a diagram illustrating the displacement of the valve body and the moving element when the valve is successfully closed, and FIG. 4( b) is a diagram illustrating the displacement of the valve body and the moving element when the valve is unsuccessfully closed. A diagram illustrating the relationship between the displacement of the plunger and the fuel pressure in the high-pressure pipe. A diagram illustrating the relationship between the peak current supply amount and the moving element's speed just before the valve is completely closed. A diagram illustrating the relationship between the valve closing completion timing and the noise level. A diagram illustrating the configuration of a control device for an electromagnetic actuator. A diagram illustrating details of the current supplied to the coil. A diagram illustrating specific configurations of the switching detection unit, switching state calculation unit, and switching state change detection unit shown in FIG. 8. A diagram illustrating outputs of the differentiation circuit, positive / negative determination circuit, smoothing circuit, and inflection point extraction circuit shown in FIG. 10. A diagram illustrating specific configurations of the switching detection unit, switching state calculation unit, and switching state change detection unit of a second embodiment. A diagram illustrating outputs of the energization detection circuit, smoothing circuit, and inflection point extraction circuit shown in FIG. 12.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that components or functions denoted by the same reference numerals in each embodiment have the same components or functions in each embodiment unless otherwise specified, and description thereof will be omitted.

[0015] First Embodiment A control device 10 for an electromagnetic actuator 200 according to a first embodiment will be described with reference to FIGS. 1 to 11. FIG.

[0016] FIG. 1 is a diagram illustrating the general configuration of a direct injection internal combustion engine 100. As shown in FIG.

[0017] In a direct injection internal combustion engine 100 (hereinafter also referred to as "internal combustion engine 100"), fuel stored in a fuel tank 101 is pressurized to about 0.4 MPa by a feed pump 102, and is further pressurized to several tens of MPa by a high-pressure fuel pump 103. The pressurized fuel passes through high-pressure piping 104 and is injected from an injector 105 into a cylinder 106 of the internal combustion engine 100.

[0018] The injected fuel is mixed with air drawn into cylinder 106 by the movement of piston 107. This mixture is ignited by a spark generated by spark plug 108, causing an explosion. The heat generated by the explosion causes the mixture in cylinder 106 to expand, pushing piston 107 down. The force pushing piston 107 down is transmitted via link mechanism 109 to rotate crankshaft 110. The rotation of crankshaft 110 is transmitted to the wheels via the transmission, providing the force to move the vehicle.

[0019] While high efficiency, high power output, and low exhaust emissions are primarily required for the internal combustion engine 100, reduced noise and vibration are also required as added value. In the high-pressure fuel pump 103, when the valve element 203 constituting the intake valve opens and closes, noise is generated by collision between the valve element 203 and a stopper 208, or between the movable element (anchor) 204 and a stator 206, or between the valve element 203 and a seat portion 207. Automobile manufacturers and suppliers are competing fiercely to reduce this noise.

[0020] FIG. 2 is a diagram illustrating the configuration of the high-pressure fuel pump 103.

[0021] High-pressure fuel pump 103 includes a plunger 202 that moves up and down with the rotation of a cam 201 attached to a camshaft of internal combustion engine 100, a valve body 203 that constitutes an intake valve that opens and closes in synchronization with the up and down movement of plunger 202, and an electromagnetic actuator 200 that controls the opening and closing movement of valve body 203.

[0022] High-pressure fuel pump 103 has a casing 223, and a pressurization chamber 211 is provided inside casing 223. Fuel flows into pressurization chamber 211 from the low-pressure pipe 111 side through an inlet 225 and a communication port 221. The fuel that flows into pressurization chamber 211 is discharged to the high-pressure pipe 104 side through an outlet 222. Outlet 222 is opened and closed by discharge valve 210. Discharge valve 210 is constantly biased by a spring 226 in a direction that closes outlet 222. When the pressure (fuel pressure) in pressurization chamber 211 overcomes the repulsive force of spring 226, outlet 222 opens and discharges fuel.

[0023] The flow of fuel into the pressurizing chamber 211 is regulated by a valve element 203 that opens and closes an inlet 225. The opening and closing operation of the valve element 203 is controlled by an electromagnetic actuator 200. The electromagnetic actuator 200 is a device that converts electrical energy into mechanical energy via magnetic energy. The electromagnetic actuator 200 has a stator 206 that is a magnetic core, a coil 205 fixed to the stator 206, and a mover 204 that operates based on a current supplied to the coil 205.

[0024] The movable element 204 abuts against the valve element 203 biased by a spring 215 to restrict the movement of the valve element 203, and controls the opening and closing operation of the valve element 203 by moving the valve element 203 in conjunction with the movement of the movable element 204. The movable element 204 is attracted to the stator 206 by a magnetic force generated by a current supplied to the coil 205, and moves the valve element 203. In other words, the movement of the movable element 204 in the axial direction (the left-right direction in FIG. 2 ) is controlled by controlling the current flow through the coil 205.

[0025] The mover 204 is connected to the stator 206 by a spring 209. The mover 204 is constantly biased in the valve opening direction (to the right in FIG. 2 ) by the spring 209. As a result, the mover 204 keeps the valve element 203 in the valve open position when the coil 205 is de-energized. Such a high-pressure fuel pump 103 is called a normally open type high-pressure fuel pump, and although a normally open type will be described in this embodiment, the pump can also be applied to a normally closed type by interchangeably referring to the open and closed valves.

[0026] When the coil 205 is energized, an electromagnetic attractive force is generated between the stator 206 and the armature 204. When this electromagnetic attractive force overcomes the repulsive force of the spring 209, the armature 204, which is provided on the base end side of the valve element 203, is attracted in the valve closing direction (to the left in FIG. 2 ). When the armature 204 is attracted to the stator 206, the valve element 203 functions as a check valve that opens and closes based on the differential pressure between the upstream and downstream sides of the valve element 203 and the repulsive force of the spring 215. Therefore, as the armature 204 is attracted in the valve closing direction by the magnetic force, the valve element 203 is pushed by the spring 215 and moves in the valve closing direction. When the valve element 203 moves in the valve closing direction by a set lift amount, the valve element 203 seats on the seat portion 207, thereby entering a valve closed state. When the valve element 203 is in the valve closed state, fuel in the pressurization chamber 211 cannot flow back toward the low-pressure pipe 111.

[0027] FIG. 3 is a time chart illustrating the operation of the high-pressure fuel pump 103.

[0028] The rotation angle of the cam 201 is detected so that the valve element 203 opens and closes in synchronization with the up and down movement of the plunger 202. After the cam 201 has rotated a predetermined angle (P_ON timing) from the top dead center (TDC), for example, a voltage V begins to be applied to both ends of the coil 205 (timing t1). This voltage V increases the current I flowing through the coil 205 according to equation 1: LdI / dt=V-RI (Equation 1).

[0029] Here, L in Equation 1 is the inductance of the coil 205 and the wiring, and R in Equation 1 is the resistance of the coil 205 and the wiring. As the current I increases, the electromagnetic attraction force Fmag with which the stator 206 attracts the mover 204 also increases.

[0030] When the electromagnetic attractive force Fmag becomes greater than the repulsive force Fsp of the spring 209, the mover 204, which has been pressed down by the repulsive force Fsp, starts to move toward the stator 206 (timing t2). When the mover 204 moves, the valve element 203 is pushed by the spring 215 and moves toward the stator 206 following the mover 204.

[0031] Eventually, the valve element 203 collides with and seats on the seat portion 207. This collision blocks the fuel flow path (dotted line in FIG. 2), preventing the fuel pressurized by the rising of the plunger 202 from returning to the low-pressure pipe 111, and the pressure in the pressurizing chamber 211 rises (timing t4).

[0032] When the pressure in the pressurizing chamber 211 becomes greater than the repulsive force Fsp_out of the spring 226 pressing against the discharge valve 210, the discharge valve 210 opens, and the pressurized fuel is discharged into the high-pressure pipe 104 as the plunger 202 rises. After that, at timing t5, the drive pulse is turned OFF and a reverse voltage is applied to the coil 205, thereby cutting off the holding current that had been supplied to the coil 205.

[0033] When the cam angle passes top dead center and the plunger 202 starts to descend (timing t6), the pressure in the pressurizing chamber 211 decreases, and when this pressure becomes smaller than the repulsive force Fsp_out of the spring 226, the discharge valve 210 closes and the discharge of fuel ends.

[0034] Furthermore, due to the pressure drop in the pressurizing chamber 211, the movable element 204 moves together with the valve element 203 from the valve-closed position to the valve-open position (timing t7 to t8).

[0035] Through this operation, the high-pressure fuel pump 103 sends fuel from the low-pressure pipe 111 to the high-pressure pipe 104. During this process, noise is generated at the timing when the movable element 204 collides with the stator 206 and the valve element 203 collides with the seat portion 207, completing the valve closing process (timing t4 in FIG. 3 ), and at the timing when the valve element 203 collides with the stopper 208, completing the valve opening process (timing t8 in FIG. 3 ). This noise can be unpleasant for vehicle occupants, particularly when the internal combustion engine 100 is idling. Automobile manufacturers and suppliers are competing to reduce this noise. In this embodiment, the aim is to reduce noise at the valve closing process.

[0036] The drive current that drives the electromagnetic actuator 200 is roughly divided into a peak current (the diagonally shaded portion of the current waveform in FIG. 3 ) and a holding current (the horizontally shaded portion of the current waveform in FIG. 3 ). The peak current is a current that provides energy to the armature 204, which is held down by the spring 209 and stationary in the valve open position, to cause the armature 204 to move in order to close the valve. On the other hand, the holding current is a current that attracts the armature 204, which has approached the stator 206, until it collides with the stator 206, thereby maintaining the operating state of the armature 204 in contact with the stator 206 in order to maintain the valve disc 203 in the valve closed position. The timing at which the valve is closed (hereinafter also referred to as "valve closing completion timing Tb") is controlled to occur during the period in which the holding current is supplied. By reducing the amount of peak current supplied, the momentum of the valve closing weakens, the speed of the valve disc 203 and the armature 204 during valve closing is reduced, and noise can be reduced. However, if the peak current supply amount is reduced too much, the valve will fail to close. Therefore, it is important to reduce the peak current supply amount as much as possible while still allowing the valve to close successfully. As shown in Figure 3, the maximum current value of the peak current is Im and the maximum current value of the holding current is Ik.

[0037] Fig. 4(a) is a diagram illustrating the displacement of the valve element 203 and the movable element 204 when the valve is successfully closed. Fig. 4(b) is a diagram illustrating the displacement of the valve element 203 and the movable element 204 when the valve is unsuccessfully closed. Fig. 5 is a diagram illustrating the relationship between the displacement of the plunger 202 and the fuel pressure in the high-pressure pipe 104. Fig. 6 is a diagram illustrating the relationship between the peak current supply amount and the speed of the movable element 204 immediately before the valve is completely closed. Fig. 7 is a diagram illustrating the relationship between the valve-closing completion timing and the noise level.

[0038] The role of the high-pressure fuel pump 103 is to compress fuel in the low-pressure pipe 111 and discharge it into the high-pressure pipe 104 so as to maintain the fuel pressure in the high-pressure pipe 104 at a target value. For this purpose, the high-pressure pipe 104 is provided with a fuel pressure sensor 250 that measures the fuel pressure in the high-pressure pipe 104. The control device 10 (see FIG. 8 ) for the electromagnetic actuator 200 controls the timing at which current supply to the coil 205 (P_ON timing) is started so that the measurement value of the fuel pressure sensor 250 tracks the target value. If the measurement value of the fuel pressure sensor 250 is lower than the target value, the timing at which current supply to the coil 205 is started is advanced in order to increase the discharge amount. If the measurement value of the fuel pressure sensor 250 is higher than the target value, the timing at which current supply to the coil 205 is started is delayed in order to reduce the discharge amount. PID control can generally be applied to this control.

[0039] As described above, reducing the peak current supply amount reduces the speed at which the valve element 203 closes, thereby reducing noise. However, reducing the peak current supply amount too much results in a failure to close the valve. That is, when a peak current supply amount sufficient to close the valve is supplied to the coil 205, the valve element 203 and the moving element 204 behave as shown in FIG. 4( a) (valve closing successful). When a peak current supply amount sufficient to close the valve is not supplied to the coil 205, the valve element 203 and the moving element 204 cannot overcome the repulsive force of the spring 209 and behave as shown in FIG. 4( b) (valve closing failed).

[0040] If the valve is successfully closed, the valve element 203 blocks the inlet 225 leading from the low-pressure pipe 111 to the pressurizing chamber 211, and the fuel pressure increased in the pressurizing chamber 211 due to the rise of the plunger 202 is transmitted to the high-pressure pipe 104. As a result, as shown by the right-upward diagonal line A in Figure 5, the fuel pressure in the high-pressure pipe 104 increases in synchronization with the rise of the plunger 202. On the other hand, if the valve is unsuccessful in closing, even if the plunger 202 rises, the fuel in the pressurizing chamber 211 escapes to the low-pressure pipe 111. As a result, even if the plunger 202 rises, the fuel pressure in the high-pressure pipe 104 does not increase, as shown by the right-downward diagonal line B in Figure 5.

[0041] The control device 10 for the electromagnetic actuator 200 can determine whether the valve is successfully closed or not based on the measurement value of the fuel pressure sensor 250 provided in the high-pressure pipe 104. The control device 10 increases the amount of current supplied to the coil 205 if the valve is not successfully closed, and decreases the amount of current supplied to the coil 205 if the valve is successfully closed. In this way, by determining whether the valve is successfully closed or not based on the fuel pressure fluctuations in the high-pressure pipe 104 synchronized with the up and down movement of the plunger 202 and increasing or decreasing the amount of current supplied, the control device 10 can control the drive current of the electromagnetic actuator 200 to be close to the minimum current supply amount that results in successful valve closing. This allows the control device 10 to reduce noise generated when the electromagnetic actuator 200 closes.

[0042] However, when the drive current of the electromagnetic actuator 200 is controlled near the minimum current supply amount as described using FIG. 5 , valve closing failure occurs with a certain frequency. The inventor investigated the characteristics of the electromagnetic actuator 200 to avoid such valve closing failure. As a result, the inventor found that the relationship between the peak current supply amount (peak current integral value II) and the velocity vel_Tb of the movable element 204 immediately before valve closing completion has a dead zone D, as shown in FIG. 6 , where the velocity vel_Tb immediately before valve closing completion does not decrease even if the peak current supply amount decreases. Note that the peak current supply amount shown in FIG. 6 is the integral value of the drive current from timing t1 when the peak current starts to be supplied to timing t3 when the peak current starts to decrease in FIG. 3 .

[0043] When the maximum current value Im of the peak current is applied for a sufficiently long time, the mover 204 is constantly accelerating. However, as the peak current width is shortened, the mover 204 decelerates from the point at which the maximum current value Im of the peak current is terminated. The mover 204 then coasts toward the stator 206 at a low speed. As the mover 204 approaches the stator 206, it is accelerated again by the electromagnetic attractive force generated by the holding current. When the mover 204 is re-accelerated from a state where its speed is approximately zero by the electromagnetic attractive force of the holding current, it moves at an approximately constant speed regardless of its previous motion. This is the reason why a dead zone D exists in the relationship between the peak current supply amount and the speed vel_Tb of the mover 204 immediately before the valve closing is completed.

[0044] Due to the existence of this dead zone D, the relationship between the level of noise generated in conjunction with valve closing and the valve closing completion timing Tb (the timing at which the movable element 204 collides with the stator 206) includes a saturation region Tr in which the noise level does not decrease even if the valve closing completion timing Tb changes, as shown in Figure 7. This saturation region Tr does not differ significantly even if the power supply voltage of the electromagnetic actuator 200 is different, and is a region that is common to various power supply voltages.

[0045] Even if the peak current supply amount is further reduced below the dead band D, the speed vel_Tb of the movable element 204 immediately before the completion of valve closing cannot be reduced to a value equal to or greater than the speed in the dead band D, and in fact, valve closing will fail. Therefore, if the valve closing completion timing Tb is in the saturation region Tr, it is possible to minimize the noise level associated with valve closing while suppressing valve closing failure.

[0046] For this reason, the control device 10 of the electromagnetic actuator 200 controls the current to maintain the valve closing completion timing Tb in the saturation region Tr, thereby reducing noise associated with valve closing while suppressing valve closing failure. That is, when the valve closing completion timing Tb is earlier than the target timing in the saturation region Tr, the control device 10 reduces the amount of current supplied to the coil 205, and when the valve closing completion timing Tb is later than the target timing in the saturation region Tr, the control device 10 increases the amount of current supplied to the coil 205. In this way, the control device 10 can control the drive current to maintain the valve closing completion timing Tb in the saturation region Tr, thereby reducing noise associated with valve closing while suppressing valve closing failure.

[0047] To achieve control that maintains the valve closing completion timing Tb in the saturation region Tr, it is necessary to accurately detect the valve closing completion timing Tb. Therefore, hereinafter, a control device 10 for an electromagnetic actuator 200 that can accurately detect the valve closing completion timing Tb will be described with reference to Figures 8 to 11.

[0048] Fig. 8 is a diagram illustrating the configuration of the control device 10 for the electromagnetic actuator 200. Fig. 9 is a diagram illustrating details of the current supplied to the coil 205. Fig. 10 is a diagram illustrating specific configurations of the switching detection unit 13, switching state calculation unit 14, and switching state change detection unit 15 shown in Fig. 8. Fig. 11 is a diagram illustrating outputs of the differentiation circuit 17, positive / negative determination circuit 18, smoothing circuit 19, and inflection point extraction circuit 20 shown in Fig. 10.

[0049] Both ends of the coil 205 of the electromagnetic actuator 200 are connected to a drive circuit 300 that supplies a drive current for driving the electromagnetic actuator 200. The drive circuit 300 has a battery 301 that is a supply source of the current, and a switch 302 that switches whether or not the voltage of the battery 301 (power supply voltage) is applied to the coil 205. In other words, the switch 302 switches the power supply to the coil 205 between on and off.

[0050] The control device 10 of the electromagnetic actuator 200 controls the drive current of the electromagnetic actuator 200, i.e., the current supplied to the coil 205, by controlling the switch 302 of the drive circuit 300. Specifically, the control device 10 includes a current supply unit 11, a measurement unit 12, a switching detection unit 13, a switching state calculation unit 14, a switching state change detection unit 15, and an operation state detection unit 16.

[0051] The current supplying unit 11 switches the current supplied to the coil 205 to supply a switching current to the coil 205 so that the current flowing through the coil 205 is maintained within a certain range. As described above, the drive current of the electromagnetic actuator 200 is roughly divided into a peak current and a holding current. The holding current is supplied to the coil 205 as a switching current whose amplitude changes periodically within a certain range, as shown in FIG. 9 , by the current supplying unit 11 switching the current supplied to the coil 205.

[0052] The measuring unit 12 measures the switching current supplied to the coil 205 and outputs the measured value to the current supplying unit 11 and the switching detection unit 13. The current supplying unit 11 controls the timing of turning on and off the current to the coil 205 based on the switching current measured by the measuring unit 12 and preset upper and lower limit values ​​of the switching current.

[0053] The switching detection unit 13 detects the rising and falling edges of the switching current supplied to the coil 205. The rising edge of the switching current refers to an increase in the value of the switching current as shown in section T1 in Fig. 9 when the current supply to the coil 205 is turned on. The falling edge of the switching current refers to a decrease in the value of the switching current as shown in section T2 in Fig. 9 when the current supply to the coil 205 is turned off.

[0054] The switching detection unit 13 of the first embodiment detects an increase in the switching current as a rising edge of the switching current, and detects a decrease in the switching current as a falling edge of the switching current.

[0055] Specifically, as shown in Fig. 10 , the switching detection unit 13 of the first embodiment may be configured with a differentiation circuit 17 that differentiates the switching current output from the measurement unit 12, and a positive / negative determination circuit 18 that determines whether the output of the differentiation circuit 17 is positive or negative. The differentiation circuit 17 may be configured with a known analog circuit having an operational amplifier, a resistor, and a capacitor as circuit components. The positive / negative determination circuit 18 may be configured with a known analog circuit such as a comparator circuit having an operational amplifier and a resistor as circuit components. The outputs of the differentiation circuit 17 and the positive / negative determination circuit 18 are as shown in Fig. 11 .

[0056] The switching state calculation unit 14 calculates the ratio (T1 / T2) between the time when the rising edge of the switching current is detected by the switching detection unit 13 (hereinafter also referred to as the "rising edge time T1") and the time when the falling edge of the switching current is detected (hereinafter also referred to as the "falling edge time T2").

[0057] The switching state calculation unit 14 of the first embodiment detects the time when an increase in the switching current is detected as a rise time T1, and detects the time when a decrease in the switching current is detected as a fall time T2. The switching state calculation unit 14 of the first embodiment calculates the ratio (T1 / T2) between the time when an increase in the switching current is detected and the time when a decrease in the switching current is detected.

[0058] Specifically, the switching state calculation unit 14 of the first embodiment may be configured with a smoothing circuit 19 that smooths the output of the positive / negative determination circuit 18, as shown in Fig. 10. The smoothing circuit 19 may be configured with a known analog circuit such as a filter circuit that includes resistors and capacitors as circuit components. The output of the smoothing circuit 19 is as shown in Fig. 11. The vertical axis of the output of the smoothing circuit 19 shown in Fig. 11 represents the ratio (T1 / T2).

[0059] The switching state change detection unit 15 detects a change in the ratio (T1 / T2) calculated by the switching state calculation unit 14. Specifically, as shown in FIG. 10 , the switching state change detection unit 15 may be configured with an inflection point extraction circuit 20 that extracts an inflection point of the output of the smoothing circuit 19. The inflection point extraction circuit 20 may be configured with a known analog circuit in which two differentiation circuits are connected in series. The inflection point extraction circuit 20 outputs the result of second-order differentiation of the input. The output of the inflection point extraction circuit 20 is as shown in FIG. 11 .

[0060] The operation state detection unit 16 detects the operation state of the mover 204 based on the change in the ratio (T1 / T2) detected by the switching state change detection unit 15. Specifically, the operation state detection unit 16 detects the timing at which the detected change in the ratio (T1 / T2) occurs as the timing at which the mover 204 operates, i.e., the valve-closing completion timing Tb. More specifically, the operation state detection unit 16 of the first embodiment searches for a peak in the second-order derivative of the ratio (T1 / T2) output by the inflection point extraction circuit 20, and detects the timing at which the searched peak occurs as the valve-closing completion timing Tb. The timing at which the searched peak occurs indicates the timing at which the inflection point extracted by the inflection point extraction circuit 20 occurs, and indicates the timing at which a change in the ratio (T1 / T2) occurs.

[0061] Note that the second-order differentiation of an input signal has the property of emphasizing noise in the signal, but a method of second-order differentiation that does not emphasize noise is described in documents such as IFAC-PapersOnLine 51(31):35-40, DOI: 10.1016 / j.ifacol. 2018.10.007, or "Decrease of Minimum Injection Fuel Mass on the Basis of the Micro-sec-level Production Error Detection".

[0062] In order to accurately detect the valve-closing completion timing Tb, the inventors investigated the characteristics of the switching current supplied to the coil 205 using various power supply voltages. As a result, the inventors found that, as shown in FIG. 9 , regardless of the power supply voltage, the ratio (T1 / T2) of the rise time T1 to the fall time T2 of the switching current before the valve-closing completion timing Tb is greater than the ratio (T1 / T2) of the rise time T1 to the fall time T2 of the switching current after the valve-closing completion timing Tb. This is because, before the valve-closing completion timing Tb, the rise of the switching current is delayed due to the back electromotive force generated in the coil 205, and after the valve-closing completion timing Tb, the back electromotive force disappears. This phenomenon occurs regardless of the power supply voltage. This means that the ratio (T1 / T2) of the rise time T1 to the fall time T2 of the switching current changes before and after the valve-closing completion timing Tb. Therefore, by detecting the timing of the change in the ratio (T1 / T2), the control device 10 can accurately detect the valve-closing completion timing Tb without depending on the power supply voltage.

[0063] As described above, the control device 10 of the first embodiment is a device that controls the electromagnetic actuator 200 having the stator 206, the coil 205 fixed to the stator 206, and the mover 204 that operates based on the current supplied to the coil 205. The control device 10 includes an energizer 11 that switches energization to the coil 205 to supply a switching current to the coil 205, a switching detector 13 that detects the rising and falling edges of the switching current supplied to the coil 205, a switching state calculator 14 that calculates the ratio (T1 / T2) between the time (T1) at which the rising edge is detected and the time (T2) at which the falling edge is detected, a switching state change detector 15 that detects a change in the calculated ratio (T1 / T2), and an operation state detector 16 that detects the operation state of the mover 204 based on a change in the detected ratio (T1 / T2).

[0064] As a result, even if the frequency of the switching current changes depending on the power supply voltage, the control device 10 can accurately detect the operating state of the mover 204 without depending on the power supply voltage. Therefore, the control device 10 can accurately detect the operating state of the mover 204 of the electromagnetic actuator 200.

[0065] Furthermore, in the control device 10 of the first embodiment, the switching detection unit 13 detects an increase in the switching current as a rising edge of the switching current, and detects a decrease in the switching current as a falling edge of the switching current. The operation state detection unit 16 detects the timing at which the detected ratio (T1 / T2) changes as the timing at which the mover 204 operates.

[0066] This allows the control device 10 to reliably detect the rise time T1 and fall time T2 of the switching current, and therefore the timing at which a change in the ratio (T1 / T2) occurs. Therefore, the control device 10 can accurately and reliably detect the timing at which the mover 204 operates (valve closing completion timing Tb) without depending on the power supply voltage. Therefore, the control device 10 can accurately and reliably detect the operating state of the mover 204 of the electromagnetic actuator 200.

[0067] Furthermore, in the control device 10 of embodiment 1, the switching detection unit 13 is composed of a differentiation circuit 17 that differentiates the switching current and a positive / negative determination circuit 18 that determines whether the output of the differentiation circuit 17 is positive or negative. The switching state calculation unit 14 is composed of a smoothing circuit 19 that smoothes the output of the positive / negative determination circuit 18. The switching state change detection unit 15 is composed of an inflection point extraction circuit 20 that extracts an inflection point of the output of the smoothing circuit 19. The operation state detection unit 16 detects the timing at which the extracted inflection point occurs as the timing at which the mover 204 is operated.

[0068] As a result, the control device 10 can accurately detect the timing at which the mover 204 operates (valve-closing completion timing Tb) simply by combining existing circuits with simple circuit configurations. Therefore, the control device 10 can accurately and easily detect the timing at which the mover 204 operates (valve-closing completion timing Tb) without depending on the power supply voltage. Therefore, the control device 10 can accurately and easily detect the operating state of the mover 204 of the electromagnetic actuator 200.

[0069] The measurement unit 12 may acquire a measurement value of the switching current by sampling the switching current supplied to the coil 205. Specifically, the measurement unit 12 may sample the switching current at a sampling period shorter than the switching period of the current supply unit 11. The measurement unit 12 may acquire a measurement value of the switching current by AD converting the switching current for each sampling.

[0070] The switching detection unit 13 may compare the measurement value I_(t) of the switching current currently acquired by the measurement unit 12 with the measurement value I_(t-1) acquired previously, determine whether the switching current increases or decreases for each sampling by the measurement unit 12, and output a determination value indicating the result of the increase / decrease determination. For example, if the measurement value I_(t) of the switching current currently acquired is greater than the measurement value I_(t-1) acquired previously, the switching detection unit 13 may determine that the switching current has increased and output a determination value a(t)=1, and otherwise determine that the switching current has decreased and output a determination value a(t)=-1.

[0071] The switching state calculation unit 14 may calculate an average value b(t) by averaging the determination value a(t) output from the switching detection unit 13 over a predetermined time period longer than the switching period of the current supply unit 11, and may calculate the ratio (T1 / T2) based on the calculated average value b(t). The average value b(t) may be, for example, a value obtained by averaging the determination values ​​a(t), a(t-1), ..., a(t-(N-1)) output in each sampling from the current sampling to the (N-1)th sampling prior.

[0072] The switching state change detection unit 15 may detect a change in the ratio (T1 / T2) by second-order differentiating the average value b(t) calculated by the switching state calculation unit 14.

[0073] This allows the control device 10 to accurately and easily detect the timing at which the mover 204 is operated (valve closing completion timing Tb) using software without relying on the power supply voltage, and therefore the control device 10 can accurately and easily detect the operating state of the mover 204 of the electromagnetic actuator 200.

[0074] [Embodiment 2] In embodiment 1, the switching detection unit 13 detects the rise and fall of the current by increasing or decreasing the switching current, but in embodiment 2, the switching detection unit 13 detects the rise and fall of the current from the voltage between the terminals of the coil 205.

[0075] 12 and 13, a control device 10 for an electromagnetic actuator 200 according to the second embodiment will be described. In the control device 10 of the second embodiment, the same configuration and operation as those of the first embodiment will not be described.

[0076] Fig. 12 is a diagram illustrating specific configurations of the switching detection unit 13, the switching state calculation unit 14, and the switching state change detection unit 15 according to the second embodiment. Fig. 13 is a diagram illustrating outputs of the conduction detection circuit 21, the smoothing circuit 19, and the inflection point extraction circuit 20 shown in Fig. 12.

[0077] The switching detection unit 13 of the second embodiment detects the application of a voltage between the terminals of the coil 205 as a rising edge of the switching current, and detects the absence of a voltage between the terminals of the coil 205 as a falling edge of the switching current. As in the first embodiment, the operation state detection unit 16 of the second embodiment detects the timing at which a change occurs in the ratio (T1 / T2) detected by the switching state change detection unit 15 as the timing at which the movable element 204 is operated, i.e., the valve closing completion timing Tb.

[0078] As a result, the control device 10 of embodiment 2 can easily detect the rise time T1 and fall time T2 of the switching current from the operation of the current-carrying unit 11, and can therefore detect the timing at which a change in the ratio (T1 / T2) occurs more easily than in embodiment 1. Therefore, the control device 10 of embodiment 2 can detect the timing at which the mover 204 operates (valve-closing completion timing Tb) more easily than in embodiment 1. Therefore, the control device 10 of embodiment 2 can accurately and easily detect the operating state of the mover 204 of the electromagnetic actuator 200.

[0079] 12, the switching detection unit 13 of the second embodiment may be configured with an energization detection circuit 21 that distinguishes between an on-time when the energizing unit 11 applies a voltage between the terminals of the coil 205 and an off-time when the energizing unit 11 does not apply a voltage between the terminals of the coil 205. The output of the energization detection circuit 21 is as shown in FIG.

[0080] As shown in Fig. 12 , the switching state calculation unit 14 of the second embodiment may be configured with a smoothing circuit 19 that smooths the output of the energization detection circuit 21. As in the first embodiment, the switching state change detection unit 15 of the second embodiment may be configured with an inflection point extraction circuit 20 that extracts an inflection point of the output of the smoothing circuit 19. As in the first embodiment, the outputs of the smoothing circuit 19 and the inflection point extraction circuit 20 of the second embodiment are outputs as shown in Fig. 13 .

[0081] Similar to the first embodiment, the operation state detection unit 16 of the second embodiment detects the timing at which the ratio (T1 / T2) detected by the switching state change detection unit 15 changes as the timing at which the mover 204 moves, i.e., the valve-closing completion timing Tb. Specifically, similar to the first embodiment, the operation state detection unit 16 of the second embodiment detects the timing at which the inflection point extracted by the inflection point extraction circuit 20 occurs as the valve-closing completion timing Tb.

[0082] As a result, the control device 10 of embodiment 2 can accurately detect the timing at which the mover 204 is operated (valve closing completion timing Tb) by simply combining existing circuits with simple circuit configurations, similar to embodiment 1. Therefore, the control device 10 of embodiment 2 can accurately and easily detect the timing at which the mover 204 is operated (valve closing completion timing Tb) without depending on the power supply voltage, similar to embodiment 1. Therefore, the control device 10 can accurately and easily detect the operating state of the mover 204 of the electromagnetic actuator 200, similar to embodiment 1.

[0083] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0084] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely realized by hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be realized by software, in which a processor interprets and executes a program that realizes each function. Information such as the program, tape, and file that realizes each function can be stored in a memory, a recording device such as a hard disk or SSD (solid state drive), or a recording medium such as an IC card, SD card, or DVD.

[0085] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected.

[0086] 10...control device, 11...current supply unit, 12...measurement unit, 13...switching detection unit, 14...switching state calculation unit, 15...switching state change detection unit, 16...operation state detection unit, 17...differential circuit, 18...positive / negative determination circuit, 19...smoothing circuit, 20...inflection point extraction circuit, 21...current supply detection circuit, 200...electromagnetic actuator, 204...mover, 205...coil, 206...stator

Claims

1. A control device for an electromagnetic actuator having a stator, a coil fixed to the stator, and a mover that operates based on current supplied to the coil, comprising: a current supply unit that switches current flow to the coil to supply a switching current to the coil; a switching detection unit that detects the rise and fall of the switching current supplied to the coil; a switching state calculation unit that calculates the ratio between the time when the rise is detected and the time when the fall is detected; a switching state change detection unit that detects changes in the calculated ratio; and an operating state detection unit that detects the operating state of the mover based on the change in the detected ratio.

2. The control device for an electromagnetic actuator as described in claim 1, characterized in that the switching detection unit detects an increase in the switching current as the rising edge and detects a decrease in the switching current as the falling edge, and the operation state detection unit detects the timing at which the detected change in the ratio occurs as the timing at which the movable element operates.

3. The control device for an electromagnetic actuator as described in claim 1, characterized in that the switching detection unit detects the application of voltage between the terminals of the coil as the rising edge and detects the absence of voltage being applied between the terminals of the coil as the falling edge, and the operation state detection unit detects the timing at which the detected change in the ratio occurs as the timing at which the mover is operated.

4. The control device for an electromagnetic actuator as described in claim 2, characterized in that the switching detection unit is composed of a differentiation circuit that differentiates the switching current and a positive / negative judgment circuit that judges whether the output of the differentiation circuit is positive or negative, the switching state calculation unit is composed of a smoothing circuit that smoothes the output of the positive / negative judgment circuit, the switching state change detection unit is composed of an inflection point extraction circuit that extracts an inflection point of the output of the smoothing circuit, and the operation state detection unit detects the timing at which the extracted inflection point occurs as the timing at which the movable element is operated.

5. The control device for an electromagnetic actuator as described in claim 3, characterized in that the switching detection unit is composed of an energization detection circuit that distinguishes between an on time when the energization unit applied a voltage between the terminals of the coil and an off time when the energization unit did not apply the voltage between the terminals of the coil, the switching state calculation unit is composed of a smoothing circuit that smoothes the output of the energization detection circuit, the switching state change detection unit is composed of an inflection point extraction circuit that extracts an inflection point of the output of the smoothing circuit, and the operation state detection unit detects the timing at which the extracted inflection point occurred as the timing at which the movable element was operated.

6. A control device for an electromagnetic actuator as described in claim 2, further comprising a measurement unit that samples the switching current at a sampling period shorter than the switching period of the current-carrying unit to obtain a measurement value of the switching current, wherein the switching detection unit compares the currently obtained measurement value with the previously obtained measurement value to determine whether the switching current has increased or decreased for each sampling by the measurement unit and outputs a determination value indicating the result of the increase / decrease determination, and wherein the switching state calculation unit calculates an average value by averaging the output determination values ​​over a predetermined time longer than the switching period of the current-carrying unit, and calculates the ratio based on the calculated average value.