JP5792227B2 - Solenoid valve drive control device - Google Patents

Description

  The present invention relates to a drive control device for a solenoid valve, and more particularly to a device that controls opening and closing of a solenoid valve that controls the flow rate of a fluid, such as a fuel injection valve and an exhaust gas recirculation control valve mounted on an internal combustion engine.

  Patent Document 1 discloses a method of detecting the actual valve closing timing of a solenoid valve based on the voltage across the solenoid after the drive current supplied to the solenoid of the solenoid valve is cut off. According to this method, the time corresponding to the inflection point in the change characteristic of the both-ends voltage is detected as the actual valve closing timing.

Japanese Utility Model Publication No. 60-164181

  The method of Patent Document 1 estimates the time point corresponding to the inflection point in the voltage change characteristic as the actual valve closing timing, but a specific method for specifying the time point corresponding to the inflection point is shown. Absent.

  The present invention has been made paying attention to this point, and appropriately estimates the time point corresponding to the inflection point in the voltage change characteristic at both ends of the solenoid immediately after the drive current of the solenoid valve is interrupted, An object of the present invention is to provide an electromagnetic valve drive control device capable of accurately detecting the timing.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a drive control device for a solenoid valve (2) for controlling a flow rate of fluid, and a terminal for detecting a terminal voltage (VSL) of a solenoid (39) of the solenoid valve. Voltage detection means, filtering means for extracting a specific frequency component from a detection signal of the terminal voltage (VSL) immediately after stopping energization of the solenoid, and a valve body (32) of the electromagnetic valve based on the specific frequency component ) is provided with an estimation means for estimating a seating timing of the valve seat (37) (tCL), as current command time of the solenoid (Ti) is short, a high setting to Rukoto the extraction frequency of the filtering means Features.

According to this configuration, the terminal voltage of the solenoid of the solenoid valve is detected, and a specific frequency component is extracted and extracted from the terminal voltage detection signal (hereinafter referred to as “valve closing operation voltage signal”) immediately after the energization of the solenoid is stopped. and a valve body of the solenoid valve based on a particular frequency component is estimated seated timing seated on the valve seat, the shorter the current command time of the solenoid, the extraction frequency of the filtering means Ru is set high. When the valve body of the solenoid valve is seated on the valve seat, the rate of change of the acceleration of the valve body is maximized, which is considered to appear as an inflection point of the voltage change characteristic, so a specific frequency component is extracted The timing at which the output signal of the bandpass filter process takes a peak value can be estimated as the timing corresponding to the inflection point. That is, since the rate of change of acceleration is indicated by a parameter corresponding to the second-order differential value of the valve closing operating voltage signal, high-pass filter processing corresponding to second-order differentiation and low-pass filter processing excluding unnecessary high-frequency components are performed. The specific frequency component is extracted by the combined band-pass filter processing, and the timing at which the filtered output signal takes a peak value can be estimated as the inflection point corresponding point, that is, the seating timing of the valve body, and the actual valve closing timing can be accurately Can be detected. In addition, when the energization command time of the solenoid is shortened, the valve closing operation is started before the solenoid valve is stably opened fully, and it has been confirmed that the main frequency component of the valve closing operation voltage signal is increased. Therefore, by setting the extraction frequency of the filtering means higher as the solenoid energization command time is shorter, it is possible to appropriately extract a signal for specifying the time point corresponding to the inflection point, and to estimate the seating timing. Can be increased.

The invention according to claim 2, in the driving control device of an electromagnetic valve according to claim 1, wherein the estimated seated timing (tCL) actual valve time of the solenoid valve based on (TopenA) requested opening It further comprises feedback control means for controlling to converge at time (Topen).

  According to this configuration, the actual valve opening time of the solenoid valve is controlled so as to converge to the required valve opening time based on the estimated seating timing. It is possible to prevent the control accuracy from being lowered and to accurately control the actual valve opening time to the required valve opening time.

According to a third aspect of the present invention, in the electromagnetic valve drive control device according to the first or second aspect , the electromagnetic valve (2) is a core (35) on which an electromagnetic force generated by the solenoid (39) acts. And a valve shaft (31) to which the valve body (32) is fixed has a hammering core structure formed separately.

  According to this configuration, it has been confirmed that the change in the main frequency component of the valve closing operation voltage signal described above is caused by the bounce of the core when the valve body is moved to the maximum lift position. In the electromagnetic valve drive control device having the hammering core structure, a remarkable effect of increasing the estimation accuracy of the actual valve closing timing can be obtained.

1 is a diagram illustrating an internal combustion engine and a control device thereof according to an embodiment of the present invention. It is sectional drawing for demonstrating the structure of the principal part of the fuel injection valve shown in FIG. It is a figure for demonstrating operation | movement of a fuel injection valve. It is a figure for demonstrating the method of estimating the time corresponding to the inflection point (PXO) in the change characteristic of the drive current (ID) of a fuel injection valve. It is a time chart which shows transition of the lift amount (LFTV) of a valve body at the time of the on-off valve operation of a fuel injection valve, and the lift amount (LFTC) of a core. It is a figure which shows the relationship between the valve opening command time (Ti) which is the time from the supply start time (tIS) of drive current to the interruption | blocking time (tIE), and valve closing operation time (Toff). It is a figure for demonstrating the main frequency component in the change characteristic of the solenoid voltage (VSL) at the time of valve closing operation | movement of a fuel injection valve, and the change characteristic. It is a figure which shows the relationship between the actual valve closing timing (tCL) of a fuel injection valve, and the change characteristic of a solenoid voltage (VSL). It is a functional block diagram which shows the structure of a band pass filter. It is a figure which shows the amplitude frequency characteristic of a band pass filter. It is a flowchart of the fuel-injection control process performed with ECU shown in FIG. It is a figure which shows the table referred by the process of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a view showing an internal combustion engine (hereinafter referred to as an “engine”) and a control device thereof according to an embodiment of the present invention. In this embodiment, a fuel injection valve opened by a solenoid valve having a solenoid is opened. The amount of fuel supplied to the engine is controlled by changing the time.

  The four-cylinder engine 1 includes four fuel injection valves 2 corresponding to the cylinders, and the fuel injection valves 2 directly inject fuel into the combustion chamber of the engine 1. Each of the four fuel injection valves 2 is connected to the ECU 5, and its operation is controlled by the ECU 5.

  The fuel injection valve 2 is connected to a delivery pipe 4 through a fuel passage 3, and fuel pressurized by a high-pressure fuel pump (not shown) is supplied to the delivery pipe 4. A fuel pressure sensor 12 for detecting the fuel pressure PF is attached to the delivery pipe 4, and the detection signal is supplied to the ECU 5.

  The ECU 5 includes a voltage / current detection sensor 11 for detecting the voltage VSL across the solenoid of the fuel injection valve 2 and the drive current ID supplied to the solenoid, an engine speed sensor 13 for detecting the engine speed NE, and the engine 1. Various sensors for detecting the engine operating state are connected, such as an intake air flow rate sensor 14 for detecting the intake air flow rate GAIR, an intake air temperature sensor 15 for detecting the intake air temperature TA, and a cooling water temperature sensor 16 for detecting the engine cooling water temperature TW. The detection signals of these sensors are supplied to the ECU 5. The ECU 5 calculates the required valve opening time Topen of the fuel injection valve 2 according to the engine operating state using the detection signals of these sensors, calculates the valve opening command time Ti according to the required valve opening time Topen, and opens the valve. Drive control of the fuel injection valve 2 is performed using the valve command time Ti.

  FIG. 2 is a cross-sectional view for explaining a configuration of a main part of the fuel injection valve 2. The fuel injection valve 2 includes a valve shaft 31, a valve body 32 fixed to the tip of the valve shaft 31, and a valve shaft 31. Flanges 33, 34 fixed to the core, a core 35 on which electromagnetic force acts, a first spring 36 provided between the core 35 and the flange 34, a valve seat 37, a sleeve 38, a solenoid 39, A second spring 40 that urges the flange 34 in the valve closing direction (downward in the figure) and an inner collar 41 having a hollow portion that functions as a fuel passage are provided. The fuel injection valve 2 has a so-called hammering core structure in which a core 35 and a valve shaft 31 to which a valve body 32 is fixed are configured separately.

  FIG. 3 is a diagram for explaining the operation of the fuel injection valve 2. When a drive current is supplied to the solenoid 39 in the closed state shown in FIG. 3A, the core 35 moves upward in the figure. The bottom end of the flange 34 is reached ((b) in the figure). Thereafter, the core 35 moves upward together with the valve shaft 31 and the valve body 32, and when it reaches the lower end of the sleeve 38 ((c) in the figure), a bounce operation that slightly vibrates up and down is performed. The core 35 contacts the sleeve 38 and maintains a stable valve opening state. When the energization of the solenoid 39 is cut off, the core 35 moves downward together with the valve shaft 31 and the valve body 32, and the valve body 32 is seated on the valve seat 37 ((d) in the figure). Thereafter, the core 35 moves away from the lower end of the flange 34 and returns to the original closed state ((e) in the figure).

In the drive control of the fuel injection valve 2, the actual valve opening time TopenA of the fuel injection valve is calculated, and feedback control is performed so that the actual valve opening time TopenA converges to the required valve opening time Topen. In this embodiment, the actual valve opening time TopenA is calculated using the following formula (1). In the equation (1), Ton is the valve opening delay time from the start point tIS of the solenoid 39 to the operation start timing (actual valve opening timing) tOP at which the valve element 32 is separated from the valve seat 37, and Toff is the end of energization of the solenoid 39. This is the valve closing operation time from the time point tIE to the valve closing time point tCL at which the valve body 32 is seated on the valve seat 37. In the present embodiment, the valve opening delay time Ton is calculated based on the change characteristics of the drive current ID supplied to the solenoid 39, and the valve closing operation time Toff is the voltage across the solenoid 39 (hereinafter referred to as "solenoid") as will be described later. It is calculated based on the change characteristic of VSL (referred to as “voltage”).
TopenA = Ti-Ton + Toff (1)

  The operation start time tOP is detected as a time corresponding to the inflection point PXO in the change characteristic of the drive current ID. When the fuel injection valve 2 is opened, the drive current ID changes as schematically shown in FIG. 4, and the rate of increase increases after the inflection point PXO. Estimate tOP. That is, the change amount DID per sampling period DTS of the drive current ID is compared with the determination threshold value DIDTH, and the sampling time one cycle before the sampling time when the change amount DID is equal to or greater than the determination threshold value DIDTH is determined as the operation start time tOP. Estimated.

  FIG. 5 is a time chart showing changes in the lift amount LFTV (solid line) of the valve element 32 and the lift amount LFTC (broken line) of the core 35 when the on-off valve of the fuel injection valve 2 is operated. Corresponding to the case where the drive current ID (energization of the solenoid 39) is cut off at time tIE1 before the lift amount LFTV of the valve body 32 reaches the maximum lift amount, FIG. 5B shows the lift amount LFTV of the valve body 32. This corresponds to the case where the drive current ID is cut off at time tIE2 immediately after reaching the maximum lift amount, and FIG. 5C corresponds to the case where the drive current ID is cut off at time tIE3 after shifting to a stable valve opening state. . Times tCL1, tCL2, and tCL3 shown in these figures correspond to the actual valve closing timing (seat timing of the valve body 32), and the period from time tIEi to tCLi is the valve closing time from the drive current cutoff time to the actual valve closing time. This corresponds to the operating time Toffi (i = 1 to 3).

  FIG. 6 is a diagram showing the relationship between the valve opening command time Ti, which is the time from the supply current supply start time to the shut-off time, and the valve closing operation time Toff. The operating time Toff varies greatly. This is due to the bounce operation that occurs when the core 35 reaches the sleeve 38. In the example shown in FIG. 6, if the valve opening command time Ti exceeds 1.0 msec, the bounce operation is not affected. It becomes almost constant (about 0.4 msec).

  FIG. 7A is a time chart showing the transition of the solenoid voltage VSL when the fuel injection valve 2 is closed, and a large counter electromotive voltage (negative voltage) is generated by cutting off the drive current ID. Thereafter, the characteristics (solid line L1 and broken line L2) that increase toward “0” are shown. The solid line L1 shows the change characteristic of the solenoid voltage VSL during the actual valve closing operation, and the broken line L2 shows the change characteristic of the solenoid voltage VSLFIX in a state where the core 35 is forcibly fixed at the maximum lift position contacting the sleeve 38. Show. A solid line L3 indicates a voltage difference DV (= VSLFIX−VSL) between the solid lines L1 and L2.

  The difference DV is generated when the core 35 (and the valve shaft 31 and the valve body 32) moves in the direction of the valve seat 37. The main frequency component of the difference DV depends on the valve opening command time Ti. Have been confirmed to change. As shown in FIG. 5, this is considered to be caused by the fact that the change characteristics of the lift amounts LFTV and LFTC during the valve closing operation differ depending on the valve opening command time Ti.

  FIG. 7B is a time chart showing the change characteristics of the difference DV in an enlarged manner. The solid line L11 and the broken line L12 correspond to the case where the valve opening command time Ti is 0.5 msec and 1 msec, respectively. To do. FIG. 7B shows a change characteristic after the Hanning window process is performed to perform frequency component analysis on actual detection data. As a result of the frequency component analysis of the change characteristic indicated by the solid line L11 and the broken line L12, the frequency fVSL1 of the main frequency component included in the change characteristic indicated by the solid line L11 is 2350 Hz, and the main frequency included in the change characteristic indicated by the broken line L12 It has been confirmed that the frequency fVSL2 of the component is 1750 Hz, that is, the frequency fVSL of the main frequency component is higher when the valve opening command time Ti is shorter.

  FIG. 8 is a diagram showing the relationship between the actual valve closing timing tCL of the fuel injection valve 2 and the change characteristic of the solenoid voltage VSL. FIG. 8A shows the lift amounts LFTV (solid line L21) and LFTC (broken line L22). FIG. 8B shows the solenoid voltage VSL (solid line L31) and its second-order differential signal DDVSL (broken line L32). From this figure, it can be confirmed that the actual valve closing timing tCL coincides with the timing at which the second-order differential signal DDVSL of the solenoid voltage VSL takes a peak value. This is because the rate of change of the acceleration of the core 35 becomes the maximum at the time when the core 35 moves away from the flange 34 during the valve closing operation of the fuel injection valve 2 (corresponding to the seating timing of the valve body 32), and becomes the inflection point PXC. It is thought to appear.

  Therefore, in the present embodiment, a band obtained by combining a high-pass filter process corresponding to a second-order differential operation and a low-pass filter process excluding unnecessary high-frequency components for a solenoid voltage change signal (valve closing operation voltage signal) during valve closing operation. Bass filter processing is performed, and the timing at which the filtered output signal takes a peak value is estimated as the inflection point PXC in the change characteristic of the solenoid voltage VSL, that is, the actual valve closing timing tCL at which the valve body 32 is seated on the valve seat 37. The time from the cutoff time tIE of the drive current ID to the actual closing timing tCL is calculated as the valve closing operation time Toff.

  In this embodiment, the characteristic parameters x, a, and b (described later) of the bandpass filter processing are set so that the timing at which the filter processing output signal takes the peak value coincides with the seating timing tCL. Further, the characteristic parameters x, a, and b are set to different values according to the valve opening command time Ti, and the pass frequency band is set so as to correspond to the main frequency component frequency fVSL described above.

  FIG. 9 is a functional block diagram showing the configuration of a band-pass filter that executes band-pass filter processing. This band-pass filter includes a moving average unit 51, first and second delay units 52 and 54, and a subtracting unit. 53, 55. The bandpass filter processing by the functional block shown in FIG. 9 is actually executed by calculation by the CPU of the ECU 5.

The moving average unit 51 applies the detected solenoid voltage VSL (k) to the following equation (2) to perform a moving average calculation, and calculates an averaged voltage VAV (k). In Equation (2), k is a discretization time discretized at a sampling period DTS (10 μsec in this embodiment), x is the number of data to be moving averaged, and i is an index parameter.

The first delay unit 52 and the subtraction unit 53 perform an operation represented by the following formula (3) to calculate an intermediate filter output VFINT (k). “A” in Expression (3) is a first discretization delay time corresponding to the delay time in the first delay unit 52.
VFINT (k) = VAV (k) −VAV (ka) (3)

The second delay unit 54 and the subtraction unit 55 perform a calculation represented by the following equation (4) to calculate a filter output VFOUT (k). In Expression (4), b is a second discretization delay time corresponding to the delay time in the second delay unit 54.
VFOUT (k) = VFINT (k) −VFINT (kb) (4)

  The amplitude frequency characteristic of the bandpass filter changes depending on the setting of the characteristic parameters x, a, and b. FIG. 10 shows characteristics (vertical axis is relative output GF) applied in the present embodiment, and FIG. 10 (a) shows first passband characteristics applied when the valve opening command time Ti is relatively short. (X = 9, a = 8, b = 6), and FIG. 10B shows the second passband characteristics (x = 14, a = 18, applied when the valve opening command time Ti is relatively long. b = 15). In the first pass band characteristic, a pass band centered around 2600 Hz is obtained as the lowest pass band, and in the second pass band characteristic, a pass band centered around 1700 Hz is obtained as the lowest pass band.

  FIG. 11 is a flowchart of a fuel injection control process executed by the ECU 5. It should be noted that all the calculations related to the calculation of the valve opening command time Ti described below are performed for each cylinder to be controlled.

  In step S11, the required valve opening time Topen is calculated according to the engine operating state. In step S12, the Ti table shown in FIG. 12 is searched according to the calculated required valve opening time Topen, and the valve opening command time Ti is calculated. To do. In the Ti table shown in FIG. 12, the valve opening command time Ti is set in advance so that the actual valve opening time TopenA coincides with the required valve opening time Topen. Further, according to the actual valve opening time TopenA detected as described later. Learning is corrected. The table setting values shown in FIG. 12 fluctuate in a range where the required valve opening time Topen is small, which is due to the influence of the bounce of the core 35 described above.

  In step S13, it is determined whether or not the valve opening command time Ti is smaller than a predetermined threshold value TiTH (for example, 0.75 msec). If the answer to step S13 is affirmative (YES), the process proceeds to step S14 to execute fuel injection. The valve opening delay time Ton and the valve closing operation time Toff are detected (steps S15 and S16).

  The valve opening delay time Ton is detected by the above-described method (see FIG. 4), and the valve closing operation time Toff is detected by applying the first passband characteristic shown in FIG. The timing at which the filter output VFOUT takes a peak value is estimated as the seating timing tCL.

  On the other hand, when the answer to step S13 is negative (NO) and the valve opening command time Ti is equal to or longer than the predetermined threshold value TiTH, the valve opening delay time Ton and the valve closing operation time Toff are detected in steps S17 to S19. The detection of the valve opening delay time Ton in step S18 is the same as that in step S15, and the detection of the valve closing operation time Toff in step S19 is performed by applying a second passband characteristic shown in FIG. The process is executed, and the timing at which the filter output VFOUT takes the peak value is estimated as the seating timing tCL.

In step S20, the actual valve opening time TopenA is calculated by the above formula (1). In step S21, the valve opening time deviation DTopen is calculated by subtracting the actual valve opening time TopenA from the required valve opening time Topen. In step S22, the valve opening command time Ti is corrected by applying the valve opening time deviation DTopen to the following equation (5). GP in Equation (5) is a control gain.
Ti = Ti + GP × DTOpen (5)

In step S23, the corrected valve opening command time Ti is applied to the following equation (6) to update (learn) the Ti table. Ti on the right side is the valve opening command time corrected in step S22, TiP is a table setting value before update, and CL is an annealing coefficient set to about 0.1, for example.
Ti = CL * Ti + (1-CL) * TiP (6)

  As described above, in this embodiment, the solenoid voltage VSL of the fuel injection valve 2 is detected, and the band-pass filter processing is performed on the solenoid voltage VSL (valve closing operation voltage signal) at the time of closing the valve immediately after the energization of the solenoid 39 is stopped. By doing so, the filter output VFOUT corresponding to the specific frequency component is calculated, and the timing at which the filter output VFOUT takes the peak value is estimated as the seating timing of the valve body 32. When the valve body 32 of the fuel injection valve 2 is seated on the valve seat 37, the rate of change of the acceleration of the core 35 (and the valve body 32) is maximized, which appears as an inflection point of the voltage change characteristic. Therefore, the timing at which the output signal of the bandpass filter process for extracting the specific frequency component takes the peak value can be estimated as the timing corresponding to the inflection point. That is, since the rate of change of acceleration is indicated by a parameter corresponding to the second-order differential value of the valve closing operating voltage signal, high-pass filter processing corresponding to second-order differentiation and low-pass filter processing excluding unnecessary high-frequency components are performed. The specific frequency component is extracted by the combined band-pass filter processing, and the timing at which the filter output VFOUT takes the peak value can be estimated as the inflection point corresponding point, that is, the seating timing tCL of the valve body 32, and the actual valve closing timing can be calculated. It can be detected accurately.

  Further, when the valve opening command time Ti is smaller than the predetermined threshold value TiTH, the first pass band characteristic higher than the pass frequency band of the band pass filter process is selected. When the valve opening command time Ti is shortened, it is confirmed that the main frequency component of the valve closing operation voltage signal is increased because the valve closing operation is started before the fuel injection valve 2 is stably opened fully ( (Refer FIG.7 (b)). Therefore, as the valve opening command time Ti is shorter, the filter output VFOUT for specifying the time point corresponding to the inflection point PXC can be appropriately extracted by setting the passband frequency of the bandpass filter process higher. The estimation accuracy of the seating timing tCL can be improved.

  Further, feedback control is performed so that the actual valve opening time TopenA of the fuel injection valve 2 converges to the required valve opening time Topen based on the estimated seating timing tCL. It is possible to prevent the control accuracy of the valve time TopenA from being lowered, and to accurately control the actual valve opening time TopenA to the required valve opening time Topen.

  It has been confirmed that the change in the main frequency component of the valve closing operation voltage signal described above is caused by the bounce of the core 35 when the valve element 32 is moved to the maximum lift position. In the actual opening time control of the fuel injection valve 2 having the structure, a remarkable effect of increasing the estimation accuracy of the actual closing timing tCL can be obtained.

  In this embodiment, the voltage / current detection sensor 11 constitutes a terminal voltage detection means, and the ECU 5 constitutes a filtering means, an estimation means, and a feedback control means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the example in which the present invention is applied to the fuel injection valve of the internal combustion engine has been described. However, the present invention can also be applied to a general electromagnetic valve for controlling the flow rate of fluid.

2 Fuel injection valve (solenoid valve)
5 Electronic control unit (filtering means, estimation means, feedback control means)
11 Voltage current sensor (terminal voltage detection means)
32 Valve body 37 Valve seat 39 Solenoid

Claims (3)

In a drive control device for a solenoid valve that controls the flow rate of fluid,
Terminal voltage detecting means for detecting a terminal voltage of a solenoid of the solenoid valve;
Filtering means for extracting a specific frequency component from the detection signal of the terminal voltage immediately after stopping energization of the solenoid;
Estimating means for estimating a seating timing at which the valve body of the solenoid valve is seated on a valve seat based on the specific frequency component ;
The shorter energization command time of the solenoid, the drive control device of the solenoid valve, characterized that you set a high extraction frequency of said filtering means. The electromagnetic valve drive according to claim 1, further comprising feedback control means for controlling the actual valve opening time of the electromagnetic valve to converge to the required valve opening time based on the estimated seating timing. Control device. The solenoid valve according to claim 1 or 2, characterized in that it has a core electromagnetic force acts generated by the solenoid, the valve body and a fixed valve stem hammer ring core structure that is configured separately The drive control apparatus of the solenoid valve described in 1.

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