JP4111848B2 - Fuel injection control method and control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronically controlled fuel injection control method for supplying fuel to an engine or the like and a control apparatus therefor, and more particularly, due to fluctuations in power supply voltage and coil resistance of a fuel injection solenoid caused by temperature changes. The present invention relates to a fuel injection control method and a control apparatus for accurately injecting a requested fuel injection amount without any influence.
[0002]
[Prior art]
[Patent Document 1]
JP 58-28537 A
[Patent Document 2]
JP-A-8-4575
[0003]
Proper and appropriate supply of the required fuel injection amount that changes every moment to an internal combustion engine such as an automobile engine including a two-wheeled vehicle is an extremely important factor that affects the performance of the internal combustion engine. For this reason, Patent Document 1 discloses an electronically controlled fuel injection method for an internal combustion engine in which the fuel injection time at the start of the engine is corrected according to the intake air temperature of the engine and the battery voltage.
[0004]
FIG. 18 illustrates a specific example of the control circuit of such a conventional fuel injection device. Here, the fuel injection time is adjusted according to the value of the power supply voltage in view of the fact that the fuel injection amount per unit time injected from the fuel injection device changes due to the fluctuation of the power supply voltage (battery voltage). Yes. That is, the power supply voltage V applied to the power supply terminal 11 _B Is input to a microcomputer 13 of an ECU (Electronic Control Unit) through a power supply voltage input circuit 12. The microcomputer 13 is connected to the power supply voltage V _B Is low, a drive pulse with a longer ON time of the FET 14 is output to the FET drive circuit 15 to adjust the drive time (fuel injection time) of the solenoid 16 longer. Conversely, the power supply voltage V _B Is high, the drive pulse in which the ON time of the FET 14 is adjusted to be shorter is output to the FET drive circuit 15 to adjust the drive time of the solenoid 16 to be shorter. As a result, the fuel injection amount is controlled so as to supply the required appropriate amount of fuel without being affected by fluctuations in the power supply voltage.
[0005]
On the other hand, Patent Document 2 detects the fuel temperature corresponding to the temperature of the electromagnetic coil, sets a correction pulse width for correcting the operation delay time of the fuel injection valve based on the fuel temperature and the battery voltage, and A drive control device for an engine fuel injection valve is disclosed in which a value obtained by adding the correction pulse width to an effective injection pulse width corresponding to the amount of fuel to be supplied is used as a final injection pulse width.
[0006]
[Problems to be solved by the invention]
However, in the control method of correcting the fuel injection time based on the power supply voltage value as shown in FIG. 18, for example, when the temperature of the coil constituting the solenoid 16 rises, the coil resistance value changes, and the power supply Voltage V _B However, it is difficult to properly supply the required fuel injection amount because the coil current changes. This is because the fuel injection amount per unit time of the solenoid 16 varies depending on the coil current value. For this reason, it is conceivable to drive the solenoid 16 at a constant current. However, the operating characteristics including the operation start time of the solenoid 16 greatly vary depending on the temperature, and the cost increases due to the complexity of the control circuit and software processing therefor. There was a problem of inviting.
[0007]
On the other hand, in the drive control apparatus for an engine fuel injection valve disclosed in Patent Document 2, the temperature of the electromagnetic coil whose fuel injection characteristics change depending on the temperature does not necessarily match the fuel temperature, and also detects the fuel temperature. Therefore, it is necessary to dispose the drive control device for the fuel injection valve for the engine in the fuel tank having a limited capacity. Therefore, there is a problem that the fuel storage capacity of the fuel tank is reduced correspondingly.
[0008]
By the way, unlike the conventional type fuel injection system that injects fuel that has been pressurized and sent by a fuel pump or regulator, the inventors of the present invention are electromagnetic fuel injection that pressurizes and injects fuel by itself. A fuel injection system using a pump (hereinafter referred to as "electromagnetic fuel injection system") is being developed.
[0009]
Although this electromagnetic fuel injection system has a great advantage in that it can be reduced in size and cost as compared with the conventional type fuel injection system, the injection amount of the coil current for driving the fuel injection solenoid is reduced. Due to the characteristics that are affected, there is a problem that it is not possible to correct the fuel injection amount corresponding to the required amount only by correcting the increase / decrease of the drive pulse width based on the power supply voltage of the battery. It was.
[0010]
The present invention is to solve the various problems of the conventional fuel injection control device and the control method described above, and corresponds to the fuel injection amount that changes every moment from the engine side. An object of the present invention is to provide a fuel injection control method capable of adjusting the fuel injection amount according to the state of the solenoid for use, and a control device therefor.
[0011]
[Means for Solving the Problems]
The present invention has been made in view of the above problems, A method for controlling an electromagnetic fuel injection pump that pressurizes and injects fuel, and drives the fuel injection pump Immediately before the solenoid stops driving In Coil current Peak value of Measure the peak value The fuel injection control method is characterized in that the drive stop timing of the solenoid is corrected and adjusted based on the above. As a result, the injection amount is affected by the coil current that drives the fuel injection solenoid. Electromagnetic Even a fuel injection device enables an appropriate amount of fuel injection. The It is.
[0012]
A fuel injection control method according to the present invention includes: A method of controlling an electromagnetic fuel injection pump that pressurizes and injects fuel, Said Drive the fuel injection pump The stroke of driving the solenoid for a predetermined time and the peak of the coil current value flowing through the solenoid just before the solenoid stops driving value The process of measuring and the peak value And a step of obtaining a correction value for correcting the drive stop timing of the solenoid, and a step of adjusting the drive stop timing of the solenoid using the correction value.
[0013]
Here, the correction is determined in advance based on the peak current value and the required fuel injection amount for the solenoid, or for various combinations of the peak current value and the required fuel injection amount for the solenoid. A correction value selected according to the combination is used.
[0014]
Further, in the present invention, the correction of the drive stop timing of the solenoid is determined according to one or both of the peak current value and the required fuel injection amount for the solenoid, and the increase of the required fuel injection amount and the driving of the solenoid. A step of obtaining a slope correction value represented by a ratio to the increase in the output pulse width, a step of obtaining a corrected invalid time from the start of driving of the solenoid determined according to the peak current value to the start of fuel injection, And a step of obtaining a correction value obtained by adding the corrected invalid time to a value obtained by multiplying the required fuel injection amount by the inclination correction value, and adjusting the stop timing of the solenoid using the correction value To do. As a result, a more appropriate and appropriate amount of fuel injection can be controlled.
[0015]
Further, in the present invention, at the time of starting the engine or at the first drive when resuming the fuel injection once interrupted, the power supply voltage applied to the solenoid is measured, and the power supply voltage value is determined based on the power supply voltage value. The solenoid drive stop timing is corrected. Then, in the next or subsequent solenoid drive cycle, a correction value for correcting the drive stop timing of the solenoid is obtained and adjusted based on the peak value of the coil current measured this time.
[0016]
The present invention further provides: A control device for a fuel injection device using an electromagnetic fuel injection pump that pressurizes and injects fuel, and for the electromagnetic fuel injection pump solenoid Driving means When, Said Immediately before the solenoid stops driving In Coil current Peak value of Measuring means for measuring the peak value The correction value for correcting the drive stop timing of the solenoid is obtained based on the correction value, and the correction value is used. By the solenoid driving means Stop driving the solenoid of And a fuel injection control device characterized by comprising a control means for adjusting timing.
[0017]
Here, a feedback circuit for returning energy released from the solenoid to the power source when the solenoid is stopped may be provided. The feedback circuit includes a capacitor that charges energy released from the solenoid when the solenoid is stopped. Thereby, the battery power consumption is reduced, and the battery capacity can be reduced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of embodiments of the present invention will be described in detail with reference to the drawings. (1) First embodiment of the present invention
FIG. 1 shows an example of an overall schematic configuration of a fuel injection system including a fuel injection control device according to the present invention.
[0019]
As shown in FIG. 1, the electromagnetic fuel injection system includes a plunger pump 32 that is an electromagnetically driven pump that pumps fuel in a fuel tank 31, and fuel that has been pressurized and fed to a predetermined pressure by the plunger pump 32. An inlet orifice nozzle 33 having an orifice portion to be passed, an injection nozzle 34 for injecting fuel into the intake passage (of the engine) when the fuel passing through the inlet orifice nozzle 33 has a pressure equal to or higher than a predetermined pressure, engine operation information, and plunger A control unit (ECU) 36 configured to output a control signal to the plunger pump 32 and the like based on a coil current (peak value) flowing through a solenoid of the pump 32 (fuel injection solenoid in the present application) is provided as its basic configuration. ing. Here, the control means in the fuel injection control device according to the present invention corresponds to the control unit 36.
[0020]
FIG. 2 illustrates the configuration of the fuel injection control apparatus according to the first embodiment of the present invention. In FIG. 2, a fuel injection solenoid (hereinafter, appropriately referred to as “solenoid” or “coil”) 46 constitutes a plunger pump 32. The plunger pump 32 is driven by a driving means including an N-channel FET 44, FET 48, and FET driving circuit 45, which are switching elements for driving the fuel injection solenoid 46, for example.
[0021]
By the way, although it is not an essential component of the fuel injection device according to the present invention, it is preferable to provide a capacitor 50 and a diode 42 for charging energy released from the solenoid 46 when driving of the solenoid 46 is stopped. Thereby, while reducing the power consumption of the battery 41, the capacity | capacitance reduction of the battery 41 is realizable. This is because the energy stored in the solenoid 46 is reused as driving energy for the solenoid 46 again. In addition, since the capacitor 50 is charged with a voltage higher than the power supply voltage (for example, 12V), the coil current rises rapidly when the solenoid 46 starts to be driven, and the operation start time (invalidity) of the plunger pump 32 becomes invalid. The effect that (time) is shortened can also be acquired.
[0022]
As shown in FIG. 2, the present control device, in addition to this, measures the coil current peak value of the solenoid 46 or the current value immediately before the stop of driving (in this application, this is appropriately referred to as “peak current value”). The detection circuit 6 obtains a correction value for correcting the drive stop timing of the solenoid 46 based on the measured peak current value, and a drive driver and microcomputer 43 for adjusting the stop timing in the next drive of the solenoid 46 based on this correction value. The control means which consists of the control unit (control means) 36 containing etc. is provided.
[0023]
The power supply voltage (V) of the battery 41 is connected to one end of the solenoid 46 via a diode 57. _B ) Is applied. The other end of the solenoid 46 is connected to the drain of the FET 44. As described above, the capacitor 50 for charging the energy released from the solenoid 46 may be connected via the diode 42.
[0024]
A drive output pulse based on an operation signal output from the microcomputer 43 is supplied to the gate of the FET 44 via an FET drive circuit (driver circuit) 45. The on / off operation of the FET 48 may be the same as that of the FET 44, but may be turned on before the solenoid 46 is driven (the FET 44 is turned on). The FET 48 is turned off before the FET 44 is turned off.
[0025]
The source terminal of the FET 44 is grounded via a current detection resistor 52. When the FET 44 is turned on by the drive output pulse, the power supply voltage is supplied from the battery 41 to the solenoid 46, and the drive of the solenoid 46 is started. The current flowing through the solenoid 46 is measured by the current detection circuit 6.
[0026]
In the current detection circuit 6, a voltage drop (“R” generated between both terminals of the current detection resistor 52 (low resistance). ₅₂ "×" coil current value ") is amplified by an amplifier circuit including a series resistor 7, a feedback resistor 8, and an operational amplifier 9, and is output to an analog input terminal of the microcomputer 43. The microcomputer 43 converts the input analog current value into a digital value and stores it in an internal memory. The memory for storing the coil current value stores the peak value Ip of the coil current so as to be rewritten to a new current value when a current value exceeding the currently stored coil current value is input. Yes. Normally, the current flowing through the solenoid 46 increases with time. However, the current immediately before the solenoid 46 is cut off is not necessarily the peak current due to a steep fluctuation (voltage drop) in the short period of the power supply voltage. Not necessarily. In the present invention, by correcting the drive stop timing of the solenoid 46 based on the peak value of the coil current, it is possible to appropriately cope with the required fuel injection amount.
[0027]
In FIG. 2, the energy released from the solenoid 46 when the drive of the solenoid 46 is stopped is charged into the capacitor 50 and reused. However, as shown in FIG. You may make it consume with such a snubber circuit. Alternatively, the other end of the solenoid 46 may be connected to the battery 41 via the diode 42 to charge the battery 41.
[0028]
FIG. 3 shows a schematic flow of the correction processing method using the peak current in the first embodiment. In this embodiment, the peak current when the current of the solenoid 46 reaches the peak is measured, and the demand of the solenoid 46 corresponding to the requested fuel injection amount Qc based on the requested fuel injection amount Qc and the measured peak current value. The drive pulse Pw is adjusted. More specifically, as shown in FIG. 3, the peak value Ip of the coil current flowing through the solenoid 46 is measured, and the required drive pulse Pw of the solenoid corresponding to the required fuel injection amount Qc is calculated based on the measured value. A correction value Pr for increasing or decreasing is obtained, and a drive output pulse Pout having an actual drive pulse width Tout in which the drive time (for example, drive stop timing) of the fuel injection solenoid is adjusted is generated using the correction value Pr. Thus, the solenoid driving time is controlled.
[0029]
The correction value Pr is calculated based on the required fuel injection amount Qc and the peak current value Ip of the coil current flowing through the solenoid 46. When the required drive pulse width is supplied (from the engine side), This required drive pulse width is corrected based on the coil current peak value Ip. This required drive pulse width means the drive time width of the solenoid 46 corresponding to the required fuel injection amount Qc.
[0030]
FIG. 4 shows an example of a correction processing timing chart based on the coil current peak value Ip according to the present invention. FIG. 4 shows the coil current waveform 62 of the solenoid 46 when the driving of the solenoid 46 is started and stopped, the timing 64 for sampling the peak current Ip, and the timing of the correction process 63.
[0031]
As shown in FIG. 4, the coil current starts to flow due to the start of driving of the solenoid 46, increases with time, and becomes zero in a short time after the driving of the solenoid 46 is stopped. Since the coil current peak value Ip during the driving period of the solenoid 46 is held in the memory, the coil current peak value Ip is determined by stopping the driving of the solenoid 46, and the solenoid 46 is determined based on the coil current peak value Ip. Therefore, a correction value for correcting the drive stop timing after the next time is obtained.
[0032]
FIG. 5 shows the required drive pulse Pw corresponding to the required fuel injection amount Qc, the pulse width Tw of the required drive pulse Pw, the coil current I of the solenoid 46, the timing 64 of reading the peak current stored in the memory, and the read The correlation between the calculation of the correction value Pr based on the peak current value Ip and the drive output pulse to the FET 44 that drives the solenoid 46 that is actually output is shown. Symbol Tr is a drive time from the start of driving of the solenoid 46 to the stop thereof. Symbol Tout indicates the pulse width of the drive output pulse Pout. In this case, the actual drive time of the solenoid 46 is adjusted such as to increase or decrease with respect to the requested drive pulse Pw based on the correction value Pr obtained during the previous (or earlier) solenoid drive.
[0033]
In FIG. 5, the coil current continues to increase during the drive period of the solenoid 46 and reaches a peak value immediately before the drive is stopped. For example, the battery power supply voltage at the start of the operation of an air conditioner, a lamp, etc. The coil current may not necessarily show a peak value immediately before the drive is stopped due to a sudden fluctuation (decrease). For this reason, in this embodiment, the peak value of the coil current is sequentially stored in the memory in the microcomputer 43 (FIG. 2), and the fuel injection control is performed by obtaining the correction value based on the stored peak value. We are trying to stabilize and optimize.
[0034]
As shown in FIG. 5, in this fuel injection control method, the drive output pulse rises in synchronization with the rising edge of the required drive pulse Pw, whereby the solenoid 46 is driven and the coil current I begins to flow. Then, the coil current peak value Ip during the drive period of the solenoid 46 is read from the memory after the solenoid 46 is stopped. Based on the coil current peak value Ip and the required fuel injection amount Qc, the required fuel injection amount Qc is determined. A correction value Pr is obtained. The required drive pulse width Tw corresponding to the required fuel injection amount Qc is corrected based on the correction value Pr, and the drive output pulse Pout having the pulse width Tout is supplied to the gate of the FET 44. Thus, the fuel injection amount is appropriately adjusted in the fuel injection device in which the fuel injection amount is affected by the coil current that drives the fuel injection solenoid.
[0035]
FIG. 6 is a diagram showing a concept for obtaining the pulse width Tout of the drive output pulse Pout in the first embodiment of the present invention. As shown here, the correction pulse width calculation processing unit 71 determines the correction value Pr of the fuel injection amount Q based on the required fuel injection amount Qc and the coil current peak value Ip. This correction value Pr is added to or subtracted from the required fuel injection amount Qc in the calculator 72 (for example, an addition / subtraction unit), thereby obtaining the pulse width Tout of the next (or subsequent) drive output pulse Pout. The correction pulse width calculation processing unit 71 and the adder 72 are included in the microcomputer 43.
[0036]
FIG. 7 shows an example of a correction process when the control means constituting the fuel injection control device of the present invention includes a peak hold circuit that temporarily stores the coil current peak value Ip of the solenoid 46. The peak current value Ip of the coil is held in a peak current hold circuit (memory) provided in the microcomputer, and after the solenoid 46 is stopped driving, the microcomputer 43 acquires the acquired peak current value. Since the fuel injection amount correction value Pr corresponding to the required fuel injection amount Qc is obtained based on the peak current value and the drive output pulse is generated based on the correction value Pr, the required fuel injection amount Qc and the actual fuel injection amount The relationship becomes linear, and the fuel injection amount Q can be accurately corrected.
[0037]
In the present invention, as shown in FIGS. 4 and 5, the coil current during solenoid driving is sampled and held while the current peak value is updated, so that there is no strict restriction on the measurement timing. Further, according to the first embodiment, since a power supply voltage detection circuit, a constant current drive circuit, and the like as in the prior art are not required, the control circuit can be simplified and the number of parts can be reduced.
[0038]
Incidentally, the coil current peak value (measured value) Ip flowing through the solenoid 46 may vary greatly in the measured value due to the influence of noise or the like. If the drive output pulse Pout is output with a correction value that changes for each measurement, the fuel injection amount is not stable, resulting in inconvenience in engine drive stability. For this reason, the storage unit (not shown) of the microcomputer 43 stores a correction value obtained by averaging a plurality of latest correction values and a correction value obtained by averaging a plurality of correction values every predetermined driving cycle, and the average value is stored as a correction value Pr. You may make it use as. Further, an allowable value (width) with respect to the change of the correction value Pr is stored, and the correction value Pr obtained by averaging a plurality of correction values every predetermined driving cycle is compared with the correction value Pr calculated this time to detect this time. When the corrected value Pr does not exceed the permissible value, the correction value Pr is not changed, and the pulse width Tout of the drive output pulse Pout from the next time is obtained only when the correction value Pr detected this time exceeds the permissible value. Correction processing may be performed.
[0039]
FIG. 8 shows an example of a control processing flow for adjusting the drive (stop) time of the solenoid 46 based on the coil current value immediately before stopping the solenoid drive. Here, the correction value Pr is calculated using the coil current value Ir detected immediately before the solenoid 46 stops driving, and based on this, the required drive pulse Pw corresponding to the required fuel injection amount Qc is corrected. As in the example of FIG. 8, the correction value Pr is calculated using the coil current value Ir detected immediately before the solenoid drive is stopped. The coil current after the drive of the solenoid 46 is started is shown in FIGS. 4 and 5. As shown, since it usually increases with the passage of time, the coil current immediately before stopping the driving of the solenoid 46 is almost the peak current. Therefore, even if the coil current value Ir detected immediately before the solenoid 46 stops driving is handled as a peak current, no problem occurs.
[0040]
Therefore, in this case, the microcomputer 43 (FIG. 2) does not require the peak current value hold circuit as described in FIG. 7, and detects the current Ir of the solenoid 46 immediately before the solenoid 46 is stopped. Since the microcomputer 43 itself stops the drive of the solenoid 46 via the FET drive circuit 45 (FIG. 2), the timing setting immediately before the stop of the solenoid drive is easy, and problems such as a sampling timing shift do not occur.
[0041]
FIG. 9 shows the correction value Pr of the solenoid drive pulse in the correction process based on the coil current peak value Ip (including the “coil current value immediately before stop immediately before driving”) during solenoid driving according to the present invention described above. FIG. As shown in the figure, in the memory 8 in the microcomputer constituting the present invention, for example, the horizontal axis represents the coil current peak value Ip, the vertical axis represents the required fuel injection amount Qc, and various coil current peak values Ip. And a correction value map in which a correction value Pr corresponding to a combination of the required fuel injection amount Qc is mapped. The correction value Pr corresponding to the combination of the peak value Ip of the coil current and the required fuel injection amount Qc is obtained in advance through experiments or the like. As will be described later, such a correction value map may be a two-dimensional display map or a three-dimensional display map as long as there are a plurality of variable elements.
[0042]
According to the first embodiment of the present invention described above, the drive output pulse Pout for actually turning on and off the FET 44 that drives the solenoid 46 has the required fuel injection amount Qc and the peak value Ip of the coil current. Therefore, the relationship between the required fuel injection amount and the actual fuel injection amount becomes linear in the electromagnetic fuel injection pump that injects fuel while pressurizing the fuel, and the required fuel injection amount can be corrected accurately.
[0043]
In the present invention, as shown in FIGS. 4 and 5, the solenoid driving time is adjusted based on the peak value Ip of the coil current flowing through the solenoid 46. Therefore, since a relatively large current value is measured, there is an advantage that measurement errors are reduced.
[0044]
(2) Second embodiment of the present invention
Next, a case where the fuel injection method according to the second embodiment of the present invention is applied to the electromagnetic fuel injection system having the configuration shown in FIG. 1 will be described as an example. The description of the configuration of the electromagnetic fuel injection system is omitted because it overlaps with the previous first embodiment.
[0045]
Here, in the second embodiment, the inclination correction value represented by the ratio between the increase in the required fuel injection amount Qc and the increase in the solenoid drive output pulse width, and the fuel injection from the start of the solenoid drive. The drive output pulse width Tout is obtained by adding the corrected invalid time to a value obtained by multiplying the required fuel injection amount Qc by the inclination correction value based on the corrected invalid time until the start of.
[0046]
FIG. 10 shows the relationship between the fuel injection amount Q and the pulse width Tout of the solenoid drive output pulse Pout in the electromagnetic fuel injection system according to the second embodiment. As shown in FIG. 10, the fuel injection amount Q remains zero until the pulse width becomes zero (Toffset), and thereafter, there is a value of the fuel injection amount Q as the pulse width increases. It increases with the slope Td.
[0047]
The predetermined period (Toffset) after the start of driving of the solenoid 46 is a time during which actual fuel injection does not start, and is referred to as an invalid time since it does not affect the injection amount. This invalid time Toffset is also a fluctuation value influenced by the peak value Ip of the coil current. Therefore, in order to perform more appropriate fuel injection with respect to the fuel injection amount Q, it is necessary to correct this Toffset as well. In FIG. 10, the slope Td is the ratio between the increase in the required fuel injection amount QC and the increase in the drive output pulse width of the solenoid, and is referred to as a slope correction value Td in the present application. When the Td and Toffset are used, the pulse width Tout of the drive output pulse Pout necessary for accurately injecting the required fuel injection amount Qc is expressed by the equation [Tout = Qc × Td + Toffset].
[0048]
By the way, the invalid time Toffset varies depending on the magnitude of the coil current as described above, and therefore can be expressed as a function of the peak value Ip of the coil current. That is, the corrected invalid time Toffset value corresponding to the peak value Ip of the coil current is obtained. The corrected invalid time Toffset value is obtained, for example, from a two-dimensional display map in which the Toffset value is mapped to the peak value Ip of the coil current. This map is obtained in advance by experiments or the like.
[0049]
Further, when the relationship between the required fuel injection amount Qc and the drive output pulse width Tout is linear, the inclination correction value Td is a function of the peak value Ip of the coil current as in the invalid time Toffset. Therefore, the value of the inclination correction value Td is obtained from, for example, a two-dimensional table map in which the value of Td is mapped to Ip. However, when the relationship between the required fuel injection amount Qc and the drive output pulse width Tout is not linear, the inclination correction value Td is a function of the peak value Ip of the coil current and the required fuel injection amount Qc. Therefore, in this case, the inclination correction value Td is obtained using a three-dimensional display map in which the value of the inclination correction value Td is mapped to the peak value Ip of the coil current and the required fuel injection amount Qc. These maps are obtained in advance by experiments or the like.
[0050]
FIG. 11 shows an example of an injection amount characteristic graph showing the relationship between the actual fuel injection amount Qout at various coil current peak values and the pulse width Tout of the drive output pulse Pout for the final fuel injection. The injection amount characteristic graph shown in FIG. 11 indicates that the larger the peak value Ip of the coil current is, the shorter the invalid time is and the more fuel injection occurs for the same drive output pulse width. .
[0051]
FIG. 12 is a second conceptual diagram showing how to obtain the pulse width Tout of the corrected drive output pulse Pout in the second embodiment. Here, as shown in the figure, first, the multiplier 75 multiplies the required fuel injection amount Qc and the inclination correction value Td. The inclination correction value Td is obtained from the map 81 based on the peak value Ip of the coil current.
[0052]
Next, the adder 76 adds the invalid time Toffset to the value of Qc × Td. As the invalid time Toffset, the corrected invalid time Toffset obtained from the map 82 based on the peak value Ip of the coil current is used.
[0053]
In this way, the drive output pulse width Tout for the final fuel injection is obtained. Here, the multiplier 75 and the adder 76 are included in the microcomputer 43. The map 81 and the map 82 are stored in a data storage unit in the microcomputer 43.
[0054]
According to the second embodiment of the present invention described above, the inclination correction value Td is obtained based on the peak value Ip of the coil current or based on the peak value Ip of the coil current and the required fuel injection amount Qc. The invalid time Toffset corrected based on the peak value Ip of the coil current is obtained, and the pulse width Tout of the drive output pulse Pout for the final fuel injection is calculated using the corrected invalid time Toffset and the inclination correction value Td. Will be corrected.
[0055]
Thus, even when the relationship between the required drive pulse Pw and the fuel injection amount Q is not linear in the electromagnetic fuel injection pump that injects fuel while pressurizing, the fuel injection amount Q can be corrected appropriately. Further, in the case of a fuel injection device in which the relationship between the drive output pulse width and the fuel injection amount is linear, the inclination correction value Td and the corrected invalid time Toffset can be obtained from the two-dimensional map. There is an advantage that the calculation for obtaining the correction value is simplified and the amount of memory used by the map is reduced compared with the case of using the correction.
[0056]
(3) Third embodiment of the present invention
FIG. 13 is a diagram for explaining a control mechanism of the fuel injection control apparatus according to the third embodiment. As shown in FIG. 13, this control mechanism is connected to the electromagnetic fuel injection system shown in FIG. _B And a power supply voltage detection circuit 49 for supplying the detected value to the microcomputer 43 is added. Other configurations are the same as those shown in FIG.
[0057]
FIG. 14 shows an example of a correction process control flow according to the third embodiment. When the engine is started, that is, when the fuel injection solenoid 46 is driven for the first time, since there is no previous fuel injection cycle, the previous fuel injection cycle referred to obtain the inclination correction value Td and the corrected invalid time Toffset There is no coil current peak value Ip data at. The same applies to the case where the drive of the solenoid 46 is resumed after the fuel injection is interrupted by a fuel cut for idling stop or the like due to a fuel cut or a signal waiting when a vehicle equipped with this engine goes down a hill. In addition, when starting the engine such as when the battery capacity is small, the power supply voltage V _B May be extremely reduced, and the microcomputer may be reset, making it impossible to refer to the Ip data at the previous fuel injection.
[0058]
Therefore, in the third embodiment, the power supply voltage V is detected by the power supply voltage detection circuit 49 only when the engine is started or when the solenoid 46 is driven again after the fuel injection is interrupted due to fuel cut or the like. _B And the inclination correction value Td and the corrected invalid time Toffset are obtained based on the detected value.
[0059]
Although not particularly shown, the power supply voltage V _B A map in which the invalid time Toffset corrected for the power supply voltage V _B A map in which the inclination correction value Td is mapped to is obtained in advance through experiments or the like and stored in a storage unit in the microcomputer.
[0060]
Power supply voltage V _B As described above, the drive output pulse width Tout is obtained by the equation represented by [Tout = Qc × Td + Toffset] using the inclination correction value Td obtained based on the detected value and the corrected invalid time Toffset. This is the same as in the second embodiment.
[0061]
According to the third embodiment described above, at the time of the first driving when the solenoid 46 is driven again after the fuel injection is interrupted at the time of starting the engine and at the time of fuel cut, the power supply voltage V _B Since the pulse width Tout of the drive output pulse Pout for the final fuel injection is corrected based on the detection of this, and otherwise, based on the peak current Ip detected during the previous fuel injection, the third As in the first embodiment, the fuel injection amount Q can be accurately corrected in the electromagnetic fuel injection pump that injects fuel while pressurizing it.
[0062]
Furthermore, when the relationship between the pulse width Tout of the drive output pulse Pout and the fuel injection amount Q is linear, the map used for the correction calculation is two-dimensional, so that the correction calculation is simplified, There is an advantage that the memory usage by the map is reduced.
[0063]
(3) Fourth embodiment of the present invention
Next, a case where the fuel injection method according to the fourth embodiment of the present invention is applied to the electromagnetic fuel injection system shown in FIG. 1 will be described as an example. The fourth embodiment of the present invention to be described below is common in concept to the second embodiment of the present invention described above, but is a more specific example of the second embodiment. is there.
[0064]
The control configuration according to the fifth embodiment of the present invention is the same as the configuration shown in FIGS.
[0065]
FIG. 15 shows an example of a correction process control flow according to the fourth embodiment of the present invention. Here, the drive output pulse width of the solenoid 46 is controlled using the two correction maps 1 and 2 so as to perform accurate fuel injection with respect to the required fuel injection amount. More specifically, for example, the correction value 1 corresponding to the coil current peak value Ip from the inclination correction value Td represented by the ratio to the increase in the required fuel injection amount Qc and the correction map prepared in advance based on the intercept. And the correction value 2 is selected, and the correction value 2 is added to the value obtained by multiplying the required fuel injection amount Qc by the inclination correction value 1 to obtain the pulse width Tout of the drive output pulse Pout for the final fuel injection. .
[0066]
FIG. 16 shows an example of fuel injection quantity characteristics in the electromagnetic fuel injection system shown in FIG. Here, the vertical axis represents the injection amount value, and the horizontal axis represents the drive output pulse width value. The injection amount characteristic obtains the actual fuel injection amount while changing the pulse width Tout of the drive output pulse Pout at various coil current peak values Ip based on a predetermined power supply voltage value. FIG. 16 shows a state where the injection amount value Q changes with a certain slope Td with respect to the drive output pulse width value Tout at various coil current peak values Ip. The slope and intercept of the linear function are obtained from the characteristic values, and the correction value 1 and the correction value 2 are obtained by calculation from this combination. These measurement data are measured in advance by experiments or the like and stored in the storage unit.
[0067]
Here, the correction value 1 and the correction value 2 are calculated by the following calculation formula.
[0068]
[Correction value 1 = reference inclination / inclination]
[Correction value 2 = intercept / slope]
FIG. 17 shows an example of a correction map generated from the example of the injection amount characteristic shown in FIG. 16 and stored in the storage unit of the microcomputer 43. The correction value 1 and the correction value 2 corresponding to the combination of the coil current peak value Ip, the slope, and the intercept are calculated from the measured values by the above formula, and are associated with the combination of the coil current peak value Ip, the slope, and the intercept. Such a correction map is created. The correction map created in this way is stored in the storage unit of the microcomputer.
[0069]
By the way, the correction value map shown in FIG. 17 is a three-dimensional display map by expressing the correction value Pr as, for example, the height in a direction orthogonal to both the vertical axis and the horizontal axis.
[0070]
The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, in the first embodiment, the arithmetic unit that applies the pulse width correction value Pr to the required fuel pulse Pw corresponding to the required fuel injection amount Qc is not limited to an adder, but a subtractor, multiplier or divider, or These combinations and other calculations may be performed.
[0071]
In addition, the present invention is not limited to an electromagnetic fuel injection system, and can be applied to a fuel injection device including a fuel supply pressure regulator having a characteristic in which the relationship between a solenoid drive pulse width and a fuel injection amount is relatively linear. is there. This is because even in such a fuel injection device, the operation characteristics such as the operation start time (invalid time) of the drive solenoid vary depending on the coil current value, temperature, and the like.
[0072]
【The invention's effect】
As described above, the present invention measures the coil current value flowing through the solenoid immediately before stopping the driving of the fuel injection solenoid or the peak current value during driving of the solenoid, and based on the peak current value, Correct and adjust the solenoid drive stop timing. Here, the correction is determined in advance based on the peak current value and the required fuel injection amount for the solenoid, or for various combinations of the peak current value and the required fuel injection amount for the solenoid. The correction value selected according to the combination is used.
[0073]
Thus, the present invention realizes that the drive stop timing of the solenoid whose fuel injection amount is affected by the coil current is appropriately corrected and adjusted in accordance with the required fuel injection amount. Here, in the present invention, the supply of an appropriate fuel injection amount is realized by measuring the peak current immediately after the start of driving of the solenoid or immediately before the stop of driving, and obtaining a correction value based on the measured value.
[Brief description of the drawings]
FIG. 1 shows a configuration example when a fuel injection control method and a fuel injection control device according to the present invention are applied to an electromagnetic fuel injection system.
FIG. 2 shows an example of a control mechanism of the fuel injection control device according to the first embodiment of the present invention.
FIG. 3 shows an example of a correction processing control flow based on peak current in the first embodiment of the present invention.
FIG. 4 shows a correction processing timing chart according to the present invention.
5 shows a relationship among a required drive pulse corresponding to a required fuel injection amount, a peak current reading process, a coil current, a correction value, and an actually output drive pulse in the timing chart shown in FIG.
FIG. 6 is a conceptual diagram showing how to obtain the pulse width of a drive output pulse in the first embodiment of the present invention.
FIG. 7 shows an example of a correction processing control flow having a peak hold circuit in the first embodiment of the present invention.
FIG. 8 shows an example of a correction process control flow based on a current value immediately before stopping the solenoid drive.
FIG. 9 is a diagram conceptually illustrating how to obtain a correction value Pr for a drive output pulse of a solenoid.
FIG. 10 shows a relationship between a fuel injection amount Q and a solenoid drive output pulse width T in a fuel injection control system according to a second embodiment of the present invention.
FIG. 11 is a graph showing an injection amount characteristic in the fuel injection device.
FIG. 12 is a conceptual diagram showing how to obtain a corrected drive output pulse width Tout in the second embodiment of the present invention.
FIG. 13 shows an example of a control mechanism of the present fuel injection control device including a power supply voltage detection circuit.
FIG. 14 shows an example of a correction processing control flow in the third embodiment of the present invention.
FIG. 15 shows an example of a correction processing control flow in the fourth embodiment of the present invention.
FIG. 16 shows an example of injection quantity characteristics of electromagnetic pressurization fuel injection.
FIG. 17 shows an example of a correction map generated from an example of injection quantity characteristics according to the present invention and stored in a storage unit of a microcomputer.
FIG. 18 shows an example of a control mechanism of a conventional fuel injection control device.
[Explanation of symbols]
Ip peak current
Pr correction value
Pout drive output pulse
Qc Required fuel injection amount
Pw Required drive pulse corresponding to required fuel injection amount Qc
Tw Pulse width of requested drive pulse
Td Tilt correction value
Toffset invalid time (corrected invalid time)
Tout Drive output pulse width
6 Current detection circuit
41 battery
V _B Battery 41 voltage (power supply voltage)
43 Microcomputer
44, 48 FET
46 Solenoid (coil)
49 Power supply voltage detection circuit
50 capacitors
55 Feedback circuit

Claims (12)

A method of controlling an electromagnetic fuel injection pump that pressurizes and injects fuel,
Said measuring the peak value of the coil current flowing through the solenoid in the driving stop just before the fuel injection pump is corrected by adjusting the driving stop timing of the solenoid for driving the start and stop of the fuel injection pump on the basis of the peak value A fuel injection control method. A method of controlling an electromagnetic fuel injection pump that pressurizes and injects fuel,
A step of driving a solenoid for driving the fuel injection pump for a predetermined time;
A step of measuring a peak value of a coil current value flowing through the solenoid immediately before the solenoid stops driving;
A step of obtaining a correction value for correcting the drive stop timing of the solenoid based on the peak value ;
And a step of adjusting the drive stop timing of the solenoid using the correction value. The correction, the fuel injection control method according to claim 1 or 2, characterized in that a correction value which is determined on the basis of said peak value and the required fuel injection amount. The correction is determined in advance for various combinations of the peak value and the required fuel injection amount, and a correction value selected according to the combination is used. Fuel injection control method. Correction of the solenoid drive stop timing is as follows:
A step of obtaining an inclination correction value represented by a ratio between an increase in the required fuel injection amount and an increase in the drive output pulse width of the solenoid, which is determined according to one or both of the peak value and the required fuel injection amount;
A step of obtaining a corrected invalid time from the start of driving of the solenoid determined according to the peak value to the start of fuel injection;
A step of obtaining a correction value obtained by adding the corrected invalid time to a value obtained by multiplying the required fuel injection amount by the inclination correction value, and each step.
The fuel injection control method according to claim 1, wherein the stop timing of the solenoid is adjusted using the correction value.   In setting the driving time of the solenoid at the time of starting the engine or at the time of the first driving when resuming the fuel injection once interrupted, the power supply voltage applied to the solenoid is measured, and based on the measured value, the power supply voltage is measured. The fuel injection control method according to claim 1, wherein the drive stop timing of the solenoid is corrected. A control device for a fuel injection device using an electromagnetic fuel injection pump that pressurizes and injects fuel,
A drive means for the solenoid for the electromagnetic fuel injection pump ;
Measuring means for measuring the peak value of the coil current in the drive stop immediately before the solenoid,
It obtains a correction value for correcting the driving stop timing of the solenoid based on the peak value, and control means for adjusting the timing of the drive stop of the solenoid by the solenoid driving unit by using the correction value,
A fuel injection control device comprising:   The fuel injection control device according to claim 7, further comprising a feedback circuit for returning energy released from the solenoid to the power source when the solenoid is stopped.   The fuel injection control device according to claim 8, wherein the feedback circuit includes a capacitor that charges energy released from the solenoid when driving of the solenoid is stopped. 10. The fuel injection control device according to claim 7, wherein the correction value is determined based on the peak value and a required fuel injection amount for the solenoid. 10. The correction value is determined in advance for various combinations of the peak value and the required fuel injection amount, and is selected according to the combination. A fuel injection control device according to claim 1. The controller is
Storage means for storing the peak value ;
An inclination correction value expressed by a ratio between an increase in the required fuel injection amount and an increase in the drive output pulse width of the solenoid, which is determined according to one or both of the peak value and the required fuel injection amount stored in the storage means. A means of seeking
Means for obtaining a corrected invalid time from the start of driving of the solenoid determined according to the peak value stored in the storage means to the start of fuel injection;
And means for obtaining the correction value obtained by adding the corrected invalid time to a value obtained by multiplying the required fuel injection amount by the inclination correction value,
The fuel injection control device according to any one of claims 7 to 9, wherein the stop timing of the solenoid is adjusted using the correction value.

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