JPS6043146A - Fuel injection apparatus - Google Patents

Abstract

PURPOSE:To control the air-fuel ratio of an internal combustion engine accurately, by correcting fluctuation or variation of the injection quantity of fuel by providing an air-flow sensor for detecting the quantity of intake air supplied to the engine and a control unit for controlling the driving signal for a fuel injector. CONSTITUTION:An air-flow sensor 5 detects the quantity of air supplied to an internal combustion engine 3, and the output of said sensor 5 is furnished to a control unit 4. A fuel injector 1 has an actuator for pressurizing fuel that is formed in a unitary manner. The control unit 4 controls the driving signal for the fuel injector 1 to keep a predetermined relationship between the integral value of the air quantity and that of the driving quantity of the fuel injector 1 within a prescribed period. Thus, since fluctuation or variation of the injection quantity of fuel is corrected, it is enabled to control the air-fuel ratio accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for injecting and supplying fuel to an internal combustion engine using a pressurizing actuator such as an electrostrictive actuator.

Conventionally, fuel injectors that have an integrated pressurizing actuator such as an electrostrictive actuator have been known, but this actuator is susceptible to fluctuations in the fuel injector due to differences between individual parts, temperature changes, aging, etc., and the air-fuel ratio may change. was there.

This invention was made in view of the points mentioned in 2.
'4 114 yen The purpose is to correct fluctuations in injection amount and perform accurate air-fuel ratio control.

The above object is achieved by controlling the drive of the fuel injector by the control unit so that the integral value of the amount of air supplied to the engine and the drive amount of the first fuel injector maintain a predetermined relationship.

Examples of the present invention will be described below.

The structure of the fuel injector 1 will be explained with reference to FIG.

The fuel injector 1 has an electrostrictive actuator 2 instead of a pressurizing actuator, and is operated by expansion and contraction of this actuator. The electrostrictive actuator 2 is a columnar stack of thin disc-shaped elements having an electrostrictive effect, and when 500V is applied to each element in the thickness direction, it expands by about 0.5 μm.
Conversely, when a voltage of -500V is applied, it expands and contracts by about 0.5 μm. However, if 100 lever elements are laminated, 100 times the expansion and contraction can be obtained. The element is a ceramic made of sintered titanic acid, zirconate, and lead, such as PZT, and silver electrodes are formed on both sides of the element to apply voltage. Lead cotton 201 is used to apply the voltage. This lead wire is connected to the casing 1 of the fuel injector 1 through the grommet L-202.
01 and is taken out to the outside and connected to the control unit 4. The expansion and contraction motion of the electrostrictive actuator 2 is directly transmitted to the piston 203, causing it to reciprocate.

The piston 203 slides within the cylinder 102 of the casing 101, expands and contracts the volume of the pump chamber 103, and performs a pumping action. A disc spring 104 is installed in the pump chamber 1°3.
is provided to urge the piston 203 in the direction of expansion and contraction of the electrostrictive actuator 2. This is because the contraction force iJ of the electrostrictive actuator 2 is weaker than the expansion force. When the pump chamber 103 expands, external fuel is sucked in through the reverse 11-valve 105. At this time, the suction 1I8106 is provided in the wall that constitutes the casing 101. Further, the check valve 105 is provided within a distance piece 108 for separating the pump chamber 103 and the injection valve 107 i'jlt.

The injection valve 107 is an outward-opening single hole consisting of a nozzle body 109 and a needle 110.
iJ: The spout 112 is urged to close by the III spring 111. However, when the pump chamber lO3 contracts, the fuel pumped through the discharge port 117 of the distance piece 108 is injected into the casing 101 and the distance piece. The nozzle body 109 and the nozzle body 109 are stacked in the same order and are pressed and fixed in the axial direction by the bag-shaped lower casing 113.

The lower casing 113 and the casing 101 are coupled together by snapping. A hole 114 is provided at the lower end of the lower casing 113, and a nozzle 112 is exposed. The lower casing 113 is further provided with a screw 115 on its outer periphery, and is fixed to the internal combustion engine 3 by this. In addition, 116 is a ring, 119 is a knock bottle, and 118 is a casing 101.
This is the fuel inlet installed in the

The amount of injection per injection by the fuel injector 1 is determined by the stroke of the electrostrictive actuator 2, and the stroke is determined by the applied voltage. Now, increase the applied voltage from -500v to +5
When changed to 00V, it shall be 5 mm 311j7U・I. The injection pressure is determined by the diameter of the nozzle 112, the strength of the disk spring 111, and the amount of injection, but now 500V is applied and injection T of 5 to 3! 100 kg/ct toil.

In FIG. 2, reference numeral 3 denotes a well-known four-stroke gasoline internal combustion engine, which includes an intake valve 31, an exhaust valve 32, an intake pipe 33, an exhaust pipe 34, and the like. A throttle valve 35 is provided inside the intake pipe 33, and a fuel injector 1 is provided on the pipe wall. The fuel injector 1 may be installed upstream or downstream of the throttle valve 35. The intake pipe 33 communicates with the atmosphere via an air cleaner 36, and an air amount sensor 5 is provided downstream of the air cleaner 36.

There are many types of air sensors 5 that have been put to practical use, and any of them may be used. For example, one that uses a hot wire wind speed needle and outputs a voltage proportional to the wind speed, that is, proportional to the amount of intake air, is used. The principle and structure of a hot-wire anemometer are well known and will not be described here. The output of the sensor 5 is manually input to the control unit 1-4.

Fuel 4゛・1 injector 1 has a air pump 7 and a filter 8
Fuel 1 is supplied from the fuel tank 9 through the fuel tank 9.

The soy bomb 7 is a general type (J diaphragm or electromagnetic type is used, and the discharge pressure is 0.5
k+r/cn! is set to Although not shown,
It is effective to provide a reservoir or a rubber regulator between the finido bomb 7 and the fuel injector I.

It is also possible to eliminate the feed pump 7 and provide a sufficient head difference between the fuel tank 9 and the unit injector 1, or to pressurize the inside of the fuel tank 9.

JJ31 l! The cylinder block +3 is provided with a water jacket, and a water temperature sensor 62 for detecting the cooling water temperature is provided therein. Water temperature sensor 62
The signal is input to the control unit 4. The exhaust pipe 34 is provided with an 02 sensor 63, which detects the concentration of 02 in the exhaust gas, and outputs a rich signal when there is no or too little 02 in the exhaust gas, and a lean signal when there is too much 02. is sent to the control unit 4.

The control unit 4 uses a frequency proportional to the output of the air amount sensor 5 as a fundamental frequency, and uses a water temperature sensor 62 at this fundamental frequency.
The pulse fuel injector 1 is driven at the frequency obtained by supplementing the signal from the 02 sensor 63. Furthermore, the control unit 4 compares the integral value of the output of the air amount sensor 5 and the integral value of the drive current of the fuel injector 1 during a predetermined period,
A function that corrects deviations in the air-fuel ratio due to changes in the characteristics of the electrostrictive actuator 2 by successively correcting the proportionality constant when calculating the fundamental frequency from the output signal of the sensor 5 so that the two have a predetermined relationship. has.

Here, when the output from the air amount sensor 5 corresponds to an air amount of 5 g/sec and the fuel is gasoline with a specific gravity of 0.74, the control unit 4 controls the fuel injector 1 at a fundamental frequency of 92.
Drive at Hz. The amount of fuel at this time is 5'mi 3x
92/sec and 460 m11”, i.e. 0.34. g/sec and the air/fuel ratio is 51
The stoichiometric air-fuel ratio is 0.34, or 14.7. Similarly, if the air amount is 10 g/s e C, the frequency is 184 Hz, and if the air ff is 120 g/sec, it is 368 tl z, air'
For H30g/sec, the control unit 4 controls the fuel injector 1 to maintain the air-fuel ratio at the stoichiometric air-fuel ratio using 552 Hz as the fundamental frequency. This is because correction is made using the iron fundamental frequency, the signal from the water temperature center 62, and the signal from the 02 sensor 63.

In this way, there is a proportional relationship between the air sensor output and the fundamental frequency, and the proportionality constant is 92 Hz / 5 g / s.
e c = 18.4 Hz / g / se
It is c.

After calculating the fundamental frequency, correction is performed using the water temperature sensor 63. Instead, a correction is made based on the water temperature.This correction method involves, for example, setting an appropriate increase ratio in advance in a bench test or the like according to the water temperature, and recording this data in the control unit 41a. The control unit 4 determines an increase ratio for the water 61 according to the water temperature detected by the sensor 62, and multiplies it by the basic frequency, thereby driving the fuel injector 1 at a frequency corrected according to the water temperature. ?7! Increase ratio at 20°C is 1.5
is set in advance, and when the air amount is 10 g/'sec, the fundamental frequency is 1841 (z x increase ratio.

Unit injector I at 1, 5 = 276 Hy! It will move 51 times. When the water temperature reaches 60° C. or higher, it is assumed that the internal combustion engine 3 has been warmed up, and the water temperature correction 1 is not performed. Instead 02 sensor 6
Perform the correction according to 3.

The correction by the 02 sensor 63 is multiplied by the fundamental frequency if
This is done by increasing or decreasing the f positive coefficient according to the rich/lean depression detected by the 02 sensor 6.3.

That is, when the output of the 02 sensor 63 is determined to be rich, the correction coefficient is gradually reduced at a rate of, for example, 0.04/sec, and conversely, by multiplying the fundamental frequency determined to be lean, when the output is rich, Since the driving frequency gradually decreases, the air-fuel ratio A/F tends toward lean, and conversely, when the driving frequency is lean, the driving frequency gradually increases, so the A/F changes toward rich. In this way, correction can be made so that the air-fuel ratio always converges to the stoichiometric air-fuel ratio.

Next, the control unit 4' will be explained. In FIG. 3, a sensor 5 outputs a voltage proportional to the amount of intake air, and for example, when the amount of intake air is 10 g/secC, it outputs a voltage of 1. 401 is the first A/D conversion circuit, and the sensor 5
The signal is A/D converted and converted into a 16-bit digital signal, which is connected to the pass line 4'34. 402 is a second A/D conversion circuit that converts the output signal of the water temperature sensor 62 into A/D conversion circuit;
/Di to convert it into a 16-bit digital signal and connect it to the pass line 434. 403 is a vertical circuit that compares and shapes the output signal of the 02 sensor 63 at a predetermined level, and when the oxygen concentration in the exhaust gas is high, it outputs an O level and Le lean signal, and when the oxygen concentration in the exhaust gas is low, it outputs a Lebel signal. The signal is output to pass line 434.

A clock generation circuit 404 generates clock signals φl, φ2, and φ3 with stable frequencies. The frequency of each clock signal is, for example, φ+ = IK I(,z.

ψ2 = 100)1z, φ3 = 500 K
It is Hz.

The black/2 signal φ1 is the CPU interrupt input I, which will be described later.
NT2, and the clock signal ψ2 is also connected to the interrupt input I N'T3.

405 is a 16-bit latch circuit that latches and outputs the drive cycle T calculated by the CPU 430.

Reference numeral 406 denotes a 16-bit binary counter, whose reset input is connected to the comparison output of a digital comparator 407 (7), and whose clock input is connected to the clock signal φ3 from the clock generation circuit 404. Therefore, the contents of the binary counter 406 indicate the elapsed time from the time when the previous output from the digital comparator 407 was generated. Let this be t.

407 is a 16-bit digital comparator, and the driving period T of the fuel injector l, which is the output of the latch circuit 405, is
and the output of the binary counter 406, and when t>T, a Luher signal is generated.

This output signal is connected to the reset input of the binary counter 406 and to the interrupt input 1NT1 of the CPU 430 and the one-shot multi 408.

Since the pulse time width of the output signal of the digital comparator 407 is short, the multi-'408 is provided to widen the pulse time width to a certain period of time, for example, 4.00 psec. 409 is a drive circuit that connects the electrostrictive actuator 2 of the unit injector 7 with a one-shot multi 40
When the signal No. 8 is level, -1-500V is applied, and when the signal is 0 level, -500V is applied.

411 is a first integration circuit that integrates the output signal of the airflow meter 5; 412 is a third A/D conversion circuit;
The output signal is A/D converted and connected to a pass line 434. A second integrating circuit 413 integrates the drive current output signal of the drive circuit 409, and when the reset signal becomes a level, the integration is initialized and the output becomes 0. 41
4 is a fourth A/D conversion circuit that A/D converts the output signal of the integrating circuit 413, converts it into a 16-bit digital signal, and outputs it to the pass line 434. 415 is an l-bit latch circuit that latches the integrated cent signal from the CPU 430 and outputs it. This output is connected to the reset power of the integrating circuit 411 and the integrating circuit 413. 416 is a 500-decimal counter, the match signal of comparator 407 is connected to its clock input, and this match signal
Every time a 00 pulse arrives, one rubel pulse is output.

This output is connected to the interrupt input INT4 of the CPU 430.

Reference numeral 417 is a constant voltage circuit that stabilizes the @ source supplied from the on-board battery 10 via the key switch 11 and supplies it to each part, and also provides ±500 voltage for driving the electrostrictive actuator.
A high voltage of v is supplied to the drive circuit 409. battery 10
A stabilized voltage is always supplied to the RAM 432 through the resistor 418 and the tsuna diode 419.1 capacitor &20, regardless of the switch 11, so that its contents are not lost. 430 is a 16-bit CPU, and its interrupt input NTl receives the output signal of the digital comparator 407, and the output signal φ1 of the digital comparator 407 goes to INT2.
However, the clock signal ψ2 is applied to INT3, and the clock signal ψ2 is applied to INT4.
The output of the decimal counter 416 is connected. The interrupt priorities are lNTl, INT2, INT3, I-
Processing is prioritized in the order of NT4. 4
31 is a ROM that stores program and data.
, 432 is a RAM, which is backed up by a battery as described above.

Next, the 8-integrator circuit will be explained. Figure 4 shows the drive circuit 4.
09 is a circuit diagram of a first integrating circuit 411, a second integrating circuit 413, and their surroundings. AI is an amplifier and resistor R1
, R2, and amplifies the output signal of the air amount sensor 5 with a gain determined by R2. In this embodiment, the gain is -1. A
2 is an operational amplifier, which constitutes an integrator with a time constant determined by a resistor R3 and a capacitor CI;
The output signal of is integrated and output. In this example, the resistance R
3 is 2m71 and Ω, and the capacitor C+ is 10μF. SL is an analog switch that is electrically opened and closed, and the control is turned on and off to short-circuit the integrating capacitor C1, thereby initializing the integrator and setting the output to O. The output of the first integration circuit 411 is connected to a third A/D conversion circuit 412.

m2 integration times 1? &413 is a circuit similar to the first integrating circuit, and A3 is an operational amplifier that amplifies the drive current output signal with a gain determined by resistors R4 and R5. In this embodiment, the gain is -1. A4 is an operational amplifier, and resistor R
6 constitutes an integrator with a time constant determined by capacitor C2, and integrates and outputs the output signal of amplifier A3.

In this example, resistor R6 is 5Ω and capacitor C2 is 1Ω.
It is μF. S2 is an analog switch that is electrically opened and closed, and is closed when the control is at level, and short-circuits the integrating capacitor C2, so that the output of the integrated quantity is set to O. The output of the second integration circuit 413 is A/D
It is connected to the conversion circuit 414.

In the drive circuit 409, the constant voltage power supply circuit 417
500■ is always stored in the capacitor C3, and -500■ is always stored in the capacitor C4. These capacitors are provided so that the power supply voltage does not fluctuate due to surge power when driving the electrostrictive actuator. One shot multi 40B
When the drive signal from
Transistor T1 is ONL through T-, and its collector current makes transistor T2 conductive through resistors R, +2, and R13, and current flows from +500V to electrostrictive actuator 2 through current control resistor R14. In this embodiment, the current control resistor R14 is 20Ω. On the other hand, when the drive signal from the one-shot sotomaruch 408 is at 0 level, the transistor T3 is turned on via the resistors R+s and R16, and its collector current turns on the transistor T1 via the resistors RI7 and RI8, and -500■ is the current control. It is connected to the electrostrictive actuator 2 via the resistor RI4.When the transistor T2 is turned on, +500■
The current flowing from to the electrostrictive acticoator 2 is detected by the current transformer TR, converted into a voltage signal, and connected to the first integration circuit 413.

In this example, the characteristics of the current transformer TR are 10A/
This is V.

The operation of the integrating circuit in the above configuration will be explained.

FIG. 5 is a waveform diagram of each part for explanation.

Now the drive signal from the one-shot multi 408 (Fig. 5 (A)
)) is input, the drive circuit 409 outputs +500V.
, generates a driving voltage of -500V- (FIG. 5(B)),
The electrostrictive actuator 2 is driven. At this time, the electrostrictive actuator has a peak value of 50A as shown in Figure 5(C).
A current of ゛ flows.゛Figure 5 (D) shows +50 of these.
This is the charging current waveform when a voltage of 0.0 cm is applied, that is, when the electrostrictive actuator 2 performs a pump operation. Details of this part are shown in FIG.

FIG. 6(A) shows the waveform of the actual charging current, and its time constant is determined by the current control resistor RI4 and the capacitance (1.5 μF) of the electrostrictive acticoator 2, and is 30 μsec. Thereafter, this is changed to a peak current of 50A1 as shown in FIG. 6(B).
Time width 40 μS e C.

Consider it by approximating it to a triangular wave. This current is converted into a triangular wave with a peak value of 5V and a time width of 40 psec by the current I/rance TR, and is input to the second integration circuit 413.

The second integration circuit 413 converts this drive current signal into the drive current signal as shown in FIG.
Integrate as shown in . -2Qm by integral
It will increase by V. If this is repeated 500 times, a voltage of 1O2 is finally obtained as the drive current integral value.

On the other hand, the first integrating circuit 411 similarly integrates the output signal (10 g/s e'c/V) of the air amount sensor 5. In this case, if the average value of the air amount is x g/sec, the output voltage of the air amount sensor 5 is 0. It becomes lx. As mentioned above, the driving frequency is 18.4. Hz/g/
Since the frequency is 18.4xHz when s e c, the time required to perform 500 integrations is 500/18°4xsec. Therefore, the final integrated value is 10V.

In this way, the electrostrictive actuator 2 is adjusted by a predetermined amount, that is, ±
When 500 ■ is applied, it expands and contracts by 50 μm, and when 5 Dragon 3 fuel is injected, both the driving current integral value and the air amount integral value are I.
OV, and the proportionality constant is -18, 4If z / g
/ sec Teraiko and Wakaru.

If the amount of expansion and contraction of the electrostrictive actuator 2 decreases due to some reason (for example, temperature change, secular change) and the injection amount decreases accordingly, the value of the drive current decreases, so its integral value will be less than IOV. Become. For example, the amount of expansion and contraction of the electrostrictive actuator 2 is 40 μm, and the injection 9
Assuming that the amount is also 4 dragons 3, the drive current peak value is 4.
Since it becomes OA, the drive current integral value decreases to 8■.

If the proportionality constant k remains at 18.4Hz/g/s e c, the air amount integral value remains at 10V, so CPU4
．． 30 is corrected to 23.0 Hz/g/sec by multiplying the proportionality constant k by 10/8 from the relationship between the two. If this is done, the next air amount integral value will be 8■, which matches the drive current integral value, which means that the correction has been made correctly.

Even if the amount of expansion and contraction of the electrostrictive actuator 2 becomes large, this can be corrected in the same manner as described above. For example, if the drive current integral value increases from IOV to 12■, the proportional constant is multiplied by 1.0/12 and becomes 15.33Hz/g/s.
By correcting to eC, the A/F can be maintained at the stoichiometric air-fuel ratio. The reason why the number of integrations is set as long as 500 is to detect the average variation in order to eliminate the influence of the 02 sensor feedback.

Next, the overall operation of the control unit 4 will be explained.

7 and 8 are time charts showing the states of each part for explanation, and FIGS. 9A to 9E are flow charts of the program. First, when the key switch 11 is turned on, power is supplied to the control unit 4 from the battery I.0, and a predetermined power is supplied to each circuit by the power supply circuit 417 to start operation. When the power is turned on, each side-loading routine is prohibited, and only the main routine shown in Figure f69A is activated.

The main routine checks whether the first time the power is turned on to the control unit 4 is the second time or later.

If this is your first time, the various parameters are not yet stored in the RAM 432, so initialize them to representative values for now. If it is the second time or later, the backed up RAM
Since the parameters are left in 432, this is not necessary. After initializing each part such as the t1 counter and the integrating circuit, interrupts are enabled and an idle loop is entered.

Next, consider the operating condition of the engine. 7NT2 shown in Figure 9C
The routine starts with the clock signal ψ+(IK
IIz). In this routine, first
Read the intake air amount data from the A/reconversion circuit 1zδ401. This value is the amount of intake air at the time the INT2 routine is started, and as is well known, the amount of intake air pulsates in accordance with each stroke of the engine. Therefore, it is necessary to calculate the average value during the period for which the fuel amount is calculated from the intake air amount. For this reason, the data on the amount of intake air during instantaneous R'JJ read by the INT2 routine is displayed every minute! 7 and store it in the RAM 432. This is ΣA (Fig. 7 (C
)). At the same time, the number of integrations N is increased by 1 for each INT2 routine, and is stored as data for calculating the average value described later (ΣΔ, N are initialized in the 1NT1 routine. The N T 2 routine returns and finishes processing.

The INT3 routine shown in FIG. 9D is activated by the clock signal φ2000112) shown in FIG. 8(A). First, water temperature data is read from the second A/D variable circuit 402. Next, check whether the water temperature is 6o'C or higher.
If it is less than 0°C, perform warm-up Jolt control based on water temperature. In this method, the increase ratio for each water temperature is recorded in advance in the ROM 431 in the form of a map in a bench test or the like, and the warm-up increase ratio is determined from the previous water temperature data by a supplementary N11 calculation.

The value thus obtained is stored in the RAM 43 as a correction coefficient P'.
2 and return. If the water temperature is 60° C. or higher, it is assumed that warm-up has been completed and no warm-up correction is performed. Instead, A/F feedback correction is performed using the 02 sensor 63. In this method, the correction coefficient P multiplied by the fundamental frequency is 02
This is done by increasing or decreasing the latch detected by the sensor 63, depending on the lean state.

The rich or lean state of the exhaust gas detected by the 02 sensor 63 is read from the shaping circuit 403, and if it is the beginning of the latch, a preset skip Wk K is determined from the correction coefficient P.
Subtract s shi to obtain P −K−s L.

In the subsequent rich state, the correction coefficient P is decreased to a certain set value Δ. For example, this rate is 0.04/s
If e is c, then the frequency of interrupt of INT3]
For 00 Ilz, ΔKL=0.0004/IQm
s e c, the correction coefficient is set to P to Δ every time it is determined to be rich at [NT'3. On the contrary, 02 sensor 6
When the signal No. 3 is lean, it is checked whether it is the beginning of lean, and if it is the beginning, a skip amount of KSR is added to the correction coefficient P to make p+KqR. If it is not the first time, the preset rate Δ■ (R increases the main 111 positive coefficient P, Article. For example, 111 If this rate is 0.06/sec, ΔKR = 0.OOO6/IQms e c The correction coefficient P is set to P+ΔKR every time it is determined to be lean in INT3.

Although not shown in the flowchart, the 02 sensor 63
The latch or lean state may continue for a long time when the temperature of the engine is low and it is not activated, or when the engine brake is applied to fuel and throat. At this time, a negative limit and a lower limit of the correction coefficient P are set in advance, a limit is applied so that the correction coefficient falls within this range, and if the rich or lean state continues for more than a certain set time, the strong ．． Control may also be performed to return the correction coefficient to 1.0 or a preset value. At the end of the INT3 routine, the correction coefficient P is stored in the RAM 432 and the process returns.

Next, the lNTl routine shown in FIG. 9B will be explained. lNTl is the comparator 407 shown in FIG. 7(,A).
That is, it is activated every time the electrostrictive actuator 2 is driven. The lNTl routine is a routine that calculates the average value of the intake air amount, calculates the fundamental frequency from this value, corrects it, and outputs it.

First, hΣA and the number of times of integration N, which have been integrated in the INT2 routine, are read out from the RAM 432, and λ-'ΣA'/N is calculated. This X corresponds to the average amount of intake air between the previous drive signal and the current drive signal (INTI). After this, in preparation for the next integration, ΣA=0 and N=0 are cleared. Next, calculate the fundamental frequency F from this intake air 1 uA. As described above, this can be determined by multiplying the intake air amount by the proportionality constant k (typical value 18, 4 I+z/g/sec).

However, the value of k is modified in the INT4 routine described later according to the amount of expansion and contraction of the electrostrictive actuator, and is stored in RAM4.
32 is listed as 1α. Next, this fundamental frequency 17 is
The correction coefficient P calculated in the INT3 routine is read out and multiplied by the previously determined fundamental frequency F to obtain the corrected drive frequency.

Finally, convert this frequency into a period or binary counter 40
It is converted into the pulse number T of φ2, which is the clock of 6, and outputted to the latch 405, and the process returns. From then on, comparator 4
07 is the output t of the binary counter 406 and the latch 4'0
5 and automatically generates a drive signal when t≧T. This drive signal is converted into a voltage of ±500 cm by a drive circuit 409 and drives the electrostrictive actuator 2.

Next, the INT4 routine shown in diagram 1lQE will be explained. The INT4 routine is activated every time the drive signal is output 500 times. First, water temperature data is read from the second A/D conversion circuit 402 and checked to see if it is 60°C or higher. 6
If the temperature is 0°C or higher, perform the following treatment. First, 3rd A/D
Read the air amount integral value EArq from the conversion circuit 412,
Next, from the fourth A/D conversion circuit 414, the drive current integral value E
Read C1''R. Thereafter, a reset signal for the integration capacitor of the launch circuit 415 is outputted to prepare for the next integration.

Air amount integral value EAI'R and drive current integral value E.

uR is compared, and if the absolute value of the difference is less than or equal to a certain constant ε, the proportionality constant can be left as it is, so the process returns without changing it. EAIR is more E. If it is larger than uR, the injection amount is smaller than the intake air amount, so the proportionality constant k is corrected. The correction method is as described above.
It is also possible to multiply the value of EAIR/EcuR,
Alternatively, for example, the number may be increased by 5 and 6. In any case, eventually EArR, F, and CuR converge to match, and the stoichiometric air-fuel ratio can be maintained. Also E
If A r R is smaller than ECIJ, R, the value of k is corrected in the same way. The new value of k is in RAM4
32 and then returns, and is used to calculate the fundamental frequency in the aforementioned NTI routine.

Furthermore, since the RAM 432 is backed up, its contents are saved even if the switch is turned off.
There is also a learning effect in that from the first time onward, the results of previous corrections can be used immediately. When the water temperature is less than 60° C., the air-fuel ratio A/F is not the stoichiometric air-fuel ratio, so the above-mentioned correction to the proportionality constant is not performed, and only the integral circuit is initialized and the process returns.

In this way, by correcting the value of the proportionality constant at predetermined intervals based on the relationship between the drive current integral value and the air amount integral value, it is possible to set a fundamental frequency that always maintains the stoichiometric air-fuel ratio. can.

In addition, in this example, a method was explained in which the integral value of the drive power source and the integral value of the air amount sensor output were compared and corrected by changing the driving frequency so that the two matched, but the frequency was not corrected. It's great to change the driving voltage. 10th
The figure shows an example in which the driving voltage is changed. E artificial R
If E is larger than uR, the CPU sends the previous EA to the D/A converter 440 to increase the drive voltage.
Calculate and set the value multiplied by IR/E cu R.

The outputs of the D/A converters are turned into voltages of ±50 times by stabilizing circuits 450 and 460, respectively, and supplied to the driving circuit.

When EAIR is smaller than ECuR, D/A
By reducing the value to converter 440 and lowering the drive voltage, the injection amount is reduced.

Another example is to make the drive current itself a constant current,
It can also be corrected by changing the constant current value or the energization time.

As explained above, the amount of expansion and contraction of a pressurizing actuator such as an electrostrictive actuator is indirectly detected by the integral value of the drive current, and controlled so that it has a predetermined relationship with the integral value of the intake air amount. Therefore, even if the characteristics of the pressurizing actuator change, the air-fuel ratio can always be accurately controlled, which is an excellent effect.

Furthermore, if the integration period is determined by the drive ratio, a nearly constant final integral value can be obtained regardless of the engine conditions, and there is no drop in accuracy.Furthermore, the integration period can be made sufficiently longer than the feedback period of the 02 sensor. 02
A/F pulsations due to sensor feedback are averaged, and changes in base A/F can be accurately detected.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing a fuel injector used in an embodiment of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the invention, Fig. 3 is a block diagram showing a control unit, and Fig. 4 is a sectional view showing a fuel injector used in an embodiment of the present invention. 5 to 8 are waveform diagrams to explain the operation, FIGS. 9A to 9E are flowcharts to explain the operation, and FIG. 10 shows another embodiment. FIG. 2 is a main part electrical circuit diagram shown. DESCRIPTION OF SYMBOLS 1... Fuel injector, 2... Electrostrictive actuator forming a pressurizing actuator, 4... Control unit, 5...
・Air amount sensor. Representative Patent Attorney Takashi Okabe

Claims (1)

[Claims] (1) A fuel injector that integrally includes an air amount sensor that detects the amount of air supplied to the internal combustion engine, a pressurizing actuator that pressurizes fuel, and a signal from the air amount sensor. is input, and a control unit that controls a drive signal for the fuel injector so that the integral value of the air amount and the integral value of the drive amount of the fuel injector maintain a predetermined relationship within a predetermined period. A fuel injection device comprising: (21) The fuel injection according to claim 1, wherein the pressurizing actuator is an electrostrictive actuator having an expansion and contraction action, and the driving amount is a driving current when the electrostrictive actuator is expanded. (3) The fuel injection device according to claim 1, wherein the predetermined period is determined by the number of times the fuel injector is driven.