JPH0134290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel control device for an internal combustion engine in which fuel injection into the engine is controlled by a solenoid valve.
More specifically, it relates to a structure for regulating the amount of fuel injected.

In recent years, efforts have been made to improve fuel efficiency in internal combustion engines, such as marine diesel engines, from the viewpoint of improving fuel efficiency and preventing inferior fuel oil. In other words, in addition to accurate control of the fuel injection amount, it is possible to control the optimal fuel injection timing according to the operating condition of the internal combustion engine, improve fuel efficiency by increasing the injection pressure, and avoid using inferior fuel oil. Efforts are being made to make this possible.

Typical prior art is, for example, Japanese Patent Publication No. 52-11333 and Japanese Patent Publication No. 56-
This is a fuel injection device for internal combustion engines known as 143342 and others. 1000Kg/ ^cm2 by fuel pump
The fuel oil, which has been pressurized to a near level, is guided to one pressure accumulator,
High pressure fuel oil is supplied from this pressure accumulator to the fuel valve of each cylinder. On the other hand, the fuel valve is opened and closed by a solenoid valve powered by hydraulic pressure. In this way, the drive timing and drive time of the solenoid valve are controlled by the electronic control circuit in synchronization with the movement of the internal combustion engine, making it possible to control the optimum fuel injection timing and accurate fuel injection amount.

In such prior art, since high-pressure fuel oil is commonly supplied to each fuel valve from one pressure accumulator, a problem arises in that the load sharing among the cylinders becomes unbalanced. This is because due to subtle dimensional differences in fuel valves during manufacture and changes over time, differences in fluid resistance of fuel valves occur, and even if the fuel valve opening time is the same, the amount of fuel injected to each cylinder may vary. This is because they are different from each other.

In order to prevent such an imbalance in load sharing between cylinders, the following measures (a) and (b) can be considered simply.

(a) In order to adjust the fuel pressure for each cylinder, a pressure accumulator shall be provided individually for each cylinder. Fuel is supplied from each pressure accumulator to the internal combustion engine via a solenoid valve for each cylinder. According to such measures, each pressure accumulator that holds high-pressure fuel oil is expensive, leading to a significant increase in the manufacturing cost of the internal combustion engine.

(b) When fuel is supplied from one pressure accumulator to each cylinder via the solenoid valve for each cylinder, the driving time of the solenoid valve is individually and independently controlled. According to this measure, the configuration becomes complicated, which increases costs and reduces reliability.

The present invention eliminates these problems, balances the load between cylinders under one pressure accumulator, has a relatively simple configuration, is excellent in cost reduction, and is a highly reliable internal combustion engine. An object of the present invention is to provide a fuel control device for an engine.

In the present invention, the fuel from the pressure accumulator 3 is supplied to the solenoid valve 6a.
6c to fuel valves 8a to 8c individually provided for each cylinder, and means for setting a common driving time Tinj corresponding to a common fuel injection amount for each cylinder. , means provided corresponding to each cylinder and generating an electric signal representing the amount of correction of the common drive time Tinj;
34a to 34c, crank angle detecting means 12, 16, 17, and a signal responsive to the output of the crank angle detecting means 12, 16, 17 and representing the fuel injection timing αi by the solenoid valves 6a to 6c for each cylinder. Means for deriving 37, 47, 38a~
38c, an oscillator 32 with a variable oscillation period for deriving a clock signal having an oscillation period corresponding to the electric signal in response to the electric signals from the electric signal generating means 34a to 34c, and a fuel injection timing deriving means 37. In response to the signal representing the fuel injection timing αi from 47, 38a to 38c, the common drive time Tinj from the common drive time setting means is set by the oscillator 32 using the electric signal corresponding to the cylinder corresponding to the fuel injection time αi. The solenoid valve 6 for the cylinder corresponding to the fuel injection timing αi is counted based on the clock signal from the fuel injection timing αi.
Means for opening a to 6c 25a to 25c, 27a to 27c, 29,
31. A fuel control device for an internal combustion engine, characterized in that it includes:

In the present invention, electric signal generating means such as a variable resistor is provided corresponding to one or more cylinders. The electric signal generating means derives electric signals each representing a correction amount of the driving time corresponding to a fuel injection amount common to each corresponding cylinder. An oscillator responsive to the electrical signal from the electrical signal generating means derives a pulse having an oscillation period corresponding to that cylinder. The arithmetic device implemented by a microcomputer or the like calculates the common driving time of the electromagnetic valves as described above based on the operating state of the internal combustion engine, such as the number of rotations of the crank angle and the pressure of the combustion chamber. The counter counts the pulses from the oscillator and clocks the drive time set value calculated by the arithmetic unit.
In this way, the drive time of the solenoid valve common to each cylinder is modified and determined for each cylinder. In this way, the drive time common to the solenoid valves, and therefore the fuel injection amount common to each cylinder, is adjusted for each cylinder by the electrical signal from the electrical signal generating means, which reduces the load between the cylinders. Accurate balance can be achieved with a relatively simple configuration. Moreover, since the structure is relatively simple, it is excellent in reducing cost and improving reliability.

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows the overall configuration of an embodiment of the present invention. An internal combustion engine, such as a marine diesel engine, has one or more cylinders, which are designated by reference numerals 40a-40c. Although FIG. 1 shows the case of an internal combustion engine with three cylinders, there is no problem with an internal combustion engine with four or more cylinders or less than three cylinders. Fuel is injected and supplied from fuel valves 8a to 8c to the combustion chambers of each cylinder 40a to 40c. The fuel valve 8a is a needle valve 42 biased by a spring 41.
The fuel supplied to the pressure accumulation chamber 43 is supplied to the nozzle 4.
4 into the combustion chamber 48. Remaining fuel valve 8
a and 8c also have similar configurations.

The fuel oil in the fuel tank 1 is pressurized by the fuel pump 2 and guided to the pressure accumulator 3. Although only two fuel pumps 2 are shown in FIG. 1, there may be one, three or more fuel pumps depending on the configuration of the internal combustion engine and the number of cylinders. The pressure regulating valve 4 functions to keep the fuel pressure in the pressure accumulator 3 constant. Pressure accumulator 3
The fuel is supplied to fuel valves 8a to 8c via electromagnetic valves 6a to 6c. In the following description, the subscripts a to c may be omitted to collectively represent the constituent elements. In the state shown in the first diagram in which the solenoid valve 6 is not energized, the high pressure fuel oil in the pressure accumulator 3 is shut off by the solenoid valve 6 and is not supplied to the fuel valve 8. When the electromagnetic valve 6 is energized, the injection pipes 5 and 7 are brought into communication and the high pressure fuel oil in the pressure accumulator 3 is injected from the fuel valve 8 into the combustion chamber 48 of the cylinder 40. Although the illustrated solenoid valve 6 directly opens and closes the flow path of high-pressure fuel oil, in other embodiments, a solenoid valve that doubles the electromagnetic force with hydraulic pressure may be used.

The control device 10 controls the electromagnetic valve 6 and also controls the starting valve 14 when starting the internal combustion engine. The control device 10 compares the signal from the rotation speed setting device 11 and the signal from the rotation speed detector 13,
Based on this, the driving time of the solenoid valve 6, that is, the pulse width of the electric signal that excites the solenoid valve 6, is adjusted to control the fuel injection amount and the rotation speed of the internal combustion engine. Resolver 12 is coupled in relation to the crankshaft of the internal combustion engine and derives an analog signal representative of the crank angle. The control device 10 receives the signal from the resolver 12 and sends out an electric signal to excite the solenoid valve 6 at an optimal timing. The fuel controller 15 defines the maximum amount of fuel to be injected into each cylinder at a time, and plays a role equivalent to a torque limiter. The output from the pressure detector 9 that detects the pressure of fuel oil in the pressure accumulator 3 is used to calculate the fuel injection amount.

FIG. 2 shows a specific configuration of the control device 10. As shown in FIG. For ease of understanding, parts corresponding to those in FIG. 1 are given the same reference numerals. Regarding the resolver 12, one of the plurality of cylinders of the internal combustion engine is set as a reference cylinder, and the resolver 12 is set so that the crank angle detected by the resolver 12 becomes zero at the top dead center position of this reference cylinder. installed on. To simplify the explanation, the reference cylinder will be described below, but for cylinders other than the reference cylinder, the difference in installed crank angle from the reference cylinder may be taken into consideration.

The analog signal representing the crank angle from the resolver 12 is R/D (Resolver to Digital, abbreviated as R/D).
D) Converted by a converter 16 into a 10-bit digital angle signal 18 representing the crank angle. Therefore, the fuel injection timing can be specified with a resolution of 360°/2 ¹⁰ = 0.35°. Each bit of the R/D converter 16 has a weight of 360/2 ⁿ (n=0, 1, 2, . . . , 9). In order to make the fuel injection timing indication highly accurate, the number of bits of the angle signal 18 may be increased, and if coarseness is acceptable, the number of bits may be reduced.
For example, the R/D converter 16 is manufactured by Data Device Composition (commonly known as DDC).
An RDC-632 can be used, and since this device has a 12-bit output, the upper 10 bits will be used in this embodiment. The rotation detection circuit 17 receives the angle signal 18 as an input, detects the top dead center of the reference cylinder, and outputs an interrupt signal to a line 19, which will be used in the description of the operation described later. This rotation detection circuit 17 can be easily realized, for example, by configuring a differential circuit to detect the fall of the most significant bit of the angle signal 18. Note that this rotation detection circuit 17 does not necessarily have to detect the top dead center of the reference cylinder, and only once per cycle of the internal combustion engine.
It is only necessary to output an interrupt signal to line 19 at a predetermined crank angle.

Arithmetic device 37 forming the central part of fuel control device 10
is realized, for example, by a microcomputer. The arithmetic unit 37 normally executes a main arithmetic routine as shown in FIG. 3 in accordance with a program stored in a read-only memory (ROM) 47. That is, when the power is turned on, the arithmetic unit 37 resets internal registers (shown) and flags (not shown) in step 301, and performs necessary initialization processing. Step 3
In 02, the rotation speed setting device 11 and the fuel limiter 1
Read the value from 5. In step 303, output signals from the rotational speed detector 13 and pressure detector 9 are read to determine the operating state of the internal combustion engine. In step 303, output signals from a thermometer for detecting the temperature of cooling water for the internal combustion engine, an oxygen concentration meter for exhaust gas control, or the like may be read. Rotation speed detector 13
The R/D converter 16 can be attached to the main shaft or crankshaft and generate a voltage proportional to its rotation speed, but the value of the R/D converter 16 can be changed by
If the number of revolutions is calculated by reading the number of times, the number of revolutions detector 13 can be omitted.

In step 304, steps 302 and 303
Calculate the fuel injection time Tinj using the value read in. As a calculation method, the following procedure can be considered, for example.

E ⁽ⁿ⁾ =SV ⁽ⁿ⁾ −PV ⁽ⁿ⁾ …(1) ΔTinj ⁽ⁿ⁾ =Kp・{E ^(n-1) −E ⁽ⁿ⁾ }+KI・E ⁽ⁿ⁾ …(2) T1 ^{( n)} =Tinj ^(n-1) +ΔTinj ⁽ⁿ⁾ …(3) Tinj ⁽ⁿ⁾ = min (T1 ⁽ⁿ⁾ , T2 ⁽ⁿ⁾ ) ...(5) where SV: rotation speed setting value PV: rotation speed detection value EV: fuel limit value P: (fuel) pressure detection value Kp, KI , Ke: constant Here (n) is the number of calculation loops,
The (n)th Tinj ⁽ⁿ⁾ is calculated from the (n-1)th calculated value and the (n)th read value.

In step 305, the fuel injection timing αi (i=1
~z, where z is the number of cylinders). i.e.
αi is determined by referring to the data table stored in the read-only memory 47 using PV ⁽ⁿ⁾ and Tinj ⁽ⁿ⁾ as parameters. In this way, the arithmetic unit 37 performs steps 302→303 in FIG.
A loop of →304→305→302→... is constantly executed.

When the crankshaft reaches the top dead center position, the rotation detection circuit 17 sends an interrupt signal to the arithmetic unit 37 on the line 19.
, the arithmetic unit 37 temporarily suspends the processing illustrated in FIG. 3 and executes the interrupt routine illustrated in FIG. 4. In FIG. 4, it is determined in step 401 whether or not the engine is started, and if the engine is started, a starting valve control routine 404 is executed. Note that since the control of the starter valve 14 is outside the scope of the present invention, a detailed explanation will be omitted. If the engine is not started, the process proceeds to step 402, where the optimum injection timing αi obtained in step 305 is output to the timing register 22 shown in FIG. 2 via the data bus 20. For cylinders other than the standard cylinder, αi is set by the installation angle difference from the standard cylinder.
and sets the value in the timing register corresponding to that cylinder. Next, in step 403, the fuel injection time Tinj calculated in step 304 of FIG.
9 is output. After step 403 is completed, the arithmetic unit 37 resumes execution of the main arithmetic routine of FIG. 3 from the point where it was interrupted.

Referring again to FIG. 2, timing register 2
2 is composed of a part of a parallel input/output LSI 38 such as 8255 manufactured by Intel Corporation in the United States, and the fuel injection timing αi is input to a 10-bit timing register 22 in two parts via an 8-bit data bus 20. written. That is, the upper 8 bits are written first, and then the lower 2 bits are written. Data on data bus 20 is latched into timing register 22 in synchronization with a selection signal derived from arithmetic unit 37 on line 21.

The timing signal on line 23 representing the 10-bit optimum injection timing αi latched in timing register 22 is connected to one input terminal of comparator 24, and the other input terminal of comparator 24 is connected to the 10-bit angle signal A signal 18 is provided, and the magnitude relationship between the two signals is constantly compared. Here, as the comparator 24, for example, a comparator made by Texas Instruments, Inc.
SN74LS682 is suitable. When the magnitudes of the angle signal 18 and the timing signal of the line 23 match, a signal indicating the match is output from the output terminal = of the comparator 24. This signal indicating a match can be used, for example, to
A flip-flop 25 made up of a portion of the SN74LS279 is set and outputs an injection pulse signal on line 26. This injection pulse signal is given to the drive circuits 27a to 27c, thereby exciting the solenoid 28 of the electromagnetic valve 6, thereby starting injection.

The timing register 22, the comparator 24, the flip-flop 25, and the drive circuit 27 are provided in the number of solenoid valves according to the number of cylinders of the internal combustion engine, and are controlled by one arithmetic unit 37.

The speed regulating register 29 is composed of, for example, SN74LS374 manufactured by Texas Instruments, USA.
The arithmetic unit 37 sets the fuel injection time Tinj. In this embodiment, the speed regulating register 29 consists of 8 bits, and when specifying the fuel injection time in units of 0.1 ms, it is possible to specify up to 25.5 ms. Note that by increasing the unit time, you can increase the maximum time that can be specified, and by increasing the number of bits in the speed regulating register 29, you can decrease the unit time accordingly or increase the maximum time that can be specified. You can also.

The governor signal from line 30, which is set in governor register 29, is synchronized with the output signal on line 50 from OR gate 36, which receives the injection pulse signals from all lines 26a-26c, for example to the US RCA. The number is placed in a down counter 31 made of CD40103B manufactured by Co., Ltd. A clock signal from an oscillator 32 is connected to the CLK terminal of the down counter 31 via a line 49, so that it can count down. That is, each time a clock signal comes in from the oscillator 32, the contents of the down counter 31 decreases its value, and when a clock signal corresponding to the initially set value comes in, the contents of the down counter 31 become zero. Then,
A count up signal is output to line 45 from the CO terminal. As a result, the flip-flop 25 is reset and the injection pulse signal on the line 26 is stopped, so that the electric signal that was energizing the solenoid of the electromagnetic valve 6 via the drive circuit 27 is stopped, and fuel injection is terminated.

The oscillator 32 is, for example, manufactured by Intersil Corporation in the United States.
555 is used as an oscillator with a variable oscillation period, and the oscillation period can be adjusted by changing the voltage applied to the terminal CTR of the oscillator 32 using the period adjustment device 33. Specifically, the voltage set by the variable resistor 34 as an electric signal generating means is controlled by the injection pulse signal on the line 26 to a multiplexer or an electronic switch 35 constructed of CD4016B manufactured by RCA, USA, for example.
is selectively applied to the CTR terminal of the oscillator 32 via the oscillator 32, and has an oscillation period corresponding to the voltage of the oscillator 32. Therefore, by adjusting the variable resistor 34, the oscillation period of the oscillator 32 is changed, and the count-up time of the down counter 31 is changed. The operating time, that is, the fuel injection time, can be adjusted.

Based on the time chart shown in Figure 5,
The timing operation of the injection pulse signal on the line 26 during the operation of the fuel control device shown in the second figure will be explained. For convenience of explanation, time charts for three cylinders are shown in FIG. 5 as in FIG. 1. Fig. 5 a1, Fig. 5 a2 and Fig. 5 a3 are the comparator 2.
These are the respective outputs (=) of 4a to 24c. When the timing signal on the line 23 and the angle signal 18 match in magnitude, it becomes "L". Here "L" is
This is an abbreviation meaning that the signal is low level, and high level is abbreviated as "H". Comparator 24 shown in FIG. 5 a1, FIG. 5 a2 and FIG. 5 a3
When the outputs of a to 24c become "L", flip-flops 25a to 25c are set.
The outputs of the flip-flops 25a to 25c are the fifth
It is shown in FIG. b1, FIG. 5 b2 and FIG. 5 b3. By setting the flip-flops 25a to 25c, their set outputs become "H".
becomes. FIG. 5d shows the output from the OR gate 36, which generates the conditions for placing the regulating signal on the line 30 in the down counter 31. That is, lines 26a-2
When all the injection pulses controlling fuel injection 6c are at rest, the output of the OR gate 36 shown in FIG. The clock signal from the oscillator 32 is sent to the down counter 31.
does not affect the content. The waveform of the clock signal from oscillator 32 is as shown in FIG. 5e.

When any of the outputs of the flip-flops 25a to 25c becomes "H", the OR gate 3
6 becomes "H", and from this moment the down counter 31 starts counting, and the setting of a number from the speed control signal on the line 30 is prohibited. Among the outputs from flip-flops 25a to 25c,
By the signal becoming "H", the electronic switch 35
A corresponding one of the contacts is made conductive, thereby applying the voltage of the corresponding variable resistor 34a to 34c to the oscillator 32. Oscillator 32 derives a clock signal having an oscillation period corresponding to the voltage. The down counter 31 counts down this clock signal, and when the content reaches zero,
A count-up signal is derived on line 45 to reset flip-flop 25. The count up signal derived from the down counter 31 on line 45 is as shown in FIG. 5c. This count-up signal resets the flip-flops 25a-25c, so the signals that were "H" on lines 26a-26c are reset to "L".

In this time chart of Figure 5, line 30
It is shown how the pulse widths of the injection pulse signals on the lines 26a to 26c change for the same speed control signal. That is, FIG. 5 b1 shows a signal with a standard pulse width, FIG. 5 b2 shows a signal with a large pulse width when the oscillation period of the oscillator 32 becomes longer, and FIG. A signal is shown having a pulse width reduced by shortening. In this way, the optimum fuel injection amount is supplied to each cylinder.

Although the variable resistor 34 was used to adjust the period of the oscillator 32 as described in connection with FIG. A configuration may also be adopted in which a detection means is provided and the period of the oscillator 32 is automatically adjusted according to the output of the load detection means. To be more specific, the load detection means includes a finger pressure gauge that detects the pressure in the combustion chamber in each cylinder, or a cooling water temperature gauge installed in the cooling water passage of each cylinder.
Alternatively, an exhaust gas temperature meter or the like for each cylinder can be used, and the outputs from these load detection means are read into the arithmetic unit 37 via an analog/digital converter, and the oscillator 32 is used so that the load state of each cylinder is balanced. The voltage value at the terminal CTR is controlled. In this case, the variable resistors 34a to 34c of the synchronization adjustment device 33 in FIG. 2 are replaced by the digital/analog converters 46a to 46 as shown in FIG.
6c, and the digital signal from the arithmetic unit 37 is sent to the digital/analog converters 46a to 46.
c is converted into a voltage and applied to the oscillator 32 from the electronic switch 35.

The invention can be widely implemented in connection with internal combustion engines.

In the embodiment shown in FIG. 2, even if the synchronization adjustment device 33 is not adopted and the oscillator 32 sends out a pulse signal with a constant period, the fuel injection time Tinj set in the speed regulating register 29 can be changed for each time. Although the same effect as the present invention can be expected even if the change is made for each cylinder, such a system not only makes the program stored in the ROM 47 of the microcomputer complicated, but also increases the program development cost. As the engine speed increases, the third
The execution speed of the programs shown in FIGS. and 4 is lower than the engine speed, which has the disadvantage that it is not possible to calculate and set Tinj for each cylinder.

As described above, according to the present invention, fuel from the pressure accumulator 3 is supplied to the fuel valves 8a to 8c of each cylinder through the solenoid valve 6.
A common driving time for the solenoid valves 6a to 6c corresponding to a common fuel injection amount to each of the plurality of cylinders
Tinj is determined, and with respect to load imbalance for each cylinder due to wear and tear of the fuel valve of each cylinder, an electric signal representing a correction amount of the common drive time Tinj is generated by the generating means 34a to 34c. Then, the oscillation period of the oscillator 32 is changed according to the electric signal, and the clock signals from the oscillator 32 are counted to open the solenoid valves 6a to 6c for a counting time corresponding to the common drive time Tinj. , can supply the optimal fuel injection amount to each cylinder,
Therefore, it is possible to balance the loads among the cylinders. In addition, the structure is relatively simple, reduces cost, and improves reliability.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram of an embodiment of the present invention, FIG. 2 is a block diagram showing a specific configuration of the control device 10 shown in FIG. 1, and FIGS. 3 and 4 are arithmetic units. 37, FIG. 5 is a time chart for explaining the operations shown in FIGS. 1 and 2, and FIG. 6 is a part of another embodiment of the present invention. It is a block diagram. 3...Pressure accumulator, 6a-6c...Solenoid valve, 8a-8c
...Fuel valve, 10...Control device, 11...Rotation speed setting device, 12...Resolver, 13...Rotation speed detector, 16
...R/D converter, 17... Rotation detection circuit, 22a~
22c...timing register, 24a to 24c...
Comparators, 25a to 25c...Flip-flop, 2
7... Drive circuit, 29... Speed governor register, 31... Down counter, 32... Oscillator, 33... Synchronization adjustment device, 34a to 34c... Variable resistor, 35... Electronic switch, 37... Arithmetic device.

Claims (1)

[Scope of Claims] 1. Fuel from the pressure accumulator 3 is supplied to fuel valves 8a to 8c individually provided for each cylinder via electromagnetic valves 6a to 6c, means for setting a common driving time Tinj corresponding to a common fuel injection amount; and means provided for each cylinder and generating an electric signal representing a correction amount of the common driving time Tinj.
34a to 34c, crank angle detecting means 12, 16, 17, and a signal responsive to the output of the crank angle detecting means 12, 16, 17 and representing the fuel injection timing αi by the solenoid valves 6a to 6c for each cylinder. Means for deriving 37, 47, 38a~
38c, an oscillator 32 with a variable oscillation period for deriving a clock signal having an oscillation period corresponding to the electric signal in response to the electric signals from the electric signal generating means 34a to 34c, and a fuel injection timing deriving means 37. In response to the signal representing the fuel injection timing αi from 47, 38a to 38c, the common drive time Tinj from the common drive time setting means is set by the oscillator 32 using the electric signal corresponding to the cylinder corresponding to the fuel injection time αi. The solenoid valve 6 for the cylinder corresponding to the fuel injection timing αi is counted based on the clock signal from the fuel injection timing αi.
Means for opening a to 6c 25a to 25c, 27a to 27c, 29,
31. A fuel control device for an internal combustion engine, comprising: