JPS6196161A - Fuel injection controller for diesel engine - Google Patents

Abstract

PURPOSE:To make injection timing and injection rate controllable separately, by installing a solenoid valve which controls pressure in a fuel pressure chamber of a fuel injection pump, while controlling a continuous rating current to the said valve on the basis of each signal out of a running condition detector and a reference position detector. CONSTITUTION:A bosh-form distributor type fuel injection pump 1 applied pressure to fuel drawn in a high pressure chamber 15 by a plunger 11 to be reciprocated and rotated with rotation of a pump driving shaft, and distributes and feeds it to each cylinder via a passage 8b and a delivery valve 16. Tn this case, there is provided with a solenoid valve 2 which opens or closes a spill port 25 being opened to the high pressure chamber 15 and interconnected to the low pressure side via a feedback passage 8c. This solenoid valve 2 is constituted of installing a needle 21 which is moved to the left against a spring 22 with a solenoid coil 23 energized with current. And, energizing to the coil 23 with a continuous rating current is controlled by a controller 3 according to each output of a reference position sensor 4 and a running condition detector 5.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides an i1
This invention relates to a fuel injection control device for a diesel engine that performs one control.

[Prior Art] Conventionally, Japanese Patent Application Publication No. 15B-183826 or
As shown in Japanese Unexamined Patent Publication No. 58-187537, there is an overflow passage whose one end always communicates with the fuel pressurizing chamber of the injection pump and whose other end communicates with the low pressure chamber, and an overflow passage in the middle of this overflow passage. A solenoid valve is provided to open and close the passage. ! ! A device is known that uses a magnetic valve to perform injection at a distance of &13 m. On the other hand, Japanese Unexamined Patent Publication No. 57-86532 describes a device for controlling the injection rate. Based on the above-mentioned two conventional technologies, it is possible to consider a device that simply combines both technologies and controls both the injection presentation and the injection rate, but this system has a complicated and expensive configuration, and the pump is not as efficient. An injection tI4m control device using a solenoid valve overflow type is known in which the injection cam has a special shape and the injection rate can be changed according to the injection timing, but it has the following drawbacks.

B. Injection timing and injection rate cannot be changed independently.

(b) The injection stroke of the pump is a short time, and the solenoid valve must be closed and opened with precise timing to match this short time, so the solenoid valve operates at a very high speed. and a solenoid valve drive circuit are required.

[Problems to be Solved by the Invention] The present invention has been made to solve the above-mentioned drawbacks.SI! By controlling the injection rate and the injection rate with an Ill valve provided in the flow path, a device with a simple configuration and capable of independently controlling the injection timing and the injection rate is provided.

[Means for Solving the Problems] The present invention, which has been made to achieve the above object, has one end that is always in communication with the fuel pressurizing chamber of a fuel injection pump that pumps fuel into an internal combustion engine, and the other end that is always in communication with the fuel pressurizing chamber. an overflow passage C communicating with the low pressure side, an electromagnetic valve for opening the overflow passage C, and an operating condition detector E for detecting various operating conditions of the engine A;
A reference position detector F detects a reference rotational position of the fuel injection pump, and a current value flowing through the electromagnetic valve is controlled in accordance with signals from the reference position detector F and the operating condition detector E. and a control tIl device G, configured to control the injection rate of the fuel injection pump by the magnitude of the current value flowing when the Ti solenoid valve is closed, and to control the injection rate by the opening timing of the solenoid valve. It is characterized by what it did.

[Action 1] In the present invention, the fuel that is pumped to the internal combustion engine A is
1 The pressure in the fuel pressurizing chamber B of the injection pump is controlled by using an electromagnetic valve.Based on the signals from the operating condition detector E and the reference position detector, the control device C The fuel injection rate is controlled by changing the fuel pressure in the pressurizing chamber B depending on the magnitude of the current flowing through the valve valve, and the fuel injection is stopped by opening the solenoid valve, so the fuel injection is controlled by the valve closing timing. Control.

Examples] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, 1 is a Bosch type distribution type diesel engine combustion pump, and this pump 1 includes a pump main body 1A, a solenoid valve 2 that controls this pump main body 1A,
This solenoid valve 2 is controlled based on detection signals from the reference position sensor 4 and the operating condition detector 5! 1'm device 3.

The pump body 1A is a diesel engine IAC (not shown)
As the face cam 12 and roller ring 13 rotate,
and the plunger 11 rotate integrally, and the plunger 11 reciprocates inside the cylinder 7 in the left-right direction in the figure, thereby moving the passage 8a from the fuel tank (not shown) to the height f.
f: Distributing fuel to each cylinder of the engine via the chamber 15, the passage 8b and the delivery valve 16 while feeding it under pressure.

The electromagnetic valve 2 has a solenoid coil 23 and a moving core 24 interposed between the coils 23, a shaft 24a is integrally formed with the moving core 24, and a needle is attached to the shaft 24a. 21 are in contact with each other, and the shaft 24a and the needle 21 are in contact with the matching hole 2.
A and 1A are freely fitted into each other. Further, a stopper 21a for stopping the spring 22 is formed at one end of the needle 21, and the other end is a valve body 21b for opening and closing a spill port 25 serving as an overflow passage communicating with the high pressure chamber 15. In addition, the spill boat 25 is located on the low pressure side l!
Ii) Communicates with the fuel tank via the communication path 8C.

The reference position sensor 4 is composed of, for example, a known electromagnetic pickup, that is, the plunger 11
It consists of a protrusion 4a made of a magnetic material provided at the top, and a detection section 4b provided at a position facing the protrusion 4a. Further, the reference position sensor 4 can detect the reference position of a pump cam (not shown) and also detect the rotation speed from the input period of the signal. When the engine is a four-cylinder engine, the protrusion 4a is provided at every pump rotation angle 90',
It is provided to detect the reference position of injection into each cylinder.

The operating condition detector 5 is comprised of sensors that detect the accelerator position, intake pressure, intake air temperature, and engine coolant temperature.

The control device 3 includes a target injection presentation calculating means 31 that calculates a target injection presentation based on signals from a reference position sensor 4 and an operating condition detector 5, and a target injection presentation calculating means 31 that calculates a target injection presentation based on signals from a reference position sensor 4 and an operating condition detector 5;
a target current calculation means 32 that calculates a target current for determining the injection rate based on the rotational speed signal from the engine; and a target valve opening timing calculation means 32 that calculates the IIA valve opening timing from the target injection rate and the rotational speed. and a drive circuit 34 that causes the target current to flow through the electromagnetic valve 2 when the electromagnetic valve 2 is energized, and cuts off the current of the electromagnetic valve 2 in accordance with the target valve opening timing signal.

Next, the operation of the above configuration will be explained.

Detection signals from the reference position sensor 4 and the operating condition detector 5 are processed by the control device 3 to cause current to flow through the solenoid coil 23 of the solenoid valve 3. As a result, the moving core 24 is pulled to the left in the figure, and the valve body 21b of the needle 21
The spill boat 25 constituting the overflow passage is closed to maintain the pressure in the high pressure chamber 15. In this situation,
When the plunger 11 is moved to the right in the figure by the driving force from the engine and the fuel in the high pressure chamber 15 is compressed, the high pressure chamber 1
The pressure of the fuel in step 5 exceeds the opening pressure of the nozzle (not shown),
The fuel passes through the delivery pulp 16 and is injected from the nozzle. If the current to the solenoid coil 23 is cut off during this injection period, the force that attracts the moving core 24 disappears, and the fuel in the pressure chamber 15 pushes the valve body 21b of the needle 21 to open the spill boat 25. The fuel in the pressure chamber 15 is then transferred to the relatively low pressure fuel in the pump housing.
Returns to the first compartment and reduces its pressure. At that point, fuel injection ends.

The above-mentioned $1ltXl of the fuel injection 9Affi is performed by the control device 3 that controls the amount of energization to the solenoid coil 23, that is, the target valve opening timing calculation means 31, the target amount valve time) I calculation means 33, and the drive circuit 34. This is done by controlling the cutoff timing of the current flowing through the solenoid coil 23 of the electromagnetic valve 2 to arbitrarily control the fuel injection m.

On the other hand, the value of the current flowing through the solenoid coil 23 and the solenoid valve 2
The relationship between the opening pressure of the spill port 25 and the opening pressure of the spill port 25 is as shown in the graph of FIG. That is, as shown in the figure, the current i and the valve opening pressure PO are approximately proportional.

Here, when the current i is zero, the valve opening pressure takes a negative value a because of the spring 22. The spring 22 is set in the valve direction and its action is to ensure that the spill port 25 is open when the current is interrupted.

By changing the current value 1 of the solenoid valve 2 while the pump 1 is injecting fuel, the maximum pressure in the pressure chamber 15 can be set to the valve opening ff:Po of the solenoid valve 2.

Therefore, the injection rate can be changed by changing the current to the solenoid coil 23 using the target current calculating means 32 and the drive circuit 34 of the control device 3 in accordance with the signals from the reference position sensor 4 and the operating condition detector 1 5. I can do it. For example, P is higher than the nozzle opening pressure and is relatively high.
When O is set, the injection rate waveform becomes as shown by the solid line in FIG. 4(A). Furthermore, if PO is set to a value higher than the nozzle opening pressure and relatively low, the injection rate waveform will change as shown in Figure 4 (B
) as shown by the solid line. Therefore, Fig. 4(A)
The waveform is higher than that in FIG. 4(B), that is, the fuel injection rate is set higher. In this way, the injection rate can be changed by the value of the current flowing through the electromagnetic valve 2 during fuel injection.

In addition, the values shown by the solid line in Figure 4 are shown with the timing of the beginning of injection and the end of injection tA being the same in both Figures 4 (A) and (B), but the injection behavior in this case is Figure 4 (A> has more values. Therefore, Figure 4 (A) and Figure 4 (B)
With this control, it is possible to maintain the same injection interval by shifting the injection end timing later, as shown by the broken line in FIG. 4(B).

That is, the fuel injection rate from the fuel pump can be controlled by the magnitude of the current value passed through the solenoid valve 2 when the valve is closed, and the fuel injection rate can be controlled by the opening timing of the solenoid valve 2. In addition,
This fuel injection profile is obtained by correcting the basic injection profile based on water temperature, etc., and this basic injection t14m is determined by the rotational speed, basic injection m, and throttle 17flUcr shown in FIG.
It is set based on the graph obtained from the value of .

Next, a more specific circuit for the control device 3 shown in FIG. 2 will be explained with reference to FIGS. 6 to 10.

In FIG. 6, numeral 35 is a known waveform shaping circuit that shapes the waveform of the reference position sensor 4 into a rectangular wave; for example, the one disclosed in FIG. 6 of Japanese Patent Application Laid-Open No. 57-140530M can be used. 36 is an A/D converter that converts analog signals from the various operating condition detectors 5 into digital values that can be input to the microcomputer 37; for example, MB4053 manufactured by Fujitsu can be used.

37 is a microcomputer that calculates the rotational speed from the time width of the rise or fall of the rectangular wave from the waveform shaping circuit 35, adjusts the reference position from the input time, and also calculates the signal from the operating condition detector 5. A/D converter 36
The target valve opening timing and target current value are calculated and output.

38 is a D/A converter which converts the digital value corresponding to the eye F current value outputted by the microcomputer 37 into an analog value. Specific circuit examples are shown in FIGS. 7 and 8. In Figure 7, the microcomputer 37 converts the digital value to 8.
An example is shown in which pits are output in parallel, and a resistance ladder 381 is used. For example, 16B-102-MBI manufactured by Susumu Industries can be used. FIG. 8 shows another D/A converter 38, in which a microcomputer 87 outputs a digital value as a duty rectangular wave of a certain frequency, using a known active filter. That is, the D/A converter 38 is connected to the power supply Vc.
an inverter 402 connected to the microcomputer 37 via a resistor 401, and an amplifier 403 having one input as the output of the inverter 402;
It is composed of resistors 404 to 406 and capacitors 410 to 412, and converts the output signal from the microcomputer 37 into an analog voltage proportional to the target current value.

Reference numeral 39 in FIG. 6 is a drive circuit, which receives the target valve opening timing signal;
This is a circuit that drives the solenoid valve 2 according to the target current signal. Specific circuits are shown in FIGS. 9 and 10. 9th
In the first circuit shown in the figure, the microcomputer 3
The target current value calculated in step 7 is converted into an analog signal by the D/A converter 38 and sent to the operational amplifier 31 in the drive circuit 39.
2. On the other hand, the actual current value flowing through the solenoid valve 2 is detected by the current detection resistor 315, and is detected by the operational amplifier 3.
13 and input to the operational amplifier 312.

The operational amplifier 312 controls the base current of the power transistor 314 so that the error between the target current value and the actual current value becomes zero. On the other hand, the microcomputer 37 controls the transistor 311 in accordance with the target valve opening timing and target valve closing timing.
and turns on the base current of the power transistor 314.
, OFF, and then the current of the solenoid valve 2 is turned ON and OFF.

That is, for example, the terminal 360 in FIG.
A rectangular wave current according to the target valve opening timing and valve closing timing flows as shown in (a) of the figure, and the transistor 311
On the other hand, the terminal 361 receives the signal (b) in FIG.
Eye F! By applying a voltage corresponding to the current value and inputting it to the operational amplifier 31.2, the first
A current as shown in FIG. 1(C) flows through the solenoid coil 23 of the solenoid valve 2. Note that 316 is a capacitor for preventing oscillation, 351 to 359 are resistors, 370 is a Zener diode, and 380 is a DC power supply.

FIG. 10 shows a second circuit example of the drive circuit 39, in which the p + = lightning current digital value output from the microcomputer 37 is converted into an analog current by the D/A converter 38,
A voltage as shown in FIG. 12(e) is inputted to the operational amplifier 317 as an error amplifier via the terminal 331.

On the other hand, the current flowing through the solenoid valve 2 is detected by a current detection resistor 315, and an operational amplifier 313a as a current signal detection amplifier and an operational amplifier 3 as a current signal amplifier.
13b and is input to the operational amplifier 317. The operational amplifier 317 amplifies the error between the target current value and the actual current value and inputs it to the operational amplifier 319 as a comparator. The operational amplifier 318 is a triangular wave oscillator. The triangular wave generated by the operational amplifier 318 and the error signal are compared by the operational amplifier 319, and a current as shown in FIG. control so that the actual current value matches the actual current value.

On the other hand, the microcomputer 37 drives the transistor 311 with a current as shown in FIG. 12(d) in accordance with the target valve opening timing and target valve closing timing, and turns off the base current of the power transistor 314. Therefore, according to the above-mentioned FIG. 10, the drive circuit 39 (
A current flows to the solenoid valve 2, as in a).

In addition, 320 to 338 in FIG. 10 are resistors, and 340 to 34
2 is a capacitor.

Next, the operation of the above structure will be explained with reference to the flowcharts shown in FIGS. 13 to 16 and the graphs shown in FIGS. 17 to 19.

The microcomputer 37 shown in FIG.
The series of processing shown in the main routine of FIG. 13 is repeatedly performed based on the program in the main routine.

First, in step 101, it is determined whether or not the key switch is turned on based on the input signal from the key switch included in the operating condition detector 5. If the determination result is YES, in step 102, the microcomputer 37
Initialize. Then, in step 103, it is determined whether or not the engine is in the starter position based on the input signal from the key switch.

If the determination result is YES, various input signals other than the key switch from the operating condition detector 5 are taken in at step 104. Then, in step 105, a basic injection map (governor pattern) as shown in FIG. 5 in the ROM is searched. Here, this pattern search is performed based on the rotational speed N taken in by the reference position signal interruption described later and the accelerator operation amount α taken in the step 104, and the corresponding basic injection presentation Qp
(N, α) data is calculated within the microcomputer 37.

Next, in step 106, u
Processing is performed to correct the main injection ff1Qp (N, α) and calculate the corrected base injection gAffiQAp (N, α).

That is, based on the intake pressure information from the intake pressure sensor, the intake temperature information from the intake air temperature sensor, and the cooling water temperature information from the cooling water temperature sensor, which are taken in from the operating condition detector 5 in step 104, the basic Injection filQp
Correct (N, α) and correct basic ll11 projection QAp
Calculate (N, α).

In step 107, the microcomputer built-in ROM
A two-dimensional map as shown in FIG. 17 is searched.

The pattern search here is performed based on the rotation r&N and the corrected base injection QAffiQAp obtained in step 106, and the corresponding target valve opening timing Qt (N
, QAp) data is computed.

Next, in step 108, the time Tc (FIG. 19) for closing the spill boat 25 of the injection pump 1 is calculated. This is a preparation in which the solenoid valve 2 is closed in advance so that when the next pumping process of the plunger 11 starts, fuel will be pumped from the high pressure chamber 15, and the duration of the suction process of the plunger 11 will be Then anytime is fine.

That is, this time Tc is proportional to the reciprocal of the pump rotation speed Np, and for example, a map as shown in FIG. 19,
Or it type 5 [for example, T for a 4-cylinder distribution pump
c-(60/8xNp) seconds]. Next, in step 109, the target current value is is calculated. This is determined by searching a two-dimensional map in the ROM, as shown in FIG. 18, in which the rotational speed N and the injection ff1QAp are used as parameters.

Next, in step 110 of FIG. 13, it is determined whether or not the key switch is turned off. If the determination result is NO, step 104 is executed again, and thereafter step 1
Step 104 until the determination result of step 10 is reversed to YES.
, 105, 106° 107, 108, and 109 are executed repeatedly.

While repeating the above arithmetic processing, a reference position signal pulse is input, and when the microcomputer 37 detects the rising edge of the pulse, the program moves to the reference position interrupt routine shown in FIG. 14. In the reference position interrupt routine, first, in step 210, the current timer counter value in the microcomputer 37 is read. Next, in step 211, the timer counter value and the target injection period Qt obtained in step 107 are added.

In step 212, the added value is set as the electromagnetic valve drive output interrupt time that becomes the injection path. moreover,
At step 213, the number of revolutions N is calculated from the difference between the counter value at step 210 and the counter value at the previous reference position interrupt. The program then returns to the main routine and resumes normal operations.

Also, when the value of the timer counter matches the solenoid valve opening drive output interrupt time in step 212.

The process moves to the injection path output interrupt routine shown in FIG. 15, and in step 220, a solenoid valve opening drive signal output is generated, a signal to interrupt the energization of the solenoid valve 2 is generated, the energization of the solenoid valve 2 is interrupted, and the nozzle fuel injection ends. Next, in step 221, the overflow port closing time TC is increased to the value of the timer counter when the reference position signal was input. Further, in step 222, the result obtained in step 221 is set as the electromagnetic valve closing drive interrupt time. Next step 223
outputs the target current is to the D/A converter 38, and outputs the target current is to the D/A converter 38,
I am able to shoot. Then, return to the main routine again.

Furthermore, when the value of the timer counter matches the solenoid valve closing drive output interrupt time in step 222, the process moves to the spill port close output interrupt routine shown in FIG. 16, and in step 230, a solenoid valve opening drive signal is output. Then, by closing the spill port 25, the next pumping (fuel injection) can be started. Then, return to the main routine again. after that,
Once the key switch is turned off, step 11
1, the high pressure chamber 15 shown in FIG.
A solenoid valve opening drive signal is output so that the low pressure chamber and the low pressure chamber are always in communication (the energization of the solenoid valve 2 is stopped).

An example of how to obtain the maps shown in FIGS. 17 and 18 described above is as follows. First, the target current 11iis corresponding to the required injection rate is determined for each combination of rotational speed and injection rate according to each operating state of the engine, and a map as shown in FIG. 18 is created. Next, the current is controlled in accordance with the obtained map in FIG. 17, and a target valve opening timing Qt for achieving a predetermined injection pattern is determined, and a map as shown in FIG. 17 is created.

The values of the map in Fig. 17 and the map in Fig. 18 have a one-to-one correspondence, so when the map value of the target current value is changed, the value of the corresponding grid point of the target valve opening timing always changes. Be changed.

In the above embodiment, the fuel injection timing is controlled by other known means, and can be controlled independently of the injection presentation and injection rate. It is also possible to apply a known electronic υ control injection timing control device and have the microcomputer in the device of the present invention perform calculations for injection timing control in a time-sharing manner.

Therefore, according to the above configuration, the injection rate can be controlled by the current value flowing through the solenoid valve 2, and the injection presentation can be controlled by the opening timing of the solenoid valve 2, so that it is not necessary to use a cam with a complicated shape as in the past. Therefore, the structure becomes simpler.

Furthermore, in the present invention, it is only necessary to open the solenoid valve at a good timing of v3 degrees during the injection stroke of the pump, and the valve can be closed at a time other than during the injection stroke, such as the pump suction stroke. This eliminates the need for high-speed solenoid valves.

[Effects of the Invention] As described above, in the present invention, in a diesel fuel injection device, the injection rate is controlled by the current value flowing through the solenoid valve, and the injection amount is controlled by the timing when the solenoid valve is opened. The injection presentation and injection rate can be controlled with a simple structure, and the I'l at the time of injection can be controlled.
This has the advantage that l and the injection rate can be set independently.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a schematic block diagram showing an embodiment of the invention, Fig. 3 is a characteristic diagram of the embodiment, and Fig. 4 shows the operation of the embodiment. Explanatory diagram to explain, fifth
The figure is a characteristic diagram of the same embodiment, Figures 6 to 10 are circuit diagrams showing the specific configuration of the same embodiment, and Figures 11 and 12 are
The figure is a time chart explaining the operation of the same embodiment, No. 13.
16 through 16 are flowcharts for explaining the operation of the embodiment, and FIGS. 17 through 19 are characteristic diagrams of the embodiment. A...Internal combustion engine B...Fuel pressurization chamber C...
Overflow passage D...Solenoid valve E...Operating condition detector F...Reference position detector G...Control device

Claims (1)

[Scope of Claims] 1. An overflow passage whose one end always communicates with a fuel pressurizing chamber of a fuel injection pump that pumps fuel to an internal combustion engine and whose other end communicates with a low pressure side, and which opens and closes this overflow passage. an electromagnetic valve; an operating condition detector that detects various operating conditions of the engine; a reference position detector that detects a reference rotational position of the fuel injection pump; and from the reference position detector and the operating condition detector. a control device that controls a value of current flowing through the solenoid valve in accordance with a signal from the solenoid valve, and controls an injection rate of the fuel injection pump depending on the magnitude of the current value that flows when the solenoid valve is closed; A fuel injection control device for a diesel engine characterized by controlling injection characteristics by valve timing. 2. The fuel injection control device for a diesel engine according to claim 1, wherein the solenoid valve is configured to open the valve when a current flowing through the solenoid valve is cut off. .