JPH0536626B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection amount control device for a diesel engine.

Generally, in a diesel engine, the fuel injection amount is basically calculated based on the engine rotation speed and accelerator opening (engine load). The upper limit value is set accordingly.

However, in the conventional type described above, a filter (integrator circuit) with a time constant of about 100 to 150 msec is usually installed in the input circuit of the intake pressure sensor to reduce the influence of intake pulsation, so there is a delay in intake pressure detection. exists. As a result, the calculated injection amount when the intake pressure suddenly drops during acceleration becomes smaller than the allowable injection amount due to the occurrence of smoke, etc., resulting in poor acceleration.On the other hand, when the intake pressure suddenly drops during deceleration, the calculated injection amount There was a problem that the amount became large and caused the generation of black smoke.

In view of the above-mentioned problems with the conventional type, an object of the present invention is to correct the upper limit value of the basic injection amount when the intake pressure suddenly changes, thereby improving acceleration performance during acceleration and preventing excessive injection amount during deceleration. The purpose is to reduce the amount of black smoke and prevent the generation of black smoke.

FIG. 1 is an overall block diagram for explaining the configuration of the present invention. The basic injection amount calculation means calculates the basic injection amount according to the rotational speed Ne of the diesel engine and the accelerator opening degree Accp. The basic injection amount upper limit calculation means calculates the upper limit value of the basic injection amount according to the engine rotational speed Ne and the intake pressure P of the engine intake passage.
Calculate Q _FULL , and then calculate the upper limit of this basic injection amount.
Q _FULL is corrected by the basic injection amount upper limit value correction means. That is, the intake pressure change detection means detects the intake pressure change rate ΔP per unit time, and the basic injection amount upper limit value correction means detects the intake pressure change rate ΔP based on the magnitude of change in the positive or negative direction. corrects the upper limit value of the basic injection amount. The injection amount calculation means compares the corrected basic injection amount upper limit value Q _FULL ' with the basic injection amount Q _B from the basic injection amount calculation means and calculates the injection amount according to the comparison result. In other words,
If Q _FULL ′≧Q _B , the injection amount Q _FIN is set to Q _B , and Q _FULL
If <Q _B , the injection amount Q _FIN is set to Q _FULL ', and fuel corresponding to that amount is supplied to the diesel engine.

Embodiments of the present invention will be described with reference to the drawings from FIG. 2 onwards.

FIG. 2 is an overall schematic diagram showing an embodiment of a fuel injection amount control device for a diesel engine according to the present invention. In FIG. 2, 10 is an engine main body, 20 is a distribution type (VE type) fuel injection pump, and 30 is a control circuit for controlling the engine main body 10 and the fuel injection pump 20. This is called a control unit (ECU).

The intake manifold 102 of the engine body 10 includes an intake pressure sensor 1 for detecting the absolute pressure of intake air.
04 is provided, and this intake pressure sensor 104 generates an analog voltage signal according to the absolute pressure. Furthermore, a fuel injection valve 106 is provided in the fuel chamber of the engine body 10 for each cylinder to supply pressurized fuel from the fuel injection pump 20 to the intake port.

A centrifugal (vane type) feed pump 202 is coupled to the engine drive shaft 204 and pumps a certain amount of fuel per revolution to a fuel tank (not shown).
It is something that absorbs more. This feed pump 2
02 fuel pressure is regulated by the pressure regulating valve 206, and as a result, the fuel pressure sent into the pump chamber through the hole at the top of the feed pump cover 208 increases in proportion to the pump rotation speed. do. In addition, the feed pump 202
The cross-sectional view on the left side is a 90° development view.

The drive shaft 204 is the feed pump 20
2, the cam plate 210 and the pump plunger 212 are simultaneously driven. A plunger spring 214 urges the pump plunger 212 and cam plate 210 against a fixed roller 216. When the cam plate 210 rotates and its face cam rides on the roller 216, the pump plunger 212 reciprocates a prescribed amount. At the same time, the pump plunger 212 is also performing rotational movement, so it sucks in fuel and distributes it under pressure. The pumping of fuel begins with the pump plunger 212 starting to rise, resulting in it being supplied to the injection valve 106 through the distribution passage 218 and the delivery valve 220, and the pumping of fuel begins with the pump plunger 212 rising further to the spill port 222. The process ends when the right end surface of the spill ring 224 is opened into the pump chamber.

The fuel injection amount is controlled by moving the plunger 228 by controlling the energization duty ratio of the spill control solenoid (linear solenoid) 226, thereby moving the position of the spill ring 222. At this time, the position of the spill ring 222 is detected by the spill position sensor 230 and is controlled more accurately by the control circuit 30.

Further, the gear 232 fixed to the drive shaft 204 is provided with a rotation sensor 234 constituted by an electromagnetic pickup. Generates a pulse signal.

Furthermore, in FIG. 2, 31 is an accelerator pedal, and 32 is an accelerator opening sensor, which generates an analog voltage signal in accordance with the opening degree of the accelerator pedal 31.

FIG. 3 is a detailed block diagram of control circuit 30 of FIG. 2. In FIG. 3, each analog signal of the accelerator opening sensor 32 and the intake pressure sensor 104 is supplied to an A/D converter 302 that has a built-in analog multiplexer, and each analog signal is sequentially A/D converted. Become. Rotation angle sensor 23
The No. 4 pulse signal is supplied to a predetermined position of the input/output port 306 via the rotational speed forming circuit 304.
In this case, the rotational speed forming circuit 3304 generates a binary signal that is inversely proportional to the rotational speed.

A/D converter 302 and input/output port 306
is the CPU 312 and RAM 3 via the common bus 310.
14, ROM316, and input/output port 318
It is connected to the.

The RAM 314 stores calculation results in the main routine, fuel injection amount calculation routine, fuel injection timing calculation routine, etc. as necessary.

The ROM 316 stores in advance programs such as an initial routine, a main routine, a fuel injection amount calculation routine, and a fuel injection timing calculation routine, as well as various fixed data, constants, etc. necessary for these processes.

A drive circuit 320 composed of a servo amplifier for operating the spill control solenoid 226 is connected to the input/output port 318 .
The CPU 312 provides the energization duty ratio (pulse width) of the spill control solenoid 226. At this time, the position of the plunger 212 is detected by the spill position sensor 230 and fed back to the drive circuit 320.

The operation of the control circuit shown in FIG. 3 will be explained with reference to the flowcharts shown in FIGS. 4 and 5.

FIG. 4 shows a fuel injection amount control routine, which is a time interrupt routine executed at predetermined time intervals. Proceeding from interrupt step 401 to step 402,
Take in the rotation speed Ne from the rotation angle sensor 234,
Further, in step 403, the accelerator opening degree _Accp is read from the accelerator opening degree sensor 32.

In step 404, the CPU 312 determines the rotational speed Ne.
and the basic injection amount Q _B is calculated based on the accelerator opening degree A _ccp . That is, the basic injection amount is calculated by performing interpolation calculations using the two-dimensional map shown in FIG.

In step 405, the CPU 312 determines the rotational speed Ne.
Upper limit of basic injection amount when intake pressure is 760mmHg.
Calculate Q _FULL . That is, the upper limit value Q _FULL is calculated by performing interpolation calculations using the one-dimensional map shown in FIG.

At step 406, the CPU 312
The upper limit value Q _FULL found in 405 is
Correction is made using the intake pressure correction coefficient _K1 and the intake pressure change correction coefficient _K2 stored in . In other words, calculate Q _FULL ′←K ₁・K ₂・Q _FULL . The correction coefficients K ₁ and K ₂ will be described later.

In step 407, the CPU 314 compares the corrected upper limit value Q _FULL ' with the basic injection quantity Q _B obtained in step 404, and if Q _FULL '≧Q _B , the final injection quantity Q _FIN is determined in step 408. Let be Q _B , and on the other hand,
If Q _FULL ′<Q _B , the final injection amount is determined in step 409.
Let Q _FIN be the upper limit value Q _FULL ′. As a result, the step
At 410, an energization duty ratio corresponding to the final injection amount Q _FIN is applied to the drive circuit 320 via the input/output port 318 to activate the spill control valve 4.
Activate 10. The routine then ends at step 411.

Next, the correction coefficients K ₁ and K ₂ used in step 406 of FIG. 4 will be explained with reference to the flowchart of FIG. 5. This flow is a time interrupt routine and is executed, for example, every 50 msec. Proceeding from interrupt step 501 to step 502,
Here, the intake pressure P of the intake pressure sensor 104 is taken in, and further, in step 503, the CPU 312 calculates an intake pressure correction coefficient _K1 based on the intake pressure P. That is, the intake pressure correction coefficient _K1 is calculated by performing interpolation calculation using the one-dimensional map shown in FIG. This calculation result is stored in a predetermined area of RAM 314.
Note that Fig. 8 shows the case of a diesel engine with a turbo, that is, when the intake pressure P is 760
The reason why K ₁ is small below mmHg is due to high altitude compensation, and the reason K ₁ is large when the intake pressure P is 760 mmHg or above is due to turbocharging, and when the intake pressure P increases further, K ₁ decreases rapidly. This is to prevent overcharging.

In step 504, the CPU 312 reads the intake pressure P ₀ obtained during the previous execution of this routine from the RAM 314, and reads the intake pressure P 0 obtained in step 502.
Calculate the difference between That is, the intake pressure change rate ΔP ΔP←P−P ₀ every 50 msec is calculated.

In step 505, the CPU 312 calculates an intake pressure change correction coefficient _K2 based on the intake pressure change rate ΔP. That is, an interpolation calculation is performed using the one-dimensional map shown in FIG. 9 to calculate the intake pressure change correction coefficient _K2 . This calculation result is also stored in a predetermined area of RAM 314.

In step 506, the intake pressure P is set to P ₀ and RAM
The data is stored in a predetermined area 314, and the routine ends at step 507.

As shown in FIG. 9, in the present invention, when the intake pressure change rate ΔP is larger than the predetermined value _X1 , the correction coefficient _K2 is increased to increase the upper limit value of the basic injection amount; When ΔP is smaller than the predetermined value X ₂ , the correction coefficient K ₂ is reduced to reduce the upper limit value of the basic injection amount. This improves acceleration when the intake pressure rises during acceleration, and prevents generation of black smoke when the intake pressure suddenly drops during deceleration.

Note that the basic injection amount is actually corrected based on the outputs of sensors such as a water temperature sensor, an intake pressure sensor, and an intake air temperature sensor.

[Brief explanation of the drawing]

FIG. 1 is an overall block diagram for explaining the configuration of the present invention, FIG. 2 is an overall schematic diagram showing an embodiment of a fuel injection amount control device for a diesel engine according to the present invention, and FIG. 4 and 5 are flowcharts for explaining the operation of the control circuit of FIG. 3, and FIGS. 6 to 9 are detailed block circuit diagrams of the control circuit of FIG. It is a characteristic diagram of the diesel engine used. 10... Engine body, 20... Fuel injection pump,
30... Control circuit, 32... Accelerator opening sensor, 104... Intake pressure sensor, 234... Rotation angle sensor, 226... Spill control solenoid, 230... Spill position sensor.

Claims (1)

[Scope of Claims] 1. In a diesel engine in which the input circuit of the intake pressure sensor is provided with a filter for reducing the influence of intake pulsation, the basic injection amount is determined according to the rotation speed and accelerator opening of the engine. basic injection amount calculation means for calculating an upper limit value of the basic injection amount according to the rotational speed of the engine and the intake pressure of the intake passage of the engine; a unit time of the intake pressure. intake pressure change detection means for detecting a rate of change in the intake pressure; when the rate of change in the intake pressure changes beyond a predetermined rate of change, it is assumed that there is a response delay in detecting the intake pressure, and the upper limit value of the basic injection amount is set; a basic injection amount upper limit correction means that corrects the basic injection amount so as to approach the upper limit value assuming that there is no response delay; and a basic injection amount upper limit value that compares the corrected basic injection amount upper limit value with the basic injection amount, A fuel injection amount control device for a diesel engine, comprising an injection amount calculating means for calculating an injection amount according to a comparison result, and supplying an amount of fuel to the engine according to the injection amount. 2. The diesel engine according to claim 1, wherein the basic injection amount upper limit value correction means increases the upper limit value of the basic injection amount when the intake pressure changes in a positive direction by a predetermined rate of change or more. fuel injection amount control device. 3. The diesel engine according to claim 1, wherein the basic injection amount upper limit correction means reduces the upper limit value of the basic injection amount when the intake pressure changes in a negative direction by a predetermined rate of change or more. fuel injection amount control device.