JPS62214252A - Device for controlling fuel injection timing for diesel engine - Google Patents

Abstract

PURPOSE:To prevent rise in combustion chamber temp. and increase in knocking sound by providing a means of calculating a correction for the deviation between firing timing which is detected by using a firing timing sensor and a reference position sensor and target firing timing. CONSTITUTION:An injection nozzle 34, a glow plug 36, and a firing timing sensor 38 are provided on the cylinder head 10A of a Diesel engine 10. A reference position sensor 44 detects the reference position of a crank angle from the rotation displacement of the pump driving pulley 42D of an injection pump 42. An electronic control unit 56 calculates a correction for the deviation between target firing timing and detected firing timing and corrects fuel injection timing. Thereby, rise in combustion chamber temp. and increase in knocking sound can be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fuel injection timing control device for a diesel engine, and particularly relates to a fuel injection timing control device for a diesel engine equipped with an ignition II resen
Related to improvement of fuel injection timing system m + gas charging for diesel engines, which is suitable for use in electronically controlled diesel engines for I, and uses the youth timing detected using an ignition timing sensor and a reference position sensor to correct the fuel injection timing. .

[Conventional technology]

When controlling the fuel injection timing to optimize the exhaust gas purification performance of diesel engines, especially automobile diesel engines, the position of the timer piston of the fuel injection pump (hereinafter referred to as timer position) is detected, and the detected timer position and A so-called timer position feedback control has been proposed in which a timer control valve controlling the position of the timer piston is feedback-controlled in accordance with a difference from a target timer position determined from the engine operating state. In addition, in this timer position feedback control, J3 is specially designed to solve the problem of injection timing deviation due to variations in the initial setting of the fuel injection pump and injection timing deviation due to changes in atmospheric pressure, fuel properties, etc. Kaisho 57-28842,
JP-A-58-25584, JP-A-58-192935,
In JP-A-59-153942, etc., an ignition timing sensor such as a flame sensor is installed in the combustion chamber, and the ignition timing sensor detects the ignition timing in the combustion mold (the timing at which combustion light rises due to ignition or the pressure inside the cylinder). By feedback-controlling the detection result of the timing of sudden rise due to combustion, the timer control valve is feedback-controlled so that the detected ignition timing becomes the target ignition timing determined by, for example, the engine speed and the accelerator opening. Ignition timing feedback control has also been proposed.

[Problems to be solved by the invention]

However, in this fire timing feedback control, the difference between the target ignition timing and the detected ignition timing is calculated every time.
Since the opening degree of the timer control valve is feedback-controlled based on the difference, when there is a large variation in the detected ignition timing, such as at high speed and high load, the injection timing is overcorrected due to the influence of the variation, causing the injection timing to be It will change. or,
If the tip of the ignition timing sensor deteriorates and the amount of light passing through the glass rod decreases, even if fuel is injected at the same injection timing, the detected ignition timing will be delayed, resulting in unnecessary feedback control , l'SuJ timing is reversely advanced. To solve these problems, when controlling fuel injection timing according to engine operating conditions, in operating regions where ignition detection variation is small, the timer control valve is adjusted according to the difference between the target ignition timing and the detected ignition timing. On the other hand, in an operating region where there are large variations in fire detection, it is conceivable to perform timer position feedback control of the timer control valve according to the difference between the target timer position and the detected timer position. However, in such a control method, learning is performed in order to feedback control the tube fire delay in a specific engine operating range (for example, low accelerator opening), and the learned value is used in all operating ranges. Although the ignition delay is corrected accurately in the operating range where learning is not performed, accurate correction cannot be made in the operating range where learning is not performed. In addition, in the high load range of the engine, there is less ignition delay due to shadow costs such as low pressure and low water temperature than in the low load range, so the ignition delay learned in the low load range can be applied directly to the high load range. When used for correction during a young age, there is a problem in that the angle is advanced too much due to overcorrection, which may cause problems such as an increase in the combustion room temperature of the engine and an increase in knocking noise.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and is capable of sufficient correction in the fr1 range where correction is required during youth, and does not overcorrect in areas where correction is not so necessary. An object of the present invention is to provide a fuel injection timing control device for a diesel engine.

[Means to solve the problem]

The present invention provides a fuel injection timing control 2'Il arrangement for a diesel engine that uses the youth period detected using a youth period sensor and a reference position sensor to correct the fuel injection timing.
The gist of the invention is shown in Fig. 1, which includes means for calculating a correction value for the deviation between the target ignition timing and the detected ignition timing, and at least one of an upper limit value and a lower limit value depending on the operating condition for the calculated correction value. The above object is achieved by providing a means for correcting the fuel 'Q allocation timing.

[Effect]

In the present invention, the youth period of a diesel engine is detected using a youth period sensor and a reference position sensor, and when controlling the fuel injection timing of the engine, based on the detected ignition timing, A correction value for the deviation between the target ignition timing and the detected ignition timing is calculated, and the fuel injection timing is corrected by setting at least one of an upper limit and a lower limit value in accordance with the operating state to the calculated correction value. Therefore, in the operating range where sufficient correction is required, sufficient correction is performed.
Over-correction does not occur in operating ranges where correction is not so necessary. Therefore, when the engine is under high load and the engine is over-advanced due to over-correction, the impact costs such as engine vibration, noise, and
An increase in Ox can be prevented.

[Example] ゛Hereinafter, the fuel consumption of the diesel engine according to the present invention, l〕1j
, Q9An embodiment of the timing control device will be explained in detail. As shown in FIG. 2, this embodiment includes an intake air temperature sensor 12 disposed downstream of an air cleaner (not shown) for detecting the temperature of intake air. A turbocharger 14 is provided downstream of the intake air temperature sensor 12 and includes a turbine 14A rotated by thermal energy of exhaust gas and a compressor 14B rotated in conjunction with the turbine 14A. The upstream side of the turbine 14A of the turbocharger 14 and the downstream side of the compressor 14B are communicated via a wastegate valve 15 for preventing an excessive rise in intake pressure. The venturi 16 downstream of the compressor 14B includes:
A main intake throttle valve 18 is provided, which is configured to rotate non-linearly in conjunction with an accelerator pedal 17 disposed at the driver's seat, for restricting the flow m of intake air when the vehicle is idling. The opening degree of the accelerator pedal 17 (hereinafter referred to as accelerator opening degree) is determined by the accelerator position sensor 20.
has been detected by. A sub-intake throttle valve 22 is provided in parallel with the main intake throttle valve 18 , and the opening degree of the sub-intake throttle valve 22 is controlled by a diaphragm device 24 . Negative pressure generated by a negative pressure pump 26 is supplied to the diaphragm device 24 via a negative pressure switching valve (hereinafter referred to as VSV) 28 or 30. An intake pressure sensor 32 for detecting the pressure of intake air is provided downstream of the intake throttle valve 18.22. In the cylinder head 10A of the diesel engine 10,
An injection nozzle 34 whose tip faces the engine combustion chamber 10B, a glow plug 36, and a fire timing sensor 38 are provided. Further, the cylinder block 10C of the diesel engine 10 is equipped with a water temperature sensor /lO for detecting the engine cooling water temperature. Fuel is fed under pressure to the injection nozzle 34 from an injection pump 42 . The injection pump 42 includes a pump drive shaft 42A that rotates in conjunction with the rotation of the crankshaft of the diesel engine 10, and a feed pump 42B (second pump) that pressurizes fuel and is fixed to the pump drive shaft 42A. (The figure shows a 90" expanded state), a fuel pressure adjustment valve 42G for adjusting the fuel supply pressure, and the pump drive shaft 42A.
A reference position sensor 44 composed of, for example, an RI magnetic pickup is used to detect a crank angle reference position, for example, top dead center (TDC) from the rotational displacement of a pump drive pulley 42D fixed to the pump drive pulley 42D, and a reference position sensor 44 is also fixed to the pump drive , an engine rotation sensor 46 made of, for example, an electromagnetic pickup, provided on the roller ring 42 for detecting the engine rotation speed and the position of the missing teeth from the rotational displacement of the gear 42E having missing teeth corresponding to the number of cylinders; a roller ring 42H for reciprocating the face cam 42F and the plunger 42G and changing the timing;
The injection timing is controlled by controlling the timer piston 42J (FIG. 2 shows a 90° expanded state) for changing the position around the roller ring 421-1 and the position of the timer piston 42J. timing a to do
I (l tit valve (hereinafter referred to as TCV) 48, an electromagnetic spill valve 50 for controlling the fuel injection amount by changing the timing of releasing fuel from the plunger 42G via the spill boat 42K, and a fuel cut valve 48. The glow plug 36 is provided with a fuel cut valve 52 for preventing fuel backflow and a delivery valve 42L for preventing backflow of the fuel.A glow current is supplied to the glow plug 36 via a glow relay 37. As shown in detail in FIG. 3, the ignition timing sensor 38 includes a cylindrical case 38A that is inserted and fixed into the cylinder head IOA of the diesel engine 10, and a cylindrical case 38A that is inserted into the center of the case 38A. 1=, one guide 38B made of quartz glass, for example, for transmitting combustion light, and one for detecting the light transmitted by the guide 38B and converting it into electric No. 15, for example. A light receiving element 38C made of a silicon photodiode is provided.The intake temperature sensor 12, the accelerator position sensor +120, the intake pressure sensor 32, the ignition timing sensor 38, and the water temperature sensor 40.
, a reference position sensor 44, an engine rotation sensor 46, a glow current sensor 54 that detects the glow current flowing through the glow plug 36, a key switch, an air conditioner switch, a neutral safety switch output, a single signal, etc., are controlled by an electronic control unit (hereinafter referred to as (referred to as ECU) 56 for processing, and the output of the ECU 36 causes the VS
V28.30, glow relay 37, TCV=18, electromagnetic spill valve 50, fuel cut valve 52, etc. are controlled. As shown in detail in FIG. 4, the ECU 36 is connected to a central processing unit (hereinafter referred to as CPtJ) 56 for performing various arithmetic operations, and a read-only memory (hereinafter referred to as CPtJ) for storing control programs and various data. (hereinafter referred to as ROM) 56B, a random access memory (hereinafter referred to as RAM) 56C for temporarily storing calculation data etc. in the CPIJ 56A, a clock 56D that generates a clock signal, and a buffer 56E. The output of the water temperature sensor 4o is input, the output of the intake temperature sensor 12 is input via the buffer 56F, and the buffer 56
A multiplexer (hereinafter referred to as MPX) 56 for sequentially taking in the output of the intake pressure sensor 32 inputted via G, the output of the accelerator position sensor 20 inputted via the buffer 56H, etc. An analog-to-digital converter (hereinafter referred to as an A/D converter) 56 for converting the analog signal output to the MPX 56 into a digital signal.
L, an input/output port 56M for taking the output of the A/D converter 56 into the CPU 56A, a starter signal inputted via the buffer 56N, an air conditioner No. 18 inputted via the buffer 56P, and a buffer 56Q. The CPU 56 receives the torque converter signal input via the ignition signal, the output of the 101 sensor 38 at the time of ignition input via the waveform shaping circuit 56R, etc.
the input/output port 563 for inputting the output to the input interrupt port ICAP2 of the CPU 56A; into the same input interrupt port ICA of the CPU 56A.
A waveform shaping circuit 56T for directly taking in the output of the engine rotation sensor 46 to the CPU 5
6A input interrupt port ICAPI; a drive circuit 56V for driving the electromagnetic spill valve 50 according to the calculation result of the CPLJ 56A; A drive circuit 56W for driving the TCV 48 according to the result, a drive circuit 56X for driving the fuel cut valve 52 according to the calculation result of the CPLJ 56A, and each of the generation devices are connected to each other to generate data. and a common bus 56Y for transferring instructions.
The AM56G is equipped with a backup RAM that receives power backup even when the engine is stopped and its stored contents are not lost. Here, the ignition signal output from the waveform shaping circuit 56R is
The waveform shaping circuit 56 that is input to the input/output boat 568, not the input interrupt boat ICAP2 of the PU 56A, is input to the same input interrupt boat ICAP2.
This is to distinguish it from the reference signal of the T output. Hereinafter, control of fuel injection timing in the embodiment will be explained. This embodiment is executed according to the flowchart shown in FIG. 5. That is, in order to calculate the feedback of the injection timing with respect to the crank angle, the 5Q m5eo routine shown in FIG. 5A is executed. In this 50 m5ec routine, first, step 110 is entered, and by searching a map of, for example, the engine speed NE and the accelerator opening degree ACCP, the basic target timing CAbas of the fuel injection DI is determined.
Find e. Next, in step 120, on the accelerator opening Accp and the ignition timing correction term as shown in FIG.
The map of the relationship between the lower limit value GIGm and the accelerator opening A cc
Search by p. Next, the upper and lower limit values GIGm of the ignition timing correction term searched and found in step 130
and the control value GIG of the ignition timing correction term, and the above,
A value that does not exceed the lower limit value GIGm is stored as a learned value GIGa of the ignition timing correction term. In this way, the upper and lower limits of the ignition timing correction term GIG are guarded. Similarly, only the lower limit value of the January correction term at the time of ignition is the set value 11. Next, the process proceeds to step 140, where the basic target time CA
base and the calculated learning value GIGa of the ignition timing correction term
The sum is calculated as shown in the following equation (1) and substituted into the target injection time TrATRGca for the crank angle, and correction is added. TRGca4-CAbase+G T Ga-(1) Next, in step 150, the detected fuel injection timing (actual injection timing) ACTea is subtracted from the calculated target injection timing TRGCa to calculate the difference between the two. Calculate 〇A. ΔCA 4-TRGca-ACTca (2) Next, in step 160, an integral term ΔDi for duty-controlling the TCV 48 is calculated from the calculated injection timing difference ΔCA.
and calculate the proportional term Dp. Next, in step 170, the integral term ΔDi and the proportional term Dp are added to or subtracted from the control duty ratio Di at that time as shown in the following equation to calculate a final duty ratio, and this routine ends. 0=01 ±ΔDi +:Dρ ・・・・・・
(3) Next, a routine for calculating the control value GIG of the ignition timing correction term will be explained as shown in FIG. 5 ([3). In this routine, step 1 is set for 1 second fσ.
Proceeding to 80, it is determined whether the engine has started. If the determination result is negative, the process proceeds to step 190, where it is determined whether the accelerator opening degree Accp is 16% or less. If the determination result is positive, step 2001. : Proceed to determine whether the fuel injection MQ to the engine is 5 mm3/st. In steps 180 to 200 above, it is determined whether the conditions for calculating the ignition timing correction term G■G have been met. If the determination result in step 2000 is positive, step 21
Proceed to 0, engine rotation INE and accelerator opening A cc
By searching the map of p, the target ignition timing T
Calculate RG ig. Next, in step 220, the actual ignition timing A CT t detected by the ignition timing sensor 38 is determined.
Difference ΔGIG between g and the calculated target ignition timing TRG io
is calculated using the following equation (4). 80IG4-ACTig-TRGig ・・・・・・(
4) Next, in step 230, the ignition timing difference ΔGIG calculated by equation (4) is added to the stored ignition timing correction term GIG as shown in the following equation (5) to obtain the ignition timing correction term GIG. calculate. GIG”GIG+ (1/8)ΔGIG・・・・・・(
5) Next, the fire timing correction term GIG calculated in step 240 is stored in the backup RAM in the RAM 56C. As a result, even when the engine is turned off, the stored ignition timing correction term GIG is not deleted, and the correction value for the ignition delay immediately before the engine is stopped is reliably reflected in the fuel injection timing after restarting the engine. I can do it. In this case, the injection timing at startup can be set appropriately to eliminate white smoke in the exhaust gas and engine vibration. Note that if the determination result in step 180 is positive, step 190
If the determination result in step 200 is negative, the bone period correction term GIG is not calculated. As described above, in this embodiment, as the engine load increases, the upper and lower limits GTGm of the youth period correction term GIG can be made smaller using the map shown in FIG.
Fuel injection timing is no longer overcorrected, and engine vibration and noise and NOX in exhaust gas can be prevented. Additionally, even if the detected ignition timing is delayed due to a drop in engine output due to extreme deterioration of the ignition timing sensor 38 or breakage of the glass at its tip, an upper limit value of the correction term is provided, so that the fuel can be reduced during high loads. Since the injection timing is not controlled to the advanced side, an abnormal rise in combustion room temperature does not occur. In this embodiment, the value of the ignition timing correction term is calculated by providing an upper limit value and a lower limit value that vary depending on the load, but it is also possible to calculate the value by providing only an upper limit value or a lower limit value. In this case, the settings are simple. Furthermore, the setting value of the maximum value GGI11 of the youth period correction term is not limited to the relationship represented by the curve as shown in FIG. 6, but the correction range can be set by the setting value of the equation . Further, the setting of the upper limit value (or lower limit value) of the ignition timing correction term is not limited to the correction range based on the accelerator opening degree Accp shown in FIG. The range of the correction fIGIG of the ignition timing correction term may be set based on the engine speed NE, fuel injection ff1Q, or a combination thereof. In addition, the maximum range of 1iffGIG of the correction term shown in FIG.
It does not directly set the value GIG, but the value G I
Absolute value I of the value obtained by subtracting °30°C CΔ from G by crank angle
The maximum range is set based on GIG-301. Further, in this embodiment, the present invention provides an electromagnetic spill valve 5.
However, the scope of application of the present invention is not limited to this, and is applicable to fuel injection m control actuators other than electromagnetic spill valves. It is clear that the invention can be similarly applied to general diesel engines equipped with.

【Effect of the invention】

As explained above, according to the present invention, the fuel injection timing can be sufficiently corrected in the region where correction is required, and no overcorrection is made in the necessary region. Therefore, for example, if the correction term for low load is used as is for high load, the fuel injection timing will be advanced unnecessarily and combustion will occur! It has the excellent effect of being able to eliminate the occurrence of problems such as raising the engine speed and making knocking noise louder.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the gist of the present invention;
The figure shows the overall configuration of an embodiment of an electronically controlled diesel engine for automobiles to which the present invention is adopted, and is a sectional view including a partial block diagram. Fig. 4 is a vertical cross-sectional view showing b”lli.
Similarly, a block diagram showing the configuration of the electronic control unit,
FIG. 5 is a flowchart showing a routine for controlling the fuel injection timing in the embodiment, and FIG. 6 is a diagram showing an example of the relationship between the length correction value and the accelerator opening used in the routine. Similarly, FIG. 7 is a graph showing an example of the relationship between the ignition timing correction value and the engine speed. DESCRIPTION OF SYMBOLS 10... Diesel engine, 20... Accelerator position sensor, Accp... Accelerator opening degree, 38... Ignition timing sensor, 42... Injection pump, 42J... Timer piston, 44... Reference 2 sensor, 46... Engine rotation sensor, NE... Engine rotation speed, 48... Timing control valve (TCV), 56... Electronic control unit (ECLI), Q... Fuel injection M. T Ra to...Target ignition timing, A CT io...Detected (actual) ignition timing, ΔIG...
・Difference in ignition timing, ΔIGIII...Learned value, TRGCa...Target injection timing, GIG...Ignition timing correction term, GIGIII...Upper and lower limit values of ignition timing correction term, GI
Ga...Learned value of ignition timing correction term, agent high
Arrow theory, Keiyu Matsuyama Figure 6 Figure 7 NE (XIO3rpm)

Claims (1)

[Claims] (1) In a diesel engine fuel injection timing control device that uses the ignition timing detected using an ignition timing sensor and a reference position sensor to correct the fuel injection timing, a correction value is calculated for the discrepancy between the target ignition timing and the detected ignition timing. A fuel injection timing for a diesel engine, comprising: means for correcting the fuel injection timing by setting at least one of an upper limit value and a lower limit value to the calculated correction value depending on the operating state. Control device.