JPH05125973A - Fuel injection quantity control device for diesel engine - Google Patents

Abstract

PURPOSE:To provide a fuel injection quantity control device for a diesel engine in which a basic injection quantity is corrected based on a correction characteristic determined according to the relationship between fuel temperature and the kind of fuel used, so that the accuracy of fuel injection quantity control is enhanced. CONSTITUTION:A fuel identification means 307 identifies the kind of fuel used according to the relationship between the amount of correction of engine speed that an engine speed correction amount computing means 303 computes according to the deviation between a desired speed of a diesel engine 300 in a predetermined stable driving state and actual engine speed, and fuel temperature that a fuel temperature detection means 306 detects. Then a correction means 308, according to the relationship between a correction characteristic selected by the kind of fuel used and the fuel temperature, corrects the commanded quantity of fuel injection which is computed by a commanded fuel quantity computing means 304. A fuel injection control means 305 performs injection control for the corrected quantity of injection commanded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for a diesel engine.

[0002]

2. Description of the Related Art As a conventional technique for controlling the fuel injection amount of a diesel engine, there is a fuel injection control device for a diesel engine disclosed in Japanese Patent Laid-Open No. 1-290945. The fuel injection control device for the diesel engine obtains the change characteristic of the injection amount of the fuel injection pump with respect to the change in the fuel temperature when the diesel engine is operating in a predetermined stable state, and the change characteristic, the fuel temperature and each operation. The optimal fuel injection amount in each operating state is corrected and calculated based on the state.

[0003]

However, the degree to which the fuel temperature change described above contributes to the change in the injection amount of the fuel injection pump is small, and engine friction and the load of auxiliary machinery have a great influence. Therefore, if the optimum fuel injection amount in each operation state is corrected and calculated based on the fuel injection amount change characteristic in the stable operation state with respect to the fuel temperature, there is a problem in that the control accuracy of the fuel injection amount cannot be ensured. The present invention has been made in order to solve the above problems, since the difference between the individual characteristics of the fuel temperature characteristics of the injection pump is small, based on the basic correction characteristics obtained from the relationship between the fuel temperature and the fuel type, An object of the present invention is to provide a fuel injection amount control device for a diesel engine that can improve the accuracy of fuel injection amount control in each operating state by correcting the basic injection amount.

[0005]

[Means for Solving the Problems] As a specific means for achieving the above object, as shown in FIG. 1, various engine information such as engine speed and accelerator opening is input to operate the diesel engine 300. The operating state detecting means 301 for detecting the state, the basic injection amount calculating means 302 for calculating the basic injection amount of fuel based on the detection result of the operating state detecting means 301, and the diesel engine 300 are brought into a predetermined stable operating state. A rotation speed correction amount calculating means 303 for calculating a rotation speed correction amount based on a deviation between a target rotation speed and an actual rotation speed at a certain time, and a command injection of fuel based on the rotation speed correction amount and the basic injection amount. Diesel engine 3 having command injection amount calculation means 304 for calculating the amount and fuel injection control means 305 for controlling the injection of the calculated command injection amount of fuel
No. 00 fuel injection amount control device, fuel temperature detection means 306 for detecting the fuel temperature, fuel type determination means 307 for determining the type of fuel used from the relationship between the rotational speed correction amount and the fuel temperature, and the fuel Provided is a fuel injection amount control device for a diesel engine, comprising: a correction unit 308 that corrects the command injection amount based on a relationship between a correction characteristic selected according to a determination result of the type determination unit 307 and the fuel temperature. To be done.

[0006]

The operation of the fuel injection amount control device for the diesel engine 300 is as follows. The rotation speed correction amount calculation means 303 calculates the rotation speed correction quantity and the fuel detection means 306 based on the deviation between the target rotation speed and the actual rotation speed of the diesel engine 300 when in a predetermined stable operation state.
From the fuel temperature detected by the fuel type discriminating means 3
07 determines the type of fuel used. Then, the correction unit 308 corrects the command injection amount of the fuel calculated by the command injection amount calculation unit, based on the relationship between the correction characteristic selected according to the type of fuel used and the fuel temperature. The fuel injection control unit 305 controls the injection of the corrected command injection amount.

[0007]

Embodiments of the present invention will be specifically described with reference to the drawings. 2 is a configuration diagram showing a cross section of a fuel injection pump to which the present invention is applied, and FIG. 3 is an enlarged cross sectional view taken along the line AA in FIG. The fuel injection pump 1 is an electromagnetic spill type based on a known Bosch type distribution type fuel injection pump. Half that in synchronization with the engine crankshaft
The drive shaft 2 rotating at the speed of rotatably drives the vane type feed pump 3. In FIG. 2, the vane type feed pump 3 viewed from the axial direction is also shown. The vane feed pump 3 regulates the fuel, which is introduced from the suction port 4 and pressurized, to a predetermined pressure by the fuel pressure regulating valve 5, and then supplies the fuel to the fuel chamber 7 formed in the pump housing 6.

Further, the drive shaft 2 rotationally drives the plunger 9 via the coupling 8. The coupling 8 restrains only the rotation of the plunger 9 and integrally rotates and drives the plunger 9 to freely reciprocate in the axial direction. A face cam 10 is integrally provided on the plunger 9. The face cam 10 has four cam peaks corresponding to the number of cylinders of the engine, and is pressed against the cam roller 12 by the spring 11. Due to the sliding contact between the cam roller 12 and the face cam 10, the plunger 9 is reciprocated in the axial direction a number of times corresponding to the number of cylinders during one rotation.

The plunger 9 is slidably and precisely fitted to a head 13 fixed to the housing 6, and the head 13 and the end surface of the plunger 9 form a pump chamber 14. The fuel sucked from the fuel chamber 7 through the suction hole 16 is pressurized by the reciprocating plunger 9. The high-pressure fuel pressurized in the pump chamber 14 is sent to the pressure feed valve 18 of each cylinder via the distribution port 17 selected by the rotational position of the plunger 9, and is pressure-fed to the injection nozzle of each cylinder of the engine body. It is then injected into the combustion chamber.

The pump chamber 14 communicates with an electromagnetic spill valve 22 via a high pressure passage 21. The electromagnetic spill valve 22 has an overflow passage 23 communicating with the high pressure passage 21 and the fuel chamber 7.
And are opened and closed by energizing. When the coil 24 is energized, the needle valve 25, which is a pilot valve, closes the orifice 26, the fuel in the spool chamber 27 cannot flow out, and the spool 28, which is a main valve, closes the valve. When the coil 24 is de-energized, the fuel in the spool chamber 27 flows out to the overflow passage 23, the spool 28 is lifted and the valve is opened. Therefore, when the electromagnetic spill valve 22 is de-energized during the compression stroke of the plunger 9, the high-pressure fuel escapes to the fuel chamber 7 through the overflow passage 23 and is not pressure-fed to the pressure-feed valve 18, so that fuel injection is performed. Be stopped. The fuel injection amount in each cylinder is controlled by controlling the timing at which the power supply to the electromagnetic spill valve 22 is cut off.

A cam roller 1 in sliding contact with the face cam 10.
2 is held by a roller ring 31. This roller ring 31 is provided so as to be rotatable within an angle range of several tens of degrees,
The rotation position is controlled by the timer piston 32 via the pin 33. The sliding position of the cam roller 12 and the face cam 10 is deviated by the rotating position of the roller ring 31, the phase of the reciprocating motion of the plunger 9 relative to the rotational angle position of the drive shaft 2 is changed, and the fuel injection timing is changed. There is. The roller ring 31, the timer piston 32, etc. form a hydraulic timer mechanism for controlling the fuel injection timing.

The position of the timer piston 32 is determined by the pressure difference between the high pressure chamber 34 and the low pressure chamber 35 and the load of the timer spring 36. The high pressure chamber 34 communicates with the high pressure side of the vane type feed pump 3, that is, the fuel chamber 7 via a throttle not shown, and the low pressure chamber 35 communicates with the low pressure side of the vane type feed pump 3. Then, the high pressure chamber 34 and the low pressure chamber 35 are communicated with each other via the electromagnetic adjustment valve 37, and the pressure of the high pressure chamber 34 is adjusted by the opening degree of the electromagnetic adjustment valve 37, and the position of the timer piston 32 is adjusted. Although the timer piston 32 is actually provided so that the sliding direction is orthogonal to the drive shaft 2,
In order to clearly show the structure, it is expanded 90 ° on the drawing and shown as in FIG.

In order to detect the rotation of the drive shaft 2 and the lift timing of the plunger 9, a disc 42 having a protrusion 41 on its outer periphery is fixed to the drive shaft 2 and a rotation angle sensor for detecting the protrusion 41 of the disc 42 is provided. 43 is fixed to the roller ring 31. As shown in FIG. 3, the protrusion 4 of the disk 42
1 are arranged at 90 ° / 16 (= 5.625 °) intervals, and disk 4
There is a missing portion 44 for two protrusions for every 90 ° of 2. Then, the injection pump drive shaft 2 rotates 90 °, that is, the engine 18
The missing portion 44 is detected for every 0 ° crank angle and used as a reference angle signal, and the projection 41 is detected for every 11.25 ° crank angle of the engine and used as an angle signal.

Signals from an accelerator position sensor 51, a cooling water temperature sensor 52, an intake air temperature sensor 53, etc., which give an engine operating state signal, are input to an electronic control unit (ECU) 50 having a microcomputer. Further, the fuel injection pump 1 is provided with a fuel temperature sensor 54 that detects the fuel temperature of the fuel chamber 7, and detects the fuel temperature and inputs it to the electronic control unit 50.

The electronic control unit 50 calculates the injection timing and the injection amount based on the engine state information such as the operation state signal and the signal from the rotation angle sensor 43. The injection amount is corrected according to the detection signals from the fuel temperature sensor 54 and the rotation angle sensor 43. Then, the opening degree of the electromagnetic adjustment valve 37 is controlled to realize the calculated injection timing, and the opening / closing timing of the electromagnetic spill valve 22 is controlled to realize the calculated and corrected injection amount.

The correction process of the fuel injection amount based on the above mechanical structure will be described. The main leaks of high-pressure fuel that affect the fuel injection amount are high-pressure fuel in the pump chamber 14 leaking into the fuel chamber 7 through the sliding contact portion between the plunger 9 and the head 13, and high-pressure fuel in the spool chamber 27. Fuel is spool 2
8 and the spill valve 22 main body through a sliding contact portion to leak into the overflow passage 23. Due to these leaks, fuel corresponding to the lift amount of the plunger 9 is not pumped to the pump valve 18,
The actual fuel injection amount decreases. The injection amount to be commanded is corrected by presuming this reduction amount in advance.

FIG. 4 is a flow chart showing the actual injection amount control processing by the microcomputer in the electronic control unit 50. When the process starts, in step 101,
The operating state signal of the diesel engine detected by the accelerator position sensor 51, the cooling water temperature sensor 52, the intake air temperature sensor 53 and the like is read, and the engine speed is calculated from the generation interval of the reference angle signal from the rotation angle sensor 43. Further, the fuel temperature from the fuel temperature sensor 54 and the correction amount of the idle speed control obtained in the flowchart of FIG. 5 are read. In step 102, a basic injection amount Q ₀ that gives a command injection amount suitable for the operating state is calculated from the information on the engine state and the load.

In step 103, correction coefficients K ₁ and K ₂ for correcting the actual decrease in the injection amount due to the leakage of the high pressure fuel are calculated. The correction coefficient K ₁ is a coefficient for correcting the change in leakage corresponding to the change in viscosity due to the fuel temperature,
As shown in FIG. 6, a larger value is given as the fuel temperature detected by the fuel temperature sensor 54 is higher. The correction coefficient K ₁ is obtained from the relationship between the fuel temperature and the correction amount of the idle speed control that corrects the change in leakage due to the difference in the type of fuel used. The correction coefficient K ₂ is a coefficient for correcting an increase in leakage when the engine speed is low, and a larger value is given as the engine speed is lower, as shown in FIG. 7.

As shown in FIGS. 6 and 8, the correction coefficient K ₁ is given a larger value as the correction amount of the idle speed is larger. This corresponds to the use of diesel fuel having a low viscosity such as No. 3 gas oil or No. 3 gas oil in colder regions. The type of diesel fuel to be used is assumed from the idle speed correction amount at a predetermined temperature, and leakage is corrected according to its viscosity.

Here, in the determination of the fuel type from the correction amount of the idle speed, the fuel temperature is 50 as shown in FIG. 8 under the condition that the idle stability condition is satisfied at a predetermined engine temperature.
The correction amount in the case of ℃ is within a predetermined value range (for example, -30 rpm to
(+50 rpm), it is judged to be No. 2 diesel oil that enters the A region, if +50 rpm is larger, it is judged to be No. 3 diesel oil and special No. 3 diesel oil, and if it is less than -30 rpm, it is No. 1 diesel oil that enters the B region. To judge. The characteristic curve shown in FIG. 6 according to the determination result (A '), (C' ), determining the correction factor K ₁ to select one of (B '). In the present embodiment, the correction coefficient K ₁ is changed stepwise with respect to the idle rotation speed correction amount, but it is of course possible to change it continuously.

When the two correction coefficients K ₁ and K ₂ are calculated in step 103 as described above, the process proceeds to step 104. In step 104, the two correction coefficients K ₁ and K ₂ are multiplied to calculate a total correction coefficient K = K ₁ · K ₂ . Next, at step 105, the basic injection amount Q _O is corrected by the total correction coefficient K to calculate the command injection amount Q _FIN = Q _O · K. And
By an interrupt process (not shown), the electromagnetic spill valve 22 is de-energized with the spill angle corresponding to the command injection amount Q _FIN corrected and calculated in step 105, and the fuel injection is ended.

The flow chart of FIG. 4 shows the electronic control unit 5
It is a flow chart which shows the actual idle speed control processing in the microcomputer in 0. When the process is started, in step 201, the accelerator position sensor 51,
The operation state signal of the diesel engine detected by the cooling water temperature sensor 52, the intake air temperature sensor 53, etc. is read, and the engine speed is calculated from the generation interval of the reference angle signal from the rotation angle sensor 43. Further, the vehicle speed is input from a vehicle speed sensor (not shown). In step 202, it is judged whether or not the engine is in the idle stable state, and if it is in the stable state, a target idle speed is calculated in step 203 according to a predetermined arithmetic processing program, and in step 204, the target speed and the actual speed are calculated. The deviation is calculated, and the routine proceeds to step 205, where the rotation speed correction amount (injection amount) is calculated. Then, the calculated rotation speed correction amount is used as information of the injection amount control process as described above.

As described above, the apparatus according to the present embodiment first calculates the deviation between the target idle speed and the actual speed in the idle speed control, and based on this deviation the actual injection amount due to the leakage of high-pressure fuel. In order to correct the decrease, an idle speed correction amount is calculated. Since the contribution of the influence of the fuel temperature to the idle speed correction amount is small, it is only necessary to determine the type of fuel used from the relationship with the fuel temperature, and based on this determination result, the reduction amount of the actual injection amount is reduced. with selecting a preset characteristic for obtaining the correction factor K ₁ for correcting the correction coefficient K ₁ depending on the fuel temperature
Ask for. Then, the basic injection amount Q _O is corrected by the correction coefficient K ₂ obtained for correcting the leakage of high-pressure fuel according to the engine speed, and the correction coefficient K ₁ to correct the command injection amount Q.
Calculate _FIN . Therefore, the accuracy of the fuel injection amount control is enhanced as compared with the case where the correction coefficient for the entire operating region is simply obtained from the relationship between the idle speed correction amount and the fuel temperature.

[0024]

As described above, the present invention has the above-mentioned structure, and sets the characteristics for correcting the change in the injection amount due to the leakage in the stable operation state of the diesel engine according to the type of fuel used, Since the above-mentioned characteristic is selected based on the determination result of the fuel type and the fuel injection amount is corrected according to the fuel temperature, the fuel with high accuracy for the entire operating range is compared with the case where the correction is performed only according to the fuel temperature. There is an effect that the injection amount can be controlled.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a complaint.

FIG. 2 is a configuration diagram showing a cross section of a fuel injection pump to which the present invention is applied.

3 is an enlarged cross-sectional view taken along the line AA in FIG.

FIG. 4 is a flowchart showing an injection amount control process.

FIG. 5 is a flowchart showing idle speed control processing.

FIG. 6 is a characteristic diagram showing a correction coefficient with respect to a fuel temperature.

FIG. 7 is a characteristic diagram showing a correction coefficient with respect to a rotation speed.

FIG. 8 is a characteristic diagram showing a relationship between kinematic viscosity characteristics of various fuels and temperature.

[Explanation of symbols]

1 ... Fuel injection pump, 2 ... Drive shaft, 7 ... Fuel chamber, 9 ... Plunger, 22 ... Electromagnetic spill valve, 2
3 ... overflow passage, 43 ... rotation angle sensor, 50 ... electronic control unit (ECU), 54 ... fuel temperature sensor, 30
0 ... Diesel engine, 301 ... Operating state detecting means, 302 ... Basic injection amount calculating means, 303 ... Rotation speed correction amount calculating means, 304 ... Command injection amount calculating means,
305 ... Fuel injection control means, 306 ... Fuel temperature detection means, 307 ... Fuel type determination means, 308 ... Correction means

Claims (1)

[Claims] 1. An operating state detecting means for detecting an operating state of a diesel engine by inputting various engine information such as an engine speed and an accelerator opening degree, and a basic fuel based on a detection result of the operating state detecting means. A basic injection amount calculation means for calculating an injection amount, and a rotation speed correction amount for calculating a rotation speed correction amount based on a deviation between a target rotation speed and an actual rotation speed when the diesel engine is in a predetermined stable operation state. Computation means, instruction injection quantity computation means for computing a command injection quantity of fuel based on the rotational speed correction quantity and the basic injection quantity, and fuel injection control means for controlling injection of the calculated command injection quantity of fuel. In a fuel injection amount control device for a diesel engine, a fuel temperature detecting means for detecting a fuel temperature, and a fuel type for discriminating a kind of fuel to be used from a relationship between the rotational speed correction amount and the fuel temperature. A fuel injection amount of a diesel engine, comprising: a determining unit; and a correcting unit that corrects the command injection amount based on a relationship between a correction characteristic selected according to a determination result of the fuel type determining unit and the fuel temperature. Control device.