JPS60164645A - Controlling method of fuel injection amount in diesel-engine - Google Patents

Abstract

PURPOSE:To enhance the economy of fuel consumption and as well to prevent the generation of smoke to satisfy the characteristic of exhaust gas, by setting the amount of fuel injection for all engine cylinders or specific engine cylinders, to a value less than a basic fuel injection amount. CONSTITUTION:When judgement is made such that an engine is under deceleration, judgement is made on whether the rotational speed NE of the engine is less than a first predetermined value 1,200rpm or not, and if it is above the predetermined value, fuel injection allowing flags F1-F4 for all engine cylinders is reset to inhibit fuel injection for all engine cylinders. Further, if the rotational speed NE is less than the first predetermined value, judgement is made on whether the rotational speed NE exceeds a second predetermined value 800rpm or not, and if it exceeds the value, the fuel injection allowing flags F2, F3 for the second and third engine cylinders are reset so that fuel injection to specific engine cylinders is inhibited. With this arrangement, since fuel injection is inhibited or reduced to an amount less than the conventional one upon deceleration, the economy of fuel consumption may be enhanced and as well the generation of smoke may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel injection method for a diesel engine, and particularly to a fuel injection method during deceleration.

[Background of the invention]

In a diesel engine, fuel is injected by correcting the basic fuel injection IT determined by the accelerator opening and the engine rotational speed based on intake air temperature, engine cooling water temperature, and the like. However, since fuel is injected based on the basic fuel injection amount even during deceleration, there are problems in that fuel efficiency deteriorates and harmful exhaust gas is emitted during deceleration. Further, in a diesel engine equipped with a venturi in the intake pipe, there is a problem in that the intake air is throttled by the venturi during deceleration, and white smoke is emitted because the ignitability of the fuel is significantly reduced.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel injection method for a diesel engine that improves fuel efficiency during deceleration, completely prevents the generation of white smoke, and improves exhaust gas characteristics. purpose.

[Summary of the invention]

The present invention has been made to achieve all of the above objects, and is a method for injecting fuel into diesel engines based on the basic fuel injection amount determined by the accelerator opening and the engine speed. It is characterized in that the fuel injection amount of the cylinder or a specific cylinder is set to a value less than the basic fuel injection amount. That is, during deceleration, an amount of fuel smaller than the basic fuel injection amount is injected into the cylinder, or fuel injection is stopped by setting the fuel injection amount to O, or an amount smaller than the basic fuel injection amount is injected into a specific cylinder during deceleration. In this example, fuel t is injected or fuel injection 'ji is set to O and fuel injection is stopped.

In the present invention, the following embodiment may be adopted in which the cylinder in which the fuel injection amount is reduced or the fuel injection is to be stopped is selected depending on the engine speed and the intake pipe pressure. The first aspect is that when decelerating and the engine speed is equal to or higher than a first predetermined value, the fuel injection lid of the gold cylinder is set to a value less than the basic fuel injection amount, and when the engine speed is decelerated and the engine speed is the j-th predetermined value. When the value exceeds the second predetermined value, which is less than the first predetermined value and is smaller than the first predetermined value, the fuel injection lid of the specified cylinder is set to a value less than the basic fuel injection amount, and the engine speed is reduced to the second predetermined value during deceleration. It is characterized in that when the amount is below a predetermined value, the fuel injection lid of the gold cylinder is set to a value based on the basic fuel injection amount. Further, in the second aspect, when decelerating and the engine speed is equal to or higher than the first predetermined value, the fuel injection amount of all cylinders is set to a value less than the basic fuel injection amount; D: When the value exceeds a second predetermined value that is less than a predetermined value and is p smaller than the first predetermined value, and the intake pipe pressure is below the predetermined value, the fuel injection amount of the specified cylinder is set to a value less than the basic fuel injection amount, and deceleration is performed. When the engine speed is less than the first predetermined value and exceeds the second predetermined value, which is smaller than the first predetermined value, and the intake pipe pressure exceeds the predetermined value, and the engine speed is less than or equal to the second predetermined value. It is characterized in that the fuel injection amount of all cylinders is set to a value based on the basic fuel injection amount when . Values less than 0 include 0,
Therefore, there is a cost involved when stopping fuel injection.

〔Effect of the invention〕

As explained above, according to the present invention, fuel injection is stopped or reduced compared to the conventional method during deceleration, so that the effect of improving fuel efficiency during deceleration and preventing the generation of white smoke can be obtained. .

[Funny example of invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A diesel engine to which the present invention is applied will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a diesel engine equipped with an electrified G-pill distributed fuel injection pump. An electromagnetic spill distribution type fuel injection pump is equipped with a solenoid valve in a communication passage that communicates a high pressure chamber formed by the cylinder inner wall surface and the plunger tip surface with a low pressure chamber (pump chamber) inside the pump. By controlling on/off of the communication path tm, the communication path tm is opened and closed, and the fuel injection amount is controlled.

The fuel filtered by the filter is transferred to the drive shaft 2
A vane-type feed pump (900 shown expanded) 4 driven by the oil supply port 6 is guided to the pressure regulating pulp 8, and after the pressure is regulated by the pressure regulating valve 8, the pulp is fed into the pump housing 10. The pump chamber 12, which is a low pressure chamber, is filled with water. The fuel filling the pump chamber 12 lubricates the operating parts within the pump chamber 12, and at the same time is sent to the high pressure chamber 8 formed at the tip of the plunger 16 via the suction boat 14 metal. A portion of the fuel is also circulated back to the fuel tank through the overflow valve 20 to drain excess fuel and cool working parts.

Suction groups 22 of the same number as the number of cylinders are bored at the tip of the plunger 16, and a distribution boat 26 communicating with an axial boat 24 is bored in the radial direction of the plunger 16. Further, a cam plate 28 is fixed to the tail end of the plunger 16, and the same number of rollers 32 as the number of cylinders fitted into the roller ring 30 are in contact with the cam plate 28. This plunger 16 is inserted into the cylinder 34 from the tip side, and the tip surface of the plunger 16 and the cylinder 34 are inserted into the cylinder 34 from the tip side.
The inner wall surfaces of 4 form 18 high pressure chambers. The cylinder 34 is provided with the suction boat 14 and the same number of distribution passages 38 for each cylinder, which communicate with the delivery valve 36 from the inner surface of the cylinder. A solenoid valve 44 is attached to the pump housing 10 to open and close the communication path 40. This communication path 40 is connected to the high pressure chamber 1
8 and the pump chamber 12 are communicated with each other.

Further, when the solenoid valve 44Fi and the solenoid 46 are turned on, the valve body 42 is attracted and the communication passage 40 is communicated with each other, and when the solenoid is turned off, the valve body is protruded and the communication passage 40 is cut off.

The drive shaft 2 protrudes toward the pump chamber 12 and is connected to a cam plate 28 via a coupling. The cam plate 28 is fixed to the plunger 16 and is pressed against the roller 32 by a spring 50. Therefore, the cam plate 28 is rotated by the drive shaft 2, and the cam crest of the cam plate 28 is rotated by the roller 3 depending on the contact state between the roller 32 and the cam plate 28.
2, the granger 16 is reciprocated a number of times equal to the number of cylinders during one rotation.

At the bottom of the fuel injection pump, there is a hydraulic timer (900 type) that changes the phase of the drive shaft 2 and the cam plate 28 that drives the plunger 16 to change the fuel injection timing using changes in the fuel supply pressure. (shown in the figure) 52 is provided. According to this timer 52, the spring 5
4 pushes the timer piston 56 in the direction of injection delay, and as the engine speed increases, the oil supply pressure increases and the piston 56 is pushed against the elastic force of the spring 54, so the roller The ring 30 is rotated in a direction opposite to the direction of rotation of the injection pump, and the fuel injection timing is advanced in proportion to the oil pressure. The ignition timing is controlled by controlling the hydraulic pressure applied to the piston 56 by the electromagnetic valve 48 so that the fixed ignition timing coincides with a target ignition timing predetermined according to engine conditions.

A signal rotor 60 is fixed to the tip of the drive shaft 2 coaxially with the drive shaft, and a roller ring 30
A pickup 62 is mounted so as to face the surface of the signal rotor 60. The signal rotor 60 has a plurality of convex teeth arranged at predetermined angles (for example, 5625 degrees), and the convex teeth are cut out at intervals equal to the number of cylinders to form toothless portions. In other words, in the case of a 4-cylinder diesel engine, as shown in Figure 2, 5
．． A plurality of convex teeth 60α, 60β, .
a to 60d are formed. Therefore, when the signal rotor rotates Ef, the convex teeth approach and move away from the pickup, so that the pickup outputs a pulse signal as shown in FIG. 3 due to electromagnetic induction. The wide valley portion of this pulse signal acts as a reference position signal, and the other portion acts as a rotation angle signal. In addition, the pickup and the signal rotor are such that before the plunger 1 is moved forward in the direction in which the high pressure chamber is reduced, that is, before the grunger is lifted, one of the missing teeth approaches the pickup and the pickup sends a reference position signal. The relative position is determined so that the pulse signal is outputted, that is, the width of the trough of the pulse signal is widened.

Further, the pump housing 10 is additionally provided with a fuel arm cut pulp 64 which stops the fuel injection pipe by blocking the suction boat 141.

The delivery valve 64 is connected to a fuel injection valve 68 that is installed so as to protrude into a sub-combustion chamber of a diesel engine 66. A glow plug 70 and an ignition sensor 72 for detecting fuel ignition are attached to this sub-combustion chamber. Further, a throttle valve 88 is arranged in the intake passage, and a pet/turi 90 is configured including this throttle valve 88.

In addition, 74 is an accelerator sensor that detects the accelerator opening degree;
76 is a pressure sensor that detects the intake pipe pressure, 78 is a water temperature sensor that detects the engine cooling water temperature, 80 is a glow relay, and 92V'i is a vehicle speed sensor.

Further, 84 is a signal rotor which is fixed to the crankshaft and has a protrusion at the top dead center position of a specific cylinder; 86 is a top dead center sensor that outputs a top dead center signal as the protrusion passes; 9
4 is a shift position switch.

As shown in FIG. 4, the above-mentioned accelerator sensor 74 has a contactor 74A fixed to the shaft of the throttle valve 88 and rotates together with the throttle valve, and one end of which is grounded and the other end connected to a power source and is in contact with the contactor 74A. The resistor 74B is arranged to be in contact with the 74 children. This contact 74A is connected to the input port of the microcomputer 82. Further, the accelerator sensor 74 has one end connected to a power source and the other end connected to a microcomputer 82.
An idle switch 74C connected to the input port is provided. This idle switch 74C is turned on when the throttle valve is fully closed.

In addition to the above-described accelerator sensor 74, the microcomputer 82 is connected to a pickup 62, an ignition sensor 72, a pressure sensor 76, a water temperature sensor 78, a vehicle speed sensor 92, a shift position switch 94, and a top dead center sensor 86. Further, the output port of the microcomputer 82 is connected to the glow plug 70 via the glow relay 80t, and also to the solenoid 46 of the solenoid valve 44, the solenoid of the solenoid valve 48, and the solenoid of the fuel injection cut valve 64. . microcomputer 8
2 is composed of a CPU, RAM, ROM, AD converter, etc., and the AD converter sequentially converts signals from the accelerator sensor, pressure sensor, and water temperature sensor into digital signals according to instructions from the CPU. Also, microcomputer +
7) ROMK is the routine program explained below,
Basic fuel injection amount Q calculated from accelerator opening ACCP and engine speed NK. The fuel injection timing (hereinafter referred to as spill angle θ) determined by the fuel injection amount Q corrected by the engine cooling water temperature and the engine speed NE (hereinafter referred to as spill angle θ) is stored in advance.

Next, an example in which the second aspect of the present invention is applied will be described. In this embodiment, a four-cylinder diesel engine is controlled, and first, in step 100, it is determined whether or not the engine is decelerating. Whether or not deceleration is in progress is determined based on signals output from the idle switch 74C, vehicle speed sensor 92, and shift position switch 94. For example, deceleration occurs when the shift position is in the drive range, the vehicle speed is above a predetermined value, and the idle switch 74C is on. It is judged to be medium. When it is determined that the engine is decelerating, it is determined in step 102 whether or not the engine speed NE is less than a first predetermined value (for example, 1200 rPm).

When the engine speed NE is equal to or higher than the first predetermined value, in step 106, the gold cylinder injection permission flag F, %F4
Reset and prohibit fuel injection f: of the gold cylinder. On the other hand, when the engine speed NE is less than the first predetermined value, it is determined in step 104 whether the engine speed Ng exceeds a second predetermined value (for example, 800 rpm). If the engine speed NE exceeds the second predetermined value, in step 108, the injection permission flag FlsFat- for the first and fourth cylinders is set, and the injection permission flags F2, F3t- for the second and third cylinders are set. Reset and prohibit specific air charge injection. Then, when the engine speed NB is not decelerating and the engine speed NB is less than or equal to the second predetermined value, the injection permission flag F for the gold cylinder is determined at step 110.
Set I=F4 to permit fuel injection in the gold cylinder.

FIG. 6 shows a fuel injection amount control routine. First, in step 112, all cylinders to which all fuel should be injected are determined based on the top dead center signal output from the top dead center sensor 86. In the next step 114, it is determined whether the injection permission flag for the cylinder determined in step 112 has been reset, that is, whether fuel injection is prohibited. When the injection permission flag for the cylinder determined by the switch 112 has been reset, in step 116 the solenoid valve 44 is kept in the ON state to allow the communication passage 4o to communicate, and fuel injection is prohibited.

On the other hand, when the injection permission flag for the cylinder determined in step 112 is set, Stella 711+
1 engine speed NK and accelerator opening ACCP
Based on the fuel injection mQk calculation, step 1
At 20, the engine speed NE is determined from the spill angle map.
The spill angle θ corresponding to the fuel injection angle Q is calculated by interpolation.

In the next step 122, before the plunger lifts,
For example, at the time when the reference position signal is output, the solenoid valve is turned off to disconnect the communication path tS, and when the plunger is weighed by a rotation angle signal corresponding to the spill angle θ, the solenoid valve is turned on and the communication path is opened. Connect and perform fuel injection.

As a result of the above, fuel injection in all cylinders is stopped when the engine speed is equal to or higher than the first predetermined value during deceleration, and when the engine speed is between the first predetermined value and the second predetermined value during deceleration. Seventh, fuel injection in a specific cylinder is stopped.

As explained above, according to this embodiment, the high-pressure chamber and the low-pressure chamber are communicated with each other to prevent fuel pressure in the high-pressure chamber from becoming sluggish, thereby stopping fuel injection. Even if fuel leaks into the high pressure chamber, the furnace fuel injection can be reliably stopped. Note that if fuel injection is stopped by the fuel injection cut valve, there is a risk that when fuel leaks into the high pressure chamber, the fuel pressure will increase and the fuel will be injected.

Next, a cylinder control routine for fuel injection in an embodiment in which the third aspect of the present invention is applied will be explained based on FIG. 7. Note that in FIG. 7, parts corresponding to those in FIG. 5 are designated by the same reference numerals, and explanations thereof will be omitted. In this embodiment, since the cylinder in which fuel injection is to be stopped is selected using the intake pipe pressure, when it is determined in step 104 that the engine speed NE exceeds the second predetermined value, the intake pipe pressure pim is determined in step 124. It is determined whether or not exceeds a predetermined value (for example, 560 Hgaba). When the intake pipe pressure pIm exceeds a predetermined value, fuel injection in the cylinder is permitted in step 110, and when the intake pipe pressure p1m is below the predetermined value, fuel injection in the specific cylinder is prohibited in step 108, and the remaining cylinders are Allows fuel injection only for cylinders. In this embodiment as well, the fuel injection amount control routine shown in FIG. 6 can be used.

In this embodiment, fuel injection is completely stopped only when the intake pipe pressure is low, that is, only when white smoke is generated, so that white smoke and exhaust gas (HC) can be significantly reduced.

5 In addition, in the above example, the # of all cylinders or a specific cylinder is
! Although the example in which the fuel injection r is stopped has been described, instead of completely stopping the fuel injection, a smaller amount of fuel than the basic fuel injection amount may be injected to completely improve the fuel efficiency. In particular, when prohibiting fuel injection in a specific cylinder, the fuel injection amount for all cylinders is set to the basic fuel injection amount multiplied by the number of injection prohibited cylinders/the number of all cylinders. This is the same as prohibiting fuel injection. Furthermore, in the above description, the injection pump is equipped with a so-called normally closed type electromagnetic valve that opens the communication passage when energized and shuts off the communication passage when it is not energized. It can also be applied to injection pumps equipped with normally open type solenoid valves.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a diesel engine equipped with a microcomputer to which the present invention is applied, and Fig. 2 is a plan view showing details of the signal rotor in Fig. 1. Figure 3 is a diagram showing the complete waveform of the pulse signal output from the pickup, Figure 4 is a circuit diagram showing details of the accelerator sensor, Figure 5 is a flowchart showing the cylinder control routine for fuel injection, and Figure 6 is a diagram showing the fuel injection cylinder control routine. The flowchart showing the quantity control routine, and the seventh part is a flowchart showing another example of the cylinder control routine for fuel injection. 60...Signal rotor, 62...Pickup,
74... Accelerator sensor, 76... Intake pressure sensor,
82...Microcomputer. Agent U % Tatsuyuki (and 1 other person) @ 2 Figure IF 5 Figure 4 Figure 115 @ 6 Figure 7

Claims (1)

[Claims] (1) In a diesel engine fuel injection method that injects fuel based on the basic fuel injection amount determined by the accelerator opening degree and the engine speed, fuel injection in all cylinders or a specific cylinder during deceleration: tt basic fuel injection amount A fuel injection method for a diesel engine, characterized in that the injection value is less than or equal to: