JPS6060238A - Apparatus for controlling fuel injection timing of diesel engine - Google Patents

Abstract

PURPOSE:To reduce emission of Diesel particulates and to increase the engine output at the time of accelerating an engine, by providing an injection timing determining means which operates a fuel injection timing varying means according to the outputs of an acceleration detecting means and a load detecting means. CONSTITUTION:A fuel injection pump 30 is provided with a fuel injection timing varying means 34. A correction-value calculating circuit 103 functions to increase a correction value for advancing the fuel injection timing at the time of low-load operation of an engine and to decrease the same at the time of high-load operation of the engine. The duty ratio is determined at a duty-ratio controlling circuit 104 on the basis of the corrected injection timing, and the fuel injection timing is controlled through duty control of an ON-OFF valve 42. With such an arrangement, it is enabled to reduce emission of Diesel particulates and to increase the engine output at the time of accelerating the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection timing control device for a diesel engine.

(Prior art) It is generally known that in diesel engines, particulates contained in exhaust gas include a large amount of HC in the low load range, and as the load range increases, IIc decreases and smoke (C) increases. It is being In addition, the fuel injection timing of the fuel injection pump has a large effect on the HC and smoke amount, and if the fuel injection timing is advanced, I-I
It is also known that while C decreases, smoke decreases with retard angle shift.

By the way, during acceleration, there is a demand for advancing the fuel injection timing in order to improve output, but doing so will increase smoke in the high load range, and conversely, if the advance amount is reduced, I-I in low load range
There is a problem that C increases.

Incidentally, as prior art, Utility Model Application No. 67-//, 20g/
A distribution type fuel injection pump that controls timing according to the load is known, as shown in No.

(Objective of the Invention) The present invention improves output during acceleration, and can reduce I-I C in exhaust gas in a low load range and smoke in exhaust gas in a high load range. An object of the present invention is to provide a fuel injection timing control device for a diesel engine.

(Structure of the Invention) In order to achieve the above-mentioned object, the present invention includes a fuel injection timing variable means provided in a fuel injection pump, an acceleration detection means for detecting the acceleration state of the engine, and a detection means for detecting the load state of the engine. The fuel injection timing is adjusted according to the output of the load detecting means and the rain detecting means so that during acceleration, the corrected advance amount is large in the low load range with respect to the reference timing, and the corrected advance amount is small in the high load range. It is characterized by comprising an injection timing setting means for operating the variable means. In other words, during acceleration, the fuel injection timing is advanced to improve output, but in the low load range, the correction advance amount is increased to increase the fuel injection timing compared to the standard timing.
While trying to reduce C, the amount of correction advance angle is reduced in a high load range to reduce smoke (see Figure 3).

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2, 1 is an indirect injection type double cylinder diesel engine, 2 is a combustion chamber of each cylinder 6,
is an intake passage, which includes a main intake passage 5 and two branch intake passages 6 that branch from the main intake passage 5 and lead to the combustion chamber 2 of each cylinder 6.
Each intake passage 6 is provided with an air heater 7 for heating intake air.

Reference numeral 8 denotes an intake throttle valve, which is controlled to open and close by a diaphragm device 9. In the diaphragm device 9, a casing 9a is connected to a first chamber 9c and a second chamber 9 by a diaphragm 9b.
It is divided into d and d. Spring 9e is in the first chamber 9C.
A negative pressure passage 11 in which a negative pressure control solenoid valve 10 is interposed is connected. Further, the diaphragm 9b is linked to the intake throttle valve 8 via a link mechanism 9f extending toward the second chamber 9d. .

The intake throttle valve 8 is used, for example, in an area where the engine cooling water temperature (hereinafter simply referred to as water temperature) is 30 to 0°C, the engine load (hereinafter referred to as average effective pressure) is below / Kg/ca, and the engine rotation speed is below iooorpm. Then, the intake negative pressure is controlled so as to improve the heating efficiency of the air heater 7.

Reference numeral 12 denotes an exhaust gas recirculation passage (hereinafter referred to as an EGR passage), which connects the exhaust passage 1 and the intake passage 4 downstream of the intake throttle valve 8. A blocking wall 16 having a large diameter hole 14 and a small diameter hole 15 is interposed in the middle of the EGR passage 12, and first and second exhaust recirculation valves 1 open and close both holes 14.15 of the blocking wall 16.
7.18 (hereinafter referred to as EGR valve) is installed. Each EGR valve '17.18 has a casing 17a, 18a connected to a diaphragm 17b, 1sb, and a first chamber 17C, 18C.
and a second chamber 17d, 18d, a first chamber 17c,
Spring 17e, 18e is compressed to 18c, and a negative pressure passage 21.22 in which negative pressure control solenoid valve 19.20 is interposed is connected, and diaphragm 17b,
1 sb second chamber 17d.

A valve body 17 (J, 18g) that opens and closes the holes 14 and '15 is connected to the 18d side via rod members 17f and 18f.

Said first and second,! The EGR valves 17 and 18, together with the intake throttle valve 8, are used, for example, when the water temperature is 0 to 700°C, the engine load is below JK/cd, and the engine speed is 200 to 300°C.
rpm, and/or speed (in the case of a 6-speed car), and is controlled according to the engine load as follows.

I) When the engine load is 5-B/Cd...
...The first EGR valve 17 is closed, the second EGR valve 18 is open, and the intake throttle valve 8 is fully open.

11) The engine load is 4', ! ;-6Kg7
In the case of crri... the first EGR valve 17 is open, the second E-GR valve 18 is closed, and the intake throttle valve 8 is fully open.

111) Engine load is θ~q j Kg/al
In the case...The first EGR valve 17 is open, the second EGR valve 17 is open, and the second EGR valve 17 is open.
When the R valve 18 is closed, the opening degree of the intake throttle valve 8 is controlled.

1v) When the engine load is less than θKf / CrrL...The /EICR valve 17 is closed, the second EGR valve 18 is closed, and the intake throttle valve 8 is opened at a constant degree.

A fuel injection pump 60 has a timer piston 66 that slides within a cylinder 62 formed in a housing 61, and is equipped with a timer 64 as a fuel injection timing variable means for controlling fuel injection timing. The timer piston 66 is connected to a roller holder 66 via a swingable lever 65. In addition, a first hydraulic chamber 38 in which a spring filter 7 is compressed on one side of the cylinder 32 with the timer piston 6 in between, and on which fuel pressure on the suction side of a feed pump (not shown) acts, is located on the other side. A second hydraulic chamber 41 to which the fuel pressure of the pump chamber 40 acts is formed through a pressure passage 69 provided in the timer piston 66. The first hydraulic chamber 38 and the second hydraulic chamber 41 are
They are connected through a connection path 4 in which an on-off valve 42 is duty-controlled by a control unit 1-60, which will be described later.

Therefore, basically, the position of the timer piston 66 is determined by the differential pressure between the first hydraulic chamber 38 and the first hydraulic chamber 38, that is, the fuel pressure according to the engine speed, and the elastic force of the spring 67, that is, the position of the lever 65. The inner circumferential direction position of the roller boulder 36 is determined through the , and the injection timing is determined by accumulating this information, but by controlling the duty of the opening/closing valve 42, it is possible to adjust the differential pressure, thereby correcting the injection timing. will be held.

50 is an intake pressure sensor that is disposed in the intake passage 4 downstream of the intake throttle valve 8 and detects the intake pressure; 51 is a water temperature sensor that detects the engine cooling water temperature; and 52 is a sensor that detects the shift position of a shift lever (not shown). J speed switch, 5'3. , '54 are a load sensor (load detection means) and a rotational speed sensor which are respectively provided in the fuel injection pump RO and detect the engine load and rotational speed, and 55 is a position sensor which detects the position of the timer piston 36.

60 is a control unit for the operation of the engine 1, which includes an air heater 7 and negative pressure control solenoid valves 10, 19, 20.
, intake pressure sensor 50, water temperature sensor 51, j speed switch 5
2. It is electrically linked to the load sensor 55, the rotation speed sensor 54, the timer 64 of the fuel injection pump filter 0, and the position sensor 55, and functions as timing setting means.

In addition, the fuel injection pump filter 0 is connected to the control unit 6.
0, the advance angle is controlled as follows.

1) Water temperature below 30℃, engine load below θKg/crd, engine speed below -〇〇Orpm, and intake temperature 7
In the area below 6℃, the advance angle is controlled according to the water temperature, rotation speed, and intake air temperature.

11) In each water temperature range of 30~0℃ and 0~/θo℃, the engine load is less than 9/crl, the engine speed is 20θ~3θ00 rpm, and the intake 't=/.

In the range of ℃ or higher and/or ~g speed (for 6-speed cars), the advance angle is controlled according to the load and rotation speed.

111) In areas other than the above i) and ii), advance angle control is performed according to the engine speed.

As shown in detail in FIG. 2, the control unit 6o determines a reference fuel injection timing (hereinafter referred to as reference timing) based on a load signal from a load sensor 56 and a rotation signal from a rotational speed sensor 54 in a timing calculation circuit 101. On the other hand, the acceleration detection circuit 102 determines whether or not it is acceleration based on the rotation speed signal, and in the case of acceleration, calculates the correction advance amount with respect to the reference timing according to the degree of acceleration. Calculated in circuit 10 (the corrected advance amount is large in the low load range (and small in the high load range).The reference timing is corrected, and the duty ratio control circuit 104 is calculated based on the corrected injection timing. A duty ratio is set at , and the on-off valve 42 is duty-controlled according to the duty ratio to determine the position of the timer piston 63 and control the fuel injection timing.

The acceleration detection circuit 102 includes a differentiation circuit 105 that calculates acceleration by differentiating the rotation signal, a first comparison circuit 106 that compares the acceleration with a set value to detect sudden acceleration, and a first comparison circuit 106 that detects slow acceleration. 2 comparison circuit 107.

A signal from the J-speed switch 52 (3° speed signal) is input to the correction amount calculation circuit 106 as a cancel signal.

A timing detection circuit 108 detects the actual injection timing based on the position signal of the timer piston 66 from the position sensor 55, and a correction signal is inputted to the duty ratio control circuit 104 based on the result.

Further, the change rate detection circuit 109 detects the change rate of the engine load based on the load signal, and the change rate is (minus).
If the side is greater than a predetermined value, it is determined that a gear change has occurred.
However, in the case of a gear change, the gear change correction circuit 110 adjusts the time during which the gear change is being performed.
The duty ratio is fixed.

Next, the control operation of the control unit 6o is as follows.
This will be explained along with FIGS. 3 and 3.

First, a rotation signal is input from the rotation speed sensor 54 in step S1, a load signal is input from the load sensor 53 in step S2, and a control map (see FIG. 7) is input in step S3 according to the engine rotation speed and engine load. ) and store the reference timing.

The rotation signal is differentiated in step S4, and based on the result, it is determined in step S5 whether or not there is an acceleration. If YES, the process moves to step S6, while if NO, the process proceeds to step S6.
Return to 1.

In step S6, the /
It is determined whether or not the speed is . In step S7, it is determined whether or not there is sudden acceleration.
In the case of S, it is determined in step S9 that the acceleration is advanced or medium, whereas in the case of No, that is, in the case of slow acceleration, it is determined that the acceleration is advanced or small in step S1o.

Next, load correction is performed in steps.
In the high load range, the correction is made to the retard side, that is, the amount of correction advance is small, and in the low load area, it is corrected to the advance side, that is, the amount of correction advance is increased (see Figure 2).

Based on the result of step Si1, the fuel injection timing is calculated in step "+2," the load signal is differentiated in step S13 to calculate the load change rate, and the load change rate is determined to be less than or equal to a predetermined value on the - (minus) side in step S14. Then, in step Si4, YE is determined.
In the case of S, it is determined that a gear change has not been performed, so in step S15 duty control is performed so that the injection timing is the same as that calculated in step S12.
Then, return to step S1 and repeat this process.

Further, if No in step S14, it is determined that a gear change is being performed, so the duty ratio is fixed in step S16, and it is determined in step S17 whether a certain period of time has elapsed. , in the case of No, the process returns to step "14" and is repeated. On the other hand, in the case of YES, it is determined that the gear change has been completed, so the process returns to step S1.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to improve the output during acceleration, and moreover, the amount of correction advance with respect to the reference timing is increased in the low load range to reduce HC. By reducing the amount of carbon (C) in the high load range, it is possible to reduce particulates during acceleration.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention; FIG. 1 is an overall configuration diagram of a fuel injection dumming control device for a diesel engine, FIG. 2 is a block diagram showing the configuration of a control unit, and FIGS. FIG. 5 is a diagram showing the relationship among fuel injection timing, engine load, and engine speed, and FIG. 3 is a flowchart showing the flow of processing by the control unit. 1...Diesel engine, RO...
Fuel injection pump, Roro... Timer piston,
ro4...timer, 56...load sensor, 54...rotation speed sensor, 60...
Control unit engine engine rotation speed end 1 OA//cm- Fig. 4 Engine rotation speed limit

Claims (1)

[Claims] (1) The fuel injection timing variable means provided in the fuel injection pump, the acceleration detection means for detecting the acceleration state of the engine, the load detection means for detecting the load state of the engine, and the rain detection means according to the output thereof. and injection timing setting means for operating the fuel injection timing variable means such that during acceleration, the corrected advance amount is large with respect to the reference timing in a low load area, and is small in a high load area. A diesel engine fuel injection timing control device featuring: