JPS5872626A - Detecting method of injection timing - Google Patents

Abstract

PURPOSE:To correctly detect injection timing, by obtaining a specific delay time from rotary speed of an engine and correcting the injection timing at the time fuel pressure in a fuel injection pump reaches a prescribed level. CONSTITUTION:The second pressure chamber 6 is provided togehter with the first pressure chamber 4 in a shaft 1 of a fuel injection pump, connected to a connection port 22 of a barrel 21 by providing an output port 19 and delivery port 20, and communicated to a combustion chamber (not shown in the drawing) via a delivery valve (not shown in the drawing) and the like. While a pressure detector 101 and rotary speed sensor 102 are mounted respectively in the pressure chamber 6 and injection pump, and their signal is input to a correcting circuit 103. Then time T1, at which pressure in the pressure chamber 6 is equalized to the valve opening pressure, is detected by a signal of the detector 101, and time delay tau, by which fuel from the pressure chamber 6 is injected to the combustion chamber, is detected by a signal of the sensor 102, thus injection timing can be substantially corrected to the timing T1+tau by the circuit 103.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection timing detection method, and particularly relates to a method for detecting injection timing, in which high-pressure fuel pressurized by a fuel injection pump driven by an internal combustion engine and working in synchronization with the internal combustion engine is injected from a fuel injection valve. The present invention relates to an injection timing detection method suitable for detecting injection timing.

Conventionally, when injecting fuel using a mechanical fuel injection pump, control was not performed to detect the fuel injection timing and feed it back, but instead the injection timing was set almost proportionally to the rotation speed of the injection pump. I was making progress. This injection timing adjustment is simply a phase change adjustment inside the injection pump, and the injection timing in the internal combustion engine relies on matching after the injection pump is installed.

However, if exhaust gas regulations become stricter in the future, more accurate injection timing control will be required, and it is clear that the conventional method will not be able to obtain accurate injection timing and will cause problems in response. Furthermore, as the entire injection pump becomes more electronic, more accurate detection of injection timing will become essential.

The present invention has been made in view of the above, and an object thereof is to provide an injection timing detection method that can accurately detect injection timing.

A feature of the present invention is that a fuel pressure detector detects the time when the pressure of high-pressure fuel pressurized by the fuel injection pump opens the fuel injection valve and reaches a nominal pressure, and the rotational speed of the fuel injection pump is detected by a fuel pressure detector. The fuel injection pump at that time detects the time delay until the high pressure fuel reaches the fuel injection valve via the high pressure pipe and opens the fuel injection valve at the time when the pressure detected by the pressure detector is reached. is corrected using the rotational speed of , and the injection timing at which high-pressure fuel is injected from the fuel injection valve is detected.

An embodiment of the method of the present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a sectional view showing an embodiment of a fuel injection pump equipped with injection timing detection means for explaining an embodiment of the injection timing detection method of the present invention. In FIG. 1, 1 is a shaft, 2 is a plunger provided in the shaft 1, 3 is a compression cam, 4 and 6 are first pressure chambers provided in the shaft 1, respectively, second pressure chambers 5 and 7 are shuttles, and 9 is a roller, 10 is a body, 11.12 is a radiation port, 13.14 is a sleeve 18
15 is an injection timing control solenoid valve, 16 is an injection amount control solenoid valve, and the fuel is supplied from the supply port 17 to the stain solenoid valve 15.
．． 16. Each of the solenoid valves 15 and 16 measures fuel using a valve opening pulse from the valve drive circuit 100, and controls the shaft 1.
The first of these. Send the measured amount of fuel to the second pressure chamber 4°6. The fuel passage is formed by fixed passages 13, 14 provided in the sleeve 18 and radiation ports 11, 12 of the same number as the number of cylinders provided in the shaft 1, which open and close as the shaft 1 rotates.

Further, the compression cam 3 attached to the body 10 is an inner cam, and the inner periphery is provided with protrusions of the same number as the number of cylinders. After supplying fuel to the respective pressure chambers 4 and 6, when the shaft 1 is driven and rotated by an internal combustion engine (not shown), the roller 9 starts to come into contact with the protrusion of the compression cam 3, and the plunger 2 is pushed toward the center. As a result, high pressure is generated inside the first pressure chamber 4. At this time, the fixed passage 13 and the radiation port 1
1 is in a closed state.

The high pressure generated in the first pressure chamber 4 pushes the shuttle 5 to the right, making the fuel in the second pressure chamber 6 high pressure. At this time as well, the fixed passage 14 and the radiation port 12 are closed. At the same time, one output port 19 provided on the shaft 1 and the sleeve 1
The same number of discharge ports 20 as the number of cylinders provided in 8 are in an open state. Therefore, the high pressure fuel in the second pressure chamber 6 is
A delivery nozzle (not shown), a high pressure pipe, which is attached to the connection port 22 of the barrel 21 from the output port 19 and the discharge port 20,
The fuel is injected into the combustion chamber of the internal combustion engine via the fuel injection valve.

If the injection state further progresses and the shuttle 5 moves to the right, the left end surface of the shuttle 5 will be connected to the relief opening 23 provided in the shaft 1.
and the first pressure chamber 4 are made to flow together.

At this time, a passage is formed between the fixed relief port 24 provided in the sleeve 18 and the second fixed relief port 25 provided in the barrel 21, and the high pressure fuel in the first pressure chamber 4 is released to the low pressure side, so that fuel injection is performed. finish.

Relief port 23 of shaft 1 and fixed relief port 2 of sleeve 18
4 is opened and closed by rotation of the shaft 1.

Here, the injection timing can be adjusted by the amount of fuel supplied from the injection timing control solenoid valve 15 to the first pressure chamber 4. If there is a large amount of feed (injection timing control solenoid valve 15 is opened), if the width of each loop is long), as shown in FIG. 2, which is a cross-sectional view taken along line A-A in FIG. , the contact between the protrusion of the compression cam 3 and the row 29 occurs at an early stage, resulting in an advance angle operation. On the other hand, if the supply amount is small (if the width of the valve opening pulse to the injection timing control solenoid valve 15 is short), the convex part of the compression cam 3 and the row 29 will come into contact at a late stage, resulting in a retarded operation. Therefore, injection timing can be easily controlled.

Further, the injection amount can be controlled depending on the amount of fuel supplied from the injection amount control solenoid valve 16 to the second pressure chamber 6.

By the way, in the above-described operation, the fuel discharged from the second pressure chamber 6 is delivered to the delivery pulp, high pressure pipe,
There is a time delay before the fuel is injected into the combustion chamber of the internal combustion engine via the fuel injection valve.

At this time, the rotation speed and the high-pressure pipe length are dominant contributors to the time delay τ, and if the high-pressure pipe length is constant, the delay time caused by the high-pressure pipe length is a constant. Also, if the valve opening pressure P of the fuel injection valve is the same,
The valve opening pressure will be the same.

Therefore, if the time when the pressure in the second pressure chamber 6 rises and reaches the valve opening pressure P1 of the fuel injection valve is T1 (injection timing in the injection pump), fuel is actually injected into the combustion chamber of the internal combustion engine. The time at which this is performed is (T, +τ). This time (T, +τ) becomes the actual injection timing.

Therefore, in the embodiment of the present invention, the injection timing T in the injection pump is defined as the timing when the fuel pressure in the second pressure chamber 6 becomes equal to the valve opening pressure of the fuel injection valve. Detection is performed by a pressure detector 101 that utilizes the effect. Regarding the correction of the delay time τ mentioned above, the part that depends on the length of the high-pressure pipe will be a constant if the high-pressure pipe length is the same, so it is only necessary to correct the delay time that changes depending on the rotation speed at any time. , Therefore, the rotation sensor 102 is installed inside the injection pump, and the rotation sensor 1
The correction was made using the signal from 02. Reference numeral 103 denotes a correction circuit, which corrects the injection timing in the injection pump using the signal from the pressure detector 101 and the signal from the rotation sensor 102, and adjusts the actual injection timing of high-pressure fuel from the fuel injection valve. Detects the injection timing.

In addition, in the embodiment described above, the actual injection timing and the optimum injection timing are compared in the valve drive circuit 100.
The amount of fuel supplied to the first pressure chamber 4 is increased or decreased, thereby enabling accurate and responsive injection timing control.

As described above, according to the present invention, it is possible to accurately detect the timing of fuel injection into the combustion chamber of an internal combustion engine, and it is possible to improve the controllability of the injection timing.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a fuel injection pump equipped with injection timing detection means for explaining an embodiment of the injection timing detection method of the present invention, and FIG. 2 is a cross-sectional view taken along line A-A in FIG. It is a line cross-sectional view.

Claims (1)

[Claims] 1. In a fuel injection pump that is driven by an internal combustion engine and operates in synchronization with the internal combustion engine, a fuel pressure detector detects when the fuel pressure generated within the fuel injection pump reaches a pressure that opens the fuel injection valve. The rotational speed of the internal combustion engine is determined by the time delay until the high-pressure fuel reaches the fuel injection valve via the high-pressure pipe and opens the fuel injection valve at the timing when the pressure detected by the detector is reached. 1. An injection timing detection method, comprising detecting and correcting the rotational speed based on the rotational speed at that time to detect an injection timing at which high-pressure fuel is injected from the fuel injection valve.