JPS6123861A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To simplify constitution and cut cost by controlling the valve closing timing and valve opening timing by using only one solenoid valve. CONSTITUTION:When a solenoid valve 15 is closed at a certain position midway in a suction cycle, the supply of fuel into the first pressure chamber 10 is suspended, and since the second pressure chamber 11 always communicates to a passage 23, a timing plunger 9 shifts leftward by the rest stroke of a compression plunger 5. When the suction cycle of the compression plunger 5 is completed, the timing plunger 9 stops shift. Therefore, fuel injection starting timing can be controlled by controlling the valve closing timing of the solenoid valve 15. Further, in the compression cycle of the compression plunger 5, fuel injection completion time, namely the injection amount can be controlled by controlling the valve opening timing of the solenoid valve 15.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection device that supplies fuel to an engine, and relates to a fuel injection pump suitable for electronically controlling the amount and timing of fuel injection. It is.

(Prior art) Conventionally, as a fuel injection pump, for example,
56660, the pressure chamber that receives compression as the pump rotates is divided by a free piston, one pressure chamber is supplied with fuel according to the injection amount, and the other pressure chamber is supplied with fuel according to the injection timing. a configuration for supplying fuel relating to;
That is, a first pressurizing chamber that communicates with the first opening/closing means for liquid suction and a pressurizing mechanism, a second pressurizing chamber that communicates with the second opening/closing means for liquid suction and a discharge passage for discharging liquid, and a free piston disposed between the first pressurizing chamber and the second pressurizing chamber and capable of transmitting hydraulic pressure between the pressurizing chambers;
The pressurizing mechanism alternately generates a compression engine that restrictively pressurizes and compresses in accordance with rotation, and an intake engine that allows fuel intake in a non-restrictive manner when fuel is supplied to at least one of the pressurizing chambers. The first pressurizing chamber and the second pressurizing chamber are configured as follows.
2. Description of the Related Art There is a known configuration of a fuel injection pump that controls the timing and amount of liquid discharged by controlling the amount of liquid sucked into a pressurizing chamber.

(Problems to be Solved by the Invention) However, this configuration requires two opening/closing means, the first opening/closing means and the second opening/closing means, to control the amount of fuel supplied, resulting in a complicated structure. It also has the disadvantage of being expensive.

(Objective of the Invention) An object of the present invention is to eliminate the drawbacks of the conventionally known fuel injection pumps and to provide a fuel injection pump that has a simple structure, is inexpensive, and can be electronically controlled.

(Means for Solving the Problems) The present invention provides a timing plunger to divide the pressure that is compressed as the pump rotates into two parts, and supplies fuel according to the injection amount to one first pressure chamber and the other. The fuel injection pump is similar to the conventional fuel injection pump in that it supplies fuel related to the injection timing to the second pressure chamber of the pump, but the two fuel supply amounts are controlled by one opening/closing means. Features.

That is, the intake fuel passages (13, 14) are connected to the first pressure chamber (10).
, 16) and the intake fuel passages (13, 14).
,,16), one opening/closing means (15) is provided in the middle of the fuel passage (19, 22,' 23) in the second pressure chamber (11).
and selectively discharge fuel passage (1B) to the first pressure chamber (10).

24 and 25) were configured to communicate with each other.

(Function) When the compression chamber (100) is in the suction stroke, the opening/closing means (1
5) Open the valve and first suck fuel into the first pressure chamber (10) through the suction fuel passage (13, 14, 16), and then close the opening/closing means (15) to open the timing plunger. (9) moves, and fuel that determines the injection start timing is sucked into the second pressure chamber (11). Compression chamber (100)
When the is in the discharge stroke, the opening/closing means (15
) is closed, and the second pressure chamber (11) is connected to the fuel passage (
19°22.23), the timing plunger (9) moves, and when the movement stops, the fuel pressure in the first pressure chamber (10) increases and the discharge fuel passage is selectively communicated. (1B, 24.25> and fuel injection is started. Here, when the opening/closing means (15) opens the valve, the fuel in the first pressure chamber (10) is discharged from the intake fuel passage (13,
14, 16), the fuel pressure in the first pressure chamber (10) decreases, and fuel injection ends.

(Embodiment) FIGS. 1 to 3 relate to an embodiment of the present invention. FIG. 1 is a longitudinal cross-sectional view of the embodiment, and FIG.
A cross-sectional view taken along the line and FIG. 3 each show an operation characteristic diagram showing the correspondence between a reference signal for a change in cam angle, a change in cam lift, and an opening/closing of a solenoid valve.

First, the structure will be explained.

In FIG. 1, at least one pair of pumping plungers 5 fitted into radial holes of a shaft 1 rotating in synchronization with the engine, a roller shoe 3 housed on the outside of each plunger, and a roller 2 are provided, and the shaft Rotates with 1.

A roller ring 4 having a cam shape on the inner surface is attached to a housing 6 on the outer periphery of the roller 2, as shown in FIG. The shaft 1 has a bearing 35 fitted into the housing 6.
and the inner periphery of a bushing 8 attached to the housing 7 to perform rotational movement.

Inside the shaft 1, there is a timing plunger 9 that is slidably fitted into a hole in the central axis direction of the shaft 1, and communicates with a pressure chamber 100 that is compressed by the pressure-feeding plunger 5 and the compression pressure 100, and also communicates with the timing plunger 9. Plunger 9
A first pressure chamber 10 is formed adjacent to the end face of the timing plunger 9, and a first pressure chamber 10 is formed between the timing plunger 9 and a plug 12 that is oil-tightly screwed into the right end of the axial hole to prevent fuel leakage. Two pressure chambers 11 are provided.

The first pressure chamber 10 includes an intake fuel passage, i.e., a passage 13 provided in the shaft 8, and a passage 13 provided in the bush 8.
4 is always in communication. On the other hand, as the shaft 1 rotates, the passage 18 provided in the shaft 1 and the passage 24 provided in the bush 8 are selectively brought into communication to form a discharge fuel passage. Further, the passage 24 communicates with a passage 25 provided in the housing 7. The housing 7 has a passage 25
A valve holder 27 for attaching a delivery pipe (not shown) is attached. Valve holder 2
7 has a built-in suction valve (not shown).

The second pressure chamber 11 includes a passage 19 provided in the shaft 1;
It is constantly in communication with a fuel passage consisting of a passage 22 provided in the bushing 8 and a passage 23 provided in the housing 7.

A pulser 20 is fixed to the shaft 1, and its rotational speed is detected by a rotational speed sensor 21.

The housing 7 is provided with a solenoid valve 15 which is an opening/closing means for controlling the suction and discharge timing of fuel sucked into and discharged into the first pressure chamber IO.
It communicates with a passage 14 provided in the housing 7 and a passage 16 provided in the housing 7 .

In FIG. 2, as shown, the fuel injection pump has a suction period θ during which fuel is sucked by clockwise rotation of the shaft 1.
2 and a pumping period θ1 during which compressed discharge is performed.

In addition, since FIG. 2 shows a fuel injection pump for a four-cylinder engine as an example, the structure has four cam shapes corresponding to each cylinder at four equally divided positions on the inner circumference of the rolling 4.

Next, the operation will be explained.

In FIG. 1, during the suction stroke of the pressure-feeding plunger 5, fuel passes through a fuel tank, a fuel filter sedimenter, and a pressure regulator (not shown);
from the solenoid valve 15, the passage 14, and the passage 13 to the first pressure chamber 10, and the other from the passage 23 to the passage 2.
2 and passage 19 to the second pressure chamber 11 .

During the suction stroke of the pressure-feeding plunger 5, the electromagnetic valve 15 is open, and the movement stroke of the pressure-feeding plunger 5 increases the amount of fuel filled in the first pressure chamber 10.

On the other hand, when the solenoid valve 15 is opened in the middle of the suction stroke, the movement stroke of the pressure-feeding plunger 5 causes the first pressure chamber 1 to open.
0 is lower than the pressure in the second pressure chamber 11, the timing plunger 9 moves to the left in the figure, and the amount of fuel filling the second pressure chamber 11 increases.

On the other hand, during the pressure-feeding stroke of the pressure-feeding plunger 5, the solenoid valve 15 is closed, and the pressure in the first pressure chamber 10 increases due to the movement stroke of the pressure-feeding plunger 5, while the pressure in the second pressure chamber 11 is constantly increased. Since it communicates with the passage 23, the timing plunger 9 moves to the right in the figure. While the timing plunger 9 is moving, the pressure in the first pressure chamber 10 does not rise that much, but when the timing plunger 9 comes into contact with the plug 12 and stops moving, the pressure in the first pressure chamber IO increases. becomes larger, and the fuel in the first pressure chamber 10 passes through the passage 181, the passage 241, the passage 25, the valve holder 27, the delivery pipe (not shown), and starts being injected from a nozzle (not shown).

During the pressure-feeding stroke of the pressure-feeding plunger 5, the solenoid valve 1
When the valve 5 is opened, the pressure in the first pressure chamber 10 decreases rapidly, and fuel injection ends.

As can be understood from the above explanation, the injection of the fuel in the first pressure chamber 10 is delayed by the movement stroke of the timing plunger 9 from the start of pressure feeding, and the fuel injection start timing is the same as that of the timing plunger 9 at the start of pressure feeding. It will depend on the position of.

Therefore, by controlling the position of the timing plunger 9, the injection start timing can be controlled.

A method of controlling the injection start timing will be explained.

In FIG. 1, during the suction stroke of the pressure-feeding plunger 5, the solenoid valve 15 is open, and the movement stroke of the pressure-feeding plunger 5 causes the passage 16, the solenoid valve 15, the passage 14,
A passage 13 is provided, and fuel is supplied to the first pressure chamber 10.

Here, as shown in FIG. 3, when the solenoid valve 15 is closed at position 2 in the figure during the suction stroke, the fuel supply to the first pressure chamber 10 is stopped, while the second pressure Room 1
1 is always in communication with the passage 23, the remaining movement stroke of the pressure-feeding plunger 5 causes the timing plunger 9 to move to the left in the figure. Then, when the suction stroke of the pressure-feeding plunger 5 is completed, the timing plunger 9 stops moving.

In this way, by controlling the closing timing of the solenoid valve 15, the position of the timing plunger 9 can be controlled. Therefore, by controlling the closing timing of the electromagnetic valve 15, the fuel injection start timing can be controlled.

The timing for closing the solenoid valve 15 is determined by using the output of a reference position sensor (not shown) that detects the position of the piston or cam of the engine or the position of the cam of the injection pump as a reference signal, and plotting the time t2 from this reference signal. The calculation is performed by a computer (not shown), and based on the calculation result, a valve closing signal is given to the solenoid valve 15 to close the valve.

If the closing timing of the electromagnetic valve 15 is advanced and the valve is closed at the position 2a in FIG. 3, the amount of movement of the timing plunger 9 to the left in the figure increases and the fuel injection start timing is delayed.

On the other hand, if the valve closing timing is delayed and the valve is closed at the position 2b in FIG. 3, the amount of movement of the timing plunger 9 to the left in the figure will be reduced and the fuel injection start timing will be advanced.

Next, a method of controlling the fuel injection end timing, that is, the fuel injection amount (or) will be explained.

As shown in FIG. 1, when the solenoid valve 15 is closed during the pressure-feeding stroke of the pressure-feeding plunger 5, the timing plunger 9 comes into contact with the plug 12 due to the movement stroke of the pressure-feeding plunger 5, and after the movement stops. , the fuel in the first pressure chamber 10 flows through passages 18, 242, 25. The liquid passes through the valve holder 27, passes through a delivery pipe (not shown), and is injected from a nozzle (not shown).

After that, as shown in FIG.
When the solenoid valve 15 is opened at the position, the first pressure chamber 10
The fuel in the passage 13. Passage 14, solenoid valve 15. Passage 1
6, the pressure in the first pressure chamber IO decreases,
Fuel injection ends.

If the opening timing of the electromagnetic valve 15 is advanced to open at position 1a, the end timing of fuel injection will be advanced, and as a result, the injection amount will be reduced.

Conversely, if the valve opening timing is delayed and the valve is opened at the position 1b, the end timing of fuel injection will be delayed, and as a result, the injection amount will increase.

In this manner, by controlling the opening timing of the electromagnetic valve 15 during the pressure feeding stroke of the pressure feeding plunger 5, the fuel injection end timing, that is, the fuel injection amount can be controlled.

As shown in FIG. 3, the opening timing of the solenoid valve 15 is determined by calculating the time t1 from the reference signal by a computer (not shown) and giving a valve opening signal to the solenoid valve 15 based on the calculation result. Open the valve.

As described above, the closing timing of the solenoid valve 15 determines the movement of the timing plunger 9, that is, the timing to start fuel injection, and the opening/closing timing of the solenoid valve 15 determines the timing to end fuel injection. Therefore, by controlling the valve closing timing and valve opening timing of the electromagnetic valve 15, it is possible to appropriately control the fuel injection start timing from the pump and the fuel injection amount determined by the fuel injection start timing and end timing. .

In FIG. 3, the solenoid valve 15 has a closing timing 2 and an opening timing l.
If the fuel injection timing is advanced by changing the valve closing timing to 2b from the state where the valve is being driven, the fuel injection amount is kept constant by changing the valve opening timing to 1a and advancing the fuel injection end timing. It is also possible to start the fuel injection earlier.

In the embodiments described above, the opening/closing means is constituted by a seat valve type solenoid valve, but a spool valve type solenoid valve may also be used.

Further, in the above embodiment, the fuel compression mechanism was constructed using an inner cam system, but those skilled in the art will easily understand that it can be constructed using other compression systems, such as a face cam system or an outer cam system. . (Effects of the Invention) As described in detail above, according to the present invention, by controlling the closing timing and opening timing of only one solenoid valve, the injection timing and injection amount are controlled. This has the excellent effect of providing a fuel injection pump with a simple structure and low cost.

[Brief explanation of drawings]

1 to 3 relate to an embodiment of the present invention, FIG. 1 is a longitudinal sectional view of the embodiment, and FIG. 2 is a view taken along A--A in FIG.
A sectional view taken along line A and FIG. 3 each show an operation characteristic diagram showing the correspondence between a reference signal, a change in cam lift, and the opening of a solenoid valve with respect to a change in cam angle. 9... Timing plunger, 10... First pressure chamber, 11... Second pressure chamber, 13, 14.16... Intake fuel passage, 15... Solenoid valve forming valve opening means, 18 .2
4゜25.27...Discharge fuel passage, 19,22.23
...Fuel passage, 100...Compression chamber

Claims (1)

[Claims] A pressure chamber communicating with a compression chamber (100) that receives compression as the pump rotates is divided into two parts by a timing plunger (9) slidably fitted into the pressure chamber.
A first pressure chamber (10) communicating with the compression chamber (100) and the compression chamber (
In the fuel injection pump, a second pressure chamber (11) is formed that does not communicate with the first pressure chamber (10), and an intake fuel passage (13, 14, 16) communicates with the first pressure chamber (10). , 14, 16) is provided in the middle of the opening/closing means (15) to communicate the fuel passage (19, 22, 23) to the second pressure chamber (11) and to communicate the fuel passage (19, 22, 23) to the first pressure chamber (10). Discharge fuel passages (18, 2) that selectively communicate with each other
4, 25), the fuel injection start timing is determined by closing the opening/closing means (15), and the timing for starting fuel injection is determined by closing the opening/closing means (15).
5) A fuel injection pump characterized in that the fuel injection end timing is controlled by opening the valve.