JPS6128753A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To control the injection timing via the valve closing timing, control the injection quantity via the valve opening timing, simplify the structure, and reduce the cost by using only one solenoid valve to control the fuel quantity fed to individual pressure chambers. CONSTITUTION:When the closing timing of a solenoid valve 15 is accelerated, the fuel feed period to the second pressure chamber 11 is shortened, the fuel feed quantity is decreased, the shift stroke of a timing plunger 9 is shortened, and the injection timing is accelerated. That is, the injection timing can be controlled by controlling the closing timing of the solenoid valve 15. On the other hand, when the opening timing of the solenoid valve 15 is accelerated, the fuel injection is finished early, and the injection quantity is decreased. That is, the injection quantity can be controlled by controlling the opening timing of the solenoid valve 15 during the pressure-feed stroke of a pressure-feed plunger.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection device for supplying fuel to an engine, and relates to a fuel injection pump suitable for electronically controlling the fuel injection amount and fuel injection timing. be.

[Prior art]

Conventionally, as a fuel injection pump, for example, Japanese Patent Application Laid-open No. 5'7-
56660, the pressure chamber that receives compression as the pump rotates is divided into two parts by a free piston, one pressure chamber part is supplied with fuel according to the injection amount, and the other pressure chamber part is supplied with fuel according to the injection timing. The structure for supplying fuel according to 2 pressurizing chambers, and the first
The pressurizing mechanism includes a free piston arranged between a pressurizing chamber and the second pressurizing chamber and capable of transmitting liquid between the pressurizing chambers; The engine is configured to alternately generate an intake engine that allows fuel to flow in a non-restrictive manner when fuel is supplied to at least one of the pressurizing chambers, and the first pressurizing chamber and the second pressurizing chamber 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 chamber.

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, which has the disadvantage of making the structure complex and 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 is simple in structure, inexpensive, and capable of electronic control.

[Summary of the invention]

In the present invention, a timing plunger is provided to divide a pressure chamber that is compressed as the pump rotates into two parts, and one pressure chamber is supplied with fuel related to the injection amount, and the other pressure chamber is supplied with fuel related to the injection timing. The present invention is similar to the conventional fuel injection pump in this respect, but provides an injection pump in which the amount of fuel supplied to each pressure chamber is controlled by one solenoid valve.

To explain further, a first pressure chamber ('10) and a second pressure chamber (11) which are divided into two by a timing plunger (9) are provided, and a suction passage (45) is provided in the first pressure chamber (10).
, 46, 22) and the discharge passages (18, 24, 25), and a control passage (13) which communicates with the first pressure chamber (10) is provided. A fuel passage (17) is provided, a check valve (40) is provided that allows communication with the low pressure side, and a first pressure chamber (10) is provided.
) and the intake fuel passage (17) of the second pressure chamber (11).
4, 16), and one opening/closing means (15) is provided in the middle of this fuel passage.

[Effect]
(In the pump suction stroke, fuel is supplied to the first pressure chamber (10) from the suction passage (45, 46, 22) at a pressure P2, and the second pressure chamber (11) is supplied from the solenoid valve from the fuel passage (1G). (15), fuel pressure P via the intake fuel passage (17)
Supplied by I. Here, the relationship is set as Pl>P2. Also, in the pop-up stroke, the fuel passages (14, 16
) is in communication with the first pressure chamber (10) via the control passage (13), and the discharge passage (18, 24, 25) to the nozzle is also connected to the first pressure chamber (10). communicate with.

When the plunger (5) starts pumping, the timing plunger (9) moves to the right, and the fuel in the second pressure chamber (11) flows out to the low pressure side through the check valve (40). When the timing plunger (9) hits the check valve (40) and stops moving, the fuel pressure in the first pressure chamber (10) increases and injection from the nozzle begins via the discharge passage (18, 24, 25).

Therefore, the injection timing is determined by the timing plunger (
9), and the position is controlled at the timing when the solenoid valve (15) is closed after the fuel passage (14) and the intake fuel passage (17) communicate with each other.

The injection amount is controlled by the opening timing of the solenoid valve (15) during injection.

In this way, the fuel injection amount is controlled by opening the solenoid valve (15), which is one opening/closing means, and the solenoid valve (15) is opened.
The fuel injection timing is controlled by closing the valve 15).

〔Example〕

1 to 4 relate to an embodiment of the present invention, and FIG. 1 is a cross-sectional view of the embodiment during the fuel intake stroke, and FIG.
rI! J is a cross-sectional view in the fuel discharge stroke of the example, the third
This figure is a sectional view taken along the line A--A in FIG. 2, and FIG. 4 is an operating characteristic diagram showing the correspondence between the reference signal, the cam lift change, and the opening/closing of the electromagnetic valve with respect to the change in the cam angle.

First, the structure will be explained.

In FIG. 1, the engine rotates in synchronization with the engine.

At least one pair of pumping plungers 5 which fit into radial holes in the shaft 1 and a roller shoe 3 housed outside each plunger and a roller 2 are provided and rotate with the shaft 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 compression chamber 100 that is compressed by the pressure-feeding plunger 5. Plunger 9
A first pressure chamber 10 is formed adjacent to the end face of the axial hole, and a second pressure chamber 11 is formed between the check valve 40 and the timing plunger 9 arranged at the right end of the axial hole. .

The check valve 40 has a passage 41 communicating with the second pressure chamber 11;
It is comprised of a valve 42 that opens and closes the passage 41, a spring 43 that biases the valve 42, and a passage 44 that communicates with the low pressure side, allowing fuel to flow out to the low pressure side. However, valve 42
is set to open at a pressure lower than the opening pressure of an injection nozzle (not shown) attached to the engine.

The first pressure chamber 10 communicates with the same number of passages 45 as the number of engine cylinders provided in the shaft l, and during the fuel intake stroke, the first pressure chamber 10 communicates with passages 46 provided in the bush 8, - and! It selectively communicates with passages 22 and 23 provided in the housing 7 to form a suction passage.

Further, as shown in FIG. 2, the first pressure chamber 10 communicates with the same number of control passages 13 as the number of engine cylinders provided in the shaft 1, and during the fuel discharge stroke, the first pressure chamber 10 communicates with the control passages 13 provided in the shaft 1, and the fuel It selectively communicates with the passage 14 and a fuel passage 16 provided in the housing 7 .

The first pressure chamber 10 also communicates with one passage 18 provided in the shaft 1, and during the fuel discharge stroke, the first pressure chamber 10 communicates with the passage 24 of the bushings 8, which are arranged in the same number as the number of engine cylinders, and the passage 24 of the housing 7. It selectively communicates with one of the passages 25 to form a discharge passage.

The housing 7 is provided with a valve holder 27 that communicates with the passage 25 and is used to attach a delivery pipe (not shown).

In FIG. 1, the second pressure chamber 11 communicates with the same number of intake fuel passages 17 as the number of engine cylinders provided in the shaft 1, and during the fuel intake stroke, the second pressure chamber 11 communicates with the fuel intake passages 17 provided in the bush 8. selectively communicate with

A solenoid valve 15 is arranged in the housing 7 , and a fuel passage 14 provided in the bush 8 and the housing 7 are connected to each other.
The fuel passage 16 provided in the fuel passage 16 is communicated and cut off.

If the fuel pressure supplied from the passage 16 is P+, and the fuel pressure supplied from the passage 23 is P2, a pressure regulator (not shown) is disposed so that the relationship PI>P2 holds.

Further, the fuel pressure P1 is set to a lower value than the on-off valve of the check valve 40.

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

The space 5o in which the balsa 20 is housed communicates with the passage 44 of the check valve 40, and also communicates with the passage 22 provided in the housing 7 via a passage 51 provided in the bush 8.

As shown in FIG. 3, the fuel injection pump has a suction period θ2 in which fuel is sucked by clockwise rotation of the shaft 1, and a discharge period θ1 in which fuel is compressed and discharged.

In addition, since FIG. 3 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 low sill ring 4.

Next, the operation will be explained.

In the first FgJ, during the suction stroke of the pressure-feeding plunger 5, the passage 14 and the passage 17, and the passage 46 and the passage 45 communicate with each other.

The fuel passes through a fuel tank, a fuel filter, and a fuel tank (not shown), and a first pressure regulator (not shown), a passage 16, a solenoid valve 15 (opened), a passage 14, and a passage 17. The other one is supplied to the first pressure chamber 10 from the passage 23 through the passage 22, the passage 46, and the passage 45 via a second pressure regulator (not shown).

Since the fuel pressure supplied from the passage 16 is set higher than the fuel pressure supplied from the passage 23, the second pressure chamber 11
The pressure inside becomes higher than the pressure inside the first pressure chamber lo, the timing plunger 9 moves to the left in the figure, and the fuel filling the second pressure chamber 11 increases.

On the other hand, in the pumping stroke of the pumping plunger 5, the passage 14, the passage 17, and the passage 4 are
6 and the passage 45 are cut off.

Further, as shown in FIG. 2, the passage 14 and the passage 13 and the passage 18 and the passage 24 communicate with each other.

As the pressure in the first pressure chamber 10 increases due to the movement stroke of the pressure-feeding plunger 5 (the solenoid valve 15 is closed), the timing plunger 9 moves to the right in the figure, and accordingly, the timing plunger 9 moves to the right in the figure. The pressure inside the pressure chamber 11 also increases.

When the pressure inside the second pressure chamber 11 rises above the opening pressure of the check valve 40, the valve 42 opens and the fuel inside the second pressure chamber 11 flows into the check valve 4 as the timing plunger 9 moves.
0 flows out through the passage 41 into the space 50.

Note that the opening pressure of the check valve 40 is set to be lower than the opening pressure of an injection nozzle (not shown) disposed in the engine, so while the timing plunger 9 is moving, the pressure inside the first pressure chamber 10 is The pressure is maintained at a level lower than the opening pressure of the injection nozzle.

When the timing plunger 9 comes into contact with the check valve 40 and ends its movement, the pressure inside the first pressure chamber 10 starts to rise further, and when it becomes higher than the opening pressure of the injection nozzle arranged in the engine, the pressure inside the first pressure chamber 10 starts to rise. Fuel is passageway 8, passageway 24,
The liquid is injected from an injection nozzle through a passage 25, a valve holder 27, and a delivery pipe (not shown).

During injection, when the solenoid valve 15 is opened, the high pressure fuel in the first pressure chamber 10 flows through the passage 13, passage 14,
(Since it escapes into the passage 16 through the electromagnetic valve 15, the pressure in the first pressure chamber 10 decreases and the injection ends.

As can be understood from the above explanation of operation, fuel injection from the injection nozzle is delayed from when the timing plunger 9 starts pumping until it comes into contact with the check valve 40, so the fuel injection timing control is based on the position of the timing plunger 9 at the start of pumping. ,
In other words, this becomes possible by controlling the amount of fuel supplied into the second pressure chamber 11.

A method of controlling fuel injection timing will be explained.

As shown in FIG. 1, during the suction stroke of the pressure-feeding plunger 5, fuel is supplied to the second pressure chamber 11 through the passage 1.
6, solenoid valve 15, passage 14, and passage 17 are supplied.

That is, by controlling the opening period of the electromagnetic valve 15, the amount of fuel supplied to the second pressure chamber 11 can be controlled.

In FIG. 4, 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 is used as a reference signal, and the time t2 from this reference signal is calculated by a computer (not shown). However, when a valve closing signal is given to the solenoid valve 15 based on the calculation result, the second pressure chamber 1
1 is supplied with fuel.

If the closing timing of the solenoid valve 15 is advanced to the timing t2a,
The fuel supply period to the second pressure chamber 11 is shortened, the amount of fuel supplied is reduced, the movement stroke of the timing plunger 9 is shortened, and the fuel injection timing is advanced.

On the other hand, if the valve closing timing is delayed and performed at the timing t2b, the fuel supply period will be extended and the fuel injection timing will be delayed.

As can be seen from the above description, by controlling the closing timing of the electromagnetic valve 15, the fuel supply period to the second pressure chamber 11 can be controlled, and the fuel injection timing can be controlled.

Next, a method of controlling the fuel injection amount will be explained.

As shown in FIG. 2, when the solenoid valve 15 is closed during the pressure-feeding stroke of the pressure-feeding plunger 5, after the injection timing control is performed by the timing plunger 9, the first
As the pressure inside the pressure chamber 10 increases, fuel injection from the injection nozzle is started.

Thereafter, as shown in FIG. 4, when the solenoid valve 15 is opened at 1° during pressure feeding, the high pressure fuel in the first pressure chamber 10 flows through the passages 13, 14, solenoid valves 15, and 16. As the fuel passes through and escapes, the pressure inside the first pressure chamber 10 decreases and the fuel injection ends.

If the opening timing of the electromagnetic valve 15 is advanced and opened at the tea timing, fuel injection ends earlier and the fuel injection amount decreases.

Conversely, if the opening timing of the electromagnetic valve 15 is delayed, the fuel injection period becomes longer and the fuel injection amount increases.

As mentioned above, in the pumping stroke of the pumping plunger 5,
By controlling the opening timing of the electromagnetic valve 15, the fuel injection amount can be controlled.

Note that the opening timing of the solenoid valve 15 is determined at the time 1.0 from the reference signal as shown in FIG. is calculated by a computer (not shown), and based on the calculation result, a valve opening signal is given to the electromagnetic valve 15, and the valve is opened.

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. Furthermore, although the fuel compression mechanism in the above-described embodiments is constructed using an inner cam system, those skilled in the art will easily understand that it can also be constructed using other compression systems, such as a face cam system or an Araku cam system.

〔Effect of the invention〕

As explained in detail above, according to the present invention, by using only one solenoid valve, the fuel injection timing can be controlled by the valve closing timing, and the fuel injection amount can be controlled by the valve opening timing, so the structure is simple and inexpensive. This has the excellent effect of providing a 8-fuel injection pump.

[Brief explanation of drawings]

1 to 4 relate to an embodiment of the present invention, and FIG. 1 is a cross-sectional view of the embodiment during the fuel intake stroke, and FIG.
The figure is a cross-sectional view of the fuel discharge stroke of the embodiment, FIG. 3 is a cross-sectional view taken along the line A-A in FIG. The operating characteristic diagrams representing the correspondence relationships are shown respectively. 9... Timing plunger, 10... First pressure chamber 211... Second pressure chamber, 13... Control passage, 1
4゜16... Fuel passage, 15... Solenoid valve, 17...
・Suction fuel passage, 18, 24. 25...Discharge passage, 4
5. -46°22...Suction passage, 40...Check valve, 100...Compression chamber.

Claims (1)

[Claims] A pressure chamber that communicates with a compression chamber (100) that receives compression as the pump rotates is divided into two by a timing plunger (9) that is slidably fitted into the pressure chamber and communicates with the compression chamber (100). In a fuel injection pump that includes a first pressure chamber (10) and a second pressure chamber (11) that does not communicate with the compression chamber (100), the first pressure chamber (10)
A control passage (13) that communicates with
, 25), which communicates the intake fuel passage (17) with the second pressure chamber (11), and
A check valve (40) that allows flow only to the low pressure side is provided in the passage communicating with the control passage (1) and the low pressure side.
3) and the intake fuel passage (17), each of which is provided with a fuel passage (14, 16) that selectively communicates with the intake fuel passage (17).
A fuel injection pump characterized in that one opening/closing means (15) is provided in the middle of parts 4 and 16).