JPH0367060A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To securely discharge the fuel immediately after air bleeding and enhance the starting characteristic of engine by opening a delivery valve prior to an overflow valve with the pressure of supplied fuel when it is supplied to the plunger chamber at the time of air bleeding. CONSTITUTION:The opening pressure of a delivery valve 15 is set lower than the opening pressure of an overflow valve 23. Therefore, the delivery valve 15 is opened with pressure rise in a fuel injection pump 1. Accordingly the air in a fuel chamber 11 and plunger chamber 12 as well as the air in the delivery valve 15 on its plunger chamber 12 side is all passed through the delivery valve 15 and exhausted from the discharge hole 13, and the fuel injection pump 1 is filled with the fuel. Thus, the discharge passage 14 of the delivery valve 15 on its plunger chamber 12 side and the plunger chamber 12 can be filled with the fuel, which permits certain discharging of the fuel immediately after air bleeding. This should enhance the starting characteristics of internal combustion engine after air bleeding.

Description

[Detailed description of the invention] [Usage field of industry 1] The present invention relates to air bleeding from a fuel injection pump.

[Prior Art] When a fuel injection pump is assembled into an internal combustion engine, an air bleed operation is performed to remove the air inside the fuel injection pump.

Air bleeding is generally performed by operating a priming pump attached to the feed pump.

When operated, the priming pump directs fuel through a supply passage into the fuel plunger chamber of the pump element.

On the other hand, the opening pressure of the overflow valve provided in the supply passage is set lower than the opening pressure of the delivery valve provided in the discharge passage.

Therefore, when the priming pump pumps the fuel F1 into the fuel injection pump, the fuel compresses the air inside,
The compressed air is discharged through an overflow valve with a low opening pressure.

[Problem to be Solved by the Invention +M] Generally, the fuel discharge port of a fuel injection pump is provided at the upper end of the fuel injection pump. Therefore, air does not escape from the inside of the discharge passage on the plunger chamber side of the delivery valve even if air is vented.

For this reason, air is pumped out from the discharge port of the fuel injection pump for several strokes immediately after starting the fuel injection pump.

In other words, conventional fuel injection pumps have had the problem of poor startability of the internal combustion engine after air is removed from the fuel injection pump.

An object of the present invention is to provide a fuel injection pump that also discharges air from the plunger chamber side of a delivery valve when air is vented, and reliably discharges fuel immediately after the air is vented.

[Means for Solving the Problems] In order to achieve the above object, the fuel injection pump of the present invention employs the following technical means.

A fuel injection pump includes a pump element that pumps fuel guided into a plunger chamber by reciprocating motion of a plunger, and an overflow valve that opens when the pressure in a supply passage communicating with the plunger chamber reaches a set pressure. and a delivery valve provided in a discharge passage communicating with the plunger chamber.

When the delivery valve supplies fuel into the plunger chamber through the supply passage during air bleeding,
The valve is provided to open before the overflow pulp due to the pressure of the supplied fuel.

[Operation] In order to bleed air, the priming pump or the like is operated to forcefully feed fuel from the supply passage into the first langeer chamber. Then, the air in the supply passage, the plunger chamber, and the plunger chamber side of the delivery valve is compressed by the supplied fuel.

Here, at least when venting air, the delivery valve opens before the overflow valve.

Therefore, the air compressed by the supply of fuel is discharged from the delivery valve. Then, after the air exits at tJF, the fuel flows out from the delivery valve, completing the air bleeding.

[Effects of the Invention] As explained above, in the present invention, fuel flows out from the delivery valve by removing air. This means that the plunger chamber and the sand outlet passage on the granger chamber side of the delivery valve are filled with fuel.

Therefore, the fuel injection pump reliably discharges fuel immediately after air is removed, and the startability of the internal combustion engine after air is removed is improved.

[Example] Next, a fuel injection pump of the present invention will be described based on an example shown in the drawings.

(Configuration of the first embodiment) FIG. 1 shows a sectional view of a type fuel injection pump.

The size fuel injection pump 1 has a pump element 2 for each cylinder.
It is a pump equipped with Each pump element 2 compresses fuel sent from a feed pump (not shown) and injects it to an injection nozzle (not shown) attached to each fuel chamber of an internal combustion engine (not shown).

The fuel injection pump 1 is roughly divided into ζ pump element 2,
It consists of a driving means 3, an injection amount adjusting means 4, and a pump housing 5 that houses these.

The pump element 2 includes a plunger 6 that is reciprocated by a driving means 3, and a cylindrical cylinder 7 that houses the plunger 6.

The 1-land gear 6 is formed with a control group 8 that is inclined upward. This control group 8 is
It communicates with the upper end of the plunger 6 through a hole (not shown) formed inside.

The cylinder 7 is provided with a feed hole 10 on the upper side. This feed hole 10 forms part of the supply passage of the present invention, and includes a fuel chamber 11 (which together with the feed hole 10 constitutes a supply passage) that supplies fuel from the feed pump to the surroundings of the cylinder 7 , and a fuel chamber 11 that supplies fuel from the feed pump to the surroundings of the cylinder 7 It communicates with the plunger chamber 12 inside. The feed hole 10 serves as a supply port for guiding the fuel in the fuel chamber 11 into the cylinder 7, and also as a discharge port for discharging the fuel in the plunger chamber 12 into the fuel chamber 11 at the end of pressure feeding.

A discharge passage 14 is provided above the cylinder 7 to guide the fuel pumped by the plunger 6 to the discharge port 13. A delivery valve 15 is arranged in this discharge passage 14 . The delivery valve 15 is a check valve that has the function of preventing the fuel guided to the discharge port 13 from flowing back into the plunger chamber 12 and the suction function of preventing the fuel from leaking after the injection nozzle. It is biased toward the plunger 6 side.

Note that the opening pressure of the delivery valve 15 is set by a delivery valve spring 16.

The drive means 3 includes a camshaft 17, a tappet 18, and a granger spring 19. The camshaft 17 is
Rotationally driven by an internal combustion engine. The tappet 18 follows the movement of the cam of the camshaft 17, and the plunger 6
Press] -0 It's a geromono. Plungas Gering 1
9 pushes down the plunger 6 and the tab 1-18. Therefore, when the camshaft 17 rotates, the plunger 6 reciprocates along the trajectory of the cam.

The injection amount adjusting means 4 rotates the plunger 6 and adjusts the effective stroke until the control group 8 and the feed hole 10 coincide when the plunger 6 moves upward. The injection amount adjusting means 4 includes a control rack 20, a control sleeve 21. It consists of a coupling 22. The control rack 20 is connected to a governor (not shown) and rotates the control sleeve 21 in accordance with the rotational speed of the internal combustion engine. The coupling 22 rotates the plunger 6 without interfering with the reciprocating movement of the plunger 6.

The pump housing 5 is a metal container that houses and holds the above-mentioned parts and protects the inside.

The pump housing 5 includes the above-described fuel chamber 11 therein. This fuel chamber 11 is provided with an overflow valve 23. The overflow valve 23 drains the fuel in the fuel chamber 11 to the outside for the purpose of protecting the inside when the pressure inside the fuel chamber 11 increases, such as when fuel injection is stopped and the internal combustion engine is rotating. It is a check valve for release.

The overflow valve 23 is connected to the fuel chamber 11
The valve case 25 is screwed into a hole 24 communicating with the valve case 25. The valve case 25 is provided with a discharge passage 26 that guides the fuel in the fuel chamber 11 to the outside of the pump housing 5. The discharge passage 26 includes a stepped portion 27 that temporarily becomes larger in diameter on the way to the outside. The stepped portion 27 is a valve seat of the overflow valve 23 , and a spherical valve body 28 is pressed against it by an overflow spring 29 . The valve body 28 and the overflow spring 29 are housed in the discharge passage 26 through an insertion hole 30 at the end of the valve case 25, and the insertion hole 30 is inserted into the discharge passage 26 by a bolt 31.
is retained within the discharge passageway 26 by blocking it. The opening pressure of the overflow valve 23 is set by an overflow spring 29. The opening pressure of the overflow valve 23 in this embodiment is set higher than the opening pressure of the delivery valve 15.

(Operation of the embodiment) Next, the operation of the embodiment according to the present invention will be briefly explained.

When the fuel injection pump 1 is assembled and mounted on a vehicle, the fuel chamber 11. Air enters the plunger chamber 12. Therefore, a fuel pipe (not shown) is fitted into the feed pump of the fuel injection pump 1, and a manual priming pump attached to the feed pump is operated. Then, the fuel flows into the fuel chamber 11 through the unretracted hollow screw, passes through the feed hole 10, and reaches the 1-lunger chamber 12. As the priming pump continues to operate, the portion that becomes the fuel passage increases. In this embodiment, the opening pressure of the delivery valve 15 is
The pressure is set lower than the opening pressure of the overflow valve 23. Therefore, the delivery valve 15 opens due to the increase in pressure within the fuel injection pump 1.

As a result, the fuel chamber 11, plunger chamber 12
the air inside, and the plunger chamber 1 of the delivery valve 15
All of the air on the second side passes through the delivery valve 15 and is discharged from the discharge port 13, and the fuel injection pump 1 is filled with fuel.

(Effects of Example) According to this example, the plunger chamber 12 and the discharge passage 14 on the plunger chamber 12 side of the delivery valve 15 can be filled with fuel, so that the fuel can be reliably discharged immediately after air is removed. As a result, the startability of the internal combustion engine after air removal is improved compared to the conventional method.

(Second example) A second embodiment is shown in FIGS. 2 to 4.

This embodiment is an embodiment in which the opening pressure of the overflow valve 23 is lower than that of the delivery valve (see the first embodiment).6 The overflow valve 23 of this embodiment has a valve case 25 and an insertion hole 30. bolt 31 screwed into
A washer 32 is placed between the two. The washer 32 of this embodiment, as shown in FIGS. 3 and 4,
It is divided into two parts so that the bolt 31 can be attached and detached without removing it from the insertion hole 30.

Note that the washer 32 is removed during air bleeding and is attached after air bleeding is completed.

The thickness of the washer 32 is such that when the washer 32 is not attached to the overflow valve 23, the overflow spring 29 is strongly compressed by the bolt 31, and the opening force of the overflow valve 23 is higher than that of the delivery valve. When attached, the compressive force of the overflow valve 29 is weakened, and the opening pressure of the overflow valve 23 is set to be lower than that of the delivery valve.

That is, in this embodiment, by performing air bleeding without the washer 32, internal air is discharged from the delivery valve as in the first embodiment.

After the air is removed, the washer 32 is attached so that the opening pressure of the overflow valve 23 becomes lower than that of the delivery valve.

(Third example) FIG. 5 shows a third embodiment.

In this embodiment, like the second embodiment, the overflow valve 2
This is an example in which the valve opening pressure of No. 3 is lower than that of the delivery valve (see the first example).

The overflow valve 23 of this embodiment has a rod-shaped bottle 33 provided at the end of a bolt 31 that is screwed into an insertion hole 30. This bottle 33 presses the valve body 28 against the stepped portion 27 by removing the washer 32 and tightening the bolt 31 to the valve case 25 .

Therefore, when removing air, by removing the washer 32 and tightening the bolt 31, the overflow valve 2
3 no longer opens, and as a result, internal air is discharged from the delivery valve.

After the air is removed, the washer 32 is attached, so that the valve body 28 is released from the pressure applied by the bottle 33, and the opening pressure of the overflow valve 23 becomes lower than that of the delivery valve.

(Fourth example) FIG. 6 shows a fourth embodiment.

This embodiment, like the second and third embodiments, is an embodiment in which the opening pressure of the overflow valve 23 is lower than that of the delivery valve (see the first embodiment).

The overflow valve 23 of this embodiment is provided with an umbrella-shaped piston 34 that changes the alignment of the overflow spring 29 on a bolt 31. It is inserted into the hole 35.

On the other hand, an adapter 36 is attached to the overflow valve 23 when air is removed. This adapter 36 is attached to the bolt 3
A push rod 37 is provided to be inserted into the hole 35 of No. 1.

When the adapter 36 is attached to the overflow valve 23, this push rod 37 pushes the piston 34, compresses the overflow spring 29, and makes the opening pressure of the overflow valve 23 higher than the opening pressure of the delivery valve. be.

After removing air, connect the adapter 36 to the overflow valve 2.
3, the compression force of the overflow spring 29 by the piston 34 is weakened, and the opening pressure of the overflow valve 23 becomes lower than the opening pressure of the delivery valve.

(Fifth example) FIG. 7 shows a fifth embodiment.

This embodiment, like the second to fourth embodiments, is an embodiment in which the opening pressure of the overflow valve 23 is lower than that of the delivery valve (see the first embodiment).

The overflow valve 23 of this embodiment has the bottle 33 shown in the third embodiment provided at the end of the piston 34 of the fourth embodiment.

That is, when air is vented, the adapter 36 is attached to the overflow valve 23, the valve body 28 is urged against the stepped portion 27 by the bottle 33, and opening of the overflow valve 23 is restricted. After removing the air, remove the adder 36 from the overflow valve 23 to remove the bottle 3.
The regulation of the valve body 28 by 3 is removed, and the opening pressure of the overflow valve 23 becomes lower than that of the delivery valve.

(6th example) FIG. 8 shows a sixth embodiment.

FIG. 8 shows a cross-sectional view of the supply type fuel injection pump 38.

The supply type fuel injection pump 38 adjusts the amount of discharged fuel by opening and closing a solenoid valve 39, and the discharged fuel is sent to a fuel accumulating chamber (not shown). Any one of the above-mentioned 1st to 5th embodiments can be applied to the overflow valve 23 of this example.

As a result, the supply type fuel injection pump 38 reliably discharges fuel immediately after air is removed.

(Seventh Example) FIG. 9 shows a seventh embodiment.

The solenoid valve 39 provided at the top of the supply-type fuel injection bong 1 (see the sixth embodiment) is connected to a supply passage that sends fuel from the fuel chamber (see the sixth embodiment) to the plunger chamber (see the sixth embodiment). A valve 41 that opens and closes is provided.The valve 41 is provided with an armature 42.The armature 4
2 is biased by a spring 43 so that the valve 41 opens.

The armature 42 and spring 43 are housed in a chamber 44 that communicates with the supply passage.

In this embodiment, this chamber 44 is communicated with the outside of the electromagnetic valve 39 via a drain boat 45, and this drain boat 45 is closed with a bolt 46.

This bolt 46 is removed when air is removed. Then, the priming pump is operated, and the bolt 46 is tightened when the internal air has been completely discharged by the drain bow 1/45.

In this state, the air in the discharge passage (see the sixth embodiment) on the granger 6 side of the delivery valve (see the sixth embodiment) is not released. For this reason, after blocking the drain boat 45 with the bolt 4G, the priming pump is activated,
Any one of the first to fifth embodiments described above is applied to an overflow valve (not shown), and internal air is discharged from the delivery valve.

In this embodiment, compared to the sixth embodiment, the degree of internal air removal due to air venting is even greater.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a size-type fuel injection pump showing a first embodiment of the present invention. 2 to 4 show a second embodiment of the present invention, in which FIG. 2 is a sectional view of the overflow valve, FIG. 3 is a side view of the washer, and FIG. 4 is a front view of the washer. FIG. 5 is a sectional view of an overflow valve showing a third embodiment of the present invention. FIG. 6 is a sectional view of an overflow valve showing a fourth embodiment of the present invention. FIG. 7 is a sectional view of an overflow valve showing a fifth embodiment of the present invention. FIG. 8 is a sectional view of a supply type fuel injection pump showing a sixth embodiment of the present invention. FIG. 9 is a sectional view of a solenoid valve showing a seventh embodiment of the present invention. In the diagram: 1...Fuel injection pump 2...Pump element l-6...Plunger 10...Feet hole (supply passage) 11...Fuel chamber (supply passage) 12...Plunger chamber 14...・Discharge passage 15
... Delivery valve 23 ... Overflow valve Fig. 2 Agent Kenji Ishiguro vM3 Fig. 14ryJ Fig. 1 ... Fuel injection pump 2 ... Pump element 6 ... Plunger 10 ... Feed hole (supply passage ) 11... Fuel chamber (supply passage) 12... 1 lunge chamber 14... Discharge passage 15 Delivery valve 23... Overflow valve 0

Claims (1)

[Claims] 1) A pump element that pumps fuel guided into the plunger chamber by the reciprocating motion of the plunger, and an overflow valve that opens when the pressure in the supply passage communicating with the plunger chamber reaches a set pressure. A fuel injection pump comprising a valve and a delivery valve provided in a discharge passage communicating with the plunger chamber, the delivery valve supplying fuel into the plunger chamber via the supply passage when air is removed. A fuel injection pump, characterized in that the fuel injection pump is configured to open before the overflow valve due to the pressure of the supplied fuel.