JPS59119060A - Unit injector for diesel engine - Google Patents

Abstract

PURPOSE:To prevent a rapid pressure rise from occurring in a combustion chamber and reduce the quantity of a harmful exhaust gas, by injecting a fuel stepwise through a first-stage injection and a main injection. CONSTITUTION:In the unit injector 10, a pumping plunger 12 is slidingly reciprocated in accordance with the rotation of a cam shaft 38, in which case a quantity-regulating plunger 14 is moved in accordance with the pressure generated by forcing-in of the pumping plunger 12, and by the movement of the plunger 14, the fuel charged on the downstream side of a check valve 36 is compressed, and the first-stage injection and the main injection are effected stepwise. In the main injection stage, when the plunger 14 is moved to a predetermined position, a pumping chamber 32 is communicated to a main injection cut-off port 18, thereby finishing the main injection.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a unit injector used in a diesel engine, particularly a unit injector that injects fuel in a diesel engine in stages through initial injection and main injection to improve fuel combustion. Regarding injectors.

Generally, such unit injectors are mounted directly on the cylinder head of a diesel engine and are driven by the rotation of the diesel engine's camshaft.

The unit injector also prevents a sudden pressure rise in the combustion chamber and eliminates hydrocarbons (H) contained in the exhaust gas.
C) It is required to reduce nitrogen oxides (NOx) and improve fuel combustion, and in order to meet these requirements, it is necessary to perform fuel injection in stages as initial stage injection and main injection. desirable.

However, since the conventional unit injector has an extremely complicated structure, it is difficult to perform such stepwise injection of fuel.

The purpose of this invention is to perform fuel injection in stages as an initial stage injection and a main injection, to prevent a sudden pressure rise in the combustion chamber, and to reduce hydrocarbons and nitrogen oxides contained in exhaust gas. The object of the present invention is to provide a unit injector that improves combustion, simplifies the structure, and improves applicability to diesel engines.

For those tasks, the unit injector used in the diesel engine of this invention has a needle spindle bore with a valve seat and multiple orifices,
and a valve body having a blanker Dare communicating with the fuel reservoir of the needle spindle Dare, and arranged so as to be reciprocally slidable on the Granja Dare, and
A pumping plunger is pushed into its plunger bore against a valve spring by a cam attached to a camshaft driven by a diesel engine, and a needle spring pushes the valve into its plunger bore.
a nozzle needle mated to the needle spindle bore to be seated in the seat; and a pumping sylanger to cooperate with the pumping sylanger to form a pumping chamber within the plunger bore. - a metering grunger fitted in a floating and reciprocating manner within the bore; and a fuel pump port formed in the valve body to communicate with the fuel reservoir of the needle spindle bore.

a fuel tank port opened in the granger to be opened and closed by the pumping plunger;・A first stage injection cut-off port opened to the der, and a main injection cut-off port opened to the plunger der to be opened and closed by its metering sylanger.
port and its fuel tank port its pumping port.
A cut formed in the pumping plunger communicates the pumping chamber with the initial cut-off port after being closed by the granger.
It includes an off communication passage and a solenoid valve that regulates the amount of fuel flowing from the fuel pump to its fuel pump port.

Hereinafter, preferred specific examples of the unit injector used in the diesel engine of the present invention will be described with reference to the drawings.

The figure shows a unit injector 10 for use in a diesel engine of the invention, which is embodied as being used in a truck diesel engine.

The unit injector 10 has a valve seat 2
2 and a plurality of nozzles 23, 24, and a valve body having a silanger bore 26 communicating with a fuel reservoir 25 of the needle spindle bore 21 via a fuel passage 29. 11 and a cam 39 of a cam shaft 38 which is arranged to be reciprocally slidable in its planter bore 26 and is driven by a diesel engine mounted on the truck.
Pumping plunger 12 is pushed into its gland bore 26 against spring 35 and its valve seat 22 is pushed by needle spring 30.
A nozzle needle 13 fitted in its needle spindle bore 21 and a pumping gland 12 cooperate to form a pumping chamber 32 in its plunger bore 26 so as to be seated therein. Thus, the metering plunger 14 is fitted in the syringe bore 26 so as to be able to reciprocate in a floating state, and the fuel reservoir 25 of the needle spindle bore 21 is communicated via the fuel passage 29. , a fuel pump port 15 formed in the valve body 11, a fuel tank port 16 opened in the silanger bore 26 to be opened and closed by the pumping granger 12, and a nozzle 23, An initial injection cut-off port 17 is opened in the plunger bore 26 at a predetermined distance from the fuel tank port 16 in the direction away from the fuel tank port 24 and is opened and closed by the metering gland 14. , that plant
Main injection cut-off port 18 open to bore 26
and after the fuel tank port 16 is closed by the pumping planter 12, the pumping plant
The chamber 32 is connected to its initial injection cut-off port 17.
a cut-off communication passage 19 formed in the pumping granger 12 to communicate with the fuel pump port 15; and a solenoid valve 20 for regulating the amount of fuel flowing from the fuel pump (not shown) to the fuel pump port 15. It is composed of

The valve body 11 is attached to the cylinder head of a diesel engine mounted on a truck so that the lower end side is accommodated in the combustion guide, and a valve seat 22 and a plurality of nozzles 23, 2 are located on the lower inner side. A needle spindle bore 21 with a is formed, and
On the upper end side, there is a plunger that opens upward.
A bore 26 is formed.

The grand gloss bore 26 includes a pumping plunger bore 27 formed approximately in the center above the valve body 11, and a pumping plunger gear 2.
The metering plunger bore 28 is connected to the lower part of the pumping plunger bore 27 and is offset to one side with respect to the axis of the pumping plunger bore 27. A stopper stage 40 is formed at the boundary with the plunger bore 28.

The metering plunger bore 28 is connected via a fuel passage 29 to the fuel reservoir 2 of the needle spindle bore 21.
5 has been contacted.

Of course, the valve body 11 can be used with such a plunger.
It is constructed from a plurality of divided parts in consideration of workability when forming the diameter 26 and installation of the pumping syringer 12, metering syringer 14, etc., which will be described later.

The pumping plunger 12 is arranged so as to be able to reciprocate and slide in the pumping gland bore 27 of the pulp body 11, and has a follower portion that projects above the pumping plunger bore 27 integrally at its upper end. In addition, a valve spring 35 is disposed between the upper end surface of the pulp body 11 and a portion of the follower.

Of course, the upper surface of the follower portion contacts the cam 39 of the cam shaft 38 of the diesel engine, and the cam
Rotation of the shaft 38 forces the pumping granger 12 into the pumping plunger bore 27 against the valve spring 35 .

The nozzle needle 13 is reciprocally slidable on the needle spindle gear 21 so as to be seated on its valve seats 22 by a needle spring 30 disposed above the needle spindle gear 21. Fitted together.

A spring seat 31 is located between the upper end of the nozzle needle 13 and the lower end of the needle spring 30.
Of course, if it is arranged.

The metering grunge 14 is arranged in a metering plunger bore 28 of the pulp body 11 so as to be able to slide back and forth in a floating state.

Of course, during the reciprocating sliding of the metering plant gear 14, the upward sliding position is regulated by the stopper formed on the pulp body 11. This is done by one stage 40.

Due to the arrangement of the metering plunger 14, a pumping chamber 32 is formed in the granger pore 26 of the pulp body 11 in cooperation with the lower end face of the pumping plunger 12. be done.

Fuel pump port 15 is needle spindle?
It is formed approximately in the center of the pulp body 11 so as to communicate with the fuel reservoir 25 of the pulp body 11 .

That is, the fuel pump port 15 is extended inwardly such that one end is in communication with the metering chamber bore 28, and the fuel pump port 15 is in communication with the metering chamber bore 28 and the fuel passage 29 through the metering chamber bore 28 and the fuel passage 29. Tame! 1125 has been contacted.

The fuel pump port 15 is connected via a fuel line 37 to the discharge side of a fuel pump (not shown).

Of course, there is a check valve 3 inside the fuel pump port 1.
6 is arranged, and the fuel on the fuel reservoir 25 side is the fuel I.
The structure is designed to prevent backflow to the operating side.

The fuel tank port 16 opens into an upper portion of its plunger bore 26, ie, a pumping granger 27, to be opened and closed by its pumping granger 12.

The fuel tank port 56 is slightly opened when the follower portion of the pumping plunger 12 is in contact with the base inner portion of the cam 39, and the follower portion is in contact with the protruding portion of the cam 39. The pulp body 11 is formed in such a way that it is occluded when the pumping granger 12 is pushed in slightly while in contact.

The fuel tank port 16 is connected to a fuel line (not shown).
Connected to the fuel tank via.

The first stage injection cut-off port 17 has its nozzle 23,
24, i.e. in the upper part of the pulp body 11, at a predetermined distance above the fuel tank port 16.
It opens into a plunger bore 27. The first stage injection cut-off port 17 is connected to a fuel tank via a fuel pipe (not shown).

The main injection cut-off port 18 is connected to the lower portion of its plunger bore 26, i.e., to the metering granger bore 2, to be opened and closed by its metering silunger 14.
It is opened at 8. The main injection cut-off port 18 is connected to the fuel tank via fuel piping (not shown). Of course, the main injection cut-off port 18 is opened when the metering syringer 14 is slid downward a predetermined distance.

The cut-off communication passage 19 is connected to the fuel tank port 1.
6 is configured in the pumping silane 12 to communicate the pumping chamber 32 with the initial injection cutoff 17 after the pump 6 is closed by the pumping silane 12.

That is, after the pumping gland 12 is pushed against the pulp spring 35 and the fuel tank port 16 is closed by the pumping silanger 12, the cut-off communication passage 19 is connected to the first stage injection cut-off passage 19. to be contacted off-port 17,
Consisting of a ring groove 33 formed on the outer periphery of the pumping granger 12 and a communication hole 34 formed inside the pumping granger 12 so as to communicate the pumping chamber 32 with the ring groove 33. has been done.

The solenoid valve 20 is provided in a fuel pipe 37 that connects the discharge side of the fuel pump to the fuel pump port 15 of the pulp body 11, and is connected to the fuel pump port 15 from the fuel pump.
It regulates the amount of fuel supplied to the

The amount of fuel flowing into the fuel pump port 15 is:
It is determined by the opening time of the solenoid valve 20, and the opening/closing control of the solenoid valve 20 is performed according to an electrical output signal from the speed governor (not shown) of the diesel engine.

Next, the operation of the unit injector 10 configured as described above will be explained.

The fuel supplied from the fuel pump is regulated to a predetermined supply amount by opening and closing the solenoid valve 2°, and the fuel is supplied to the fuel pump port 1.
5, and the downstream side of the check valve 36 is filled with a predetermined amount of fuel.

In such a state, when the cam shaft 38 is rotated, the pimping syringe 12 is slid back and forth in accordance with the rotation, but during this back and forth sliding, the pumping sylanger 12 is moved against the pulp spring 35. When the pumping silane 12 is pushed in slightly against the
closes the fuel tank port 16 and applies a pressure in the pumping chamber 32 corresponding to the slight push of the pumping granger 12, moving the metering granger 14 toward the nozzle 28,24.

Therefore, in the valve body 11, the fuel filled downstream of the check valve 36 is compressed and supplied to the fuel reservoir 25, the nozzle needle 13 is lifted against the needle spring 30, and the nozzle 23.24 Fuel is injected from the first stage to perform the first stage injection.

Then, when the pumping granger 12 is pushed in slightly, the pumping chang/? 32 is connected to the first-stage injection cut-off port 17 via the cut-off communication passage 19, and the fuel in the pumping chamber 32 is returned to the fuel tank side.

That is, no pressure acts on the metering gland 14, and the fuel filled downstream of the check valve 36 is not compressed.
First stage injection ends.

Furthermore, when the pumping granger 12 is pushed in, the fuel tank port 16 and the first stage injection cut-off port 17 are each closed by the pumping jig silanger 12, and the pumping granger 12 is closed again.
Pressure corresponding to the pushing of the plunger 12 is applied within the pumping chamber 32, the metering plunger 14 moves to the nozzle 2g, 24 side, and main injection is performed in substantially the same manner as in the case of the first-stage injection described above. .

From such a condition, the pumping plunger 12
is pushed further and the metering granger 14 moves further toward the nozzle ports 2g and 24, the main injection cutoff d? -) 1B is opened and its pumping chamber 32 is communicated with its main injection cut-off port 18, and the fuel in its pumping chamber 32 is returned to the fuel tank side.

Therefore, no pressure is applied to the metering granulator 14, and the fuel filling the downstream side of the check valve 36 is not compressed, and the main injection ends.

In the above-mentioned unit/injector 10, the metering lunge 14 moves in accordance with the pressure generated by pushing the pumping syringe 12, and the metering plunger 14 moves.
, the fuel filling the downstream side of the check valve 36 is compressed, and the first-stage and main injections are performed in stages.
moves into position, the pimping chamber 3
2 to the main injection cut-off port 18 to terminate the main injection, but when the metering granger 14 moves into position, the downstream side of the check valve 36 is connected to the upstream side. It is also possible to terminate the main injection.

In such a case, a ring groove is formed on the outer periphery of the metering silunger 14, and a communication hole is formed inside the metering lunge 14 to connect the downstream side of the check valve 36 to the ring groove. The valve body 11 also has a main injection cut-off port 18, which is connected to the ring groove when the metering granger 14 moves into position, in place of the main injection cut-off port 18 described above. - Form an off port and connect its main injection cut-off port to the upstream side of its check valve.

According to this invention configured as above, fuel injection is performed in stages as initial stage injection and main injection, a sudden pressure rise in the combustion chamber is prevented, and hydrocarbons and nitrogen oxides contained in the exhaust gas are reduced. The fuel combustion rate is reduced, fuel combustion is improved, and the structure is simple and compact, making it possible to apply it not only to large diesel engines but also to small diesel engines, making it practical.

[Brief explanation of drawings]

The figure is a longitudinal cross-sectional view schematically showing a unit injector used in a diesel engine of the present invention, which is embodied as being used in a diesel engine for a truck. DESCRIPTION OF SYMBOLS 10... Unit injector used in a diesel engine, 11... Valve body, 12... Pumping plunger, 13... Nozzle needle, 14...
... Metering plunger, 15... Fuel pump port,
16... Fuel tank port, 17... First stage injection cut-off port, 18... Main injection cut-off port.
Port, 19...Cut-off communication path, 20...i
ff magnetic valve, 21...needle spindle bore,
'22... Valve seat, 23.24... Nozzle,
25...Fuel reservoir, 26...Grand gloss bore, 3
0... Needle Suff0 ring, 32... Pumping chamber, 35... Valve spring, 38...
...Cam shaft, 39...Cam.

Claims (1)

[Claims] A needle spindle der with a valve seat and a plurality of nozzles;
The valve body has a plunger and a valve connected to the fuel reservoir of the cylinder, and the valve body is arranged so as to be able to reciprocate and slide on the plunger and cylinder. The pumping valve is pushed into its granger against the valve spring by the
a sylanger and a nozzle needle fitted into its needle spindle der so as to be seated on its valve seat by a needle spring;・To form a chamber,
A metering plunger is fitted into the valve body so that the plunger can be slid back and forth in a floating state; a pump port; a fuel tank port open to the plunger to be opened and closed by the pumping plunger;
an initial injection cut-off port opened in the plunger bore at a predetermined distance from the port, and a main injection cut-off opened in the syringer bore to be opened and closed by the metering syringe. port and, after the fuel tank port is closed by the pumping plunger, the pumping chamber/s
a cut-off communication passage formed in the pumping gland so as to communicate the first-stage injection cut-off port with the first-stage injection cut-off port, and a solenoid valve that adjusts the amount of fuel supplied from the fuel pump to the fuel pump port. Unit injectors used in diesel engines including.