JPS59119061A - 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 pas, by injecting a fuel stepwise through a first-stage injection and a main injection. CONSTITUTION:The unit injector 10 is comprised of a bent-type valve main body 11 provided with a plunger core 26 communicated to a needle spindle bore 21 and a fuel reservoir 25 through a fuel passage 29, a pumping plunger 12 operated by a cam 39 and a lifter 40, a quantity-regulating plunger 14 fitted in the plunger bore 26 so that it can be slidingly reciprocated in a floating condition, a first-stage injection cut-off port 17 opened into the plunger bore 26 with a predetermined spacing from a fuel tank port 16, and a main injection cut-off port 18 opened into the plunger bore 26 so as to be opened and closed by the plunger 14.

Description

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

Generally, this type of unit injector is mounted directly on the cylinder head of a diesel engine and is driven by the rotation of the cam shaft of the diesel engine.

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, because conventional unit injectors have extremely complex structures, it is difficult to perform such stepwise injection of fuel, and installation into the cylinder head is difficult. Since the cam follower of the unit injector is installed so as to be in contact with the cam side of the camshaft, the installation position of the unit injector is determined by the position of the camshaft, making it difficult to be versatile. In particular, it has been difficult to apply this method to small diesel engines for vehicles.

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 fixed wood oxides contained in the exhaust gas. To provide a unit injector for use in a diesel engine, which improves the combustion of fuel, has a simple structure, can be applied not only to large diesel engines but also to small diesel engines, and can further downsize the entire engine. It is in.

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 bent valve body having a plunger bore communicating with the fuel reservoir of the needle spindle bore, and a bent valve body disposed so as to be reciprocally slidable in the plunger bore,
A pumping plunger is pushed into its plunger bore against a valve spring by a cam attached to a cam shaft driven by a diesel engine, and a needle spring pushes the pump into its valve seat. a nozzle needle fitted into the neat 9le spindle bore so as to be seated;
cooperating with the pumping plunger to form a pumping chamber within the plunger bore;
a metering cylinder fitted in the plantar bore so as to be able to reciprocate in a floating state; a fuel pump port formed in the valve body so as to communicate with the fuel reservoir of the needle spindle bore; a fuel tank port opened in the sylanger bore to be opened and closed by the pumping plunger;
In the direction away from the nozzle, the fuel tank
an initial injection cut-off port opened in its plunger bore at a predetermined distance from the port; and a main injection cut-off opened in its plunger bore to be opened and closed by the metering plunger.・Port and
a cut-off communication passage formed in the pumping syringe to communicate the pumping chamber with the initial cut-off port after the fuel tank port is closed by the pumping syringe; and a solenoid valve for regulating the amount of fuel flowing from the fuel pump port to the 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 lO used in a diesel engine of the invention, which is embodied as being used in a truck diesel engine.

The unit injector lO has valve seat 2
2 and a needle spindle with a plurality of orifices 23, 24? A 21 and its needle, spindle, and bore 21 fuel reservoir! A bent nozzle main body 11 having a plunger/gear 26 communicated with U25 via a fuel passage 29, and a diesel engine mounted on a truck and disposed so as to be able to reciprocate in the plunger/bore 26. a cam 39 of a cam shaft 38 driven by;
The pumping sealant 12 is forced into its plunger pore 26 against the valve spring 35 by the lifter 40 and its needle spindle is seated in its valve seat 22 by the needle spring 30. The nozzle needle 13 fitted to the dea 21 and its pumping plunger 1
2 to form a pumping chamber 32 within the granger bore 26.
The metering gland 14 is fitted in the 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 connected to the metering gland 14 through the fuel passage 29. A fuel pump port 15 formed in the main body 11 and a sylanger thereof to be opened and closed by the pumping plunger 12 thereof.
a fuel tank 16 opened in the bore 26;
An initial injection cut-off port 17 opened in the granger port 16 at a predetermined distance from the fuel tank port 16 in the direction away from the injection port 23, 24, and the metering plunger 14. a main injection cut-off port 18 opened in its syringe bore 26 to be opened and closed by its fuel tank;
Port 16 connects to its Hasomping plunger 12.
After the pumping plunger 12 is closed, a cut-off communication passage 19 formed in the pumping plunger 12 and a fuel inlet are connected to the pumping plunger 12 to connect the pumping plunger 32 to the first-stage injection cut-off port 17. The fuel pump port 15 includes a solenoid valve 20 that adjusts the amount of fuel flowing from the fuel pump port 15 (not shown) to the fuel pump port 15.

In a diesel engine mounted on a truck, the valve body 11 has a vertical portion that is attached to the cylinder head so that the lower end side is housed in the combustion chamber, and a vertical portion that extends at right angles from the upper end of the vertical portion. The valve seat 22 and the plurality of nozzles 2 are arranged on the lower inner side of the vertical part.
3.24 is formed with a needle spindle 21 and on the inside towards the upper end of its longitudinal part;
Inside the horizontal part, there is a roadside curving-shaped silanja.
A bore 26 is formed.

That plunger? A 26 is a pumping silanja that is extended with one end open inside its lateral portion.
A 27 and its pumping
The metering plunger 28 is connected to the other end of the granja bore 27, and its metering plunger ? A2
A stopper 42 is projected inward above 8.

That metering plunger? A 28 is connected to the fuel reservoir z of the needle spindle dere 21 via the fuel passage 29.
5 has been contacted.

Of course, the valve body 11 is not suitable for such a plunger.
It is constructed from a plurality of divided parts in consideration of workability when forming the a 26 and installation of the pumping syringer 12, metering plunger 14, etc., which will be described later.

The pumping granger 12 is arranged so as to be able to reciprocate and slide in the pumping granger pore 27 of the valve body 11, and has a follower part protruding from one end of the pumping plunger bore 27 integrated therein. In addition, a valve spring 35 is disposed between the end face of the lateral portion of the valve body 11 and the follower portion thereof.

Of course, the upper surface of the follower portion contacts one end of the lifter 40 driven by the cam 39 of the camshaft 38 of the diesel engine, and as the camshaft 38 rotates, the pumping f' ginger 12 It is pushed into its pumping plunger bore 27 against its valve spring 35.

The nozzle needle 13fd is reciprocatably fitted into the needle spindle bore 21 so as to be seated on its valve seat 22 by a needle spring 30 disposed above the needle spring bore 21. ing.

Between the upper end of the nozzle needle 13 and the lower end of the needle spring 30, there is a suf ring seat 3.
Of course, 1 is placed at the core.

The metering plunger 14 is arranged in a metering plunger bore 28 of the valve 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 plunger 14, the upward sliding position is restricted by the stopper 42 formed on the valve body 11.

Due to the metering plunger 14 being so arranged, a pumping chamber 32 is formed in the syringer bore 26 of the valve body 11 in cooperation with the lower end face of the pumping syringe 12. be done.

Fuel pump port 15 is needle spin.

It is formed extending in the axial direction in the vertical portion of the valve body 11 so as to communicate with the fuel reservoir 25 of the dollar bore 21 via a fuel passage 29.

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

Of course, a check valve 36 is disposed inside the fuel pump port 15 to prevent fuel from the fuel reservoir 25 from flowing back to the fuel pump.

The fuel tank port 16 has its valve body 11 opened and closed by its pumping plunger 12.
The pumping plunger bore 27 is opened at a position closer to the inside of the pumping plunger bore 27.

The fuel tank i-port 16 is slightly opened when the other end of the lifter 40 contacts the base inner portion of the cam 39 and the pumping granger 12 is not pushed into the pumping plunger bore 27; Further, the other end of the lifter 4o comes into contact with the protruding portion of the cam 39, and the pumping plunger 12
The valve body is configured to be occluded by the pumping plunger 12 when pushed into the bore 27. The fuel tank port 16 is connected to a fuel tank via fuel piping (not shown).

The first stage injection cut-off port 17 has its nozzle 23,
In the direction away from 24, ie in the lateral part of the valve body 11, it opens into the pumping granger bore 27 at a predetermined distance outwardly from the fuel tank port 16. The first stage injection cut-off port 17 is connected to a fuel pipe (not shown).
Connected to the fuel tank via.

A main injection cut-off port 18 opens into a metering syringer bore 28 in its granger bore 26 to be opened and closed by its metering plunger 14 . The main injection cut-off, IP-18, is
It 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 planter 14 is slid downward a predetermined distance.

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

That is, the cut-off communication passage 19 is connected to the first stage injection cut-off passage after the pumping granger 12 is pushed against the pulp spring 35 and the fuel tank port 16 is closed by the pumping granger 12. a ring groove 33 formed in the outer periphery of the pumping lunge 12 so as to communicate with the off-hole 17; It is configured with a communication hole 34 formed inside.

The solenoid valve 20 connects the discharge side of the fuel pump 0 to the valve body 11.
from the fuel pump to the fuel pump port 1.
The amount of fuel supplied to the fuel pump 5 is adjusted.

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 IO configured as described above will be explained.

The fuel supplied from the fuel pump is adjusted to a predetermined supply amount by opening and closing the solenoid valve 20, and 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 pumping plunger 12 is reciprocated by the lifter 40 in accordance with the rotation, but in this reciprocating movement, the pumping plunger 12 is When pushed slightly against the spring 35, the pumping plunger 12 closes the fuel tank port 16, and a pressure corresponding to the slight push of the pumping plunger 12 is applied within the pumping chamber 32. , the metering plunger 14 moves to the nozzle ports 23 and 24 side.

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. Fuel is injected from 24 and the first stage injection is performed.

Next, when the pumping plunger 12 is pushed in slightly, the pumping chamber 32 is communicated with the first stage injection cut-off port 17 via the cut-off communication passage 19, and the fuel in the pumping chamber 32 is discharged. It is returned to the fuel tank side.

That is, no pressure is applied to the metering fluorometer 14, the fuel filling the downstream side of the check valve 36 is not compressed, and the first-stage injection ends.

Furthermore, when the pumping plunger 12 is pushed in, the fuel tank port 16 and the first stage injection cut-off port 17 are each closed by the pumping plunger 12, and the pumping plunger 12 closes the fuel tank port 16 and the first stage injection cut-off port 17, respectively.
Pressure corresponding to the depression of the plunger 12 is applied within the pumping chamber 32, the metering plunger 14 moves toward the injection port 23, 24, 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 plunger 14 moves further toward the nozzle ports 23 and 24, the main injection cut-off port 18 is opened and the pumping chamber 32 is opened to the main injection cut-off port. - The fuel in the pumping chamber 32 is communicated with the port 18 and returned to the fuel tank side.

Therefore, no pressure acts on the metering plunger 14, the fuel filling the downstream side of the check valve 36 is not compressed, and the main injection ends.

In the unit injector 10 described above, the metering plunger 14 moves in accordance with the pressure generated by pushing the pumping plunger 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, and in the main injection stage, 1. The measuring plantsuya 1
4 moves into position, it communicates the pumping chamber 32 to the main injection cut-off port 18 to terminate the main injection, but when its metering plunger 14 moves into position, its It is also possible to connect the downstream side of the check valve 36 to the upstream side to terminate the main injection.

In such a case, a ring groove is formed on the outer periphery of the metering syringe 14, and a communication hole is formed inside the metering syringe 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 hole which is connected to the ring groove when the metering plunger 14 moves to a predetermined position. A cut-off port is formed and the main injection cut-off port is connected to the upstream side of the check valve.

Moreover, in the unit injector 1o mentioned above,
Although the plunger 26 has been described as having a roadside curve shape and being formed in the vertical and lateral parts of the valve body 11, the plunger 26 is formed in a straight line inside the lateral part. Anything you do is fine.

Of course, the bending angle of the valve body 11 may be arbitrary, and the valve body 11 may be bent so that the follower of the pumping plunger 12 is located on the cover 40 side when the valve body 11 is mounted on the cylinder head. It is formed by

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 is improved, the structure is simple, and it can be installed not only in large diesel engines but also in small diesel engines without restrictions on the position, allowing the overall engine to be further miniaturized. , become 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 silane, 13... Nozzle needle, 14...
... Metering granger, 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... Solenoid valve, 21... Needle spindle dere, 22...
...pulp sea), 23.24...spout, 25...
・Fuel reservoir, 26...Plunger dere, 30...
Needle spring, 3z...Pumping chamber, 35...Valve spring, 38...Cam
Shaft, 39...cam. Patent applicant Hino Motors Co., Ltd. Nippondenso Co., Ltd.

Claims (1)

[Claims] A needle spindle bore with a valve seat and a plurality of orifices;
A bent valve body has a plunger and a bonnet that communicate with the fuel reservoir in the bore, and a camshaft that is arranged to be able to reciprocate and slide in the syringe and is connected to a camshaft that is driven by a diesel engine. A cam attached to the valve
The pumping gland is forced into its plunger bore against a spring, and its needle spindle is fitted with a nozzle needle so that it is seated in its valve seat by a needle spring. , cooperating with its pumping plant to form a pumping chamber within its gland bore;
a metering plunger slidably fitted in a floating manner within the granger bore; - a fuel pump port formed in the valve body to communicate with the fuel reservoir of the needle spindle bore; , a fuel tank port opening in the plunger bore to be opened and closed by the pumping plunger, and a fuel tank port in a direction away from the nozzle;
an initial injection cut-off port opened in the gland bore at a predetermined distance from the port; and a main injection cut-off port opened in the plunger bore to be opened and closed by the metering plunger. an off port and a cut formed in the pumping granger to communicate the pumping chamber with the first stage injection cutoff port after the fuel tank port is closed by the pumping plunger; A unit injector used in a diesel engine that 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.