JPH0226705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for use in a diesel engine equipped with a unit injector.

Generally, unit injectors have been configured to be mounted directly on the cylinder head of a diesel engine and driven by the cam shaft of the diesel engine to inject fuel.

In particular, unlike in-line fuel injection pumps or distributed fuel injection pumps, this type of unit injector is installed directly on the cylinder head of a diesel engine without using a high-pressure injection pipe, so it Pressure loss is small, injection delay is prevented, and the end of injection, that is, the fuel runs out, is done well.

However, the fuel injection pressure in such a unit injector is determined by the pressure receiving area of the plunger, which is arranged to be able to slide back and forth to compress the fuel in the injection pump chamber of the unit injector.
In addition, since the injection pressure is determined by the sliding stroke of the plunger, there is a limit to how high the injection pressure can be, and the fuel injection rate is relatively low, making it difficult to improve the fuel consumption rate.

The object and problem of this invention is to improve the fuel injection amount and timing of fuel injection, increase the fuel injection pressure, increase the fuel injection rate, and improve the injection consumption rate. The purpose is to provide equipment.

In relation to the above objects and problems, the fuel injection device used in the diesel engine of the present invention includes a metering plunger bore, a pressure-feeding plunger bore connected to the metering plunger bore, and a metering plunger bore. A metering plunger that is slidably fitted in a bore to form an injection pump chamber; a metering plunger that is slidably fitted in a pressure-feeding plunger bore and cooperates with the metering plunger to form a pressure-feeding pump chamber; a pump port connected to the injection pump chamber, a nozzle/needle that opens and closes the nozzle, and a pressure pump that forms the injection pump according to the reciprocating motion of the pressure plunger. Spill intermittent into the chamber
port, on its metering plunger bore side,
A spill port opened to the pressure pump chamber,
And, depending on the reciprocating movement of the metering plunger,
a unit injector with a spill port connected to its injection pump chamber;
A fuel injection line connecting a port to a fuel tank and having a fuel feed pump, and a feed fuel solenoid located at either the pump port and the fuel injection line downstream of the fuel feed pump. A valve and a fuel pressure transmission pipe that connects its fuel tank side to a spill port opened to its pressure pump chamber, and a fuel pressure transmission pipe equipped with a fuel boost pump, and a spill port opened to its pressure pump chamber.
A boost fuel solenoid valve disposed on either side of the port and the fuel pressure transmission piping on the downstream side of the fuel boost pump, and a boost fuel solenoid valve disposed on either side of the fuel pressure transmission pipe downstream of the fuel boost pump, and connected to the pressure pump chamber in accordance with the reciprocating movement of the pressure plunger. Spill piping connects the spill port and its fuel pressure transmission piping upstream of the boost fuel solenoid valve, and depending on the operating conditions of the diesel engine,
The controller is configured to include a controller that controls these solenoid valves.

Hereinafter, specific examples of the fuel injection device used in the diesel engine according to the present invention will be explained.
This will be explained with reference to the drawings.

1 to 5 schematically show a specific example 10 of a fuel injection device used in a diesel engine according to the present invention.

The fuel injector 10 defines a nozzle, a pump port 25, a spill port 29, etc., a nozzle needle (not shown), a metering plunger 21,
A unit incorporating a pressure-feeding plunger 23, etc.
Injector 11, fuel injection piping 38, 39 that communicates its pump port 25 with fuel tank 37 and is equipped with fuel feed pump 12, and feed fuel solenoid valve 13 disposed in pump port 25; The spill port 29 and the upstream fuel injection line 38 of the fuel feed pump 12
and a fuel pressure transmission pipe 40, 42 equipped with a fuel boost pump 14, and a boost fuel solenoid valve 15 disposed in the fuel pressure transmission pipe 42.
and a controller 16 that respectively controls the solenoid valves 13 and 15 according to the engine operating conditions of the diesel engine.

The unit injector 11 is a valve
a needle spindle bore (not shown) having a seat (not shown) and a plurality of orifices (not shown) in a lower position and a fuel sump (not shown) in the needle spindle bore; valve bodies 17 each having a communicating plunger bore 18 in an upper position and fitted into its needle spindle bore so as to be seated in its valve seat by a needle spring (not shown); With a mated nozzle needle (not shown), the lower side of the plunger bore 18 so as to form an injection pump chamber 22 in its lower position in the plunger bore 18, i.e.
A metering plunger 21 is arranged in the metering plunger bore 19 so as to be able to slide back and forth, and the plunger
It is arranged to be reciprocally slidable in the upper side of the plunger bore 18 , that is, in the pressure-feeding plunger bore 20 , so as to form a pressure-feeding pump chamber 24 between the metering plunger 21 and the bore 18 . It is composed of a pressure feeding plunger 23 and the like.

The plunger in the valve body 17
The bore 18 has a metering plunger bore 19 formed with a predetermined inner diameter on the lower side, and a metering plunger bore 19 formed with a slightly larger inner diameter than the metering plunger bore 19 on the upper side.・Bore 19
The plunger bore 20 is eccentrically formed with respect to the plunger bore 18.
is connected to the fuel reservoir of the needle spindle bore described above via a fuel passage 35 formed on the lower side of the valve body 17.

The lower part of the metering plunger bore 19 is
Furthermore, it is connected via a fuel passage 26 to a pump port 25 opened on one side above the valve body 17.

In addition, a spill valve is located below the metering plunger bore 19 and on the fuel passage 26 side.
A port 27 is formed and the spill port 27
is connected to the fuel passage 26.

Near the top of the metering plunger bore 19,
At a position opposite to the fuel passage 26, a spill port 30 is formed in the valve body 17, which is connected to and connected to the injection pump chamber 22 in accordance with the reciprocation of the metering plunger 21.

Also, at the lower side of the pressure-feeding plunger bore 20, that is, the metering plunger bore 19
On the side opposite to the fuel passage 26, a spill port 29 opened into the pressure pump chamber 24 was formed in the valve body 17.

Further, at a position substantially in the center of the pressure-feeding plunger bore 20 and at a position opposite to the fuel passage 26, there is a spill pipe that is connected to and connected to the pressure-feeding pump chamber 24 in accordance with the reciprocation of the pressure-feeding plunger 23.
A port 28 is formed in the valve body 17.

Of course, the valve body 17 is of a split type so that it can be split at a predetermined position in order to facilitate the assembly of the nozzle needle, metering plunger 21, and pumping plunger 23. It is desirable that the

The metering plunger 21 is connected to the valve body 1
7 on the lower side of its plunger bore 18 , i.e. in its metering plunger bore 19 so as to be reciprocally slidable.

In that way, the metering plunger bore 1
9 , the injection pump chamber 22 is formed on the lower side of the metering plunger bore 19 .

Of course, the injection pump chamber 22 is in communication with the pump port 25 via the fuel passage 26 and with the fuel sump of the needle spindle bore via the fuel passage 35, respectively.

Also, in the fuel passage 26 communicating with the pump port 25, the injection pump chamber 22
A check valve 36 is arranged on the upstream side of the injection pump chamber 22 to prevent backflow of fuel from the injection pump chamber 22 to the pump port 25 side.

Further, a ring-shaped spill groove 31 is formed approximately at the center of the metering plunger 21.
The spill groove 31 is communicated with the injection pump chamber 22 via a spill communication passage 32 opened at the lower end face of the metering plunger 21 .

The spill groove 31 is connected to the metering plunger 21.
When the dosing plunger is forced into position within the dosing plunger bore 19, it communicates with its spill port 27 formed in the dosing plunger bore 19.

Of course, in that way, the metering plunger 2
When the spill groove 31 of No. 1 is connected to its spill port 27, its injection pump chamber 22 is connected to the upstream side of the above-mentioned check valve 36 in the fuel passage 26 that is connected to its pump port 25. Ru.

Therefore, the fuel in the injection pump chamber 22 is placed in a state where it can escape to the fuel passage 26 side, and the end of fuel injection is determined by such escape of fuel.

Also, when the metering plunger 21 is positioned upwardly within the metering plunger bore 19, the spill port 30 formed above the metering plunger bore 19 is located above the metering plunger bore 19. , but when its metering plunger 21 is pushed into position, its spill port 30 is opened, as described above.

The pressure-feeding plunger 23 is connected to the valve body 1
It is reciprocally slidably arranged on the upper side of the plunger bore 18 at 7, i.e. in its pumping plunger bore 20.

In that way, the pumping plunger bore 2
0, the pressure pump chamber 24 is formed on the lower side of the pressure plunger bore 20, in other words between it and the metering plunger 21.

A ring-shaped spill groove 33 is formed at a substantially central position of the pressure-feeding plunger 23, and the spill groove 33 allows the pressure-feeding plunger 23 to be It is connected to the pump room 24.

The spill groove 33 is connected to the pumping plunger 23.
When the pump is forced into position within the pumping plunger bore 20, it communicates with its spill port 28 formed in the pumping plunger bore 20.

Of course, the upper end of the pressure-feeding plunger 23 is crowned with a follower 44 that protrudes from the upper end surface of the valve body 17, and between the flange of the follower 44 and the valve body 17, a valve spring ( (not shown) are arranged.

The unit injector 11 configured as described above has a nozzle contained within the combustion chamber.
It is attached to the cylinder head (not shown) of the diesel engine.

Of course, the unit injector 11 is mounted on the cylinder head such that the tip of the rocker arm 46, which is driven by the diesel engine's camshaft 45, contacts the top surface of the follower 44.

The fuel injection lines 38, 39 connect the pump port 25 of the unit injector 11 to the fuel tank 37, which includes the fuel feed pump 12.

Of course, the fuel feed pump 12 is driven by the diesel engine, and the supply port 50 is connected to the pump port 25 of the unit injector 11, and the suction port 51 is connected to the fuel tank 37. There is.

Further, in the fuel injection pipe 39, there is a surge valve on the downstream side of the fuel feed pump 12.
A tank 47, a fuel filter 48, and an acumulator 49 are respectively arranged.

The feed fuel solenoid valve 13 is configured to supply and shut off fuel sent to the pump port 25 of the unit injector 11.
That is, it is attached to the pump port 25 so as to meter the amount of fuel sent to the injection pump chamber 22 of the unit injector 11.

The feed fuel solenoid valve 13 is controlled by a controller 16, which will be described later, according to the engine operating conditions of the diesel engine.

The fuel pressure transmission pipes 40 and 42 connect the spill port 29 of the unit injector 11 and the upstream fuel injection pipe 38 of the fuel feed pump 12, and are equipped with the fuel boost pump 14. There is.

Of course, the fuel boost pump 14 is driven by a diesel engine, and the supply port 52 is connected to the spill port 29 of the unit injector 11, and the suction port 53 is connected to the fuel tank 37. There is.

Further, the spill port 28 of the unit injector 11 is connected to the fuel pressure transmission pipe 40 via a spill pipe 41.

The boost fuel solenoid valve 15 is connected to the spill port 29 side, that is, the fuel pressure Transmission piping 42
It is set in.

The boost fuel solenoid valve 15 is controlled by a controller 16, which will be described later, according to engine operating conditions of the diesel engine.

The controller 16 receives signals from a rotation speed sensor (not shown), a load sensor (not shown), a fuel temperature sensor (not shown), an atmospheric pressure sensor (not shown), etc. of the diesel engine, and feeds.・Depending on the trigger pulse etc. from the back circuit,
It controls the opening and closing of the solenoid valves 13 and 15 on the injection side and the pressure feeding side, respectively, according to a preset fuel injection pattern, and mainly consists of an input and output circuit, a memory circuit, an arithmetic circuit, and a control circuit. has been done.

Next, the fuel injection device 1 configured as described above
To explain the operation of the diesel engine, when the diesel engine is operating, the cam shaft 45 is rotated, and the fuel feed and boost pumps 12, 14 are driven by the diesel engine. During metering, the feed and boost fuel solenoid valves 13 and 15 are opened, respectively, by an output signal from the controller 16.

That is, fuel from the fuel feed pump 12 is metered by the feed fuel solenoid valve 13, the metered fuel passes through the pump port 25 of the unit injector 11, and the metered fuel passes through the pump port 25 of the unit injector 11. It is sent to its injection pump chamber 22 through valve 36.

Of course, when metering such fuel, since the boost fuel solenoid valve 15 is open, the metering plunger 21 of the unit injector 11
is pushed upward by the metered fuel (see Figure 2).

Furthermore, when such fuel is metered, the rocker arm 46 rotates as the cam shaft 45 rotates, and the follower 44 is lifted upward by the valve spring. , the pumping plunger 23 together with the follower 44 is lifted upwards.

Of course, after metering such fuel, the feed fuel solenoid valve 13 is closed by the controller 16.

Next, when fuel is pumped, the follower 44 is pushed in against the valve spring by the rotation of the rocker arm 46, and the pressure-feeding plunger 23 is pushed in the same way, but the boost fuel solenoid valve 15 is pushed in against its valve spring. Since it is opened by the output signal from the controller 16, the fuel in the pressure pump chamber 24 is released to the fuel boost pump 14 side (see FIG. 3).

Furthermore, when fuel is injected, the boost fuel solenoid valve 15 is closed by an output signal from the controller 16, and when the pressure-feeding plunger 23 is pushed in as described above, the pressure-feeding pump chamber 2
4 is compressed to high pressure, and the metering plunger 21 is pushed down by the compressed fuel (see FIG. 4).

That is, by pushing down the metering plunger 21 in this way, the fuel compressed to a high pressure in the injection pump chamber 22 is sent to the fuel reservoir via the fuel passage 35, and the nozzle needle is is lifted against its needle spring and fuel is injected.

Further, at the end of fuel injection, the spill groove 31 of the metering plunger 21 is connected to the spill port 27 of the metering plunger bore 19, and the spill port 3 of the metering plunger bore 19
0 is opened and communicated with its pressure pump chamber 24, and the spill groove 33 of its pressure plunger 23 is connected to the spill groove of its pressure plunger bore 20.
Port 28 is contacted (see FIG. 5).

That is, the fuel in the injection pump chamber 22 is released to the upstream side of the check valve 36 in the fuel passage 26, and the fuel in the pressure pump chamber 24 is released to the fuel tank 37 side, and the injection Since the pressure in the pump chamber 22 and the pressure pump chamber 24 decreases, fuel injection ends.

In the above-described operation, the feed and boost fuel solenoid valves 13 and 15 are controlled by the controller 16 based on a preset fuel injection pattern depending on the speed, load, fuel temperature, atmospheric pressure, etc. of the diesel engine. The boost fuel solenoid valve 15 on the pressure feeding side controls the spill fuel pressure according to engine speed, load, fuel temperature, etc. Therefore, the pressure inside the pressure pump chamber can be increased, or in other words, the fuel injection pressure can be increased.

As understood from the above, the fuel injection device used in the diesel engine of the present invention includes a fuel feed pump in which the fuel injection piping connects the pump port to the fuel tank, and the feed fuel solenoid valve includes: the pump port and the fuel injection piping downstream of the fuel feed pump, with the fuel pressure transmission piping opening into the pressure pump chamber on the metering plunger bore side of the unit injector. A fuel boost pump is provided with its fuel tank side connected to a spill port opened to the pressure pump chamber, and a boost fuel solenoid valve is connected to the spill port opened to the pressure pump chamber, and the downstream side of the fuel boost pump. A spill port and a boost fuel solenoid valve are arranged on either side of the fuel pressure transmission pipe of the unit injector, and the spill pipe is connected to and connected to the pressure pump chamber according to the reciprocation of the pressure plunger in the unit injector. The controller controls these solenoid valves according to the operating conditions of the diesel engine, so that the fuel injection amount and injection timing are appropriate, and in particular, the boost The fuel solenoid valve adjusts the fuel spill pressure in the pressure pump chamber to the engine speed, load,
It becomes possible to increase the pressure in the pressure pump chamber by controlling it according to the fuel temperature, etc. In other words, it becomes possible to increase the fuel injection pressure, improve the fuel consumption rate, and increase the pressure in the pressure pump chamber. The high-pressure fuel in the pump chamber is boosted by its spill piping.
It is allowed to escape to the discharge side of the pump and not directly to the fuel tank, thus preventing excessive circulation of fuel and suppressing wasteful consumption of engine power.
Be extremely practical.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a specific example of a fuel injection device used in a diesel engine of the present invention, and FIG. 2 is an overview of the fuel metering state of the unit injector in the fuel injection device shown in FIG. 1. 3 is a partial sectional view schematically showing the fuel pumping state of the unit injector shown in FIG. 2, and FIG. 4 is a partial sectional view of the unit injector shown in FIG. 2. FIG. 5 is a partial cross-sectional view schematically showing a fuel injection state, and FIG. 5 is a partial cross-sectional view schematically showing a fuel injection completion state of the unit injector shown in FIG. 11... Unit injector, 12... Fuel feed pump, 13... Feed fuel solenoid valve, 14... Fuel boost pump, 15... Boost fuel solenoid valve, 16... Controller, 21
... Metering plunger, 23 ... Pressure feeding plunger,
25... Pump port, 29... Spill port, 38, 39... Fuel injection piping, 40, 42...
...Fuel pressure transmission piping.

Claims (1)

[Claims] 1. A metering plunger bore 19, a pressure-feeding plunger bore 20 connected to the metering plunger bore 19, and an injection pump fitted in the metering plunger bore 19 so as to be slidable back and forth. a metering plunger 21 forming a chamber 22, fitted in its pumping plunger bore 20 so as to be slidable back and forth;
and a pressure-feeding plunger 23 that cooperates with the metering plunger 21 to form a pressure-feeding pump chamber 24, a pump port 25 connected to the injection pump chamber 22, a nozzle connected to the injection pump chamber 22,
A nozzle needle opens and closes the nozzle, a spill port 28 is connected to the pressure pump chamber 24 in response to the reciprocation of the pressure plunger 23, and a spill port 28 is connected to the pressure pump chamber 24 on the metering plunger bore 19 side. spill port 29 opened;
In response to the reciprocating movement of the metering plunger 21, the spill is intermittent in the injection pump chamber 22.
Unit injector 11 with port 30
and a fuel injection line 38, 39 connecting the pump port 25 to the fuel tank 37 and having a fuel feed pump 12; A feed fuel electromagnetic valve 13 disposed on either side of the injection pipe 39 and a fuel boost pump 14 are provided, with the fuel tank 37 side communicating with the spill port 29 opened to the pressure pump chamber 24. The transmission pipes 40 and 42, the spill port 29 opened to the pressure pump chamber 24, and the fuel boost pump 1
A boost fuel solenoid valve 15 disposed on either one of the fuel pressure transmission pipes 40 and 42 on the downstream side of the boost fuel solenoid valve 15.
and a spill communicating between the spill port 28 connected to and connected to the pressure pump chamber 24 and the fuel pressure transmission pipes 40 and 42 on the upstream side of the boost fuel electromagnetic valve 15 in accordance with the reciprocation of the pressure plunger 23. A fuel injection device used in a diesel engine, including a pipe 41 and a controller 16 that controls the electromagnetic valves 13 and 15 according to the operating conditions of the diesel engine.