JPS61164044A - Fuel injection device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To dispense with an intake port and others for exclusively taking in fuel by opening and closing through a needle valve a fuel path of a pressure changing chamber in a spool communicating to a pressure chamber pressurized by the operation of a plunger and connecting a spill path to a communicating path for conducting a fuel path to a low pressure chamber of a pump. CONSTITUTION:A distribution type injection pump 1 pressurizes fuel in a pressure chamber 50 by the operation of a plunger 11 synchronized with an engine and supplies fuel into an injection nozzle 2 through a cut-out groove 12, discharge port, delivery valve 60, etc. Then, a spool 120 formed in the interior with a pressure changing chamber 150 communicating to the pressure chamber 50 through a throttle 121 is disposed to move toward and away from the pressure chamber 50 so that a fuel path 113 provided in said chamber 150 is opened and closed by a needle valve 110. The fuel path 113 communicates to a low pressure chamber 15 of a pump through a communication path 114 to which a spill path for releasing fuel in the pressure chamber 50 communicates, while this spill path is formed between both said chamber and spool when the spool 120 is spaced from the pressure chamber 50.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device for reducing fuel pressure in a pressure chamber for stopping fuel supply to a fuel injection nozzle. This invention relates to a type of fuel injection device whose mechanism is operated by a solenoid valve.

[Conventional technology]

Conventionally, in a fuel injection device for an internal combustion engine, fuel is sucked from a pump chamber into a pressure chamber by actuation of a plunger, the fuel in this pressure chamber is pressurized and supplied under high pressure to a fuel injection nozzle for injection, and then injection is stopped. A fuel injection device is known in which a spill passage communicating with the pressure chamber is sometimes opened to reduce the fuel pressure within the pressure chamber.

[Problem that the invention seeks to solve]

In the above-mentioned conventional device, when sucking the fuel in the pressure chamber, it is necessary to provide a suction port dedicated to sucking the fuel near the suction port of the plunger. It is also necessary to install a fuel cut solenoid to control fuel intake from this intake port.

The present invention aims to provide a fuel injection device with a simple structure that eliminates the need for a suction port dedicated to fuel suction and a fuel cut solenoid as described above.

[Means for solving problems]

According to the present invention, the above problem is solved by a pressure chamber that sucks fuel from a pump low pressure chamber by actuation of a plunger and supplies the fuel to an injection nozzle under high pressure, and a pressure chamber that is arranged so as to be able to come into contact with and separate from the pressure chamber. a spool formed in the spool, a variable pressure chamber formed in the variable pressure chamber, a needle valve for opening and closing a fuel passage provided in the variable pressure chamber, and an electromagnetic valve for controlling the opening and closing of the needle valve; The variable pressure chamber communicates with the spool through a throttle, and a communication passage is provided to communicate the fuel passage of the variable pressure chamber, which is opened and closed by the needle valve, with the pump low pressure chamber, and the pressure chamber and the spool are connected to each other. This problem is solved by providing a spill passage in between which allows the fuel in the pressure chamber to escape when the two are separated, and configuring a fuel injection device in which the spill passage is connected to the communicating passage that communicates with the pump low pressure chamber. be able to.

〔Example〕

The structure of an embodiment of the present invention, together with its operation, will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.

The distribution pump, designated in its entirety by l, is equipped with a high-speed solenoid valve 100 with a biloft mechanism for metering the fuel quantity. A plunger 11 is driven by an engine (not shown), and rotates and reciprocates in synchronization with two rotations of the engine.

When the notch groove 12 of the plunger 11 and the discharge port 31 of the cylinder 30 are electrically connected, it is the discharge stroke, and the plunger 11
moves to the right in the figure, and moves the fuel from the pressure chamber 50 to the notched groove 12. Fuel is sent to the injection nozzle 2 via the discharge port 31 and into the high pressure line 51 from the delivery valve 60 .

A distance piece 14 is provided adjacent to the pressure chamber 50.
A spool 120 abutted by a spring 160 is adjacent to this distance piece 140, and a variable pressure chamber 150 is formed within this spool 120. The transformation chamber 150 has a passage 122 provided with a throttle 121.
One end thereof communicates with the pressure chamber 50, and the other end is covered with a sheet 111. A fuel passage 113 is provided in the center of the seat 111, and this fuel passage 11
The tip of a needle valve 110 is inserted into the inside of the needle valve 3 . The needle valve 110 is pressed to the left in the figure by a spring 112 and constantly contacts the seat 111 to close off the fuel passage 113. 170 is an electromagnetic coil of the electromagnetic valve 100. The fuel passage 113 communicates with a fuel passage 180 that communicates with the pump low pressure chamber 15 via a communication passage 114 .

A liner 130 is disposed around the outer periphery of the spool 120, and the liner 130 is provided with an opening 131, which is connected to the aforementioned 114.

During the fuel discharge stroke due to rightward movement of the plunger 11, the needle valve 110 of the solenoid valve 100 is moved by the spring 1.
12 on the seat 111, and the fuel pressure is the same in the pressure chamber 50 and the variable pressure chamber 150 through the throttle 121 of the spool 120. distance piece 140
Since the cross-sectional area of the opening 141 is smaller than the cross-sectional area of the spool 120, the difference in the pressing force exerted on the spool 120 and the force of the spring 160 causes the spool 120 to be seated on the distance piece 140, and the fuel does not escape anywhere.

When adjusting the required injection amount, when the coil 170 of the solenoid valve 100 is energized, the needle valve 110 moves away from the seat 111 and opens the fuel passage 113 of the seat 111, causing pilot spill. At this time, the pressure in the variable pressure chamber 150 decreases, and a pressure difference occurs before and after the throttle 121 of the spool 120, so the spool 120 moves to the right in the figure.

At this time, the fuel in the pressure chamber 50 flows through the opening 13 of the liner 130.
1, and returns to the pump low pressure chamber 15 via a communication passage 114° and a fuel passage 180. During this stroke, fuel injection from the injection nozzle 2 ends.

During the fuel intake stroke, the plunger 11 moves to the left in the figure, thereby creating negative pressure in the pressure chamber 50 and variable pressure chamber 150. When the coil 170 is energized at this time, the needle valve 110 is separated from the seat 111, so the fuel from the pump low pressure chamber 15 passes between the needle valve 110 and the seat 111, passes through the throttle 121, Pressure chamber 5
0. Since the suction stroke takes a longer time than the spill stroke, there is no problem in sucking the fuel through the throttle 121.

FIG. 2 is a graph showing the fuel injection stroke of the above embodiment, and as shown in the figure, when the coil 170 is energized from the spill start time (i) to the fuel compression stroke (ii),
In the conventional device, there are two channels, a fuel intake passage and a fuel return passage.
What used to require two passages can be reduced to one fuel passage. Furthermore, in the distribution pump 1 equipped with the normally closed type electromagnetic valve 100 in which the needle valve 110 is always closed as shown in this embodiment, fuel injection is not performed unless the needle valve 110 is energized. I can't go there either. Therefore, safety is extremely high, and the fuel cut solenoid that was conventionally required can be omitted.

Furthermore, the suction notch groove that was conventionally formed in the VE pump plunger can be eliminated, and the structure of the plunger can also be simplified.

As described above, by sucking fuel from between the needle valve 110 and the seat ILL, a fuel suction passage and a fuel cut solenoid are not required, and the structure of the plunger is also simplified, making the fuel injection pump simple and compact. Moreover, it can be made highly safe.

A second embodiment of the present invention will be described with reference to FIG.

The main difference between the second embodiment and the first embodiment is that the second embodiment is different from the first embodiment.
In the embodiment, a normally closed type electromagnetic valve 100 that always closes the needle valve 110 is used, whereas in the second embodiment, a normally oven type electromagnetic valve 200 that always leaves the needle valve open is used. This is the point.

The normally open type solenoid valve 200 energizes the coil 270 and closes the needle valve 210 before entering the discharge stroke.
seat on the seat 211 to prevent fuel from spilling. When electricity is terminated at an arbitrary time, fuel is spilled and fuel injection is terminated. Since electricity is not applied during the suction stroke, the fuel in the pump low pressure chamber 15 flows through the fuel passage 280 and the communication passage 214.
, between the needle valve 210 and the seat 211, and through the throttle 221 of the spool 220, and are sucked into the pressure chamber 50.

Therefore, there is no need for a fuel intake passage, which was necessary in the conventional device.

FIG. 4 is a graph showing the fuel injection stroke of the second embodiment, and as is clear from the graph, the relationship between the on/off of the energization signal, the plunger lift, and the injection waveform is reversed from that in FIG. There is.

A third embodiment of the present invention will be described with reference to FIG.

The third embodiment corresponds to the first embodiment in which a check valve 400 is interposed in the spill passage.

This check valve 400 is connected to a passage 322 in the spool 320.
and the liner opening 331.

During the suction stroke, the plunger 11 moves to the left in the figure, and the pressure chamber 50 becomes negative pressure. At this time, fuel from the pump low pressure chamber 15 is sucked into the pressure chamber 50 through the fuel passage 380, the communication passage 314, and the check valve 400.

During the discharge stroke, the hard ball 410 of the check valve 400 is seated on the seat portion 420, and the needle valve 310 is seated on the seat 311, so that fuel does not spill.

When the coil 370 is energized, the needle valve 310 separates from the seat 311 and the spool 320 opens, causing the aperture 321 to open.
The fuel is spilled through the hole and fuel injection ends.

At this time, since the pressure in the variable pressure chamber 350 is higher than that in the pump low pressure chamber I5, the hard ball 410 of the check valve 400 is seated on the seat portion 420 due to the pressure difference and the spring 430.

Therefore, the function of the solenoid valve 300 is not obstructed (the fuel intake passage can be omitted).

〔Effect of the invention〕

As described above, the present invention sucks fuel into the pressure chamber through the solenoid valve installation part, so the special passage for fuel suction that is conventionally required can be omitted, and the plunger has a notch for suction. Since no grooves are required, it is simple, and therefore the structure of the injection pump can be simplified and made smaller.

Also, if a normally closed type solenoid valve is used,
Since no fuel is supplied when the key is off, the fuel cut solenoid can also be eliminated, making the system even simpler and safer.

Also, if a normally open type solenoid valve is used,
Since there is no fuel injection unless energization is applied, it is possible to create a small injection pump that is also highly safe.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the first embodiment of the present invention, FIG. 2 is a graph showing the operational relationship between the plunger, the electromagnetic valve, and the injection nozzle in the same embodiment, and FIG. 3 is the second embodiment of the present invention. FIG. 4 is a graph showing the operational relationship between the plunger, the electromagnetic valve, and the injection nozzle in the embodiment, and FIG. 5 is a longitudinal sectional view of the third embodiment of the present invention. ■... Distribution type pump, 2... Injection nozzle, 11... Plunger, 15... Pump low pressure chamber, 50... Pressure chamber, 100.200,
300...Solenoid valve, 110, 210.310...Needle pulp, 111, 211. 311... Seat, 113... Fuel passage, 114, 214.
314...Communication path, 120, 220.320...
・Spool, 121, 221. 321...Aperture,
122, 322...Aisle, 130.
...Liner, 131, 331...Opening, 1
50.350...pressure chamber, 170, 270. 37
0...Electromagnetic coil, 400...Check valve,
410...hard ball, 420...seat part,
430...Spring.

Claims (4)

[Claims] 1. A pressure chamber that sucks fuel from a pump low pressure chamber by actuation of a plunger and supplies the fuel to an injection nozzle under high pressure, a spool that is disposed so as to be able to come into contact with and separate from the pressure chamber, and a variable pressure formed in the spool. a needle valve that opens and closes a fuel passage provided in the variable pressure chamber, and an electromagnetic valve that controls the opening and closing of the needle valve, and the pressure chamber and the variable pressure chamber are connected to each other through a throttle provided in the spool. A communication passage is provided between the pressure chamber and the spool to communicate the fuel passage of the variable pressure chamber, which is opened and closed by the needle valve, with the pump low pressure chamber, and between the pressure chamber and the spool, when the two are separated, A fuel injection device for an internal combustion engine, characterized in that a spill passage for escaping fuel is provided, and the spill passage is connected to the communication passage communicating with the pump low pressure chamber. 2. 2. The fuel injection device according to claim 1, wherein said needle valve is always closed and opened only when said electromagnetic valve is actuated. 3. Claim 2: A check valve that opens only when fuel is sucked into the pressure chamber is interposed in the spill passage.
The fuel injection device described in Section 1. 4. 2. The fuel injection device according to claim 1, wherein the needle valve is always open and closed only when the electromagnetic valve is activated.