JPS58190565A - Fuel injection device - Google Patents

Abstract

PURPOSE:To improve combustion performance, by equipping and accumulative pressure piston appearing in a compression chamber, in which fuel is pressurized by a shuttle moved plunger, and ensuring prescribed fuel injection pressure even at low revolution. CONSTITUTION:A holder 13 having a fuel outlet passage 14 is screwed to a body 11 having an oil reservoir 12 communicated to a feed pump, and a bridging cage 15, spring cage 16 and an accumulative pressure piece 17 are inserted into an internal hole of said holder 13 to close the hole by a cylinder 18 fixed to the body 11. A plunger 23 is slidably inserted into a cylinder hole 19 of the cylinder 18 to perform shuttle motion by rotation of a cam 30. While an accumulative pressure piston 33 is slidably housed in a hole 32 provided to the piece 17 and said piston 33 is urged downward by a spring 34. Then a device is constituted such that pressurized fuel by a lift of the plunger 23 is fed to the passage 14 through an outlet port 21 and passage 22 from a compression chamber 24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device, for example a fuel injection device for supplying fuel to a fuel injection nozzle of an internal combustion engine.

As a conventional fuel injection device, for example, the one described in "ED-3D Series Diesel Engine" (published by Nissan Motor Co., Ltd.) is known, and the configuration of this fuel injection device is shown in Figs. The explanation will be based on (f). 1 is a plunger barrel, and this plunger barrel 1 is formed with a cylinder hole 2, a suction port 3 communicating with the cylinder hole 2, and an outlet boat 4. The suction port 3 communicates with an oil reservoir filled with fuel pumped from a feed pump, and the outlet boat 4 communicates with an injection valve (not shown). A plunger 5 is slidably housed in the cylinder hole 2, and the plunger +5 slides in the direction of the arrow A by a cam (not shown), and in the opposite direction to the arrow A by the elastic force of the spring. . A passage 6 whose one end opens to the end face of the plunger 5 and an inclined groove 7 that communicates the outer extrusion of the plunger 5 with the passage 6 are formed in the plunger 5, and the inclined groove 7 can communicate with the suction port 3. It is. A delivery valve 8 is disposed at the outlet port 4, and the delivery valve 8 is constantly pressed into the outlet boat 4 by a spring 9. A delivery valve stopper 10 is formed on the plunger barrel l, and the lift amount of the delivery valve 8 mentioned above is regulated by the stopper lO.

In such a fuel injection device, when the plunger 5 slides in the direction of the arrow, fuel is supplied from the suction port 3 to the cylinder hole 2 (Fig. 1 (a)), and when the plunger 5 slides in the direction of the arrow, fuel is supplied to the cylinder hole 2. When the plunger 5 closes the suction port 3, the fuel in the suction port 2 flows out from the suction port 3.

(FIG. 1(b)) When the suction port 3 is closed by the plunge +5 (FIG. 1(C)), the fuel in the cylinder hole 2 begins to be fed under pressure from the outlet port 4 and is injected from the injection valve. The delivery valve 8 is pushed open until the inclined groove 7 of the plunger 5 communicates with the suction port 3 (see FIG. 1(d)).
), pressurized fuel is supplied to the injector, but the inclined groove 7
When the fuel in the cylinder hole 2 is communicated with the suction port 3, the fuel in the cylinder hole 2 is no longer fed under pressure (Fig. 1(e)), and the fuel is transferred from the cylinder hole 2 and the outlet port 4 to the injector via the passage 6 and the inclined groove 7 to the suction port. Note that in such a fuel injection device, when the plunger 5 is rotated within the cylinder hole 2, the communication position between the inclined groove 7 and the intake port 3 is changed, and the injection amount is changed. is changed.

However, in such a conventional fuel injection device, as soon as the intake port 3 is closed by the plunge +5, the fuel in the cylinder hole 2 is force-fed, so when the injection amount is small or the cam is rotated at a low speed, When this happens, the injection pressure decreases, making it impossible to atomize the fuel injected from the injection valve, resulting in poor fuel efficiency and smoke and N in the exhaust gas.

There was a problem that the concentration of X and unburned hydrocarbons became high.

The present invention was made in view of these conventional problems, and includes a cylinder in which a suction port and an outlet boat are formed that communicate with the cylinder hole, and a cylinder that is slidably housed in the cylinder hole. Together with the cylinder, a compression chamber is defined through which fuel flows in and out.The first position, where the volume of the compression chamber is maximized by the cam, and the second position, where the volume of the compression chamber is the minimum, are defined by the cam.
A pressure accumulating piston is provided in the cylinder, with one end facing the compression chamber and the other end biased toward the compression chamber by a spring, and the plunger can be communicated with the suction port and the outlet port. a first port,
A second port that can communicate with the suction port and a passage that communicates the first port and the second port with the compression chamber are formed, and when the plunger is in the first position, the compression chamber and the outlet port and the first port communicate with each other. When the ports reach each other and the plunger slides a certain distance from the first position to the second position, the compression chamber and the outlet port and the first port and the suction port are respectively shut off, the fuel in the compression chamber is pressurized, and the plunger is opened. When the plunger further slides a certain distance, the first port communicates with the outlet port, and the pressurized fuel in the compression chamber is discharged to the outlet port via the passage and the first port, and when the plunger further slides a certain distance, it reaches the second position. When the compression chamber becomes the passage and the second
The outlet port connects the first port to the passageway and the second port via the port.
It is an object of the present invention to solve the above-mentioned problems by providing a fuel injection device which communicates with suction ports through ports and is capable of discharging pressurized fuel into a suction boat.

Hereinafter, this invention will be explained based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention, and the configuration will be explained first. 11 is a body of a fuel injection device, and an oil reservoir 12 is formed in this body 11 and communicates with a feed pump (not shown).

A holder 13 is screwed onto the body 11.
3 has a fuel outlet passage 14 and a hole formed therein.

The fuel outlet passage communicates with an injection valve of an internal combustion engine (not shown). A transition cage 15, a substantially cylindrical spring cage 16, and a pressure accumulating piece 17 are inserted into this hole, and the hole of the holder 13 is closed by a cylinder 18 fixed to the body 11. A cylinder hole 19 is formed in the cylinder 18, and a suction boat 20 formed in the center of the cylinder 18 communicates the oil reservoir 12 with the cylinder hole 19. An outlet port 21 is formed at the end of the cylinder 18 on the pressure accumulating piece 17 side, and this outlet port 21 communicates the cylinder hole 19 and the connecting passage n. The connecting passage n includes the pressure accumulating piece 17 and the spring cage 16.
and is formed in the crossing cage 15, and the outlet port 2
1 and a fuel outlet passage 14 are communicated with each other. A plunger device is slidably housed in the aforementioned cylinder hole 19.
A compression chamber 24 is defined by the cylinder 18 and the plunger device.

A passage 5 extending in the axial direction is formed in the plunger device, and one end of this passage 5 is opened at the inverted end surface of the pressure accumulating piece 17 of the plunger device.

The other end of the passage 5 communicates with a plunger lead formed obliquely on the outer periphery of the plunger device, and the middle part of the passage 5 communicates with an annular pressure feeding group 2 formed on the outer periphery of the plunger 23.
It is connected to 7. The end of the plunger on the side opposite to the pressure accumulation piece 17 protrudes from the body 11, and a spring 29 is used to engage the retainer 4 fixed to the end and the cylinder 18.
is interposed. As a result, the plunger device is constantly pressed against the cam by the elastic force of spring 4.
The cam shaft is driven by a timing gear of an internal combustion engine (not shown) via a camshaft 31. A hole is formed in the aforementioned pressure accumulating piece 17, and a pressure accumulating piston is slidably housed in this hole 32. This pressure accumulating piston wing is always biased by a spring 34 housed in the spring cage 16 in the direction in which the pressure accumulating piston is inserted into the hole wing.
3 is housed in the spring cage 16, and the crossing cage 1
It can come into contact with a stopper fixed to 5. An oil relief hole is formed in the spring cage 16, and the hole returns fuel leaking into the spring cage 16 to the oil sump 12.

Next, the effect will be explained. When the internal combustion engine operates, the plunger device first slides in the direction of the arrow by the spring 4. As a result, the plunger device is in the first position in which the compression chamber 24 has a maximum volume, and the compression chamber 24 is supplied with fuel from the oil sump 12 via the suction boat 20, the pumping group n and the passage 5. Next, when the plunger path slides in the direction of arrow B according to the rotation of the cam, the pumping group R remains at the suction port for a certain distance from the first position, as shown in FIG. 3(a). compression chamber U because it communicates with
The fuel in the passage δ, the pumping group r and the suction port) 2
0 to the oil sump 12. When the plunger device further slides in the direction of arrow B and suction port application and pressure feeding group n are cut off as shown in FIG. move against. As a result, the fuel in the compression chamber U increases to a predetermined pressure. Immediately before the accumulating piston contacts the stopper A, the pressure feeding group R exits as shown in FIG. 3(C). It communicates with the port 21, and as the plunger path slides in the direction of the arrow B, the pressurized fuel in the compression chamber U passes through the passage 6 and the pumping group r, as shown in FIG. 3(d). It is discharged to the exit port) 21. This pressurized fuel is transferred to the connecting passage 22# and the fuel outlet passage 1.
4 to an injection valve (not shown). While the fuel is being pumped, the pressure accumulating piston blades also move in the direction opposite to arrow B, so the injection pressure can be maintained at a high value. In this way, since the fuel is supplied to the injection valve after increasing the pressure to a predetermined pressure, the injection pressure can be maintained high even when the injection amount is small or when the cam (9) is rotated at low speed, and the atomization of the fuel can be achieved. can.

Furthermore, since the pressurized fuel is sent to the injection valve, a large amount of fuel can be supplied in a short period of time, and the nozzle area of the injection valve can be reduced. As a result, atomization of the fuel is further promoted. Therefore, fuel efficiency is improved and smoke and N in exhaust gas are reduced.
The concentration of Ox and unburned hydrocarbons decreases. In addition, in order to send pressurized fuel to the injection port, it is possible to reduce the sliding speed of the plunger blade, which eliminates the need to make the cam nodule as steep as in the conventional case. Durability can be improved. The plunger arm further slides in the direction of arrow B, and the plunger lead reaches the suction port 20 as shown in FIG. As shown in FIG. 1, the pressurized fuel in the compression chamber u1, the continuous passage n, the fuel outlet passage 14, etc. is discharged to the oil sump 12. That is, the pressurized fuel in the compression chamber U is discharged to the oil sump 12 via the passage 5 and the plunger lead pressure and suction port 20, and the pressurized fuel in the connecting passage n etc. is discharged to the oil sump 12 through the outlet port 21. JE
It is discharged into the oil sump 12 via the feed group n, the passage δ and the suction port) 20. When the plunger is thus in position 182, which minimizes the volume of the compression chamber, the plunger n slides in the direction opposite to arrow B and repeats the operation described above.

Note that the elastic force of the spring is desirably selected to a value that prevents the accumulating piston 33 from colliding with the stopper.Also, a conventional delivery valve 8 may be provided in the outlet port 21, and the pre-delivery valve 8 is used to prevent irregular injection. It is effective in preventing.

As explained above, according to the present invention, a fuel injection device is slidably housed in a cylinder in which a cylinder hole is formed with a suction port and an outlet port that communicate with the cylinder hole. and a plunger that defines a compression chamber in which fuel flows in and out together with the cylinder, and slides by a cam from a first position where the volume of the compression chamber is maximized to a second position where the volume of the compression chamber is minimized, The cylinder is provided with a pressure accumulating piston whose one end faces the compression chamber and whose other end is biased toward the compression chamber by a spring, and which can communicate with the suction port and a first boat which can communicate with the suction port and the outlet port during plunging. a second port, and a passage communicating the first boat and the second port with the compression chamber, and when the plunger is in the first position, the compression chamber and the outlet port and the first boat and the suction port communicate with each other. When the plunger slides a certain distance from the first position to the second position, the compression chamber, the outlet boat, and the first
The boat and the suction port are each shut off to pressurize the fuel in the compression chamber, and when the plunger slides a certain distance further, the first boat communicates with the outlet port and the pressurized fuel in the compression chamber flows through the passage and the first boat. When the plunger is further slid a certain distance to the 12 position, the compression chamber is connected to the passage and the second port, and the outlet port is connected to the first boat, the passage and the second port. Since the pressurized fuel can be discharged into the suction port by communicating with the suction port, it is possible to promote fine particle formation of the injected fuel, reducing the concentration of smoke, NOx, and unburned hydrocarbons in the exhaust gas. The effect of creating a wall can be obtained.

[Brief explanation of the drawing]

1(a) to 1(f) are schematic front sectional views of a conventional fuel injection device, FIG. 2 is a front sectional view showing an embodiment of the fuel injection device according to the present invention, and FIGS. 3(a) to 3(f) are schematic front sectional views of a conventional fuel injection device. (f) is an explanatory diagram of the operation of the fuel injection device shown in FIG. 2. 18- ・- cylinder, 19- ・- cylinder hole,
Addition: Suction port, 21: Exit port, 23: Plunger, Sue: Exit boat, 6: -Passage, A... -・2nd port, r・-----1st port, vane-1 pressure chamber (hole),
4 33...m-accumulator piston. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Ugagun Part 5 Figure 1 (0)
(b) Figure 7 Figure 7 Figure 2 14 Figure 3 (a) 4 Figure 3 (b) 4 Figure 3 (C) 4 Figure 3 (d) to Figure 3 (e) 4

Claims (1)

[Claims] A cylinder is formed with a cylinder hole and a suction port and an outlet port that reach the cylinder hole, and a cam that is slidably housed in the cylinder hole and defines a compression chamber through which fuel flows in and out together with the cylinder and is operated by the engine. A fuel injector having a plunger that slides from a first position where the volume of the compression chamber is maximum to a second position where the volume of the compression chamber is minimum, one end facing into the compression chamber and the other end facing into the compression chamber. EE
A pressure accumulating piston that is biased by a spring toward the m-chamber side is provided in the cylinder, and a first port that can communicate with the suction port and the outlet port during plunging, a second port that can communicate with the suction port, the first port, and a passage communicating the second port with the compression chamber, and when the plunger is in the first position, the compression chamber communicates with the outlet port, and the first port communicates with the suction port, and during the plunge, from the first position to the second When the plunger slides a certain distance toward the plunger position, the compression chamber and the outlet port and the first port and the suction port are respectively shut off, and the fuel in the compression chamber is pressurized. When the plunger slides a certain distance further, the first port communicates with the outlet port. The pressurized fuel in the compression chamber is then discharged to the outlet port through the passage and the first port, and when the plunger is further slid a certain distance to the second position, the compression chamber is discharged through the passage and the second port. ,
A fuel injection device characterized in that the outlet port communicates with a suction port through a first port, a passage, and a second port, respectively, so that pressurized fuel can be discharged to the suction port.