JPS6157944B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed fuel injection device for a multi-cylinder internal combustion engine, and more particularly to a pump mechanism for pumping fuel in conjunction with the crankshaft of a multi-cylinder internal combustion engine, and a fuel injection device for pumping fuel from the pump mechanism. The present invention relates to a distribution type fuel injection device including a pressurization distribution mechanism that works in conjunction with the pump mechanism to pressurize and inject fuel into each cylinder sequentially.

In one conventional example of this type of distribution type fuel injection device, the above-mentioned pressure distribution mechanism includes a cylinder into which fuel is supplied from the pump mechanism via a pressure regulating valve means, and a cylinder provided inside the cylinder. and a plunger that moves in synchronization with the rotation of the internal combustion engine. Inside the plunger, holes are formed that open at the tip and side surfaces of the plunger inside the cylinder, while on the side wall of the cylinder, there are a plurality of holes each communicating with the cylinder via a valve. It is provided. This plunger is connected to the pump mechanism via a cam mechanism, rotates in synchronization with the rotation of the internal combustion engine, and also moves in a straight line, transferring the fuel filled in the cylinder to each cylinder through the hole in the cylinder side wall. Inject in sequence. The fuel injection timing is automatically adjusted by a hydraulic mechanism that controls the cam mechanism according to the discharge pressure of the pump mechanism.

This conventional fuel injection device has a structure in which the opening time of the fuel suction port of the cylinder of the pressure distribution mechanism is inversely proportional to the rotation speed of the plunger. There is a problem that the filling efficiency decreases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a distribution type fuel injection device that is configured so that the fuel filling efficiency into the cylinder of the pressure distribution mechanism does not decrease even in a high rotational speed region.

For this purpose, in the distribution type fuel injection device of the present invention, the transmission mechanism including the cam mechanism that connects the pump mechanism and the pressure distribution mechanism is moved from the fuel pressure chamber in the casing, that is, the pressure distribution mechanism, to the fuel outside the casing. The fuel passage that communicates the discharge port of the pump mechanism with the suction port of the pressurizing distribution mechanism is provided in the passage for surplus fuel returned to the source, and the fuel passage that communicates the discharge port of the pump mechanism with the suction port of the pressurizing distribution mechanism has a pressure adjustment mechanism that operates according to the pressure of the fuel in this fuel passage. It is communicated with the fuel pressure chamber through a valve.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial sectional view schematically showing the main parts of a fuel injection device according to an embodiment of the present invention. This fuel injection device has a pump mechanism M provided within a casing 10. Fuel supplied from the fuel source R passes through a fuel passage 12 formed in the wall of the casing 10 and reaches the suction port IN of the pump mechanism M. The pump mechanism M is a crankshaft (not shown) of an internal combustion engine.
The fuel is pumped by a drive shaft (not shown) connected to the engine.

The pressurizing distribution mechanism D, which sequentially injects fuel into a plurality of cylinders of an internal combustion engine via a valve V, has a cylinder 16 fitted and fixed in a through hole 14 of a casing 10, as shown in FIG. , and a cylindrical plunger 18 engaged with a circular cross-section shaft hole of the cylinder. The outer end of the shaft hole of the cylinder 16 is
It is closed by suitable means 20, for example screws. In the part near the outer end of the cylinder 16,
A hole 22 is formed that communicates the inside and outside of the cylinder 16, and the fuel pumped from the pump mechanism M flows into the cylinder 16 through the hole 22 through a fuel passage 24 formed in the wall of the casing 10.

The plunger 18 has a hole 26 extending along its central axis from its distal end facing the screw 20, and the hole 26 has an opening 28 in the side surface of the plunger 18. A plurality of grooves 30 (only one shown) are provided on the circumferential side of the tip of the plunger 18, spaced apart from each other in the circumferential direction and extending in the longitudinal direction of the plunger 18, respectively. On the other hand, the cylinder 16 has a plunger opening 2.
cylinder 16 at an axial position where it can communicate with cylinder 8;
Holes 32 having the same number as the grooves 30 and similarly spaced apart from each other in the circumferential direction so as to communicate the inside and outside of the
(only one shown) is formed. The casings 10 each communicate with the holes 32 of the cylinders.
Holes 34 (only one shown) formed in the walls of the cylinders communicate with the cylinders of the internal combustion engine through valves V, respectively.

The plunger 18 is connected to a drive shaft (not shown) that drives the pump mechanism M by a transmission mechanism 36 installed in the fuel pressure chamber C within the casing 10. The transmission mechanism 36 includes a cam mechanism (not shown) that periodically reciprocates the plunger 18 in its longitudinal direction, and moves the plunger 18 in synchronization with the rotation of the drive shaft, that is, with the rotation of the internal combustion engine. It rotates and makes the reciprocating motion. A portion of the fuel that has entered the cylinder 16 flows out into this fuel pressure chamber C through a hole 38 at the rear end of the plunger 18.
The fuel that has leaked into the fuel pressure chamber C is transferred to the casing 1.
The fuel is returned to the fuel source R via the hole 40 at 0.

A piston 44 is disposed inside a cylinder hole 42 that branches from the fuel passage 24 in the wall of the casing 10 and communicates with a hole 40 of the casing 10, and a spring 48 resists the pressure of the fuel in the fuel passage 24. The piston 44 is energized.
That is, one end surface of the piston 44 is connected to the fuel passage 24.
The opposite end face receives the fuel pressure in the fuel pressure chamber C and the repulsive force of the spring 48. A passage 46 branched from the cylinder hole 42 within the movable range of the piston 44 communicates with the fuel pressure chamber C, and therefore the piston 44
moves within the casing hole 42 according to the fuel pressure in the fuel passage 24 and the fuel pressure chamber C to open the passage 46.
It acts as a valve body of a pressure regulating valve that opens and closes to keep the difference in fuel pressure in the fuel passage 24 and fuel pressure chamber C at a predetermined value determined according to the characteristics of the spring 48. Note that reference numeral S represents a fuel supply cutoff valve controlled by an engine switch (not shown) of the internal combustion engine. The fuel supply cutoff valve S has an electromagnetic drive means that drives the valve body 50 under the control of the engine switch, and this electromagnetic drive means is energized to move the valve body 50 upward when the engine switch is in a conductive state. Fuel passage 24
to open.

In this fuel injection device, the plunger 18
rotates and reciprocates in synchronization with the rotation of the crankshaft. When the plunger 18 retreats, one of the plurality of grooves 30 (same number as the cylinders of the internal combustion engine) on the peripheral side surface of the tip of the plunger 18 communicates with the hole of the cylinder 16, while the hole defined by the cylinder 16 and the plunger 18 The volume of the high pressure chamber 52 increases, and fuel flows into the high pressure chamber 52 from the fuel passage 24. When the plunger 18 moves forward, the groove 30 is in an angular position where it does not communicate with the bore 22, while the volume of the high pressure chamber 52 decreases and the fuel in the high pressure chamber flows through the bore 32 of the cylinder and the bore 34 of the casing 10. It is injected into the cylinder through valve V. The timing of the linear reciprocating motion relative to the rotation angle of the plunger 18 is controlled by a hydraulic control mechanism 54 that acts on the transmission mechanism 36 according to the pressure of the fuel in the fuel pressure chamber C. The control sleeve 55 fitted into the plunger 18 is moved along the plunger 18 according to the rotational speed of the internal combustion engine by a control mechanism (not shown) provided in the casing 10, and the pressurized forward movement of the plunger 18, i.e. The effective stroke of the movement for pressurizing the fuel in the high pressure chamber 52 is controlled to control the amount of fuel injected into the cylinder each time the plunger 18 reciprocates.

In order to adjust the pressure within the fuel pressure chamber C, a second pressure regulating valve 58 is provided in a passage 56 that communicates the fuel pressure chamber C and the fuel passage 12. The second pressure regulating valve 58 opens the passage 56 when the pressure within the fuel pressure chamber C exceeds a predetermined value, thereby maintaining the pressure of the fuel within the fuel pressure chamber C below a substantially constant value.

As is clear from the above, in this fuel injection device according to the present invention, the fuel pressure in the fuel passage 24 from the pump mechanism M to the pressure distribution mechanism D is controlled by the pressure control valve including the piston 44 into the fuel pressure chamber. It is possible to adjust to a higher value than the pressure in C. Therefore, according to the present invention, when the rotational speed of the crankshaft is high, the groove 30 at the tip of the fuel inlet, that is, the plunger 18 in the pressure distribution mechanism D
Even when the time during which the cylinder 16 communicates with the fuel passage 24 is short, the efficiency with which fuel is filled into the cylinder 16 can be maintained at a required level.

FIG. 3 is a partial sectional view showing a fuel injection device according to another embodiment of the present invention. The embodiment shown in FIG. 3 differs from those shown in FIGS.
This embodiment differs only from the embodiment shown in the figure, and other parts have the same structure.

In the embodiment shown in FIGS. 1 and 2, a pressure regulating valve is provided in the fuel passage 24 separately from the fuel supply cutoff valve S, but in the embodiment shown in FIG. The structure is such that the valve S also functions as a pressure regulating valve. A guiding sleeve 66 is provided at the lower part of the head 64 in which the electromagnetic driving means of the valve S is housed, and the valve body 68 is guided by this sleeve 64 and can move up and down. The springs 70 and 72 engage with the lower surface of the head 64 and the upper surface of the valve body 68 on the inside and outside of the sleeve 66, respectively, and urge the valve body 68 downward. When the engine switch is off, that is, in a non-conducting state, the electromagnetic drive means installed in the head 64 is deenergized, and the valve body 68, which cuts off the fuel supply and adjusts the pressure, is moved by the springs 70, 7.
2 and closes the fuel suction hole 22 of the cylinder 16, similar to the embodiment shown in FIGS. 1 and 2.
At this time, due to the deenergization of the electromagnetic drive means, the fuel passage 2
This means that the pressure regulating valve No. 4 is closed. A second groove formed along the outer surface of the sleeve 66
The spring chamber 73 is communicated with the fuel pressure chamber C within the casing via a passage 75 formed in the wall of the casing 10.

The passage 74 formed in the valve body 68 is connected to the sleeve 6
6 and the upper part of the valve body 68 is communicated with the fuel passage 24, and the valve body 68 has an opening 78 in its side surface. When the engine switch is on, the electromagnetic driving means of the fuel supply cutoff valve S is energized, and the valve body 68 is moved by the spring 7.
It rises to the position shown in FIG. 3 against a force of 0.72. At this time, when the fuel pressure in the fuel passage 24 becomes higher than a predetermined value, the valve body 68 further rises.
The fuel passage 24 is communicated with the fuel pressure chamber C within the casing via the passage 74 of the valve body and the passage 46 of the casing 10.

Therefore, also in the embodiment shown in FIG. 3, the fuel pressure in the fuel passage 24 can be adjusted to a desired pressure higher than the fuel pressure in the fuel pressure chamber C in the casing, so that the rotational speed of the internal combustion engine can be increased. Even when the pressure is high, the fuel filling efficiency into the cylinder 16 of the pressurized distribution mechanism can be maintained at a required level. Also,
The embodiment shown in FIG. 3 has a simpler structure and requires less manufacturing cost than the embodiments shown in FIGS. 1 and 2.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a fuel passage in a fuel injection device according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a part of the embodiment of FIG. 1, and FIG. FIG. 7 is a sectional view showing a part of a fuel injection device according to another embodiment of the invention. Explanation of symbols of main parts, 10...Casing,
16...Cylinder, 18...Plunger, 24
... Fuel passage, 44 ... Piston, 48, 70,
72... Spring, D... Pressure distribution mechanism, M...
...Pump mechanism, S...Fuel supply cutoff valve.

Claims (1)

[Scope of Claims] 1. A casing, a pump mechanism that is provided in the casing and works in conjunction with a crankshaft of a multi-cylinder internal combustion engine to pump fuel supplied from a fuel source outside the casing, and the casing a pressurizing and distributing mechanism that is provided in the internal combustion engine and works in conjunction with the pump mechanism to pressurize the fuel fed under pressure from the pump mechanism and sequentially and periodically inject the fuel into a plurality of cylinders of the internal combustion engine; In the fuel injection device, a transmission mechanism that connects the pump mechanism and the pressure distribution mechanism is provided in a fuel pressure chamber in the casing, and the discharge port of the pump mechanism is connected to the suction of the pressure distribution mechanism. A fuel injection device characterized in that a fuel passage communicating with the port communicates with a fuel pressure chamber in the casing via a pressure regulating valve that operates according to the pressure of fuel in the fuel passage. 2. Claims characterized in that the fuel pressure chamber within the casing is communicated with the suction port of the pump mechanism via a second pressure regulating valve that operates according to the pressure of the fuel pressure chamber. The fuel injection device according to item 1. 3. An electromagnetic drive means is provided that is controlled by an engine switch of the internal combustion engine to drive the pressure regulating valve, and when the engine switch is in a non-conducting state, the electromagnetic drive means is deenergized and the fuel passage is Claim 1 or 2 is characterized in that the pressure regulating valve is closed.
The fuel injection device described in Section 1.