JPS6014908B2 - Fuel injection device for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for internal combustion engines, and in particular to a fuel injection device that does not require return piping to a fuel tank, and is suitable for use in automobile diesel engines, gasoline engines, etc. It is something.

Conventionally, in a fuel injection system that combines a Bosch-type fuel injection pump and an internally-opening automatic valve for fuel injection, in order to return leaked fuel from the internally-opening automatic valve to the fuel tank, fuel is removed from the internally-opening automatic valve. A disadvantage is that a long return piping to the tank is required, making the piping work extremely complicated. In view of the above points, the present invention can eliminate the need for piping to return leaked fuel from the internally-opening automatic valve to the fuel tank, and at the same time, can maintain the barrier pressure of the internally-opening automatic valve almost constant. The purpose is to provide a fuel injection device.

Next, the apparatus of the present invention will be described in detail based on the illustrated embodiment.

In the drawings, a fuel injection pump 1 is comprised of a potsh type plunger pump having pump elements corresponding to the number of cylinders of an internal combustion engine, and the illustrated portion corresponds to one of the cylinders.

In this Botsch type pump, as is well known, fuel flows into a fuel chamber 2 by an oil feed pump (not shown) and further into a fuel boat 4 provided in a cylinder 3. This fuel is transferred to the plunger 5 which is iron-coupled to the cylinder 3.
It flows into the pump chamber 6 during the downward movement of the plunger 5, and is compressed and pumped during the upward movement of the plunger 5. The plunger 5 is driven by a camshaft (not shown), and has a diagonal notch 5a at its upper end and a straight notch 5b below it.When the diagonal notch 5a passes the fuel boat 4 when the plunger rises, the fuel starts to be compressed, and the straight notch 5b becomes the boat 4.
When polymerization occurs, the pumping of fuel is terminated.
Here, the fuel injection amount is changed by rotating the plunger 5 from the outside of a control rack (not shown) and changing the effective pumping stroke amount. The fuel pumped during the upward stroke of the plunger 5 passes through the passage 6' of the spring holder 7, the spring chamber 8, and the discharge passage 10 of the valve seat body 9, and then reaches the discharge valve 11.
When the fuel pressure reaches the opening pressure of the discharge valve 11 or higher, the discharge valve 11 is pushed open and passed through the spring chamber 13 of the cap body 12 and from the connection boat 14 through the high pressure piping 15 to the internal opening type automatic valve body. 16 connection boats 17. From this connecting boat 17, fuel is further passed through passage 1.
8, 19, and 20 to reach the annular oil groove 22 of the relay body 21, and from this oil groove 22, it passes through a plurality of passages 23, an annular groove 25 of an internally-opening automatic valve 24, a passage 26, and then a pressure chamber 27. It is designed to reach. 28 is a valve seat part, and the needle valve 31
Good oil tightness is maintained between the

Pressure feeding of fuel from the injection pump increases the pressure in the pressure chamber 27 of the internally opening type automatic valve 24, and a spring chamber forms a leakage fuel discharge part that receives leaked fuel from the needle valve sliding part 35 of the internally opening type automatic valve 24. When the force of the spring 30 housed in the spring 29 is overcome by the force of the pressure in the pressure chamber 27 that lifts up the needle valve 31, the needle valve 31 is lifted upward in the figure and the fuel is transferred to the false opening 3.
From 2 onwards, it is injected into the engine's cylinders. A throttle 33 and a pressure setting valve 34 are provided on the valve seat body 9 in parallel with the discharge circuit 10 and the discharge valve 11. This allows fuel to flow to the pump chamber 6 side, and if the reflected pressure wave or residual pressure after injection is high, the fuel will flow to the pump chamber 6 side.
3, a pressure setting valve 34 is engaged, the spring chamber 8 passes through a passage 6' to the pump chamber 6, and is further discharged into the fuel chamber 2 via the fuel boat 4. On the other hand, a part of the fuel injected from the inward-opening automatic valve 24 leaks into the spring chamber 29 through the sliding part 35 of the needle valve 31 and fills the spring chamber 29, and then passes through the passage 36 into the annular oil groove 37. It is designed to be guided by This annular oil groove 37 is formed in a two-way rotary joint 47 that has coupling passages 47b and 47b' in the left and right directions shown in the figure, and this rotary joint 47 has a nut 5
7 is tightened and fixed to the internal opening type automatic valve main body 16 in an oil-tight manner, and at this time, the annular oil groove 37 and the passage 36 are passed through each other in an oil-tight manner. Further, the annular oil groove 37 and the passage part 47b on one side (on the left side in the figure) are connected to each other by the oil hole 47a, and the annular oil groove 37 and the passage part 47b' on the other side (on the right side in the figure) are connected to the oil hole 47a.
A' is more suitable for lotus. Reference numeral 38 designates a pressure actuator, which includes a metal diaphragm 39 that serves as a pressure responsive member that is displaced against spring force, a spring 40 that acts on this diaphragm 39, a spring receiver 41, a counter-receiving housing 44, and a screw housing 44. It consists of a coupled outer cylinder 45, an adjusting screw 42, and a fixing screw 43.

The fuel passage 46 of this pressure actuator 38 is oil-tightly screwed to one passage portion 47b of the two-way rotary joint 47 via a gasket 48. Note that the spring chamber 40' that houses the spring 40 is open to the atmosphere. A one-way valve 50 is oil-tightly screwed to the other passage 47b' of the two-way rotary joint 47 via a gasket 49, and a throttle 51 is press-fitted into its inlet. The passage portion 47M is connected through the throttle 51.

Further, the one-way valve 50 includes a spherical movable valve portion 53, a spring 54,
A spring support 55 and a valve seat body 56 are built in, and the valve seat body 56 is press-fitted and fixed into the fuel passage hole 52. Further, the spring support 55 is screwed to the valve seat body 56 so that the spring force of the spring 54 can be adjusted. An outlet side connection boat 157 of the one-way valve 50 is connected to the high pressure pipe 15. In addition,
The inward-opening automatic valve 24 is vertically fixed to the automatic valve main body 16 by a holder 58, and the holder 58 has a threaded portion 58a that is tightened and fixed to the engine. Next, the operation of the above configuration will be explained.

The plunger 5 of the fuel injection pump 1 reciprocates in the vertical direction with the rotation of a camshaft (not shown) driven by the engine, and the upward movement of the plunger 5 causes the pump chamber 6 to
When the fuel inside is pumped, the fuel opens the discharge valve 11 as described above, passes through the high pressure pipe 15, reaches the internal opening type automatic valve body 16, and flows through each of the passages 17, 18, 19, and 20. The liquid then flows into the pressure chamber 27 through the relay body 21 and the passages 22, 23, 25, 26 of the internally-opening automatic valve 24. The fuel that has entered this pressure chamber 27 is then transferred to the needle valve 31.
is pushed upward in the figure and is injected into the engine from the dawn opening 32. At this time, as the needle valve 31 moves upward in the diagram, the leaked fuel filling the spring chamber 29 (the needle valve 31
Since the fuel that leaked into the spring chamber 29 from the sliding portion 35 of 1 is incompressible, it is immediately pumped to the passage 36 side, and flows from the oil groove 37 through the oil hole 47a and the oil hole 47a' to the rotary joint 4.
7 in parallel to the left and right passages 47b and 47b'. However, the movable valve portion 53 of the one-way valve 50 does not open because the pressure inside the high-pressure pipe 15 is high at this time. On the other hand,
In the pressure actuator 38, leaked fuel flows from the passage portion 47b through the fuel passage 46, and as a result, the metal diaphragm 39 is displaced to the left in the figure against the spring force of the spring 40, and the inside of the spring chamber 29 is displaced. Since the pressure of the leaked fuel is prevented from increasing, the valve pressure of the needle valve 31 can be kept almost constant. Then, when the pressure feeding of fuel from the injection pump is completed, the needle valve 31
immediately seats on the seating portion 28, and fuel injection ends.

The pressure wave generated at this time follows the aforementioned fuel passage in the opposite direction, passes through the connection boat 14 of the injection pump 1, and reaches the spring chamber 13. When the reflected pressure wave or residual pressure after injection is high, the fuel passes through the throttle 33 and opens the pressure setting valve 34, and the fuel is kept in the spring chamber until the pressure set by this valve 34 drops to, for example, 10k9/ground. Returned to 8. Since the fuel led to the spring chamber 8' passes through the passage 6' from the pump chamber 6 to the fuel boat 4 and is discharged to the fuel chamber 2, the pressure in the high pressure pipe 15 after fuel injection is set to the pressure in any case. A constant pressure determined by valve 34 is maintained. Further, as described above, when the needle valve 31 descends, the volume of the spring chamber 29 is expanded, so the diaphragm 39 of the pressure actuator 38 is pushed toward the right side in the figure by the spring 4, and the fuel in the pressure actuator 38 is Most of the fuel is returned to the spring chamber 29 and the pressure inside the spring chamber 29 drops, but if the pressure inside the spring chamber 29 is higher than the pressure inside the high pressure pipe 15, the fuel is returned to the oil groove 37, the oil hole 47a', The one-way valve 50 is opened through the passage portion 47b' through the throttle 51, and reaches the high-pressure pipe 15.

The fuel that has reached the high pressure pipe 15 passes through the pressure setting valve 34 in the injection pump 1 and is returned to the fuel chamber 2, and the pressure in the high pressure pipe 15 becomes a constant value determined by the pressure setting valve 34. In addition,
At this time, the throttle 51 prevents the movable valve portion 53 of the one-way valve 50 from opening too much and the pressure within the spring chamber 29 from fluctuating.
Note that, although the above-described embodiments illustrate preferred embodiments of the present invention, the present invention is not limited thereto and can be modified in various ways.

For example, the pressure actuator 38 is connected to the leakage fuel discharge section (spring chamber 29 section) of each internally opening automatic valve 24 corresponding to the number of cylinders of the engine.
Although the above description is based on the assumption that the pressure actuator 38 is installed in the
4 leakage fuel drain(s) and one pressure actuator 38
The fuel passage 46 may be connected to the fuel passage 46 by a pipe or the like.

Further, the throttle 51 does not need to be configured as a special part; for example, by narrowing a part of the passage from the two-way rotary joint 47 to the one-way valve 50, it can have that function. Of course there is. Further, in the pressure actuator 38, the diaphragm 3 is used as the pressure applying member.
9 has been shown, however, it is also possible to use a substitute for the diaphragm 39, a piston, etc. as the pressure responsive part.

It is also possible to connect the pressure actuator 38 and the one-way valve 50 directly to the internal opening type automatic valve body 16 without going through the two-way rotary joint 47. It may be built into the main body 16 and the outlet side connection boat 157 of the one-way valve 50 may be connected to the passage 18.

As described above, according to the device of the present invention, the fuel leaking from the needle valve sliding portion 35 of the internal opening type automatic valve 24 is returned to the high pressure piping 15 side via the one-way valve 50, which is different from the conventional method. This has the excellent effect of eliminating the need for a long pipe for returning leaked fuel, and furthermore, the action of the pressure actuator 38 prevents a pressure rise in the leaked fuel discharge section 29 of the internally opening type automatic valve 24. This has the excellent effect of keeping the opening pressure of the automatic valve 24 substantially constant. Furthermore, fuel injection pump 1
The residual pressure in the high pressure pipe 15 can be kept constant by the action of the pressure setting valve 34 provided in parallel with the discharge valve 11.
It has the excellent effect of preventing irregular injection into the engine.

[Brief explanation of the drawing]

The drawing is a sectional view showing an embodiment of the device of the present invention. 1...Fuel injection pump, 6...Pump chamber,
11...Discharge valve, 15...High pressure piping,
16...Inward opening type automatic valve body, 24...
Internal opening type automatic valve, 29...Spring chamber forming leakage fuel discharge section, 31...Needle valve, 34...Pressure setting valve, 35... Waiting section of needle valve 31, 38...
...Pressure actuator, 39...Metal diaphragm forming pressure response section, 50...One-way valve.

Claims (1)

[Claims] 1. In a fuel injection device for an internal combustion engine that supplies fuel discharged from a pump chamber of a fuel injection pump to an internally-opening automatic valve for fuel injection into the engine via a discharge valve and a high-pressure pipe, the fuel in the high-pressure pipe is A pressure setting valve capable of opening at a predetermined valve opening pressure and allowing flow to the pump chamber side is arranged in parallel with the discharge valve, and leakage from the needle valve sliding part of the internal opening type automatic valve is provided. A pressure actuator having a pressure-responsive member that is displaced against a spring force and a one-way valve are communicated in parallel with the fuel discharge portion, and the one-way valve is communicated with the fuel passage on the high-pressure piping side. 1. A fuel injection device for an internal combustion engine, characterized in that when a valve is opened, leaked fuel flows from the leaked fuel discharge portion to the fuel passage on the high pressure piping side.