JPS5827873A - Excess fuel discharge device for fuel injection pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection pump used in a diesel engine or the like, and particularly to a surplus fuel discharge device thereof.

FIG. 1 is a sectional view of a conventional fuel injection pump.

A rotor 1 is rotated by a drive shaft (not shown) rotating synchronously with the engine, and a pair of plungers 2 are accommodated in a hole passing through the left end of the rotor 1 laterally. There is.

A row 2 shoe 8 and a roller 9 are installed on the outside of the plunger 2. Roller shoes 8 and rollers 9 rotate together with rotor 1.

The cam ring 3 on the outer periphery of the row 29 is the outermost housing 1
It is installed in 0. Nine, rotor 1 is housing 1
The sleeve 42 is mounted in a sleeve holder 41 which is fixed at 0, and rotates inside the sleeve 42.

The inside of the tank is divided into a first pressurizing chamber 4 and a second pressurizing chamber 1i16, with a free piston 5 interposed between them.
Second pressurization I! The right end of 6 is sealed with a stopper 7.

Further, the second pressure release 6 communicates with a discharge passage 23 formed in the radial direction of the rotor 1, and the second radial passage 12 communicates with the sleeve 4.
It is provided corresponding to the second fixed passage 14 of No. 2.

On the other hand, the first radiation passage 11 communicating with the first pressurizing chamber 4 is provided corresponding to the first fixed passage 13 of the sleeve 42,
An overflow port 29 is provided in the lower part of the first pressurizing chamber 4, and is connected to the discharge passage 1632 through overflow passages 30, 311-.

A ninth first fixing passage 13 is formed in the sleeve 42. The opening of the second fixed passage 14 is connected to the jll solenoid valve 15. The valve body 17 of the second solenoid valve 16 is located opposite to the first solenoid valve 1.
5 and the second solenoid valve 16 were housed in a case 18;
and fixed magnetic pole 20. It is composed of a spring 21. A fuel supply port 43 is formed in the center of the sleeve holder 41, and the fuel introduced through this port fills the accommodation chamber of the valve body 17 of the solenoid valve 15, 16 and the rotor 1.

In addition, 22 is a terminal of the coil 19, 24 is an output path, and 25 is a connection port. Further, 27 is a female detector having an annular permanent magnet fixed to the end of the sleeve holder 41, and a pulser 27 attached to the rotor 1 is located inside the detector.
is inserted.

The pulsar 26 is a magnetic material with protrusions around its periphery, and is attached to the rotor 1.
When the pulser 26 rotates at the same time, the magnetic path is interrupted and a rotation signal is output from the detection terminal 28. This allows the rotational position and speed of the rotor I to be detected.

The operation of the fuel injection pump configured in this way will be explained with reference to FIGS. 2 to 7. The left side of these figures corresponds to the If-It sectional view of FIG. 1, and shows the state of the fuel pump. In addition, the diagram on the right side shows the relationship of the fuel flow path between the rotating rotor 1 and the sleeve 42 housing the rotor 1, and the position of the 7-lead piston 5.

Figure 2 shows the state at the start of the supply of injected fuel, and the plunger 2
a, 2b are moving outward. In FIG. 2(a), the reduced diameter portion of the inner surface of the cam ring 3 moves to the larger diameter portion, and as the first pressurizing chamber 4 is depressurized, the free piston 15 moves in the direction of the arrow and moves to the second pressurizing chamber 4. Pressure chamber 8t - Depressurize. Therefore, the injected fuel is sucked through the second radiation passage 12 and the M2 fixed passage M14.

Note that at this time, since the valve body 17b is open, pressurized fuel flows into the second pressurizing chamber 6. That is, in this case, fuel for injection is being sucked.

FIG. 3 shows a state in which the intake of the injected fuel has been completed and the supply of the injection timing adjustment fuel has started, and at this time the free piston has temporarily stopped and the valve body 171 has opened. Note that as the roller 9 rotates around the large inner diameter portion of the cam ring 3, the plunger 2 further depressurizes the first pressurizing chamber 4, and the first fixed passage 13. 1st radiation passage 1lt
-The injection timing adjustment fuel is taken in through the In addition, the valve body 17
It is also possible to open valves a and 17b at the same time to introduce fuel.

Figure 4 shows the state 1It- when the injection timing adjustment fuel supply has finished.
As shown, the plunger 2 and the free piston 5 are stopped, and the valve body 17 is both closed.

FIG. 5 shows a fuel injection start state M, in which the roller 9
is guided to the reduced inner diameter of the cam ring 3, so the plunger 2 begins to approach. Therefore, the free piston 5 moves in the right direction of the arrow to transfer the fuel in the second pressurizing chamber 6 to the discharge passage 2.
3. It is pumped via outlet port 1&24 to connection port 25 in FIG. Since the pipe attached to the connection port 25 communicates with the cylinder, a predetermined amount of fuel is supplied to the cylinder.

Figure 6 shows the start of exhaustion of excess fuel after fuel injection has ended!
1f: As shown, when the free piston 5 moves to the right side, the overflow port 29 is exposed, so the pressurized surplus fuel flows out through the overflow passage 30. Note that this fuel flows out to the low pressure section through the overflow passage 31 of the sleeve holder 41 shown in FIG.

That is, FIG. 1 shows the state at this time.

Figure 7 shows the state after the discharge of excess fuel9.
Free piston 5ti has stopped temporarily, but the second one will start soon.
It is about to move to the state shown in the figure and inhale the injected fuel.

What is understood from the above explanation is that a series of fuel intake and injection operations are performed while the rotor 1 rotates 90''. Note that the engine in this case is a 4-cylinder engine, so the rotor 1 is Fuel is injected into all cylinders during rotation. 9. The fuel sucked into the first pressurizing chamber 4 is a lot of fuel for adjusting the injection timing, and what is actually injected is #f2 is the fuel sucked into the pressurizing chamber 6.

The conventional fuel injection pump that operates in this manner discharges excess fuel after the fuel in the second pressurizing chamber 6 is injected.
At this time, since the opening area of the overflow port 29 does not increase rapidly, it takes time to force the free piston 5 to open.

Therefore, the next injection fuel to be introduced into the second pressurization 1i16 is excessively sucked in, making the movement of the free piston 5 unstable.

Furthermore, since the amount of introduced fuel changes depending on the overflow speed of surplus fuel, there is a drawback that the injection stability is affected by the number of revolutions of the rotor 1 and the amount of fuel determined at the injection timing.

An object of the present invention is to provide a surplus fuel discharge device for a fuel injection pump that can eliminate the drawbacks of the prior art and provide a stable fuel injection amount, and is characterized by:
The free piston is provided with a valve mechanism that opens as the free piston moves at the end of the fuel injection period and rapidly allows fuel for injection timing control to flow out.

FIG. 8 is a sectional view of a main part of a fuel injection pump according to an embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals. In this case, a movable valve body 51 is housed in the free piston 50, but the valve body 51 and the free piston 5
0 is airtightly fitted, so that the first pressure chamber 4 can be
The flange of the valve body 51 accommodated in the piston 50 is pressed by the spring 53 secured to the ring 54 and comes into close contact with the valve seat, so that the fuel does not move to the pressurizing chamber 6. It is blocking the distribution of.

However, when the free piston 50 moves to the right and reaches the stage where injection is completed and surplus fuel is discharged, the tip of the valve body 51 comes into contact with the tip of the stopper 7, and the collar of the valve body 51 separates from the valve seat and exits from the discharge port 52. Surplus fuel can cross over to the fuel flow path 30. In this case, the overflow port 29 and the aa passage 30 are larger-diameter holes than those in FIG. 1, so that excess fuel can rapidly flow out through these holes.

For example, the diameter of the seat portion that the flange of the valve body 51 is in contact with is 4mm.
Assuming that the gap between the valve body 51 and the seat portion is 0.1 cm, the cross-sectional area of the flow path through which fuel flows will be L26 cm. Furthermore, the fuel that has passed through this flow path has a larger cross-sectional area than the exhaust port 52 and the overflow port 29. Overflow l51I
It can be easily and quickly discharged from the escape route 30.

On the other hand, in the conventional free piston 5, the overflow port 29
If the diameter of the free piston 5 is 3sI, and if the free piston 5 moves α6■ to create an overflow part, the area will only be α998min8.

That is, in the case of this embodiment, surplus fuel can be quickly discharged by a slight movement of the free piston 50.

Note that since the end of the injection is performed at a fixed position of the free piston 50, it is easy to select the discharge port 52 to face the overflow port 29.

The surplus fuel discharge device of this embodiment is configured such that a valve body with a flange is set inside so that the valve body contacts the stopper when the free piston moves at its maximum, and even when the flange is slightly separated from the seat part. A relatively large amount of surplus fuel can be discharged in a short time. Therefore, the accuracy of the amount of fuel injected by the second pressurized plug is also improved. Furthermore, since the area where the free piston 50 receives pressure to the right before and after opening the discharge passage 23 is increased, the vibration phenomenon when excess fuel is discharged is suppressed, and the pressure inside the high-pressure pipe up to the injection valve is rapidly reduced. Since it is stabilized, it helps to prevent secondary injection and the like, and effects such as being able to improve the stability of fuel injection can be obtained.

The surplus fuel discharge device for a fuel injection pump according to the present invention has the advantage that surplus fuel can be discharged quickly and a stable fuel injection amount can be obtained.

[Brief explanation of the drawing]

Figure 1 is a sectional view of a conventional fuel injection pump, Figures 2 to 7
This figure is an explanatory view of the operation of the fuel injection pump shown in FIG. 1, and FIG. 8 is a sectional view of a main part of the fuel injection pump which is an embodiment of the present invention. 1... Rotor, 2... Plunger, 3... Cam ring, 4... First pressurizing chamber, 5.50... Free piston, 6... M2 application EE'M,? ...Stopper, 8
...Roller shoe, 9...Roller, 10...Housing, 11...First radiation passage, 12...Second radiation passage, 13...First fixed passage, 14...No. 2 fixed passage, 15 = 16... solenoid valve, 17... valve body, 23
...Discharge passage, 24-...Output passage, 25...Connection port, 26...Pulser, 27...Detector, 29-...
Overflow port, 30. 31... Overflow passage, 32... Discharge passage, 41... Sleeve holder, 42... Sleeve,
43...Fuel supply port, 51...Valve body, 52...Discharge port, 53...1th closed 2nd section (0,) (?ji 5th ding)

Claims (1)

[Claims] 1. A movable 7-Lee piston is installed in a high-pressure fuel chamber, which is partitioned by this free piston, and one chamber is supplied with fuel related to the injection amount, and the other chamber is In a fuel injection pump configured to supply fuel related to injection timing, the free piston moves and opens at the end of the fuel injection period, and the valve mechanism is configured to rapidly flow out fuel for injection timing control. What is provided on the free piston?
- Features a fuel IP + injection pump surplus fuel discharge device. 2. The valve mechanism causes a tip of a movable valve body to protrude into a chamber containing fuel related to the injection amount, and the valve body contacts a stopper at the end of the fuel injection period. 2. The surplus fuel discharge device for a fuel injection pump according to claim 1, which is a mechanism for separating fuel related to the injection timing from the valve seat and flowing out the fuel related to the injection timing from the overflow port.