JPS6338361Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distributed fuel injection pump for internal combustion engines.

In conventional distribution type fuel injection pumps, the governor mechanism and timer mechanism are extremely complicated, which not only poses structural problems, but also results in poor control accuracy of injection amount and injection timing.

In view of these circumstances, the present invention aims to provide a distribution type fuel injection pump with a novel structure.

For this reason, the present invention includes an auxiliary plunger that reciprocates while rotating, and a main plunger that is connected to the tip of the auxiliary plunger in the rotational direction via a rod part and is urged in the axial direction by a spring in the abutment direction. is provided, and a distribution mechanism is provided that connects the main pressure chamber on the tip side of the main plunger to piping to the fuel injection nozzle of each cylinder sequentially for each compression stroke,
a fuel return passage that communicates the main pressure chamber with a fuel reservoir on the low pressure side at the top dead center position of the main plunger;
an electromagnetic metering valve that is interposed in the fuel suction passage to the main pressure chamber and is controlled to open from the start of the suction stroke until an amount of fuel corresponding to the required injection amount is sucked into the main pressure chamber; a fuel suction passage including a one-way valve for sucking fuel into an auxiliary pressure chamber between the auxiliary plunger and the main plunger; It includes a rotatable timer ring that has a fuel relief passage that releases fuel from the auxiliary pressure chamber when it matches the fuel relief groove on the plunger side, and an electromagnetic device that controls the rotational position of the timer ring based on the requested injection timing. To provide a distribution type fuel injection pump including an actuator.

The present invention will be explained below based on an embodiment shown in FIG.

Pump housing 1 has a head side (right side in the figure).
The sliding holes 2 and 3 are formed concentrically, and a main plunger 4 is inserted into the sliding hole 2 on the head side so that it can rotate and reciprocate. Further, a timer ring 5 is rotatably inserted into the sliding hole 3, and an auxiliary plunger 6 is inserted into the timer ring 5 so as to be rotatable and reciprocating. A main pressure chamber 7 is formed on the head side of the main plunger 4, and an auxiliary pressure chamber 8 is formed between the auxiliary plunger 6 and the main plunger 4.

A fuel reservoir 9 is formed on the bottom side of the timer ring 5 and the auxiliary plunger 6, and this fuel reservoir 9 is connected to a fuel inlet passage 12 connected to a fuel tank (not shown) by a vane type feed pump 11 driven by a drive shaft 10. Fuel is drawn in, pressurized, and guided. The fuel pressure in this fuel reservoir 9 is regulated by a regulating valve 13. Reference numeral 14 denotes an overflow orifice, which is connected to a fuel tank by a pipe (not shown).

The auxiliary plunger 6 is urged toward the fuel reservoir 9 side by a spring 15, and a cam disc 16 is provided on the portion of the auxiliary plunger 6 that exists on the fuel reservoir 9 side.
is fixed. The cam disc 16 has the same number of cam ridges as the number of cylinders, which are equally spaced.
A is formed, and the face cam 16a is pressed against a roller 18 held by a roller holder 17 fixedly installed in the fuel reservoir 9. and,
The drive shaft 10 and the cam disk 16 are coupled only in the rotational direction. Therefore, as the drive shaft 10 rotates, the cam disc 16
rotates, and at this time a predetermined lift is repeated.
Therefore, the auxiliary plunger 6 reciprocates while rotating, and in the case of a four-cylinder engine, reciprocates four times per revolution.

The auxiliary plunger 6 and the main plunger 4 are connected only in the rotational direction via the rod portion 4a.
However, the main plunger 4 is biased by a spring 19 housed in the main pressure chamber 7 so that the rod portion 4 a is pressed against the auxiliary plunger 6 .

The fuel reservoir 9 and the main pressure chamber 7 are connected to a fuel intake passage 20
An electromagnetic metering valve 21 is interposed in this fuel intake passage 20 . The electromagnetic metering valve 21 opens for an appropriate time from the top dead center of the main plunger 4 in response to a signal from the control unit 23 to regulate the amount of fuel sucked into the main pressure chamber 7.

The main plunger 4 is formed with a communication hole 24 that opens toward the main pressure chamber 7 side, and a distribution groove 25 is formed in the outer peripheral surface of the main plunger 4 in series with the communication hole 24 . Further, fuel discharge passages 26 of the same number as the number of cylinders are radially and equidistantly formed in the sliding hole 2 forming portion of the pump housing 1, and each fuel discharge passage 26 is provided with a delivery valve 27. 27 is connected by piping to a fuel injection nozzle (not shown) of each cylinder. Here, the distribution groove 25 and the fuel discharge passage 2
Reference numeral 6 constitutes a distribution mechanism that sequentially connects the main pressure chamber 7 to piping to the fuel injection nozzle of each cylinder for each compression stroke. In addition, a fuel return passage 28 is formed in the sliding hole 2 forming portion, and the fuel return passage 28 matches the distribution groove 25 at the top dead center position of the main plunger 4.
is in communication with the fuel reservoir 9.

The fuel reservoir 9 and the auxiliary pressure chamber 8 are connected to the fuel intake passage 2
9, and a one-way valve 30 is interposed in this fuel intake passage 29.

The auxiliary plunger 6 is formed with a communication hole 31 that opens to the auxiliary pressure chamber 8 side, and a fuel relief groove 32 for a timer is formed on the outer circumferential surface of the communication hole 31 . Furthermore, the timer ring 5 has fuel relief passages 33 of the same number as the number of cylinders formed at equal intervals on the inner circumferential surface side, and each fuel relief passage 33 communicates with the fuel reservoir 9.

The timer ring 5 is engaged with a cylinder-shaped electromagnetic actuator 35 via a pin 34, and the timer ring 5 is rotated by the operation of the electromagnetic actuator 35, and its rotational position is controlled. The electromagnetic actuator 35 is adapted to operate in response to a signal from the control unit 23.

The control unit 23 includes a rotation speed sensor,
Receives various information from load sensors, crank angle sensors, nozzle lift sensors, water temperature sensors, etc., issues signals corresponding to the required injection amount and injection timing based on the information, and operates the electromagnetic metering valve 21 and the electromagnetic actuator 35. control. Incidentally, the crank angle sensor 36 is provided opposite to a gear 37 formed integrally with the drive shaft 10.

Next, the operation will be explained with reference to the time chart shown in FIG.

At the top dead center (TDC) of the cam lift of the cam disc 16, the crank angle sensor 36
A TDC signal is generated, and from this moment on, the electromagnetic metering valve 21 is opened via the control unit 23.

At this time, the auxiliary plunger 6 and the main plunger 4 move to the left in the figure, and fuel is sucked into the main pressure chamber 7 whose volume is expanded accordingly from the fuel intake passage 20 via the electromagnetic metering valve 21. . The electromagnetic metering valve 21 continues to open until the amount of fuel required to provide the required injection amount is inhaled, and then closes.

When the electromagnetic metering valve 21 closes, the main pressure chamber 7 is sealed, so the main plunger 4 remains stationary and only the auxiliary plunger 6 moves to the left in the figure. Then, the volume of the auxiliary pressure chamber 8 is expanded, so that fuel is sucked into the auxiliary pressure chamber 8 through the fuel intake passage 29 provided with the one-way valve 30. This continues until the bottom dead center (BDC) of the cam lift.

When the compression stroke begins, the auxiliary plunger 6 moves to the right in the figure, but as long as the fuel relief groove 32 and the fuel relief passage 33 of the timer ring 5 match, the fuel in the auxiliary pressure chamber 8 will flow through them. The main plunger 4 is stationary because it is returned to the fuel reservoir 9.

The fuel relief groove 32 is opened by the rotation of the auxiliary plunger 6.
When the fuel release passage 33 of the timer ring 5 no longer matches the auxiliary pressure chamber 8, the main plunger 4 moves to the right in the figure. At this time, the distribution groove 25 and the fuel discharge passage 26 are aligned with each other due to the rotation of the main plunger 4, and the fuel in the main pressure chamber 7 compressed by the main plunger 4 flows through the communication hole 24, the distribution groove 25, and the fuel discharge passage 26. street,
The fuel is force-fed through the delivery valve 27 to a fuel injection nozzle (not shown), and is injected from the nozzle. Here, the amount of fuel sucked into the main pressure chamber 7 becomes the injection amount.

Then, when the main plunger 4 reaches top dead center,
The distribution groove 25 of the main plunger 4 is the fuel return passage 28
matches, and the injection ends. At this time, a suction-back action is performed.

Regarding the control of the injection timing, the control unit 23 operates the electromagnetic actuator 35 to adjust the rotational position of the timer ring 5.
The timing at which the fuel relief groove 32 of the auxiliary plunger 6 and the fuel relief passage 33 of the timer ring 5 no longer match can be adjusted.

As explained above, according to the present invention, it is possible to provide a distribution type fuel injection pump with a simple structure. Furthermore, since the injection amount is determined by electrically controlling the amount of fuel sucked into the main pressure chamber using a solenoid valve or the like, control accuracy is also improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a distribution type fuel injection pump showing an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of the same pump. 4... Main plunger, 4a... Rod part, 5...
...Timer ring, 6...Auxiliary plunger, 7...
...Main pressure chamber, 8...Auxiliary pressure chamber, 9...Fuel reservoir, 10...Drive shaft, 11...Feed pump, 16...Cam disc, 17...Roller holder, 20...Fuel suction passage, 21... ...Solenoid metering valve, 23...Control unit, 25
...Distribution groove, 26...Fuel discharge passage, 27...Delivery valve, 28...Fuel return passage, 29...
Fuel intake passage, 30... one-way valve, 32... fuel relief groove, 33... fuel relief passage, 35... electromagnetic actuator.

Claims (1)

[Scope of utility model registration request] In a distribution type fuel injection pump for an internal combustion engine that pressurizes and distributes injected fuel to each cylinder by a rotating and reciprocating plunger, the plunger includes an auxiliary plunger that rotates and reciprocates, and a tip side of the auxiliary plunger. A main plunger is connected to the main plunger in the rotational direction via a rod part and is urged in the contact direction by a spring in the axial direction. a fuel return passage that communicates the main pressure chamber with a fuel reservoir on the low pressure side at the top dead center position of the main plunger; an electromagnetic metering valve that is interposed in the suction passage and is controlled to open from the start of the suction stroke until an amount of fuel corresponding to the required injection amount is sucked into the main pressure chamber; a fuel suction passage equipped with a one-way valve for sucking fuel into an auxiliary pressure chamber between the auxiliary plunger and the auxiliary plunger; a timer ring that is rotatable and has a fuel release passage that releases fuel from the auxiliary pressure chamber when the fuel is met, and an electromagnetic actuator that controls the rotational position of the timer ring based on the requested injection timing. type fuel injection pump.