JPS6185570A - Unit injector of internal-combustion engine - Google Patents

Abstract

PURPOSE:To reliably obtain the starting augmentation of fuel and stop fuel injection when a failure occurs by arranging a plunger so that it can be rotated and adjusted in a plunger barrel selectively in three positions: normal-operation position, start position, and emergency stop position. CONSTITUTION:When a plunger 18 is in a start position, a fuel intake passage 13 is communicated to a plunger pressurized chamber via a group 29 and the first vertical groove 27. In addition, when the plunger 18 is in an emergency stop position, the communication from the fuel intake passage 13 and a fuel overflow passage 16 to the plunger pressurized chamber is cut off respectively by the plunger. Accordingly, the starting augmentation of fuel can be reliably obtained during a start. Furthermore, when a control device or a solenoid valve fails, fuel injection can be immediately stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a unit injector in which a fuel injection nozzle and a plunger for pumping fuel are integrally mounted on a cylinder head.

(Prior art and its problems) Conventionally, as such a unit injector,
No. 50726 is publicly known. This conventional type is configured so that the injection start and injection path can be controlled by a single solenoid valve, and when the voltage is low at startup (the power supply is low voltage due to driving the starter motor). ), the solenoid valve must be operated in order to increase the starting amount of fuel, so the operation of the solenoid valve becomes uncertain due to insufficient voltage, making it impossible to reliably obtain an increased amount of starting fuel. There is a problem with not being able to stop fuel injection immediately in the event of a failure.

(Objective of the Invention) The present invention has been made in view of the above circumstances. 1. Although the injection timing and injection amount can be controlled by controlling the closing time of the solenoid valve during normal operation, it is possible to control the injection timing and injection amount at the time of startup. It is possible to reliably increase the starting amount of fuel regardless of the solenoid valve.

It is an object of the present invention to provide a unit injector for an internal combustion engine that can immediately stop fuel injection by cutting off a fuel suction passage when a control device or a solenoid valve fails.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, a fuel pressure-feeding plunger fitted in the plunger barrel so as to be able to reciprocate in the axial direction is normally operated inside the plunger barrel. The plunger is arranged so that it can be selectively rotated to three positions: start position, emergency position, and stop position, and when the plunger is rotated to the normal operating position, the fuel intake passage and fuel overflow passage are connected to the plunger The plunger is provided with two longitudinal grooves that communicate with the pressurizing chambers, and a groove that communicates one of the longitudinal grooves with the fuel suction passage when the plunger is at the upper limit position and rotates to the starting position. The fuel suction passage and the fuel overflow passage communicate with the plunger pressurizing chamber through the longitudinal grooves when the plunger is in the normal operating position, and the fuel suction passage is provided in the plunger when the plunger is in the starting position. A passage is communicated with the plunger pressurizing chamber via the groove and the one longitudinal groove, and communication between the fuel overflow passage and the plunger pressurizing chamber is cut off by the plunger, and the plunger is further brought into an emergency stop position. At some point, communication between the fuel suction passage and the fuel swirl passage and the plunger pressurizing chamber is cut off by the plunger.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. FIG. 1 shows a vertical view of the unit injector of the present invention, and in the figure, 1 is the unit injector body, and the plunger barrel 2 is integrally provided. The plunger barrel 2
The fuel injection nozzle 3 is located at the lower end of the distance piece 4.
, 5 by a retaining nut 6. The nozzle 3 has a nozzle needle 8 fitted in a nozzle body 7 so as to be able to move up and down to open and close an injection hole (not shown) in the nozzle body 7. It is biased in the closing direction, that is, in the downward direction. A passage 10 provided in the distance piece 4°5 is connected between the inside of the plunger pressurizing chamber 2a of the plunger barrel 2 and the oil reservoir chamber (illustration +1J8) which is a pressurized space near the injection hole of the nozzle body 7. .11 and a passage provided in the nozzle body 7 (not shown).

A fuel inlet 12 provided on one side of the unit injector body 1 communicates with the interior of the plunger fitting chamber 14 of the plunger barrel 2 via a fuel suction passage 13 provided within the unit injector body 1. Further, a fuel outlet 15 provided on the other side of the unit injector body 1
communicates with the interior of the plunger fitting chamber 14 via a fuel overflow passage 16 provided within the Uniso injector body 1.

Incidentally, the opening end surfaces of the fuel overflow passage 16 and the fuel suction passage 13 with respect to the inside of the plunger fitting chamber 14 are at an angle of 180° from each other in the circumferential direction.
They are placed offset and facing each other.

A solenoid valve 17 is interposed in the middle of the fuel overflow path 16,
By controlling the closing time of the electromagnetic valve 17, the fuel injection timing and fuel injection amount can be controlled.

A fuel pressure-feeding plunger 18 is fitted in the plunger fitting chamber 14 so as to be rotatable and reciprocatable in the axial direction (vertical direction). As shown in FIG. 2, the plunger 18 can be selectively rotated into three positions: a normal operating position, a starting position, and an emergency stop position. That is, the plunger 18 is prevented from rotating with respect to a control sleeve 19 rotatably provided on the upper side of the unit injector body 1, and is slidably engaged in the axial direction. Pinion 2 fixed to the control sleeve 19
A rotation adjustment control rack 21 is engaged with the plunger 0, and by moving the control rack 21 in the direction of the arrow in FIG. 1, the rotation of the plunger 18 can be adjusted.

The control rack 21 is driven manually or by an appropriate driving means (not shown) such as a hydraulic piston and a stepping motor.

The plunger 18 is urged upward by a plunger spring 22, and the spring 22 connects a spring receiving member 23, which is a tappet fixed to the upper end of the plunger 18, and an inner part of a cylindrical part 24 protruding from the upper part of the unit injector body 1. It is interposed between the spring receiving step part 25 at the bottom. The spring receiving member 2
3 is fitted into a cylindrical cover 26 with a bottom.
Reference numeral 6 denotes a diameter fit that is slidably fitted to the inner circumferential surface of the cylindrical portion 24 .

A cam surface of a rotary cam (not shown) is in sliding contact with the upper end surface of the cover 26, and the cam is connected to the output shaft of an internal combustion engine 1'5g (not shown) and rotates in conjunction with the internal combustion engine. , the plunger 18 reciprocates as the cam rotates.

The plunger pressurizing chamber 2a is defined between the lower end surface of the plunger 18 of the plunger fitting chamber 14 and the upper end surface of the distance piece 4.

A first vertical groove 27 is provided on the negative side of the outer peripheral surface of the plunger 18, and a second vertical groove 28 is provided on the other side.

These first and second longitudinal grooves 27 and 28 are opposed to each other along the axial direction of the plunger 18 and offset by 180'' in the circumferential direction.

The lower ends of the first and second longitudinal grooves 27 and 28 are open at the lower end surface of the plunger 18, and the upper ends are located approximately in the middle of the plunger 18 in the axial direction. Furthermore, the first
The upper end position of the vertical groove 27 is approximately at the same level as the suction passage 13 at the upper limit position of the plunger 18, and the upper end position of the second vertical groove 28
It is set a predetermined dimension lower than the upper end position of 9.

Further, the upper end position of the second vertical groove 28 is set so as to maintain communication between the overflow passage 16 and the second vertical groove 28 throughout the entire lift of the plunger 18. When the plunger 18 is rotated to the normal operating position, the fuel suction passage 13 and the first vertical groove 27, and the fuel overflow passage 16 and the second vertical groove 28 are connected, respectively, as shown in FIG. It's becoming easier to communicate.

A groove 29 having a predetermined size and having one end communicating with the upper end of the first vertical groove 27 is provided on the outer circumferential surface of the substantially intermediate portion of the plunger 18 in the axial direction. When the plunger 18 in the upper limit position is rotated to the starting position, the groove 29 communicates with the fuel intake passage 13 as shown in FIG. 27 communicate with each other via the groove 29.

The driving means for the electromagnetic valve 17 and the control rack 21 are electrically connected to an electronic control device (not shown). Various data signals required for fuel injection control, such as engine speed, load, cooling water temperature, and exhaust gas temperature, are input to the electronic control device, and based on these signals, it is possible to determine the most suitable for the operating state of the engine. A signal is output to control the electromagnetic valve 17 to achieve appropriate injection timing and injection amount. The fuel port 12 is connected to a discharge port of a feed pump (both not shown) via a pipe, and the fuel outlet 15 is connected to a fuel tank (both not shown) via a pipe. It is. Furthermore, the first
In the figure, reference numerals 30 and 31 indicate return passages for introducing leaked fuel from the injection nozzle 3 into the fuel suction passage 13, which are provided in the distance piece 4 and the unit injector body 1, respectively.

(Operation) Next, the operation of the unit injector for the internal combustion engine of the present invention having the above-mentioned structure will be explained. First, during normal operation, the plunger 18 is rotationally adjusted to the normal operating position as shown in FIG. 2(A) by driving the control rack 2'' manually or by a driving means. In this state, when the plunger 18 is at the upper limit position, the fuel suction passage 13 and the plunger pressurizing chamber 2a, and the fuel overflow passage 16 and the plunger pressurizing chamber 2a are each 1% vertically! ! 27 and a second vertical groove 28.

In this state, the rotation of the cam causes the cover 26 to
When a periodic operating force is applied to the spring receiving member 23, which is a tappet, the plunger 18 reciprocates in the vertical direction within the plunger fitting chamber 14 in combination with the urging force of the plunger spring 22, and its upward stroke Fuel is drawn into the pressurizing chamber 2a from the fuel population 12 through the fuel suction passage 13 and the first longitudinal groove 27, and in the subsequent downward stroke, the fuel is sucked into the pressurizing chamber 2a.
is closed by the peripheral wall surface of the plunger 18 and the fuel vortex flow path 16 is closed by the solenoid valve 17, the sucked fuel is pressurized and becomes high pressure and flows into the oil sump chamber through the first passage 10.11. Sent. As a result, the pressure within the oil reservoir chamber increases, and when this pressure overcomes the biasing force of the nozzle spring 9 (reaching the valve opening pressure), the nozzle needle 8 rises to open the valve and fuel is injected from the injection hole. In this case, the solenoid valve 17
The injection timing can be controlled by controlling the timing of closing the valve, and the injection amount can be controlled by controlling the valve closing time. This valve closing time is controlled by an output signal from the electronic control device, and the internal combustion The optimum injection timing and injection amount are determined according to the operating condition of the engine.

Next, when starting the internal combustion engine, the control rack 21 is driven to move the plunger 18 to the starting position (Ii!14 clockwise from the normal operating position) as shown in FIG. 2(B).
Adjust the rotation to a position rotated 5 degrees). In this state, when the plunger 18 is at the upper limit position, the suction passage 13 sequentially passes through the groove 29 and the first vertical groove 27 to the pressurizing chamber 2.
a, the overflow passage 16 and the second vertical groove 28 are offset from each other in the circumferential direction, and the overflow passage 16 is closed by the peripheral wall surface of the plunger 18, so that the overflow passage 16 and pressurized chamber 2a
Communication with has been cut off.

In such a state, during the upward stroke of the plunger 18, fuel is sucked from the fuel population 12 into the pressurizing chamber 2a through the fuel suction passage 13, the groove 29, and the first vertical groove 27 in order, and the subsequent downward movement When the suction passage 13 is closed by the peripheral wall surface of the plunger 18 during the stroke, the inhaled fuel is immediately pressurized, and when the pressure in the oil reservoir reaches the UFJ valve pressure as described above, fuel is discharged from the injection hole. Injected. In this case, communication between the overflow passage 16 and the pressurizing chamber 2a is always cut off, and the fuel sucked into the pressurizing chamber 2a is transferred to the plunger 18.
The entire amount of fuel is injected from the injection hole without any overflow during the downward stroke of the engine, and therefore, regardless of the solenoid valve 17, an increase in the amount of fuel at the time of starting can be reliably obtained.

Furthermore, if the electronic control device or solenoid valve 17 breaks down and fuel injection control is no longer possible, the control rack 21 is driven to move the plunger 18 as shown in FIG. 2(C).
The rotation is adjusted to the emergency stop position (a position rotated approximately 45 degrees counterclockwise from the normal operating position) as shown in FIG. In this state, the first and second longitudinal grooves 27 and 28 and the groove 2
9 are offset from each other in the circumferential direction with respect to the suction passage 13 and the overflow passage 16, and the suction passage 13 and the overflow passage 16 are closed by the peripheral wall surface of the plunger 18, so that the suction passage 13 and overflow path 16 are both in a state of being blocked from the pressurizing chamber 2a.

In such a state, even if the plunger 18 rises, fuel is not sucked into the pressurizing chamber 2a, so fuel injection is not performed, and the internal combustion engine is therefore brought to an emergency stop.

(Effects of the Invention) As described above, the unit injector for an internal combustion engine of the present invention has a fuel pressure-feeding plunger fitted in the plunger barrel so as to be able to reciprocate in the axial direction. The plunger is arranged so as to be able to be selectively adjusted to rotate at three emergency stop positions, and when the plunger is rotated to the normal operating position, the fuel suction passage and the fuel swirl flow passage are respectively communicated with the plunger pressurizing chamber. The plunger is provided with two longitudinal grooves, and a groove is provided in the plunger that communicates one of the longitudinal grooves with the fuel suction passage when the plunger is at the upper limit position and rotates to the starting position. When in the normal operating position, the fuel suction passage and the fuel overflow passage communicate with the plunger pressurizing chamber via both longitudinal grooves, and when in the starting position, the fuel suction passage communicates with the groove and one of the two longitudinal grooves. communicates with the plunger pressurizing chamber through a longitudinal groove, and communication between the fuel overflow path and the plunger pressurizing chamber is cut off by the plunger, and when the plunger is in the emergency stop position, the fuel suction path and Since communication between the fuel overflow path and the plunger pressurizing chamber is configured to be cut off by the plunger, the injection timing and injection amount can be controlled by controlling the closing time of the solenoid valve during normal operation. Even though it is controllable, it is possible to reliably obtain an increased amount of fuel at startup regardless of the solenoid valve, and in the event that the control device or solenoid valve breaks down.

Since fuel injection can be immediately stopped by cutting off the fuel suction passage, and existing components can be used, costs can be reduced and the fuel injection system can be provided at low cost.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a unit injector, and FIG. 2 is an explanatory diagram of its operation. 2... Plunger barrel, 2a... Plunger pressurizing chamber, 3... Fuel injection nozzle, 13... Fuel suction path,
14...Plunger fitting chamber, 16...Fuel vortex flow path, 1
7... Solenoid valve, 18... Fuel pressure feeding plunger, 2
7..First vertical groove, 28..Second vertical groove, 29..
groove.

Claims (1)

[Claims] 1. The fuel injection nozzle and the plunger for pumping fuel, which is fitted in the plunger barrel so as to be able to reciprocate in the axial direction, are integrally attached to the cylinder head, and the solenoid valve installed in the fuel overflow path In a unit injector for an internal combustion engine in which injection timing and injection amount can be controlled by controlling valve closing time, the plunger can be selected from three positions within a plunger barrel: a normal operating position, a starting position, and an emergency stop position. When the plunger is rotated to the normal operating position, the two vertical grooves that communicate the fuel suction passage and the fuel overflow passage with the plunger pressurizing chamber are connected to the plunger pressurizing chamber. The plunger is provided with a groove that communicates the one longitudinal groove with the fuel suction passage when the plunger is at the upper limit position and rotated to the starting position, and when the plunger is in the normal operating position. The fuel suction passage and the fuel overflow passage communicate with the plunger pressurizing chamber through both the vertical grooves, and when the plunger is in the starting position, the fuel suction passage communicates with the plunger pressurizing chamber through the groove and the one vertical groove. The plunger is in communication with the fuel overflow passage and the plunger pressurization chamber, and communication between the fuel overflow passage and the plunger pressurization chamber is cut off by the plunger, and when the plunger is in the emergency stop position, the fuel suction passage and the fuel overflow passage are connected to the plunger pressurization chamber. A unit injector for an internal combustion engine, characterized in that communication with the plunger pressurizing chamber is cut off at each of the plungers.