JPS5941658A - Fuel injection unit - Google Patents

Abstract

PURPOSE:To eliminate the problem of malfunction in fuel injection due to low- grade fuel by installing a working oil supplying system, which operates a servo piston for an injector plunger, separately from a fuel feeding system. CONSTITUTION:An injector, in which a spool valve 26 is inserted into a spool valve chamber 23 within an injector body 13, lowers the spool valve 26 via a core 28 when a solenoid coil 8 is magnetized. A changeover valve 41, which is inserted into a changeover valve chamber 19 that is connected to the valve chamber 23 via an oil passage 17', is energized downward by a spring 42. Working oil, which is supplied from a working oil supply system via an oil passage 12 and a flow inlet 14 by opening the changeover valve 41, is introduced into a servo piston chamber 46 to lower a servo piston 50. With this contrivance, fuel, which has been supplied from a fuel feeding system to a fuel passage 54 via a fuel passage 12a and a flow inlet 14a, is pressurized to push up a needle 36, thereby being injected from a nozzle 55.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine suitable for the electro-hydraulic control system. The purpose is to prevent deterioration of operating characteristics due to high operating resistance due to high viscosity, increased wear, sticking, and temperature rise of the solenoid due to fuel heating. Reduces the load on the solenoid and reduces changes in solenoid characteristics due to temperature rise.
It is also part of the purpose of the present invention to increase the responsiveness of the servo piston.

Conventionally, an electro-hydraulic control fuel injection device has a structure in which an injector has a switching valve mechanism such as a pilot valve and a main valve, and a servo mechanism for operating a plunger, and a hydraulic oil supply system and a fuel oil supply system are provided separately. However, when low-heavy oil is used as fuel oil, it has a high viscosity and abnormal wear components (sludge, etc.) of the fuel injection device are mixed into the fuel oil, and the solenoid pilot valve and main valve Problems include operational failure of the servo mechanism (poor response, abnormal wear, sticking, etc.) and a decrease in the operating force and operating speed of the solenoid due to heating of the reservoir to avoid viscosity reduction.

The present invention aims to avoid the above-mentioned conventional problems by separately providing a hydraulic oil supply system and a fuel oil supply system in an electro-hydraulic control fuel injection device. .

The first line indicates when current is applied to the solenoid (fuel injection stroke).
In the figure, 1 is the engine %Sl is the electric control system,
1 is a hydraulic oil supply system, S and 1a are a fuel oil supply system, and S3 is an engine oil supply system. In the drowsiness control system 54, a rotational phase angle sensor 6 faces the flywheel 2 of the engine 1;
is the signal to the computer 5 IC via the signal wire 4
The output terminals 6 corresponding to each cylinder of the microcomputer 5 connect the signal path 7 to the jetter system 53.
Circle carp/l'8 (71/maid) K connected.

There is a supply pump 9 driven by the engine 1 in the hydraulic oil supply system S2, and the suction port of the pump 9 is connected to the filter 1.
The discharge port of the pump 9 passes through the oil passage 12 to the injector body 16.
It is connected to the hydraulic oil inlet 14 (hydraulic power source). A pressure regulating valve 15 is arranged in parallel with the pump 9, so that the oil pressure in the oil passage 12 is maintained at a constant level of 111LK. Also oil road 12
An accumulator 15 is connected to the oil passage 12, or a part of the oil passage 12 forms a collecting pipe that functions as an accumulator.

There is a fuel supply pump 9a driven by the engine 1 in the fuel oil supply system S, a, the suction port of the pump 9a is connected to the fuel tank 11aVc via the filter 108, and the discharge port of the pump 9a is connected to the oil path 12a. It is connected to the fuel inlet 14a of the injector body 16 through the injector body 16. pump 9
A pressure regulating valve 15a is arranged in parallel with the fuel oil passage 12a, thereby maintaining the fuel oil pressure in the fuel oil passage 12a at a constant value. Further, the fuel oil passage 12a Vc is connected to an accumulator 15a, or a part of the oil passage 12a forms a collecting pipe that functions as an accumulator.

Inside the injector body 16, the hydraulic oil inlet 1
4 has a first oil passage 17 (part of which is designated as 17') and a switching valve chamber 19 that both open downward, and a conical valve seat 20 and a sixth oil passage 21 that share the same window as the switching valve chamber 19. Both have upward openings. The first oil passage 17, 17' is connected to the upper end of the switching valve chamber 19 via the spool valve chamber 26, and the second oil passage 18 (partly designated as 18') at a position that does not communicate with the inlet 14 is, The servo piston chamber 46 is connected to the discharge oil passage 25 via the switching valve chamber 19 and the outlet 24. The second oil passage 18, 18' is opened and closed by the outer circumferential groove 48 of the switching valve 41.

A spool valve 26 is fitted into the spool valve chamber 26 so as to be able to rise and fall freely, and is biased upward by a solenoid spring 27 contracted between the bottom surface of the spool valve chamber 26 and the spool valve z6, and the solenoid coil Iv8Vc surrounding active core 2
8, the core 28 is held in the upper end part 1 against the elasticity of the solenoid valve spring 290, and the inner slanted part of the spool valve 26 [the provided outer circumferential groove 60 is the 11th passage 17 ' is in contact with the outlet 61 and is staring at it. Also spool valve 2
The lower spring chamber 62 of the spool valve chamber 26 is connected to the upper end of the spool valve chamber 26 through the /i11 passage 66 and is connected to the upper end of the spool valve chamber 26 and
4, the core chamber 65, and the core chamber 6 through the hole 66 in the core 28.
It communicates with the upper end of 5. The spring 29 is fitted onto the outer periphery of the upper end of an adjustment bolt 67 which also serves as a stopper, and the adjustment bolt 67 is screwed into the upper end of the body 16 and locked by a nut 68. A hole 69 in the center of the adjustment bolt 67 connects the upper end of the core chamber 65 to the discharge oil passage 25.

Inside the switching valve chamber 19 is a cup-shaped differential switching valve 41 that opens upward.
are slidably fitted, and the upper end surface of the switching valve chamber 19 and the switching valve 4
1 is biased downward by a spring 42 compressed between the two. The outer diameter of the lower half of the switching valve 41 decreases at the pressure shoulder section 46, and further decreases in diameter as it goes downward at the conical face section 44 near the F end, and a small-diameter throttle section 45 is formed below the conical face section 44. has been done. The face part 44 is a conical valve seat 2QVcM
This is the part where the valve seat 20 and the servo piston chamber 46 are seated, and the throttle part 45 is a part that fits into the hole 47Vc connecting the valve seat 20 and the servo piston chamber 46 with a slight gap left. The outer circumferential groove 48 of the switching valve 41 is in the second groove 18 in the state shown in FIG. 1 (second switching position to be described later).
18' is blocked.

A plunger 52 in a plunger chamber 51 is connected (abutted or fixed) to a servo piston 50 in a servo piston chamber 46. The lower end of the servo piston chamber 46 is connected to an outlet 56 (il- to a discharge oil passage). Connect to 25a.

The lower end of the plunger chamber 51 passes through the fuel oil passage 54 and is connected to the nozzle 5.
5, and also connected to the lower end of a supply valve chamber 57 parallel to the plunger chamber 51.

The upper end of the valve chamber 57 is connected to the fuel inlet 14a via the fourth channel 22, and a downwardly opening cup-shaped supply valve 59 having a conical face portion 58 at the upper end is installed in the chamber 57 (
f5. The face portion 58 is biased in both directions by the compression spring 60, and the face portion 58 is seated on the valve seat at the lower end of the fourth oil passage 22, thereby closing the fourth oil passage 22. The upper end of the chamber 57 communicates with the lower end of the chamber 57 via a hole 61 in the supply valve 59.

The upper end of the needle valve 66 in the nozzle/L155 is the spring chamber 6
4 and is biased downward by a compression spring 65 within a spring chamber 64. The spring chamber 64 is connected to the 6th/111th passage 21 and is connected to the 6th/111th passage 21.

Next, the operation will be explained. Figure 1 shows when current is applied to the solenoid with diameter /L/8 (fuel injection feeding), and the signal path 7 is connected from the output terminal 6 of the microcomputer 5 to the signal path 7 at a predetermined timing when Vcg is applied during 10 revolutions of the engine. A signal is sent to the coil/L/8, and the coil 8 is energized for a predetermined time. The injection amount is determined by the energization time to the coil 8 as follows. That is, while the engine 1 is operating, hydraulic oil at a predetermined pressure is constantly supplied to the hydraulic oil inlet 14 by the operation of the hydraulic oil supply system S2, and in this state, the coil/I/8 is energized and the active core 28 When the spool valve 26 rises to the top dead center position in FIG. 1 against the zero elasticity of the spring 29, the spool valve 26 also rises following the active core 28 due to the elasticity of the solenoid spring 27. At the same time as blocking the first oil passage 17 as shown in FIG.

The first oil passage 17' is connected to the outlet 61 via the outer circumferential groove 60. As a result, the hydraulic pressure in the switching valve chamber 19 disappears, and the differential switching valve 41 rises against the elasticity of the spring 42 due to the hydraulic pressure in the inlet port 14.
8. At the same time as 18' is shut off, the conical valve seat 20 is opened (second switching position @). As a result, the hydraulic oil in the inlet 14 flows into the servo piston chamber 46 through the hole 47, and the servo piston 50 is activated. The plunger 52 is pushed down through the opening. The fuel oil in the plunger chamber 51 is supplied to the nozzle oil reservoir chamber 56 through the oil passage 54, pushes up the needle valve 66 against the elasticity of the spring 65, and is ejected from the nozzle 55. During this time, the supply valve 59 keeps the fourth oil passage 22 closed due to the elasticity of the spring 600 and the pressure of the fuel oil.

After the predetermined energization time has elapsed, the upward suction force by the carp/l/8 disappears, and the active core 28Vi spring 2
The elastic lever 9 lowers the spout V valve 26 as shown in Figure 2.
is pushed down by the active core 28 (first switching position), and then the first oil passage 17, 17' communicates via the outer circumferential groove 60, and the switching valve chamber 19 receives pressurized pressure inside the inlet 14. Oil is supplied, the hydraulic pressure acting on the switching valve 41 is canceled out, the switching valve 41 is lowered by the elasticity of the spring 42, and the face portion 44 is seated on the valve seat 2o, and at the same time, the second valve 18, 18' is Communication occurs via the outer circumferential groove 48, and therefore the pressurization within the servo piston chamber 46 disappears. Therefore, the supply valve 59 is lowered by the fuel oil pressure in the fourth oil passage 22 against the elasticity of the spring 600, and the pressurized fuel oil in the fuel inlet 14a is filled into the plunger chamber 51. As described above, FIG. 2 shows the time when the current to the solenoid coil 8 is cut off (fuel charging stroke).

As explained hereafter, in the present invention, the servo piston 50 for actuating the plunger 52 of the injector and the servo piston chamber 46 into which the servo piston 5o is fitted are connected to the hydraulic pressure source (hydraulic oil inlet 14) and the hydraulic oil outlet. 24 (a differential type switching valve 41 and a pilot spout to valve 26 that selectively connects the switching valve chamber 19 to the working surface hydraulic pressure source and the hydraulic oil outflow valve 24); A solenoid active core 28 connected to a switching valve mechanism and a fuel oil supply mechanism (fuel oil supply system S, Ja
), and is configured so that the servo piston 50 is operated by hydraulic oil by applying and interrupting current to the solenoid, and the following effects can be expected.

(1) Operation failure of the pilot valve (spool valve 26) and main valve (switching valve 41) when low-heavy oil is used as fuel oil, i.e., operation resistance holes due to high viscosity, increased wear, sticking, It is possible to prevent deterioration of operating characteristics due to temperature rise of the solenoid part due to fuel heating.

(2) When the spool valve 26 is used as the pilot valve, the hydraulic load when opening and closing the valve is smaller than that of a poppet valve, and the movement stroke of the spool valve 2 can be set small, so the pilot valve (spool valve 26) The speed also increases. Since the inlet/outlet area of the spool valve 26 can be set larger than that of a poppet valve, the response of the main valve (1/l switching valve 41) and servo piston 50 is fast, and the temperature rise of the solenoid (coil 8) is small. , it becomes easy to take countermeasures against temperature rise. Furthermore, if an adjustment bolt 67 is used as shown in the drawings of the embodiment, the stroke of the spool valve 26 can be easily set. Further, since both ends of the spool valve 26 are in communication with the oil passage 36, the operation of the spool valve 26 becomes smooth. Since the oil leaking from the spool valve 26 moves inside the solenoid, it is effective in preventing wear and cooling the solenoid moving parts.

6 and 4 show another embodiment in which the solenoid active core 28 in FIGS. 1 and 2 rises when the coil 8 is energized, but descends when the coil 8 is energized.
Figure 6 shows the current-carrying material injection stroke when AE is energized to the solenoid, and Figure 4 shows the state when current is cut off to the solenoid (fuel filling stroke). Symbols indicate corresponding parts.

[Brief explanation of the drawing]

Fig. 1 is a schematic structural diagram of the electro-hydraulic control fuel injection system according to the present invention (when current is applied to the solenoid), Fig. 2 is a vertical sectional view of the injector when current is cut off to the solenoid, and Fig. 6 is FIG. 4 shows another embodiment of the first embodiment.
, a drawing corresponding to FIG. 2. 8...Carp/I/(
solenoid), 19... switching valve chamber, 24...
Hydraulic oil outlet, 26. 41... Spool valve, actuated switching valve (switching valve mechanism), 28... Active core, 46
... Servo piston chamber, 50... Servo piston,
52.-- Plunger, courtesy... Hydraulic oil supply system,
S, l...Fuel oil supply system bS9...Injector Patent applicant Yanmar Diesel Co., Ltd. agent #
Buried soil Tadaka Omori ・, ); 11. ,'l',
::: ! . t'j Figure 2 jδ' = 71 II Section 4 -350-

Claims (2)

[Claims] (1) A servo piston for actuating the plunger of the injector, a switching valve mechanism that selectively connects the servo piston chamber in which the servo piston is fitted to a hydraulic oil pressure source and a hydraulic oil outlet, and a solenoid connected to the switching valve mechanism. A fuel injection device comprising an active core and a fuel oil supply mechanism to a plunger chamber, and a servo piston is operated by hydraulic oil by energizing and cutting off current to a solenoid. (2) a differential type switching valve in which the switching valve mechanism selectively connects the servo piston chamber to a hydraulic oil pressure source and a hydraulic oil outlet;
It consists of a pilot spool valve that selectively connects the switching valve chamber to a hydraulic oil pressure source and a hydraulic oil outlet, and the spool valve connects to the hydraulic oil hydraulic source through a first oil passage that is opened and closed in its outer groove. The switching valve chamber is connected, and the servo piston chamber and the hydraulic oil outlet are connected via a second oil passage that is opened and closed by the outer circumferential groove of the switching valve, and the switching valve opens the hydraulic oil pressure only when the first oil passage is opened. 2. The fuel injection device according to claim 1, wherein the source and the servo piston chamber are cut off and the second oil passage is opened.