JPS6314186B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine suitable for an electro-hydraulic control system, and is designed to prevent malfunction of pilot valves and main valves when using low-heavy fuel oil. 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. It is also a part of the purpose of the present invention to reduce the load on the solenoid to reduce changes in solenoid characteristics due to temperature rise, and to increase the responsiveness of the servo piston.

Conventionally, in an electro-hydraulic controlled fuel injection system, in which the injector has a switching valve mechanism such as a pilot valve and a main valve, and a servo mechanism for operating a plunger, a hydraulic oil supply system and a fuel oil supply system are provided separately. There is no structure. However, when low-heavy oil is used as fuel oil, it has high viscosity and abnormal wear components (sludge, etc.) of the fuel injection device are mixed into the fuel oil, causing problems with the operation of the pilot valve, main valve, and servo mechanism of the solenoid. Problems include failures (poor response, abnormal wear, sticking, etc.) and reductions in solenoid operating force and operating speed due to heating to avoid viscosity reduction.

The present invention provides an electro-hydraulic control fuel injection device, which includes:
The above conventional problem is avoided by providing a hydraulic oil supply system and a fuel oil supply system separately, which will be explained next with reference to the drawings.

In Figure 1, which shows when current is applied to the solenoid (fuel injection stroke), 1 is the engine, S ₁ is the electric control system, S ₂ is the hydraulic oil supply system, S ₂ a is the fuel oil supply system, and S ₃ is the injector. It is a system. In the electric control system S ₁ , the flywheel 2 of the engine 1 is equipped with a rotational phase angle sensor 3.
The sensor 3 is connected to the microcomputer 5 via a signal path 4, and the output terminal 6 corresponding to each cylinder of the microcomputer 5 is connected to the coil 8 (solenoid) in the injector system S ₃ via a signal path 7. ).

There is a supply pump 9 driven by the engine 1 in the hydraulic oil supply system S ₂ , the suction port of the pump 9 is connected to the hydraulic oil tank 11 via a filter 10 , and the discharge port of the pump 9 is connected to the oil path 12 . Hydraulic oil inlet 14 of injector turbo day 13 (hydraulic source)
is connected to. Pressure regulating valve 1 in parallel with pump 9
5 is arranged, whereby the oil pressure in the oil passage 12 is maintained at a constant value. 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.

Inside the fuel oil supply system S ₂ a, there is a fuel supply pump 9a driven by the engine 1.
The suction port of the fuel tank 1 passes through the filter 10a.
1a, and the discharge port of the pump 9a is connected to the oil passage 12a.
through the fuel inlet 1 of the injector turbo day 13
Connected to 4a. A pressure regulating valve 15a is disposed in parallel with the pump 9a, which allows the fuel oil path 12
The fuel oil pressure of a is maintained at a constant value. Further, an accumulator 15a is connected to the fuel oil passage 12a, or a part of the oil passage 12a forms a collecting pipe that functions as an accumulator.

In the engine turbo day 13, a first oil passage 17 (a part of which is designated as 17') and a switching valve chamber 19 are both opened downward at the hydraulic oil inlet 14, and are coaxial with the switching valve chamber 19. The conical valve seat 20 and the third
Both oil passages 21 are open upward. The first oil passages 17, 17' are connected to the upper end of the switching valve chamber 19 via the spool valve chamber 23, and the second oil passage 18 (partly designated as 18') at a position that does not communicate with the inlet 14 is
Switch the servo piston chamber 46 between the valve chamber 19 and the outlet 2
4 and is connected to the discharge oil path 25. The second oil passages 18, 18' are opened and closed by an outer circumferential groove 48 of the switching valve 41.

A spool valve 26 is fitted into the spool valve chamber 23 so as to be able to rise and fall freely, and a solenoid spring 27 is contracted between the bottom surface of the spool valve chamber 23 and the spool valve 26.
The core 28 is urged upward by the solenoid coil 8 and comes into contact with the active core 28 surrounded by the solenoid coil 8 to hold the core 28 at the upper end position against the elasticity of the solenoid valve spring 29. An outer circumferential groove 30 provided at the intermediate height of the spool valve 26 connects the first oil passage 17' to the outlet 31. The lower spring chamber 32 of the spool valve 26 is connected to the upper end of the spool valve chamber 23 via an oil passage 33, and is further connected to the upper end of the spool valve chamber 23 through a hole 34 in the body 13, a core chamber 35, and a hole 36 in the core 28. It communicates with the upper end of the core chamber 35. The spring 29 is an adjustment bolt 37 that also serves as a stopper.
Adjustment bolt 3 is fitted around the outer circumference of the lower end of
7 is screwed into the upper end of the body 13 and locked by a nut 38. The center hole 39 of the adjuster bolt 37 drains the upper end of the core chamber 35 into the oil passage 2.
Connected to 5.

A top-opening cup-shaped differential type switching valve 41 is slidably fitted in the switching valve chamber 19, and a spring 42 is compressed between the upper end surface of the switching valve chamber 19 and the switching valve 41.
is urged downward by. The outer diameter of the lower half of the switching valve 41 decreases from the pressure shoulder 43 as a boundary, and further decreases in diameter as it goes downward at the conical face 44 near the lower end, and a small-diameter constricted portion 45 is formed below. ing. The face portion 44 is a portion that seats on the conical valve seat 20, and the throttle portion 45 is a portion that fits into a hole 47 connecting the valve seat 20 and the servo piston chamber 46 with a slight clearance. The outer circumferential groove 48 of the switching valve 41 blocks the second oil passages 18, 18' in the state shown in FIG. 1 (second switching position to be described later).

Servo piston 50 in servo piston chamber 46
A plunger 52 in a plunger chamber 51 is connected (contacted or fixed) to the plunger 52 . The lower end of the servo piston chamber 46 passes through the outlet 53 to the discharge oil passage 25.
Connect to a.

The lower end of the plunger chamber 51 is connected to a nozzle oil reservoir chamber 56 of a nozzle 55 through a fuel oil passage 54, and is 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 the fourth
Connected to the fuel oil inlet 14a via the oil passage 22,
A downward-opening cup-shaped supply valve 59 having a conical face portion 58 at its upper end is fitted into the chamber 57 and is urged upward by a compression spring 60. The fourth oil passage 22 is blocked by the driver sitting there. The upper end of the chamber 57 is connected to the chamber 57 through a hole 61 in the supply valve 59.
It communicates with the lower end of.

The upper end of the needle valve 63 within the nozzle 55 protrudes into the spring chamber 64 and is biased downward by a compression spring 65 within the spring chamber 64 . Spring chamber 64
is connected to the third oil passage 21.

Next, the operation will be explained. FIG. 1 shows when current is applied to the solenoid coil 8 (fuel injection stroke), and a signal is sent from the output terminal 6 of the microcomputer 5 to the coil 8 via the signal path 7 at a predetermined timing while the engine 1 is rotating. The coil 8 is energized for a predetermined period of time. The injection amount is determined by the energization time to the coil 8 as follows. That is, during operation of the engine 1, 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 8 is energized and the active core 28 is activated by the spring. When the spool valve 26 rises in the direction of the arrow to the top dead center position in FIG. Oil road 1
7 as shown in Figure 1, and the first oil passage 1
7' is connected to the outlet 31 via the outer circumferential groove 30.
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.
simultaneously blocks the second oil passages 18, 18' and opens the conical valve seat 20 (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 pushes down the plunger 52 via the servo piston 50. The fuel oil in the plunger chamber 51 passes through the oil passage 54 to the nozzle oil reservoir chamber 5.
6, the needle valve 63 is connected to the spring 65
The liquid is pushed up against the elasticity of the liquid and ejected from the nozzle 55. Meanwhile, the supply valve 59 is held by the spring 60.
The fourth oil passage 22 is kept closed by the elasticity of the oil and the pressure of the fuel oil.

When a predetermined energization time has elapsed, the upward attraction force by the coil 8 disappears, and the active core 28 descends as shown in FIG. 2 due to the elasticity of the spring 29.
The spool valve 26 is also pushed down by the active core 28 (first switching position). Then, the first oil passages 17, 17' communicate through the outer circumferential groove 30, the pressurized hydraulic oil in the inlet 14 is supplied to the switching valve chamber 19, and the hydraulic pressure acting on the switching valve 41 is offset.
Due to the elasticity of the spring 42, the switching valve 41 is lowered and the face portion 44 is seated on the valve seat 20, and at the same time, the second oil passages 18, 18' are communicated via the outer circumferential groove 48.
Therefore, the oil pressure in 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 60, and the fuel inlet 14 is moved into the plunger chamber 51.
A is filled with pressurized fuel oil. In this way the second
The figure shows when the current to the solenoid coil 8 is cut off (fuel filling process).

As explained above, 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 50 is fitted are connected to the hydraulic oil pressure source (the hydraulic oil inlet 1
4) and a switching valve mechanism (for pilots that selectively connects the differential type switching valve 41 and the switching valve chamber 19 to the hydraulic oil pressure source and the hydraulic oil outlet 24) A spool valve 26), a solenoid active core 28 connected to a switching valve mechanism, and a fuel oil supply mechanism (fuel oil supply system S ₂ a) that supplies low heavy oil to the plunger chamber 51. The servo piston 50 is configured to be operated using hydraulic oil different from fuel oil by applying and interrupting current, 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 fuel oil is used, i.e., high operating resistance due to high viscosity, increased wear, sticking, and fuel heating. It is possible to prevent deterioration of operating characteristics due to temperature rise of the solenoid part.

(2) Since 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. Furthermore, since the movement stroke of the spool valve 26 can be set small, the speed of the pilot valve (spool valve 26) can also be increased. Since the inlet/outlet area of the spool valve 26 can be set larger than that of the poppet valve, the response of the main valve (switching valve 41) and the servo piston 50 is fast. Furthermore, since the temperature rise of the solenoid (coil 8) is small, countermeasures against temperature rise can be easily taken. Further, if an adjusting bolt 37 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 communicated through the oil passage 33, the operation of the spool valve 26 becomes smooth. Since oil leaking from the spool valve 26 flows through the inside of the solenoid, it is effective in preventing wear and cooling the moving parts of the solenoid.

3 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 3 shows the state when current is applied to the solenoid (fuel injection stroke), and Figure 4 shows the state when current is cut off to the solenoid (fuel filling stroke). The same symbols as those in Figures 1 and 2 refer to corresponding parts. It is.

[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 longitudinal cross-sectional view of the injector when current is cut off to the solenoid, and Figs. The figures correspond to FIGS. 1 and 2 to show another embodiment. 8...Coil (solenoid), 19...Switching valve chamber,
24... Hydraulic oil outlet, 26, 41... Spool valve,
Differential switching valve (switching valve mechanism), 28...active core, 46...servo piston chamber, 50...servo piston, 52...plunger, S ₂ ... hydraulic oil supply system, S ₂ a... fuel oil supply system, S ₃ ...Injector.

Claims (1)

[Claims] 1 A switching valve mechanism that selectively connects the servo piston 50 for actuating the plunger 52 of the injector and the servo piston chamber 46 in which the servo piston is fitted to the hydraulic oil pressure source and the hydraulic oil outlet 24, and the switching valve mechanism is connected to the switching valve mechanism. The servo piston 50 is equipped with a solenoid active core and a fuel oil supply mechanism that supplies low heavy oil to the plansha chamber, and operates the servo piston 50 with a hydraulic oil different from the fuel oil by supplying and interrupting current to the solenoid. , the switching valve mechanism is connected to the servo piston chamber 46 and the hydraulic oil pressure source 14 is connected to the servo piston chamber 46.
a differential plunger type switching valve 41 that selectively connects the switching valve chamber 19 to the hydraulic oil pressure source and the hydraulic oil outlet 24; and a pilot spool valve 26 that selectively connects the switching valve chamber 19 to the hydraulic oil pressure source and the hydraulic oil outlet 24. consists of spool valve 2
6 connects the hydraulic oil pressure source 14 and the switching valve chamber 19 via the first oil passage 17 which is opened and closed by its outer circumferential groove 30, and the switching valve 41 connects the second oil passage 18 which is opened and closed by its outer circumferential groove 48. The servo piston chamber 46 and the hydraulic oil outlet 24 are connected through the servo piston chamber 46 and the hydraulic oil outlet 24, and only when the first oil passage is opened, the switching valve cuts off between the hydraulic oil pressure source and the servo piston chamber, and the second oil passage is opened. A low heavy oil fuel injection device characterized by: