JPS5941659A - Fuel injection unit - Google Patents

Abstract

PURPOSE:To obtain engine operation without any malfunction by installing a working oil supply system, which operates a servo piston for an injector plunger, separately from a fuel feeding system, which is provided with an independent fuel flow rate control mechanism. CONSTITUTION:An injector, in which a spool valve 26 is inserted into a spool valve chamber 23 within an injector body 13, lowers the 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 a valve chamber 23 via a fuel 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 pistion chamber 46 to lower a servo pistion 50. With this contrivance, fuel, which has been supplied from a fuel feeding system to a fuel passage 54 via a fuel control system S2b, a fuel passage 12b, 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 that is suitable for an electro-hydraulic control system, and it reduces the energization time of an injector coil and prevents deterioration of solenoid characteristics (delay in operation time) due to coil temperature rise. , reduction in acting force, etc.).

Operation failure of pilot valve and main valve when using low-heavy fuel oil, such as high operating resistance due to high viscosity, increased wear, sticking, and deterioration of operating characteristics due to temperature rise of the solenoid due to fuel heating. It is also a part of the purpose of the present invention to prevent this, to reduce the load on the solenoid to reduce changes in solenoid characteristics due to temperature rise, and to speed up the response of the servo piston.

Conventionally, an electro-hydraulic control fuel injection device includes a switching valve mechanism such as a pilot valve and a main valve in an injector, and a solenoid active core connected to the switching valve mechanism.
In a device that is equipped with a servo mechanism for operating a plunger and operates a servo piston by energizing the solenoid and cutting off the current b1ε, the injection amount is controlled only by the energization time or cutoff time of the solenoid coil of the injector. . However, in this case, there is a problem that the coil is energized for a long time and the injection characteristics change due to changes in the solenoid characteristics due to temperature rise. Conventionally, systems in which the flow rate to the servo piston is directly controlled using a spool valve have already been proposed (for example, Utility Model Application Publication No. 57-80656; Japanese Patent Application Publication No. 57-80656).
5-49571). In this case, Totoro uses a spool valve to control the flow rate to the servo piston, so there is a problem that the spool valve cannot have a large flow area.

Furthermore, conventionally, in an electro-hydraulic control fuel injection device having a structure in which the injector has a switching valve mechanism such as a pilot valve and a main valve, and a servo mechanism for operating the plunger, the hydraulic oil supply system and the fuel oil supply system are separated. There is no built-in 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. Failure (poor response, abnormal wear, sticking, etc.)
In addition, a decrease in the operating force and operating speed of the solenoid due to heating to avoid viscosity reduction becomes a problem.

The present invention provides an electro-hydraulic control fuel injection system in which a hydraulic oil supply system and a fuel oil supply system are provided separately, and a fuel oil amount control mechanism is provided independent of one injector. This is an attempt to avoid the above-mentioned conventional problems by controlling the amount of fuel oil separately from the injector without controlling the amount.

In Figure 1, which shows when current is applied to the solenoid (fuel injection stroke), 1 is the engine, So is the electric control system,
S2 is a hydraulic oil supply system, S2a is a fuel oil supply system, S2b is a fuel oil control system, and S3 is an injector system. In the electrical control system S□,
A rotational phase angle sensor 8 is opposed to the 7th gear/I/2 of the engine 1, and the sensor 8 is connected to the microcomputer 5 via the signal path 4. The output terminals 6 corresponding to each cylinder of the microcomputer 6 are The fuel control terminal 6a is connected to the coil (solenoid) V8 (solenoid) in the injector system S3 via the signal path 7, and the fuel control terminal 6a is connected to the coil/l/70 in the fuel oil control system S2b via the signal path 7a.

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.
0 is connected to a hydraulic oil tank 11Vc, and an oil passage 12 above the discharge port of the pump 9 is connected to a hydraulic oil inlet 14 (hydraulic source) K of the injector body 13. A pressure regulating valve 15 is disposed in parallel with the pump 9, and thereby the oil passage 12
The oil pressure inside is maintained at a constant value. Further, 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.

In the fuel oil supply system S2a, there is a fuel supply pump 9a driven by the engine 1, the suction port of the pump 9a is connected to the fuel tank 11a via a filter 10a, and the discharge port of the pump 9a is connected to a solenoid via an oil path 12a. It is connected to the inflow lower 2 of the valve body 71. A solenoid coil valve 74 is fitted into a solenoid valve chamber 73 communicating with the inflow lower 2 so as to be able to rise and fall freely, and the valve 74 is connected to an active core 75 and is urged downward by a solenoid spring 76 to normally close the valve seat 77. are doing. Outflow lower 8 communicating with valve seat 77 is connected to fuel inlet 14a of injector body 18 via oil passage 12b. 79 is Ajanuto Bolt, 80 is Natsuto. This fuel oil control system 82″b is configured such that when current is applied to the carp fi 776, the core 75 is drawn upward, the valve seat 77 opens, and fuel oil proportional to the energization time passes through the valve seat 77. A pressure regulating valve 15a is arranged in parallel with the bomb 9a, forming a collecting pipe that performs a pressure control function.

Inside the injector body 13, the hydraulic oil inlet 1
4 has a first oil passage 17 (part of which has an angle of 17 degrees) and a switching valve chamber 19 that both open downward 7, and a conical valve seat 20 and an eighth oil passage 21 that are in the same window as the switching valve chamber 19. Both are open upward. , the first oil passage 17, 17' is the spool valve chamber 23
7 upper end of the switching valve chamber 19 through the inflow "114
The second oil passage 18 (partly designated as 18") located at a position that does not communicate with the servo piston chamber 46 and the switching valve chamber 19 and the outlet 2
4 and is connected to the discharge oil path 25. 2nd 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 28 so as to be able to move up and down, and is urged upward by a solenoid spring 27 compressed between the bottom of the spool valve chamber 28 and the spool valve 26, and is surrounded by a solenoid coil A/8. active core 28
The core 28 is in contact with the solenoid valve spring 29.
It is held at the upper end position against zero elasticity. Spool valve 2
6: The outer circumferential groove 8o provided at the middle height portion is connected to the first oil passage 17.
The spring chamber 32 below the spool valve 26 is connected to the spool valve chamber 26 through an oil passage 33.
It is connected to the upper end of the core chamber 35 and communicates with the upper end of the core chamber 35 through the hole 34 in the body 13, the core chamber 85, and the hole 36 in the core 28. The spring 29 is fitted onto the outer periphery of the upper end of an adjustment bolt 37 which also serves as a stopper, is screwed onto the upper end of the adjustment bolt body 13, and is locked by a nut 88. A hole 39 in the center of the adjustment bolt 37 connects the upper end of the core chamber 85 to the discharge oil passage 25 VC.

Inside the switching valve chamber 19 is a cup-shaped differential switching valve 41 that opens upward.
is slidably fitted into the upper end 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 43, and further decreases in diameter at the conical face 44 near the lower end. is formed. The face portion 44 is a portion on which the conical valve seat 2O is seated, and the ridge portion 45 is a portion that fits into a hole 47 connecting the valve seat 2o and the servo piston chamber 46 with a slight gap. The outer circumferential groove 48 of the switching valve 41 is connected to the second oil passages 18, 18 in the state shown in FIG.
' is blocked.

A plunger 52 in a plunger chamber 51 is connected (abutted or fixed) to the servo piston 5° in the servo piston chamber 46. The lower end of the servo piston chamber 4.6 is connected to the discharge oil passage 25aK through the outlet 58.

The lower end of the plunger chamber 51 passes through the fuel oil passage 54/Z w5
5, and also connected to the lower end of a supply valve chamber 57 parallel to the plunger chamber 51.

The lower end of the valve chamber 57 is connected to the fuel inlet 14a via the fourth oil passage 22, and a downwardly opening cup-shaped supply valve 59 having a conical face portion 58 at the upper end is fitted into the chamber 57, and a compression spring is connected to the valve chamber 57. 60 , the face portion 58 is seated on the valve seat at the lower end of the fourth oil passage 22 and closes the fourth oil passage 22 . The lower 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 68 within the nozzle 55 protrudes into the spring chamber 64 and is biased downward by a compression spring 65 within the spring chamber 64 . The spring chamber 64 is connected to the eighth oil passage 21 .

Next, the operation will be explained. Figure 1 shows solenoid carp/1/8
This figure shows when current is applied to (fuel injection stroke), and at a predetermined timing while the engine 1 is rotating, it passes from the output terminal 6 of the microcomputer 5 through the signal path γ to the carp/I/8.
A signal is sent to the carp/V 8 K for a predetermined period of time. However, the energization time to the coil 8 is controlled to be as short as possible in accordance with the amount of fuel oil being supplied from the fuel oil control system s, b to the plunger chamber 51. That is, in the fuel oil control system S2b, the amount of fuel oil supplied to the plunger chamber 51 via the oil passages 12a and 12b is determined according to the operating state of the engine depending on the energization time to the coil 7o, and the amount of fuel oil supplied to the plunger chamber 51 is determined according to the operating state of the engine. The solenoid coil/I/8 is energized for the shortest time commensurate with the amount of fuel oil added. That is, while the engine 1 is operating (due to the operation of the bow hydraulic oil supply system S2, hydraulic oil at a predetermined pressure is constantly supplied to the hydraulic oil inlet 14, and in this state, the coil/L/8 is energized and activated. When the core 28 rises in the direction of the arrow to the top dead center position in FIG. K shuts off the first oil passage 17 as shown in Fig. 1, and connects the first oil passage 11° to the outlet 31 via the outer circumferential groove 80.
Since the hydraulic pressure in 9 disappears, the differential type switching valve 41 switches to the inlet 1.
The spring 420 rises against the elastic force due to the oil pressure in the valve 4, and the switching valve 41 closes off the second oil passage 18.18' and at the same time opens the conical valve seat 20 (second switching position). As a result, the hydraulic oil in the 66 cylinder 14 flows into the servo piston chamber 46 through the hole 47, and pushes down the plunger 52^1A via the servo piston 50. The fuel oil in the plunger chamber 51 flows through the oil passage 54.
The oil is supplied to the nozzle oil reservoir chamber 56, pushes up the needle valve 68 against the elasticity of the spring 65, and is ejected from the nozzle 55. Meanwhile, the supply valve 59 is operated by the spring 6.
The fourth oil passage 22 is closed due to the elasticity of 0 and the pressure of the fuel oil 2 (
keep it in good condition.

After the predetermined energization time has passed, the upward suction force by the carp/1/8 disappears, and the active core 28u and x-pring 2
90 is lowered by elasticity as shown in Fig. 2, and the spool valve 26
is also tilled by the active core 28 and descends (first
switching position). Then, the first oil passage 17.17° communicates with each other through the outer circumferential groove 80, 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. , the switching valve 41 due to the elasticity of the spring 420
is lowered and the face portion 44 is seated on the valve seat 20 VC, and at the same time, the second oil passage 18.18° is communicated via the outer circumferential groove 48, so that the oil pressure in the servo piston chamber 46 disappears. Therefore, the fuel oil pressure in the fourth oil passage 22 causes the Xabli valve 59 to move downward against the elasticity of the spring 600, and the plunger chamber 51 is filled with the pressurized fuel oil in the fuel inlet 14a. As described above, FIG. 2 shows the time when the current to the solenoid carp/L'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 field source (hydraulic oil inlet 14) and the hydraulic oil outlet 24. a switching valve mechanism (a differential type switching valve 41 and a pilot spool valve 26 that alternatively connects the switching valve chamber 9 to a hydraulic oil pressure source and a hydraulic oil outlet); A solenoid active core 28 connected to the switching valve mechanism and a fuel oil supply mechanism (fuel oil supply system A S2) to the plunger chamber 51
a) and a fuel oil amount control mechanism (fuel oil control system 52b) independent of the injector system S3, and is configured to operate the servo piston 50 using hydraulic oil by applying and interrupting current to the solenoid. , the following effects can be expected.

(1) The time for energizing the injector Coil/L/8 is reduced, and deterioration of solenoid characteristics (delay in activation time, decrease in acting force, etc.) due to the rise of the Coil/I/8 is reduced.

(2) When using low-heavy fuel oil, the pilot pulp (spool valve 26) fx and main valve (
It is possible to prevent operational failures of the switching valve 41), such as large operating resistance due to high viscosity, increased wear, sticking, and deterioration of operating characteristics due to temperature rise of the solenoid due to fuel heating.

(3) 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. 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 (Koi/l/8) is small,
Measures against temperature rise become easier. In addition, as shown in the drawings of the embodiment, if the assist stop port 87 is adopted, the metro of the Nupur valve 26
settings are easier. Also, since both ends of the spool valve 26 are in communication with the oil passage 331, 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.

FIGS. 8 and 4 are another embodiment in which the solenoid active core 28 in FIGS. 1 and 2 is raised when energized to the coil/I/8, but lowered when energized. Figure 3 shows when current is applied to the solenoid (fuel injection stroke)
, Figure 4 is when the current to the solenoid is cut off (fuel filling process)
The same reference numerals as those in FIGS. 1 and 2 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 cross-sectional view of the injector when current is cut off to the solenoid, Figs. FIG. 1/:, t: A drawing corresponding to FIGS. 1 and 2 showing another embodiment. 8... Coil (solenoid), 19... Switching valve chamber, 24... Hydraulic oil outlet, 26.4]... Spool valve, actuated switching valve (switching valve mechanism), 28... Active core, 46・
...Servo piston chamber, 5o...Servo piston, 5
2... Blunger, S2... Hydraulic oil supply system,
S2a...Fuel oil supply system, S2b...Fuel oil control system, S3...Injector Patented
Applicant: Yanmar Diesel Co., Ltd. JP-A-59-4
1659 (7) 2 drawing procedural amendment (Hakuwa 1. Indication of the case Showa, S7 year Takekugo Gan No. /♂2≠J&No. 2, Hiiragi Akira's name Double 1 Kenkan Gonjiri 3, Person making the amendment Relationship to the case Special?F Applicant 4,
Agent 5, Date of amendment order (Date of dispatch) Month, Showa
Day 6, Subject of amendment Description 7, Contents of amendment Engraving of the description (no change in content). 8 List of attached documents Specification 1 copy or more”2

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. Features include an active core, a fuel oil supply mechanism to the plunger chamber, and a fuel oil amount control mechanism independent from the injector, and the servo piston is operated by hydraulic oil by energizing and cutting off current to the solenoid. Fuel injection device. (2) A differential type switching valve in which the switching valve mechanism selectively connects the servo piston chamber to the hydraulic oil pressure source and the hydraulic oil outlet; The spool valve connects the hydraulic oil pressure source and the switching valve chamber via the first oil passage that is opened and closed in the groove on its outer periphery, and the switching valve The second one opens and closes with a groove.
The servo piston chamber and the hydraulic oil outlet are connected via an oil passage, and only when the first oil passage is opened, the switching valve shuts off between the hydraulic oil pressure source and the servo piston chamber, and the second oil passage is opened. A finishing material injection device according to claim 1.