JPS6235050A - Fuel injection valve for diesel engine driven by gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention has a pressurized gas inlet, and the inlet and
an elongated housing having a duct between one or more nozzle holes at the front end of the injection valve facing the combustion constriction of the engine cylinder, said gas duct being controlled by a valve member cooperating with a seat of the injection valve housing; , of the type in which the valve member is actuated in the direction towards the seat by a biased closing spring and in the opposite direction by periodically applied servo oil pressure. Regarding injection valves.

[Conventional technology and its problems]

Diesel engines that use gas as fuel are of particular interest as propulsion engines for gas tankers, especially for the transport of liquid natural gas (LNG), and the amount of gas that inevitably evaporates from the cargo can be reduced by diesel engines to a high degree of efficiency. used in However, this type of engine can still be advantageously applied in stationary installations and also serves as a driving force for a generator.

Regardless of the field of application of the engine, it is a natural requirement that, as far as possible, the inherent danger of gas explosions in the engine be already eliminated by the construction of the engine. Fierce explosions occur especially when the gas valve member of the cylinder's injector becomes completely or partially stuck in its position and, with it, the oxygen concentration in the cylinder This is the case when a considerable amount of gas is injected during the working cycle.

The unburned gases flowing from the cylinder are later mixed with the hot combustion gases and are naturally present somewhere in the exhaust system where it comes into contact with free oxygen present in the exhaust gases from a second normally working cylinder, for example. can be expected to ignite. Particularly if the ignition takes place in the exhaust receiver, an instantaneous pressure rise of significant explosive nature occurs, thereby causing serious damage.

In order to prevent the above-mentioned situation, it is desirable to provide the valve with a strong closing spring, and at the same time the risk of fatigue fracture is very small, since the corresponding stress in the spring material is relatively low. However, this desire often conflicts with the space limitations of the engine's cylinder cover, particularly with respect to uniflow engines, where the central exhaust valve of the cylinder cover occupies a significant portion of the available planar area.

[Purpose of the invention]

The object of the invention is to provide an injector that combines moderate space requirements with a high degree of certainty that the gas valve always closes completely and at defined times of the working cycle.

[Means for solving problems]

With respect to the above, it is a feature of the invention that a chamber in permanent communication with the gas duct is provided in the injection valve housing, the chamber being axially displaceable in force-transmitting connection with the valve member. The front part is sealed and partitioned by a piston.

[For production]

What is thereby obtained under normal operation of the engine is that the valve member is connected by two cooperating forces, namely partially by the closing spring and partially by the supply connected to the gas inlet of the injection valve. Due to the relatively high pressure continuously prevailing in the system and thus also in the gas duct of the injection valve, it is often the case that a pressure of approximately 200 bar is momentarily applied in the closing direction. The closing spring can therefore be dimensioned according to relatively low pressing forces and/or relatively low internal stresses, resulting in smaller spring dimensions and/or caused by highly variable influences exerted on the valve spring. Increased safety against fatigue damage. Furthermore, closing the valve at the moment when the pressure in the servo oil acting in the opening direction ceases is safe even in the case of a spring break. The invention provides, inter alia, for such a precautionary measure suitable for opening and closing a check valve and thereby interrupting the supply of gas to one or more injection valves of a cylinder in the event of an abnormally high gas flow. As a supplement, the precautionary measure, on the other hand, does not prevent at least a portion of the gas flow downstream of the closed check valve from leaking into the engine cylinder.

The structure is 1lJt! In one and therefore generally preferred embodiment of the invention, the piston is integral with the rear end of the valve member.

However, it is clear that the advantageous effects described above can still be achieved with a separate piston that rests directly or indirectly on the rearwardly facing surface of the valve member.

According to the invention, a closing spring can be housed in a chamber between the fixed wall of the housing and the rear side of the piston, and then the injection valve projects outside the engine cylinder when the injection valve is installed. The chamber can be formed in the valve part. That embodiment is particularly suitable, for example in uniflow engines with a central exhaust valve and several injector valves distributed along the periphery of the combustion chamber, which are mounted in the cylinder cover due to space conditions. It may be desirable to have the outer diameter of the forward portion of the injector housing as small as possible.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The fuel injection valve shown in Figures 1 to 3 consists of a slender front part 1 that is housed in the cylinder cover 2 of the engine, a central part 3 with a slightly larger diameter, and bolts that fasten the injection valve to the cylinder cover. Continuous hole 5 (for receiving the
3).

A threaded connection 6 fixed in the center of the head 4 is connected to high pressure from a source, e.g. a conventional fuel pump of the Bosch type, for periodically discharging a defined amount of ignitable pilot oil into the injection valve. It is designed to be connected to the duct.

A υ control or a servo oil inlet lower for opening the gas valve of the injection valve, which will be described later, is formed in the head 4 together with a corresponding inlet 8, and this population 8 is connected to the opening of the gas valve of the injection valve. Sometimes connected to a normally continuously open conduit supplying high pressure gas from a suitable source for injection into the engine cylinders.

Combustion chamber 10 of the engine cylinder from the face end of the housing 1
The injector 9 protruding into the interior has two sets of nozzle holes 11 and 1 for injecting pilot oil and gas, respectively.
It has 2. The nozzle holes 11 and 12 are arranged vertically in pairs and are fed from a central hole 13 common to all holes 11 and provided in the spindle guide 14 and from a separate oblique hole 15 through the spindle 14. be done. A spray pin 9 is fixed to the front end surface of the spindle guide 14.

As can be seen in FIG. 1, the above-mentioned bolts extending through holes 5 in the head 4 keep the front part 1 of the injection valve housing in sealing engagement with the inner surface of the cylinder cover 2, while the spindle guide 14 Against the shoulder of the valve housing, the elongated thrust bush 16, the flange of the inner sliding guide 17 and the spring guide 1 whose top engages with the threaded connection 6
8 and is fixed in the axial direction.

On the outside of the spindle guide 14 a conical valve seat is provided which cooperates with a mating conical seat at the lower end of the tubular valve member 19, which at its top and seat respectively has a thrust bush 16. It is guided and centered by the spindle guide 14. Inlet 8 to housing parts 3 and 4
A gas flow passage or duct 20 flowing through longitudinal and transverse holes is provided between the valve member 19 and the inside of the front part 1 of the injection valve housing forwardly to the valve seat at the end of the valve member 19. It is sectioned. In the closed position of the valve seat 19, its seat surface interrupts the connection from the duct 20 through the bore 15 to the nozzle bore 12. The valve member is held in the closed position by a helical spring 21 housed in a chamber 22 defined between the housing part 3 and the thrust housing 16, the top of which abuts a flange 23 at the upper end of the thrust bush 16. At the same time, the bottom of the spring abuts a corresponding flange 24 at the upper end of the valve member 19.

As shown in FIG. 2, the upper and lower ends of the chamber 22 are partitioned in a gas-tight manner, with suitable sealing rings inserted into the flanges 23 and 24 which abut against the empty walls.

Via the transverse holes 25, the chamber is also in open communication with the aforementioned system of holes connecting the gas population 8 with the duct 20. As a result, the same pressure prevails in the chamber 22 as in the gas inlet 8, which pressure acts on the flange 24 and thus also on the valve member 19 on the spindle guide 14 with a force exerted by the closing spring 21 and supplementing the force exerted by the closing spring 21. act in the direction toward the valve seat.

During the working cycle, the valve member 19 is lifted from its seat;
When gas injection into the combustion chamber 10 has to be started, servo oil is added to the lowers at a convenient high pressure, for example 500 bar, but the inlet lowers are connected to the second set of housing parts 3 and 4. It communicates via longitudinal and transverse holes with a small annular chamber 26 below the flange 24 of the valve member.

In the practical example shown, it is assumed that the servo oil is delivered from a Bosch type metering pump 3 and that in this connection a pressure limiting valve 27 is incorporated in the head 4 of the injection valve so that the pressure is The spring-loaded valve member of the pressure limiting valve 27 when the value necessary to lift the valve member 19 and keep it lifted until discharge from the pump is interrupted. 28 is adjusted to open, thereby relieving the pressure within the annular chamber 26. If instead of this the servo oil pressure in the chamber 26 was provided by a valve-controlled opening of the connection from an oil sump with the required pressure, the restriction valve would be unnecessary. This is because when the valve member 19 is lifted up to the maximum so as to come into contact with the thrust bush 16, the oil supply from the oil reservoir to the chamber 26 automatically stops.

The pilot oil, which must be injected into the combustion chamber 10 through the nozzle hole 11 in a known manner immediately before or at the same time as the start of the gas injection, is supplied from a Bosch type pump with a threaded connection, as mentioned by the introduction section. 6. The oil passes from there through aligned passages in the hollow spring guide 18 and relief slide 29;
Annular chamber 30 between slide 29 and central thrust tube 31
flows to The lower end of the thrust pipe 31 constitutes a guide for a valve member 32 of the pilot oil valve body, and the valve member 3
2 has a hole 13 in the bottom of the spindle guide 14.
A seat surface is provided which cooperates with the valve seat around the valve seat.

During the engine between supplies from the pilot oil pump, the relief slide 29 occupies the position shown, in which position it prevents oil from passing forward from the chamber 30 under the action of a relatively weak spring 34. Blocked. In the engine, oil flows forward from the oil pump to the injection valve inlet 6.
and through the transverse holes of the spring guide 18 to the rear to the suction side of the initial pump, which circulation can take place in a known manner, for example as described in EP-AI-0052937. and as the oil pressure increases,
The slide 29 moves up and the oil flows from the chamber 30 to the valve member 3.
When released for further passage into the corresponding annular chamber 35 in front of 2, said guide 18 is blocked by a slide 29. When the pressure in the annular chamber 35 overcomes the pressing force exerted by the closing spring 33, pilot oil flows into the hole 1.
3 and exits through the nozzle hole 11.

The inlet 36 of the head 4 is also shown in FIGS. 2 and 3;
The inlet 36 supplies a suitable sealing and lubricating oil through the holes in the head 4 and housing portion 32 at a convenient pressure.
It can be distributed to the inner and outer sliding surfaces of the valve member 19.

In FIG. 4, components that operatively correspond to those shown in FIGS. 1-3 are given the same reference numerals plus 100. The structural difference between the two embodiments is that the valve member 132 of the pilot oil valve in front of the conical seat is lengthened by a tubular slide 141 that fits relatively tightly into the atomizer 109. , in the illustrated position where the two conical seats abut each other, the tubular slide 141 is blocking the nozzle hole 111. The internal hollow space 142 of the slide communicates via a recess 144 in the side wall with an annular chamber 143 located downstream of the conical seat.

By adding a slide 141 that projects slightly forward past the nozzle hole 111 in the closed position, the valve member 132
Since the hole is closed during the closing movement when the chambers 143 and 135 are not yet completely closed, there is still communication between the chambers 143 and 135.
It is clear that there is communication further rearward from there toward the oil pump. The end of oil injection therefore occurs at a point in time when the oil pressure is relatively high, thereby reducing the risk of undesired dripping.

Moreover, the rearward flow of fuel during the subsequent last part of the closing movement relieves the abutment between the conical seats.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a first embodiment of the injection valve according to the present invention attached to a cylinder cover, taken along the line II in FIG. 3, and FIG. FIG. 3 is a plan view of the injector seen from above or from the outside; FIG. 4 is a front section of the second embodiment of the invention; FIG. It is an enlarged partial sectional view. 1.3.4...Housing, 8...Gas inlet, 10
... Combustion chamber, 11.12... Nozzle hole, 19...
Valve member, 21... Closing spring, 22... Chamber, 24...
·piston. Applicant's agent Sato-Yu 76J

Claims (1)

Claims: 1. A pressurized gas inlet (8) and one or more nozzle holes (12) at the front end of the injection valve facing this inlet and the combustion chamber (10) of the engine cylinder. an elongate housing (1, 3, 4) having a duct between the gas duct and the gas duct being controlled by a valve member (19) cooperating with a seat of the injection valve housing, the valve member being energized; In a fuel injection valve for a gas-powered diesel engine of the type adapted to act in the direction towards the seat by a closing spring (21) and in the opposite direction by a periodically applied servo oil pressure. , a chamber (22) in permanent communication with the gas duct is provided in the injection valve housing, the chamber being axially connected to a displaceable piston (24) in force transmission connection with the valve member (19). A fuel injection valve characterized by having a front section sealed in a sealed state. 2. The fuel injection valve according to claim 1, wherein the piston (24) is integral with the rear end of the valve member (19). 3. The closing spring (21) is connected to the fixed wall (23) of the housing.
3. The fuel injection valve according to claim 1, wherein the fuel injection valve is located in a chamber between the rear part of the piston (24) and the rear part of the piston (24). 4. The fuel injection valve according to claim 3, wherein the chamber (22) is formed in a portion (3) of the injection valve that projects outside the engine cylinder when the injection valve is installed.