JPH0452860B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a pressurized gas inlet and one or more of the front ends of the injector facing the combustion chamber of an engine cylinder. an elongate housing having a duct between the nozzle bore and the gas duct, the gas duct being controlled by a valve member cooperating with a seat of the injection valve housing, the valve member being biased in the direction towards the seat by a biased closing spring. and relates to a gas-powered diesel engine fuel injector of the type adapted to be counteracted by periodically applied servo oil pressure.

[Conventional technology and its problems]

Diesel engines that use gas as fuel are
Among other things, they are of interest as propulsion engines for gas tankers, particularly for transporting liquid natural gas (LNG), where the amount of gas that inevitably evaporates from the cargo is utilized with a high degree of efficiency in diesel engines. 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 stuck in the fully or partially open position, and
This is the case if considerably more gas is injected during the working cycle than corresponds to the amount of oxygen contained in the cylinder. Later, the amount of unburned gas flowing from the cylinder that is mixed with the hot combustion gases naturally occurs somewhere in the exhaust system where it comes into contact with the free oxygen present in the exhaust gas 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 and in force-transmitting connection with the valve member. The front part is sealed and partitioned by a piston.

[Effect]

What this results in under normal operation of the engine is that the valve member, due to two co-operating forces,
i.e. partly by means of a closing spring and partly in a supply system connected to the gas inlet of the injection valve.
Therefore, also due to the relatively high pressure continuously prevailing in the gas duct of the injection valve, often approx.
It is instantaneously applied in the closing direction by a pressure of 200 bar. The closing spring can therefore be dimensioned according to a relatively low pressing force and/or a relatively low internal stress, resulting in smaller spring dimensions and/or a highly variable influence exerted on the valve spring. The safety against fatigue failure caused by 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, suitable precautionary measures for closing the check valve and thereby interrupting the supply of gas to one or more injection valves of the cylinder in case of abnormally high gas flows. As a supplementary note, the precautionary measure, on the other hand, does not prevent at least a portion of the gas quantity downstream of the closed check valve from leaking into the engine cylinder.

In a simpler 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 in line 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 a cylinder cover 2 of the engine, a central part 3 with a slightly larger diameter, and an injection valve that is housed in the cylinder cover. It includes an elongated housing having a head 4 having a continuous bore 5 (see FIG. 3) for receiving a fastening bolt.
A threaded connection 6 fixed in the center of the head 4 is connected to a high pressure source such as a conventional fuel pump of the bottle type for periodically discharging a defined quantity of luminous pilot oil to the injection valve. It is now connected to the duct.

A control or servo oil inlet 7 for opening the gas valve in the injection valve, which will be described later, is connected to the head 4.
is formed with a corresponding inlet 8, which inlet 8 is normally continuously open for supplying high pressure gas from a suitable source for injection into the engine cylinder when the gas valve of the injector is open. It is connected to the conduit that is connected to the

A sprayer 9, which projects from the front end of the housing 1 into the combustion chamber 10 of the engine cylinder, has two sets of nozzle holes 11 and 12 for injecting pilot oil and gas, respectively. Nozzle holes 11 and 1
2 are placed vertically in pairs and are common to all holes 11 and fed from a central hole 13 provided in the spindle guide 14 and from a separate oblique hole 15 through the spindle 14. A sprayer 9 is fixed to the front end face of the spindle guide 14.
As can be seen in FIG. 1, the aforementioned 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 Attach the elongated thrust bush 1 to the shoulder of the valve housing.
6. The flange and top of the inner sliding guide 17 are axially fixed via a spring guide 18 which engages with the screw connection 6.

On the outside of the spindle guide 14 there is a tubular valve member 1
A conical valve seat is provided which cooperates with a mating conical seat at the lower end of 9, the tubular valve member 19 being guided and centered at the top and seat respectively in the thrust bush 16 and in the spindle guide 14. has been done. A gas flow passage or duct 20 flowing from the inlet 8 through longitudinal and transverse holes in the housing parts 3 and 4 is provided between the valve member 19 and the inside of the front part 1 of the injection valve housing. It is divided forward to the valve seat at the end. In the closed position of the valve seat 19, its seating surface blocks the connection from the duct 20 further 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 piston 24 at the upper end of the valve member 19.

As shown in FIG. 2, the upper and lower ends of chamber 22 are gas-tightly partitioned, and suitable sealing rings are inserted into flanges 23 and 24 which abut against the walls of the chamber.
Via the transverse holes 25, the chamber is also in open communication with the aforementioned system of holes connecting the gas inlet 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 piston 24 and thus also on the valve member 19 on the spindle guide 14 with a force complementary to the force exerted by the closing spring 21. act in the direction toward the valve seat.

During the working cycle, when the valve member 19 has to be lifted from its seat and the gas injection into the combustion chamber 10 has to begin, servo oil is applied to the inlet 7 at a conveniently high pressure, for example 500 bar;
The inlet 7 communicates via a second set of longitudinal and transverse holes in the housing parts 3 and 4 with a small annular chamber 26 below the flange 24 of the valve member. In the actual embodiment shown, it is assumed that the servo oil is delivered from a dosing pump of the bottle type, and in this connection a pressure control valve 27 is integrated in the head 4 of the injection valve, so that the pressure is the spring-loaded valve of the pressure control valve 27 when the value necessary to lift the valve member 19 and keep it lifted until delivery from the metering pump is interrupted; Member 28 is adjusted to open, thereby relieving the pressure within 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.

Immediately before the start of gas injection or simultaneously with the start of gas injection, the combustion chamber 1 is
The pilot oil that has to be injected into the threaded connection 6 can be supplied from a bottle-type dosing pump to the threaded connection 6, as described from the inlet.
The oil flows from there through aligned passages in the hollow spring guide 18 and the relief slide 29 into an annular chamber 30 between the slide 29 and the central thrust tube 31. The lower end of the thrust tube 31 constitutes a guide for a valve member 32 of the pilot oil valve body, the front part of said valve member 32 cooperating with a valve seat around the hole 13 in the bottom of the spindle guide 14. A seat is provided.

During the engine between supplies from the pilot oil pump, the relief slide 29 occupies the position shown, in which the relief slide 29 prevents oil from passing forward from the chamber 30 under the action of a relatively weak spring 34. Blocked. In said engine, oil is continuously circulated from the oil pump forward to the injection valve inlet 6 and rearward through the transverse bore of the spring guide 18 to the suction side of the initial pump, this circulation occurring in a known manner. This can be done, for example, as described in EP-A1-0052937, when the oil pressure increases, the slide 29 rises and the oil flows into the chamber 30.
Said guide 18 is blocked by the slide 29 when released for further passage from the valve member 32 into the corresponding annular chamber 35 in front of the valve member 32 . When the pressure in the annular chamber 35 overcomes the pressing force exerted by the closing spring 33, the pilot oil flows into the bore 13 and out through the nozzle bore 11.

An inlet 36 of the head 4 is also shown in FIGS. 2 and 3 through which a suitable sealing and lubricating oil may be supplied at a convenient pressure through holes in the head 4 and housing portion 32. It can be distributed to the inner and outer sliding surfaces of the 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 bore 111 in the closed position, said bore is blocked during the closing movement at a time when the valve member 132 is not yet completely closed, so that chambers 143 and 135 are still closed. It will be clear that there is communication between the oil pumps and thence further rearwardly towards 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 shows a first embodiment of an injection valve according to the present invention mounted on a cylinder cover along the line -
2 is an enlarged partial sectional view of the top or rear part of the injector taken along the line - of FIG. 3; FIG. 3 is an injector viewed from above or from the outside. FIG. 4 is a plan view of the second embodiment of the present invention.
FIG. 3 is an enlarged partial cross-sectional view of the front portion of the embodiment. 1, 3, 4...Housing, 8...Gas inlet, 10
...Combustion chamber, 11, 12... Nozzle hole, 19... Valve member, 21... Closing spring, 22... Chamber, 24... Piston.

Claims (1)

Claims: 1. A pressurized gas inlet 8 and a duct between this inlet and one or more nozzle holes 12 at the front end of the injection valve facing the combustion chamber 10 of the engine cylinder. comprising an elongated housing 1, 3, 4 having an elongated housing 1, 3, 4, said gas duct being controlled by a valve member 19 cooperating with a seat of the injection valve housing, said valve member being actuated in the direction towards the seat by a biased closing spring 21; , and in fuel injection valves for gas-powered diesel engines of the type adapted to be actuated periodically in the direction away from the seat by periodically applied servo oil pressure, permanently connected to the gas duct. It is noted that a communicating chamber 22 is provided in the injection valve housing, which chamber is axially and sealingly partitioned at the front by a displaceable piston 24 which is force-transmittingly connected to the valve member 19. Characteristic fuel injection valve. 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. Fuel injection valve according to claim 1 or 2, in which the closing spring 21 is located in a chamber between the fixed wall 23 of the housing and the rear part of the piston 24. 4. The fuel injection valve according to claim 3, wherein the chamber 22 is formed in the portion 3 of the injection valve that projects outside the engine cylinder when the injection valve is installed.