KR20130069451A - Fuel pump for a large turbocharged two-stroke diesel engine - Google Patents

Abstract

PURPOSE: A fuel pump for a large size turbo charging two stroke diesel engine is provided to densely and efficiently supply a lubricating/sealing oil by a first gap limited by integrating a lubricant conduit within a main plunger. CONSTITUTION: A fuel pump for a large size turbo charging two stroke diesel engine comprises a housing(11), a main plunger(14), a pump chamber(19), more than at least one fuel ports(23,25), a second plunger(30), a second pump chamber(32), an injecting lubricant port(34), and a lubricant conduit(42). The main plunger goes and returns by a limited first gap within a main bore(15) of the housing. The pump chamber is limited by the bore and the main plunger. The fuel port is connected by a fluid with the pump chamber. The second plunger has a limited second gap, and slides down within a second bore. The second pump chamber is limited by the second bore and the second plunger. The injecting lubricant port is connected by a fluid with the second pump chamber. The lubricant conduit is arranged within the main plunger, and is connected to the second pump chamber, and is opened to the limited first gap.

Description

Fuel pump for a large turbocharged two-stroke diesel engine

The present invention relates to a fuel pump for a large turbocharged two-stroke diesel engine, and more particularly to a large turbocharged two-stroke diesel engine operating on alternative fuels that do not have good lubricating properties or on abrasive fuels. It relates to a fuel pump for.

Large turbocharged two-stroke diesel engines with crossheads are commonly used as prime movers for large external vessels or power plants, such as container ships.

Rising oil prices have led to attempts to operate large two-stroke diesel engines as alternative fuels such as DME (dimethyl ether), petroleum coke and coal slurries. Such fuels have good combustion properties to use, but differ significantly from traditional fuels such as fuel oil or heavy fuel oil in that they are substantially free of lubrication. The lack of lubrication creates some problems with high pressure fuel pumps that deliver high pressure fuel to fuel valves on top of the engine cylinders.

Conventional fuel pumps have a hydraulically actuated reciprocating plunger or cam located in the bore with a limited play between the plunger and the bore. Lubrication between the circumferential surface of the plunger and the inner surface of the bore is provided by applying fuel oil at a clearance defined by the pump pressure. This fuel oil in the play provides sufficient lubrication. However, this is not the case when various alternative fuels are used, and traditional fuel pumps that do not change because of the seizure or the like when the fuel pump has poor lubricating properties or even when operated with abrasive alternative fuels. Will fail.

Japanese Patent No. 1030679 discloses a diesel engine for dimethyl ether provided with a communication tube provided for communicating a cam chamber with a plunger lower chamber of a fuel injection pump. DMC (dimethyl ether) fuel gas that leaks and evaporates into the gap between the plunger and the plunger barrel, flows through the communication tube into the cam chamber, and the flow into the cam chamber through the tappet portion of the injection pump is reduced. Can be. The DME flowing in the cam chamber is sent from the intake pipe to the combustion chamber of the engine through the camshaft, engine crank chamber and blowby gas conduits for use as fuel. The height of the lubricating oil in the camshaft is pushed up by the gas flowing in the camshaft so that lubrication under the plunger can be sufficiently obtained.

SUMMARY OF THE INVENTION The present invention is directed to overcoming or at least reducing the disadvantages and problems presented above, and to provide an engine that operates on fuels that do not have good lubricating properties or that also operates on abrasive fuels.

The present invention provides a housing defining a main bore (15) for a large multi-cylinder two-stroke turbocharged diesel engine with a cross-head, seated to slide within the main bore with a defined first play and within the main bore. A pump chamber defined by the main plunger, the bore and the main plunger configured to reciprocate in at least one fuel port in fluid communication with the pump chamber, a second plunger seated to slide within the second bore with a defined second clearance, A second pump chamber defined by the second bore and the second plunger, a lubricating oil inlet port fluidly connected to the second pump chamber, a lubricating oil conduit connected to the second pump chamber and opened into the defined first play and arranged in the main plunger It is characterized by providing a fuel pump.

The invention also provides a plurality of cylinders, a cross-head, a lubricant supply system, an injection valve associated with the cylinder, a low pressure fuel supply system, a fuel pump having a housing defining a main bore 15, a main having a defined first clearance At least one fuel injection port that slides in the bore and is configured to reciprocate within the main bore, the pump chamber defined by the bore and the main plunger, the low pressure fuel supply system and in fluid communication with the pump chamber A second pump chamber, a second pump chamber defined by a second plunger, a second bore and a second plunger, which are slidably seated in the second bore with a defined second clearance; Lubricant injection port in fluid communication with the second pump chamber, open into the defined first clearance and arranged on the main plunger To provide a large two-stroke slow danryu Turbocharged diesel engine comprising a lubricating oil duct is characterized.

In one embodiment of the invention the second plunger is the reduced diameter range of the main plunger and the second bore is the reduced diameter range of the main bore. Thus, two plungers occupy a small space and are easy to produce in one process from one material.

In one embodiment of the invention the second plunger operates in accordance with the main plunger. Therefore, the fuel pump is simple and reliable and the lubrication supply is automatically matched with the fuel injection timing.

In one embodiment of the invention one end of the lubricant conduit is directly connected with the second pump chamber.

In one embodiment of the invention the second bore is formed in the main plunger and the second plunger is fixed to the housing and protrudes through the pump chamber into the second bore. Therefore, the fuel pump is made simple and reliable and the lubrication supply is automatically matched with the fuel injection timing.

In one embodiment of the invention, the lubricant supply channel connects the second pump chamber with the lubricant injection conduit and the lubricant supply channel is formed in the second plunger and the pump housing.

In one embodiment of the invention the diameter of the second plunger, the defined first play and the defined second play are designed such that the lubrication / sealing oil is pushed into the pump chamber from the defined first play and the defined second play during the pump stroke. Thus, the fuel is prevented from entering the defined first or second play and the lubrication / sealing oil is ensured to be within the defined first and second play for lubrication of the main plunger and the second plunger.

The present invention can provide a dense and efficient lubrication / sealing oil supply with a limited first clearance by integrating the lubrication conduit into the main plunger, which has the effect of well lubricating the main piston and preventing fuel from entering the main clearance. have.

In the following detailed description of the invention, the fuel pump will be described in more detail by reference to the exemplary embodiments and figures shown in the drawings.
1 is a cross-sectional view of a fuel pump according to an exemplary embodiment of the present invention.
2 is a cross-sectional view of a fuel pump according to another exemplary embodiment of the present invention.

Further objects, features, advantages and characteristics of the fuel pump and the large two-stroke diesel engine according to the present disclosure will become apparent from the detailed description.

In the detailed description below, a fuel pump 10 for a large two-stroke engine will be disclosed by way of example embodiments. 1 and 2 show some other parts of a fuel pump and a fuel system of a large low speed turbocharged slow running two-stroke diesel engine in accordance with an exemplary embodiment.

The fuel system includes one or more fuel tanks. Dedicated fuel tanks for specific fuels may be provided. Such a fuel tank may be a heating fuel tank for heavy oil, or a coal slurry tank having stirring means and a coal and water mixing unit or a petroleum coke tank having stirring means and a petroleum coke and water mixing unit.

The fuel system of a large two-stroke diesel engine includes a plurality of fuel pumps for sending high pressure fuel to a fuel valve at the top of the engine cylinder. In general, one fuel pump is provided for each cylinder. Fuel such as heavy oil, coal slurry or petroleum coke is supplied to the fuel pump 10 by a low pressure pump. The fuel tank, supply system and low pressure pump are represented by source symbols 12 at FIGS. 1 and 2.

The main plunger 14 with the pump cylinder is slidably received in the main bore 15 in the cylinder housing or pump barrel 16 such that the main plunger 14 and the main bore 15 have a limited first clearance. do. The main plunger 14 is moved in the conveying direction by a camshaft driven by the engine and is moved backward by the plunger spring, or the main plunger 14 is moved in the conveying direction by hydraulic pressure and the plunger spring And / or back by fuel pressure. The cam or hydraulic pressure is indicated by arrow 17 in FIG. 1. Hydraulic pressure is controlled by a proportional valve (not shown). The proportional valve is controlled by an electronic control unit. The electro-hydraulic control of the proportional valves enables the determination of fuel injection rate and variable injection timing.

Cam-driven pumps can be used in engines capable of rotating in reverse. The injection timing in the reverse rotation can be improved by changing the roller position relative to the cam. Cam driven pumps are variable injection timing (VIT) pumps.

At the longitudinal end of the main plunger opposite the main pressure chamber 19 there is a protector 13 which directs the leak oil into the outlet oil collection channel and this end of the main plunger is actuating plunger 16. Is in contact with the first end. The cam or hydraulic pressure 17 actuates the other end of the actuating plunger 16.

When the fuel pump is a cam drive, the stroke distance of the main plunger 14 is fixed, and the main plunger 14 performs a suction stroke and a compression stroke through a full stroke for each rotation of the cam shaft. However, in the cam driven fuel pump 10, an efficient stroke, for example a displacement suitable for the pump stroke, uses a squint cut-off edge in combination with the adjustable rotational position of the main plunger. You can change it in a well known way.

The pump chamber 19 is defined by a pump housing 11 between the top of the main plunger 14 and the inner wall of one end of the main bore 15.

The pump chamber 19 is connected to the fuel injection port 23 and the fuel discharge port 25 through the conduit 21.

The fuel injection port 23 is connected to the fuel supply system 12 through the fuel supply conduit 27. The discharge port 25 is connected to a fuel valve (not shown) of the engine cylinder (not shown). A non-return valve 28 of the fuel supply conduit 27 prevents fuel from flowing back into the fuel supply system 12.

During the intake stroke, the main plunger 14 sucks fuel into the pump chamber 19 through the fuel injection port 23.

During the pump stroke, when the pressure in the pump chamber 19 rises and exceeds the threshold, the fuel valve opens and fuel is transported from the pump chamber 19 to the discharge port 25.

The second plunger 30 extends from the main plunger 14. Although it is understood that the second plunger 30 and the main plunger 14 may consist of two connected parts, in this embodiment the second plunger 30 is concentric with the main plunger 14 and integral with it. to be. The second plunger 30 extends through the main pump chamber 19 from the main plunger 14 into a second bore formed in the pump housing 11. The second bore is the concentric extension of the main bore 15. The second plunger 30 has a limited second play and is slidably accommodated with the second bore. The second pump chamber 32 is defined by the second bore and the second plunger 30. The second pump chamber is connected to the lubricating oil injection port 34. The low pressure lubricating oil pump 36 supplies the lubricating oil or the sealing oil from the lubricating oil and the sealing oil storage part 38 to the lubricating oil injection port 34 through the lubricating oil or the sealing oil supply line 40.

Lube conduit 42 is arranged in main plunger 14. One end of the lubricant conduit 42 is connected to the second pump chamber 19 and the other end of the lubricant conduit 42 opens into the first play. Lube conduit 42 may be branched to have a plurality of ends that open into a defined first play at several locations circumferentially and axially apart.

The movement of the second plunger 30 coincides with the main plunger 14. The second pump chamber 19 is also pressurized during the pump stroke. The action of the mass flow of the lubrication / sealing oil again depends on the pressure in the second pump chamber 19 which again depends on the defined first clearance between the main plunger and the main bore and the defined second clearance between the second plunger 30 and the second bore. to be.

The reciprocating movement of the second plunger 14 creates a pressure of a size determined by the size of the diameter of the second plunger 30 and the size of the defined first play and the size of the defined second play, the sealing / lubricating oil being the play This leads to the main pump chamber which eventually mixes with the fuel or reaches the drain oil channel.

The diameters of the first clearance, the second clearance and the second plunger 30 are mutually different such that the actual pressure of the sealing / lubricating oil flowing from each clearance to the main pump chamber 19 is higher than the actual pressure in the main pump chamber 19. Is designed for.

The fuel injection pressure for large two-stroke diesel engines is currently around 800 bar and is expected to be higher in the future. The pressure of the sealing / lubricating oil at the first and second play during the pump stroke should be at least 50 bar higher than the pressure at the pump stroke.

Thus, in order to ensure that the pressure of the sealing / lubricating oil at defined play during the pump stroke is higher than the fuel pressure in the pump chamber, the highest pressure of the second pump chamber 32 is approximately higher than the highest pressure of the main pump chamber. It is required to be 100 bar and as a result it is ensured that the sealing / lubricating oil flows from the limited play at the controlled rate to the main pump chamber and that the fuel does not reach within the defined play.

Since the second plunger 30 and the main plunger 14 move in unison, the sealing oil or lubricant supply is aligned with the fuel injection and prevents fuel from entering the two limited clearances between the plunger and the bore, thereby preventing the seizure. prevent.

The lubricating oil pump 36 must supply the seal / lubricating oil at a pressure at least slightly higher than the supply pressure of the fuel to prevent the fuel from entering the defined play at low pressure cycles.

2 shows another exemplary embodiment of a fuel pump. This embodiment shows that the second plunger 30 is fixed to the pump housing 11 and penetrates through the main pump chamber 19 to protrude into a second bore formed at one end of the main plunger 30. It is basically the same as the embodiment according to 1. Thus, the second pump chamber 32 is bounded by the second plunger 30 and the second bore and has a second clearance defined between the second plunger 30 and the second bore in the main plunger 14. Is formed. A lubrication / sealing oil supply conduit 33 connecting the lubrication / sealing oil injection port 34 to the second pump chamber 32 is formed in the pump housing 11 and the second plunger 30.

When the main plunger 14 is forced by the hydraulic actuator or cam 17 to make a pump stroke, the second plunger is forced into the second bore and thus lubrication / silication, as in the exemplary embodiment according to FIG. 1. The transfer of oil will automatically coincide with the timing of fuel injection. Defining the value of the defined second play and the diameter of the second piston are also the same as the embodiment according to FIG. 1.

The second plunger 30 has an embodiment such as the cylindrical shape described above. However, it should be understood that the second plunger may have an oval, hollow cross-sectional ring or other suitable cross-sectional shape. In addition, it may be two smaller second pistons instead of one larger second piston.

The term lubricating oil or sealing oil is to be interpreted broadly and includes any liquid having suitable lubricating properties, for example heavy oil, fuel oil (diesel) or dedicated lubricant.

The term "comprising" as used in the claims does not exclude other components or steps. The term "one" as used in the claims does not exclude a plurality. One processor or other unit may perform the functions of several means listed in the claims.

Reference signs used in the claims should not be construed as limiting the scope of the invention.

Although the present invention has been described in detail for purposes of illustration, such detailed description is for that purpose only, and variations may be made by those skilled in the art without departing from the scope of the invention herein.

10: fuel pump 11: pump housing
12: fuel supply system 13: protector
14: main plunger 15: main bore
16: motion plunger 17: cam
19: pump chamber 21: conduit
23: fuel injection port 25: discharge port
27: fuel supply conduit 28: check valve
30: second plunger 32: second pump chamber
33: Lubrication / sealing oil supply conduit 34: Lubrication oil injection port
36: Lube oil pump 38: Lube and sealing oil reservoir
40: lubricant and sealing oil supply line

Claims (8)

In a fuel pump for a large multi-cylinder two-stroke turbocharged diesel engine having a cross-head, the fuel pump comprises:
A housing 11 defining a main bore 15,
A main plunger 14 slidably received in the main bore 15 with a limited first play and configured to reciprocate within the main bore 15,
A pump chamber 19 defined by the bore 15 and the main plunger 14,
At least one fuel port (23, 25) in fluid communication with the pump chamber (19),
A second plunger 30 seated to slide within the second bore with a defined second play,
A second pump chamber 32 defined by the second bore and the second plunger 30,
Lubricating oil inlet port 34 in fluid communication with the second pump chamber 32,
Lubricating oil conduit (42) disposed in the main plunger (14) and connected to the second pump chamber (32) and open to the limited first clearance.
A fuel pump comprising a. The method of claim 1,
The fuel pump, characterized in that the second plunger (30) is in the reduced diameter range of the main plunger (14) and the second bore is in the reduced diameter range of the main bore (15). The method of claim 2,
The fuel pump, characterized in that the second plunger (30) operates in accordance with the main plunger (14). The method of claim 2,
A fuel pump, characterized in that the end of the lubricating oil conduit (42) is directly connected to the second pump chamber (32). The method of claim 1,
And the second bore is formed in the main plunger (14) and the second plunger is fixed to the housing (11) and protrudes into the second bore through the pump chamber (19). 6. The method of claim 5,
A fuel pump comprising a lubricating oil supply channel (33) formed in the second plunger (30) and the pump housing (11) and connecting the second pump chamber (32) and the lubricating oil injection port (34). . The method of claim 1,
The diameter of the second plunger 30 is defined by the first play and the defined play so that the lubrication / sealing oil is driven into the pump chamber 19 from the defined first play and the defined second play during pump reciprocation. A fuel pump, characterized in that the second play is dimensioned. A fuel pump having a plurality of cylinders, a cross-head, a lubricant supply system, an injection valve associated with the cylinder, a low pressure fuel supply system, a housing 11 defining a main bore 15, a main bore 15 with a defined first clearance Pump chamber 19, which is slidably accommodated by the main plunger 14, configured to reciprocate in the main bore 15, the bore 15 and the main plunger 14, At least one fuel injection port 23 in fluid communication with the pump chamber 19, a fuel discharge port 25 in connection with at least one fuel valve, and a second bore with a defined second clearance A lubricating oil fluidly connected to the second pump chamber 32 and the second pump chamber 32 defined by the second plunger 30, the second bore and the second plunger 30 slidably received in the second plunger 30. Injection port 34, said A lubricant conduit 42 disposed in the main plunger 14 and connected to the second pump chamber 32 and open to the defined first play:
Large slow two-stroke turbocharged single flow diesel engine comprising a.

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