DK177456B1

DK177456B1 - A fuel valve for large turbocharged two stroke diesel engines

Info

Publication number: DK177456B1
Application number: DKPA201100479A
Authority: DK
Inventors: Johannes Flarup; Mikkel Thramsborg
Original assignee: Man Diesel & Turbo Deutschland
Priority date: 2011-06-27
Filing date: 2011-06-27
Publication date: 2013-06-17
Also published as: KR101407811B1; EP3406891A1; CN102852686B; PL2541037T3; EP3406891B1; EP2541037B1; JP2013011274A; PL3406891T3; KR20130001685A; CN102852686A; EP2541037A2; DK201100479A; JP5526194B2; EP2541037A3

Abstract

A fuel valve (1) for injecting fuel into the combustion chamber of a large turbocharged two stroke diesel engine, with a resiliently biased and axially movable valve needle (20) cooperating with a valve seat (22), a plurality of nozzle holes (35) distributed axially and radially over the nozzle (30), an electronically controlled valve connected to a closing chamber in for urging the valve spindle (20) to its seat (22) for alternatively connecting the closing chamber to a tank port (18) or to a fuel inlet port (16)

Description

i DK 177456 B1

A FUEL VALVE FOR LARGE TURBOCHARGED TWO STROKE DIESEL ENGINES

The present invention relates to a fuel valve for large 5 turbocharged two-stoke diesel engines, in particular to en electronically controlled fuel valve for the large turbocharged inflow two stroke diesel engines with cross heads .

10 BACKGROUND OF THE INVENTION

Large turbocharged two-stroke diesel engines with crossheads are typically used as prime movers in large ocean going ships, such as container ships or in power plants.

15

These engines are typically provided with two or three fuel valves arranged in each cylinder cover. The fuel valve is provided with a spring biased axially movable valve needle that acts as a movable valve member. When 20 the pressure of the fuel (typically heavy fuel oil) exceeds a preset pressure (typically 350 Bar) the axially movable valve needle is lifted from its seat and the fuel is allowed to flow into the combustion chamber via a nozzle at the front of the fuel valve.

25 A conventional nozzle has a longitudinal axis that is arranged roughly at an angle of 10 to 15 deg to the direction of the movement of the piston in the cylinder of the engine and the nozzle is provided with a central 30 bore and a plurality of nozzle bores that direct the fuel away from the cylinder walls and into the combustion chamber. Typically, there is a swirl in the air in the combustion chamber at the moment of injection, provided by the charge air inflow. Most of the nozzle bores are 2 DK 177456 B1 directed to inject the fuel with the flow of the swirl although some of the bores may be directed to inject the fuel against the flow of the swirl.

5 A known fuel valve of this type is the MAN Diesel slide fuel valve that has a design with a minimized sac volume of residual fuel. This known fuel valve has two positions: open with all nozzle holes in use or closed.

The position of the axially movable valve needle is 10 controlled by a pressure chamber in the valve housing above the axially movable valve needle. The pressure chamber is permanently connected to a high pressure fluid source via a throttled connection, and to a drain via a closable throttled connection. This construction causes 15 substantial drain loses during valve open time and causes relatively slow closing and opening speeds of the fuel valve. The high pressure fluid for controlling the needle valve is the fuel oil.

20 Ongoing demands for reduced emissions and improved specific fuel consumption require further development of the fuel injection system. Improved accuracy and faster opening and closing movement are key aspects.

25 In a conventional fuel valve for a large two stroke uniflow diesel engine with cross-heads the opening and closing of the valve needle of the fuel valve is controlled via a pressure chamber arranged in the fuel valve housing at an end of the valve needle that is 30 opposite to the nozzle. The valve needle is slidably and sealingly received in a bore in the fuel valve housing with the pressure chamber forming the end of the bore.

The pressure in the pressure chamber is controlled by a throttled connection to the high pressure fluid inlet 3 DK 177456 B1 port and another throttled connection to the tank port.

The connection to the tank port can be opened and closed by an electrically controlled solenoid valve that typically is a solenoid controlled ball valve. The 5 throttled connection to tank is less restricted than the throttled connection to the fuel port, and therefore pressure drops in the pressure chamber when the solenoid valve opens the connection to the tank port.

10 When the solenoid valve is closed the pressure in the pressure chamber increases until it reaches the pressure in the fuel inlet port. The speed with which the pressure in the pressure chamber increases is determined by the pressure difference between the pressure chamber and the 15 fuel inlet port and the size of the restriction in the connection between the two.

When the solenoid valve is open, the pressure in the pressure chamber falls until a balance determined by the 20 ratio between the size of the restriction in the connection to the tank port and the size of the restriction in the connection to the fuel port. The speed with which the pressure in the pressure chamber decreases is determined by this balance between the size of the two 25 restrictions.

Thus, the speed with which the valve needle opens and closes is determined by the restrictions, and both the opening and closing movement of the valve needle is 30 inherently slower than desired

The solenoid valve is open during a fuel injection event.

The flow through the restricted connections when the solenoids valve is open represents a large leak flow and 4 DK 177456 B1 the energy loss associated with this leak flow is quite substantial since the pressure at the fuel inlet is very high, typically 300 bar or higher.

5 DE102005060552 discloses a fuel injection system, for an internal combustion and especially diesel motor, that has a 2/2 way valve upstream of a pressure-controlled injection valve for fuel held in a pressure storage. A 3/2 way valve is upstream of the 2/2 valve, to provide a 10 flow path between the pressure storage and the 2/2 valve in one setting with another setting to connect the 2/2 valve to a lower pressure line. The injection valve has a needle held in the closed position by at least one spring. In DE102005060552 a pressure chamber 3 that acts 15 on a piston with a piston rod and the piston rod acts on the valve needle. In DE102005060552 the opening chamber is connected to the source of pressure via the same valve that is supposed to be the pilot valve, i.e. the opening chamber is only pressurized when the fuel injection takes 20 place. In DE102005060552 the fuel is allowed to flow all the way to the nozzle, also when the valve needle is not lifted. In DE102005060552, the pressure chamber is connected to the control valve via a restriction and the conduit connecting the two has a branch that connects to 25 the lower pressure chamber of the fuel valve.

The present demand for lower emissions and improved specific fuel oil consumption require faster reacting fuel valves and reduced energy losses through leak oil 30

DISCLOSURE OF THE INVENTION

On this background, it is an object of the present invention to provide a fuel valve that is able to at DK 177456 B1 5 least partially meet the demands indicated above and at least partially overcome the problems indicated above.

The present invention defines a fuel valve for injecting 5 fuel into the combustion chamber of a large two stroke diesel engine, with a resiliently biased and axially movable valve needle cooperating with a valve seat, an electronically controlled pilot valve connected to a closing chamber for urging the needle valve to its seat 10 for selectively, e.g. alternatingly, connecting the closing chamber to a tank port or to a fuel inlet port.

The object above is achieved by providing an electronically controlled fuel valve for injecting fuel ,15 into the combustion chamber of a large two stroke diesel engine with cross-heads, the fuel valve comprising a fuel valve housing, an elongated nozzle, a fuel inlet port for connection to a source of high pressure fuel, a conduit connecting the high pressure fuel inlet port to the 20 nozzle, a resiliently biased and axially movable valve needle cooperating with a valve seat and configured to control the flow of fuel from the fuel inlet port to the nozzle, whereby lift of the axially movable valve needle allows flow from the fuel inlet port to the nozzle, a 25 closing chamber in the valve housing acting on the valve needle with a first effective surface area and urging the valve needle towards the valve seat when the closing chamber is pressurized, an opening chamber in the valve housing said opening chamber being in fluid connection 30 with said first duct to be pressurized by said source (P), pressure in said opening chamber (70), said opening chamber acting on the valve needle with a second effective surface area and urging the valve needle away from the valve seat, a control conduit directly 6 DK 177456 B1 connecting the closing chamber to a valve port of an electronically controlled pilot valve, the electronically controlled pilot valve being provided with a valve port connected to the tank port and with a valve port 5 connected to the fuel inlet port, the electronically controlled valve being configured to selectively connect the control conduit to the tank port or to the fuel inlet port for electronically controlling lift of the valve spindle.

10

By using an electronically controlled pilot valve for controlling the pressure in the pressure chamber that urges the valve needle towards the seat, i.e. the closing chamber, by selectively connecting the control conduit to 15 the tank port or to the fuel inlet port it becomes possible to reduce the leak oil flow significantly. The needle valve opening and closing can be electronically controlled and, the valve needle can be opened faster and closed faster which results in better control of the fuel 20 injection. These measures are resulting in lower specific fuel of consumption and allow for emission reduction.

Preferably, the electronically controlled valve is a spool valve.

25

In an embodiment in the spool valve is provided with a first pressure chamber acting on the spool and urging the spool to a position where the control conduit is connected to the fuel inlet port.

30

The spool valve may also be provided with a second pressure chamber acting on the spool and urging the spool to a position where the control conduit is connected to the tank port.

7 DK 177456 B1

In another embodiment the pressure chamber is provided with a throttled connection to the fuel inlet port and with another throttled connection to the tank port, with 5 the throttled connection to the tank port is less restricted than the throttled connection to the fuel inlet port and wherein the fuel valve (1) further comprises an electrically controlled solenoid valve for opening and closing the throttled connection to the tank 10 port.

Preferably, the solenoid valve is a solenoid controlled ball valve. This construction allows for the use of an off-the shelf type solenoid valve to control the position 15 of the spool.

In an embodiment the restricted connection to the tank port is located inside the valve housing.

20 In an embodiment the restricted connection to the tank port is located extends through the spool of the spool valve.

In an embodiment the nozzle is a nozzle with an axial 25 bore and a closed front and the valve needle moves in unison with a cut-off shaft moving in unison with the valve needle and received axially displaceable in the central bore in the nozzle for opening and closing the nozzle holes.

Further objects, features, advantages and properties of the fuel valve according to the present disclosure will become apparent from the detailed description.

30 8 DK 177456 B1

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present description, the invention will be explained in more 5 detail with reference to the exemplary embodiments shown in the drawings, in which:

Fig. 1 is a longitudinal-section of an exemplary embodiment of a fuel valve, and 10 Fig. 2 is a longitudinal-section of another exemplary embodiment of a fuel valve.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

15 The fuel valve 1 according to an exemplary embodiment illustrated in Fig. 1 has an external housing 10 which at its rearmost end has a fuel inlet port 16 and a fuel outlet port or tank port 18. The inlet port 16 is to be connected to a source P of high pressure fuel such as 20 fuel oil, heavy fuel oil from a fuel pump or from a common fuel rail. The outlet port 18 is to be connected to a return line to tank T.

The fuel valve 1 may in a known manner be mounted in the 25 cylinder cover of a large two-stroke turbocharged uniflow diesel engine with cross-heads and be connected with a fuel pump, not shown.

The fuel inlet port 16 is in flow connection with a duct 30 17. Duct 17 extends to the seat of a valve needle 20 that is axially displaceable in an axial bore in the valve housing 10. The valve needle 20 is biased to its seat 22 by a closing spring 23. The foremost part of the valve housing 10 holds a nozzle 30 that projects from the valve 9 DK 177456 B1 housing 10 and into the combustion chamber of the engine cylinder (not shown) when the fuel valve 1 is mounted on the cylinder cover.

5 Fig. 1 shows the valve needle 20 resting on the valve seat 22. In this position, fluid flow of fuel from the fuel oil inlet port 16 to the nozzle 30 is blocked. A chamber 25 above the valve seat 22 is connected to duct 17 to receive pressurized fuel.

10

The valve needle 20 carries a foremost cut-off shaft 40 that is thinner than the rearmost section of the valve needle 20 and the cut-off shaft 40 projects into a central bore 33 in the nozzle 30. Thus, when the valve 15 needle 20 is axially displaced in the bore in the housing 10 the cut-off shaft 40 is axially displaced in the central bore of the nozzle 30.

The nozzle 30 is further provided with a plurality of 20 nozzle holes 35 through which the fuel is injected into the combustion chamber from the central bore 33. Thus, during a fuel injection event a jet of fuel comes from the nozzle holes 35.

25 The cut-off shaft 40 is in an exemplary embodiment made as one piece of material with the valve needle 20. The cut-off shaft 40 is hollow and the hollow interior of the cut-off shaft 40 connects to the space downstream of the valve seat 22. Thus, when the valve needle 20 is lifted 30 from its seat the flow path extends all the way from the fuel oil inlet 16 to the hollow interior of the cut-off shaft 40.

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DK 177456 E

10 A duct 19 is connected to the outlet port 18 and the duct 19 collects the return oil flow as will de explained in greater detail hereafter.

5 The foremost part of the cut-off shaft 40 is cylindrical and fits exactly into the central bore 33.

The upper (upper as in the drawings) part of the valve is a substantially cylindrical section 43 with an enlarged 10 diameter and this section 43 that is slidably received in an axial bore 45 in the valve housing 10 so that the section 43 can act like a piston in the valve housing 10.

A closing chamber 46 formed in the upper part (upper as in the drawing) of the valve housing 10 is disposed above 15 the actuation section 43. The spring 23 for urging the valve needle 20 onto its seat 22 is received in the closing chamber 46, and acts on the top of the actuation section 43. The pressure in closing chamber 46 acts on the valve needle 20 to urge the latter in the closing 20 direction with an effective surface area Al.

An opening chamber 70 for urging the valve needle 20 in the opening direction is located under section 43 and connected via bore 72 to duct 17. Opening chamber 70 is 25 therefore always pressurized when the fuel inlet port 16 is connected to a source of pressurized fuel (such as a fuel pump) . The pressure in opening chamber 70 acts on the valve needle 20 to urge the latter in the opening direction with an effective surface area A2.

30 A bore 52 is formed in the valve housing. In figure 1 the bore is oriented axially. However, other orientations for bore 52, such are radially or tangentially or orientations there in-between are also possible. A spool 11 DK 177456 B1 or slide 53 is slidably received in the axial bore 52 and the position of the spool 53 determines the flow to- and from three ports that open into the axial bore 52.

5 One of the ports connects via a conduit 57 to duct 17 that is connected the source of pressurized fuel via fuel inlet port 16. Another port is connected to duct 19 by a conduit 58 and the third port is connected to closing chamber 46 via a control conduit 59.

10 A reduced diameter section 55 of the spool 53 connects the control conduit 59 with conduit 57 in the lower (lower as in the drawing) position of the spool 53 and connects the control conduit 59 to conduit 58 in the 15 upper (upper as in the drawing) position (shown in Figure 1) of the spool 53. In the upper position of the spool 53 closing chamber 4 6 is connected to the outlet port or tank port 18 (drain) and in the lower position of the spool 53 the closing chamber 46 is connected to the 20 source of pressurized fuel (high pressure).

The upper (upper as in Figure 1) section of the spool 53 is formed as a piston section 73 with a diameter that is larger than the diameter of the rest of the spool 53 (in 25 other embodiments the diameter of the upper section 73 of the spool 53 is equal or smaller than the diameter of the rest of the spool 53). A pressure chamber 75 above (above as in Figure 1) acts on the spool 53 in the downward (downward as in Figure 1) direction to urge the spool 53 30 to the position where closing chamber 46 is connected to the source of pressurized fuel (high pressure) P.

Another pressure chamber 77 below (below as in Figure 1) the spool 53 acts on the on the spool 53 in the upward 12 DK 177456 B1 (upward as in Figure 1) direction to urge the spool 53 to the position where closing chamber 46 is connected to the outlet port 18 (drain). Pressure chamber 77 is permanently connected to the source of pressurized fuel P 5 via duct 17.

A restricted connection 82, e.g. in the form of a conduit with an orifice 84 that acts as a throttle connects pressure chamber 75 to duct 19 and thus to the tank port 10 18 (drain) .

The restricted connection can be opened and closed by a ball valve 85 that is connected to a spring biased solenoid 88. The spring of the ball valve 85 urges the 15 ball valve to its seat. Activation of the solenoid 88 causes the ball to be lifted from the seat against the action of the spring 89.

A restricted connection, e.g. in the form of a conduit 20 with 83 an orifice 8 6 that acts as a throttle connects pressure chamber 75 to duct 17 and thus to the fuel inlet port 16.

The position of spool 53 is controlled by fuel oil 25 pressure and the balance between the orifices 84 and 86.

When the solenoid 88 is activated the valve seat of the ball valve 85 is opened and pressure chamber 75 is connected to the outlet port 18 (drain) via the orifice 30 84. The fuel oil pressure in the pressure chamber 75 will drop because the flow area of orifice 86 is smaller than the flow area of orifice 84. The decrease pressure in pressure chamber 75 will cause the spool 53 to move upwards under influence of the pressure in pressure 13 DK 177456 B1 chamber 77 and closing chamber 46 will be connected to duct 19 and the outlet port 18 via control conduit 59.

Hence, the pressure in closing chamber 46 will drop and the fuel oil pressure in opening chamber 70 acting on 5 effective pressure area A2 will cause the valve needle 20 to move upwards (lift) and the fuel oil will pass via the valve seat 22 and thereby to the nozzle holes 35 for injection into a combustion chamber.

10 When the solenoid 88 is deactivated, the ball valve 85 will return to its seat by the action of the spring 89 and the pressure in pressure chamber 75 will rise by fuel oil passing through the orifice 86 and the spool 53 will start moving downwards since the effective pressure area 15 of pressure chamber 75 acting on spool 53 is larger than the effective pressure area of pressure chamber 77 acting on spool 53. When the spool 53 has moved a certain distance, control conduit 59 will be connected to conduit 57 which is in turn connected to duct 17 and thereby to 20 the source of pressurized fuel P. Hence the pressure in pressure chamber 46 will increase and cause the valve needle 20 to move downwards since effective pressure area A1 is larger than effective pressure are A2, until the valve needle 20 rests on its seat 22 and stops fuel oil 25 from going through via the valve seat 22 to the nozzle holes 35.

A ring chamber 93 below the piston section 73 is connected to duct 19 via a conduit 95 and hence to the 30 tank port. Thus, no force will act on the annulus area of the piston section 53.

14 DK 177456 B1

When there is no fuel oil pressure on the system the spring 23 will keep the valve needle 20 engaged with the valve seat 22.

5 By providing a pilot valve to control the position of the to the valve needle, the amount of leak fuel, during the time the valve needle has lift is significantly reduced.

The spool 53 acts as a 3/2 way valve, hence the spool 53 10 can be replaced by ball valve or a seat valve. Thus, in an embodiment the spool 53 is replaced by a ball valve and in another embodiment the spool 53 is replaced by a seat valve.

15 The solenoid 88 can in an embodiment be connected to an electronic control unit 50, such as the electronic control unit of the engine. Hence the electronic control unit 50 determines if the solenoid 88 is active or not and thereby the electronic control unit 50 controls the 20 start and end of a fuel injection event.

According to another embodiment the spool 53 is connected directly to an electronic actuator and then controlled according to the movement of the actuator.

25

Figure 2 shows an embodiment of the invention that is essentially identical to the embodiment of figure 1, except that the valve needle 20 is not provided with a cut off shaft. The construction of the nozzle 30 and the 30 valve needle is more simple than in the embodiment of Figure 1. However, the sac volume in the nozzle 30 is larger than in the embodiment of Figure 1.

15 DK 177456 B1

The embodiments described above can be combined in an desirable configuration.

The teaching of this disclosure has numerous advantages.

5 Different embodiments or implementations may yield one or more of the following advantages. It should be noted that this is not an exhaustive list and there may be other advantages which are not described herein. One advantage of the teaching of this disclosure is that it provides 10 for a fuel valve for a large two-stroke diesel engine that allows for precise control of a fuel injection event. It is another advantage of the present fuel valve that it reduces leak oil losses. It is yet another advantage of the of the present fuel valve that it 15 provide for a faster response of the valve needle on control signals.

Although the teaching of this application has been described in detail for purpose of illustration, it is 20 understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the scope of the teaching of this application.

25 The term "comprising" as used in the claims does not exclude other elements or steps. The term "a" or "an" as used in the claims does not exclude a plurality. The single processor or other unit may fulfill the functions of several means recited in the claims.

30

Claims

An electronically controlled fuel valve (1) for injecting fuel into the combustion chamber of a large two-stroke diesel engine with cross heads, the fuel valve comprising: 10 a fuel valve housing (10), a nozzle (30), a fuel inlet opening (16) for connection to a a high pressure fuel source (P), a first channel (17) connecting the high pressure fuel inlet opening (16) to the nozzle (30), a resilient biased and axially movable valve needle (20) cooperating with a valve seat (22) and configured to control the flow of fuel from the inlet opening (16) to fuel to the nozzle (30), whereby lifting of the axially movable valve needle (20) allows flow from the inlet opening (16) to fuel to the nozzle (30), characterized by 30, a closure chamber (46) in the valve body (10) which acts on the valve needle (20) with a first effective surface area (A1) and which forces the valve needle towards the valve seat ( 22) under pressure, an opening chamber (70) in the valve housing (10), which opening chamber is in fluid communication with the first duct to be pressurized by means of the high pressure fuel source (P), where the pressure in the opening chamber (70) act on the valve needle (20) with another effective surface area (A2) and force the valve needle (20) away from the valve seat (22), 10 a control channel (59) connecting the closing chamber with a valve opening to an electronically controlled control valve, which an electronically controlled control valve is provided with a valve opening connected to the tank opening (18) 15 and with a valve opening connected to the fuel inlet opening (16), which electronically controlled valve is configured to selectively connect the control channel (59) to 20 the tank opening (18) or with the fuel inlet opening (16) for electronically controlling the lifting of the valve stem (20).

The fuel valve (1) according to claim 1, wherein the electronically controlled valve is a firing valve.

The fuel valve (1) according to claim 1, wherein the electronically controlled valve is a ball valve or a seat valve. 30

The fuel valve (1) according to claim 2, wherein the firing valve is provided with a first pressure chamber (75) acting on a slider and (53) and forcing the slider (53) to a position where the control channel (59) is connected to the inlet port (16) for fuel.

The fuel valve (1) according to claim 4, wherein the firing valve 5 is provided with a second pressure chamber (77) which acts on the slider (53) and forces the slider (53) to a position where the control channel (59) is connected to the tank opening ( 18).

The fuel valve (1) according to claim 5, wherein the first pressure chamber (75) is provided with a first throttle connection (83) for the fuel inlet opening (16) and with a second throttle connection (82) for the tank opening (18), wherein the second throttle connection (82) 15 to the tank opening (18) is less restricted than the first throttle connection (83) to the fuel inlet opening (16), and the fuel valve (1) further comprises an electronically controlled electromagnetic valve for opening and closing the throttle connection to the tank opening. (18).

The fuel valve (1) according to claim 6, wherein the electromagnetic valve is an electromagnetically controlled ball valve (85). 25

A fuel valve (1) according to claim 6, wherein the restricted connection (82) to the tank opening (18) is located within the valve body.

A fuel valve (1) according to claim 2, wherein the slide valve (53) is connected to an electric actuator which controls the position of the slide (53). 4 DK 177456 B1

The fuel valve (1) according to claim 1, wherein the nozzle is a nozzle (30) having an axial bore and a closed front and the valve needle moves in harmony with a cut-off shaft (40) moving in harmony with the valve needle (20) and 5 is received axially slidably in the central bore (33) of the nozzle (30) for opening and closing the nozzle holes (35).