CN108368808B

CN108368808B - Leak detection device

Info

Publication number: CN108368808B
Application number: CN201580085069.1A
Authority: CN
Inventors: F·卡威莱斯
Original assignee: Wartsila Finland Oy
Current assignee: Wartsila Finland Oy
Priority date: 2015-10-09
Filing date: 2015-10-09
Publication date: 2020-06-30
Anticipated expiration: 2035-10-09
Also published as: EP3359801A1; EP3359801B1; KR20180059942A; CN108368808A; KR102068917B1; WO2017060561A1

Abstract

The leak detection device for detecting a leak in a fuel injection system includes: a fluid chamber (1) arrangeable in fluid communication with the leakage channel (2, 3); an indicator element (5) configured to move from a retracted position to a protruding position due to fuel pressure in the fluid chamber (1), thereby indicating a leak; and a retaining element (6) arranged around the indicator element (5) and configured to hold the indicator element (5) in the retracted position and to allow the indicator element (5) to move to the protruding position when a force applied to the indicator element (5) by the fuel pressure in the fluid chamber (1) exceeds a predetermined threshold. The device comprises a recess (7) arranged in a part (8) surrounding the indicator element (5) and configured to accommodate the retaining element (6).

Description

Leak detection device

Technical Field

The present invention relates to a leak detection apparatus for detecting a leak in a fuel injection system of an internal combustion engine.

Background

In fuel injection systems of internal combustion engines, the pressure may be very high, even up to 3000 bar. Leakage in the fuel injection system poses a serious hazard due to both high fuel pressure and fire risk. In order to increase the safety of the fuel injection system, the fuel piping and other components of the fuel injection system are usually provided with double walls. The inner wall defines the confines of an inner conduit within which fuel flows. A leakage path is formed between the inner wall and the outer wall. The leakage path is normally empty of fuel, but in the event of a leak in the inner conduit, the leakage path may receive leaked fuel. For safety reasons, it is important that leaks can be detected and repaired quickly. Different leak detection devices for detecting the presence of fuel in a leak channel are known. One known method for detecting a leak is to provide the leak channel with an indicator pin that is visible from outside the leak channel and is normally in a retracted position. When the leak channel is filled with fuel, the pressure inside the leak channel pushes the indicator needle to the protruding position, which indicates that the inner pipe is leaking. Thus, the leak can be visually detected. Because the engine vibrates during operation, the indicator needle is often provided with a snap ring or some other retaining element that prevents the needle from moving accidentally, but allows the needle to move if the force applied to the needle by the leaking fuel exceeds a certain threshold. When a leak is detected, the cause of the leak must be eliminated and the indicator needle needs to be set back to the retracted position.

A problem with the known indicator needle arrangement is that in order to set the needle back to its retracted position, it must be removed to bring the snap ring into the correct position. This is undesirable, especially in the case of an engine operating on methanol or some other toxic fuel.

Disclosure of Invention

It is an object of the present invention to provide an improved leak detection arrangement for detecting a leak in a fuel injection system of an internal combustion engine. The device includes: a fluid chamber disposable in fluid communication with a leakage passage configured to receive fuel from a leakage component of the fuel injection system; an indicator element having a retracted position and a projected position, the indicator element configured to move from the retracted position to the projected position as a result of fuel pressure in the fluid chamber, thereby indicating a leak in the fuel injection system; and a retaining element disposed about the indicator element and configured to retain the indicator element in the retracted position and to allow the indicator element to move to the protruding position when a force applied to the indicator element by the fuel pressure in the fluid chamber exceeds a predetermined threshold.

According to the invention, the device is provided with a recess arranged in the component surrounding the indicator element and configured to accommodate the retaining element.

Because of the groove, the holding element can be held in the same position during the movement of the indicator element. After a leak has been detected and repaired, the indicator element can thus be easily returned to the retracted position without disassembling any part of the leak detection device. This prevents fuel from escaping from the fluid chamber. This is beneficial especially in the case where the fuel injection system contains methane or some other toxic fuel.

According to one embodiment of the invention, the recess is arranged in a removable holding element, which allows mounting and dismounting of the indicator element. The retaining element may be a nut, for example. The removable retaining element allows the indicator element to be removed when required, for example to replace a seal of the leak detection apparatus.

According to one embodiment of the invention, the retaining element comprises a hole through which the indicator element protrudes, and one end of the hole is provided with a tapered section that tapers towards the interior of the retaining element. The tapered section of the bore allows for easy mounting of the retaining element.

According to an embodiment of the invention, the indicator element comprises a groove surrounding a periphery of the indicator element and configured to accommodate the retaining element when the indicator element is in the retracted position. Because of the groove, the threshold force required to move the indicator element from the retracted position to the protruding position is unambiguous. The function of the retaining element may also be based on friction, but in this case the indicator element may adopt an intermediate position between the retracted position and the protruding position, which is not desirable.

According to an embodiment of the invention, a front end of the indicator element in a direction from the retracted position towards the protruding position tapers towards the front end. When the indicator element is mounted, the tapered end of the indicator element allows the holding element to expand gradually, which makes it easier to assemble the leak detection device.

According to one embodiment of the invention, the holding element is a snap ring.

Drawings

Embodiments of the invention will be described in more detail below with reference to the accompanying drawings, in which:

fig. 1 shows a cross-sectional view of a connection for connecting three fuel lines of a fuel injection system to each other, the connection comprising a leak detection device according to an embodiment of the invention;

FIG. 2 illustrates an indicator element of the leak detection apparatus of FIG. 1; and

fig. 3 shows a holding element of the leak detection apparatus of fig. 1.

Detailed Description

Fig. 1 shows a sectional view of a connection piece 11 which can be used to connect three fuel lines of a fuel injection system to one another. In fig. 1, only one fuel channel 4 is shown. The connection piece 11 forms part of a fuel injection system of an internal combustion engine. The engine is a large piston engine such as a main engine or an auxiliary engine of a ship or an engine used for power generation at a power plant. The fuel injection system is configured to inject liquid fuel, such as light fuel oil, marine diesel, or methanol, into a cylinder of the engine. The fuel injection system may be, for example, a common rail fuel injection system. The fuel line 4 is a high-pressure line that can supply fuel to the fuel injectors, for example, from a high-pressure pump. Each fuel pipe 4 has a double-walled construction. Pressurized fuel is transported in the inner conduit and a leak path is formed between the inner conduit and the outer conduit. Should there be a leak in the inner conduit, the leaking fuel is received by the leak passage.

The connection 11 is provided with a leak detection device according to an embodiment of the present invention. The leak detection device comprises a fluid chamber 1, the fluid chamber 1 being in fluid communication with leak channels 2, 3. The connection 11 of fig. 1 comprises a first leakage channel 2 and a second leakage channel 3. Each leakage channel 2, 3 of the connection piece 11 is in fluid communication with a leakage channel of the fuel line 4. Thus, fuel leaking from the fuel pipe 4 is received by the leak passages 2, 3 of the connection piece 11. In the embodiment of fig. 1, each fuel conduit 4 may be connected to its own leakage channel 2, 3. This makes it easier to locate the leak. However, several components of the fuel injection system may also be connected to a common leakage channel 2, 3.

The leak detection device further comprises an indicator element 5. The indicator element 5 is a part which is movable in the direction of its longitudinal axis. The indicator element 5 has a first position and a second position. The first position is a retracted position and the second position is a projected position. When the leak detection device is assembled, the indicator element 5 is placed in the retracted position. The indicator element 5 is configured to move from the retracted position to the protruding position due to the fuel pressure in the fluid chamber 1. When leaking fuel flows to the fluid chamber 1 via the leakage channels 2, 3, the fuel pressure in the fluid chamber 1 pushes the indicator element 5 to the protruding position. The position of the indicator element 5 is perceptible from outside the leak detection device, so that a leak can be detected visually. The leak detection device may also be provided with a sensor monitoring the position of the indicator element 5, which will allow automatic leak monitoring. The fuel injection system may be provided with a plurality of leak detection devices. By connecting the leak detection means to only one or a few leak paths, leaks can be easily located.

The indicator element 5 has a first end and a second end. The first end of the indicator element 5 comprises a piston having a piston surface 12, the pressure in the fluid chamber 1 being applied to the piston surface 12. The piston surface 12 delimits the fluid chamber 1. An elongate rod 15 is connected to the piston of the indicator element 5. Indicator element 5 includes a first seal groove 13 and a second seal groove 14. The sealing

grooves

13, 14 are circumferential grooves arranged close to the first end of the indicator element 5. Each of the

seal grooves

13, 14 accommodates an O-

ring

16, 17. When the indicator element 5 is in the retracted position, the O-

rings

16, 17 are on opposite sides of a discharge line 18 perpendicular to the longitudinal direction of the indicator element 5. When the indicator element 5 is in the retracted position, the O-ring 16 located in the first sealing groove 13 prevents flow from the leakage channels 2, 3 into the discharge line 18. The O-ring 17 of the second sealing groove 14 prevents flow out of the discharge line 18 via the indicator element 5. In the protruding position of the indicator element 5, flow from the leakage channel 2, 3 into the discharge line 18 is allowed.

The leak detection means comprise a holding element 8 limiting the movement of the indicator element 5. The retaining element 8 allows the indicator element 5 to move between the retracted position and the protruding position, but prevents the indicator element 5 from falling out of the connection 11. In the embodiment in the figures, the holding element is a nut 8, the nut 8 being attachable to the connector 11 by means of a thread. However, the holding element 8 may also be a plate or a block or similar attached to the connecting piece 11, for example by means of bolts. The retaining element 8 comprises a hole 10 that can receive the stem 15 of the indicator element 5. In fig. 1, both indicator elements 5 are in the retracted position. In the retracted position, the second end of the indicator element 5 does not protrude beyond the retaining element 8. In the protruding position, the second end protrudes beyond the holding element 8, so that the indicator element 5 is easily detectable from the outside of the connection piece 11 in the protruding position. It is also possible for the indicator element 5 to project beyond the retaining element 8 in the retracted position. In this case, the stem 15 of the indicator element 5 may be provided with a marking clearly indicating whether the indicator element 5 is in the retracted position or in the protruding position.

Due to the vibrations of the engine, the O-

rings

16, 17 arranged in the sealing

grooves

13, 14 of the indicator element 5 cannot reliably hold the indicator element 5 in the retracted position. In order to prevent the indicator element 5 from accidentally moving from the retracted position to the protruding position and to avoid false alarms, the leak detection device is provided with a holding element 6. The retaining element 6 is engaged with both the indicator element 5 and the retaining element 8 and is configured to retain the indicator element 5 in the retracted position unless a longitudinal force applied to the indicator element 5 exceeds a predetermined threshold. Normal vibration of the engine thus does not displace the indicator element 5, but when the fuel pressure in the fluid chamber 1 is sufficient, the indicator element 5 can be displaced from the retracted position to the protruding position.

The holding element 6 is an elastic annular member such as a snap ring. When the retaining element 6 is not compressed or stretched, the outer diameter of the retaining element 6 is larger than the diameter of the bore 10 of the holding element 8 and the inner diameter of the retaining element 6 is smaller than the diameter of the bore 10. The indicator element 5 is provided with a groove 9 for receiving the holding element 6. The groove 9 surrounds the stem 15 of the indicator element 5. The cross-sectional shape of the groove 9 is circular. The cross-section of the groove 9 may be, for example, semicircular. The depth of the groove 9 is less than half the thickness of the holding element 6 in the radial direction. The shape and dimensions of the groove 9 allow the retaining element 6 to be moved out of the groove 9 when a sufficient axial force is applied to it. In addition, the holding element 8 is provided with a recess 7 for accommodating the holding element 6. The depth of the groove 7 of the retaining element 8 is at least the same as the thickness of the retaining element 6 in the radial direction. Thus, the holding element 6 can be completely received inside the groove 7 of the retaining element 8.

When the indicator element 5 is in the retracted position as shown in fig. 1, the retaining element 6 engages both the groove 9 of the indicator element 5 and the groove 7 of the retaining member 8. The holding element 6 is in a slightly expanded state. When the indicator element 5 is pushed towards the protruding position under the influence of the fuel pressure and the force exerted by the fuel pressure exceeds the force with which the retaining element 6 is held in the groove 9 of the indicator element 5, the retaining element 6 jumps out of the groove 9 of the indicator element 5. The form-locking between the holding element 6 and the indicator element 5 is thus released and the indicator element 5 can be moved towards the protruding position. The recess 7 now completely receives the holding element 6.

When a leak causing movement of the indicator element 5 is detected and repaired, the indicator element 5 needs to be returned to the retracted position. This can be done by simply pushing the indicator element 5 towards the retracted position. Since the groove 7 of the holding element 8 holds the holding element 6, the holding element 6 is not allowed to move together with the indicator element 5. When the indicator element 5 receives a position in which the groove 9 of the indicator element 5 is aligned with the groove 7 of the holding element 8, the holding element 6 is locked with the groove 9 of the indicator element 5. Due to the recess 7 of the holding element 8, resetting the leak detection device is easy and does not require any disassembly of parts.

One end of the hole 10 of the holding member 8 is provided with a tapered section 10a, which tapered section 10a tapers toward the inside of the holding member 8. The wider end of the tapered section 10a opens into the outer surface of the retaining member 8. The diameter at the wider end of the tapered section 10a is larger than the outer diameter of the holding element 6. This facilitates the insertion of the retaining element 6 into the groove 7 of the retaining element 8, since the retaining element 6 is gradually compressed when inserted into the groove 7. In the embodiment in the figures, the tapered section 10a is arranged at that end of the bore 10 which faces the fluid chamber 1 of the leak detection device.

In addition, the end of the rod 15 of the indicator element 5 is tapered. The indicator element 5 is thus tapered towards the second end of the indicator element 5. The indicator element 5 can be easily inserted into the hole 10 of the holding element 8, since the rod 15 of the indicator element 5 gradually expands the holding element 6 which has been inserted into the groove 7 of the holding element 8.

It will be appreciated by a person skilled in the art that the present invention is not limited to the embodiments described above, but that it may be varied within the scope of the appended claims. For example, the leak detection means in the figures are arranged in the connection piece, but the leak detection means may also be, for example, a separate module, which may be connected to a leak channel of the fuel line or some other component of the fuel injection system.

Claims

1. A leak detection apparatus for detecting a leak in a fuel injection system of an internal combustion engine, the apparatus comprising:

-a fluid chamber (1) arrangeable in fluid communication with a leakage channel (2, 3), the leakage channel (2, 3) being configured to receive fuel from a leaking component of the fuel injection system;

-an indicator element (5) having a retracted position and a protruding position, the indicator element (5) being configured to move from the retracted position to the protruding position due to fuel pressure in the fluid chamber (1) thereby indicating a leak in the fuel injection system; and

-a retaining element (6) arranged around the indicator element (5) and configured to hold the indicator element (5) in the retracted position and to allow the indicator element (5) to move to the protruding position when a force applied to the indicator element (5) by the fuel pressure in the fluid chamber (1) exceeds a predetermined threshold,

characterized in that the device is provided with a groove (7), the groove (7) being arranged in a component surrounding the indicator element (5) and configured to accommodate the retaining element (6), and the indicator element (5) comprising a groove (9), the groove (9) surrounding the periphery of the indicator element (5) and configured to accommodate the retaining element (6) when the indicator element (5) is in the retracted position.

2. The device according to claim 1, wherein the recess (7) is arranged in a removable retaining element (8), which allows mounting and dismounting of the indicator element (5).

3. The device of claim 2, wherein the retaining element is a nut.

4. A device according to claim 2 or 3, wherein the holding element (8) comprises a hole (10), the indicator element (5) protrudes through the hole (10), and one end of the hole (10) is provided with a tapered section (10a) that tapers towards the interior of the holding element (8).

5. The device according to claim 1, wherein a front end of the indicator element (5) in a direction from the retracted position towards the protruding position tapers towards the front end.

6. The device according to claim 1, wherein the holding element (6) is a snap ring.