WO2005038232A1

WO2005038232A1 - Leak alarm for high-pressure pipe

Info

Publication number: WO2005038232A1
Application number: PCT/FI2004/000578
Authority: WO
Inventors: Jari Renkonen
Original assignee: Wärtsilä Finland Oy
Priority date: 2003-10-17
Filing date: 2004-10-04
Publication date: 2005-04-28
Also published as: FI20031522A0; FI119702B; EP1680592B1; ATE464471T1; CN1867762A; KR101130388B1; FI20031522A; CN100430594C; DE602004026614D1; EP1680592A1; KR20060095758A

Abstract

The present invention relates to a high-pressure system in combustion engines and particularly to leak alarms. The idea is to connect the leak flow space of the high-pressure pipe via a valve to an expansion space and furthermore, to measure the pressure in the leak flow space. The valve provides the operatively necessary limitation of the volume of the flow space for pressure measurement and at the same time it acts as a discharge passage for possible over-pressure and leak fuel. A direct passage out of the engine may act as an expansion space. Another option is to use the channel for continuous leak connected to the fuel recycle system as an expansion space.

Description

LEAK ALARM FOR HIGH-PRESSURE PIPE

Field of invention

The present invention relates to high-pressure pipe systems for combustion engines. In particular, the invention relates to leak alarms.

Background of the invention

Many combustion engines, especially large combustion engines, comprise a fuel conduit/conduits, in which fuel flows at high pressure. These conduits are generally called high-pressure pipes. For instance in diesel engines it is known to arrange the fuel pipes inside another tubular sleeve in order to retain possible leaks inside the outer tubing. Should leakage occur in the system, the leak fuel will flow out of the engine inside the other sleeve. Such solutions are disclosed e.g. in EP A 0002385 and EP A 0786593.

For detecting leaks in corresponding arrangements e.g. various kinds of plugs have been used, by unfastening of which plugs the leak could have been detected. Another commonly used method has been the use of detachable hoses, by detaching of which it has been possible to detect the leak, as well. This known method is, however, most elementary, as the locating of the leak has been very slow and also laborious by using this method. Hoses or plugs need to be unfastened in turn till the leakage is possibly found sometimes.

The publication GB A 2060800 discloses a sort of fitting to be used in the double-walled fuel piping of an engine. By means of the fitting the leak fuel can be drained out of the flow space formed by the outer wall. According to the publication such fittings may be adapted in conjunction with the injector pump manifold and connect the outlets of the fittings to a common drain line. The fitting according to this specification is provided with a piston member, which in case of leakage is displaced so that the leak fuel can be directed through the fitting to the drain line and at the same time the pin of the piston member extends out indicating the leakage. It is, however, difficult to apply this arrangement particularly to a large engine provided with a common rail storage injection system, where the fuel piping is extensive and has many branch pipes. By using the disclosed solution the system becomes, among other things, very scattered and therefore difficult to use and maintain.

A more advanced fuel feed system is shown in Fig. 1 . The figure shows schematically a section of the fuel feed system of a combustion engine, especially a large combustion engine. By a large combustion engine is meant for instance such engines that are applicable e.g. as main or auxiliary engines on ships or at power plants for producing heat and/or electricity. Generally, the large engines are diesel engines. More precisely, Fig. 1 shows an example of a so-called common rail diesel engine.

The combustion engine is shown here, for the sake of clarity, very schematically and it may be a known engine as such. It is mainly the cylinders 13 and cylinder heads 1 2 that are shown a bit in more detail. In two of the cylinders also a piston 23 is sho wn in its upper position. Fuel is supplied from a fuel tank 2 by means of a fuel delivery pump 1 via fuel piping 3 to each high- pressure pump 4, which in turn raises the fuel pressure to such a level that a sufficient injection pressure is provided for injectors 1 1 . The high-pressure pumps 4 are in communication with pressure accumulator units 6, into which the fuel is fed by means of the high-pressure pump. From the pressure accumulator unit fuel is conducted further to the injectors 1 1 by means of a fuel manifold 7.

From the nozzle 1 1 at the cylinder head some fuel is continuously leaking and it is led through a leak pipe 1 to a channel 1 5 for continuous leak, which is connected to a fuel recycle system. Also in the high-pressure pump 4 some normal leakage occurs and is led via a leak pipe 24 to a leak channel 1 5. Thus, the example in Fig. 1 comprises preferably an assembly, where the fuel is delivered by means of a high-pressure pump 4 to a pressure accumulator unit 6, from where the fuel is further fed by means of the injectors 1 1 to engine cylinders 1 3. Each of the pressure accumulator units 6 is connected at least with two injectors 1 1 and provided with a high-pressure pump 4 of its own. The high-pressure pump 4 and the pressure accumulator unit are connected by a fuel feed pipe 5, the pressure accumulator units 6 and the injectors 1 1 by a fuel manifold 7, and the pressure accumulator units by connecting lines 8 for fuel, whereby at least the fuel feed pipes 5 and the fuel manifold 7 as well as the connecting lines 8 for fuel are formed of double- walled tube, the outer flow spaces 10 (for leak fuel) of which can be connected to each other. Thus, in case of leakage somewhere in the system, the leak fuel may flow along the outer flow space 10 and an outlet flow channel 20 to a leak tank 21 and to a leak indicator 22 connected thereto. The leak indicator, being e.g. a float or an optical sensor indicating the filling of the leak tank, detects the leak. The leak fuel is conducted out of the engine 's leak tank via a throttle pipe 27. The actual fuel being at a high pressure flows inside an inner flow space 1 1 O.

For locating the fuel leakage point the connecting line 8 for fuel is equipped with at least one detector apparatus 1 8 for leak fuel being in communication with the outer flow space of the piping possibly by means of a connecting line 1 7. The detector apparatus 1 8 for leak fuel comprises members for identifying leakage, by means of which members the outer flow spaces can be either coupled into flow connection with one another or disconnected from one another. The detector apparatus is further connected by means of a connecting line 1 9 with the outlet flow channel 20.

As shown further in Fig. 1 , the connecting line 8 for fuel, which connects the pressure accumulator units 6 in the fuel feed system are fitted with a partition wall 9 or the like, by which the outer flow space 1 0 of the feed system and the feed system itself are divided into separate departments, two of which are shown herein, and the first of which comprises one of the pressure accumulator units and the injectors connected thereto as well as a fuel delivery pump, and correspondingly, the second one comprises the other pressure accumulator unit and the injectors connected thereto as well as a fuel delivery pump, and the outer flow space 10 of both departments is connected to the detector apparatus 1 8 for leak fuel. In this case the detector apparatus 18 for leak fuel arranged in the connecting lines for fuel is not, however, always necessary, but in some fuel feed systems and engines the locating of leakage can be carried out only by using primarily the detector apparatus for leak fuel arranged in conjunction with the pressure accumulator units 6.

The area 25 outlined with a dashed line in Fig. 1 depicts a so-called hotbox of the engine. Thus, the figure shows the devices placed inside the hotbox.

Fig. 2 shows a cross-sectional view of the hotbox. The hotbox is an area restricted by a cover 28 a nd the engine 's body and other parts 29 thereof, which area utilises the heat energy produced by the engine. Since the cover can be opened, the condition of the devices can be easily checked. The indicating apparatus 18 for leak fuel with necessary connecting lines 1 7, 1 9 are, for the sake of simplicity, indicated merely by pipe 210. Fig. 2 is a simple principal diagram and therefore does not illustrate all possible devices arranged in the hotbox. Fig . 3 shows a combustion engine 31 seen from outside. The hotbox is normally located at the upper edge of the engine, where its cover 28 can be opened .

Fig. 4 shows still another application of the detector apparatus for leak fuel. It shows by way of example a detail for locating leakage in a high-pressure pipe 5, 7, 8, i.e. at the joining point of the high-pressure pipe (e.g. at the cylinder head or in the pressure accumulator unit) . In this embodiment there is a pin 41 with a matching pin housing 42, and a spring-loaded ball 43 or the like adapted in conjunction with the outer flow space 10 in the pressure accumulator unit 6. The spring-loaded ball 43 or the like maintains the normal position of the pin by means of a groove or the like (not shown) arranged in the pin and being in cooperation with the ball or the like . Should leakage occur for instance in pipe 8 (or in other high-pressure pipes, the outer flow space of which is by means of separate channels connected to pipe 8 shown in Fig. 4), the pressure starts rising in the pressure space 44 of the pin housing. By an appropriate design of the spring-loaded ball 43 or the like and of the groove or the like in cooperation therewith, it is possible to determine the pressure in the pressure space 44, at which the pin starts moving outwards in the pin housing 42 till the situation shown in Fig. 4 is achieved, where the leak fuel is allowed to discharge via a channel 45 forward, up to a leak indicator device 22. Thus, the pin acts here as a member of action arranged in conjunction with the wall of the pressure accumulator unit 6, the position of which pin with respect to the pressure accumulator unit is changeable by the impact of the leak fuel pressure, and on the basis of the position of which pin with respect to the pressure accumulator unit the flow of the leak fuel can be conducted in the outer flow space of the fuel piping for detecting the leakage . In the solution according to this embodiment leak fuel does not come out of the system even at the locating stage, but the leak is indicated by the pin protruding from the body. As it will be observed from Fig. 4, the use of pins requires relatively complicated and expensive arrangements.

One of the problems related to the known concepts is also the fact that the delay between the start of leakage and the alarm is relatively long. The amount of the leak liquid is small relative to the volume of the leak passage, whereby it takes a fairly long time before the alarm device (e.g. a leak indicator in conjunction with the leak tank) reacts. Moreover, in some engine types the leak channel of the high-pressure piping is located outside the hotbox, whereby it needs to be cleaned after each alarm, as the leak fuel has plugged it. Fairly often the throttle channel in conjunction with the leak tank is also adjusted incorrectly with respect to the leak of the high-pressure pipe. Brief description of the invention

An object of the present invention is to eliminate the above-mentioned problems related to prior art. The object is achieved as is described in the claims. The idea of the invention is to connect the leak flow space of a high-pressure pipe through a valve to an e xpansion space and in addition, to measure the pressure prevailing in the leak flow space. The valve, e.g. a check valve, provides the operatively necessary limitation of the volume of the flow space for measuring the pressure, and at the same time it acts as an outlet port for possible over-pressure and leak fuel.

A direct passage out of the engine (e.g. a channel structure or a pipe) may act as an expansion space, whereby the possible leak fuel (and the overpressure produced at the same time) is allowed to discharge to the environment. For practical arrangements it is preferable to fit a collecting vessel for leak fuel in conjunction with the outlet. Another advantageous alternative is that the channel for continuous leak connected with the fuel recycle system will act as an expansion space. The advantage with the channel for continuous leak is the fact that it is ready-fitted in the engine, whereby it is fairly easy to arrange a leak pipe including a valve between the high-pressure pipe and the channel for normal leak. Then, the combined volume of the leak pipe and the leak flow space, limited by the valve, makes the volume, in which the pressure sensor measures the pressure.

Thus, the invention relates to an apparatus in a combustion engine for leakage in a high-pressure pipe, which apparatus comprises at least one valve and at least one pressure sensor, in which apparatus a leak pipe is connected via the valve to an expansion space, and in which apparatus the pressure sensor is connected to a common flow space of the leak pipe and an outer flow space. List of drawings

In the following the invention is described with reference to the attached drawings, in which

Figure 1 shows an example of a prior art apparatus for leakage in a high- pressure pipe;

Figure 2 shows an example of the apparatus according to Fig. 1 in cross direction;

Figure 3 shows an example of a combustion engine seen from outside;

Figure 4 shows an example of an indicator pin for leak fuel;

Figure 5 shows an example of an apparatus according to the invention; and

Figure 6 shows an example of the apparatus according to Fig. 5 in cross direction.

Description of the invention

Fig. 5 shows an example of an apparatus according to the invention. The apparatus is based on the apparatus shown in Fig. 1 , but it has been modified so as to comply with the invention. In this example the outer flow space 1 0 of a high-pressure pipe 8 connecting pressure accumulator units 6 is connected via a leak pipe 53 with the engine 's channel 1 5 for continuous leak. The leak pipe is provided with a valve 51 , preferably a check valve, by which the total volume of the outer flow space and the volume of the leak pipe attached thereto can be limited. It is to be noted that only that part of the leak pipe volume, which is located between the valve and the high-pressure pipe is included in the total limited volume. The pressure in the total limited volume is measured by a pressure sensor 52. The pressure sensor is preferably provided with an output for transmitting pressure measurement data for instance to a control centre. In case of leakage in the high-pressure pipe, the pressure in the volume limited by the valve will show a rapid increase, on which the pressure sensor will react. Thus the delay between the leakage and alarm is as short as possible.

The fuel leaking to the outer flow space, i.e. the leak fuel, is allowed to discharge through the valve 51 , which will open due to the increased pressure, to the channel 1 5 for continuous leak. Thus, the valve does not only provide a limited volume (i.e. a common flow space formed by the leak pipe and the outer flow space), but it also offers the leak fuel a drain port out of the engine. The apparatus is provided with a pressure sensor.

It is shown in Fig . 5 that the high-pressure pipe 8 is divided by a separating element 9 (partiti on wall) into two separate volumes. The pressure in the first volume is measured by a pressure sensor 52 attached to the leak pipe 53 and the second volume by a sensor attached directly to the high-pressure pipe 8. The location of the pressure sensor is thus dependent on the architecture of the syste m provided that it is connected to the volume exposed to measurement. Also the leak pipe 53 may be realized in a way suitable for the application. It may be e.g. a channel drilled/milled in the constructions.

Also the location of the valve 51 is dependent in the architecture of the system. The leak pipe may be quite short, whereby the location of the valve has no alternatives, or the leak pipe may be long, whereby the location of the valve is freer. Fig . 6 shows the apparatus according to Fig. 5 in cross direction. Figs. 5 and 6 reveal that the channel for normal leak is preferably located inside the hotbox. It is also possible that the leak pipe/pipes are in connection with a channel (if it is preferable to have one), which forms an immediate, or as direct as possible, path out of the engine. Thus it is not necessary that the channel for continuous leak, which is connected to the engine 's fuel recycle system, is used for transferring the leak fuel from the high-pressure pipe out of the engine. In an extreme case the leak pipe itself may form a channel out of the engine. The choice of the structural concept to be used is dependent on the rest of the engine structure. The channel for continuous leak is, though, ready-fitted in most engines, whereby the use thereof is motivated. A direct discharge passage for leak fuel, on the other hand, is preferably provided with some kind of a collecting vessel for leak fuel outside the engine in order to avoid contamination of the environment. A conventional concept for most engines is thus to utilise the existing channel for continuous leak.

In the embodiment according to the invention, where the channel for normal leak located inside the hotbox is employed, no separate cleaning of the channels after the alarm is required. The heat of the hotbox keeps the leak fuel in the channel fluent and thereby it does not solidify. After the leak, the leak channels are thus in good condition and ready for next leakage, should any occur. So, it is advantageous to arrange the operational members, the pressure sensors and valves included, in the hotbox.

Since the measurement is carried out by a pressure sensor/sensors, neither a leak tank 21 nor a throttle channel 27 connected therewith is required.

The pressure in the inner flow space . of the high-pressure pipe is generally max. about 1 600 bar (in CR engines), and therefore this pressure, in case of pipe fracture, will discharge into the outer flow space 10 and therethrough into the lea k pipe 53, whereby the pressure is also decreased. Due to the pressure increase the valve will open so as to allow pressure release to an outside space, which is called an expansion space in this context. As can be concluded from the described embodiments, a direct passage out of the en- gine or a channel for continuous leak connected to the fuel recycle system of the engine may act as an expansion space. Also other structural concepts are conceivable for the required expansion space. The impact of the pressure in the leak fuel discharge channels needs to be taken into account before the arrangement according to the invention may be realised. If the pressure is not taken into account, the engine is susceptible to breakage.

As the pressure in the high-pressure pipe is allowed to discharge sufficiently fast to a sufficiently large volume, the dimensioning of the leak pipes and used channels does not cause any problems. The pressure sensor can operate by a distinction of e .g. 0.1 bar and the valve by a distinction of 0.2 bar. Thus a more secure operation of the pressure sensor is enabled before the pressure and leak fuel are allowed to discharge to the expansion space. Also the other operating parameters for the pressure sensor and valve are possible .

Some cost saving is achieved by the engine structure according to the invention, as a separate channel system or an actuator is no longer needed. By comparing Fig. 5 with Fig. 1 it is observed that the detector apparatus 1 8 for leak fuel with the necessary connection lines 1 7, 1 9, the outlet flow channel and the leak tank 21 with the required equipment are unnecessary in the structural conception according to the invention. The costs of the pressure sensor and valve are lower than the saved costs.

It is also possible to arrange an individual control for each cylinder in the engine, whereby the combination of a pressure sensor and a valve is connected to each cylinder's injector pipe, i.e. high-pressure pipe, which supplies fuel to the cylinder. The pressure sensor and/or the valve may also be connected to the high-pressure pipe between the high-pressure pump and the pressure accumulator unit or to the high-pressure pipe between the pressure accumulator units. Thus the invention provides a shorter delay between the leakage and alarm, as well as less expensive structural conceptions. Moreover, the invention decreases the need for maintenance and adds to reliability, since the leak channel system need not to be cleaned after possible leakage.

The above-described embodiments of the detector apparatus for leak fuel are independent, but it is indeed possible to choose for the same engine several basic concepts operating according to different embodiments. In the scope of the present invention it is also possible to combine the operational principles of various embodiments. The engine may be a standard engine, common rail engine or another type of engine. The engine may be any combustion engine, but preferably it is a diesel engine.

It is thus clear that the above-described technical solutions are shown only by way of example, and therefore the invention is not limited to the above- described embodiment, but several other modifications are conceivable within the scope of the appended claims.

Claims

1 . An apparatus in a combustion engine for leakage in a high-pressure pipe, in which apparatus the high-pressure piping consists of double-walled fuel piping comprising an inner flow space for fuel and an outer flow space for possible leak fuel, and which apparatus comprises at least one leak pipe in communication with the outer flow space, through which leak pipe possible leak fuel is led out, characterised in that the apparatus comprises at least one valve and at least one pressure sensor, the valve and the pressure sensor being separate parts, in which apparatus the leak pipe is connected via the valve to an expansion space, and in which apparatus the pressure sensor is connected to a common flow space of the leak pipe and the outer flow space, in which case, due to possible leak fuel, increased and/or increasing pressure in the common flow space is detected in the pressure sensor for an alarm and opening of the valve is performed for draining the leak fuel to the expansion space.

2. An apparatus according to claim 1 , characterised in that the expansion space is formed by a channel for the continuous leak from the engine and it is in communication with the fuel recycle system of the engine.

3. An apparatus according to claim 1 , characterised in that the expansion space is formed by a passage out of the engine.

4. An apparatus according to claim 1 or 3, characterised in that the leak pipe/pipes, valve/valves and pressure sensor/sensors are located inside a hotbox.

5. An apparatus according to claim 2, characterised in that the leak pipe/pipes, valve/valves and pressure sensor/sensors and the channel for continuous leak are located inside a hotbox.

6. An apparatus according to claim 2 or 5, characterised in that the channel for continuous leak is connected by piping with the fuel recycle system.

7. An apparatus according to any one of claims 1 - 6, characterised in that the pressure sensor is provided with an output for transmitting measurement data from the pressure sensor.

8. An apparatus according to any one of claims 1 - 7, characterised in that the pressure sensor and/or the valve is connected to the high-pressure pipe, which supplies fuel to the cylinder.

9. An apparatus according to any one of claims 1 - 7, characterised in that the pressure sensor and/or the valve is connected to the high-pressure pipe between a high-pressure pump and a pressure accumulator unit.

1 0. An apparatus according to any one of claims 1 - 7, characterised in that the pressure sensor and/or the valve is connected to the high-pressure pipe between the pressure accumulator units.

1 1 . An apparatus according to any one of claims 1 - 1 0, characterised in that the valve is a check valve.

1 2. An apparatus according to any one of claims 1 - 1 1 , characterised in that the combustion engine is a common rail engine.

1 3. An apparatus according to any one of claims 1 - 1 2, characterised in that the combustion engine is a diesel engine.