WO2007049038A1

WO2007049038A1 - Fuel system test cell

Info

Publication number: WO2007049038A1
Application number: PCT/GB2006/003973
Authority: WO
Inventors: David Murray Macdonald
Original assignee: Moving Sun Limited
Priority date: 2005-10-25
Filing date: 2006-10-25
Publication date: 2007-05-03
Also published as: GB2432885A; GB0521669D0

Abstract

A fuel system test cell includes an element comprising at least one injector mounting bay and an injector mount removably mounted in the said injector mounting bay. Injectors mounted in the test cell are equipped with test equipment to measure injector performance.

Description

FUEL SYSTEM TEST CELL

Field of the Invention

The present invention relates to a fuel system test cell and in particular to a test cell for modelling the performance of fuel injectors.

Background of the Invention

One aspect of developing fuel systems for engines involves the testing the performance of fuel injectors. Currently, when new fuel injectors are to be developed special mounts and fixtures must be designed and manufactured so that the new fuel injector can be run and subjected to testing. The manufacture of such mounts and fixtures is time consuming as is the attachment of injectors to such mounts and fixtures, and their instrumentation.

The performance of a fuel injector depends on a number of factors including the characteristics of the fuel injector mount. Typically, the mounts and fixtures used during development of a fuel injector do not reflect the characteristics of a cylinder head of an engine in which the injector will be mounted.

The characterisation, testing, evaluation and endurance testing of fuel systems for automotive and truck engines in particular, and internal combustion engines in general, is an importance aspect of meeting emission and performance targets. The importance of consistent and correlated results across a wide range of equipment and sites is vital as small fluctuations in injector delivery rates and timings can have significant results on emissions.

It would therefore be desirable to provide an improved fuel system test cell.

The aim of the present invention is therefore to provide such an improved fuel test cell system. Summary of the Invention

According to one aspect of the invention there is provided a fuel system test cell including an element comprising at least one injector mounting bay. The element may comprise any number of injector mounting bays. Typically the number of bays would correspond to the number of cylinders of an engine. For example, the element may comprise eight bays in total, four being mounted on each side of a centre line. However, elements with twelve bays (six on each side of the centre line), sixteen bays (eight on each side of the centre line), or twenty bays (ten on each side of the centre line may be provided to simulate the configurations of engine that are produced. As mentioned later in the specification, the number of bays in the element can be more than the number of bays in which an injector is located, so that one element can be used to test injectors for use in a variety of different engine cylinder configurations.

Preferably the test cell includes an injector mount, said mount being removably mountable in the at least one injector mounting bay.

The injector mount may be sKdably mountable in the said mounting bay, and the mounting bay and injector mount may be provided with co-operating means to facilitate sliding of the injector mount into and out of the said mounting bay. The co-operating means may comprise a slide element projecting from the injector mount which engages with and is slidable in a groove in the injector mounting bay.

Another aspect of the invention provides an adaptor which provides for different types of injector to be placed into the said injector mount, or a similar mount forming part of another machine. For example, the same injector mount can be used to mount the injector is a production test facility. The test cell may include a range of adaptors, the outer shape of each adaptor of the range being substantially identical and the inner shape of the adaptor providing for location of a certain type of injector therein. Advantageously, die mass and general configuration of the said element is substantially similar to that of an engine cylinder head.

The test cell may further comprise a fuel distribution rail.

The test cell may further comprise a drive shaft, to one end of which a fuel pump or electronic injector drive means may be attached. The test cell may further comprise a drive means for driving¹ the drive shaft, which drive means may be an electric motor such as a traction motor or a pancake motor.

Advantageously, the said element is slidably mounted on a substantially fixed guide, the element and fixed guide each forming part of a slide. The drive shaft may include a coupling, one part of the coupling being formed in a part of the drive shaft mounted in the element, and the other part of the coupling being formed in a part of the shaft that is restrained against movement other than rotational movement of the shaft.

The test cell may comprise a member mounted to one side the said element, the member being movable towards and away from the said side of the element Preferably the said side is the underside of the element. Movement of the member towards and away from the element is caused by cams mounted on a rotatable shaft.

Preferably test equipment may be mounted in the said member, wherein with the said member brought up to the said element the injector projects into the test equipment.

Another aspect of the invention provides a method of testing comprising the steps of:

i. fitting an injector into an injector mount; ii. fitting an injector mount into an injector mounting bay of the element; iii supplying pressurised fluid to the injector; iv. measuring the output of the injector.

Another aspect of the method of the invention comprises the step of sliding an element preloaded with at least one injector mounted in an injector mounting bay onto a substantially fixed rail, and bringing test equipment into close proximity with the outlet end of said injector.

Brief Description of the Drawings

In the drawings, which illustrate a preferred embodiment of the invention and are by way of example:

Figure 1 is an assembly drawing of a fuel system test cell according to the invention;

Figure 2 is a schematic representation of a component of the test cell illustrated in Figure 1;

Figure 3 is a schematic representation of another component of the test cell in Figure 1;

Figure 4 is a schematic representation of a simulated cylinder head;

Figure 5 is a schematic representation of another component of the test cell in Figure 1;

Figure 6 is a cross-section al elevation of the test cell illustrated in Figure 1;

Figure 7 is a schematic representation of another component of the test cell illustrated in Figure 1;

Figure 8 is a schematic representation of another component of the test cell illustrated in Figure 1;

Figure 9 is a schematic representation of a sub-assembly of the test cell illustrated in Figure l; Figure 10 is a schematic representation of an injector mount of the test cell illustrated in Figure 1;

Figure 11 is a cross-section through the longitudinal centre axis of a test cell illustrated in Figure 1.

Detailed Description of the Pteferred Embodiments

Referring now to Figure 1 the fuel system test cell comprises a first member 1 which includes a U-shaped central element V with flanges V extending from the free ends of the U-shaped central element 1'. A rail 2 forms part of a large fixed frame (note shown). Typically, the frame would be fixed to a floor of a testing bay. The rail 2 extends through the U-shaped element 1' of the first member 1, the said first member 1 being arranged to be raised and lowered with respect to the said rail 2.

An attachment member 3 is located on the upper surface of the rail 2, the attachment member including on each side thereof a recess 3' and a projection 3".

Referring also to Figure 7, a second member 4 is slidably mountable onto and demountable from the attachment member 3. The second member 4 simulates a cylinder head of an engine, and provides eight injector mounting bays 5 formed by walls 6 projecting outward from a central portion

7 of the second member 4. The test cell includes means to allow an injector to be mounted in the injector mounting bays 5 by sliding an injector into a said bay 5. Sliding of the injectors into the injector mounting bays 5 is provided for by components mounted on the walls 6 and an injector mounting member.

Referring also to Figures 2 and 5, there are illustrated components 8 and 9. The component

8 is L-shaped and one such component 8 is fitted onto the upper and lower surfaces of the four end- most walls 6 of the second member 4, the components 8 each including a pair of spaced apart bores 8' which align "with threaded bores 6' in the walls 6. Screws (not shown) engage with the threaded bores 6' to fasten the components 8 to the walls 6. The components 9 are substantially U-shaped and include a pair of spaced apart bores 9' which align with threaded bores 6'. A component 9 is attached to each of the remaining walls 6 in the same manner as described above with reference to the components 8.

As can be seen from Figure 1, the dimensions of the components 8, 9 are such that a gap is left between the opposing end faces 8", 9" of the components mounted on the respective upper and lower surfaces of the walls 6. The gap forms a track 20 in which a projecting element of the injector mount can run as will be described in more detail below.

Referring also to Figures 3, 6 and 10, each injector 10 is mounted in an injector mount 11. Elements 12 project from each side of the injector mount 11 and engage with the track 20. The injector mount 11 includes aligned bores 13 and 15 in which an adaptor in the form of a collar 16 locates. The collar 16 includes a lower portion 16' of reduced diameter and a central bore 16" running axially through the collar. The central bore terminates at the base of the lower portion 16' in a bore of reduced diameter 17. The bores 13 and 15 are aligned, but bore 15 is of smaller diameter than bore 13, a step 14 forming the transition between the two. As can be seen from Figure 6, the lower portion 16' of the collar 16 engages in the bore 15.

As can be seen from Figure 6, the injector mount 11 includes a lower recess 18 in which a measuring device 19 may be located.

Referring now to Figures 6 and 8, the first member 1 includes four apertures 21, in each flange 1", and three apertures 22 in the lower part of the U-shaped element 1". In the configuration illustrated in Figure 6, the ends of the injectors pass through the apertures 17 in the collars 16 and into a measuring device 19 which is located in an aperture 21. The measuring device is of the type known as an Akribis TM, which measures the output characteristics of a fuel injector 10. The first member 1 is moveable towards and away from the second member 4 by means of a shaft 25. Four cams 26 are mounted on the shaft 25 and are aligned with blocks 27 attached to the base of the first member 1. Rotating the shaft 25 causes the first member 1 to reciprocate towards and away from the second member 4. With the test cell in the configuration illustrated in Figure 11, rotating the shaft 25causes the position of the cams 26 to change with respect to the position of the blocks 27 resulting in the first member 1 moving downwards away from the underside of the second member 4. As can be appreciated from Figure 6, such movement of the first member 1 away from the second member 4 results in the measuring devices 19 being drawn clear of the injectors 10 and the base of the second member 4, so that the said second member can be moved off the test cell and replaced by another second member which is pre-loaded with injectors for testing.

For testing purposes fuel is supplied to the injectors 10 by a pump not shown which is driven by shaft 32. An electrical traction or pancake motor 30 drives a stub-shaft 31, which in turn is connected to a drive shaft 32. Rotation of the drive shaft 32 causes fuel to be pumped through the common rail 33 to each of the injectors 10. The stub-shaft 31 and drive shaft 32 are each provided with one part of a two part coupling. When an operator slides a second member 4 onto the rail 3, the two parts of the coupling engage with one another to form a driving connection. Not all engines are of the common rail type. To facilitate testing of engines that use electronic injection units instead of connecting the end 35 of the drive shaft 32 to a high pressure pump, a means for driving the cams used to operate electronic injectors is fitted to the end 35 of the shaft 32, and the common rail is removed. Where a high pressure pump and common rail are used, preferably these components are the same or very similar to the components that will be used with the injector on an engine. Similarly, where the injectors are electronic the means for driving the cams of the electronic injectors is the same or similar to the means used with the injector on an engine. In this way the performance of the whole fuel system, i.e. the injectors, fuel pump, common rail, means for driving the cams of an electronic injector may all be tested together. The results for individual injectors will be much more accurate when the injectors are put in a production regime than would be the case if presently known testing techniques were used in testing injector performance.

Io the example shown the second member provides eight injector mounting bays 5, and one injector 10 is mounted in each bay. However, the test cell can be used with fewer injectors. If the injectors are to be used in an engine having four cylinders or fewer in line, each of the injectors 10 is placed in a mounting bay 5 on the same side of the second member 4. If the injectors are to be used in an engine whose cylinders are configured in a V or horizontally opposed formation, then injectors are mounted in injector mounting bays to on either side of the second member 4. For example, when testing injectors for use in an eight cylinder V formation engine the injectors would be mounted in the manner illustrated in Figure 1. Where the engine in which injectors are to be used is a V five formation, three injectors would be mounted in mounting bays 5 on one side of the second member 5 with two injectors mounted in mounting bays on die other side. In the case where the injectors are to be used in an engine whose cylinders are arranged in line and number more than four, four injectors would be mounted in mounting bays on one side and the remainder on die other side of the said second member.

One of the major advantages of the test cell of the present invention is that whilst one set of injectors is being tested another set can be mounted in injector mounts in another second member. As soon as testing of the first set of injectors is finished the first member is lowered so that the second member can be removed from the rail and replaced by another second member pre-loaded with injectors for testing.

Another advantage of the test cell of the invention is that the components better resemble an engine cylinder head than do the known testing apparatus.

Collars 16 in which the injectors are mounted are standardised to fit into the injector mounts 11, but internally are configured to receive specific injectors, and more significandy are designed for use in high volume test lines, i.e. the same adapter is used when testing an injector through the development phase of an injector as is used when the injector is in production.

Yet another advantage of the test cell of the invention is that injector mounts and second member as a whole mimic the vibration and mounting characteristics of the cylinder head of the engine into which injectors are to be fitted. This is achieved partly by making the mass of the second element and components mounted thereon match closely the mass of the cylinder head of the engine in which the injectors are to be mounted.

Also, the injectors can be fixed to the second element such that they are in a similar orientation and subjected to similar loads as when the injector is mounted in the cylinder head of an engine.

Claims

1. A fuel system test cell including an element comprising at least one injector mounting bay and an injector mount removably mounted in the said injector mounting bay.

2. A test cell according to Claim 1, further comprising an adaptor mountable in the said injector mounting bay and arranged to receive an injector.

3. A test cell according to Claim 2, wherein the adaptor is mounted in the injector mount.

4. A test cell according to any preceding claim, wherein the element includes at least one opening axially aligned with the position taken up by an injector mounted in the injector mount

5. A test cell according to any preceding claim, wherein the injector mount is slidably . mounted in the element.

6. A test cell according to any preceding claim, further including a drive shaft and a drive means.

7. A test cell according to Claim 4, further including a coupling in the drive shafζ wherein one part of the coupling is formed in a part of the drive shaft mounted in the said element and the other part of the coupling is mounted in a part of the drive shaft which is restrained against movement other than rotational movement of the said drive shaft.

8. A test cell according to any preceding claim, further comprising a common rail.

9. A test cell according to any preceding claim, further comprising a fuel pump or an electronic injector drive.

10. A test cell according to Claim 9, wherein the fuel pump or the electronic injector drive are driven by the drive shaft.

11. A test cell according to any preceding claim, wherein the element is mounted on a guide.

12. A test cell according to Claim 11, wherein the element and the guide each form a part of a slide which mounts the element slidably on the guide.

13. A test cell according to Claim 11 or 12, wherein the element comprises first and second members and wherein the first and second members are located to opposite sides of the guide.

14. A test cell according to Claim 13, wherein one of the first and second members is slidably mounted on the guide.

15. A test cell according to Claim 13 or 14, wherein one of the first and second members is mounted for reciprocal movement towards and away from the other of the first and second members.

16. A test cell according to Claim 15, further comprising at least one rotatably mounted cam, rotation of said cam generating the said reciprocal movement.

17. A test cell according to any preceding claim, wherein the element provides a number of injector mounting bays, wherein at least one injector mounting bay is located on either side of a longitudinal centre-line of the said element.

18. A test cell according to any preceding claim, wherein the element provides a number of injector mounting bays, the number being selected from the group comprising: eight, twelve, sixteen and twenty.

19. A test cell according to any preceding claim, wherein the mass of element is substantially similar to that of an engine cylinder head in which an injector to be tested is to be used.

20. A test cell according to Claim 13, wherein the member including the at least one injector mounting bay is of a mass substantially similar to that of an engine cylinder head in which an injector to be tested is to be used.

21. A method of testing a fuel injector comprising the following steps: i) fitting an injector into an injector mount of a fuel system test cell as claimed in any of Claims 1 to 20; ii) fitting the injector mount into an injector bay of the said fuel system test cell; ϋi) supplying pressurised fluid to the injector; iv) measuring the output of the injector.

22. A method of testing a fuel injector as claimed in Claim 21, comprising the further steps of: i) preloading the injector mounting bays of the element of the test cell with a desired number of injectors; ii) sliding the element onto a guide; and iϋ) bringing test equipment into close proximity -widi an outlet of the injector.

23. A fuel system test cell substantially as shown in, and as described with reference to, the drawings.

24. A method of testing a fuel injector substantially as shown in, and as described with reference to, the drawings.