GB2333323A

GB2333323A - Fuel line press-fit pressure diagnostic port

Info

Publication number: GB2333323A
Application number: GB9800702A
Authority: GB
Inventors: Michael John Lewis
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1998-01-15
Filing date: 1998-01-15
Publication date: 1999-07-21
Anticipated expiration: 2018-01-15
Also published as: GB2333323B; GB9800702D0

Abstract

The present invention relates to a fuel line arrangement for a motor vehicle, having a press-fit fuel pressure diagnostic port, and to a fuel line pressure measurement apparatus including a connection to the port. The fuel line arrangement comprises a plastic material fuel conduit 16, a moulded diagnostic port 26 integrated with the fuel conduit, the port comprising a housing 34 having a pressure sampling valve 46, in which the housing 34 has around an external periphery of the housing an annular latching feature 90. A connector 30 has a latch mechanism 80 for engaging with the latch feature 90 when a pressure-tight connection is made between the port 26 and the connector 30, so that a fuel pressure measurement may be made.

Description

Fuel Line Press-fit Pressure Diagnostic Port The present invention relates to a fuel line arrangement for a motor vehicle, having a press-fit fuel pressure diagnostic port, and to a fuel line pressure measurement apparatus for connection to the port.

If a motor vehicle engine is serviced or repaired, one measurement that may be made is a check of the pressure in the fuel line supplying the engine. This is particularly the case for fuel injection engines. Such fuel lines therefore may have a diagnostic port to which pressure measurement apparatus may be attached.

One such prior art port is disclosed in GB 2 243 432 A, in which a fuel line connector is provided between the fuel rail and either a fuel inlet or a fuel outlet line in a recirculating fuel supply system. The connector is formed in one piece from a metal, and therefore has screw thread fitting for connecting both the connector to the fuel rail, and a measurement device to he connector.

An advantage of such a connector is that it avoids the need to drill or otherwise machine a metal fuel rail, which could contaminate the rail with metal swarf.

Whilst such a connector between a fuel rail and supply/return line is effective, the need to cast or forge and then machine a metal connector means that such connectors are relatively expensive.

Accordingly, the invention provides a fuel line arrangement for a motor vehicle, comprising a plastic material fuel conduit, a moulded diagnostic port integrated with the fuel conduit, the port omprising a housing having a pressure sampling valve, in which the housing has around an external periphery of the housing an annular latching feature.

The moulded diagnostic port may be integrally moulded with the fuel delivery conduit, for example a fuel rail, or the port may be glued or ultrasonically welded to make a permanent bond between the port and the conduit. Such an integrated form of construction may be more economical than a form using threaded connectors and metal components.

Preferably, the annular latching feature is a ridge on a cylindrical portion of the housing.

The housing has an aperture leading to the valve, the valve having inside the aperture a plunger which may be moved to open the valve by a pin inserted into the aperture.

Also according to the invention, there is provided a fuel line pressure measurement apparatus, comprising a fuel line arrangement according to the invention, and means for making a fuel pressure measurement, said means including a connector that has a latch mechanism for engaging with the latch feature when a pressuretight connection is made between the port and the connector.

The connector may then advantageously be latched to the port in a press-fit engagement.

It will normally be necessary to provide sealing means between the connector and the port, which make a pressure-tight seal before or as the connector is latched to the port. In a preferred embodiment of the invention, the connector has a cylindrical body portion, with a pair of axially spaced o-ring seals, said seals making a pressure-tight fit with an external surface of the housing prior to the engagement between the latch mechanism and the latch feature.

Preferably, the connector has a body, which is moulded, for example a body, which is integrally moulded, or moulded from a number of components, glued or ultrasonically welded together.

In a preferred embodiment of the invention, the connector has around an external periphery of the connector an annular ridge, and the latching mechanism is a hollow ring that is retained on the connector by the ridge, and which has an engagement feature that latches with the latching feature. The hollow ring may be moulded, for example from the same material as the rest of the connector.

The ring may have a generally cylindrical body with a radially inward directed lip at one end of the body that retains the ring on the ridge. The other end of the body then has one or more radially inward directed detents or other such latching means that act as the engagement feature.

Preferably, there are a pair of detents which oppose each other across the hollow of the ring, the ring being flexible so that the ring may be deformed to increase the separation between the detents to aid latching or unlatching of the detents from the latching feature. Such a deformation may then readily be made by squeezing the ring by hand between a pair of points midway between the detents. The connector may then be press fitted to the port, or removed from the port, more quickly than may be the case with a threaded connection.

Preferably, however, the ring is formed so that there is no need to squeeze the ring when it is press fitted to the port. One way in which this may be accomplished is if the detents and the latching feature have surfaces which cooperate to expand the separation between the detents when the ring is pressed axially to the latching feature. The ring may then automatically snap over the latching feature as the connector is press- fitted to the port.

Once the connection is made, the valve has already been activated to release fuel under pressure to a pressure gauge mounted either directly to the connector, or in communication with the connector through a conduit such as a flexible hose.

The invention will now be further described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a four cylinder internal combustion engine with a fuel rail connected to the engine, showing two locations for a pressure diagnostic port according to the invention; Figure 2 is a cross section view of a pressure diagnostic port and a connector having a latch for making a press-fit engagement with the port; and Figure 3 is a plan view of the latch and port, taken along the line III-III of Figure 2.

Figure 1 shows an internal combustion engine 10 with an inlet manifold 12 and an exhaust manifold 14. A fuel rail 16 is mounted to the inlet manifold side of the engine. A fuel inlet pipe 18 introduces fuel to the rail 16, and an outlet pipe 20 returns fuel to the tank (not shown). From the rail, 16, fuel is supplied to fuel injectors 22, one for each cylinder 24. Together with the fuel rail 16, in the inlet and outlet pipes 18,20 define a fuel supply circuit for the engine 10.

In the fuel line arrangement according to the invention, one moulded diagnostic port 26 is provided at a point in the fuel supply circuit. Figure 1 shows two possible locations for the port 26, one on the fuel rail 16, and one on the fuel delivery pipe 18. In either case, the port 26 is integrated with the respective part of the fuel supply circuit, which would then be formed from a plastic material. If it were desired that the fuel rail be formed entirely from a metal, then the port 26 would be sited either on the fuel inlet pipe 18 or the fuel outlet pipe 20.

Figure 2 shows the moulded diagnostic port 26, when this is integrally moulded with a plastic fuel rail 16, and also a moulded plastic material connector 30 which may be press-fitted with the port 26, as indicated by arrow 32, along a common axis 47.

The port 26 has a cylindrical body portion 34, which extends at a right angle to the axis of the fuel rail 16. The port 26 has inside its free end 35 a moulded plastic retention plug 36 with an axial bore 33 therethrough. The port is ultrasonically bonded to an inside cylindrical surface 38 of the port body portion 34, and so the body portion 34 and the plug 36 together define a housing for a valve. The inside cylindrical surface 38 has an annular rebate 40 so that the plug 36 may be fitted flush with the body portion free end 35.

Prior to ultrasonic welding of the plug 36 to the body portion 34, a metal spring 42 is inserted into the body portion, the end of the spring being seated within an annular groove 44 around the inside base of the body portion 34. A moulded plastic one-way pressure sampling valve 46 is then seated atop the spring 42, the plug 36 then compressing the spring 42 as the plug is inserted into the body portion so that the valve is spring biased towards the plug.

The three moulded components of the port 26, the body portion 34, the plug 36 and the one-way valve 46 are all circularly symmetric about the common axis 47.

The one-way valve 46 has a lower cylindrical portion 48 that projects inside the spring 42 and which has an annular shoulder 50 on which the spring bears.

Beyond the shoulder 50, the valve has a frustoconical tapering portion 52 with an annular groove 54 in which a nitrile o-ring 56 is seated. The plug 36 has a frustoconical surface 58 that matches the one-way valve tapering surface 52, so allowing the o-ring 56 to make a seal between the plug 36 and the valve 46 as the valve 46 is spring biased towards the plug 36.

A plunger in the form of a stem 60 extends axially from the narrower end of the valve tapering surface 52, projecting into the bore 33. When the stem is pressed axially inwards against the spring bias, the one-way valve opens 46 as the o-ring 56 is moved away from the plug tapering surface 58. There is sufficient clearance between the shoulder 50 and the housing inner wall to permit fuel to escape under pressure past the valve and through the bore whenever a fuel pressure measurement is made. The stem 60 is slightly recessed within the bore 33 to help prevent accidental release of fuel.

When the valve is fully opened, the lower surface 62 of the valve abuts the top of an inner wall 64 of the annular groove 44 around the inside base of the body portion 34. The maximum movement of the valve 46 is thereby limited to prevent the spring 42 from becoming over-compressed.

As the spring 42 is compressed, the clearances between the spring 42 and respectively the valve lower cylindrical portion 48 and the groove inner wall 64 serve to keep the spring straight and prevent the spring from twisting and catching with the plug lower surface 62.

Referring now to both Figures 2 and 3, the connector 30 has a body portion 70, the end of which 71 is circularly symmetric about the common axis 47. A pair of nitrile o-ring seals 72,73 is seated within a pair of axially spaced grooves 74,75 within an opening 76 to the connector 30. When the connector 30 is press fitted to the port 26, the o-ring seals 72,73 make a pressuretight seal with the port body portion 34.

The connector has an annular ridge 78, which extends fully around the end 71 of the connector. The ridge 78 retains a latching mechanism in the form of a generally cylindrical hollow ring 80 moulded from a resiliently flexible plastic material. At one end the ring 80 has a radially inward directed lip 82 that retains the ring on the ridge, and at the other end the ring has a pair of opposed radially inward directed detents 83,84.

Each detent has a straight latching edge 85 that extends as a chord across the circular periphery of the ring 80. From the common axis 47, each chord subtends an angle of about 900.

The connector has an elbow 82 from which an upper part 84 of the connector body portion 70 extends at right angles to the common axis 47. Although not illustrated, a flexible hose may then be joined to the connector body 70, and lead to a pressure measurement gauge.

The connector 30 has an internal projection 86 from an inner surface 88 of the body portion upper part 84, the projection extending towards the connector opening 76 along the common axis 47. The projection 86 does not extend towards the opening 76 as far as the innermost connector o-ring 73.

When the connector is moved axially so that the port body portion 34 enters the connector opening 76, both connector o-rings 72,73 initially make a sealing contact with the port body portion 34. As the port body portion 34 continues to enter the connector, the projection 80 acts as a pin to make contact with the valve stem 60, and begins to press this inwards, until the seal made by the valve o-ring 56 is broken, thereby allowing fuel under pressure into the connector 30.

Finally, the detents 83,84 of the connector ring 80 come up against a latching feature on the port 26 in the form of an annular ridge 90 that extends around the full periphery of the port body portion 34. Each detent has an arcuate tapering surface 92 along the central portion of the detent straight edge 85, which cooperates with the ridge 90 to force the detents outward, until each straight edge 85 snaps into engagement behind the ridge 90, thereby latching the connector to the port 26.

After the fuel pressure measurement has been made, the connector 30 may be removed from the port 26. Because the ring is resilient and flexible, it may be squeezed in a radial direction by hand, as represented by the arrows 94. This causes the ring 80 to deform such that each detent 83,84 moves radially outwards, as represented by the arrows 96, until the separation between the detents is sufficient to clear the ridge 90, and permit the connector 30 to be disconnected from the port 26. During disconnection, the valve o-ring 56 makes a seal prior to point at which the connector orings 72,73 break the seal between the connector 30 and the port 26, thereby preventing the escape of excess fuel. Some small amount of fuel that has entered the connector opening 76 during the pressure measurement may, of course, be lost.

The fuel line arrangement and pressure measurement apparatus described above may be economically made using moulded plastic material components. The pressure measurement port may also be sited at any point along the fuel circuit, including the fuel rail if this is made, at least partly, from a plastic material.

Claims

Claims 1. A fuel line arrangement for a motor vehicle, comprising a plastic material fuel conduit, a moulded diagnostic port integrated with the fuel conduit, the port comprising a housing having a pressure sampling valve, in which the housing has around an external periphery of the housing an annular latching feature.
2. A fuel line arrangement as claimed in Claim 1, in which the annular latching feature is a ridge on a cylindrical portion of the housing.
3. A fuel line arrangement as claimed in Claim 1 or Claim 2, in which the housing has an aperture leading to the valve, the valve having inside the aperture a plunger which may be moved to open the valve by a pin inserted into the aperture.
4. A fuel line pressure measurement apparatus, comprising a fuel line arrangement as claimed in any preceding claim, and means for making a fuel pressure measurement, said means including a connector that has a latch mechanism for engaging with the latch feature when a pressure-tight connection is made between the port and the connector.
5. A fuel line pressure measurement apparatus as claimed in Claim 4, in which the connector is latched to the port in a press-fit engagement.
6. A fuel line pressure measurement apparatus as claimed in Claim 4 or Claim 5, in which sealing means is provided between the connector and the port, said sealing means making a pressure-tight seal before or as the connector is latched to the port.
7. A fuel line pressure measurement apparatus as claimed in any one of Claims 4 to 6, in which the connector has a cylindrical body portion, with a pair of axially spaced o-ring seals, said seals making a pressure-tight fit with an external surface of the housing prior to the engagement between the latch mechanism and the latch feature.
8. A fuel line pressure measurement apparatus as claimed in any one of Claims 4 to 7, in which the connector has a body which is moulded.
9. A fuel line pressure measurement apparatus as claimed in any one of Claims 4 to 8, in which the connector has around an external periphery of the connector an annular ridge, and the latching mechanism is a hollow ring that is retained on the connector by the ridge, and which has an engagement feature that latches with the latching feature.
10. A fuel line pressure measurement apparatus as claimed in Claim 9, in which the ring has a generally cylindrical body with a radially inward directed lip at one end of the body that retains the ring on the ridge, and at the other end of the body one or more radially inward directed detents that act as the engagement feature.
11. A fuel line pressure measurement apparatus as claimed in Claim 10, in which there are a pair of detents which oppose each other across the hollow of the ring, the ring being flexible so that the ring may be deformed to increase the separation between the detents to aid latching or unlatching of the detents from the latching feature.
12. A fuel line pressure measurement apparatus as claimed in Claim 11, in which the detents and the latching feature have surfaces which cooperate to expand the separation between the detents when the ring is pressed axially to the latching feature.
13. A fuel line arrangement for a motor vehicle substantially as herein described, with reference to or as shown in the accompanying drawings.
14. A fuel line pressure measurement apparatus substantially as herein described, with reference to or as shown in the accompanying drawings.