Connector for supplying diesel exhaust treatment fluid

Abstract

The invention relates to a connector for supplying a diesel exhaust treatment fluid in a system for reducing NOx of a diesel internal combustion engine, said connector (3; 16; 21) extending along a given axis (A) and comprising: an inner tube (4) made of metal and having a first outer surface (8) and a first inner surface (7) for conveying a diesel exhaust treatment fluid; and an outer tube (5; 17; 22) made of a polymer material and exposed to the environment along a given portion, the outer tube being shaped to form a gap (11; 18; 27) between the inner tube (4) and the outer tube (5; 17; 22) and axially extending at least along the given portion.

Description

Technical Field

[0001] The present invention relates to a connector for supplying diesel engine exhaust treatment fluid. Background Art

[0002] This connector is called Part of the hydraulic circuit of a system configured for reducing NOx produced by a diesel internal combustion engine and comprising a metering and dispensing unit for injecting a diesel exhaust fluid (DEF), typically a 32.5% urea solution in water, into the exhaust gas stream. Urea is converted into ammonia by pyrolysis and hydrolysis. In the catalytic converter, the ammonia reduces the nitrogen oxides to water and nitrogen. Emission regulations stipulate a maximum time for engine start-up, during which the system must be fully operational to reduce nitrogen oxides. The most stringent conditions of use are that the system must be started at an ambient temperature below -11°C, which corresponds to the freezing point of the diesel exhaust fluid.

[0003] Known hydraulic connectors are the most critical parts of the hydraulic circuit of DEF, as they are partially exposed to the external temperature. The connectors include a metal tube and a plastic sheath molded onto the metal tube, and are configured to be heated to thaw the DEF before activating the pump unit to supply the DEF. The connectors can be heated by wires outside the tube or embedded in the connector, or by a heating system located inside the connector and based on high resistance technology (e.g. PTC with a sharp metal plate as a diffuser).

[0004] A problem with known connectors is that the amount of heat that can be transferred to the hydraulic connector is limited. Due to design constraints on the overall size of the system, the connector must be located away from the core of the heating source.

[0005] Currently available solutions are inefficient due to the large amount of energy required to achieve the defrosting requirement and are unreliable due to rapid aging of the plastic due to overheating to compensate for heat losses. Summary of the invention

[0006] An object of the present invention is to provide a connector which can eliminate or at least alleviate the disadvantages of the known technology.

[0007] According to the present invention, there is provided a connector for supplying a diesel exhaust treatment fluid in a system for reducing NOx of a diesel internal combustion engine, the connector extending along a given axis and comprising: an inner tube, the inner tube being made of metal and having a first outer surface and a first inner surface for conveying the diesel exhaust treatment fluid; and an outer tube, the outer tube being made of a polymer material and being exposed to the surrounding environment along a given portion, the outer tube being formed to form a gap, the gap extending radially between the inner tube and the outer tube and extending axially at least along the given portion.

[0008] The gap formed along the exposed portion improves thermal insulation, prevents diesel exhaust fluid trapped inside the connector from freezing, and reduces thawing time to achieve customer-required dosage.

[0009] In particular, the gap is formed completely in the outer tube.

[0010] In particular, the outer tube includes a first tubular portion adhered to the inner tube and a second tubular portion radially spaced apart from the first tubular portion.

[0011] In this way, the entire inner metal tube is sheathed and in close contact with the outer tube.

[0012] According to various embodiments, the gap is delimited by an outer surface of the inner tube and the outer tube.

[0013] According to the present invention, the connector includes an insulating layer received in the gap for further enhancing the insulating performance of the connector.

[0014] In particular, the gap comprises an open end, and the insulating layer is made by injecting / spraying insulating foam into the gap through the open end.

[0015] This is particularly useful considering that the gap is quite narrow and is between 1-1.5 mm when measured radially.

[0016] According to one embodiment of the invention, the gap is greater than 2 mm when measured in the radial direction. In this configuration, the gap may not be filled with insulating material, and the outer tube has the function of a protective shield. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Other features and advantages of the present invention will become more apparent from the following description of non-limiting embodiments of the present invention with reference to the accompanying drawings, in which:

[0018] - Figure 1 shows a front view of a system for reducing NOx in a diesel internal combustion engine according to the present invention, with portions removed and portions in cross-section for clarity;

[0019] - Figure 2 and Figure 3 The first embodiment of the present invention is shown. Figure 1 a cross-sectional view of a connector of the system, with portions removed for clarity;

[0020] - Figure 4 and Figure 5 shows a cross-sectional view of a connector according to a second embodiment of the present invention, with parts removed for clarity; and

[0021] - Figure 6Shown is a cross-sectional perspective view of a connector according to a third embodiment of the present invention, with parts removed for clarity. DETAILED DESCRIPTION

[0022] Figure 1 A system for reducing NOx of a diesel internal combustion engine (not shown) is shown, the system comprising a diesel exhaust treatment fluid metering and dispensing unit 1; a catalytic converter 2; and a connector 3, the connector connecting the diesel exhaust treatment fluid metering and dispensing unit 1 to the catalytic converter 2 and supplying the diesel exhaust treatment fluid from the metering and dispensing unit 1 to the catalytic converter 2 when in use. The connector 3 extends along a longitudinal axis A and comprises an inner tube 4 and an outer tube 5, the outer tube 5 surrounding the inner tube 4 and provided with a flange 6 for fixing the connector 3 to the diesel exhaust treatment fluid metering and dispensing unit 1. The portion of the connector 3 extending between the diesel exhaust treatment fluid metering and dispensing unit 1 and the catalytic converter 2 is exposed to air and ambient temperature.

[0023] Reference Figure 2 , the inner tube 4 is made of metal and has an inner surface 7 and an outer surface 8, while the outer tube 5 is made of a polymer material and has an inner surface 9 and an outer surface 10. The outer tube 5 is formed to form a gap 11, which extends between the inner tube 4 and the outer surface 10 of the outer tube 5 at least along the portion exposed to the air and surrounds the inner tube 4. The size of the gap 11 in the diameter direction is in the range of 1-1.5 mm.

[0024] The gap 11 is tubular and is completely formed in the outer tube 5, which includes a tubular portion 12 adhered to the inner tube 4 over the entire length of the inner tube 4 and a tubular portion 13 radially spaced from the tubular portion 12. The gap 11 formed therein has an open end 14 at one end of the connector 3.

[0025] Reference Figure 3 , the connector 3 includes an insulating layer 15 accommodated in the gap 11 , and the insulating layer 15 is formed by injecting / spraying insulating foam into the gap 11 from the open end 14 .

[0026] During use, the connector 3 can be heated because the inner tube 4 is made of metal and the inner surface 7 of the inner tube 4 is well insulated from the outside to prevent freezing because the inner surface 7 of the inner tube 4 is separated from the outside by the wall of the inner tube 4, the tubular portion 12 of the outer tube 5, the insulating layer 15, and the tubular portion 13 of the outer tube 5 in sequence.

[0027] Reference Figure 4 The connector is denoted by reference numeral 16, which differs from the connector 3 in that the outer tube 17 is shaped to form a gap 18, which is defined by the outer surface 8 of the inner tube 4 and the outer tube 17, and is similar to the gap 11 ( Figure 2 and Figure 3 ) has an open end 19. The dimension of the gap 18 in the diameter direction is in the range of 1-1.5 mm.

[0028] Reference Figure 5 , the connector 16 includes an insulating layer 20 which is received in the gap 18 and formed by injecting / spraying insulating foam into the gap 18 from the open end 19 .

[0029] Reference Figure 6 The connector is indicated by reference numeral 21, and the connector includes an outer tube 22, the outer tube 22 includes a flange 23 transverse to the axis A, a tubular portion 24 adhered to the inner tube 4, and a tubular portion 25 spaced apart from the tubular portion 24 and connected to the tubular portion 24 by an annular shoulder structure 26, and the outer tube forms a gap 27 greater than 2 mm, the gap 27 extends along the axis and corresponds exactly to the portion of the connector 21 exposed to the air.

[0030] The gap 26 can be filled with an insulating layer or left empty. According to a second option, the tubular portion 25 serves as a protective shield.

[0031] Finally, it is obvious that modifications and further variations are possible on the subject matter of the invention described herein, without departing from the scope of protection of the appended claims. In particular, the described embodiments may be combined.

Claims

1. A connector for supplying a diesel exhaust treatment fluid in a system for reducing NOx in a diesel internal combustion engine, the connector (3; 16; 21) extending along a given axis (A) and comprising: An inner tube (4) made of metal and having a first outer surface (8) and a first inner surface (7) for conveying a diesel exhaust treatment fluid; and an outer tube (5; 17; 22) made of a polymer material and exposed to the environment along a given portion, the outer tube being formed to form a gap (11; 18; 27) extending radially between the inner tube (4) and the outer tube (5; 17; 22) and extending axially at least along the given portion.

2. The connector according to claim 1, wherein: The gap (11; 27) is formed completely in the outer tube (5; 22).

3. The connector according to claim 2, wherein: The outer tube (5; 22) comprises a first tubular portion (12; 24) adhered to the inner tube (4) and a second tubular portion (13; 25) radially spaced apart from the first tubular portion (12; 24).

4. The connector according to claim 1, wherein: The gap is delimited by the outer surface (8) of the inner tube (4) and the outer tube (17).

5. A connector according to any one of the preceding claims, wherein The connector comprises an insulating layer (15; 20) received in the gap (11; 18).

6. A connector according to any one of the preceding claims, wherein: The gap (11; 18) comprises an open end (14; 19), and the insulating layer (15; 20) is made by injecting / spraying insulating foam into the gap (11; 18) through the open end (14; 19).

7. A connector according to any one of the preceding claims, wherein: The gap (11; 18) is between 1 and 1.5 millimeters when measured in the radial direction.

8. The connector according to any one of claims 1 to 7, wherein: When measured in the radial direction, the gap (27) is greater than 2 mm.

9. A system for reducing NOx of a diesel internal combustion engine, said system comprising a connector (3; 16; 21) according to any one of the preceding claims.

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