Level sensor assembly

Abstract

A level sensor assembly (10) for measuring physical properties indicative of a quality of a urea solution (AdBlue/DEF), where at least a portion of said level sensor assembly (10) is inserted in a tank (50), said level sensor assembly (10) comprises a header unit (12) mounted in an aperture of the tank (50); heating tubes (20) inserted in the tank for heating/thawing the urea solution in the tank (50) and one or more tubes (22) for suction of urea solution from the tank (50), said tubes (20,22) being connected to the header unit (12); and a level sensor (24,26) for measuring level of urea solution in the tank (50). Further, a detachable UQS sensor (30) is installed in the header unit (12), said UQS sensor (30) being at least partly submerged in a liquid pool (32) of urea solution in the header unit (12), and the liquid pool (32) in the header unit (12) comprises a compressible and/or expanding bottom (34).

Claims

1. A level sensor assembly for measuring physical properties indicative of a quality of a urea solution, where at least a portion of said level sensor assembly is inserted in a tank, said level sensor assembly comprises: a header unit mounted in an aperture of the tank, heating tubes inserted in the tank for heating or thawing the urea solution in the tank and one or more tubes for suction of urea solution from the tank, said tubes being connected to the header unit, and a level sensor for measuring level of urea solution in the tank, a detachable urea quality sensor is installed in the header unit, said urea quality sensor being at least partly submerged in a liquid pool of urea solution in the header unit, wherein the liquid pool in the header unit comprises a compressible and/or expanding bottom.

2. The level sensor assembly according to claim 1, wherein the liquid pool in the header unit is a liquid pool of return urea solution to the tank.

3. The level sensor assembly according to claim 2, wherein the liquid pool in the header unit is connected to an inlet for return urea solution and an overflow discharge of urea solution from the liquid pool into the tank.

4. The level sensor assembly according to claim 1, wherein the bottom comprises one or more elastic cups made of elastic material, said elastic cups are expandable during formation of ice in the liquid pool and retractable when the ice melts.

5. The level sensor assembly according to claim 1, wherein the bottom comprises one or more elastic cups made of compressible material, said elastic cups are compressible during formation of ice in the liquid pool and expandable when the ice melts.

6. The level sensor assembly according to claim 1, wherein the liquid pool in the header unit comprises a drainage hole for drainage of urea solution into the tank.

7. The level sensor assembly according to claim 1, wherein the liquid pool in the header unit is a liquid pool of filling urea solution to the tank.

8. The level sensor assembly according to claim 1, wherein the liquid pool in the header unit is a liquid pool of urea solution to be feed to a Selective Catalytic Reduction system.

9. The level sensor assembly according to claim 1, wherein the compressible and/or expanding bottom comprises a spring.

10. The level sensor assembly according to claim 1, wherein the level sensor comprises a tube with reed switches, which are activated by a magnetic float.

Description

DESCRIPTION OF THE DIAGRAMS

(1) Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein:

(2) FIG. 1 shows in cross section an upper part and a head of a level sensor assembly according to the invention.

(3) FIG. 2 shows a perspective view of the upper part with the head of the level sensor assembly according to the invention.

(4) FIG. 3 shows example of a complete a level sensor assembly according to the invention mounted in a tank.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(5) FIG. 3 shows a typical AdBlue tank 50 equipped with a level sensor assembly 10 according to the invention, in where the level sensor assembly 10 is arranged for measuring physical properties indicative of a quality of a urea solution (AdBlue/DEF). The tank 50 further comprises an inlet or opening 52 for filling of the urea solution. At least a portion of said level sensor assembly 10 is inserted in the tank 50, and a header unit 12 of the level sensor assembly 10 is mounted in an aperture at the top of the tank 50 and extends out of the aperture. The header unit 12 is equipped with a connector 40 for forwarding signals for level measuring and a connector 42 for forwarding signals for AdBlue quality measuring. The level sensor assembly 10 is further connected to a SCR (Selective Catalytic Reduction) system of a vehicle.

(6) Design and material composition of header structure may vary from OEM to OEM.

(7) The level sensor assembly 10 further comprises in a known way heating tubes 20 inserted in the tank for heating or thawing the urea solution in the tank 50 and one or more tubes 22 for suction of urea solution from the tank 50, said tubes 20,22 being connected to the header unit 12. FIG. 2 shows an example of heating tubes 20 with coils, but many other designs are possible.

(8) The level sensor assembly 10 further comprises in a known way a level sensor for measuring level of urea solution in the tank 50, and which is connected to the connector 40 for forwarding signals for level measuring. The level sensor can comprise a tube 24 with REED switches or AMR technology, which is activated by a magnetic float 26. FIG. 2 shows such an example of a level sensor, but many other designs are possible.

(9) A main feature of the invention is that a detachable urea quality sensor 30, hereafter called UQS sensor, is installed in the header unit 12, wherein the UQS sensor 30 is being at least partly submerged in a pocket or liquid pool 32 of urea solution in the header unit 12. The UQS sensor 30 is inserted in an opening, by screwing or otherwise fastened, in the header unit 12 such that it is directly above and in contact with the liquid pool 32 of urea solution.

(10) The UQS sensor 30 can be a sensor using special optical techniques for detecting variances in urea concentration, for instance as small as +/−2%, and can operate at temperatures from for instance −10 C.° to +85 C°. The optical measurement principle is robust against dirt and moving fluids including gasoline, diesel or coolant. The sensor enables continuous measurement of AdBlue/DEF-quality (proportion of urea in the solution or wrong medium).

(11) The liquid pool 32 in the header unit 12 is normally a liquid pool of return urea solution (returning from the SCR system) to the tank 50, and has or is connected to an inlet 36 for return urea solution and an overflow discharge 38 of urea solution from the liquid pool 32 into the AdBlue tank 50.

(12) A typical AdBlue tank 50 is mounted on the outside of a vehicle, normally next to the fuel tank, and the urea solution is therefore subjected to ice formation and/or freezing. In case the urea solution freezes is thus preferable to equip the liquid pool 32 in the header unit 12 with a compressible and/or expanding bottom 34, thus allowing liquid expansion.

(13) The bottom 34 may additionally consist of a flexible material allowing expansion or compression and possibly whereas a spring or similar can be installed on the outside or inside of the flexible material ensuring fully retraction or extraction of the elastic material. Thus, the bottom 34 may comprise one or more elastic cups 34a,34b. The elastic cups 34a,34b are preferable made of elastic or compressible material, which when not affected goes back to its original form. The spring can be used as an extra means to ensure extraction or compression of the elastic cups 34a,34b back to the original form.

(14) As shown in FIG. 1 the elastic cups 34a,34b are placed upside down, i.e. with the bottom facing upward.

(15) In one embodiment the elastic cups 34a,34b are made of compressible material and are arranged to be compressed in case of formation of ice in the liquid pool 32 and to expand when the ice melts.

(16) However, in a second embodiment, the elastic cups 34a,34b are made of elastic material and are arranged to be expandable in case of formation of ice in the liquid 32 pool and to retract when the ice melts.

(17) The elastic material provides that the flexible bottom 34 expand to take into account the increased volume of the ice. If the material is compressed during icing, it will be the wall thickness or the compressible material in the liquid pool 32 that is compressed to provide extra space during icing.

(18) In addition to the overflow discharge 38, the liquid pool 32 in the header unit 12 can comprise a drainage hole (not shown) for drainage of urea solution into the AdBlue tank 50 when not in use. The overflow discharge 38 and the drainage hole can be combined or integrated with each other.

(19) In alternative embodiments (not shown) and if possible to maintain sufficient through flow of liquid, the liquid pool 32 in the header unit 12 can be a liquid pool of filling urea solution to the tank, i.e. that the inlet opening 52 of the tank 50 is connected to the header unit 12 or that the urea solution is poured into the tank through the header unit 12. It is also possible that the liquid pool 32 in the header unit 12 can be a liquid pool of urea solution to be feed to the SCR system, thus insuring the quality of the urea solution to the SCR system.