GB2051367A - Indicating liquid levels - Google Patents

Abstract

A level indicator for use in an aircraft fuel tank (12) comprises a stick (46) in a vertical tube (18) separating the fuel space (14) from a space for the stick (46). The stick (46) can be inserted from the bottom and carries a magnet (44) at its upper end which co-operates with a magnet (30) in a float (26) surrounding the tube (18). Thus once released from a fitting (24) at the bottom, the stick will be supported by the magnets (30 and 44) at a height corresponding to the liquid level in the tank, and that level can be read by marks (48) on the stick. The stick is thin and flexible to be capable of being stably vertical when supported from the bottom while yet being flexible enough to bend rather than break when struck by a transverse blow. <IMAGE>

Description

SPECIFICATION Tank gauge The invention relates generally to means for measuring the level of liquid in a tank and particularly to a measuring stick type of gauge element wherein there is access to the gauge element from the exterior of the tank but the element itself is not exposed to the contents of the tank, auxiliary means being provided to enable the operator to withdraw the gauge element to obtain a true indication of the liquid level. Gauge means embodying a tubular housing are mounted vertically in a tank with a movable gauge element therein and a float on the outside thereof together with means for holding the gauge element vertically with reference to the float.

It has been well known in the past to use solid substantially rigid but lightweight rods which are either tubular, square or rectangular. Such rods have been made of fibreglass or other lightweight plastics materials. A problem with such substantially rigid gauge members of the prior art has been the fragility of such members. In the rough handling that is sometimes accorded the gauges, the rods have been known to break and therefore require replacement.

In addition, the task of imprinting or otherwise adding indicia to an extended circular, square or rectangular rod has required special and expensive printing processes. Because of the odd shape, the indicia have generally been added through expensive and time-consuming silly screen processes. Conventional high speed printing techniques which have obvious cost and speed advantages have not generally been availabie.

According to the present invention, a liquid level gauge comprises a tubular housing arranged to be secured in a tank with its interior separated from the contents of the tank, a float mounted to be able to slide along the outside of the housing as the liquid level changes, magnetic means carried by the float, and a measuring stick which can be inserted in the housing, the two magnetic means being arranged to co-operate to support the stick at a height corresponding to the liquid level, the stick comprising a flat strip bearing graduation marks and being rigid enough to be capable of extending vertically without bending when supported from a lower end. Thus, the stick can be a flexible, tape-like member which can be made of plastic or other lightweight and flexible material, such as aluminium or even steel.This gauge would have unequal moments of inertia about the X-X and the Y-Y axes. So that the gauge member can be self-supporting in the vertical position, a slight curvature is imparted with the radius of curvature being in a direction orthogonal to the linear dimension of the gauge element.

However, if a flexible material were used, an elongated rectangular cross-section, the flexibility could be preserved while the faces of the gauge could be parallel.

In either embodiment, a rotary type printing process could be used to either print or emboss the indicia upon the gauge element. The resulting gauge which may be retrofitted into existing housing is then lightweight and not easily broken in rough handling.

So long as the gauge member is of a material that can be self-supporting in the vertical direction, the gauge can be mounted either at the "top" of the tank or at the "bottom" of a tank.

Naturally, the "bottom" installation permits a thinner, more flexible gauge since the member does not have to support itself against gravity but rather, is supported by gravity, However, for those applications where it is desired to mount the gauge in the "top" of the tank, it is only necessary that the gauge element be sufficiently strong to support its own weight in a vertical orientation without collapsing.

The invention includes a stick for a liquid level gauge adapted to be wholly contained within a tank, said stick carrying magnetic means for cooperatively engaging magnetic floating means for positioning said stick to represent fluid level, said stick comprising an elongated, flexible, tape-like member having measuring indicia on at least one face thereof, said member being sufficiently rigid to be self-supportiny vertically without bending when supported from a lower end, and this includes a measuring stick in or for a liquid level tank gauge which carries measuring indicia, said stick being capable of extending stably vertically when held at its lower end, but being sufficiently flexible to bend rather than break when struck transversely.

Referring to the drawings: FIGURE 1 is a cross sectional view of an aircraft wing with a tank having a gauge means embodying the invention mounted therein; FIGURE 2 is a fragmentary view of the extended gauge element according to a preferred embodiment of the present invention; FIGURE 3 is a cross section view of the gauge element of FIGURE 2 taken along the line 3-3 in the direction of the appended arrows, and FIGURES 4 and 5 are cross sections of alternative flexible gauge elements.

More particularly, describing the invention and referring first to FIGURE 1, there is shown an aircraft wing 10 in which a tank 12 is installed and shown in cross section. The tank 12 can be considered as capable of being closed and customarily containing a liquid 14. Gauge means 1 6 embodyingsthe invention is shown mounted in the tank 12.

The gauge means 16 includes generally an outer assembly or gauge housing 18 comprising a "lower" section 20 within the tank 12 and a portion 22 outside of the tank 12 and mounted in the wing 10; a gauge element or inner assembly 24 that is mounted in but movable vertically with respect to the housing 20; a float 26; and, as wili later be described, means for orienting the gauge element vertically with relation to the float 26.

At its outer or exterior portion 22, the housing 1 8 is mounted to the wing 10 and the movable gauge element 24 has a fitting 28 that seats in the outer portion 22 of housing 20 and secures the gauge with a quarter turn latch.

The float 26, which is designed to float upon the liquid 14 in the tank 12 and be guided by he housing 18, as it rises and falls, is generally annular in shape to receive the housing 1 8. The float 26 may have a hollow chamber within which an annular permanent magnet 30 is placed.

Alternatively, an assembly of individual magnets, as is known, may be employed.

A float support member, shown here as a resilient collar 32 rests on a shoulder 34 and is contained partially within the tubular section 24 to cushion and limit downward movement of the float 26 in the event the liquid 14 in the tank 12 should fall to a very low level.

The inner gauge element 24 is fitted with a cap 36 that includes a spring member 38 and an oring 40 together with quarter turn latching means 42 that co-operates with fitting 28 so that the inner gauge portion can be locked in place wholly within the housing. Upon turning the assembly for releasing the inner element, the gauge element 24 springs out sufficiently far to be grasped manually.

The inner gauge member 24 is fitted at its remote end with a magnetic element 44 that can co-operate with the float element 26 to magnetically link the two together. The gauge itself, in a preferred embodiment, is a thin flexible tape-like member 46 which is substantially selfsupporting. This can be accomplished by imparting a slight curvature or bow to the gauge member 46 so that it may be considered an eleongated section of a cylinder with a radius of curvature at right angles to the long dimension.

Referring now to Figures 2 and 3, indicia 48 may be imprinted or embossed on the gauge member 46 corresponding to the tank in which it is to be utilised. Obviously, if the tank were perfectly symmetridal, then the indicia 48 would be equally spaced. Alternatively, if the tank were not perfectly symmetrical, then the gauge could be calibrated to accurately reflect the quantity of liquid in the tank as a function of the liquid level.

Since the float 26 and its associated magnetic element 30 is positioned at the surface of the liquid 14, in operation, the gauge member 24 is unlatched and can be manually withdrawn until the magnetic members interact and become' attracted to each other. At this point, the gauge element 24 will be held in place by the magnetic forces and the volume of liquid 14 stored in the tank 12 can be read from the exposed indicia 48.

Turning next to Figure 4, in an alternative embodiment, the inner gauge element 24 may be made of a metal tape 50 similar to a measuring tape. Alternatively, it can be made of a flexible plastic material that can be self-supporting and yet flexible if subject to forces not in the axial direction. Thus the section can be oval as showri at 52 in FIGURE 5.

In any case the stick is capable of extending stably vertically when held at its lower end, but being sufficiently flexible to bend rather than break when struck transversely.

Claims (10)

1. A liquid level gauge comprising a tubular housing arranged to be secured in a tank with its interior separated from the contents of the tank, a float mounted to be able to slide along the outside of the housing as the liquid level changes, magnetic means carried by the float, and a measuring stick which can be inserted in the housing and carries magnetic means, the two magnetic means being arranged to co-operate to support the stick at a height corresponding to the liquid level, the stick comprising a flat strip bearing graduation marks and being rigid enough to be capable of extending vertically without bending when supported from a lower end.

2. A gauge as claimed in Claim 1 in which the stick is a strip of plastics material.

3. A gauge as claimed in Claim 1 in which the stick is a strip of metal.

4. A gauge as claimed in any preceding claim in which the stick is of arcuate cross section.

5. A gauge as claimed in any of Claims 1-3 in which the stick is of rectangular cross section.

6. A gauge as claimed in any preceding claim, in which the stick is of elliptical cross section.

7. A stick for a liquid level gauge adapted to be wholly contained within a tank said stick carrying magnetic means for co-operatively engageing magnetic floating means for poisitioning said stick to represent fluid level, said stick comprising an elongated, flexible, tape-like member having measuring indicia on at least one face thereof, said member being sufficiently rigid to be selfsupporting vertically without bending when supported from a lower end.

8. A stick as claimed in Claim 7 of metal or plastics material.

9. A stick as claimed in Claim 7 or Claim 8 of arcuate, or rectangular, or elliptical, cross-section.

10. In or for, a liquid level tank gauge, a measuring stick carrying measuring indicia, said stick being capable of extending stably vertically when held at its lower end, but being sufficiently flexible to bend rather than break when struck transversely.