MXPA00004349A - Liquid level gauge - Google Patents

Abstract

A liquid level gauge (10) utilizes a liquid tight plastic envelope (44) carrying an alongate p-c board (48) that has a light source (52) mounted so as to direct light laterally thereof, and a light sensor (54) also mounted so as to receive light from a direction which is lateral of the board. The gauge further has a lens configuration (45) which is part of the envelope, for providing a largely solid, reflective path for light which emanates at the light source and is to be received at the light sensor. When the exterior of the envelope is surrounded by either air or liquid, changes in the amount of light that is reflected by the lens occur, and are measured by the light sensor (54).

Description

LIQUID LEVEL CALIBRATOR Technical Field The present invention relates to Liquid Level Gauges, and more particularly to gauges of the electronic type using immobile parts.

BACKGROUND OF THE INVENTION More particularly, the present invention relates to improvements made to the calibrator described in US Pat. No. 4,840,137 dated June 20, 1989, entitled "LIQUID LEVEL CALIBRATOR APPARATUS", which belongs to the same authors as the present application. The complete description of the North American patent No. 4,840,137 is incorporated in the present application, as a specific reference. U.S. Patent No. 4,840,137, identified above, illustrates and describes a liquid level calibrator, with a semi-transparent cup-shaped body with a closed terminal, the terminal is configured in such a way that it is a refractive light prism. A light source and a light sensor are mounted inside the body. In the described embodiment, both the source and the sensor are secured in operative positions by a conveyor block (72). This last part has seats for the source and the sensor, so that they are positioned so as to be slightly in convergence with respect to each other. Essentially, the calibrator detects variations in the light that is reflected on the inside of the lenses, when they are immersed in liquids. Changes in the light that reaches the sensor are converted into liquid level measurements in the outer area of the lenses.

With the described design, high resolution measurements are relatively possible. Due to the space requirements and the restrictions of the automotive vehicle manufacturers, after the presentation of said request, adjustments were made to the same, which were achieved in this patent, the design described was modified to incorporate an internal extension of the printed circuit board containing the different electrical circuits, which were necessary to supply power to the light source, as well as to process the output of the light sensor. As a consequence of these modifications, one proposal was the assembly of the light source and the light sensor on a miniature printed circuit board, which was placed perpendicular to the main printed circuit board. However, it was presented a different disadvantage, that resides in the assembly of the miniature circuit board, and the establishment of the electrical connections between the miniature board and the main one, the elongated printed circuit board. In addition, in cases where the calibrator was subjected to vibration, as in automotive applications, it must have a reliable operation and for long periods of use. A fairly concise explanation of the operation theory of the calibrators of the type to which the present invention refers is provided in US Patent No. 4,998,002 issued March 5, 1991, entitled OPTICAL LIQUID LEVEL SENSOR USING A PERFLUOROALKOXI MATERIAL. POLITETRAFLUORUROETHYLENE, granted to Conax Buffalo Corporation, Buffalo, New York. Of which specific reference was made on the first page of the drawings of this patent, and the description beginning on line 10, col. 6 of it. The complete description of the North American patent No. 4,998,002 is also incorporated in the present application as a specific reference.

SUMMARY OF THE INVENTION The aforementioned disadvantages in patented calibrators, and other reflex type calibrators in general, are solved in an important way by the present invention, which has as its purpose, the provision of a new and improved liquid level calibrator that is Simple construction and reliable operation. Another purpose of the present invention is to provide an improved liquid level calibrator., as established above, which is more easily assembled and its manufacture is less expensive, since it lends itself to mass production techniques. An objective related to the present invention is to provide an improved liquid level calibrator according to the above, wherein the different components are protected against inadvertent contact with the liquid being calibrated, and it is also resistant to vibration, resulting in in a calibrator with a long life expectancy. Yet, another purpose of the present invention is to provide an improved liquid level calibrator as described above, which is especially versatile, and which does not require adjustments after initial assembly.

Yet another object of the invention is to provide an improved liquid level calibrator, as set forth above, in which the light sensor and the light source, as well as the electrical circuit system that accompanies them , they are all contained safely in a sealed cover. Yet another additional object of the present invention is to provide an improved liquid level gauge of the indicated type, in which its installation in a tank or tank has been simplified, and does not require special tools or attachments. For the realization of the aforementioned objects of the present invention, a device is provided which responds to obtain a predetermined height of the liquid in a container, which comprises the combination of the elongated printed circuit board which has a system of electrical circuits , a light source mounted on a terminal of the printed circuit board to direct light laterally thereto, the light source being connected to the circuitry of the board, and the light response means also connected to a light source. of the terminals of the printed circuit board, to receive the light that is directed laterally to the panel board. The light response means are also connected to the circuitry of the board. Additionally, an elongated tight plastic wrap enclosing the printed circuit board is provided, and the lens means containing the cover to provide a reflection path, largely solid for light emanating from the source and received in the media. of light response. The lens means have the ability to assist in the establishment of the trajectory, on the outside of the cover, which deviates from the solid reflecting path when the exterior of the cover is surrounded by liquid having a reflection index that it is different from the reflection index of the lens means. The positioning of the elements is done in such a way that the light source and the light response means can be mounted directly on the printed circuit board, in a lateral direction, together with the other components and without the necessity of "focus" on any of the components towards the lens media. In this way the assembly is achieved significantly easier and improved operating reliability. Next, other features and advantages of the present invention can be found.

BRIEF DESCRIPTION OF THE DRAWINGS The following drawings illustrate a preferred embodiment of the present invention: Figure 1 is a sectional view of the axis of the liquid gauge of the present invention, comprising the gauge, a cover and an internal printed circuit board , and being adapted to monitor the level of liquid contained in a container, such as a gasoline tank, an oil saucer, or another reservoir containing other liquids, for example, from a motor vehicle. Figure 2 is a section of the caliper shaft of Figure 1, taken at the right angle thereof. Figure 3 is a plan view of the printed circuit board used in the gauge of Figures 1 and 2, Figure 4 is a left end view of the gauge of Figures 1 and 2; and Figure 5 is a diagrammatic representation of the lens means of the caliper cover, showing the trajectories of a ray of light that is largely reflected internally within the lens means by themselves.

Detailed Description of the Invention Figures 1 and 2 illustrate the liquid calibrator for detecting the presence or absence of liquid at a predetermined level in a tank or container. The calibrator is generally designated by the number 10. In several aspects, the mounting structure of the present construction of the liquid calibrator is similar to that shown in the application of US Patent No. 4., 840,137 previously identified. In particular, a tubular metal fitting 12 is provided having a body, a hexagonal head 16 and threaded screws 18, to enable the fitting 12 to be inserted into a threaded hole (not shown) of the container with which, the Calibrator will be used. To achieve the seal with the threaded hole wall, an elastic seal ring 20 of rectangular cross-section and an elastic O-ring 22 are provided, both can be of conventional construction. The fitting 12 carries a molded plastic electrical connector or end block 24 having a transverse wall 26 with three holes for accommodating the three male electrical terminals or tips 28, 30 and 32, to be connected to the circuit board that will be described below . The connector block 24 has a cup-shaped recess 34, Figure 3, and an oval flange 36 into which the tips 28-32 are placed for connection to an electrical connector and the associated wiring fittings of a vehicle. automotive (not shown). The accessory 12 has an external flange 38, which is placed on a shoulder 40 of a connector block 24 as illustrated in order to permanently hold it. A seal between the accessory 12 and the connector block 24 is provided by an additional O-ring 42. In accordance with the present invention, a new and improved plastic wrap is provided in the form of an elongated liquid liner, a hollow tube or tubular shell 44 and the one-piece multi-sided lens means 45, for producing a largely solid trajectory, a reflecting path for the light generated internally from the cover, and assisting in the establishment of a light path, on the outside of the cover 44, which deviates from a predetermined refractive light path internally only at those times when the cover 44 is surrounded by the liquid. In a typical case, the reflection index of the liquid is different from the reflection index of the plastic of which the cover 44 is constituted. The lens means 45 has the shape of a conical prism 46, as illustrated. The elongated cover and the elongated printed circuit board generally have a common axis with one another. With reference to Figures 1 and 2, an elongated printed circuit board 48 having the electrical circuit 50 shown dramatically with the dotted underline in Figure 1, which is part of the electrical circuit system 50 comprising a light source and a light sensor, is mounted on the cover similar to a tube 44, coincident with the axis thereof. In a preferred application and as shown in the figures, the light source is in the form of a light emitting diode 52, and the light sensor comprises a phototransistor 54, preferably one of the Darlington type to improve its sensitivity. The printed circuit board has a midline, with both the light-emitting diode 52, the phototransistor 54 and the terminal or tip of the printed circuit board 48 being placed on the middle line. In addition, according to the present invention, the light-emitting diode 52 and the phototransistor 54, are mounted directly to the printed circuit board 48, and are juxtaposed with each other, with the light-emitting diode 52 oriented in a lateral direction of the board 48, preferably in a perpendicular manner thereto, and the phototransistor 54 oriented in an opposite lateral direction of the board 48, and being also preferably perpendicular thereto. The lens means 45, includes a plurality of prism surfaces, generally designated with the numbers 56, 58, 60, 62, 64 and 66. One surface 46 is placed directly opposite the light emitting diode 52, and another surface 66 is placed directly in front of the phototransistor 54 when the printed circuit board 48 is secured in position within the cover 44, as illustrated in Figures 1 and 2. The distribution is such that a light beam indicated by the arrows in Figure 5 and emanating from the light emitting diode 52 can pass into the interior of the light receiving surface. 56 adjacent and will be internally reflected outward from the surface 58, so that it reaches the surface 60. There, depending on whether or not the cover 44 is immersed in liquid, the beam will also pass further as an additional reflection in the direction to the surface 62, or otherwise, it will be deflected through the lens means 45 or the prism 46, and will exit through the surface 60 and pass through the liquid. Under this last condition, the trajectory of the ray of light deviates from what would otherwise be a solid reflex trajectory, which places it completely within the lens means. On the other hand, in the absence of liquid at the surface 60, the reflected beam will experience another reflection through the surface of the prism 62. This reflection will result in the beam being directed towards the surface 64, internally through the cover plastic, towards the surface 64 for the light transmitting surface 66, from a perpendicular direction, and will pass through the surface 66, to be picked up by the phototransistor 54. Under such circumstance, the path for the light beam is essentially a through the solid plastic material of the cover 44 and the lens means 45. An electrical conduction condition of the phototransistor 54 will result in a signal indicating that the cover 44 is not immersed in the liquid. The electronics used with both the light emitting diode 52 and the phototransistor 54 can take various forms. The three contact tips 28, 30 and 32 provide electrical connections to the printed circuit board 48 from the vehicle wiring harness (not shown). The printed circuit board 48 also has a number of electrically active and passive components (not shown) used to cause the light emitting diode 52 and to process the output from the phototransistor 54, these components were omitted from FIGS. 3, for purposes of clarity. Further, in the present invention cushioned or cushioned mounting means are provided between the remote terminal of the printed circuit board 48 and the cover 44 comprising an O-ring 68. In a preferred embodiment, the terminal of the printed circuit board 48 has a tip portion 70 with a head or extension forming a handle 72 and ring O 68 conforms to the extension and occupies the handle 72. The interior of the terminal of the cover 44 has a cylindrical cavity 74, and by the present invention , constitutes a tight fit with the O-ring 68. The positioning is made in such a way that the printed circuit board 48 is safely supported, resistant to impacts or vibration. The desired central positioning of the printed circuit board 48 is automatically effected by the elastic gear of the O-ring 68 with the cylindrical inner surface 74 of the terminal of the cover 44. The O-ring thus provides, not only a damped mounting for the printed circuit board, but also contributes to sliding placement between the portion of the tip 70 of the printed circuit board and the cylindrical inner surface of the cover. The cover 44 is received telescopically in the fitting 12 and the ring O 42 is previously perceived, it also provides a seal with the cover 44. Figure 1 shows a layer of epoxy sealer 76, which has been applied to the transverse wall 26 adjacent to the the tips from 28 to 32, to seal the holes through which it extends.

The described arrangement comprising the placement of the light emitting diode 52 and the phototransistor 54 has a distinct advantage over previous calibrators, most of which used a remotely located light source and a remotely located light sensor. Due to the current lateral placement of the light emitting diode and phototransistor 54, the above problems with the assembly of said components are completely solved, since the components lie flat against the printed circuit board, together with the other electrically active components and passive. In this way, we did not encounter problems in establishing electrical connections to them, unlike the placement used in the device of the previously identified US Patent No. 4,840,137, where a separate support block will be used to guide the channels components 56 and 62, shown in Figure 1 of that patent. In practice, the board 48 is secured to the cover 44, in such a way that the board and the cover will have the relative positions shown, this being necessary for the alignment of the surfaces of the prism from 56 to 66 with the light-emitting diode 52 and the phototransistor 54, as well as for the alignment of the printed circuit board 48 with the tips 28 to 32. From the foregoing, it can be appreciated that a new and improved liquid level calibrator has been provided which is simple in structure and of reliable use. The jump assembly of the light emitting diode 52 and the phototransistor 54 in the board 48 simplify their assembly. The terminal support of the printed circuit board 48 as provided by the O-ring 68 also facilitates its assembly; It is important that this terminal does not move or vibrate during use and that the O 68 ring effectively minimizes the possibility that this may occur. The calibrator as described, is made in this manner to represent a clear advantage and improvement in the field of liquid level calibrators. It is possible to make variations and modifications without departing from the spirit of the present invention.

Each and every one of the appended claims define an aspect of the present invention, which is separate and distinguishes it from all others, and consequently, it is intended that each claim be treated in this manner when examined in the light of the articles. of prior art in any determination of novelty or validity.

Claims (27)

R E I V I N D I C A C I O N S Having described the present invention, the content of the following CLAIMS is considered as a novelty and, therefore, claimed as property:

1. A device that responds to the ability to predetermine the amount of liquid in a container, which comprises, in combination: an elongated printed circuit board which contains a system of electrical circuits therein; a light source mounted on a terminal of the printed circuit board for directing light laterally therefrom, said light source being connected to the circuitry of the board; light response means mounted to said terminal of the printed circuit board, to receive the light that is directed laterally to the board thereof, said light response means being also connected to the circuitry of the board; an elongated cover adjusted against the liquids enclosing the printed circuit board, and lens means carried by said cover to provide a greatly solid reflection path for the light emanating from said source and which will be received in said light response means . said lens means having the ability to assist in the establishment, on the outside of said cover, of a trajectory that deviates from said solid reflection path when said exterior of the cover is surrounded by liquid, which has a reflection index which is different from the reflection index of the lens means.

2. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 1, further characterized in that there are means that provide a sliding fit between a terminal of the printed circuit board and a terminal of said cover.

3. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 1, further characterized in that, in said device, there are cooperative means which provide an assembly respectively between the other terminal of the device. printed circuit board and cover.

4. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 2, further characterized in that, in said device there are buffer means between the printed circuit board and the cover in said sliding installation.

5. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 4, further characterized in that there exist in said device damping means which comprise an elastic O-ring.

6. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 5, further characterized in that said O-ring is carried by said terminal of the printed circuit board.

7. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 2, further characterized in that said lens means comprises a one-piece multi-faceted structure that transmits light that it has an axis, and it has a cavity which is located on said axis and which receives said terminal of the printed circuit board.

8. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 1, further characterized in that, the light source and the light response means are located on a midline which it extends between the ends of the elongated circuit board.

9. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 1, further characterized in that the printed circuit board has a tip in said terminal and said light source is located between said tip and the light response means.

10. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 2, further characterized in that said cover comprises a plastic tube having a "closed end which comprises said positioning by sliding.

11. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 2, further characterized in that the cover comprises a light-transmitting plastic tube having a closed terminal, which comprises said lens means.

12. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 11, further characterized in that the lens means comprises a conical outer surface at the end of the plastic tube.

13. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 12, further characterized in that the lens means includes pairs of prism surfaces inside the cover, placed on surfaces opposite interiors of it.

14. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 13, further characterized in that, a surface of a pair of prism surfaces is oriented to said light source and a The surface of another pair of prism surfaces is oriented to said light response means.

15. A device which responds to obtaining a predetermined height of liquid in a container, as described in Claim 14, further characterized in that other surfaces of the pairs of prism surfaces are arranged angularly respectively with respect to the previously named surfaces of the pairs of prism surfaces.

16. A liquid level calibrator, which comprises, in combination: a hollow tube having a closed terminal for immersion in the liquid; a generally flat circuit board placed within said tube, and carrying a light source oriented in a direction away from one side of said board, and carrying a light sensor oriented in a direction away from the opposite side of the board; and a prism means in the closed terminal, to receive light from said light source and reflect it internally through the light sensor when the closed end of the hollow tube is not submerged in liquid, said prism means attenuating the light received in the light sensor according to the closed terminal of the tube is immersed in said liquid.

17. A liquid level calibrator, as described in the Claim 16, further characterized in that said prism has a light receiving surface, positioned adjacent to the light source, and a light transmitting surface positioned adjacent to the light sensor.

18. A liquid level gauge, as described in Claim 17, further characterized in that said light receiving and light transmitting surfaces are substantially parallel one with respect to the other, and placed on opposite sides of the circuit board.

19. A liquid level calibrator, as described in Claim 17, further characterized in that said light receiving surface is positioned substantially in the path of the light emitted by said light source.

20. A liquid level calibrator, as described in Claim 17, further characterized in that said light transmitting surface is positioned immediately adjacent to said light sensor.

21. A liquid level gauge, as described in Claim 16, further characterized in that, the light receiving surface is substantially also flat with respect to the plane of the circuit board.

22. A liquid level calibrator, as described in Claim 16, further characterized in that, the light transmitting surface is substantially also flat with respect to the plane of the circuit board.

23. A liquid level calibrator, as described in Claim 16, further characterized in that the light source and the light sensor are axially spaced from one another on the circuit board.

24. A liquid level calibrator, as described in Claim 16, further characterized in that both the light source and the light sensor are axially spaced from the closed end of the hollow tube, and are axially spaced from one another.

25. A liquid level calibrator, as described in Claim 16, further characterized in that the end of the hollow tube has a generally conical configuration of the outer surface.

26. A liquid level calibrator, as described in Claim 25, further characterized in that the configuration of the conical surface has an axis, and wherein the light receiving surface and the light transmitting surface are both substantially parallel to said axis.

27. A liquid level gauge, as described in Claim 16, further characterized in that it additionally includes elastic damping means placed in the hollow tube at its closed end and which fit the circuit board, so as to centralize the latter in The tube.