Fluid level detector

Abstract

A fluid detector for determining a presence of a fluid within a container having a wall with an outer surface includes a piezoelectric element that outputs a first ultrasonic signal in response to an input electrical signal and a lens with an upper portion and a lower portion. A generally cylindrical wall is integral with and extends outwardly from the outer surface of the wall of the container and defines a cylindrical central bore having a base surface. The piezoelectric element is coupled to the upper portion of the lens so that, when the lens is disposed within the cylindrical central bore adjacent the base surface, the lens focuses the first ultrasonic signal toward the wall so that the first ultrasonic signal enters the wall. The fluid detector also includes an ultrasonic detector that, when disposed in a predetermined position adjacent the outer surface of the wall, receives a second ultrasonic signal from the wall that results from the first ultrasonic signal and that is affected in a predetermined manner by presence or absence of fluid at an inner surface of the wall. The ultrasonic detector generates an output electrical signal corresponding to the second ultrasonic signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the fluid level detector, including the best mode thereof to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the accompanying figures, in which;

FIG. 1 is an exploded, perspective view of a fluid level detector in accordance with an embodiment of the present disclosure;

FIG. 2 is a side view of the assembled fluid level detector as shown in FIG. 1;

FIG. 3 is a bottom view of the assembled fluid level detector as shown in FIG. 1;

FIG. 4A is an exploded, perspective view of a sensor assembly of the level detector as shown in FIG. 1;

FIG. 4B is a top perspective view of the assembled sensor assembly as shown in FIG. 4A;

FIG. 5A is a side, cross-sectional view of the sensor assembly as shown in FIG. 4B, taken along line 5A-5A;

FIG. 5B is a side, cross-sectional view of the sensor assembly as shown in FIG. 4B, taken along line 5B-5B;

FIG. 6 is a detailed, partial cross-sectional view of the sensor assembly as shown in FIG. 5B;

FIG. 7A is a side, cross-sectional view of the fluid level detector as shown in FIG. 3, along line 7A-7A;

FIG. 7B is a side, cross-sectional view of the fluid level detector as shown in FIG. 7A, positioned adjacent a container wall;

FIG. 8 is an exploded, perspective view of a fluid level detector in accordance with an embodiment of the present invention;

FIG. 9 is an exploded, side cross-sectional view of the fluid level detector as shown in FIG. 8;

FIG. 10 is a side, cross-sectional view of the fluid level detector as shown in FIG. 8;

FIGS. 11A through 11C are front, side and back views of a printed circuit board with electrical connectors as shown in FIG. 8;

FIG. 12 is a side, cross-sectional view of a fluid level detector in accordance with an embodiment of the present invention;

FIGS. 13A and 13B are an electrical schematic of an electronic module for use with a fluid level detector as shown in FIG. 1;

FIGS. 14A and 14B are an electrical schematic of an excitation circuit for use in an electronic module as shown in FIGS. 13A and 13B; and

FIGS. 15A and 15B are graphical representations of signals processed by the electronic module as shown in FIGS. 13A and 13B and 14A and 14B.

Claims

1. A fluid detector for determining a presence of a fluid within a container having a wall with an outer surface and an inner surface, the fluid detector comprising: a piezoelectric element that outputs a first ultrasonic signal in response to an input electrical signal;a lens with an upper portion and a lower portion;a generally cylindrical wall being integral with and extending outwardly from the outer surface of the wall of the container, the generally cylindrical wall defining a cylindrical central bore having a base surface adjacent the outer surface of the wall of the container; andwherein the piezoelectric element is coupled to the upper portion of the lens so that, when the lens is disposed within the cylindrical central bore adjacent the base surface such that the lens is intermediate the piezoelectric element and the wall, the lens focuses the first ultrasonic signal toward the wall so that the first ultrasonic signal enters the wall; andan ultrasonic detector that, when disposed in a predetermined position adjacent the outer surface of the wall, receives a second ultrasonic signal from the wall that results from the first ultrasonic signal and that is affected in a predetermined manner by presence or absence of fluid at the inner surface of the wall, wherein the ultrasonic detector generates an output electrical signal corresponding to the second ultrasonic signal.

2. The fluid detector as in claim 1, wherein the piezoelectric element comprises a piezoelectric film.

3. The fluid detector as in claim 2, wherein the ultrasonic detector is comprised of the piezoelectric element and the lens and the predetermined position is within the cylindrical central bore of the container.

4. The fluid detector as in claim 3, wherein the base surface of the cylindrical central bore is coplanar with the outer surface of the wall of the container.

5. The fluid detector as in claim 3, wherein the cylindrical central bore extends into the wall of the container such that the base surface of the cylindrical central bore is disposed between the outer surface and the inner surface of the wall of the container.

6. The fluid detector as in claim 5, wherein the outer surface of the wall of the container from which the generally cylindrical wall extends is curved.

7. The fluid detector as in claim 6, wherein the base surface of the generally cylindrical bore is planar.

8. The fluid detector as in claim 3, further comprising a top housing including a generally cylindrical inner wall that is configured to slidably receive the generally cylindrical wall of the container.

9. The fluid detector as in claim 8, further comprising: a retention pin extending axially from an outer peripheral surface of the generally cylindrical wall of the container; anda retention aperture defined by the top housing;wherein the retention aperture is configured to receive the retention pin in a friction fit such that the top housing is secured on the generally cylindrical wall of the container.

10. The fluid detector as in claim 8, further comprising: an annular groove formed in one of the generally cylindrical wall of the container and the generally cylindrical inner wall of the top housing; andan annular lip formed on an other of the generally cylindrical wall of the container and the generally cylindrical inner wall of the top housing;wherein the annular lip is configured to engage the annular groove such that the top housing is secured on the generally cylindrical wall of the container.

11. The fluid detector as in claim 3, wherein the piezoelectric film comprises a polyvinylidene fluoride copolymer.

12. The fluid detector as in claim 3, wherein the piezoelectric film, the lens and the wall of the container have substantially similar acoustic impedances.

13. The fluid detector as in claim 3, wherein the lens focuses the first ultrasonic signal on the inner surface of the wall.

14. A fluid detector for determining a presence of a fluid, the fluid detector comprising: a container with a wall with an outer surface and an inner surface, a portion of the wall extending outwardly from the outer surface of the wall and defining a cylindrical central bore with a base surface disposed proximal to the wall of the container;a piezoelectric element that outputs a first ultrasonic signal in response to an input electrical signal; anda lens with an upper portion and a lower portion;wherein the piezoelectric element is coupled to the upper portion of the lens so that, when the lens is disposed within the cylindrical central bore such that the lens is intermediate the piezoelectric element and the wall, the lens focuses the first ultrasonic signal toward the wall so that the first ultrasonic signal enters the wall; andan ultrasonic detector that, when disposed in a predetermined position adjacent the outer surface of the wall, receives a second ultrasonic signal from the wall that results from the first ultrasonic signal and that is affected in a predetermined manner by presence or absence of fluid at the inner surface of the wall, wherein the ultrasonic detector generates an output electrical signal corresponding to the second ultrasonic signal.

15. The fluid detector as in claim 14, wherein the base surface of the cylindrical central bore is recessed into the wall of the container.

16. The fluid detector as in claim 14, wherein the base surface of the cylindrical central bore is coplanar with the outer surface of the wall of the container.

17. The fluid detector as in claim 14, wherein the ultrasonic detector is comprised of the piezoelectric element and the lens and the predetermined position is within the cylindrical central bore of the container.

18. The fluid detector as in claim 14, further comprising a top housing including a generally cylindrical inner wall that is configured to slidably receive the portion of the wall of the container that defines the cylindrical central bore.

19. The fluid detector as in claim 18, further comprising: an electrical signal source; anda pair of spring contacts that are electrically conductive, wherein the pair of spring contacts are electrically coupled between the electrical signal source and the piezoelectric element so that the pair of spring contacts conducts the input electrical signal between the electrical signal source and the piezoelectric element, and wherein the pair of spring contacts are also disposed in the top housing in operative communication with the piezoelectric element so that, when the portion of the wall of the container that defines the cylindrical central bore is received within the top housing, the pair of spring contacts biases the piezoelectric element operatively toward the wall of the container so that the first ultrasonic signal is directed to the wall.

20. The fluid detector as in claim 18, further comprising: a retention pin extending axially from an outer peripheral surface of the portion of the wall of the container that defines the cylindrical central bore; anda retention aperture defined by the top housing;wherein the retention aperture is configured to receive the retention pin in a friction fit such that the top housing is secured on the generally cylindrical wall of the container.

21. The fluid detector as in claim 18, further comprising: an annular groove formed in one of the portion of the wall of the container that defines the cylindrical central bore and the generally cylindrical inner wall of the top housing; andan annular lip formed on an other of the portion of the wall of the container that defines the cylindrical central bore and the generally cylindrical inner wall of the top housing;wherein the annular lip is configured to engage the annular groove such that the top 7 housing is secured on the generally cylindrical wall of the container.

22. The fluid detector as in claim 14, wherein the piezoelectric element comprises a piezoelectric film.

23. The fluid detector as in claim 22, wherein the piezoelectric film comprises a polyvinylidene fluoride copolymer.