Leak detecting device for detecting a leak in a container

• US 5,939,620 A
• Filed: 04/24/1998
• Issued: 08/17/1999
• Est. Priority Date: 04/24/1998
• Status: Expired due to Term

• Current Assignee: Plastipak Packaging Incorporated (Plastipak Holdings Incorporated)
• Original Assignee: Crown Cork & Seal Technologies Corporation (Crown Holdings Incorporated)
• Inventors: Strand, Edward J.
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): WIGGINS, JOHN DAVID
• Application Number:
  US09/066,517
• Time in Patent Office: 480 Days
• Field of Search: 73/49.2 T, 73/49.2 R, 73/45, 73/41, 73/40
• US Class Current: 73/49.2
• CPC Class Codes: G01M 3/32 for containers, e.g. radiators
• CPC Class Codes: G01M 3/3218 for flexible or elastic containers
• CPC Class Codes: G01M 3/3236 by monitoring the interior space of the containers

Abstract

A leak detection system determines whether a container has a leak or an aperture by attempting to draw a vacuum in the container and determining whether a vacuum has been created in the container. If a vacuum can be created in a container, this indicates that the container has a leak. Conversely if a vacuum cannot be created in the container, this indicates that the container does not have a leak. The leak detection system preferably includes a conveyor system for moving a container and a sensor for sensing the pressure in the interior of the container through an opening in the top of the container. While the sensor is sensing the pressure in the interior of the container, a vacuum pump pulls air from the region around the exterior of the container. If the container has an aperture, a vacuum will be created in the container and will be noted by the sensor. Conversely, if the container does not have an aperture, a vacuum will not be created within the container and the sensor will determine this by noting that the pressure of the container is above a predetermined pressure limit. This sensor determines that the container has an aperture by noting that the vacuum in the container is greater in magnitude than a predetermined pressure limit. The leak detection system of this invention may further include a reject assembly for rejecting a container that is detected by the sensor to have an aperture and a controller for controlling the reject assembly in response to signals from the sensor.

Claims

1. A system for detecting the presence of an unwanted aperture in a container that has an opening comprising:

a continuously moving air permeable conveyor for moving the container such that the container opening moves along a path;

a vacuum source in fluid communication with the conveyor for creating a negative pressure proximal to the air permeable conveyor; and

a pressure sensor, mounted proximal to the path of the container opening so that the sensor is placed in fluid communication with the container opening as the container opening moves along the path, said sensor being operative to detect a pressure decrease within the moving container if the vacuum source pulls air through said unwanted aperture when the conveyor moves the container proximal to the sensor, thereby determining if the container has an unwanted aperture by determining the pressure decrease in the container.

2. The system of claim 1, wherein the pressure sensor further comprises a probe that has a hollow bore that places the sensor in fluid communication with the container opening as the conveyor moves the container along the path.

3. The system of claim 1, wherein the conveyor comprises an air permeable belt.

4. The system of claim 3, wherein the vacuum source is disposed beneath the air permeable belt.

5. The system of claim 1, further comprising a reject assembly that is coupled to the pressure sensor and that is operative to reject the container if the sensor detects the pressure decrease.

6. The system of claim 5, further comprising a controller, coupled to the pressure sensor and the reject assembly, that is operative to control the reject assembly in response to the sensor.

7. The system of claim 1, wherein the container has a bottom comprising a plurality of feet.

8. The system of claim 1, further comprising a stationary sensor mounting block in which the sensor is disposed and wherein the conveyor moves the container so that the opening of the container moves beneath the sensor mounting block while moving on the conveyor.

9. The system of claim 8, wherein the sensor mounting block comprises a probe that places the pressure sensor in fluid communication with an interior of the container through the opening in the container when the container passes beneath the sensor.

10. A system for detecting the presence of an unwanted aperture in a container that has a top that has a desired opening and a bottom, comprising:

a continuously moving conveyor that is operative to continuously move the container so that the desired opening moves along a path, the conveyor comprising a continuously moving belt that has an air permeable surface for supporting the bottom of the container;

a stationary pressure sensor, mounted proximal to the path of the desired opening, the pressure sensor being placed in fluid communication with the desired opening as the opening passes proximal to the sensor and if the container has the unwanted aperture, the pressure sensor being operative to detect a decrease in pressure within the container when the sensor is placed in fluid communication with the desired opening and while the container is moving; and

a vacuum source, disposed in fluid communication with the air permeable surface and (i) being operative to create a negative pressure proximal to the air permeable surface and proximal to the container as the belt and the container pass proximal to the sensor and as the opening is placed in fluid communication with the pressure sensor and (ii) if the container has the unwanted aperture, being operative to pull air from within the container and through the unwanted aperture to create a decrease in pressure inside of the container that can be detected by the pressure sensor, when the container is placed in fluid communication with the pressure sensor and as the container is moving thereby determining if the container has an unwanted aperture by determining the pressure decrease in the container.

11. The system of claim 10, wherein the vacuum source comprises a vacuum pump.

12. The system of claim 10, wherein the belt comprises a plurality of holes that define the air permeable surface and through which the vacuum source pulls air to create a negative pressure proximal to the air permeable surface.

13. The system of claim 12, wherein the vacuum source comprises a vacuum pump that is disposed beneath the air permeable surface.

14. The system of claim 10, wherein the sensor comprises a vacuum switch.

15. The system of claim 10, further comprising a reject assembly, that is coupled to the sensor, and that is operative to reject the container in response to the sensor if the sensor detects the pressure decrease.

16. The system of claim 15, further comprising a controller, that is coupled to the pressure sensor and the reject assembly, the controller being operative to control the reject assembly in response to the sensor.

18. The method of claim 15, wherein the vacuum source comprises a vacuum pump.

17. A method of detecting the presence of an unwanted aperture in a container that has an opening, comprising:

disposing the container on a continuously moving air permeable surface of a conveyor;

continuously moving the conveyor so that the opening passes proximal to a stationary pressure sensor, the opening being placed in fluid communication with the sensor as the container passes proximal to the pressure sensor;

pulling air with a vacuum source through the air permeable surface while the container passes proximal to the sensor, and if the container has the unwanted aperture, pulling air from within the container and through the unwanted aperture and thereby causing a decrease in pressure within the container while the sensor is in fluid communication with the container; and

sensing a pressure within the container when the container is placed in fluid communication with the sensor and while the air permeable surface is continuously moving and if the container has the unwanted aperture detecting the decrease in pressure created by the vacuum source when the conveyor moves the container proximal to the sensor, thereby determining if the container has an unwanted aperture by determining the pressure decrease in the container.

19. The method of claim 17, wherein the step of continuously moving further comprises moving the air permeable surface so that the container is disposed beneath a sensor mounting block in which the sensor is disposed.

20. The method of claim 17, further comprising the step of rejecting the container if the container is determined to have the unwanted aperture by activating a reject assembly, that is coupled to the pressure sensor, the reject assembly being operative to contact the container and knock the container off of the air permeable surface in response to the pressure sensor detecting the decrease in pressure.

21. The method of claim 20, wherein the step of sensing comprises sensing the pressure with a sensor that is in communication with a controller that controls the reject assembly to reject the container if the sensor detects the decrease in pressure within the container.