Measuring and testing – Instrument proving or calibrating – Fluid pressure
Reexamination Certificate
1999-04-21
2001-01-09
Raevis, Robert (Department: 2856)
Measuring and testing
Instrument proving or calibrating
Fluid pressure
C073S001680
Reexamination Certificate
active
06170316
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a tool for testing pressure and vacuum switches. More particularly, the invention relates to a tool for measuring the pressure or vacuum at which an engine control switch “makes or breaks” contact.
BACKGROUND OF THE INVENTION
Engine control switches are used in air compressors, auxiliary generators, water pumps, marine engines, and various other devices. The switches are set to “make or break” an electrical contact at a predetermined pressure or vacuum within the switch. Typically, to test the pressure or vacuum at which these switches “make or break” contact, the switches must be installed in automobiles or other mechanically operated equipment. That causes problems because it is difficult and time consuming to install control switches in engines, compressors, pumps, automobiles, etc. Therefore, if a defective or improperly set engine control switch is installed in an automobile or other engine driven unit, the switch may not be determined to be defective or improperly set until after the switch is already installed. Thus, the switch must be removed, adjusted or replaced, and then reinstalled. This may need to be repeated several times before the switch is properly set or replaced to correct pressure or vacuum setting problems. This consumes valuable time and resources which would not need to be expended if a switch could be tested prior to installation.
These and other problems exist.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome these and other drawbacks in existing systems.
Another object of the present invention is to provide a single tool for testing engine control switches prior to installation.
Another object of the present invention is to provide a tool for determining the pressure or vacuum at which an engine control switch “makes or breaks” contact.
Another object of the present invention is to provide a tool that provides a visual indication of when a switch “makes or breaks” contact.
Another object of the present invention is to provide a tool for testing engine control switches which sets the “make or break” pressure of an engine control switch.
These and other objects of the invention are achieved according to various embodiments of the invention. According to one embodiment, a tool for testing engine control switches uses fluid pressure or a vacuum for determining the pressure or vacuum at which an engine control switch “makes or breaks” contact. The tool uses a rod and piston arrangement to apply a pressure or vacuum to the switch being tested. The piston and a portion of the rod are housed within a first housing (along with a fluid chamber comprising a fluid) and the remaining portion of the rod (surrounded by a return spring), a lock-and-swivel joint, and a portion of a threaded rod are housed within a second housing. The threaded rod extends through the second housing and exits through an outer passage at a side opposite the first housing. An adjusting knob is disposed at the exterior end of the threaded rod.
The first housing has a pressure chamber connected to the fluid chamber side and comprises a valve. The pressure chamber is also attached to a testing chamber having a receptacle for receiving a standard hollow threaded screw provided on an engine control switch and has a pressure/vacuum gauge attached thereto. The receptacle may be provided with a plug to prevent leakage of fluid from the fluid chamber.
The second housing may also be provided with mounting plates extending from the second housing. The mounting plates may be used for securing a battery to the second housing and have wires attached thereto. The ends of the wires are provided with clips for attaching to terminals of a switch. Preferably, one of the wires comprises a light bulb for providing a visual indication of when the switch “makes or breaks” contact.
According to one embodiment, the tool may be used to measure the pressure at which an engine control switch “makes or breaks” contact. In this embodiment, the plug is removed from the receptacle and the standard hollow threaded screw provided on the switch is inserted into the receptacle. The clips on the wires are attached to the terminals of the switch and the valve is opened by rotating the adjusting knob in a direction which increases the pressure within the pressure chamber (e.g, clockwise). The adjusting knob is rotated until the light bulb illuminates. When the light bulb illuminates, this indicates that contact has been made within the switch. A reading of the pressure/vacuum gauge identifies the pressure at which the switch makes contact.
According to another embodiment, the tool may be used to test vacuum switches. In this embodiment, the valve is opened by rotating the adjusting knob in a direction which increases pressure in the pressure chamber and expels fluid therefrom (e.g., clockwise). The switch is inserted into the receptacle and the clips are attached to the terminals of the switch. The adjusting knob is then rotated in the opposite direction to create a vacuum (e.g., counter clockwise). The adjusting knob is rotated until the light bulb either illuminates or extinguishes (depending on whether the switch is a “make” or “break” switch). When the light bulb changes operation (i.e., on or off), this indicates that the vacuum point at which the switch “makes or breaks” contact has been achieved. A reading of the pressure/vacuum reveals the vacuum reading for this point.
These and other objects, features, and advantages of the invention will be readily apparent to those having ordinary skill in the pertinent art from the detailed description of the preferred embodiments with reference to the appropriate figures.
REFERENCES:
patent: 2490821 (1949-12-01), Leonard
patent: 3720090 (1973-03-01), Halpert et al.
patent: 3831391 (1974-08-01), Blomstrand
patent: 3927553 (1975-12-01), Frantz
patent: 4658829 (1987-04-01), Wallace
patent: 4664635 (1987-05-01), Hermann
Clinton L. Aldrich
Hunton & Williams
Raevis Robert
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