This invention relates to electric vacuum valves.
Background and Summary of the Invention
In the use of vacuum for performing various functions, for example, in operating parts in an automotive vehicle, it is desirable to insure that the vacuum will function only when the automotive vehicle engine is functioning.
Accordingly among the objects of the invention are to provide a reliable, efficient electric valve which will function to insure that vacuum will be transmitted to the device being operated only when the vehicle engine is being operated.
Description of the Drawings
FIG. 1 is a longitudinal sectional view of the electric vacuum valve showing the electrical connections diagrammatically.
FIG. 2 is a part sectional elevational view of an electric vacuum valve embodying the invention.
FIG. 3 is a sectional view taken of a portion of the valve in FIG. 1.
FIG. 4 is a bottom plan view of the portion of the valve shown in FIG. 3.
Description
Referring to FIGS. 1-4, the electric vacuum valve 10 embodying the invention comprises a body 11 including a first part 12 and a second part 13 which are interengaged to define a chamber 14. The parts 12, 13 are made of plastic such as nylon. Part 12 includes an axial projection 15 having a first passage 16 communicating with the chamber 14. A valve seat is defined by rubber O-ring 17 held in position by an integral annular flange 18 that extends radially and axially inwardly.
A bi-metallic disc 19 is associated with the valve seat defined by O-ring 17 and has its periphery engaging a first shoulder 20 on body 11. A wave washer or spring 21 urges the bi-metallic disc 19 generally toward the shoulder 20.
A PTC disc 22 is mounted adjacent the disc 19 but in spaced relationship thereto so that heat radiating therefrom will cause the disc 19 to snap against the valve seat 17 and thereby prevent air from passing from a second passage 23 in part 13 through the chamber 14 and out through passage 16.
The terminal or electrical connections to the PTC disc 22 are made by a first terminal 24 in the form of a plate that is soldered to one side of the PTC disc 22 and has a leg 25 extending through a passage in part 13 to the exterior and a second terminal in the form of a plate 26 fastened to the other side of PTC disc 22 and having a leg 27 extending to the exterior. The legs 25, 27 include barbs 28, 29 that engage the outer surface of bosses in the part 13 to locate the PTC disc22 axially relative to the passage 16 and away therefrom.
As shown in FIG. 3, the disc 24 is formed with an elongated key-shaped opening 30 that has a greater length than the diameter of the surfaces of the interface between the disc 22 and the disc 24.
The disc 26 is fastened to the PTC disc 22 by solder S filling the opening 33 that has a cross sectional area less than the other surface of the PTC disc 22.
As further shown in FIG. 1, the terminal 24 engages a shoulder 34 in the chamber 14 and spring 21 urges the disc 19 against the shoulder 20.
When power is applied to the terminals 25, 27, (FIG. 1) by closing of switch indicating that the engine of the vehicle is operating, heat radiates from PTC disc 22 causing the bi-metallic disc 19 to snap to a closed position as shown in FIG. 2 preventing a venting of vacuum which is being applied to another device connected to passage 16. When the engine is stopped, the electrical connection to terminals 25, 27 is broken permitting the bi-metallic disc 19 to snap back to the position shown in FIG. 1 permitting communication from the exterior passage 23 through the passage 16 to the vacuum operating device.
A filter 35 in the form of an annular disc is provided over the passage 23 and is held in centered position overlying opening 23 by an axial wall 36 extending through the center of the filter.
To facilitate assembly of parts 12, 13 of body 11, the periphery of part 12 is provided with circumferentially spaced axially extending fingers or projections 37, each formed with a radial rib 38. Part 13 is forced axially inwardly to spring fingers 37 outwardly and to snap behind rib or portions 37.