Vacuum valve and monitoring system

A removable vacuum indicator valve, horizontally affixed to the outside of an evacuated container, such as a flat-plate solar energy collector, wherein a movable sphere inside the valve is positioned to open or close the valve by the force of gravity or atmospheric pressure. The sphere, in open position, indicates the loss of vacuum and completes an electrical circuit which automatically activates a pump for restoring the vacuum to the container. The vacuum indicator valve, in combination with a normally closed valve installed permanently inside the evacuated container, and a remote electrically activated vacuum pumping system, provides a simple, inexpensive method for permanently maintaining and monitoring the vacuum in the container.

BACKGROUND OF THE INVENTION 
This invention relates generally to improvements in the means for 
monitoring and maintaining a vacuum, or partial vacuum, within relatively 
large containers, and more particularly to an inexpensive means for 
permanently maintaining and monitoring evacuated, flat-plate solar 
collector units. 
Until now, there has been no specific need or demand for the use of large, 
permanently evacuated containers, except within specialized industries and 
for military and research use. The existing applications generally require 
accurate pressure measurement devices and precise valving and control 
systems, and they can justify the large cost involved in the use of 
standard pressure gauges, valves and monitoring systems now available for 
the purpose. However, the high cost of such gauges and valve systems 
precludes their use in any application that requires a simple, 
non-critical means for permanently maintaining and monitoring a vacuum, as 
in evacuated solar collector systems. In an evacuated solar collector 
system, for instance, a loss of vacuum and complete failure of the pumping 
system would merely reduce the operating efficiency of the collectors, but 
not prevent their continued operation. A further disadvantage of the 
standard gauges and valving systems presently available is that they 
require technical knowledge and skill for proper installation and 
servicing, making the impractical for applications where laymen might 
undertake such work, as in an evacuated solar collector system. 
SUMMARY OF THE INVENTION 
The present invention consists of a simple, inexpensive indicator valve for 
monitoring the vacuum within an evacuated container, coupled with an 
automatically controlled means for restoring vacuum losses that occur over 
a long period of time. This invention is particularly useful for 
flat-plate solar collector systems employing an evacuated space within the 
collector units. 
In accordance with the present invention, a vacuum indicator valve, 
consisting of a cylinder with a central, tubular orifice leading to an 
evacuated space at one end, and to atmospheric pressure at the other end, 
is removably attached to the side of an evacuated container. The valve is 
provided with a conical-shaped internal chamber and a movable sphere 
disposed within the chamber. The sphere, being a closure for the tubular 
orifice, is normally held in airtight contact with the orifice opening by 
atmospheric pressure. Upon the loss of vacuum within the container, 
gravity causes the sphere to move away from the orifice opening and to 
complete an electrical circuit which activates an automatic pumping system 
for restoration of the vacuum. The vacuum indicator valve, combined with a 
normally closed valve within the evacuated container, and the 
electrically-activated, automatic pumping system, provides a complete and 
inexpensive means for monitoring and maintaining a permanent, evacuated 
condition within a large, sealed container. 
Accordingly, it is an object of this invention to provide a vacuum valve 
for applications where a vacuum, or no-vacuum, indicator means can be used 
instead of pressure differential readings provided by conventional, more 
expensive pressure gauges. 
It is also an object of this invention to provide a vacuum monitoring 
system that can be installed and serviced at the site of the evacuated 
container, without special knowledge or skill. 
Another object of this invention is to provide a vacuum-maintenance system 
for non-critical applications that are able to function adequately with a 
loss of vacuum, until the restoration of vacuum takes place. 
Another object of this invention is to provide a vacuum, or no-vacuum 
indicator means that also acts as a switching device to operate a vacuum 
pump to restore the vacuum. 
A further object of this invention is to make evacuated, flat-plate solar 
collector systems economically feasible and practical for residential and 
commercial use. 
In accordance with these and other objects which will be apparent 
hereinafter, the instant invention will now be described with particular 
reference to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in detail to the drawings, wherein an embodiment of the 
present invention is shown, and referring particularly to FIG. 1, a vacuum 
indicator valve, generally designated as numeral 1, is illustrated as 
being fastened in a horizontal operating position to an evacuated 
container wall 23 by means of a threaded end 14, with the connection being 
made airtight by a resilient gasket 13. Within the evacuated flat plate 
collector frame or container area indicated by numeral 8, a leaf-type 
valve inside casing 28 is permanently fastened with an airtight adhesive 
at 29 to the container wall 23. This leaf-type valve, also shown in FIG. 
5, is normally closed to prevent loss of vacuum in the container during 
shipment or installation and during insertion and removal of vacuum 
indicator valve 1. It also permits a threaded-end vacuum hose, not shown, 
to be used for evacuation of the container, in the event that the vacuum 
indicator valve 1 is not being used. The normally-closed position of this 
leaf-type valve is illustrated in FIG. 5. The leaf 22 is held in mating 
contact with opening 25, which leads to the evacuated area, by the force 
of a spring, not shown, at hinge point 26, or by a resilient pad 27 acting 
upon the leaf extension 24. The leaf 22 may be surfaced with a resilient 
plastic or rubber material to provide an airtight seal over the opening 
25. 
Referring again to FIG. 1, upon insertion and seating of the vacuum 
indicator valve 1 into the container wall 23, the valve leaf 22 is opened 
by the advancing force of the threaded valve end 14, acting upon the leaf 
extension 24. As a result, the area of evacuation 8 is extended through 
the opening 25 and through opening 4 to the surface 10 within the 
indicator valve 1. The indicator valve 1, being generally of cylindrical 
shape, has a central, tubular orifice leading into the evacuated container 
at one end 4 and to the outside atmospheric pressure area indicated by 
numeral 7 at the other end 3. The tubular orifice, at its mid-section, 
opens into a centrally located, conical-shaped chamber 6, having an 
interior surface that converges towards orifice end 4. The walls of 
chamber 6 may be formed by the insertion of a conical ring 20 and a 
cylindrical element 15, into the valve body 2. An unattached sphere 5, 
free to move within the chamber 6, is normally held in airtight, mating 
contact with the curved chamber surface 21 by atmospheric pressure acting 
upon sphere surface 17, thereby closing the orifice opening 10. The 
surface 21 may be covered or lined with a resilient plastic or rubber 
material to provide an airtight seal. Upon the loss of vacuum in area 8, 
the pressure differential between the surfaces of the sphere at 10 and 17 
is reduced, permitting gravitational force to move the sphere away from 
its closure position at 10. The sphere then rolls down the inclined 
surface of ring 20 into position 16, exposing a continuous air-flow path 
from orifice 3 through the chamber at 11, to the orifice end 4 and into 
the container through opening 25. 
If the valve element 20, ring 15 and sphere 5 are made of 
electrically-conductive material, such as copper, aluminum or plated 
steel, the sphere 5 in position 16 will provide an electrical connection 
between ring 20 and element 15 at resting point 9. Terminals 18 and 12, 
inserted through valve body 2, into the element 15 and ring 20, 
respectively, provide an exterior electrical connection for this circuit 
which may be used to signal the loss of vacuum in the container area 8. 
The valve elements 20, 15, and 5 are switching elements. An external pair 
of wires, carrying low-voltage potential, may be connected to terminals 12 
and 18, and to a remote control area to activate a pump which will restore 
the vacuum to the container area 8. The vacuum may be restored through a 
rigid or flexible hose 19, connected at one end to a shoulder on the valve 
body 2 and at the other end to the remote area pump. 
Referring now to FIG. 2, in its simplest and most economical form, the 
valve body 38 may be made of transparent plastic and the sphere 30 may be 
made of brightly-colored plastic, to provide instant visual confirmation 
of the sphere position 30 which indicates loss of vacuum. The orifice end 
32, leading to the atmosphere, may be protected from the weather with a 
cap 34 having small-diameter openings 35 to maintain atmospheric pressure 
at the orifice 32. The orifice 32 may have a flat insert 33 across its 
diameter and protruding into the valve chamber to prevent the sphere 30 
from blocking the orifice opening during the evacuation procedure. Upon 
the loss of vacuum, the cap 34 may be removed and replaced with a hose 
leading to the vacuum pump to facilitate the restoration of vacuum. At the 
end of the evacuation procedure, when atmospheric pressure is restored to 
the orifice 32 by removal of the vacuum pump hose, the initial rush of air 
through the orifice 32 will force the sphere into closure position 31, 
sealing off the evacuated area. 
FIG. 4 illustrates some of the valve design variables, such as orifice 
diameter 63, sphere mating surface 62 material and configuration, sphere 
61 weight and composition, incline angle 60 of the chamber wall, and 
configuration of the chamber wall 64, which may be used to satisfy the 
different operational requirements of specific vacuum monitoring 
applications. 
Referring back to FIG. 1, wherein all of the parts of the invention are 
utilized for completely automatic maintenance of a vacuum, the remote area 
pump connected to hose 19 on valve body 2 might normally remain inactive 
for many weeks or months at a time, depending on how well the vacuum 
container has been sealed. Daily, or more frequent operation of the vacuum 
pump would indicate the need for locating the leak and resealing the 
container. Where many, separate, evacuated containers are in use, such as 
a group of flat-plate solar collector units, the electrical terminals 12 
and 18, and hose 19 from each indicator valve 1, may be combined to 
operate from a single control center and pumping system. 
FIG. 3 is a generalized diagram of a control center for the operation of a 
multiple, evacuated container system. The individual hoses 41, leading to 
the evacuated containers in area 42, may be connected to a manifold 47 
inside housing 45, from which a single hose 48 leads to the remote area 43 
of the pump 55. Hose 41 may be connected to the device 1 in FIG. 1 as hose 
19 is connected. Similarly, the indicator valve wires 40 may be connected 
to terminals inside a weatherproof terminal box 53. A single, multi-wire 
cable 51 may carry all of the wires from the terminal box 53 to the remote 
control area 43. Each of the indicator valves may be connected to its own 
signal lamp 52 through a lowvoltage source or battery 50, and to a relay 
56. The closing of a valve circuit, due to loss of vacuum in any of the 
containers, would light the corresponding signal lamp 52 and also energize 
the pump circuit through relay 56. The pump 55, powered by voltage source 
54 activated by relay 56, and controlled by timer 49, would restore vacuum 
to all containers through hose 48. The timer 49 may be set for daytime 
pumping operation and for a preset pumping time period or cycle, as 
determined by the evacuated container and hose volumes and the pump 
capacity. If desired atmospheric pressure may be rapidly restored within 
the connecting hoses 48 and 41 and 19, at the end of the pumping cycle, by 
means of a conventional, normally open, electrically operated solenoid 
valve 44, or any other suitable air valve, installed either on the 
manifold 47 or on the hose leading out of the pump housing at 45. This 
instantaneous restoration of atmospheric pressure to the hoses 41 and rush 
of air into the vacuum indicator valves will cause all valve spheres to 
return to closed positions and all light signal 52 to be extinguished, 
thereby indicating that the system is functioning properly and that vacuum 
has been restored to all containers. During operation of the pump 55, a 
faulty or non-operative indicator valve on any of the containers would 
fail to light its corresponding signal lamp 52, prior to the end of the 
cycle. The vacuum pump 55 may be manually activated periodically, to 
insure the proper level of evacuation in all containers and to verify that 
all valves and signal lamps 52 are in working order. 
The vacuum pumping and monitoring system described herein may be combined 
with advanced micro-circuitry controls for greater flexibility or economy 
of operation. Furthermore, the indicator valves and pumping system may be 
used for other and additional applications that might benefit from the 
evacuated-container type of insulation on their outer surfaces, such as 
hot water storage tanks, refrigeration units and other large appliances 
that operate at temperatures above or below their surrounding temperature. 
These new applications would require only the addition of a hose and 
electrical connection to an existing vacuum monitoring and pumping system. 
It should be noted that this system is of particular use in an evacuated, 
flat-plate solar collector that includes an airtight outer frame defining 
an opening in which an essentially flat, black collector plate is disposed 
within the frame, a means for collecting heat connected to the collector 
plate, at least one transparent plate positioned above the collector plate 
for admitting solar radiation to the collector plate wherein it is 
converted to useable heat energy, and a back cover plate positioned below 
the collector plate for retaining an insulation means. 
The instant invention has been shown and described herein in what is 
considered to be the most practical and preferred embodiment. It is 
recognized, however, that departures may be made therefrom within the 
scope of the invention and that obvious modifications will occur to a 
person skilled in the art.