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|United States Patent Application
Anderson, Robert W.
July 29, 2004
Portable air compressor/tank device
A portable, low cost air supply device for accumulating and dispensing
compressed air converted from photovoltaic energy. The device includes
one or more photovoltaic cells, a capacitor, an electronic trigger
device, a solenoid, a valve manifold, a reservoir, and a device for
dispensing accumulated air. The photovoltaic cell(s) charge the small,
low cost capacitor. When saturated, the capacitor is triggered by a
solid-state device to discharge the electrical charge to a solenoid. The
energized solenoid then extends its plunger into a hole in the valve
manifold, compressing air into the manifold. The compressed air moves
past a check valve, and into a storage reservoir. The solenoid rapidly
de-energizes, the plunger retracts, and the solenoid is now ready for
another compression stroke.
Anderson, Robert W.; (Wichita Falls, TX)
Mr. Edward J. Timmer
P.O. Box 770
November 12, 2003|
|Current U.S. Class:
||417/63; 417/411 |
|Class at Publication:
||417/063; 417/411 |
1. A self replenishing, portable air supply device, comprising an air
reservoir tank, one or more photovoltaic cells exterior of the air
reservoir tank, a capacitor for receiving electrical power from the one
or more photovoltaic cells and intermittently discharging to a solenoid,
said solenoid then mechanically compressing air into the air reservoir
2. Air supply device of claim 1 wherein the capacitor and solenoid are
disposed inside the air reservoir tank.
3. Air supply device of claim 1 including a flashlight disposed on the air
4. Air supply device of claim 1 including a self-retracting hose reel
disposed on the air reservoir tank.
5. Air supply device of claim 1 including a hose pressure indicating gauge
with pressure readout disposed on the air reservoir tank.
6. Air supply device of claim 1 including a manually activated valve
disposed on the air reservoir tank to dispense compressed air.
7. Air supply device of claim 1 including a connector to secure the air
reservoir tank in a location of use.
8. Air supply device of claim 7 wherein the connector secures the air
supply device on a pick-up truck bed.
9. Air supply device of claim 1 including a one or more photovoltaic cells
for location remote from the air reservoir tank.
10. A self replenishing, portable air supply device, comprising an air
reservoir tank and one or more photovoltaic cells exterior of the air
reservoir tank to power an air compressor pump which resides inside the
11. A self replenishing, portable air supply device, comprising an air
reservoir tank, one or more photovoltaic cells exterior of the air
reservoir tank to provide electrical power to a power storage device,
which intermittently provides electrical power to an air compressor pump.
12. The air supply device of claim 11 wherein the air compressor pump
receives atmospheric air to be compressed via a check valve on the tank.
13. A method of supplying compressed air, comprising generating
photovoltaic electrical power using light exterior of an air reservoir
tank, storing the electrical power, and intermittently providing the
stored power to an air compressor pump to pressurize the air reservoir
14. The method of claim 12 including intermittently providing the stored
power to an air compressor pump inside the air reservoir tank.
15. An air reservoir tank having a manually activated air dispensing
16. The tank of claim 15 wherein the air dispensing valve is a pushbutton
or a pivotable lever that engages the pushbutton.
17. An air reservoir tank having a flashlight thereon.
18. The tank of claim 17 wherein the flashlight provides a carry handle
for the tank.
19. The tank of claim 17 including a photovoltaic cell to supply
electrical power to charge the flashlight.
20. An air reservoir tank having an air dispensing hose disposed on a reel
that retracts the hose when it is not in use.
21. An air reservoir tank having an air pressure gauge to display air
discharge pressure in the hose.
22. An air reservoir tank having a connector by which the tank can be held
 This application claims the benefits of provisional application
Serial No. 60/426,294 filed Nov. 14, 2002.
FILED OF THE INVENTION
 The invention relates to a portable, low cost air supply device for
accumulating and dispensing compressed air and powered by photovoltaic
BACKGROUND OF THE INVENTION
 U.S. Pat. No. 6,367,259 describes an air compressor system that
includes a rotary induction motor, motor control circuitry, expensive
large capacitors, and associated packaging. To date, air compressor
systems that accumulate energy from photovoltaics have been made up of
conglomerations of large static devices, working together and coordinated
by complicated control circuitry and sensors. These systems are commonly
formatted as banks of batteries or banks of large expensive capacitors.
Such storage devices drive induction motors, which then finally drive
SUMMARY OF THE INVENTION
 An embodiment of the invention provides an air supply device and
method that accumulate and distribute compressed air without the use of
the large static devices referenced above, that can be hand carried to
the point of use with a size scale easily applied by the end user, and
that eliminates the need for a rotary induction motor, motor control
circuitry, expensive large capacitors, and associated packaging.
 One illustrative embodiment of the invention involves a
self-replenishing, portable air supply device that includes an air
reservoir tank and one or more photovoltaic cells disposed exterior of
the air reservoir tank. The photovoltaic cell(s) provide(s) electrical
power to a capacitor, which intermittently discharges to a solenoid,
which then mechanically compresses air into the reservoir tank. In a
preferred embodiment of the invention, the capacitor and solenoid and
other related components are located inside the air reservoir tank.
 The invention optionally provides on the air reservoir tank one or
more of a flashlight, a self-retracting hose reel, a hose pressure
indicating gauge/LCD readout, a manually activated valve to dispense
compressed air, and a connector to secure the portable reservoir tank in
a location of use (i.e. pick-up truck bed). The invention also envisions
optionally providing one or more remote-mounted photovoltaic cell(s) to
allow the air supply device to serve as an imbedded power unit within a
 The invention is advantageous to improve the manufacturability and
affordability of a portable air compressor system by virtue of reduced
number of component parts, simplified integral packaging (placing
sensitive components inside the air reservoir tank), and enabling the use
of a very small, and exponentially cheaper capacitor. Other advantages of
the invention will become more readily apparent from the following
description taken with the following drawings.
DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a schematic view of an air supply device pursuant to an
embodiment of the invention shown for use in inflating a pick-up truck
 FIG. 2 is a perspective view of an air supply device to an
embodiment of the invention with the air reservoir tank partially broken
away to show the portion of the solenoid pump assembly residing inside
 FIG. 2A is an enlarged view of the solenoid pump assembly.
 FIG. 3 is a sectional view of the solenoid pump assembly and air
reservoir tank wall, depicting the pneumatic circuit. The circuit board B
and capacitor and trigger device thereon are shown schematically for
 FIG. 4 is a schematic view showing the photovoltaic cells and
related electronic components relative to the air reservoir tank,
depicting the electrical circuit.
 FIG. 4A is an enlarged view of the electrical trigger device of
 FIG. 5 is a perspective view of the air supply device showing the
air reservoir tank having thereon a flashlight, a self-retracting hose
reel, a hose pressure indicating gauge/LCD readout, a manually activated
valve to dispense compressed air, and a locking lug to secure the
portable reservoir tank in locations of use (i.e. pick-up truck bed).
 FIG. 6 is a perspective view showing the air supply device having a
lug for mounting the air supply device on the bed of pick-up truck.
 FIG. 7 is an elevational view of the air supply device having a
manual trigger thereon actuated to dispense compressed air from the air
 FIG. 7A is an enlarged view of the manual trigger.
DESCRIPTION OF THE INVENTION
 Referring to FIG. 1, an air supply device and method pursuant to an
illustrative embodiment of the invention comprises an air reservoir tank
1 of conventional fabrication (mild steel, or aluminum, or plastic
composite construction) with an integral carry handle 21 and attached
supporting feet 20 for resting on a horizontal surface. A pipe nipple 2,
FIG. 2 is disposed on and extends through and into the air reservoir tank
1. A solenoid pump assembly 19 is configured as a plug received in the
pipe nipple 2, with certain mechanical and electrical circuitry of the
solenoid pump assembly disposed in, and totally enclosed within, the air
reservoir tank 1 as will become apparent below.
 On the exterior surface of tank 1 is/are mounted one or more
photovoltaic cell(s) 14. The energy from the photovoltaic cell(s) 14 is
used to charge intermittently solenoid 8 of the solenoid pump assembly 19
using an electrical circuit shown in FIG. 4. Solenoid 8 and its enclosed
plunger 7 reside in the tank 1, FIG. 3, and are configured to function as
an air compressor pump when combined with valve manifold 11. The solenoid
8 includes a housing with a threaded or flanged end that is threaded or
bolted onto the valve manifold 11 to join them together as shown in FIG.
3. The combination of the solenoid 8 and valve manifold 11 is referred to
as the solenoid pump assembly 19. On it's retract stroke, plunger 7,
functioning as a piston, draws atmospheric air through the externally
protruding tank valve 3 of the solenoid pump assembly 19. Once the
solenoid 8 is energized, plunger 7 advances, compressing air past
spring-biased check valve 13 and into the air reservoir tank 1. The
solenoid 8 can be a commercially available solenoid, such as Ledex brand
size 3EC model available from Saia-Burgess, Inc.
 The valve manifold 11 has attached, or built integral to it,
devices including 1) a pressure relief valve 6, to prevent tank 1 over
pressurization; and 2) a Schrader style tank valve 3, functioning as an
air intake, back flow check valve, and allowing the filling of tank 1
from an external compressed air source. Further devices attached or built
integral to manifold block 11 include gauge port 5 for mounting a
pressure indicator 27 for gauging discharge pressure; discharge hose
connector 12; and optional discharge valve 10 for manually controlled
dispensing of compressed air. Discharge hose 4 is a flexible tube
connected to discharge hose connector 12. Discharge hose 4 is used for
dispensing compressed air from within tank 1, and can be configured as a
static shape, coiled, or combined with an optional self-retracting hose
reel 23 as shown in FIG. 5.
 An electrical trigger device 16, FIG. 4, is provided and determines
when there is enough electrical charge (energy) stored in capacitor 15 as
an electrical power storage device to energize solenoid 8. Capacitor 15
will be of low cost and small size, generally in the 2200 micro Farad
size range. The trigger device 16 in its essential embodiment includes a
diode 16a and transistor 16b arranged as shown in FIG. 4A that function
together to detect a fully charged capacitor 15, distribute this stored
energy to solenoid 8, and then reset the circuit so that the energy
supplied by photovoltaic cell(s) 14 can recharge capacitor 15 to repeat
the cycle. The capacitor 15 trigger device 16 and other electrical
components are mounted on a circuit board B located inside the tank 1,
FIG. 2. The circuit board is fastened by a U-shaped bracket to the
solenoid housing as shown in FIG. 3. If it is desired to give an
indication external of the tank 1 that the solenoid 8 is energized, LED
17 can be optionally installed in the circuit as shown in FIG. 4. A
current limiting device 18, which may comprise a resistor, may be
required in the circuit dependent on the current handling characteristics
of photovoltaic cell(s) 14.
 The air supply device also may contain the following optional
features: (a) a pressure switch 28 to shunt excess electrical potential
from photovoltaic cell(s) 14 to the charging of a rechargeable flashlight
22, FIG. 5, that is disposed on, and preferably built integral to the
carry handle 21 such that the flashlight body functions as the carry
handle for tank 1; (b) an AC/DC or DC/DC power adapter 29 for powering
the air supply device from an external electrical source; (c) a C-shaped
(or other shaped) strap connector 24, FIG. 6, which is fastened on the
air reservoir tank 1 and which receives and is lockable onto an elongated
male bracket 25 attached to a truck bed, FIG. 6 (or other structure) when
the air supply device is positioned on the truck bed proximate the front
wall thereof so as to prevent the theft of the device, the bracket 25
having a punched or otherwise-formed hole to receive a common padlock in
a manner that also passes through the strap connector 24 to lock the
connector and the bracket together; (d) air dispensing valve 10 movable
relative to valve seat 10a and configured as a manually depressed button,
or activated by a lever 30 disposed on a carrying handle 21 attached to
tank 1, FIG. 7, such that when the lever 30 is manually squeezed, the
lever rocks on pivot pin 31 in a manner to depress air dispensing valve
10, which than opens relative to seat 10a and supplies compressed air to
the discharge hose 4; and (e) a pressure gauge 26, FIG. 5, for indicating
tank air pressure. In an alternative embodiment of the invention, the
discharge hose connector 12 can be omitted and replaced with hard piping
so that the air supply device can be used as an integral power supply
subcomponent to a larger system. The air reservoir tank 1 may or may not
require customizing to conform within the encompassing larger system and
may or may not require the remote location of the photovoltaic cells 14
as a power source. Still further, the solenoid pump assembly 19
alternatively may be mounted or disposed externally to an air reservoir
tank 1 as either a retrofit to an existing passive air tank, or as an
alternative way to construct an air supply device pursuant to another
embodiment of the invention.
 In operation, photovoltaic cell(s) 14 produce electric current
through exposure to any incident light energy. The electric charge is
stored in capacitor 15. Once capacitor 15 achieves a charge sufficient
enough to overcome the breakdown voltage of the trigger device 16, the
electrical charge is then free to pass through to the coil of solenoid 8,
FIG. 4, to power the solenoid. An energized solenoid 8 creates an
electromagnetic flux passing through the center of the solenoid 8.
Plunger 7, which is located in the center of solenoid 8, resists the
electromagnetic flux, which causes plunger 7 to thrust rapidly upwards
out of solenoid 8. The air on the leading surface of plunger 7 is
compressed through check valve 13 and into the air reservoir tank 1. The
charge in the capacitor is diminished rapidly and plunger 7 self centers
back into solenoid 8 as the flux relaxes. Gravity helps the plunger 7
retract into the solenoid coil in vertical plunger orientations as shown
in FIG. 3. In other plunger orientations or to speed up retraction of the
plunger 7, a retract spring 32 optionally may be provided as shown in
FIG. 3 to bias the plunger to this end. Additional plunger retraction
speed can be achieved by modifying the trigger device 16 to not just
relax the current flow in solenoid 8, but to reverse the current flow to
thereby forcibly retract the plunger 7 within the solenoid 8. The
withdrawal of plunger 7 creates a slight low-pressure area within the
cavity of valve manifold 11. This vacuum is relieved by atmospheric air
pressure overcoming the valve stem seating pressure in Schrader style
tank valve 3 and enters the valve manifold 11 internal cavity. The air
supply device is now ready for another cycle. The frequency of cycles
will depend on available light, but will most likely not exceed 2 cycles
per second at maximum sunlight due to the duty cycle limitations of most
commonly commercially available solenoids.
 Once the air reservoir tank 1 is at the maximum designed pressure,
the backpressure from the compressed air will counterbalance the thrust
force of plunger 7, and the plunger 7 will no longer be able to further
compress air into the tank. Plunger 7 will be stalled, with capacitor 15
continuing to dissipate energy into solenoid 8. This "self maintaining"
mode can be held indefinitely until gradual leakage reduces air volume to
the point where the plunger 7 can move forward and replace the escaped
air. Alternatively, a pressure switch 28 can detect a full tank of air,
and disconnect the solenoid driving circuit shown in FIG. 4. The pressure
switch 28 can then optionally redirect the electric potential to charging
a flashlight 22, which would be beneficial for nighttime use of the
invention. The flashlight 22 may be built into the carry handle 21 of
tank 1 so as to prevent loss/theft of the light. The flashlight 22 will
shine across and illuminate the pressure indicator 27 at gauge port 5 as
well as illuminate whatever equipment is receiving the compressed air
being dispensed from the air supply device.
 Although certain illustrative embodiments of the invention have
been described herein, those skilled in the art will appreciate that the
invention is not limited thereto and that changes, modifications and the
like can be made thereto without departing from the spirit and scope of
the invention as set forth in the appended claims.
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