U.S. patent application number 11/049115 was filed with the patent office on 2005-09-01 for portable electric driven compressed air gun.
Invention is credited to Pedicini, Christopher S., Witzigreuter, John D..
Application Number | 20050188974 11/049115 |
Document ID | / |
Family ID | 33556395 |
Filed Date | 2005-09-01 |
United States Patent
Application |
20050188974 |
Kind Code |
A1 |
Pedicini, Christopher S. ;
et al. |
September 1, 2005 |
Portable electric driven compressed air gun
Abstract
A portable electric motor driven air gun powered by a power
source. The motor is coupled to a lead screw, which drives a
piston. The piston compresses air in a chamber producing
high-pressure air. When sufficient energy is stored within the air
stream by the piston a valve opens which releases the air to act on
the projectile. The compressed air is used to push a projectile
such as a paintball, an airsoft ball, a "bb", or a pellet through a
barrel. The lead screw is then reversed and the piston is reset for
the next shot. The piston is preferably coupled to a feeding
mechanism to facilitate positioning of the projectile for firing.
The direction speed and operative modes of the gun are preferably
controlled with an electric circuit. The power source is preferably
rechargeable and allows the air gun to be operated completely
independent from either a wall outlet or a compressed air
supply.
Inventors: |
Pedicini, Christopher S.;
(Roswell, GA) ; Witzigreuter, John D.; (Kennesaw,
GA) |
Correspondence
Address: |
SMITH, GAMBRELL & RUSSELL, LLP
1230 PEACHTREE STREET, N.E.
SUITE 3100, PROMENADE II
ATLANTA
GA
30309-3592
US
|
Family ID: |
33556395 |
Appl. No.: |
11/049115 |
Filed: |
February 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11049115 |
Feb 2, 2005 |
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10764793 |
Jan 26, 2004 |
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6857422 |
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60477591 |
Jun 12, 2003 |
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60517069 |
Nov 5, 2003 |
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Current U.S.
Class: |
124/65 |
Current CPC
Class: |
F04B 9/02 20130101; F41B
11/71 20130101; F04B 35/01 20130101; F41B 11/64 20130101; F41A
19/58 20130101; F41B 11/57 20130101; F41B 11/681 20130101; F04B
35/04 20130101 |
Class at
Publication: |
124/065 |
International
Class: |
F41B 011/00 |
Claims
1. A compressed air gun for firing a projectile, comprising: a
barrel; a bolt moveable from a first position to a second position
for chambering at least one projectile; a motor; a power source in
electrical communication with the motor; a cylinder including a
front end and a rear end; a piston moveable within the cylinder and
adapted to compress air within the cylinder, the piston in
communication with the motor and moveable from a first position
adjacent the rear end of the cylinder to a second position adjacent
the front end of the cylinder, the piston mechanically linked to
the bolt; a compressed air passageway intermediate the cylinder and
the barrel; at least one valve intermediate the cylinder and the
compressed air passageway for supplying compressed air from the
cylinder to the compressed air passageway for firing a projectile
from the gun.
2. The compressed air gun according to claim 1, further comprising
a control circuit for controlling operation of the gun.
3. The compressed air gun according to claim 2, further comprising
a start switch in communication with the control circuit for
initiating actuation of the motor.
4. The compressed air gun according to claim 2, further including
at least one sensor in communication with the control circuit.
5. The compressed air gun according to claim 2, wherein the control
circuit further includes a switch which allows selection of
semiautomatic, burst mode or automatic firing.
6. The compressed air gun according to claim 2, wherein the control
circuit further comprises a microprocessor.
7. The compressed air gun according to claim 1, wherein the power
source is a battery.
8. The compressed air gun according to claim 1, wherein the motor
is a rotary motor, wherein the motor is connected to the piston by
a linear motion converter.
9. A compressed air gun for firing a projectile, comprising: a
barrel; a motor; a power source in electrical communication with
the motor; a bolt in communication with the motor and moveable from
a first position to a second position to chamber a projectile for
firing; a cylinder including a front end and a rear end; a piston
moveable within the cylinder and adapted to compress air within the
cylinder, the piston mechanically linked to the bolt and moveable
from a first position adjacent the rear end of the cylinder to a
second position adjacent the front end of the cylinder; a
compressed air passageway intermediate the cylinder and the barrel;
at least one valve intermediate the cylinder and the compressed air
passageway for supplying compressed air from the cylinder to the
compressed air passageway for firing a projectile from the
apparatus.
10. The compressed air gun according to claim 9, further comprising
a control circuit for controlling operation of the gun.
11. The compressed air gun according to claim 10, further
comprising a start switch in communication with the control circuit
for initiating actuation of the motor.
12. The compressed air gun according to claim 10, further including
at least one sensor in communication with the control circuit.
13. The compressed air gun according to claim 10, wherein the
control circuit further includes a switch which allows selection of
semiautomatic, burst mode or automatic firing.
14. The compressed air gun according to claim 10, wherein the
control circuit further comprises a microprocessor.
15. The compressed air gun according to claim 9, wherein the power
source is a battery.
16. The compressed air gun according to claim 9, wherein the motor
is a rotary motor, wherein the motor is connected to the piston by
a linear motion converter.
17. A compressor apparatus for a compressed air gun, comprising: a
motor; a power source in electrical communication with the motor; a
cylinder including a front end and a rear end; and, a piston
moveable within the cylinder and adapted to compress air within the
cylinder, the piston in communication with the motor and moveable
from a first position adjacent the rear end of the cylinder to a
second position adjacent the front end of the cylinder.
18. A method for firing a projectile from a compressed air gun
having a barrel, comprising the steps of: (a) providing a cylinder
housing a piston for compressing air within the cylinder by
movement of the piston; (b) providing a motor for moving the piston
within the cylinder; (c) providing a bolt mechanically linked to
the piston for chambering a projectile; (d) providing a compressed
air passageway intermediate the cylinder and the barrel; (e)
providing a valve intermediate the compressed air passageway and
the barrel; (f) supplying power from a power supply to the motor
for moving the piston and bolt; and, (g) selectively opening the
valve for allowing passage of compressed air from the cylinder to
the compressed air passageway for firing the projectile.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This utility application is a continuation of copending
nonprovisional patent application Ser. No. 10/764,793, filed on
Jan. 26, 2004, which is the nonprovisional application claiming
priority from Provisional Application No. 60/477,591, filed on Jun.
12, 2003, and Provisional Application No. 60/517,069 filed on Nov.
3, 2003, the entire contents of which are incorporated herein by
reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER LISTING
COMPACT DISK APPENDIX
[0003] Not Applicable
BACKGROUND OF INVENTION
[0004] This invention relates to pneumatic guns, air rifles, pellet
rifles, paintball guns and the like. Such pneumatic guns are
typically driven by either hand cocked springs, compressed gas, or
hand operated pumps. The disadvantages of these guns are outlined
in more detail below.
[0005] Air rifles have been around for many years and have seen
numerous evolutionary changes over the years. The most common
methods for propelling the projectile use the energy from
compressed gas or from a spring. There are four major techniques
shown in the prior art for launching the projectile with many
variations based upon such teachings. These techniques include: (i)
the use of stored compressed gas in the form of carbon dioxide
cylinders or other high pressure storage tanks; (ii) using a
powerful spring to push a piston which compresses air which then
pushes the projectile; (iii) using a hand pump to pressurize the
air for subsequent release; and (iv) using a direct acting means
such as a solenoid plunger or centrifugal force to push the
projectile out of the barrel. All of these methods have distinct
disadvantages when compared to the present invention.
[0006] The first technique requires a source of compressed air,
such as a tank or canister. Filling, transporting and using such a
canister represents a significant inconvenience and burden for the
user. Often, additional equipment such as regulators, evaporation
chambers, multistage regulators and complicated timing circuits are
required to reduce and control the very high pressure in the
cylinder to a level suitable for launching the projectile. This
further increases the cost and complexity of such an air gun.
Additionally, in the case of carbon dioxide driven air or paintball
guns, there is a large variation in the velocity of the projectile
with varying ambient temperatures. Furthermore, these tanks store
an incredible amount of energy which, if released suddenly through
a tank fault, could represent a significant safety factor.
Disposable cartridges, which can be used in less costly air guns,
significantly increase refuse issues. Additional teachings such as
those contained in U.S. Pat. Nos. 6,516,791, 6,474,326, 5,727,538
and 6,532,949 teach of various ways of porting and controlling high
pressure air supplies to improve the reliability of air guns
(specifically paintball guns and the like) by differentiating
between the airstream which is delivered to the bolt which
facilitates chambering the projectile and the airstream which
pushes the projectile out of the barrel. All of these patents still
suffer from the major inconvenience and potential safety hazard of
storing a large volume of highly compressed gas within the air gun.
Additionally, as they combine electronic control with the
propulsion method of stored compressed gas, the inherent complexity
of the mechanism increases, thus, increasing cost and reliability
issues. Further, U.S. Pat. No. 6,142,137 teaches about using
electrical means to assist in the trigger control of a compressed
air gun such as a paintball gun. In this patent, an electromotive
device is used in conjunction with electronics to define various
modes of fire control such as single shot, burst or automatic
modes. While this addresses the ability of multiple modes of fire,
it does not solve the fundamental propulsion problem associated
with gas cylinders and, in addition, it is expensive and
complicated.
[0007] The second technique is actually quite simple and has been
used for quite a few years in many different types of pellet, "bb"
or air rifles. The basic principle is to store energy in a spring
which is later released to rapidly compress air. This air then
pushes the projectile out of the barrel at high velocity. Problems
with this method include the need to "cock" the spring between
shots. Thus, it is only suitable for single shot devices and is
limited to very slow rates of fire. Furthermore, the spring results
in a double recoil effect when it is released. The first recoil is
due to the unwinding of the spring and the second recoil is due to
the spring slamming the piston into the end of the cylinder (i.e.
forward recoil). Additionally, the spring air rifles require a
significant amount of maintenance and, if dry-fired, the mechanism
can be damaged. Finally, the effort required for such "cocking" is
often substantial and can be difficult for many individuals.
References to these style air guns can be found in U.S. Pat. Nos.
3,128,753, 3,212,490, 3,523,538, and 1,830,763. Additional
variations on the above technique have been attempted through the
years including using an electric motor to cock the spring that
drives a piston. This variation is detailed in U.S. Pat. Nos.
4,899,717 and 5,129,383. While this innovation solves the problem
of cocking effort, the resulting air rifle still suffers from a
complicated mechanism, double recoil and maintenance issues
associated with the spring piston system. Another mechanism which
uses a motor to wind a spring is shown in U.S. Pat. No. 5,261,384.
Again, the use of indirect means to store the electrical energy in
a spring before release to the piston to push the projectile
results in an inefficient and complicated assembly. Furthermore,
the springs in such systems are highly stressed mechanical elements
that are prone to breakage and which increase the weight of the air
gun. A similar reference can be seen in U.S. Pat. No. 1,447,458
which shows a spring winding and then delivery to a piston to
compress air and propel a projectile. In this case, the device is
for non-portable operation.
[0008] The third technique, using a hand pump to pressurize the
air, is often used on low end devices and suffers from the need to
pump the air gun between 2 to 10 times to build up enough air
supply for sufficient projectile velocity. This again limits the
air rifle or paintball gun to slow rates of fire. Additionally,
because of the delay between when the air is compressed and when
the compressed air is released to the projectile, variations in the
energy are quite common for a standard number of pumps. Further
taught in U.S. Pat. Nos. 2,568,432 and 2,834,332 is a method to use
a solenoid to directly move a piston which compresses air and
forces the projectile out of the air rifle. While this solves the
obvious problem of manually pumping a chamber up in order to fire a
gun, these devices suffer from the inability to store sufficient
energy in the air stream. Solenoids are inefficient devices and can
only convert very limited amounts of energy due to their operation.
Furthermore, since the air stream is coupled directly to the
projectile in this technique, the projectile begins to move as the
air is being compressed. This limits the ability of the solenoid to
store energy in the air stream to a very short time period and
further relegates its use to low energy air rifles. In order to
improve the design, the piston must actuate in an extremely fast
time frame in order to prevent significant projectile movement
during the compression stroke. This results in a very energetic
piston mass similar to that shown in spring piston designs and
further results in the undesirable double recoil effect as the
piston mass must come to a halt. Additionally, this technique
suffers from dry-fire in that the air is compressed between the
piston and the projectile. A missing projectile allows the air to
communicate to the atmosphere through the barrel and can damage the
mechanism in a dry-fire scenario. Another variant of this approach
is disclosed in U.S. Pat. No. 1,375,653, which uses an internal
combustion engine instead of a solenoid to act against the piston.
Although this solves the issue of sufficient power, it is no longer
considered an air rifle as it becomes a combustion driven gun.
Moreover, it suffers from the aforementioned disadvantages
including complexity and difficulty in controlling the firing
sequence. Further taught in U.S. Pat. No. 4,137,893 is the use of
an air compressor coupled to a storage tank which is then coupled
to the air gun. Although this solves the issue of double recoil, it
is not suitable to a portable system due to inefficiencies of
compressing air and the large tank volume required. When air is
used in this fashion, it compresses via adiabatic means, but the
heat of compression is dissipated due to the large volume of air
and the subsequent storage in a tank. In order to overcome the
variation in air pressure, further expense and complexity in terms
of valving and regulators must be added. A variation of the above
is to use a direct air compressor as shown in U.S. Pat. No.
1,743,576. Again, due to the large volume of air between the
compression means and the projectile, much of the heat of
compression is lost leading to a very inefficient operation.
Additionally, this patent teaches of a continuously operating
device which suffers from a significant lock time (time between
trigger pull and projectile leaving the barrel) as well as the
inability to run in a semiautomatic or single shot mode. Further
disadvantages of this device include the pulsating characteristics
of the air stream which are caused by the release and reseating of
the check valve during normal operation.
[0009] The fourth technique is to use direct mechanical action on
the projectile itself. The teachings in U.S. Pat. Nos. 1,343,127
and 2,550,887 represent such mechanisms. Limitations of this
approach include difficulty in achieving high projectile velocity
since the transfer of energy must be done extremely rapidly between
the impacting hammer and the projectile. Additionally, this method
suffers from the need to absorb a significant impact as the
solenoid plunger must stop and return for the next projectile. This
can cause a double-recoil firing characteristic. Since the solenoid
plunger represents a significant fraction of the moving mass (i.e.
it often exceeds the projectile weight) this type of system is very
inefficient and limited to low velocity, low energy air guns as may
be found in toys and the like. Variations of this method include
those disclosed in U.S. Pat. No. 4,694,815 in which a hammer driven
by a spring contacts the projectile. The spring is "cocked" via an
electric motor, but again, this does not overcome the prior
mentioned limitations.
[0010] All of the currently available devices suffer from a number
of disadvantages, some of which include:
[0011] 1. Difficult operation. Cocking or pumping air rifles can be
time consuming and a physical chore.
[0012] 2. Inability to rapidly move between single fire,
semiautomatic, burst or automatic modes. Inability to support
rapid-fire operation required by the above.
[0013] 3. Significant inconvenience in the refilling transport and
use of high-pressure gas cylinders.
[0014] 4. Non-portability. Traditional air rifles at carnivals and
the like are tethered to a compressed air supply or due to
inefficient compressor operation require a large power source such
as a wall outlet.
[0015] 5. Double recoil effects.
[0016] 6. Complicated mechanisms and air porting schemes leading to
potentially expensive production costs and reliability issues.
[0017] 7. Inefficient usage and/or coupling of the compressed air
to the projectile resulting in low energy projectiles and large
energy input requirements.
BRIEF SUMMARY OF THE INVENTION
[0018] In accordance with the present invention, a piston is driven
by a lead screw, or other linear motion converter, to compress air
within a cylinder. When the desired pressure is reached a valve is
opened, or is allowed to open, releasing the high-pressure air
toward a projectile and launching the projectile. An electric
motor, which derives its power from a low impedance electrical
source, preferably rechargeable batteries, is coupled, either
directly or through, a reduction means to the lead screw creating a
very simple and robust design. Additionally, the piston may be
mechanically coupled to a bolt in order to force the bolt to move
in turn with the movement of the piston. Accordingly, besides the
objects and advantages of the portable electric air gun as
described, several objects and advantages of the present invention
are:
[0019] 1. To provide an electric motor driven gun in which the
operating element has an added degree of safety in that the energy
is on demand and not stored in high pressure cylinders.
[0020] 2. To provide a means in which the operation is portable
eliminating any tethering of hoses or cords.
[0021] 3. To provide a means in which the operation uses relatively
low pressure air thus reducing the sound profile and allowing for
stealth operation.
[0022] 4. To provide a means in which the control of the projectile
is enabled by electronic means thus increasing the safety profile
and speed control.
[0023] 5. To provide an electric motor driven gun in which the
source of energy is a rechargeable power supply thus eliminating
the use of disposable or refillable gas pressure cylinders and
decreasing overall operational cost.
[0024] 6. To provide an electric motor driven gun which is
mechanically simpler to construct and simpler to operate.
[0025] 7. To provide a means for reducing the lock time in a fire
on demand electric motor driven air gun.
[0026] 8. To provide a means in which the feed mechanism for the
projectiles is controlled by the electric motor thus allowing for a
simple design which does not rob energy from the air stream.
[0027] 9. To provide a means in which the compression is more
efficiently utilized by reducing the delay between compression and
firing, thus, accessing a large part of the heat energy of
compression.
[0028] 10. To provide a design which uses direct compression and
gets rid of intermediate elements like spring pistons and their
associated double recoil, weight and mechanism complexity.
[0029] Further objects and advantages will become more apparent
from a consideration of the ensuing detailed description and
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0030] Reference numbers for the drawings are shown below.
[0031] FIG. 1 is a side assembly view of the electric powered air
gun in the start position.
[0032] FIG. 2 is a side assembly view of the electric powered air
gun in the fire position.
[0033] FIG. 3 is a cutaway view of the preferred gearing for the
air gun.
[0034] FIG. 4 is a side assembly view of an alternate valve
scheme.
[0035] FIG. 5 is an enlarged side assembly view of the cylinder
REFERENCE NUMBERS IN DRAWINGS
[0036] 1 Motor
[0037] 2 Power Source
[0038] 3 Control Circuit
[0039] 4 Lead Screw
[0040] 5 Piston
[0041] 6 Bolt
[0042] 7 Spool
[0043] 8 Barrel
[0044] 9 Projectile
[0045] 10 Start Switch
[0046] 11 Magnet
[0047] 12 Sensor Switch
[0048] 13 Compressed Air Passageway
[0049] 14 Cylinder
[0050] 15 Bolt Link
[0051] 16 Projectile Inlet Port
[0052] 17 Bumper End of Stroke
[0053] 18 Solenoid
[0054] 19 Ball Detent
[0055] 20 Gear Reduction
[0056] 21 Pneumatic Air Supply
[0057] 22 Projectile Feeder
[0058] 23 Return Air Shock
[0059] 30 Lead Screw Shaft Adapter
[0060] 31 Planetary Clutch
[0061] 32 Planet Gear Carrier
[0062] 33 Ring Gear
[0063] 34 Planet Gear
[0064] 35 Reverse Clutch
[0065] 36 Pinion
[0066] 37 Motor Shaft Adapter
[0067] 38 Thrust Spacer
[0068] 39 Thrust Spacer
[0069] 40 Output Ball Bearing
DETAILED DESCRIPTION OF THE INVENTION
PREFERRED EMBODIMENT OF THE INVENTION
[0070] Although the following relates to the preferred embodiment
of the design, it will be understood by those familiar with the art
that changes to materials, part descriptions and activation methods
can be made without departing from the spirit of the invention.
[0071] Referring to FIG. 1, in the preferred embodiment, the user
presses a start switch (10) or trigger. This causes power to be
directed from the power source (2), such as a battery, to the motor
(1) by the control circuit (3). The preferred control circuit is
described later in further detail but can be as simple as any means
for connecting and disconnecting power to the motor to allow an air
compression and projectile fire cycle. The motor (1) begins to turn
causing energy to be stored in the rotating elements in the system.
The system includes a motor rotor and the lead screw (4). The lead
screw (4) is coupled to the motor (1), preferentially through a
planetary gear train, as shown further in FIG. 3. Furthermore, the
gearing is such that the forward and reverse gearing do not have to
be in the same ratio. For purposes of this design, the gearing is a
6:1 reduction in the forward direction and 1:1 direct in the
reverse direction. As the lead screw (4) turns it moves a piston
(5), which is coupled to the lead screw (4), down a cylinder (14)
and compresses the air in the cylinder (14). One means of coupling
the lead screw to the piston is through the use of a lead nut. At
or near the end of the piston (5) stroke, as shown in FIG. 2, the
spool (7) is allowed to shift open. This rapidly releases the
compressed air into the compressed air passageway (13) and then
into the barrel (8) of the air gun. The projectile (9), which is
located within the barrel (8), begins to accelerate under the force
of the compressed gas and is driven out of the barrel (8) at a high
velocity. The preferred embodiment uses a sensor switch (12) to
recognize when the piston (5) is in its approximate starting
position and ready for cycle initiation. The preferred switch is a
hall switch used in conjunction with a magnet (11), which is
attached to the piston (5). It is understood that any sensing means
which allows positional information of the piston could be used for
the sensor switch, including but not limited to: reed switches,
optical sensors and mechanical limit switches. Furthermore,
additional sensors could be attached to the pinion (36) which would
allow the control circuit (3) to determine the piston (5) location
by counting revolutions and processing the information as it
relates to the lead or linear inch per revolution of the lead screw
(4). Such information could be useful for altering the speed of the
piston (5) and or the release of the spool (7) by controlling the
power to the motor (1) and solenoid (18). At or near the point at
which the spool (7) shifts open, the motor can be reversed to bring
the piston back to the starting position. The spool operation in
the preferred embodiment is controlled by the solenoid (18) and/or
the ball detent (19). The spool (7) is maintained in the closed
position by using either a mechanical retention means such as the
spring and ball detent or electromotive retention means such as
from a solenoid (18) or both. The spool (7) release pressure can be
easily adjusted by increasing or decreasing the retention force
holding it in place. This provides a simple effective method for
changing the energy delivered to the projectile by increasing or
decreasing the pressure at which the spool (7) shifts open. In the
preferred embodiment, when the pressure in the cylinder (14)
reaches the set pressure, the ball detent (19) is forced out of the
way and/or the solenoid is deactivated thus allowing the spool (7)
to quickly shift open, delivering the compressed air energy to the
projectile (9). At or around this point, the motor (1) is reversed
to move the piston (5) back to its initial position.
[0072] Once the piston (5) has returned to its starting position,
the spool valve (7) can be shifted to the closed position by using
the solenoid (18). By waiting to shift the spool (7) until after
the piston (5) has returned, the retract does not create a vacuum
and can be done at very high speeds. Additionally, this allows use
of differential gearing for the advance and retract of the piston
(5) as shown in FIG. 3. It should be noted while a lead screw (4)
is described in this embodiment, substantially similar elements
which convert rotational motion to linear motion (i.e. a linear
motion converter) may work equally as well. Such elements could
include, but are not limited to, slider crank type mechanisms or
rack and pinion systems. Once the piston (5) has returned to its
starting point, the cycle is complete and the electric air gun is
now ready to initiate a repeat cycle.
[0073] A bolt is used in many air gun designs to chamber the
projectile. It can be either manually operated or automatically
operated. For automatic operation, the present invention preferably
uses a mechanical bolt link (15) to connect the bolt (6) to the
piston (5). Thus the motor (1) can be used to control the movement
of the bolt (6) which results in more efficient actuation. When the
piston (5) is at the end of its stroke, the bolt (6) is fully
forward and the projectile (9) is seated and ready to be fired. As
the piston (5) and bolt (6) retract, the bolt (6) opens the
projectile inlet port (16), as shown in FIG. 5, that allows the
next projectile to be moved from the projectile feeder (22) into
the barrel (8). This projectile (9) waits to be chambered by the
bolt (6) until the next firing cycle is started.
[0074] Due to the different loading requirements put on the motor
(1) for either the compression forward (compression cycle) or
return cycle, it is advantageous to have alternate coupling ratios
for connecting the motor (1) to the lead screw (4). The preferred
embodiment includes using planetary gears, direct drive features
and a set of clutches, as shown in FIG. 3. This results in the
preferred embodiment having a forward or compression drive at a 6:1
reduction ratio and a return ratio of 1:1. This is illustrated best
in FIG. 3. After power is applied to the motor (1) from the power
source (2), the motor shaft adapter (37) which is directly attached
to the motor (1) begins to turn. This begins turning the pinion
(36) which drives the planet gears (34). The planet gears (34) are
tied together through a planet gear carrier (32) and turn inside
the ring gear (33). The use of planetary gears allows for a very
robust drive system within a tight space and at a very economical
cost. The planet gear carrier (32) turns the planetary clutch (31)
which locks up and turns the lead screw shaft adapter (30). The
lead screw shaft adapter (30) is directly coupled to the lead screw
(4), not shown in FIG. 3. The reverse clutch (35) freeewheels in
this case and does not contribute to the output motion. For the
return cycle, the motor (1) reverses direction which causes the
planet gear carrier (32) to release the lead screw shaft adapter
(30). The motor output is directly coupled to the lead screw shaft
adapter (30) through the reverse clutch (35). This is a direct
drive coupling resulting in a much faster return and thus
increasing the firing rate capability of the electric air rifle. It
should be understood that it is possible to substitute alternative
coupling means such as pulleys, belts, and other clutching elements
such as mechanically shifted, wrap spring or electromagnetic
clutches and not depart from the spirit of the invention. It will
be further understood that different drive coupling ratios can be
chosen depending on the performance characteristics desired.
Further advantages of a different forward and reverse ratio include
the minimization of the stored kinetic energy thus softening the
end of stroke blow on the bumpers.
[0075] Although the solenoid (18) in this embodiment is an
electrical element, it is possible to use alternate means to reset
the spool (7) and not depart from the spirit of this invention. One
such alternate means is shown in FIG. 4. In FIG. 4, spool (7) is
forced open when the pressure in the cylinder (14) exceeds that
which is necessary to hold the ball detent (19) in the spool (7).
When that occurs, spool (7) slides open and allows the
high-pressure air to escape through the compressed air passageway
(13) on its way to the projectile (9) residing in the barrel (8).
Resetting the spool (7) is accomplished by pressurized air
delivered into the cylinder (14). This air can be made available by
using a return air shock created by the O-rings on piston (5) and
the back end of the cylinder (14), as shown in FIG. 5. A further
method of closing the spool (7) is to use a lost motion device
coupled to the piston (5) or bolt (6). The lost motion device could
be used to only allow the last 10% or so of piston or bolt movement
to reset the spool (7).
[0076] Additional techniques of controlling or retaining the spool
(7) would be apparent to one skilled in the art including: snap
acting elements in which the retention force is adjustable to allow
for adjustment of the projectile energy. The spool would fully open
at some predetermined force with a snap action. A key element in
all these designs includes shifting the spool from a fully closed
position to a fully open position in less then 100 milliseconds.
Furthermore, although the preferred embodiment employs a shiftable
spool, other valves including but not limited to ball, poppet, gate
and solenoid which meet this actuation requirement could be used
without departing from the spirit of the invention. By quickly
opening the valve, the energy is efficiently transmitted to the
projectile (9) resulting in a more energetic projectile.
[0077] The preferred invention includes additional enhancements
like end of stroke bumpers (17) or a return air shock (23), shown
in FIG. 5. These elements absorb excess kinetic energy which may be
available at the ends of the strokes of the piston (5). It is
preferred that the elements retain an elastic element so that the
excess energy can be recovered in a rebound thus increasing rates
of fire for high speed cycling.
[0078] In order to optimize the firing time of the compressed air
gun it may be advantageous to have the piston (5) preload the air
in the cylinder (14). This can be accomplished by advancing the
piston (5) from its starting point to pre-compress the air in the
cylinder (14). This would decrease the distance the piston (5)
would have to move before a shot could be fired creating a shorter
lock time. The cycle would start with the firing of the start
switch (10). The piston (5) would proceed to the end of the
cylinder (14), compress the air and fire the projectile (9). At the
end of the piston (5) stroke, the motor (1) would reverse direction
and fully retract the piston (5) to allow air to be replenished in
the cylinder (14). At this point the motor (1) would reverse again
and advance the piston (5) to pre compress the air in the cylinder
(14). The piston (5) would then stop and wait for the next pull of
the start switch (10). This would constitute a full cycle.
[0079] Although the preferred embodiment employs a linear
compressor described as a lead screw driven piston compressor, it
is understood that various other direct mechanical air compression
means such as linear compressors using bellows or rotary
compressors as in gear or screw compressors could be adapted to
operate in the previously described cyclic fashion without
departing from the spirit of this invention. These methods directly
compress the air as opposed to inefficient and complicated indirect
methods such as an electrically wound spring piston technique.
[0080] Furthermore, additional modifications are possible by those
skilled in the art including, fully automatic firing, burst mode
firing or two position triggers which allow for a pre-advancement
of the piston in readiness for the next shot.
[0081] Circuit Operation:
[0082] In the preferred embodiment, the control circuit includes a
microprocessor, high power switching elements for directing power
from the power source to the motor, at least one control circuit
input which could be from an internal or external timer or position
feedback element and an electronic trigger switch. Although these
elements are used in the preferred design, it is understood by
those familiar with the art that considerably simplification is
possible without departing from the spirit of the invention. A
cycle begins with the pressing of the start switch (10). Although
the power can be directed to the motor (1) through the start switch
(10), it is preferred if high power switching elements are used
such as MosFets or Relays. Additional advantages are available by
using switching elements including the ability to control the speed
of the motor (1). Once power is applied to the motor (1), the
piston (5) begins to advance via rotation of the lead screw (4).
The feedback elements are preferably used to determine the location
of the piston (5). The control circuit (3) can then make decisions
in regards to releasing the high-pressure air in the case of a
solenoid or other electromotive retention of the spool.
Additionally, this information can be used for reversing or
controlling power to the motor (1) depending on the type of
compressor used. At the end of a cycle, a further control circuit
input such as another sensor, pressure transducer or a timer may be
used to shut the power off from the motor and thus leave the
electric air gun ready for the next cycle.
[0083] An additional embodiment includes the use of storing a
number of start switch (10) pulls. This allows the gun to continue
cycling in a seamless fashion in the event the start switch is
actuated faster then the electrical projectile (9) launches can
occur. For example, two or more start switch pulls could be stored
thus allowing the user the ability to fire sequential shots in a
semiautomatic fashion without having to coordinate the shots with
the finish of a cycle in the electric air gun. A further embodiment
includes the ability to have a shot counter to warn the user when
less then a certain number of shots remain. For example, with a
power source (2) which is good for 300 shots, a warning light could
be illuminated when less then 25 shots remain. Further embodiments
involve the use of battery monitoring circuitry to ensure that the
user is warned when the power source (2) is low.
[0084] The preferred sensor locations include on the rotational
elements for the lead screw counter and on the piston (5) for a
position indicator. It is understood by those skilled in the art
that the sensors can be used in conjunction with circuit elements
to allow location at different places and that sensors can be of
many forms including but not limited to limit switches, hall effect
sensors, photosensors and reed switches without departing from the
spirit of the invention.
[0085] A further improvement in the electric air gun includes
routing at least a portion of the power through the start switch
(10) to allow cycling only if the start switch (10) is depressed.
To reduce contact wear, the control circuit (3) preferably
introduces a delay such that the high power is switched after the
start switch (10) is fully closed thus eliminating arcing.
* * * * *