US 20050188974 A1
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.
1. A compressed air gun for firing a projectile, comprising:
a bolt moveable from a first position to a second position for chambering at least one projectile;
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.
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9. A compressed air gun for firing a projectile, comprising:
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.
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17. A compressor apparatus for a compressed air gun, comprising:
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.
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.
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.
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.
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.
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.
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.
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.
All of the currently available devices suffer from a number of disadvantages, some of which include:
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:
Further objects and advantages will become more apparent from a consideration of the ensuing detailed description and drawings.
Reference numbers for the drawings are shown below.
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.
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
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
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
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
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.
The preferred invention includes additional enhancements like end of stroke bumpers (17) or a return air shock (23), shown in
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.
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.
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.
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.
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.
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.
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.