Patent Application
20090152319
The present invention relates generally to compact or handheld pneumatic tools. More particularly described, the present invention relates to an improved pneumatic tool design for generating increased power and improved performance.
Pneumatic tools, or air tools, are typically powered by gas, such as compressed air or compressed carbon dioxide. A compact “pistol grip” pneumatic tool configuration generally resembles the shape of a pistol. That is, a pistol grip pneumatic tool includes a handle that is generally perpendicular to the tool head and a trigger mechanism disposed on the handle. Common pistol grip pneumatic tools include handheld drills, sanders, nail guns, nut runners, etc. A compact “inline” pneumatic tool configuration generally includes a handle that is parallel to the tool head, with a trigger mechanism disposed on the handle. Common inline pneumatic tools include drills, grinders, nut runners, etc.
In a conventional pneumatic tool design, compressed air is forced into a pneumatic motor chamber, causing a turbine therein to spin and power a drive shaft, plunger or other actuator. However, in conventional pneumatic tool designs, the motor inlet that allows compressed air to enter the pneumatic motor chamber is disposed in an end plate at the rear of the pneumatic motor chamber. This location is a limiting factor in the size of the motor inlet. In particular, if the motor inlet is too large or too small, the compressed air will not properly engage the turbine inside the pneumatic motor chamber. Further, because the air inlet chamber which leads to the motor inlet is positioned behind the end plate of the pneumatic motor chamber in the conventional design, the size of the pneumatic motor chamber is necessarily limited by the form factor of the tool. To accommodate a larger pneumatic motor, the overall size of the tool would need to be increased. Accordingly, there exists a need in the art for a pneumatic tool design that allows a greater variation in the size of the motor inlet through which compressed enters the pneumatic motor. Further, there exists a need in the art for a pneumatic tool that maximizes the size of the pneumatic motor chamber without increasing the overall size of the pneumatic tool.
The present invention meets the aforementioned need in the art by providing an improved pneumatic tool design. The pneumatic tool design may be applied to a pistol grip or inline pneumatic tool. The improved design includes a pneumatic motor chamber for housing a turbine. The pneumatic motor chamber has at least a first side wall, a second side wall and a rear end plate. The improved design includes an air path for directing compressed air into and through the pneumatic motor chamber. The air path includes an air inlet chamber that at least partially surrounds the pneumatic motor chamber, a motor inlet disposed in the first side wall of the pneumatic motor chamber and at least one exhaust port disposed in the second side wall of the pneumatic motor chamber. For example, the motor inlet may be disposed in the top wall of the pneumatic motor chamber and the exhaust port may be disposed in the bottom wall of the pneumatic motor chamber. Alternatively, the motor inlet may be disposed in the bottom wall of the pneumatic motor chamber and the exhaust port may be disposed in the top wall of the pneumatic motor chamber. A seal surrounds the pneumatic motor chamber and isolates the motor inlet, which is thus at a rear outer portion of the pneumatic chamber, from a forward outer portion of the pneumatic motor chamber. The seal may be, for example, an o-ring or another suitable sealing member.
The present invention provides an improved pneumatic tool design, which includes an air path that at least partially surrounds the circumference of a rear outer portion of a pneumatic motor chamber. This air path is separated from a forward outer portion of the pneumatic motor chamber by a seal. The air path includes a motor inlet that may be positioned along the top, bottom or a side of the pneumatic motor chamber between the high-pressure seal and the rear end plate of the pneumatic motor chamber. According to the inventive design, the size of the motor inlet can be larger than in conventional pneumatic tool designs. Furthermore, because the motor inlet is not positioned behind the pneumatic motor chamber, the size of the pneumatic motor chamber can be increased without substantially increasing the overall dimensions of the pneumatic tool. Referring to the drawings, in which like numerals represent like elements throughout the several figures, aspects of the present invention will be described in the context of
The air inlet chamber 125 extends up the inside of the handle 107 behind a pneumatic motor chamber 135. After the compressed air enters the inlet chamber 125, according to
Accordingly, as illustrated in
As shown in
As illustrated in
Once the compressed air enters the pneumatic motor chamber 235, it spins a turbine 260, which in turn powers a drive shaft 240. The drive shaft 240 actuates a tool head, such as a drill bit or a nut runner. In other types of power tools, the turbine 260 may be used to power other types of actuators. For example, the turbine 260 may power a means for rotating a sanding belt in a pneumatic sander or a plunger for driving a nail in a pneumatic nail gun. In the illustrated exemplary embodiment, the motor inlet 230 is located in the top wall of the pneumatic motor chamber 235 between the end plate 232 and the seal 250. In alternative embodiments, however, the motor inlet 230 may be disposed in the bottom wall or a different side wall of the pneumatic motor chamber 235 between the end plate 232 and the seal 250. In embodiments where the motor inlet 230 is disposed in the bottom wall of the pneumatic motor chamber 235, an additional improvement in power and performance may be achieved by confining the compressed air flow to a substantially linear path prior to its entering the pneumatic motor chamber 235.
Extending the air inlet chamber 225 around the side of the pneumatic motor chamber 235 and positioning the motor inlet 230 on the top (or bottom or side) wall thereof, allows the motor inlet 230 to be larger than in a conventional pneumatic tool design 100. Specifically, the direction of the air flow and the curved portion of the air inlet chamber 125 provide a rotational bias to the compressed air as it enters the motor inlet 230, thereby causing the compressed air to properly engage the turbine 260, even when the size of the motor inlet 230 is increased. Increasing the volume of air entering the pneumatic motor chamber 235 can result in increased horsepower generated by the pneumatic motor. Further, because the motor inlet 230 is disposed on the top (or bottom or side) wall of the pneumatic motor chamber 235—as opposed to behind the rear end plate 232—the pneumatic motor chamber 235 can be extended lengthwise without increasing the length of the upper tool housing 202 or the overall dimensions of the tool. This increase in size of the pneumatic motor chamber 235 can accommodate a larger pneumatic motor capable of generating increased horsepower. Further, in the event the pneumatic motor chamber 235 is not lengthened, the length of the upper tool housing 202 (and thus the overall dimensions of the tool) can be reduced without a loss of horsepower.
As illustrated in
The improved pneumatic tool design 200 of the present invention provides superior performance over a conventional pneumatic tool design 100. In particular, the improved pneumatic tool design 200 can accommodate a larger motor inlet 230, which allows a greater volume of compressed air to engage the turbines 260 that power the tool. Further, the improved pneumatic tool design 200 can accommodate a larger pneumatic motor chamber 235 without requiring a change to the overall form factor of the tool. By way of example, the horsepower generated by two commercially-available pistol grip pneumatic power drills, the ATLAS COPCO LBB36 and the DOTCO 14CNL, was compared to the horsepower generated by a pneumatic power drill according to the present invention. For purposes of the comparison, the pistol grip pneumatic power drill according to the present invention was designed with substantially the same overall dimensions as the commercially-available pneumatic power drills, and all three tools were connected to the same air compressor. However, the inventive pistol grip pneumatic power drill design was able to accommodate a larger, more powerful motor. The results of the comparison are presented in Table 1 below, which shows that the inventive pneumatic drill exhibited a substantial increase in horsepower over the two conventional pneumatic drills of approximately the same size. In fact, the inventive pneumatic drill generated almost double the horsepower of the conventional tools.
Based on the foregoing, it will be understood that the improved pneumatic tool design of the present invention offers many advantages over conventional pneumatic tool designs. While certain exemplary embodiments of the present invention have been shown and described herein, it will be evident to those of ordinary skill in the art that various modifications and changes may be made thereto without departing from the spirit and the scope of the present invention as set forth herein. It should be appreciated, therefore, that aspects of the present invention were described above by way of example only and are not intended as required or essential elements of the invention unless explicitly stated otherwise.
