The present invention generally relates to pneumatic tools and more particularly to a pneumatic nailer.
Pneumatic tools are commonly used in the construction industry. In particular, pneumatic nailers are regularly used in roofing and framing projects. In a standard setting, a pneumatic nailer is coupled to a source of high pressure air, e.g., a portable compressor, to supply the pneumatic nailer with a source of pressure regulated compressed air. The pneumatic nailer is usually equipped with an elongated magazine that holds a plurality of nails. The nails are usually available in strips, whereby the nails are uniformly spaced apart from each other and are loosely connected to each other by a clip made from a thin layer of plastic or paper, or are simply connected to each other by a resin-type material. In another form, the nails are provided in a coil that is insertable into a round magazine. Once a worker at the construction site places a strip of nails into the magazine and couples the nailer to the high pressure source, the nailer is ready for operation.
The pneumatic nailer is equipped with an ejector assembly which includes a spring loaded safety tip. A nail from the strip of nails that is placed inside the magazine is internally situated adjacent to the tip of the ejector assembly. The operator places the tip of the ejector assembly against a workpiece to depress the tip. Once the tip is depressed, the nailer becomes responsive to force applied to a trigger. When force is applied to the trigger by the operator, the nailer activates a pneumatic actuating mechanism inside the nailer. The pneumatic actuating mechanism includes a ramming member which is plunged at a high velocity toward the nail from a ready position. The ramming member strikes the nail causing the nail to disengage from the strip of nails, exit through the ejector assembly, and drive into the workpiece. Once the operator releases the trigger, the pneumatic actuating mechanism quickly returns the ramming member to the ready position, and remains there until force is again applied to the trigger by the operator.
During the above operation, the nailers of the prior art provide compressed air to several chambers in order to activate the actuating mechanism as well as to return the actuating mechanism to its ready position. The compressed air is often released to atmosphere after it has performed its intended purpose, e.g., activate the actuating mechanism or return the ramming member. Therefore, several volumes of compressed air perform mechanical work in respective chambers, before being released to atmosphere. As a result, the compressed air leads to power cycling of the compressor, which not only uses power but also shortens the life of the compressor. In addition, some prior art nailers include return mechanisms which are relatively slow to return the ramming member to its ready position. This results in slower tool speed.
Therefore, there is a need for a pneumatic nailer that can recycle compressed air for performing some of its functions during activation of its actuating mechanism and returning the actuating mechanism to the ready position responsive to the worker pulling and releasing the trigger. There is also a need to improve the speed at which the ramming member is returned to the ready position, which would result in faster tool speed.
In accordance with one embodiment of the present disclosure there is provided a pneumatic nailer for use with a high pressure fluid source. The pneumatic nailer includes a housing defining a storage chamber positionable in fluid communication with the high pressure fluid source, a cylinder positioned within said housing. The pneumatic nailer further includes a piston having a piston head and a driver member extending from said piston head, said piston head being movable within said cylinder, said cylinder and said piston head defining (i) a displacement chamber on a first side of said piston head, and (ii) a return chamber on an opposite second side of said piston head. The pneumatic nailer also includes a sleeve movable with respect to said cylinder between a first sleeve position and a second sleeve position, said sleeve and said cylinder defining a sleeve space therebetween, wherein, when said sleeve is positioned in said first sleeve position, (i) said sleeve space is isolated from fluid communication with said return chamber, and (ii) said return chamber is positioned in fluid communication with atmosphere, and wherein, when said sleeve is positioned in said second sleeve position, (i) said sleeve space is positioned in fluid communication with said return chamber via, and (ii) said return chamber is isolated from fluid communication with atmosphere. Furthermore, the pneumatic nailer includes a valve movable between (i) a first valve state in which said displacement chamber is isolated from fluid communication with said storage chamber and positioned in fluid communication with atmosphere, and (ii) a second valve state in which said displacement chamber is positioned in fluid communication with said storage chamber and isolated from fluid communication with atmosphere. The pneumatic nailer also includes an actuator positionable between an actuated position and a deactuated position, wherein (i) when said actuator is positioned in said actuated position, said valve is caused to move to said first valve state and said sleeve is caused to move to said first sleeve position, and (ii) when said actuator is positioned in said deactuated position, said valve is caused to move to said second valve state and said sleeve is caused to move to said second sleeve position.
The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one of ordinary skill in the art to which this invention pertains.
Referring to
A high pressure fluid source FS, such as a portable air compressor, includes a coupling member (not shown) that cooperates with the coupling member 103 so as to place the high pressure fluid source FS in fluid communication with the pneumatic nailer 100. The compressed air coupling member 103 is disposed at an end of the handle 105 and is in continuous fluid communication with the storage chamber 122. The storage chamber 122 internally extends from a cavity in the handle 105 to a cavity adjacent to the cylinder 108. The trigger 104 is positionable in two positions. The first position is referred to as an actuated position and the second position is referred to as a deactuated position. The trigger valve 106 is also positionable in an actuated position and in a deactuated position. The trigger 104 is biased by a spring 107 to urge toward the deactuated position. Movement of the trigger 104 from its deactuated position to its actuated position causes the trigger valve 106 to move from its deactuated position to its actuated position.
The trigger valve 106 is in fluid communication with the sleeve chamber 118 and the main valve chamber 120. The sleeve chamber 118 and the main valve chamber 120 are in continuous fluid communication with each other. In the actuated position of the trigger valve 106, the trigger valve 106 is positioned to place the combination of sleeve chamber 118 and the main valve chamber 120 in fluid communication with atmosphere, i.e., allows fluid that is held in these chambers to escape to atmosphere thereby equalizing the pressure in these chambers with atmospheric pressure. In contrast, in the deactuated position, the trigger valve 106 is positioned to place the combination of sleeve chamber 118 and the main valve chamber 120 in fluid communication with the storage chamber 122. The piston 110 includes a piston head 111 and a drive member 113 that is coupled to the piston head 111. The main valve 112 includes the fluid passage 136 which is centrally located in the main valve 112. The main valve also includes sealing members 150 and 152.
The cylinder 108 is fixedly disposed inside the housing 102. The piston head 111 is moveably disposed inside the cylinder 108. The main valve 112 is moveably disposed inside a back portion of the housing 102. The sealing member 152 is disposed around the main valve 112 and seals the valve against the housing 102.
The main valve 112 is configured to move from a first position to a second position. In the first position, referred to as a deactuated position, the main valve 112 is in contact with the cylinder 108, and thereby seals the cylinder from fluid communication with the storage chamber 122 with the sealing member 150. The deactuated position of the main valve 112 is depicted in
The main valve 112 has two opposing activation surfaces 112A and 112B. The activation surface 112A is in continuous fluid communication with the main valve chamber 120. The activation surface 112B is in continuous fluid communication with the storage chamber 122. The activation surface 112A is larger in area than the activation surface 112B. When the main valve chamber 120 is in fluid communication with atmosphere, i.e., when the trigger valve 106 is in the actuated position, a negligible force is acting on the activation surface 112A. Meanwhile, a force F112B, i.e., pressure inside the storage chamber multiplied by the area of the activation surface 112B, is acting on the activation surface 112B in a direction of the arrow B. The force F112B causes the main valve 112 to move in the direction of the arrow B. When the main valve chamber 120 is in fluid communication with the storage chamber 122, i.e., when the trigger valve 106 is in the deactuated position, a force F112A, i.e., pressure inside the main valve chamber 120 multiplied by the area of the activation surface 112A, is acting on the activation surface 112A in the direction of an arrow A. The same force F112B is continuing to act on the activation surface 112B in the direction of the arrow B. However, since the activation surface 112A is larger than the activation surface 112B, the force F112A is also larger than the force F112B. The difference between the two forces F112A and F112B results in a net force F112N with a magnitude of F112A-F112B and a direction in the direction of the arrow A. Therefore, the net force F112N causes the main valve 112 to move in the direction of the arrow A.
In addition, a biasing member (not shown) is also disposed between the main valve 112 (contacting the activation surface 112A) and the end portion of the housing. The main valve biasing member is configured to provide an additional force F112S in the direction of the arrow A to add to the force F112A. The force F112S is significantly smaller than the force F112B, thereby the compressed air in the storage chamber can easily overcome the force F112S when the force F112A is negligible. In addition, the main valve biasing member biases the main valve 112 into contact with the cylinder to prevent rattling of the main valve 112 when there is no pressure applied to the pneumatic nailer 100, e.g., during shipping of the nailer.
The displacement chamber 128 is a space defined between the piston head 111 and the main valve 112. In
The sleeve 114 is moveably disposed outside of the cylinder 108 and is configured to form a sleeve space 124 between the sleeve 114 and the cylinder 108. The sleeve 114 includes sealing members 154, 156, and 158 to seal the sleeve chamber 118 from the sleeve space 124 as well as from the vent ports 132. The sleeve is biased in the direction of the arrow B by the biasing member 116. The sleeve 114 is configured to move from a first position to a second position.
In the first position, referred to as a deactuated position, the sleeve 114 is at a distal end of the housing 102. The deactuated position of the sleeve 114 is depicted in
The second position, referred to as an actuated position, is defined by the sleeve 114 after it is moved in the direction of the arrow B. In the actuated position, the sleeve chamber 118 is no longer in fluid communication with the storage chamber 122. Instead, the sleeve chamber 118 is in fluid communication with atmosphere. The biasing force F114S is larger than the Force F114A, which is negligible in the actuated position. Therefore, the sleeve 114 moves from its deactuated position to its actuated position in the direction of the arrow B. In the actuated position, the sleeve space 124 is in fluid communication with the displacement chamber 128 via check valves 130, as discussed below in more detail.
In operation, the main valve biasing member (not shown) biases the main valve 112 against the cylinder 108. An operator couples the pneumatic nailer 100 to a high pressure source, e.g., a compressor, by connecting the compressed air coupling member 103 to the coupling member (not shown) of the high pressure fluid source FS. So coupled, compressed air advances into the storage chamber 122. With the trigger 104 being in the deactuated position, the trigger valve 106 is positioned to place the main valve chamber 120 in fluid communication with the storage chamber 122. The pressure in the main valve chamber 120 generates the force F112A on the activation surface 112A of the main valve 112. Also, the pressure in the storage chamber 122 generates the force F112B on the activation surface 112A of the main valve 112. The force F112A and the force F112S, i.e., the force generated by the main valve biasing member (not shown), counteract the force F112B to generate the net force F112N which causes the main valve 112 to forcefully remain against the cylinder 108.
Also, with the trigger being in the deactuated position, the trigger valve 106 is positioned to place the sleeve chamber 118 in fluid communication with the storage chamber 122. The pressure in the sleeve chamber 118 generates the force F114A on the activation surface 114A of the sleeve 114. The force F114A counteracts the force F114S to generate the net force F114N which causes the sleeve 114 to assume the position shown in
The operator then presses on the trigger 104 to move it to the actuated position.
Once the main valve 112 no longer seals the cylinder 108 from the storage chamber 122, high pressure fluid from the storage chamber 122 is advanced into the displacement chamber 128. In turn, the piston 110 moves in the direction of the arrow A.
With the trigger being in the actuated position, the trigger valve 106 is positioned to place the sleeve chamber 118 also in fluid communication with atmosphere. Thereafter, the force F114A on the activation surface 114A of the sleeve 114 is negligible. The essentially unimpeded force F114S causes the sleeve 114 to move in the direction of the arrow B to its actuated position, as shown in
In the actuated position of the sleeve 114, the bidirectional ports 134 are in fluid communication with atmosphere via the vent ports 132. It should be appreciated that while two vent ports 132 and two bidirectional ports 134 are depicted in the figures of the present disclosure, additional bidirectional ports and vent ports can be provided to improve fluid communication.
With the bidirectional ports 134 being in fluid communication with atmosphere via the vent ports 132, the fluid present in the return chamber 126 is exhausted to atmosphere, as the piston 110 moves in the direction of the arrow A. The fluid transfer between the return chamber 126 and atmosphere is indicated by dotted arrows showing the direction of flow of the fluid. Since the return chamber 126 is in fluid communication with atmosphere, the piston 110 moves in an essentially unimpeded manner thereby improving the operational efficiency of the pneumatic nailer 100.
Also depicted in
With the trigger in the actuated position, the piston 110 continues to move in the direction of the arrow A from its position shown in
Also depicted in
Once the main valve 112 seals the cylinder 108 from the storage chamber 122, the displacement chamber 128 is placed in fluid communication with atmosphere via the fluid passage 136 located centrally in the main valve 112. In other words, with the main valve 112 placed in the position depicted in
With the trigger placed in the deactuated position, the trigger valve 106 is positioned to place the sleeve chamber 118 also in fluid communication with the storage chamber 122. Therefore, the force F114A on the activation surface 114A of the sleeve 114 overcomes the force F114S and causes the sleeve to move in the direction of the arrow A, to its position depicted in
In the deactuated position of the sleeve 114, the bidirectional ports 134 are in fluid communication with the sleeve space 124. Therefore, the return chamber 126, depicted as collapsed in
With the return chamber 126 being in fluid communication with the sleeve space 124, and with the displacement chamber 128 being in fluid communication with atmosphere via the fluid passage 136, the high pressure fluid present in the sleeve space 124 causes the piston to move in the direction of the arrow B.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.
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