US 2905149 A
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Description (OCR text may contain errors)
Filed March 28, 1957 Aw N ,IN VEN TOR. P065@ I. JWM/Sav 64@ :ffy/J@ ATTORNEV United States Patent ROTARY TOOL CONSTRUCTION Roger I. Swanson, Spring Lake, Mich., assignor to Gardner-Denver Company, Quincy, Ill., a corporation of Delaware Application March 28, 1957, Serial No. 649,183
6 Claims. (Cl. 121-11) This invention relates generally to portable hand held tools and more particularly to pneumatic tools driven by rotary motors of the sliding vane type.
In recent years, industry has become increasingly critical of the noise level of pressure uid operated tools particularly where many of these tools are in operation within an enclosure such as in modern assembly line factories. Accordingly, manufacturers of pneumatic tools have devised many novel devices to mule the sounds produced by these tools and by the air motors by which the tools are driven.
Accordingly, it is an object of this invention to provide a tool in which some of the objectionable noise emitted by an air motor of the sliding vane type is eliminated.
lt is a further object of this invention to provide a tool in which the interval of noise creation is reduced to an irreducible minimum in that the motor runs only when work is being done by the tool.
It is a still further object of this invention to further reduce the exhaust noise of the tool by conducting the exhaust air from the motor through certain of its operating or structural elements which serve as sound reducing or muiiling chambers.
Further objects and advantages of this invention will become apparent upon reading of the specification and accompanying drawing in which:
Fig. 1 is a transverse section of a pneumatic rotary tool constructed in accordance with this invention.
Until recently, it was generally accepted practice among pneumatic tool manufacturers in designing their tools to exhaust air from the air motor of the tool directly to atmosphere through slots in the housing of the tool surrounding the motor. This practice generally served to give maximum output to the motor by reducing the back pressure to a minimum. The current trend, however, is to conduct exhaust air through one or more muiing chambers or through muiling material before allowing the exhaust air to pass to atmosphere. Although the back pressure created by muffling of the exhaust affects the performance of the motor to some degree, this is considered secondary to the desirability of muilling the noise emitted by the tool.
It is also general practice among manufacturers of pneumatic tools to control the operation of the motor by a throttle valve between the source of supply and the motor of the tool, that is to say, the valve is normally on the upstream side of the motor. Motors of the sliding vane type emit an undesirable noise when the supply of air to the motor is interrupted. This noise which is generally of a higher pitch than the exhaust noise emitted during continuous operation of the tool is believed to be created by the rotor and vanes pumping the supply line and the exhaust chambers and alternately creating a vacuurn and a pressure in these areas of the tool as the motor decelerates. One of the features of the tool herein described is the provision of a valve on the exhaust or downstream side of the pneumatic motor which con- ICC trols the operation of the motor by choking the exhaust passage of the tool. With such a valve, the noise, previously described as occurring when the air supply to the motor is interrupted, is completely eliminated.
It has also been observed that in many assembly line uses of pneumatic tools for such purposes as driving screws and setting nuts that the operators of the tools hold the throttle valves open continuously. As the work piece comes to the operator the tool is applied to its Work. In most tools the pneumatic motor runs continuously even though the screw driving or nut setting tool itself may be driven through a clutch so that the output end of the tool is only driven when the tool engages its Work. In a large assembly operation where many tools are in use not only is a lot of unnecessary noise created but a large volume of compressed air is wasted needlessly. The rotational speed of most pneumatic screw drivers and nutsetters range from 500 to 3000 revolutions per minute, it is obvious that the actual time of performing a screw driving or nut setting operation is measured in seconds and more often in fractions of a second. Even in operations where the pneumatic tools are not run continuously it is common practice for the operators to start the tools as they move the tools toward the work and to hold the throttle even after the clutch has disengaged indicating that the Work of the tool has been completed. Therefore, another feature of this invention is the provision of means whereby the exhaust valve hereinbefore described is opened only when the tool engages its work.
With these primary features in mind, it will be obvious that the general noise level in a manufacturing or assembly area in which screw driving and nut setting tools are used can be substantially reduced by using tools constructed in accordance with this invention.
Referring now to the drawings, Fig. l shows a pneumatic nut setting tool generally indicated as 10 and comprising a housing 11 and a head 12. Within the housing 11 is a sliding vane type rotary motor 13 which drives a spindle 14 through a set of planetary gears 15.
Pressure lluid is supplied to the head 12 by a conduit 16 connected to a source of pressure fluid, not shown. A passage 17 in the head conducts the pressure uid to a passage 18 in the housing 11 and thence to the air motor 13. Exhaust air from the air motor is conducted from exhaust slots 19 through a passage 20 to the for- Ward end of the housing 11 where the air passes over the bearings and gears in the front of the tool. This area of the tool serves as a resonance or muling chamber for the exhaust air.
A throttle valve 21, within the head 12 in the passage 17, is shown as actuated by a control lever 22.. This valve is not necessary in the operation of the tool herein described because a choke valve on the exhaust side of the motor, to be described hereafter, actually controls the operation of the motor 13. However, in certain applications where additional control of the tool is desired the additional lever controlled throttle valve 21 may be used.
The spindle 14 is slidably connected to and serves to rotate a tool holder 23 in which a work contacting tool, here shown as a hex socket 24, is received. It might be noted at this point that the tool holder 23 may be constructed in two pieces so as to form a clutch between the spindle 14 and the work contacting tool 24. It will be noted that the socket 24 has an extension of reduced diameter 25 which is slidably received in a recess 26 in the spindle 14 and that a coiled spring 27 in the recess 26 urges the socket 24 towards the forward end of the tool against a resilient ring or washer 28. The ring 28 serving as a valve seat is retained within a cylindrical shell 29 having a port therethrough while the socket 24 acts as a valve to control the emission through said port of exhaust air from the tool housing to atmosphere.
In the operation of a tool embodying the features hereinbefore described, pressure iluid is admitted to the ,motor 13 by depressing the throttle lever 22 or, if no throttle valve is provided, air may be continuously present at the motor. However, since the air cannot pass to atmosphere because of the closed exhaust valve 24, the motor will remain inoperative. The tool is then manually positioned to its work and by exerting enough axial force of the tool against its work the socket or valve 24 is moved against the spring 27, the exhaust valve is thus opened permitting the motor to run until the tool is removed or the nut becomes so tight that the motorA 13 stalls. Upon removing the tool from the work the valve 24 will close, interrupting the operation of the motor.
The above described structure provides an extremely quiet running pneumatic tool which is operative only when there is work to be performed. The combination described lessens noise of operation by first, shortening the internal of motor operation; secondly, passing the exhaust from the motor through the forward gear housing which serves as a reasonance chamber; and thirdly, by eliminating the deceleration noise which occurs when motor operation is controlled solely by a throttle valve on the up-stream side of the motor.
An additional advantage of the structure shown is the presence of air at the forward end of the tool which can be used as a source of supply for a signal or timing device, a suction venturi, or power source for auxiliary devices. This feature is novel to this construction in that the source of air at this point may be continuous or controllable independently of the operation of the motor by lever 22 and throttle valve 21 with available pressures from full line pressure when the motor is not running to exhaust or near atmospheric pressure when the motor is running.
It will be obvious to one skilled in the artof pneumatics and pneumatic motors, that the above invention lends itself to variations and modiiications which will fall within the scope of the invention claimed.
I claim as my invention:
l. In a pressure fluid operated tool having avane type rotary motor, a chamber into which exhaust from said motor is received, a valve controlling the flow of pressure fluid from said chamber to atmosphere, said valve being responsive to axial pressure of said tool against a work piece.
2. A portable pressure fluid operated tool comprising, in combination, a housing containing a motor Vand a spindle driven by said motor, a Work engaging tool element resiliently mounted With respect t said ,spindle and driven thereby; a valve seat in the forward end of said housing, said tool element normally engaging said seat v 4 to prevent the exhausting of spent pressure iiuid from said motor to atmosphere.
3. A portable pressure uid operated tool comprising, a motor, a spindle driven by said motor, a chamber into which exhaust from said motor is received, a work engaging tool element within said chamber, said tool element coacting with a port in an end wall of said chamber to form a valve; resilient means normally holding said valve closed to prevent the discharge of pressure fluid from said chamber.
4. In a portable pressure fluid operated tool, a housing having two chambers therein, a rotary motor in one chamber; means for conducting spent pressure uid from said motor to a second chamber; a spindle within said second chamber and driven by said motor, a Work engaging member driven by said spindle within said second chamber, resilient means urging said work engaging member against a port in said second chamber preventing the passage of pressure iluid lfrom said chamber, said work engaging member being adapted to open said port in response to axial pressure on said member whereby to permit spent pressure fluid in said second chamber to pass to atmosphere.
5. In a portable pressure Huid operated tool, a housing having two chambers therein, a sliding vane type rotary motor in one chamber; a passage whereby spent pressure iiuid from said motor is conducted to a second chamber; a port in said second chamber; a work engaging member driven by saidr motor within said second chamber, said work engaging member yieldably closing said port and adapted to open said port to permit the flow of pressure ud from said second chamber in response to axial pressure on said member.
6, In a pressure fluid operated tool: a housing; a motor therein exhausting into said housing; a fluid intake for said motor; a tool element mounted in said housing and driven by said motor; said housing having an opening through which said tool element extends; and said tool element and said opening detning valve means for controlling the discharge of motor exhaust iluid from said housing.
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