Tool driving or impacting – Automatic control of power operated means – Drive means responsive to torque or speed condition
Reexamination Certificate
2001-11-14
2002-10-08
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Automatic control of power operated means
Drive means responsive to torque or speed condition
C173S002000, C173S181000
Reexamination Certificate
active
06460629
ABSTRACT:
FIELD OF THE INVENTION
The present application relates to a pneumatic tool for applying torque to fasteners and a system incorporating such a tool.
BACKGROUND AND SUMMARY OF THE INVENTION
The use of pneumatic tools, such nutrunners and torque wrenches, for tightening fasteners is well-known in the art. In some systems, these tools are communicated to a processor that monitors the operating condition of the tool to determine whether the tool has properly completed a fastening job. Specifically, the processor determines whether the fastener has been tightened to a pre-set amount of torque. If the processor determines that the tool has not properly completed a fastening job, then the processor generates a visual or audible signal to the user indicating that the job was not completed. Also, the processor may log the event along with vehicle identification information into a computer readable memory (either in the processor itself or at a remote location) so that the inspection and full tightening of the incompleted fastener can be accomplished at a later time.
In one conventional arrangement, one end of a length of pneumatic tubing is communicated to the interior of the tool. The opposite end of the tubing is communicated to a transducer located inside the processor. As pressures vary inside the tool, these pressure variations are transmitted to the transducer via the pneumatic tubing. The transducer in turn converts these pressure variations into electric signals, which the processor processes to accomplish monitoring of the tool performance. This conventional arrangement suffers from two significant drawbacks. First, the tubing must be sufficiently long to enable the user to maneuver while using the tool. As a result of using a long length of tubing, the system will lose its signal integrity. Specifically, the signal's timing will be delayed because the signal must travel along the air within the tubing. Also, the signal will lose some of its strength because the air in the tubing is compressible. Second, the system will not function if the user steps on the tubing or the tubing becomes severely kinked because the pressure variations will not be effectively communicated to the processor's transducer.
U.S. Pat. No. 5,898,379 to Vanbergeijk, issued Apr. 27, 1999 (the '379 patent) discloses a system that allows for monitoring of the tool performance without the use of the pneumatic tubing. The tool disclosed in the '379 patent has a pair of pressure sensors and an on-board wireless transmitter that transmits a signal to a remote wireless receiver within the processor. A significant drawback of the subject matter disclosed in the '379 patent is that it fails to disclose an adequate sensing mechanism for sensing pressure variations within the tool. Specifically, the '379 patent discloses pneumatic pressure valves or switch contacts connected to moving mechanical components as being options for the pressure sensors. The interior of a pneumatic tool, however, is usually lubricated with oil or some other lubricant to improve performance and increase its operational longevity. The use of lubricant can interfere with the operation of either of the pressure sensing mechanisms disclosed in the '379 patent. For example, dirt or particles within the oil can build up on the pneumatic pressure valve, thus interfering with its performance. Likewise, lubricant present on the contacts of the switches can interfere with the proper operation of the switch. Specifically, the lubricant can interrupt the contact between the switch contacts, thus preventing the processor from determining that the switch is closed.
Consequently, there exists a need in the art for a pneumatic tool and system that has an improved pressure sensing system that is able to operate effectively in the presence of lubricants that are present within the tool.
To meet the foregoing need, one aspect of the present invention provides a pneumatically drivable tool for applying torque to fasteners in conjunction with (i) a processor that monitor the state changes of first and second switches on the tool during the performance of a fastening job and to compare the state changes to pre-selected parameters to determine a status of the fastening job and (ii) a supply of pressurized gas. The tool comprises a housing having a fluid path provided therein. The fluid path has an inlet end connectable to a supply of pressurized gas and an outlet end for exhausting the pressurized gas from the housing. A rotatable fastener engaging member is constructed and arranged to be engaged with a fastener in a torque transmitting relation wherein rotation of the fastener engaging member applies torque to the fastener to affect rotation of the fastener. A pneumatically drivable motor is positioned within the fluid path between the inlet and outlet ends. The motor is constructed and arranged such that the pressurized gas flowing through the fluid path flows through the motor to generate rotational power. The motor is operatively connected with the fastener engaging member such that the motor rotates the fastener engaging member using power generated by the pressurized gas flowing therethrough.
An actuator valve is positioned within the fluid path between the inlet port and the motor. The actuator valve is movable between an open position enabling the pressurized gas to flow through the path and a closed position preventing the pressurized gas from flowing through the path. An actuator is constructed and arranged to be manually operated by a user of the tool. The actuator is connected to the actuator valve such that operation thereof by the user moves the actuator valve between the closed and open positions thereof. A shut-off valve is positioned within the fluid path between the actuator valve and the motor and moves between an open position enabling the pressurized gas to flow through the path and a closed position preventing the pressurized gas from flowing through the path. A shut-off mechanism is coupled to the shut-off valve and provides for movement of the shut-off valve from the open position thereof to the closed position thereof responsive to the torsional resistance being offered by a fastener during rotation thereof reaching a predetermined level. A first switch having a plurality of states is adapted to be communicated with the processor to enable the processor to monitor states changes of the first switch. The first switch changes from a first of the states to a second of the states responsive to the pressurized gas flowing into a portion of the fluid path between the shut-off and actuator valves as a result of the actuator valve being in the open position thereof. A second switch having a plurality of states is adapted to be communicated with the processor to enable the processor to monitor states changes of the second switch. The second switch changes from a first of the states to a second of the states responsive to the pressurized gas flowing into a portion of the fluid path between the shut-off valve and the motor as a result of both the shut-off and actuator valves being in the open positions thereof.
Fluidly sealed casing structure encasing the first and second switches to protect the switches from any lubricant present within the housing. The use of the fluidly sealed casing structure enables the switches to function without interference from the lubricant in the tool. Preferably, the switches have their own casing; but alternatively they may both be encased in a fluid casing structure.
A related aspect of the invention provides a system incorporating the above-described tool.
Another drawback with conventional arrangements wherein pneumatic tubing is communicated between the tool and the processor is that the signaling device responsible for signaling the user that the job has not been properly completed is located on the processor. Typically, the signaling device is in the form of a flashing or steady state light. The user of the tool must look to the processor after completing each and every fasteni
Bookshar Duane R.
Juliano Michael
Steverding James F
Pillsbury & Winthrop LLP
Smith Scott A.
The Stanley Works
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