Power tool having proportioning transmission

Claim 2

A power tool for setting fasteners to a specified torque comprising a motor having a rotary drive and adapted to be energized to rotate the rotary drive at a specified free-running no-load speed and with a drive torque which increases as the rotary drive speed decreases from said no-load speed, a rotary output for setting fasteners, and unloaded torsion spring means interconnecting the rotary drive and rotary output for driving the rotary output, the torsion spring means having resistance to torsional deflection which increases with deflection and being operable to be angularly deflectEd continually and unrestrictively from its unloaded condition to provide for smooth deceleration of the rotary drive by the rotary output from its free-running no-load speed with the motor remaining energized.

Claim 3

The power tool of claim 1 wherein the motor is a rotary fluid motor set to stall or shut off at said specified torque, and wherein the spring means has a spring rate sufficient to decelerate the fluid motor to stall or shut off in approximately eight motor revolutions upon instantaneous arrest of the rotary output from free-running no-load speed.

Claim 4

The power tool of claim 1 further including torque indicating means operable in response to loading of the spring means for indicating applied fastener torque.

Claim 5

The power tool of claim 1 wherein the spring means is a helical torsion coil spring having opposite ends drivingly connected to the rotary drive and the rotary output and its coils positioned therebetween with freedom of movement for unrestricted axial deflection and radial contraction responsive to loading.

Claim 6

The power tool of claim 1 wherein the spring means has a spring rate sufficient to decelerate the rotary drive when the rotary output is arrested without further angular movement from free-running no-load speed while limiting peak applied fastener torque during such deceleration to a magnitude less than 125 percent of said specified torque.

Claim 7

The power tool of claim 1 further including selectively operative signal means for indicating an acceptable torque range, and a torque sensing device controlling operation of the signal means responsive to relative rotation between the rotary drive and the rotary output.

Claim 8

The power tool of claim 1 wherein the torsion spring means is active under running load conditions and has a spring rate sufficient to decelerate the motor when the rotary output is instantaneously arrested from free-running no-load speed while limiting peak applied fastener torque during such deceleration to a magnitude less than 125 percent of said specified torque.

Claim 9

The power tool of claim 1 further including a torque indicator for indicating peak applied fastener torque, and a torque sensing device for actuating the torque indicator, the torque sensing device being movable responsive to relative relation between the rotary drive and the rotary output.

Claim 10

The power tool of claim 8 wherein the torque indicator is operable under running load conditions and provides a continuous monitor of applied fastener torque.

Claim 11

The power tool of claim 1 wherein the torsion spring means has a spring rate sufficient to decelerate the rotary drive throughout the full range of running load conditions, and wherein the torsion spring means is operable for applying a relatively constant peak applied fastener torque irrespective of the deceleration rate of the rotary output due to fastener resistance to torque loading.

Claim 12

The power tool of claim 10 wherein said peak applied fastener torque exceeds said specified torque to an extent approximately equal to the maximum inertial torque transmitted from the rotary drive to the rotary output, and wherein torsional deflection of the torsion spring means is coincident with initial fastener torque loading for minimizing the magnitude of the transmitted inertial torque.

Claim 13

The power tool of claim 10 wherein the torsion spring means limits said peak applied fastener torque to a magnitude less than 125 percent of said specified torque.

Claim 14

A power tool useable in setting fasteners to a predetermined full fastener load and comprising power operated rotary drive means, rotary output means for setting fasteners, and a transmission including torsion spring means coupling the drive means to the output means, the torsion spring means being active under running load conditions and continuously maintaining a resilient driving connection between the drive means and the output means under running load conditions irrespective of the magnitude of peak applieD fastener torque, the transmission including a helical cam member connected to one of the drive means and output means, a linearly movable cam follower in camming engagement with the helical cam, member and a follower guide member supported on the other of the drive means and output means, the helical cam and follower guide members being relatively rotatable, and the cam follower being operative for sensing torque applied by the torsion spring means upon rotation of the drive means relative to the output means as indicated by linear movement of the cam follower.

Claim 15

A power tool useable in setting fasteners to a predetermined full fastener load and comprising power operated rotary drive means, rotary output means for setting fasteners, and a transmission including torsion spring means coupling the drive means to the output means, the torsion spring means being active under running load conditions and continuously maintaining a resilient driving connection between the drive means and the output means under running load conditions irrespective of the magnitude of peak applieD fastener torque, the transmission including a helical cam member connected to one of the drive means and output means, a linearly movable cam follower in camming engagement with the helical cam, member and a follower guide member supported on the other of the drive means and output means, the helical cam and follower guide members being relatively rotatable, and the cam follower being operative for sensing torque applied by the torsion spring means upon rotation of the drive means relative to the output means as indicated by linear movement of the cam follower.

Claim 16

The power tool of claim 13 further including display means operated by the cam follower for providing a visual indication of the torque applied by the spring means.

Claim 17

The power tool of claim 13 further including a transmission housing, the drive means and the output means being substantially aligned for rotation about a common axis, and fastener torque indicating means including a resettable marker supported for movement on the housing responsive to movement of the cam follower in one linear direction with respect to the axis of rotation during loading of the spring means.

Claim 18

The power tool of claim 13 wherein the helical cam and follower guide members are tubular members in coaxial telescoped relation.

Claim 19

The power tool of claim 16 wherein the spring means is a helical torsion spring received within the tubular helical cam and follower guide members and having opposite ends coupled to the drive means and output means with freedom of movement within the guide members for unrestricted radial contraction and axial extension responsive to loading.

Claim 20

The power tool of claim 13 further including control means for controlling application of motive power to the output means of the tool, and actuating means for actuating the control means for terminating the application of motive power to the output means.

Claim 21

The power tool of claim 18 wherein the actuating means is located in and adjustable along the path of linear movement of the cam follower.

Claim 22

In a power tool of a type having power operated rotary drive means, rotary output means for setting fasteners, an elongated housing, and a transmission received within the housing and including spring means coupling the drive means and output means, a torque indicating mechanism comprising a torque sensing device supported for linear movement longitudinally of the housing, the linear movement of the torque sensing device being proportional to deflection of the spring means upon relative rotation of the drive means and output means during a fastener setting operation, and an indicator operable responsive to linear movement of the torque sensing device for indicating torque applied by the spring means.

Claim 23

In a power tool of a type having power operated rotary drive means, rotary output means for setting fasteners, an elongated housing, and a transmission received within the housing and including spring means coupling the drive means and output means, a torque indicating mechanism comprising a torque sensing device supported for linear movement longitudinally of the housing, the linear movement of the torque sensing device being proportional to deflection of the spring means upon relative rotation of the drive means and output means during a fastener setting operation, and an indicator operable responsive to linear movement of the torque sensing device for indicating torque applied by the spring means.

Claim 24

The torque indicating mechanism of claim 20 wherein the drive means and the output means are substantially aligned for rotation about a common axis and respectively include tubular portions in coaxial telescoped relation, and wherein the torque sensing device includes a slide drivingly connected to one of the tubular portions and supported on the other thereof for linear movement within the housing upon relative rotation of the drive means and output means.

Claim 25

The torque indicating mechanism of claim 21 wherein the indicator is received in a slot formed longitudinally of the housing in the path of linear movement of the slide.

Claim 26

In a power tool of a type having power operated rotary drive means, rotary output means for setting fasteners, an elongated housing, and a transmission received within the housing and including spring means coupling the drive means and output means, a torque indicating mechanism comprising a torque sensing device received for movement within the housing in operative alignment with an opening formed in the housing, and mounting means mounting the torque sensing device for movement in proportion to loading of the spring means upon relative rotation of the drive means and output means for providing an indicAtion of the torque applied during a fastener setting operation.

Claim 27

In a power tool of a type having power operated rotary drive means, rotary output means for setting fasteners, an elongated housing, and a transmission received within the housing and including spring means coupling the drive means and output means, a torque indicating mechanism comprising a torque sensing device received for movement within the housing in operative alignment with an opening formed in the housing, and mounting means mounting the torque sensing device for movement in proportion to loading of the spring means upon relative rotation of the drive means and output means for providing an indicAtion of the torque applied during a fastener setting operation.

Claim 28

The torque indicating device of claim 23 wherein the housing opening is provided by a slot extending longitudinally of the housing, wherein an indicator is received in the slot, and wherein the torque sensing device is supported by the mounting means for movement longitudinally of the housing, the torque sensing device being movable a linear distance proportional to loading of the spring means.