Speed controller for flywheel operated hand tool

• US 6,796,475 B2
• Filed: 12/20/2001
• Issued: 09/28/2004
• Est. Priority Date: 12/22/2000
• Status: Expired due to Term

• Current Assignee: Kyocera Senco Industrial Tools, Inc. (Kyocera Corporation)
• Original Assignee: Senco Products Incorporated (Kyocera Corporation)
• Inventors: Adams, Shane
• Primary Examiner(s): Gerrity, Stephen F.
• Assistant Examiner(s): Nash, Brian D
• Application Number:
  US10/027,768
• Publication Number:
  US 20020108474A1
• Time in Patent Office: 1,013 Days
• Field of Search: 227/2, 227/129, 227/133, 227/131
• US Class Current: 227/2
• CPC Class Codes: B25C 1/06 operated by electric power
• CPC Class Codes: H02P 27/047 V/F converter, wherein the voltage is controlled proportionally with the frequency
• CPC Class Codes: H02P 3/08 for stopping or slowing a dc motor

Abstract

A speed controller operates a DC-powered fastener drive assembly to efficiently drive fasteners from a DC power supply, thereby achieving a fully portable hand tool. In particular, the speed controller accelerates a flywheel with a DC motor to a target speed appropriate for the type of fastener and user selection. Thereafter, the speed controller causes the kinetic energy from the flywheel to be imparted to a linearly moving fastener driver. The speed controller is responsive to the rotational speed of the flywheel to ensure a consistent depth of drive and to actuate a clutch for an appropriate amount of time to couple the flywheel to the fastener driver. Thereby, consistent drives are achievement across a range of operating conditions (e.g., battery state of charge, type of fastener, mechanical tolerances and wear, motor performance, etc.).

Claims

1. A controller for a hand tool having an inertial member accelerated by a motive device and selectively coupled by a clutch to driver to impart kinetic energy to a fastener for driving the fastener into a workpiece, the speed controller comprising:

a sensor operable to sense a parameter of the inertial member indicative of kinetic energy therein; and

a circuit arrangement operably configured to command the clutch to impart the kinetic energy of the inertial member in response to both a user input and to the sensed parameter reaching a target value;

wherein the circuit arrangement is further operably configured to monitor the parameter of the flywheel after commanding actuation of the clutch assembly, and to command deactuation of the clutch assembly in response to the monitored parameter reaching a threshold.

2. The controller of claim 1, wherein the inertial member of the hand tool comprises a flywheel, the sensor configured to sense the parameter of rotary speed.

3. The controller of claim 2, wherein the sensor comprises:

a plurality of magnetic poles placed on the flywheel; and

an inductive pickup positioned proximate to the flywheel to sequentially sense the plurality of magnetic poles.

4. The controller of claim 3, wherein the plurality of magnetic poles comprises a first ring of magnetic poles having a same selected polarity and a second ring of magnetic poles concentric with the first ring and having an opposite polarity, the inductive pickup comprising a first inductive pickup registered to sense the first ring and a second inductive pickup registered to sense the second ring.

5. The controller of claim 4, wherein the sensor further comprises:

a comparator having as inputs the first and second inductive pickups and providing as an output a periodic signal representative of the rotary speed of the flywheel; and

a circuit configured to convert the periodic signal into an amplitude representative of the rotary speed.

6. The controller of claim 1, wherein the circuit is further configured to produce an indexing signal after the command to clutch.

7. The controller of claim 1, wherein the circuit arrangement is further operably configured to time the commanded activation of the clutch assembly, and to determine a clutch failed open condition in response to the timed activation exceeding a clutch timeout value.

8. The controller of claim 1, wherein the circuit arrangement is further operably configured, in response to a user input, to initiate acceleration of the flywheel toward the target.

9. The controller of claim 8, wherein the user input is a continuous mode enabling event and the circuit arrangement is further operably configured to command activation of the clutch assembly in response to receiving a command to drive a fastener by maintaining the kinetic energy of the flywheel until the clutch assembly is activated.

10. The controller of claim 9, wherein the circuit arrangement is further operably configured to time the maintenance of kinetic energy of the flywheel, and to cease maintaining the kinetic energy of the flywheel in response to exceeding a no operation time-out value.

11. The controller of claim 8, wherein the circuit arrangement is further operably configured to time acceleration of the flywheel toward the target, and to determine a failed condition in response to the flywheel failing to accelerate to the target within a motor start time-out value.

12. The controller of claim 8, wherein the circuit arrangement is further operably configured to initiate acceleration of the flywheel with a soft start command followed by a full acceleration command.

13. The controller of claim 8, wherein the user input is a continuous mode enabling event and the controller is further operably configured to command activation of the clutch assembly in response to receiving a command to drive a fastener by maintaining the kinetic energy of the flywheel until the clutch assembly is activated.

14. The controller of claim 8, wherein the controller is further operably configured to time acceleration of the flywheel toward the target, and to determine a failed condition in response to the flywheel failing to accelerate to the target within a motor start time-out value.

15. The controller of claim 8, wherein the controller is further operably configured to initiate acceleration of the flywheel with a soft start command followed by a full acceleration command.

16. The controller of claim 9, wherein the controller is further operably configured to time the maintenance of kinetic energy of the flywheel, and to cease maintaining the kinetic energy of the flywheel in response to exceeding a no operation time-out value.

17. The controller of claim 1, wherein the circuit arrangement is further operably configured to access a mode setting selected from a group consisting of a continuous mode and an intermittent mode, and to initiate acceleration of the flywheel toward the target and maintaining the kinetic energy of the flywheel at the target when the accessed mode setting is continuous mode, and to initiate acceleration of the flywheel toward the target when the accessed mode setting is intermittent mode in response to a user dispense command.

18. The controller of claim 1, wherein the user input comprises a user dispense command, the circuit arrangement is further operably configured to sense and time a held safety signal, to sense a trigger signal, and to determine a user dispense command when the held safety signal precedes and is simultaneous with the trigger signal so long as the held safety signal precedes the trigger signal by no more than a valid trigger time-out value.

19. The controller of claim 18, wherein the circuit arrangement is further operably configured to sense the trigger signal by de-bouncing the trigger signal.

20. The controller of claim 18, wherein the controller is further operably configured to sense the trigger signal by de-bouncing the trigger signal.

21. The controller of claim 1, wherein the circuit arrangement is further operably configured to electrically signal indexing a next fastener after commanding activation of the clutch assembly.

22. The controller of claim 1, wherein the controller is further operably configured, in response to a user input, to initiate acceleration of the flywheel toward the target.

23. The controller of claim 1, wherein the controller is further operably configured to access a mode setting selected from a group consisting of a continuous mode and an intermittent mode, and to initiate acceleration of the flywheel toward the target and maintaining the kinetic energy of the flywheel at the target when the accessed mode setting is continuous mode, and to initiate acceleration of the flywheel toward the target when the accessed mode setting is intermittent mode in response to a user dispense command.

24. The controller of claim 1 wherein the user input comprises a user dispense command, the controller is further operably configured to sense and time a held safety signal, to sense a trigger signal, and to determine a user dispense command when the held safety signal precedes and is simultaneous with the trigger signal so long as the held safety signal precedes the trigger signal by no more than a valid trigger time-out value.

25. The controller of claim 1, wherein the controller is further operably configured to electrically signal indexing a next fastener after commanding activation of the clutch assembly.

26. A portable hand tool for dispensing fasteners into a workpiece, comprising:

a fastener magazine configured to contain fasteners;

a fastener drive assembly comprising;

an inertial member;

an electrical motive device in mechanical communication with the inertial member to cause acceleration thereof;

a driver linearly movable to drive a fastener from the fastener magazine; and

a clutch selectively coupled to the inertial member and the driver to impart kinetic energy from the inertial member to the fastener;

a sensor operable to sense a parameter representing kinetic energy of the inertial member; and

a controller operatively configured to respond to both a user input and to the sensed parameter reaching a target value to command the fastener drive assembly;

wherein the controller is further operably configured to monitor the parameter of the flywheel after commanding actuation of the clutch assembly, and to command deactuation of the clutch assembly in response to the monitored parameter reaching a threshold.

27. The portable hand tool of claim 26, further comprising a battery, wherein the controller and the fastener drive assembly are powered by the battery.

28. The portable hand tool of claim 26, wherein the controller is further operably configured to time the commanded activation of the clutch assembly, and to determine a clutch failed open condition in response to the timed activation exceeding a clutch timeout value.

29. A portable hand tool for dispensing fasteners into a workpiece, comprising:

a fastener magazine configured to contain fasteners;

a fastener drive assembly comprising;

an inertial member;

an electrical motive device in mechanical communication with the inertial member to cause acceleration thereof;

a driver linearly movable to drive a fastener from the fastener magazine; and

a clutch selectively coupled to the inertial member and the driver to impart kinetic energy from the inertial member to the fastener;

a sensor operable to sense a parameter representing kinetic energy of the inertial member; and

a controller means responsive to both a user input and to the sensed parameter reaching a target value for commanding the fastener drive assembly.