Apparatus and method for detecting dangerous conditions in power equipment

• US 20020190581A1
• Filed: 06/13/2002
• Published: 12/19/2002
• Est. Priority Date: 06/13/2001
• Status: Active Grant

• Current Assignee: Sawstop Holding LLC
• Original Assignee: SD3, LLC
• Inventors: Huebner, Randall J., Fanning, David A., Gass, Stephen F., Fulmer, J. David
• Granted Patent: US 7,231,856 B2
• Time in Patent Office: Days
• US Class Current: 307/326
• CPC Class Codes: B23D 47/12 of drives for circular saw blades
• CPC Class Codes: B23D 59/001 Measuring or control devices, e.g. for automatic control of work feed pressure on band saw blade measuring in general G01; controlling in general G05
• CPC Class Codes: B23Q 5/58 Safety devices protecting the operator B23Q11/0089
• CPC Class Codes: B27B 13/14 Braking devices specially designed for band sawing machines, e.g. acting after damage of the band saw blade
• CPC Class Codes: B27B 5/38 Devices for braking the circular saw blade or the saw spindle; Devices for damping vibrations of the circular saw blade, e.g. silencing vibration-damping of sawing machines or devices working with circular saw blades B23D47/005
• CPC Class Codes: F16C 19/00 Bearings with rolling contact, for exclusively rotary movement adjustable bearings F16C23/00, F16C25/00 ; electrically insulating bearings H02K5/173
• CPC Class Codes: F16C 2322/39 General build up of machine tools, e.g. spindles, slides, actuators in general B23Q
• CPC Class Codes: F16P 3/145 using magnetic technology
• CPC Class Codes: F16P 3/148 using capacitive technology
• CPC Class Codes: H02K 5/08 Insulating casings
• CPC Class Codes: H02K 5/161 radially supporting the rotary shaft at both ends of the rotor H02K5/165, H02K5/167, H02K5/173 take precedence
• CPC Class Codes: H02K 7/10 Structural association with clutches, brakes, gears, pulleys or mechanical starters
• CPC Class Codes: H02K 7/108 with friction clutches
• CPC Class Codes: H02K 7/116 with gears
• CPC Class Codes: Y10S 83/01 Safety devices
• CPC Class Codes: Y10T 83/081 With randomly actuated stopping means
• CPC Class Codes: Y10T 83/089 Responsive to tool characteristic
• CPC Class Codes: Y10T 83/162 With control means responsive to replaceable or selectable information program
• CPC Class Codes: Y10T 83/175 With condition sensor
• CPC Class Codes: Y10T 83/7726 By movement of the tool
• CPC Class Codes: Y10T 83/7788 : Tool carrier oscillated or rotated

Abstract

A machine such as a saw, jointer, planer, etc. is disclosed. The machine has cutting tool, a direct drive mechanism configured to move the cutting tool, a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, and a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system. An electrical signal is imparted on the cutting tool, and the signal is used to determine the occurrence of the unsafe condition. The direct drive mechanism is electrically isolated so that the electric signal may be imparted on the cutting tool. The electric isolation may be achieved through configurations such as insulated bearings, a substantially non-conductive housing, and a substantially non-conductive coupling joining two shaft portions.

Claims

1. A machine comprising:

an operative structure configured to perform a task;

a cutting tool forming part of the operative structure, where the cutting tool is adapted to move in at least one motion;

at least one motor configured to move the cutting tool;

a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, where the detection system is adapted to impart an electrical signal on the cutting tool;

a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system; and

a direct drive system interconnecting the at least one motor and the cutting tool, where the direct drive system includes at least two shaft portions coupled by a substantially non-conductive coupling.

2. The machine of claim 1, where the non-conductive coupling is a gear, and where at least a portion of the gear is made of a substantially non-conductive material.

3. The machine of claim 2, where the portion of the gear made of a substantially non-conductive material is sandwiched between metal portions.

4. The machine of claim 2, where the gear includes metal teeth and a substantially non-conductive portion isolating the metal teeth.

5. The machine of claim 2, where the gear is made at least substantially from a substantially non-conductive material.

6. The machine of claim 1, where the non-conductive coupling includes a gear, a substantially non-conductive spacer that mates with the gear, and a drive hub mounted to the spacer.

7. The machine of claim 6, where the gear and drive hubs are mounted on shaft portions, where the shaft portions are supported by bearings, and where the bearings are supported in insulating bushings.

8. The machine of claim 6, where the gear and drive hubs are mounted on shaft portions, where the shaft portions are supported by bearings, and where insulating bushings are positioned between the shaft portions and the bearings.

9. The machine of claim 1, where the non-conductive coupling includes a eccentric portion, a substantially non-conductive sleeve configured to fit over and insulate the eccentric portion, and a gear configured with an opening to receive the eccentric portion and sleeve.

10. The machine of claim 1, where the substantially non-conductive coupling is a planetary gear assembly.

11. The machine of claim 10, where the planetary gear assembly includes a substantially non-conductive housing.

12. The machine of claim 10, where the planetary gear assembly includes planetary gears made from substantially non-conductive material.

13. The machine of claim 1, where the motor is a switched reluctance motor.

14. The machine of claim 1, where the operative structure comprises a direct-drive saw.

16. The machine of claim 15, where the direct drive mechanism is in a substantially non-conductive container, and the container is mounted in the operative structure.

17. The machine of claim 15, where the direct drive mechanism includes a switched reluctance motor and an electrically isolated drive shaft.

18. The machine of claim 15, where the direct drive mechanism includes a electrically isolated drive shaft.

19. The machine of claim 15, where the operative structure comprises a direct-drive saw.

15. A machine comprising:

an operative structure configured to perform a task;

a cutting tool forming part of the operative structure, where the cutting tool is adapted to move in at least one motion;

a direct drive mechanism configured to move the cutting tool;

a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, where the detection system is adapted to impart an electrical signal on the cutting tool; and

a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system;

where the direct drive mechanism is electrically isolated so that the electric signal may be imparted on the cutting tool.

20. A machine comprising:

an operative structure configured to perform a task;

a cutting tool forming part of the operative structure, where the cutting tool is adapted to move in at least one motion;

at least one motor configured to move the cutting tool;

a detection system adapted to detect the occurrence of an unsafe condition between a person and the cutting tool, where the detection system is adapted to impart an electrical signal on the cutting tool;

a reaction system adapted to mitigate the unsafe condition upon the detection of the unsafe condition by the detection system; and

means for electrically isolating the cutting tool so that the electric signal may be imparted on the cutting tool.