ELECTRIC POWER TOOL

• US 3,652,879 A
• Filed: 07/22/1970
• Issued: 03/28/1972
• Est. Priority Date: 07/22/1970
• Status: Expired due to Term

• Current Assignee: Larry E. Plunkett, Spencer C. Rees
• Original Assignee: Larry E. Plunkett, Spencer C. Rees
• Inventors: Plunkett, Larry E., Rees, Spencer C.
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Skudy, R.
• Application Number:
  US05/057,176
• Time in Patent Office: 615 Days
• Field of Search: 310/50,47,154,239,242,254 77/7
• US Class Current: 310/50
• CPC Class Codes: B25F 5/008 Cooling means
• CPC Class Codes: H02K 7/145 Hand-held machine tool
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft
• CPC Class Codes: Y10T 408/65 Means to drive tool

Abstract

An electric power tool having a housing, a fan and a motor including brushes, a commutator, an armature, and a stator. The brushes are mounted on a brush board which fits closely adjacent the commutator. The stator comprises a shell and circumferentially spaced permanent magnet segments secured to the shell, air passages being formed by the spaces between the segments. Openings are provided in the housing to permit air to be drawn in by the fan, the air being channeled by the housing and the brush board over the commutator and through the passages in the stator, thus effectively cooling the commutator and the armature of the motor.

Claims

1. An electric power tool comprising a housing having air intake and outlet openings and being split to form a cover half and a support half, and a motor having a fan for moving air through said housing, an armature, a brush assembly, and a stator having air passages formed on its inner periphery adjacent said armature, said halves having integral sockets formed therein for holding said brush assembly in position in said housing, said housing having integral wall portions extending generally radially inward adjacEnt said stator, said wall portions holding said stator in position in said housing and cooperating with said stator to block air flow around the outer periphery of said stator and thus channel substantially all the air through said air passages for cooling said armature.

2. A tool as in claim 1, wherein said stator includes a plurality of spaced magnet segments, said spaces between said magnet segments forming said air passages.

3. A tool as in claim 1, wherein said stator includes a shell and ceramic magnet segments, said ceramic magnet segments being spaced apart in said shell, said ceramic magnet segments forming said air passages therebetween.

4. A tool as in claim 1, and further comprising a commutator secured to said armature, said brush assembly including a brush board mounted in and extending from said housing to closely adjacent said commutator for directing air flow around said commutator.

5. A tool as in claim 1, wherein said fan is mounted in front of said stator, said intake opening being located at the rear of said housing, said outlet opening being located at the side of said housing, said intake and outlet openings being at opposite ends of said stator.

6. An electric power tool comprising a housing having air intake and outlet openings, a motor, a fan connected to said motor for moving air through said housing, said motor including an armature, a commutator secured to said armature, and a brush assembly including brushes contacting said commutator and a brush board having a center opening therein, said commutator rotating in said center opening of said board, said housing having socket portions extending generally inward for holding said brush board in position in said housing, said brush board cooperating with said housing to direct the air through said center opening for cooling said commutator.

7. A tool as in claim 6, wherein said brush board has a notch in a margin thereof, and said tool further comprises at least one electric wire connected to one of said brushes, said wire being positioned in and tightly secured in said notch whereby should said wire break said wire will be retained within said housing so as not to contact an operator of said tool.

8. A tool as in claim 6, wherein said brush board is made of an insulating material, and further includes brush holders for holding said brushes, said brush holders being secured to said board, said brush assembly being entirely contained within said housing and being replaceable only by disassembly of said housing.