Electric manual machine tool driven by an electric motor

• US 7,196,440 B2
• Filed: 04/28/2004
• Issued: 03/27/2007
• Est. Priority Date: 04/29/2003
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lamprecht, Justus
• Primary Examiner(s): NGUYEN, TRAN N
• Application Number:
  US10/520,432
• Publication Number:
  US 20050247468A1
• Time in Patent Office: 1,063 Days
• Field of Search: 310/233, 310235-237, 310/43, 310/58, 310/60.R, 310/60.A
• US Class Current: 310/60.00A
• CPC Class Codes: H01R 39/04 Commutators wherein the segments are formed by extensions of dynamo-electric machine winding H02K
• CPC Class Codes: H01R 39/54 by use of impedance between brushes or segments
• CPC Class Codes: H02K 13/006 Structural associations of commutators
• CPC Class Codes: H02K 13/105 Spark suppressors associated with the commutator
• 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

Abstract

A hand power tool that is driven via an electric motor (20), the electric motor (20) having a commutator (28) which is formed of disklike annular segments or laminations (32), is made more secure against contact spark development by providing that at least one of the laminations (32) has at least one central recess (42, 44, 46).

Claims

1. A hand power tool, comprising an electric motor having a commutator, said commutator being composed of a plurality of laminations having a central recess and forming a perforated section in said commutator, said recess being elongated in an axial direction and configured as a continuous opening, said laminations further having peripheral recesses which are arranged next to said central recess and provide a trapezoidal contour at ends of a periphery, so that said laminations have an anvil-shaped contour, said central elongated recess extending transversely through said laminations and forming an annular conduit, wherein said central recess is configured so that a flow of cooling air is passed through said central recesses in said laminations.

2. A hand power tool as defined in claim 1 wherein said central recess is configured as a punched recess with a closed, thin remaining wall.

3. A hand power tool as defined in claim 1, wherein said recess passes in aligned fashion through two diametrically opposed flat sides of said laminations.

4. A hand power tool as defined in claim 1 wherein said central recess is oval.

5. A hand power tool as defined in claim 1 wherein regions of each of said laminations above said central recess are configured so that at operating rpm and operating temperature they deform in such a way that a face to be electrically contacted with carbon brushes essentially forms a plane.

6. A hand power tool as defined in claim 1, wherein outer ends of said laminations are configured so that they act as a fan and put a flow of cooling air through said laminations into motion.

7. A hand power tool as defined in claim 1;

and further comprising an annular armature which reaches through a recess selected from the group consisting of said central recess and said peripheral recess.

8. A hand power tool as defined in claim 7, wherein said annular armature is prestressed.

9. A hand power tool as defined in claim 1;

and further comprising a tubular-stub-like everted feature each provided on one side of each of said laminations in a region of said central recess and protruding into said central recess on another side on each adjacent one of said laminations; and

an insulating material provided between two adjacent ones of said laminations.