# US 9,518,616 B2 · Hand-held power tool with a clutch and method for producing a groove in the circumferential wall of a clutch drum of a hand-held power tool

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- Number: US 9,518,616 B2
- Document ID: US9518616B2
- Status: Granted
- Kind: B2
- Application number: 14/669,218
- Filed: 2015-03-26
- Published: 2015-10-08
- Granted: 2016-12-13
- Earliest claimed: 2014-04-05
- Assignees: Andreas Stihl AG & Co. KG
- Applicants: Andreas Stihl AG & Co. KG
- Inventors: Günter Wolf; Marcel Förster
- Web page: https://patentgrep.com/patent/US9518616B2

## CPC

- F16D 13/62: Clutch-bands; Clutch shoes; Clutch-drums (brake-bands, brake-shoes, brake-drums F16D65/00)
- B21D 28/00: Shaping by press-cutting; Perforating
- B21J 5/00: Methods for forging, hammering, or pressing (for working sheet-metal or metal tubes, rods, or profiles B21D; for working wire B21F); Special equipment or accessories therefor
- B27B 17/10: Transmission clutches specially designed for chain saws
- F16D 43/14: with centrifugal masses actuating the clutching members directly in a direction which has at least a radial component; with centrifugal masses themselves being the clutching members
- F16D 43/18: with friction clutching members
- F16D 67/02: Clutch-brake combinations
- F16D 13/644: {Hub construction}
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- B21D: WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (working or processing of wire B21F)
- B21J: FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES (rolling of metal B21B; making particular products by forging or pressing B21K; cladding or plating B23K; finishing surfaces by hammering B23P9/04; compacting surfaces by blasting with particulate material B24C1/10; general features of presses, presses for consolidating scrap B30B; furnaces in general F27)
- B27B: SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR (saws specially adapted for pruning or debranching A01G3/08; sawing apparatus specially adapted for felling trees A01G23/091; features not restricted to a particular type of wood saw B23D, e.g. attaching saw blades B23D51/00; machine tool frames, beds, pillars or like members, in general B23Q1/01)

## Abstract

A hand-held power tool is provided with a drive motor and a clutch connected to the drive motor. The drive motor drives a tool member through the clutch. The clutch has a clutch drum with a circumferential wall provided with an end face. A follower member engages a groove in the circumferential wall of the clutch drum and a driven element is connected to the follower member to be driven by the follower member. The groove extends from the end face of the circumferential wall into the circumferential wall and has a groove bottom and two groove sides positioned opposite each other. The circumferential wall has a protrusion located at the groove bottom. The protrusion has a protrusion thickness measured at the groove bottom that amounts to at least approximately 110% of a wall thickness of the circumferential wall measured at the two groove sides.

## Claims

### Claim 1

A hand-held power tool comprising:
a drive motor;
a clutch connected to the drive motor, wherein the drive motor drives a tool member through the clutch;
the clutch comprising a clutch drum and the clutch drum comprising a circumferential wall provided with an end face, wherein the clutch is a centrifugal clutch comprising at least one flyweight, wherein the at least one flyweight in an engaged state of the clutch is resting on an inner side of the circumferential wall;
a follower member engaging a groove provided in the circumferential wall of the clutch drum, the groove extending from the end face of the circumferential wall into the circumferential wall and comprising a groove bottom and two groove sides positioned opposite each other;
a driven element that is connected to the follower member to be driven by the follower member;
wherein the circumferential wall comprises a protrusion located at the groove bottom, wherein the protrusion has a protrusion thickness measured at the groove bottom that amounts to at least approximately 110% of a wall thickness of the circumferential wall measured at the two groove sides.

### Claim 2 (depends on 1)

The power tool according to claim 1, wherein the protrusion has a protrusion width measured parallel to an axis of rotation of the clutch and the protrusion width amounts to from approximately 0.8 mm to approximately 2.0 mm.

### Claim 3 (depends on 1)

The power tool according to claim 1, wherein the protrusion has a protrusion length measured in a circumferential direction of the clutch drum and the protrusion length amounts to from approximately 50% to approximately 200% of a groove width of the groove.

### Claim 4 (depends on 1)

The power tool according to claim 1, wherein the circumferential wall has an inner side and the inner side comprises a raised portion in an area next to the groove bottom, wherein the raised portion is raised relative to an area of the inner side next to the two groove sides.

### Claim 5 (depends on 4)

The power tool according to claim 4, wherein a rise of the raised portion amounts to from approximately 0.05 mm to approximately 0.3 mm.

### Claim 6 (depends on 1)

The power tool according to claim 1, wherein the circumferential wall has an outer side and the outer side comprises a raised portion in an area next to the groove bottom, wherein the raised portion is raised relative to an area of the inner side next to the two groove sides.

### Claim 7 (depends on 6)

The power tool according to claim 6, wherein a rise of the raised portion amounts to from approximately 0.05 mm to approximately 0.3 mm.

### Claim 8 (depends on 1)

The power tool according to claim 1, wherein the circumferential wall in the area next to the groove sides has no protrusion.

### Claim 9 (depends on 1)

The power tool according to claim 1, wherein the groove sides comprise an area adjoining the end face and are positioned in the area adjoining the end face at an angle relative to each other that opens toward the end face.

### Claim 10 (depends on 9)

The power tool according to claim 9, wherein the angle is at least approximately 10°.

### Claim 11 (depends on 1)

The power tool according to claim 1, wherein the groove sides are mirror-symmetrical to each other.

### Claim 12 (depends on 1)

The power tool according to claim 1, wherein the driven element is a pump.

### Claim 13

A hand-held power tool comprising:
a drive motor;
a clutch connected to the drive motor, wherein the drive motor drives a tool member through the clutch;
the clutch comprising a clutch drum and the clutch drum comprising a circumferential wall provided with an end face;
a follower member engaging a groove provided in the circumferential wall of the clutch drum, the groove extending from the end face of the circumferential wall into the circumferential wall and comprising a groove bottom and two groove sides positioned opposite each other;
a driven element that is connected to the follower member to be driven by the follower member;
wherein the circumferential wall comprises a protrusion located at the groove bottom, wherein the protrusion has a protrusion thickness measured at the groove bottom that amounts to at least approximately 110% of a wall thickness of the circumferential wall measured at the two groove sides;
a brake device comprising a brake belt, wherein the brake belt interacts for braking with an outer side of the circumferential wall.

### Claim 14

A method for producing a groove in a circumferential wall of a clutch drum of a clutch of a hand-held power tool, the hand-held power tool comprising: a drive motor; a clutch connected to the drive motor, wherein the drive motor drives a tool member through the clutch and the clutch comprises a clutch drum and the clutch drum comprises a circumferential wall provided with an end face; a follower member engaging a groove provided in the circumferential wall of the clutch drum, wherein the groove extends from the end face of the circumferential wall into the circumferential wall and comprises a groove bottom and two groove sides positioned opposite each other; a driven element that is connected to the follower member to be driven by the follower member; wherein the circumferential wall comprises a protrusion located at the groove bottom, wherein the protrusion has a protrusion thickness measured at the groove bottom that amounts to at least approximately 110% of a wall thickness of the circumferential wall measured at the two groove sides; the method comprising:
die cutting a groove with a die-cut groove depth that amounts to approximately 75% up to approximately 95% of a nominal groove depth of the groove and with a die-cut groove width that amounts to approximately 50% up to approximately 110% of a nominal groove width of the groove; and
subsequently plastically deforming a groove bottom of the die-cut groove until the nominal groove depth is reached.

### Claim 15 (depends on 14)

The method according to claim 14, wherein the die-cut groove depth of the die-cut groove is at most 2.0 mm smaller than the nominal groove depth.