EP0677361A1 - Scie à chaîne avec frein compact - Google Patents

Scie à chaîne avec frein compact Download PDF

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Publication number
EP0677361A1
EP0677361A1 EP94116795A EP94116795A EP0677361A1 EP 0677361 A1 EP0677361 A1 EP 0677361A1 EP 94116795 A EP94116795 A EP 94116795A EP 94116795 A EP94116795 A EP 94116795A EP 0677361 A1 EP0677361 A1 EP 0677361A1
Authority
EP
European Patent Office
Prior art keywords
chain saw
cup gear
brake
chain
drive shaft
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94116795A
Other languages
German (de)
English (en)
Inventor
Mark Earnest Baer
Robert Lent Creveling, Jr.
David Eugene Ebersole
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mcculloch Corp
Original Assignee
Mcculloch Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mcculloch Corp filed Critical Mcculloch Corp
Publication of EP0677361A1 publication Critical patent/EP0677361A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
    • B27B17/00—Chain saws; Equipment therefor
    • B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw
    • B27B17/083—Devices for arresting movement of the saw chain
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
    • B27B17/00—Chain saws; Equipment therefor
    • B27B17/08—Drives or gearings; Devices for swivelling or tilting the chain saw

Definitions

  • the present invention relates to chain saws, and more particularly, to a chain braking arrangement for chain saws.
  • Kickback typically occurs when the tip of the saw contacts the wood being cut, or another solid object, resulting in a violent upward motion which can endanger the operator.
  • the risk of injury can be minimized by stopping the saw chain whenever a kickback occurs or whenever the operator is at risk of coming into contact with the saw chain.
  • a band brake for a chain saw comprising a flexible metallic band which is wrapped around a brake drum.
  • One end of the band is fixed to the chain saw casing or chassis.
  • the other end is attached to a mechanical linkage via a biasing means, typically a spring.
  • a biasing means typically a spring.
  • the band In a brake-off condition, the band is loosely wound around the brake drum, and is not in contact therewith.
  • the band is tightened around the brake drum by the biasing means such that the friction between the band and the brake drum stops the saw chain substantially instantaneously.
  • Wieland et al. U.S. Pat. No. 4,662,072 discloses a band brake for a chain saw wherein a brake drum is located on a motor drive shaft. This patent alternatively discloses that the brake drum can be located elsewhere in the drive train of the saw.
  • Other prior art designs use the outer casing of a centrifugal clutch as the brake drum. See, e.g., Hirschkoff, U.S. Pat. No. 4,026,392.
  • Cup gears and ring gears have numerous advantages over conventional gears, such as the conservation of space in the chain saw housing. Cup gears also protect the gear and pinion mechanisms from contaminants, such as sawdust and dirt. As discussed in the Irgens '162 patent, cup gears and ring gears can also reduce the torque on the drive shaft by minimizing the moment arm acting on the drive shaft. In addition, cup gears and ring gears have relatively large rotational moments of inertia, when compared to conventional gears with external teeth. As discussed in the Haupt et al. '179 patent, this results in enhanced performance of the chain saw, especially at low speeds.
  • a cup gear is utilized as a braking structure in a chain saw. More specifically, a pinion driven by a drive shaft of a motive power means drives a cup gear which in turn drives a chain sprocket. The cup gear carries a braking surface which is acted upon by a braking means to selectively bring the saw chain to a halt.
  • the braking surface can be an outer circumferential surface of the cup gear.
  • the braking surface can be an outer circumferential surface of a brake drum secured to the outside of the cup gear.
  • An electric motor can be used as the motive power means in a chain saw embodying the present invention, and a brake band can be used as the braking means.
  • the pinion can be directly driven by the drive shaft for rotation therewith at all times during operation of the chain saw.
  • the chain sprocket can be directly driven by the cup gear for rotation therewith at all times during the operation of the chain saw.
  • a mechanical linkage may be used to activate the braking means.
  • a band brake is used in an electric chain saw having a cup gear as a reduction gear.
  • the band brake comprises a flexible metallic band having two ends and a brake drum fixedly attached to the outer surface of the cup gear.
  • a mechanical linkage is used to actuate the band brake.
  • the mechanical linkage comprises a pivotally mounted safety brake lever which carries a pin engaging a cam follower plate attached to the brake band.
  • a helical compression spring biases the brake band in tension tightly around the brake drum.
  • the present invention allows for significant weight reduction in the chain saw braking mechanism.
  • the invention also provides for a compact braking configuration, thereby reducing the width of the chain saw and the effective moment arm acting on the drive shaft during braking.
  • a chain saw constructed in accordance with one embodiment of the present invention wherein the outer circumference of the cup gear is used as a braking surface will have fewer parts, thereby reducing manufacturing costs.
  • a chain saw 10 includes a saw chain 12, a guide bar 13, a rear handle 14, a front handle 16, a motor housing 18, a gear housing 19, and a safety brake lever 20.
  • Figs. 2 and 4 show a braking and drive mechanism 21 of the present invention in a first or brake-off position or configuration.
  • a pinion 22 is fixedly attached to a motor drive shaft 24 which is driven by a motor 25.
  • a plurality of pinion teeth 26 disposed on the pinion 22 engage a plurality of cup gear teeth 28 disposed on an inner surface 30 of a cylindrical wall 32 of a cup gear 34.
  • a chain sprocket 36 is fixedly attached to the cup gear 34.
  • the chain sprocket 36 drives the saw chain 12 as it moves along the guide bar 13. It should be noted that the bottom side of the saw chain 12 moves toward the chain sprocket 36.
  • the chain sprocket 36, cup gear 34, and pinion 22 all rotate in a clockwise direction as indicated in Fig. 2 by an arrow 37.
  • the braking and drive mechanism 21 comprises a brake band 38 disposed around a brake drum 40.
  • the brake drum 40 is rigidly attached to the cup gear 34 by a plurality of stamped bosses 42 which extend into a plurality of corresponding bores 44 in the cup gear 34.
  • Each boss 42 includes an enlarged head 46 which, together with an axial face 48 of the brake drum 40, capture the cup gear 34 therebetween.
  • the brake drum 40 could be secured to the cup gear 34 by another means of attachment, such as bolts, screws, or rivets.
  • a motor housing partition 50 separates the motor 25 from the braking and drive mechanism 21.
  • an angle bracket 51 having a vertical portion 52 and a horizontal portion 54, and a guide bar support 56 protrude from the motor housing partition 50 and form a channel 58 therebetween.
  • a fixed end 60 of the brake band 38 is bent at approximately a right angle so that it fits in the channel 58 and bears against the vertical portion 52 of the angle bracket 51. Other means of securing the fixed end 60 of the brake band 38 may alternatively be used.
  • a moveable end 62 of the brake band 38 is secured by any suitable means to a cam follower plate 63.
  • One suitable means of attachment comprises the following arrangement.
  • the moveable end 62 of the brake band 38 may be twisted 90 degrees so that it aligns with an outward facing surface 64 of the cam follower plate 63.
  • the moveable end 62 of the brake band 38 may be attached to the cam follower plate 63 by a post (not shown) extending from the cam follower plate 63 which engages a hole (not shown) in the moveable end 62 of the brake band 38.
  • the cam follower plate 63 is pivotally mounted to the motor housing partition 50 by a cam follower plate mounting pin 65.
  • a fixed end 66 of a helical compression spring 68 is fixed within a retaining hole 70 in the motor housing partition 50.
  • a moveable end 72 of the helical compression spring 68 bears against a rearward side 73 of the cam follower plate 63, and may also be attached thereto by any suitable means.
  • a roller pin 74 carried by the safety brake lever 20 engages a forward side 75 of the cam follower plate 63.
  • the safety brake lever 20 is pivotally mounted to the motor housing partition 50 by a safety brake lever mounting pin 76.
  • the safety brake lever 20 In the brake-off configuration (as depicted in Fig. 2), the safety brake lever 20 is disposed in a substantially upward or vertical position and the roller pin 74 engages an indentation 78 and a lobe 80 on the cam follower plate 63 such that the cam follower plate 63 is prevented from rotation about the cam follower plate mounting pin 65.
  • the helical compression spring 68 is in a compressed state and the brake band 38 is loosely wrapped around the brake drum 40 such that the brake band 38 is not in contact therewith.
  • an arm 82 on the safety brake lever 20 engages a first arm 84 of a brake switch actuator 86 pivotally mounted on the motor housing partition 50 at a brake switch actuator mounting pin 88.
  • a second arm 90 of the brake switch actuator 86 engages a spring-loaded plunger 92 of a microswitch 94.
  • the microswitch 94 is configured such that electrical power is supplied to the motor 25 (Fig. 3) when the plunger 92 is depressed.
  • the plunger 92 is pushed outward from the microswitch 94 by a spring (not shown) such that the plunger 92 is extended and the microswitch 94 is open in the absence of pressure on the plunger 92.
  • FIG. 3 A second or brake-on position or configuration is depicted in Fig. 3.
  • the roller pin 74 moves upwardly, releasing the cam follower plate 63 for clockwise rotation under the influence of the force applied by the helical compression spring 68.
  • the brake band 38 thus is pulled tightly around the brake drum 40 and the friction between the brake band 38 and a cylindrical flange 96 (Fig. 4) of the brake drum 40 brings the saw chain 12 (not shown in Fig. 3) quickly to a halt.
  • the brake drum 40 surrounds the cup gear 34 and the cylindrical flange 96 of the brake drum 40 provides a braking surface 97 with which the brake band 38 comes into frictional contact during braking.
  • the cylindrical flange 96 of the brake drum 40 may be radially spaced outwardly from an outer cylindrical surface 98 of the cup gear 34. This separation facilitates air flow around the cylindrical flange 96 of the brake drum 40 for better cooling. Also, it helps minimize heat transfer from the brake drum 40 to the cup gear 34.
  • the cup gear 34 can be made of a less durable, more inexpensive material, such as plastic.
  • Fig. 5 shows an alternative embodiment of the present invention wherein elements common to Figs. 2-4 are assigned like reference numerals.
  • an outer surface 198 of a cup gear 134 is utilized as a braking surface.
  • the cup gear 134 must be manufactured from a durable material, such as steel.
  • this design results in more weight in the cup gear 134, the absence of a separate brake drum (40 in Fig. 4) simplifies the manufacture of the chain saw. Also, the additional inertia of a heavier cup gear 134 improves performance of the saw at low speeds.
EP94116795A 1994-03-22 1994-10-25 Scie à chaîne avec frein compact Withdrawn EP0677361A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US215610 1980-12-12
US21561094A 1994-03-22 1994-03-22

Publications (1)

Publication Number Publication Date
EP0677361A1 true EP0677361A1 (fr) 1995-10-18

Family

ID=22803679

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94116795A Withdrawn EP0677361A1 (fr) 1994-03-22 1994-10-25 Scie à chaîne avec frein compact

Country Status (4)

Country Link
EP (1) EP0677361A1 (fr)
AU (1) AU1168895A (fr)
CA (1) CA2118472A1 (fr)
SE (1) SE9501047L (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010008328A1 (fr) * 2008-07-14 2010-01-21 Husqvarna Ab Protège-main pour scie à chaîne

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106625890B (zh) * 2016-11-30 2022-06-24 江门沙龙实业有限公司 一种装夹牢固的切角机

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3857179A (en) * 1974-04-22 1974-12-31 Desa Industries Chain saw
US3992779A (en) * 1973-12-21 1976-11-23 Textron, Inc. Chain brake for chain saw
FR2523245A1 (fr) * 1982-03-13 1983-09-16 Stihl Andreas Dispositif de freinage, notamment pour tronconneuse
US4406645A (en) * 1980-10-30 1983-09-27 Black & Decker Inc. Sprocket-brake drum construction for chain saw
DE3510471A1 (de) * 1984-03-21 1985-09-26 Makita Electric Works Ltd., Anjo, Aichi Tragbare kettensaege
US4662072A (en) * 1982-12-03 1987-05-05 Andreas Stihl Chain saw having a braking arrangement

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3992779A (en) * 1973-12-21 1976-11-23 Textron, Inc. Chain brake for chain saw
US3857179A (en) * 1974-04-22 1974-12-31 Desa Industries Chain saw
US4406645A (en) * 1980-10-30 1983-09-27 Black & Decker Inc. Sprocket-brake drum construction for chain saw
FR2523245A1 (fr) * 1982-03-13 1983-09-16 Stihl Andreas Dispositif de freinage, notamment pour tronconneuse
US4662072A (en) * 1982-12-03 1987-05-05 Andreas Stihl Chain saw having a braking arrangement
DE3510471A1 (de) * 1984-03-21 1985-09-26 Makita Electric Works Ltd., Anjo, Aichi Tragbare kettensaege

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010008328A1 (fr) * 2008-07-14 2010-01-21 Husqvarna Ab Protège-main pour scie à chaîne
CN102089128A (zh) * 2008-07-14 2011-06-08 胡斯华纳有限公司 链锯的手防护装置
US20140310965A1 (en) * 2008-07-14 2014-10-23 Husqvarna Ab Hand guard for chainsaw
US8973276B2 (en) 2008-07-14 2015-03-10 Husqvarna Ab Handguard for chainsaw

Also Published As

Publication number Publication date
AU1168895A (en) 1995-09-28
SE9501047D0 (sv) 1995-03-22
SE9501047L (sv) 1995-09-23
CA2118472A1 (fr) 1995-09-23

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