WO1994013441A2 - Mecanisme de securite pour outil a moteur - Google Patents

Mecanisme de securite pour outil a moteur Download PDF

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Publication number
WO1994013441A2
WO1994013441A2 PCT/GB1993/002584 GB9302584W WO9413441A2 WO 1994013441 A2 WO1994013441 A2 WO 1994013441A2 GB 9302584 W GB9302584 W GB 9302584W WO 9413441 A2 WO9413441 A2 WO 9413441A2
Authority
WO
WIPO (PCT)
Prior art keywords
band
passage
actuating mechanism
lever
braking
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.)
Ceased
Application number
PCT/GB1993/002584
Other languages
English (en)
Other versions
WO1994013441A3 (fr
Inventor
Harbey Kuplas
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.)
Goblin Ltd
Original Assignee
Goblin Ltd
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 Goblin Ltd filed Critical Goblin Ltd
Priority to AU57067/94A priority Critical patent/AU5706794A/en
Priority to FI952988A priority patent/FI952988A7/fi
Priority to EP94902894A priority patent/EP0675786A1/fr
Publication of WO1994013441A2 publication Critical patent/WO1994013441A2/fr
Publication of WO1994013441A3 publication Critical patent/WO1994013441A3/fr
Priority to NO952389A priority patent/NO952389L/no
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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

Definitions

  • This invention relates to an actuating mechanism for a power operated tool.
  • the actuating mechanism has been developed for use with a chain saw, but it is envisaged that it will find application in other tools, particularly ones where similar safety requirements exist.
  • Some power operated tools such as chain saws can be particularly dangerous. It is known for serious accidents to occur to operators using chain saws. For example a chain saw can rear rapidly from an object being cut to strike an operator on his head. As a consequence increasingly stringent safety standards are being applied to such tools.
  • a guard mounted forwardly of the left-hand grip on the body of the tool housing.
  • Such guard is pivotally mounted on an arm and requires locking into position before power can be applied to the motor of the saw by operation of a switch associated with the right-hand grip on the housing.
  • a brake which in the event that the tool is subject to an impulse, resulting in it rising rapidly, is applied in a certain minimum period of time.
  • the brake takes the form of a disc or drum mounted on the shaft of the motor with a braking band located around the disc. In response to the sensing of an impulse the band is caused to engage tightly around the periphery of the disc and hence stop motion of the motor.
  • the present invention is concerned with an actuating mechanism which permits the use of any number of operating members and which can make use of the existing braking mechanism in order to achieve the required braking effect.
  • an actuating mechanism for a power operated tool comprising one or more manually operable members mounted on the housing of the tool, a predetermined number of said members having to be operated in order to cause the driving means of the tool to be energised, a braking mechanism associated with the drive means and arranged so that it normally applies a braking action to the drive means, and a passage containing a movable medium, said passage at one end having means which can release the braking means in response to movement of the medium in the passage and the or each operating member being operatively coupled to the medium in said passage such that movement of each member causes a predetermined movement of said medium, the arrangement being such that movement of said predetermined number of members causes sufficient movement of the medium to release the braking means.
  • the number of operating members will be selected according to the requirements of the tool to which the actuating mechanism is fitted. In the case of a chainsaw it is envisaged that there will be three operating members, the third member being provided in proximity to the guard member.
  • the mechanism includes a switch connected in the energising circuit of the drive means, said switch being normally in an open circuit condition and being arranged to assume a close circuit condition only when said predetermined number of the manually operable members have been operated.
  • the medium may comprise a plurality of balls disposed in a tubular passage.
  • the passage may be any suitable shape, e.g. circular or square.
  • the balls may be arranged to move approximately one diameter each time an operating member is operated.
  • Another aspect of the invention provides a braking band for use in connection with a disc-like member mounted on a shaft which is to be braked, said band being formed from a strip of resilient material and being formed into a generally circular shape from which opposite ends extend tangentially at substantially the same circumferential position.
  • Figure 1 is a schematic view of a chain saw
  • Figure 2 is a side elevation illustrating an actuating mechanism in accordance with the present invention
  • Figure 2a is a view similar to Figure 2, but with some elements omitted for clarity;
  • Figure 2b is a view showing in more detail the structure of the plunger used in the actuating mechanism
  • Figure 3a is a side view of the lever guard cam;
  • Figure 3b is a section on the line 3-3 of Figure 3a;
  • Figure 4a is a side view of the lever guard
  • Figure 4b is an end view of the lever guard
  • Figure 5a is a side view of the operating lever cam
  • Figure 5b is a section on the line 5-5 of Figure 5a;
  • Figure 6a is a side view of the operating lever
  • Figure 6b is an end view of the operating lever
  • a chain saw typically comprises a housing part (10) which provides a grip (11) for the right-hand of an operator and a grip (12) for the left-hand of an operator.
  • a switch (14) which is manually operable to close an electrical circuit to a motor disposed in the housing.
  • the motor is disposed in a housing part (15) which is located beneath the grip (12).
  • a guard (16) which includes a pivotably mounted arm (17) is disposed forwardly of the grip (12). This guard has to be located in its operative condition before the saw can be operated.
  • the saw (19) extends forwardly from the housing and can be energised from the motor when the guard (17) is in its operative position and the switch (14) is closed.
  • FIG. 2 of the drawings there is shown a moulded housing (30) from which projects the chain saw (31).
  • the moulded housing has towards its rear end an opening (32) which defines a hand grip for the right-hand of an operator.
  • a lever (34) is pivotally mounted on the housing at (35) so that a part of its body projects into the housing opening (32) and can be moved by the right-hand of an operator holding the grip.
  • the motor which is not shown, has a shaft (36) which extends laterally of the housing and carries a circular drum or disc (37).
  • a braking band (38) extends around the periphery of the disc.
  • the band is formed from a strip of resilient material and extends in a generally circular path around the disc so that opposite end portions of the strip extend substantially tangentially from a common circumferential point on the circular path.
  • One end portion (40) of the band namely that extending to the left when viewed in Figure 1, is bent around into a generally cylindrical form (41) with the extreme end edge (42) extending in juxtaposition to the portion (40) and being secured thereto by suitable means such as welding.
  • the cylindrical part (41) defines a stop.
  • the other end portion (45) has a folded overpart (46) which projects tangentially from the circular path of the band and a curved part (48) which extends in a semicylindrical path from the folded overpart to abut the stop (41).
  • the curvature of the curved part (48) is such that by virtue of its abutment with the stop (41) the natural resilience of the material of the band urges the circular part of the band to a position of reducing diameter, that is to say its natural position is one in which it grips tightly around the disc (37).
  • a moulded part (50) Internally of the housing there is provided a moulded part (50) which defines a generally tubular passage for a plurality of balls (52).
  • the passage has a generally horizontal part (51) which extends from a position close to the braking band towards the front of the housing.
  • the moulded part (50) At the front of the housing the moulded part (50) has an upwardly extending open mouth part (53) and two longitudinally spaced downwardly extending open mouth parts (54 and 55).
  • the internal wall of the horizontal part has a downwardly projecting dimple (56).
  • a transverse shaft (60) This shaft carries two cam members, parts of which are disposed concentrically about the shaft.
  • a first cam member (61) is associated with a lever (62) which carries at its upper end a guard (63).
  • the cam member (61) (see also Figure 3) has a tubular part (65) one end of which is provided with angularly spaced circumferentially extending recesses (66).
  • the other end of the tubular part is formed integrally with a generally disc-like portion (68), the disc-like portion (68) defining a profiled recess (69) which receives one end of a spring (70), the other end of which is pivotally mounted relative to the housing.
  • the spring (70) acts as an overcentre device.
  • the disc-like part (68) also is formed to define a nose (72) disposed adjacent the upwardly extending open mouth part (53).
  • the disc-like part (68) carries an axially spaced portion (74) which defines a shoulder (75) which is located in the open mouth part (55) .
  • the lever guard (62) has a lower cylindrical part (80) which is disposed coaxially with the shaft (60).
  • the cylindrical part (80) is formed with internal recesses (81) which are so arranged that they can mate with the non-recessed parts of the tubular part (65) of the cam (61), whereby the lever and cam can interengage so that pivoting movement of the lever results in rotation of the cam (61) about the shaft (60).
  • the lever also has an upwardly extending gently curving part (82) and the guard is formed by two horizontal limbs (83 and 84) linked by an integrally formed leg (85) .
  • the second cam (62) is associated with an operating lever (90).
  • the second cam member (see Figure 5) includes a tubular part (91) disposed coaxially within the tubular part (65) of the first cam member (61).
  • One end of the tubular part has angularly spaced circum erentially extending notches (92) and the other end of the tubular member is formed with a generally disc-like part (93).
  • the disc-like part carries an axially spaced portion (94) which defines a shoulder (96) located in the downwardly extending open mouth part (54).
  • the disc-like part (92) also has an opening (95).
  • the operating lever (90) (see Figure 6) has a lower disc-like part (96) which is formed with a through opening (98).
  • the shaft (60) extends through the opening (98) and the walls of the opening are formed with recesses (97) which are so located that the non-recessed parts can cooperate with the recesses on the tubular part of the cam (62) in a manner similar to that described with reference to the first cam (61).
  • pivoting movement of the lever (90) is transmitted to the cam (62) to rotate the cam about the shaft (60).
  • the operating lever (90) also includes a generally upwardly extending curved part (99) which terminates in a horizontally extending arm (100) disposed forwardly of the left-hand grip (101) mounted on the housing (30).
  • the arm (100) is so disposed that it can be gripped using the fingers of the hand holding the grip (101).
  • a generally cylindrical plunger (110) is located in one end of the tubular passage defined by the housing part (50).
  • the plunger (see also Figure 2b), has two parts (110a) and (110b) which are biassed apart axially by a spring (112).
  • the body part (110a) has at one end a diametrically extending slot (111) which receives the folded over portion (46) of the braking band.
  • the plunger (110) is mounted so that it can slide axially within the tubular passage.
  • a plurality of balls (52) are also disposed in the passage. In Figure 2 the balls are shown in the non-energised position of the mechanism.
  • the housing also carries a further lever (120) which is pivotally mounted to the housing at (121).
  • the lever (120) extends from a position adjacent the inner end of the lever (34) and terminates at its other end in a curved nose portion (124), which defines a face (125) disposed adjacent the ball which is located in the upwardly extending mouth part (53).
  • the lever (120) is so mounted that when the lever (34) is gripped to move it upwardly, the nose part of the lever (120) is caused to move downwardly.
  • the lever (120) also carries at its pivot point a projecting nose member (126) which is disposed in a recess defined by the curved head part of a spring member (130).
  • the head member (131) of the spring is generally dome-shaped and terminates in a lip (132) which normally rests against the upper part of the lever (120).
  • the spring also has a long gradually curved back portion (134) which extends downwardly from the head part (131) and terminates at its lower end in a rounded projection (135) which is received in the opening (95) -formed in the disc-like part (93) of the operating lever cam (62). It will be seen that the curved back portion extends in close proximity to the nose (72) formed on the guard cam.
  • a microswitch (140) is mounted within the housing above the lip (132) of the spring (130).
  • the actuating member (141) of the microswitch projects downwardly towards the lip.
  • the microswitch is connected into the energising circuit of the motor of the chain saw, such that the motor cannot be energised until the microswitch contacts are closed by movement of the actuating member of the microswitch.
  • the starting point is the condition shown in Figure 2 of the drawings.
  • the plunger (110) is at its axially innermost position with the ball passage (51) of the housing (50) so that the braking band (38) is engaged tightly about the disc (37) .
  • the spring (112) ensures that the body part (110b) is maintained against the endmost ball, that is to say the balls are urged to the right in Figure 2.
  • the lip (132) of the spring. (130) is spaced from the actuating member (141) of the microswitch and hence the contacts of the microswitch are in an open circuit condition. This means that electrical power cannot be applied to the motor of the saw.
  • the first step is to set the lever guard (62). This is achieved by pulling the lever guard rearwardly so that it pivots about the shaft (60) . This movement causes rotation of the guard cam (61) so that the spring (70) is moved overcentre to the position shown in Figures 7 and 7a. In this position the spring (70) is operative to retain the cam (61) in that position.
  • the rotary movement of the cam (61) results in the shoulder (75) of the cam moving upwardly into the mouth part (55) and forcing the ball which was in that mouth part to move into the horizontal part (51) of the ball passage.
  • the third step in the sequence is to squeeze the lever (34) of the grip (32) so that that lever moves upwardly and causes the nose (124) of the lever (120) to move into the upwardly open mouth (53) of the ball passage (see Figure 9).
  • This movement causes the ball which was in that open mouth to move downwardly, thereby displacing the plunger (110) a further distance axially within the ball passage (51).
  • This final movement of the plunger (110) is sufficient to move the braking band (38) to a condition in which it is clear of and no longer firmly engages the disc (37). The effect of this is to release the braking action on the disc.
  • the present actuating mechanism requires a three step operation before the chain saw is energised.
  • the guard (62) has to be set, the operating lever (90) has to be moved rearwardly and the lever (34) associated with the grip (32) has to be squeezed. Only when all three operations are effected can the chain saw be energised.
  • the dimple (56) is provided to ensure that the ball above the mouth part (54) cannot become locked against the adjacent balls in the ball passage. As has been explained this ball is disposed slightly lower than the adjacent balls and will therefore fall naturally into any space created in the mouth part (54).
  • the actuating mechanism described above has a number of safety features inherent in it. Its arrangement is such that the tool which is arranged to operate can only be energised following a three step operation. Furthermore, if the reverse of any of one of those three steps occurs, motive power for the tool is immediately cut off and a brake immediately applied to the output shaft of the motor.
  • the form of the braking band is constructed from a single strip of material and it is so formed that it is effectively self-energising. Thie eliminates the cost of an extra component such as a separate stop.
  • mouth parts (53 to 55) are shown in a common plane. It will be appreciated that they can be arranged to extend at any suitable orientation to the ball passage to suit the particular application.
  • microswitch can be replaced by any suitable switch such as a double pole switch.
  • the lever (34) and lever (120) could be replaced by a single lever.
  • the actuating mechanism described above has three manually operable members (34, 62, 90), all of which require operation in order to energise the drive means of the chainsaw. It will be appreciated that the mechanism can be used with tools where a different number of operating members are employed.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Harvester Elements (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Sawing (AREA)
  • Braking Arrangements (AREA)
  • Pinball Game Machines (AREA)

Abstract

Mécanisme actionneur pour outil à moteur tel qu'une tronçonneuse.Il comporte un ou plusieurs éléments (34, 62, 90) actionnés à la main et montés sur le carter (30) de l'outil. Un mécanisme de freinage (37, 38) est associé au dispositf d´entraînement de l'outil et assure normalement le freinage de ce dispositif d'entraînement. Les éléments (34, 62, 90) actionnés à la main sont couplés au mécanisme de freinage (37, 38) par l'intermédiaire d'une pluralité de billes (52) disposées dans un passage de telle sorte que tout déplacement de chaque élément provoque un certain déplacement des billes (52). Lorsqu'un nombre prédéterminé d'éléments sont actionnés, le freinage s'interrompt.
PCT/GB1993/002584 1992-12-17 1993-12-17 Mecanisme de securite pour outil a moteur Ceased WO1994013441A2 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU57067/94A AU5706794A (en) 1992-12-17 1993-12-17 Safety mechanism for power tool
FI952988A FI952988A7 (fi) 1992-12-17 1993-12-17 Konekäyttöisen työvälineen varmuusmekanismi
EP94902894A EP0675786A1 (fr) 1992-12-17 1993-12-17 Mecanisme de securite pour outil a moteur
NO952389A NO952389L (no) 1992-12-17 1995-06-16 Sikkerhetsmekanisme for motordrevet verktöy

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9226261.7 1992-12-17
GB9226261A GB2273753B (en) 1992-12-17 1992-12-17 Safety mechanism for power tool

Publications (2)

Publication Number Publication Date
WO1994013441A2 true WO1994013441A2 (fr) 1994-06-23
WO1994013441A3 WO1994013441A3 (fr) 1994-08-04

Family

ID=10726730

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/002584 Ceased WO1994013441A2 (fr) 1992-12-17 1993-12-17 Mecanisme de securite pour outil a moteur

Country Status (9)

Country Link
EP (1) EP0675786A1 (fr)
AU (1) AU5706794A (fr)
CA (1) CA2151908A1 (fr)
FI (1) FI952988A7 (fr)
GB (1) GB2273753B (fr)
HU (1) HUT72503A (fr)
NO (1) NO952389L (fr)
PL (1) PL309397A1 (fr)
WO (1) WO1994013441A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12064894B2 (en) 2020-09-04 2024-08-20 Milwaukee Electric Tool Corporation Chainsaw
US12370714B2 (en) 2021-09-08 2025-07-29 Techtronic Cordless Gp Systems and methods for chainsaw lubricant delivery control

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19812861B4 (de) * 1998-03-24 2007-07-05 Robert Bosch Gmbh Elektrokettensäge
US8008812B2 (en) 2006-07-14 2011-08-30 Aurora Office Equipment Co., Ltd. Paper shredder control system responsive to touch-sensitive element

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1298988A (en) * 1970-03-20 1972-12-06 British Domestic Appliances Improvements in or relating to spin driers
US3793727A (en) * 1972-10-04 1974-02-26 Mcculloch Corp Chain saw safety method and apparatus
US4335514A (en) * 1980-08-08 1982-06-22 Black & Decker Inc. Switch-brake interlock for chain saw
DE3211577C2 (de) * 1982-03-29 1984-12-13 Siemens AG, 1000 Berlin und 8000 München Bremseinrichtung für eine Kabeltrommel
DE3430840A1 (de) * 1984-08-22 1986-03-06 Fa. Andreas Stihl, 7050 Waiblingen Motorkettensaege
US5118229A (en) * 1991-06-04 1992-06-02 Kennametal Inc. Apparatus for transmitting motion to an off-axis rotary driven tool

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12064894B2 (en) 2020-09-04 2024-08-20 Milwaukee Electric Tool Corporation Chainsaw
US12370714B2 (en) 2021-09-08 2025-07-29 Techtronic Cordless Gp Systems and methods for chainsaw lubricant delivery control

Also Published As

Publication number Publication date
HU9501761D0 (en) 1995-08-28
NO952389D0 (no) 1995-06-16
HUT72503A (en) 1996-05-28
FI952988L (fi) 1995-08-16
CA2151908A1 (fr) 1994-06-23
GB2273753A (en) 1994-06-29
AU5706794A (en) 1994-07-04
EP0675786A1 (fr) 1995-10-11
FI952988A0 (fi) 1995-06-16
GB2273753B (en) 1996-03-27
FI952988A7 (fi) 1995-08-16
PL309397A1 (en) 1995-10-02
NO952389L (no) 1995-06-16
GB9226261D0 (en) 1993-02-10
WO1994013441A3 (fr) 1994-08-04

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