EP1669165A1 - Kraftwerkzeug mit gedämpften Schwingungen - Google Patents

Kraftwerkzeug mit gedämpften Schwingungen Download PDF

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Publication number
EP1669165A1
EP1669165A1 EP04257603A EP04257603A EP1669165A1 EP 1669165 A1 EP1669165 A1 EP 1669165A1 EP 04257603 A EP04257603 A EP 04257603A EP 04257603 A EP04257603 A EP 04257603A EP 1669165 A1 EP1669165 A1 EP 1669165A1
Authority
EP
European Patent Office
Prior art keywords
tool according
housing
resilient members
axis
stator
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Withdrawn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
EP04257603A
Other languages
English (en)
French (fr)
Inventor
Mark Avis
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.)
Black and Decker Inc
Original Assignee
Black and Decker Inc
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 Black and Decker Inc filed Critical Black and Decker Inc
Priority to EP04257603A priority Critical patent/EP1669165A1/de
Priority to EP05823613A priority patent/EP1971463A1/de
Priority to PCT/EP2005/056523 priority patent/WO2006061385A1/en
Publication of EP1669165A1 publication Critical patent/EP1669165A1/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D17/24—Damping the reaction force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
    • B25D2250/091—Electrically-powered tool components
    • B25D2250/095—Electric motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
    • B25D2250/371—Use of springs
    • B25D2250/381—Leaf springs

Definitions

  • the present invention relates to power tools and relates particularly, but not exclusively, to percussive power drills.
  • Power drills for drilling masonry are known in which a percussive action is imparted to the drill bit by means of cooperating ratchet plates on a shaft supporting the drill bit and a body of the drill relative to which the shaft rotates. As the cooperating ratchet plates rotate relative to each other, the ratchet plate on the shaft supporting the drill bit is provided with an axial impulse, which is transmitted to the drill bit.
  • Percussive drills of this type suffer from the drawback that the interaction of a drill bit of such a drill with masonry being drilled generates significant vibrations, which can be detrimental to the health of users of the drill over prolonged periods of use.
  • Such vibrations generally include a high frequency component caused by the vibration of the ratchet plates, typically in the region of 580 Hz, and a low frequency component caused by vibration of a drill bit of the drill in a hole being formed by the drill.
  • the low frequency components of vibration typically 10 - 20 Hz
  • standards relating to hand-arm vibration use weighting factors to describe the level of vibration likely to cause injury.
  • a mathematical filter equation is used which emphasises frequencies closest to the 10 - 20 Hz band, but duration of exposure as well as instantaneous vibration level is taken into account.
  • Preferred embodiments of the present invention seek to overcome the above disadvantages of the prior art.
  • a power tool comprising:-
  • Said first vibration attenuating means may comprise a plurality of resilient members.
  • Said first vibration attenuating means may act between a bearing of said rotor and said housing.
  • the tool further comprises a gearbox connected to said motor, and said first vibration attenuating means acts between said gearbox and said housing.
  • the tool may comprise a plurality of first said resilient members and a plurality of second said resilient members, wherein said first and second resilient members are circumferentially spaced about said first axis, and said first resilient members are circumferentially offset relative to said second resilient members.
  • Said first and second resilient members may be arranged substantially perpendicularly to said first axis.
  • the tool may further comprise at least one third said resilient member arranged substantially parallel to said first axis.
  • This provides the advantage of enabling the stiffness of the tool along the first axis to be increased to prevent the tool from becoming too compliant in an axial direction.
  • At least one said resilient member may have adjustable resilience.
  • At least one said resilient member may comprise a respective spring acting against a respective abutment having adjustable position.
  • the tool may further comprise second vibration attenuating means for attenuating vibrations transmitted from said stator to said housing in a direction substantially parallel to said first axis.
  • this provides the surprising advantage of much more effectively reducing the level of vibration transmitted to the hands of a user of the tool, and is especially effective in reducing transmission of the high frequency components typically caused by ratchet plates of a percussive power drill.
  • the further advantage is provided that forces can be more effectively transmitted into a workpiece, with the effect that a power drill having ratchet plates to impart a hammer action to a drill bit operates more effectively for a given ratchet plate profile.
  • the stator is displaceable relative to said housing in a direction substantially parallel to said first axis
  • the second vibration attenuating means comprises biasing means for resisting said displacement of said stator relative to said housing at least in a direction substantially parallel to said first axis.
  • the second vibration attenuating means acts between said stator and a support.
  • Said biasing means may comprise at least one further resilient member.
  • Said biasing means may comprise a plurality of first said further resilient members circumferentially spaced around said first axis and a plurality of second said further resilient members offset from said first further resilient members in a direction parallel to said first axis.
  • Said first further resilient members may be circumferentially offset relative to said second further resilient members.
  • At least one said further resilient member may comprise at least one respective leaf spring.
  • the resilience of at least one said further resilient member may be adjustable.
  • This provides the advantage of enabling the frequency at which vibrations are most effectively attenuated to be adjusted, which in turn enables the resilience of the second vibration attenuating means to be tuned, for example, to the frequency of operation of ratchet plates of a percussive drill.
  • At least one said leaf spring comprises a plurality of removable spring members.
  • leaf spring comprising a plurality of removable members, for example in the form of a set of multiple laminations of spring plates, this provides the advantage of enabling the resilience of the second vibration attenuating means to be easily adjusted.
  • the second vibration attenuating means may comprise a plurality of interchangeable said further resilient members having different resiliencies.
  • a power drill 2 has a housing 4 incorporating a motor 6 for driving an output shaft 8 via a gearbox 10, in a manner which will be familiar to persons skilled in the art.
  • the output shaft 8 carries a chuck 12 to which a drill bit (not shown) is mounted, and cooperating ratchet plates (not shown) contained within the gearbox 10 are connected to an output gear of the gearbox 10 and to the output shaft 8 respectively, to impart a percussive action to the chuck 12 as they are rotated relative to each other as a result of rotation of the output shaft 8 relative to the housing 4.
  • Rotation of the output shaft 8 is caused by actuation of the motor 6, which is powered by squeezing a trigger 18 provided on a handle 20.
  • the drill 2 is also provided with a further handle 22.
  • the motor 6 comprises a stator 24 and a rotor 26, the rotor 26 being mounted to rear 28 and front 30 bearings so that the rotor 26 can rotate about axis 32 relative to stator 24.
  • the rotor 26 also carries a fan 34 for generating air flow to cool the motor 6 in a manner which will be familiar to persons skilled in the art.
  • the stator 24 is mounted to a support 36 by means of a vibration attenuating means in the form of two sets of three leaf springs 38 spaced equiangularly about the rotation axis 32 of rotor 26 and arranged at opposite axial ends of the stator 24 (only one set of leaf springs 38 being shown in Figures 5 and 6).
  • Each set of leaf springs 38 is clamped to an end of the stator 24 by means of a respective end plate 40, and each leaf spring 38 is formed from multiple removable laminate sections, so that the spring force of each leaf spring 38 can be adjusted by adding or removing laminate sections.
  • the leaf springs 38 at the opposite ends of the stator 24 are offset from each other by approximately 60 degrees.
  • stator 24 can move axially relative to support 36, but torsional movement of the stator 24 relative to the support 36 is minimised.
  • leaf springs 38 serve to absorb the high frequency component of vibrations, which is generally caused by vibration of the ratchet plates in gearbox 10, and is typically near to 580 Hz.
  • the support 36 is rigidly mounted to rear shaft bearing 28 and to forward shaft bearing 30 by means of screws (not shown).
  • the rear bearing 28 is then mounted to the housing 4 by means of a set of three equiangularly spaced compression springs 42.
  • Each of the springs 42 is located in a spring cup 44, and the spring cups 44 are threaded and located in respective sleeves 46 ( Figures 1 and 2) in the housing 4 to allow adjustment of the pre-loading of springs 42, which in turn adjusts the resonant frequency of oscillation of the motor 6 relative to the housing 4.
  • the forward bearing 30 is mounted to the housing 4 by means of three equiangularly arranged compression springs 48, which are offset at approximately 60 degrees relative to compression springs 42, and which in turn are located in respective spring cups 50 which are threaded and located in respective sleeves 52 in housing 4 to allow adjustment of the pre-loading of the springs 48.
  • the springs 42, 48 form a further vibration attenuating means, for minimising the transmission of vibrations from the motor 6 to the housing while avoiding making the drill bit (not shown) too compliant relative to the housing 4. It is found that the springs 42, 48 are particularly effective in attenuating both the low and high frequency components of vibration caused by vibration of the drill bit in a hole being drilled.
  • one or more compression springs can be arranged along axis 32 between the rear portion of the motor 6 and the housing 4. This avoids the drill bit becoming too compliant relative to the housing 4 in an axial direction, ensuring that the steady application of force by the user onto a masonry workpiece results in acceptable axial spring displacement.
  • Figure 7 shows the modulus of hand-arm velocity reduction for the user of the drill, compared with ratchet input velocity, from which it can be seen that by suitably adjusting the spring force of springs 38, 42, 48, the transmission of vibrations to the user's hand is minimised at a ratchet plate frequency of 580 Hz.
  • Figure 8 shows the modulus of force applied to a masonry load by the drill 2 of Figures 1 to 6 compared to ratchet input velocity. At the relevant frequency of 580 Hz, it can be seen that the force delivered to the load is increased, while the vibrations transmitted to the user are decreased. It can therefore be seen that the drill 2 enables more effective operation of the drill for a given ratchet plate profile to be achieved, which minimises the effect of vibrations on the user.
  • the present invention uses the principle of dynamic absorption to minimise the transmission of harmful vibrations to the user.
  • the high frequency vibrations at the ratchet plates act predominantly along the rotation axis 32, as a result of which the high frequency vibrations can be effectively attenuated by allowing limited axial movement of the motor stator 24 relative to the housing.
  • the more harmful low frequency vibrations are caused predominantly by vibration of the drill bit in a hole being drilled in masonry, and produce components of low frequency vibration along all three axes, i.e. both along and perpendicularly to the axis 32.
  • the low frequency vibrations are attenuated by springs 42, 48, which allow damped movement of the drill bit relative to the housing in all three directions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Drilling And Boring (AREA)
  • Percussive Tools And Related Accessories (AREA)
EP04257603A 2004-12-07 2004-12-07 Kraftwerkzeug mit gedämpften Schwingungen Withdrawn EP1669165A1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP04257603A EP1669165A1 (de) 2004-12-07 2004-12-07 Kraftwerkzeug mit gedämpften Schwingungen
EP05823613A EP1971463A1 (de) 2004-12-07 2005-12-06 Schwingungsgedämpftes, kraftbetriebenes werkzeug
PCT/EP2005/056523 WO2006061385A1 (en) 2004-12-07 2005-12-06 Vibration attenuated power tool

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP04257603A EP1669165A1 (de) 2004-12-07 2004-12-07 Kraftwerkzeug mit gedämpften Schwingungen

Publications (1)

Publication Number Publication Date
EP1669165A1 true EP1669165A1 (de) 2006-06-14

Family

ID=34930890

Family Applications (2)

Application Number Title Priority Date Filing Date
EP04257603A Withdrawn EP1669165A1 (de) 2004-12-07 2004-12-07 Kraftwerkzeug mit gedämpften Schwingungen
EP05823613A Withdrawn EP1971463A1 (de) 2004-12-07 2005-12-06 Schwingungsgedämpftes, kraftbetriebenes werkzeug

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP05823613A Withdrawn EP1971463A1 (de) 2004-12-07 2005-12-06 Schwingungsgedämpftes, kraftbetriebenes werkzeug

Country Status (2)

Country Link
EP (2) EP1669165A1 (de)
WO (1) WO2006061385A1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7413026B2 (en) 2006-07-01 2008-08-19 Black & Decker Inc. Lubricant system for powered hammer
AU2007202967A1 (en) 2006-07-01 2008-01-17 Black & Decker, Inc. A tool holder for a pavement breaker
JP2008012661A (ja) 2006-07-01 2008-01-24 Black & Decker Inc ハンマードリル用のビートピース磨耗表示器

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2154497A (en) * 1984-02-18 1985-09-11 Bosch Gmbh Robert Hand machine tool, particularly hammer drill or percussion drill
US4609053A (en) * 1982-09-22 1986-09-02 Atlas Copco Aktiebolag Hammer tool
EP0336261A2 (de) * 1988-03-29 1989-10-11 Politechnika Poznanska Vibrationsschutzvorrichtung zwischen den Elementen eines Handwerkszeuges
DE4000861A1 (de) * 1990-01-13 1991-07-18 Licentia Gmbh Handgefuehrte elektrowerkzeugmaschine
AU651269B2 (en) * 1991-12-17 1994-07-14 Ingersoll-Rand Company Apparatus for reducing vibration transmission in hand-held tool
DE20109122U1 (de) * 2001-05-31 2001-08-02 Wacker Werke Kg Motorisch angetriebener Hammer mit einer gegen das Hammergehäuse abgefederten Schutzhaube
US6318479B1 (en) * 1999-10-01 2001-11-20 Chicago Pneumatic Tool Company Vibration isolated impact wrench
US20040154813A1 (en) * 2002-11-22 2004-08-12 Christian Daubner Vibration-decoupling arrangement for supporting a percussion unit in a hand-held percussion power tool

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4609053A (en) * 1982-09-22 1986-09-02 Atlas Copco Aktiebolag Hammer tool
GB2154497A (en) * 1984-02-18 1985-09-11 Bosch Gmbh Robert Hand machine tool, particularly hammer drill or percussion drill
EP0336261A2 (de) * 1988-03-29 1989-10-11 Politechnika Poznanska Vibrationsschutzvorrichtung zwischen den Elementen eines Handwerkszeuges
DE4000861A1 (de) * 1990-01-13 1991-07-18 Licentia Gmbh Handgefuehrte elektrowerkzeugmaschine
AU651269B2 (en) * 1991-12-17 1994-07-14 Ingersoll-Rand Company Apparatus for reducing vibration transmission in hand-held tool
US6318479B1 (en) * 1999-10-01 2001-11-20 Chicago Pneumatic Tool Company Vibration isolated impact wrench
DE20109122U1 (de) * 2001-05-31 2001-08-02 Wacker Werke Kg Motorisch angetriebener Hammer mit einer gegen das Hammergehäuse abgefederten Schutzhaube
US20040154813A1 (en) * 2002-11-22 2004-08-12 Christian Daubner Vibration-decoupling arrangement for supporting a percussion unit in a hand-held percussion power tool

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"HALTING POWER TOOL HAMMER BLOWS HURTING THE USER", DESIGN ENGINEERING, MORGAN-GRAMPIAN LTD. LONDON, GB, 1 June 1992 (1992-06-01), pages 9, XP000305350, ISSN: 0308-8448 *

Also Published As

Publication number Publication date
WO2006061385A1 (en) 2006-06-15
EP1971463A1 (de) 2008-09-24

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