US20050257944A1 - Handle assembly for tool - Google Patents

Abstract

A handle assembly for a power tool1comprises a housing2defining a handle4and housing a motor for actuating an output member of the tool, such as a drill bit or jigsaw blade. The handle assembly comprises at least one flexible sheet8adapted to be mounted to a surface of the handle of the power tool and having a series of protrusions10adapted to be engaged by a hand of a user of the tool. The protrusions10retain one or more blister packs (not shown) containing at least one vibration damping gel material between the flexible sheet8and the surface of the handle4.

Description

FIELD OF THE INVENTION
• The present invention relates to handle assemblies for tools, and relates particularly, but not exclusively, to handle assemblies having combined friction gripping and vibration damping properties, for power tools in which an output shaft is driven by a motor.
BACKGROUND OF THE INVENTION
• Known power tools, such as power drills in which a drill bit is rotated by an output shaft which is in turn rotated by means of an electric motor, generate significant amounts of vibration, which can under certain circumstances limit the length of time during which the tool can be used continuously. In addition, the housing of such tools is generally made from a durable plastics material on which it can be difficult for a user of the tool to maintain a grip when the tool is in use for a sustained period.
• U.S. Pat. No. 6,308,378 discloses a gripping arrangement for a handle of a power tool in which the sides of the handle are provided with frictional gripping zones, each side of the handle including a plurality of alternating gripping zones of a softer material and a harder material. The softer material used is generally a thermoplastic elastomer or rubber material, and the harder material is generally the same material as that from which the tool housing is formed.
• This known arrangement suffers from the drawback that because the softer material performs the dual functions of providing a friction grip and vibration damping, the choice of material constitutes a compromise in that although it will have acceptable friction reducing and vibration damping properties, the performance of the handle is limited because a material having optimum frictional properties will generally have unacceptable vibration damping properties, and vice versa.
• WO02/38341 discloses a grip handle for a hand-held machine tool in which a hand grip is separated from the remainder of the housing by a vibration damping element consisting of an inflatable annular air filled cushion. An additional handle is provided which has a tubular grip element surrounding a further annular air cushion.
• This known arrangement suffers from the drawback that the vibration damping properties of air can only be varied by adjusting the air pressure within a chamber containing the air, and even then, the range of vibration damping properties achievable is limited. Furthermore, it is difficult, and therefore expensive, to manufacture a sealed chamber containing air having a predetermined pressure.
• Preferred embodiments of the present invention seek to overcome the above disadvantages of the prior art.
BRIEF SUMMARY OF THE INVENTION
• According to an aspect of the present invention, there is provided a gripping portion for a power tool having a housing and a motor within said housing for actuating an output member of the tool, the gripping portion adapted to be engaged by a hand of a user of the tool and comprising:
• • at least one blister pack comprising respective first and second flexible sheets defining at least one gel-containing chamber therebetween, wherein the or each said gel-containing chamber contains a vibration damping gel material and said first and second sheets are sealed to each other at the periphery of the or each said gel containing chamber; and
  • at least one clamping member for clamping at least one said blister pack to said housing and having at least one aperture therethrough such that at least one said gel-containing chamber protrudes in use through a respective said aperture and substantially none of said vibration damping gel is located in use between a said clamping member and the housing.
• By providing at least one flexible member and at least one chamber containing at least one vibration damping gel material between the engaging portion and the surface of the handle in use, this provides the advantage of enabling the material of the flexible member to be chosen to have the optimum frictional properties to enable a user to maintain a grip on the tool, and the vibration damping gel material at the same time to have the optimum vibration damping properties. In particular, it is possible to provide gel materials having a wide range of vibration damping properties compared with air. This also provides the advantage of simplifying construction of the assembly, which in turn reduces the cost of manufacture of the assembly, as well as providing the advantage of further reducing the cost of manufacture of the assembly by providing one or more components which perform more than one function.
• At least one said blister pack may be foldable.
• This provides the advantage of enabling the blister pack to conform to the shape of the tool handle.
• At least one said blister pack may be perforated between at least one pair of adjacent chambers.
• This provides the advantage of facilitating folding of the blister pack.
• At least one said blister pack may further comprise locating means for enabling the blister pack to be mounted to a support.
• Said locating means may comprise at least one aperture through said blister pack at a respective location remote from the or each said chamber.
• The assembly may further comprise support means adapted to be located on a side of at least one said blister pack remote from the corresponding said engaging portion.
• At least one said chamber containing the or each said gel material may be at least partially transparent in use.
• This provides the advantage of enabling visible indicia, such as decorative features or trade marks, or electrical indicators, for example indicating that the tool of which the assembly forms part is actuated, to be seen while the tool is in use.
• The assembly may further comprise at least one visible indicium located in at least one said chamber.
• At least one said visible indicium may be electrically operated in use.
• This provides the advantage of enabling said indicium to provide an indication of an operating condition of a power tool, such as whether the tool is actuated.
• At least one said indicium may be at least one light emitting diode.
• The assembly may further comprise at least one electrical switch for actuating the tool.
• This provides the advantage of simplifying assembly of the tool, which in turn further reduces the cost of manufacture of the tool.
• According to another aspect of the present invention, there is provided a tool comprising:
• • a housing;
  • a motor within the housing adapted to actuate an output member of the tool; and
  • a gripping portion as defined above.
• Said gripping portion may have an outer surface including at least one material of higher coefficient of friction than the material of the housing of the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
• Preferred embodiments of the invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:
• FIG. 1 is a perspective view of part of a housing of a power tool of a first embodiment of the present invention;
• FIG. 2 is an exploded perspective view of the housing of the embodiment ofFIG. 1;
• FIGS. 3A to3C show side cross-sectional views of three alternative forms of gel blister pack for use in the embodiment ofFIGS. 1 and 2;
• FIG. 4A is a side view of a handle assembly of a power tool of a second embodiment of the present invention;
• FIG. 4B is a rear view of the handle assembly ofFIG. 4A;
• FIG. 4C is a perspective view of the handle assembly ofFIG. 4AFIG. 4D is a partial cross-sectional view showing the relation between the gel piece and the handle for the power tool shown in FIGS.4A-C.
• FIG. 4E is a side view showing an alternative embodiment of the power tool shown inFIG. 4A.
DETAILED DESCRIPTION OF THE INVENTION
• Referring toFIGS. 1 and 2, a power tool1 such as a drill or jigsaw comprises ahousing2 defining anaperture3 bounded on one side thereof by ahandle4, thehousing2 containing a motor (not shown) for actuating an output member such as a drill bit or jigsaw blade (not shown).
• Thehousing2 is formed from a generally durable plastics material, as will be familiar to persons skilled in the art, and has a recessed portion5 on a generally smooth upper surface of thehandle4, the recessed portion5 being provided with arecess6 containing an actuating switch (not shown) for turning the tool1 on and off. Thehousing2 is provided withventilation apertures7 at one end of the recessed portion5 to allow cooling of the interior of thehousing2.
• Aflexible sheet8, of thermoplastic elastomeric material, such as a thin layer of polyurethane, having a coefficient of friction higher than that of the material from which thehousing2 is made, is formed by means of a suitable method such as moulding. Thesheet8 has a periphery shaped to fit inside the periphery of recessed portion5 to cover all of the recessed portion5 except that part in which theventilation apertures7 are provided, and theflexible sheet8 is provided with a through-aperture9 to allow access to the actuating switch inrecess6. Theflexible sheet8 is also provided with a series ofprotrusions10, each of which defines a chamber between thesheet8 and the upper surface of thehandle4 of thehousing2 when thesheet8 is placed in position on the upper surface of the recessed portion5. Each of the chambers underneath theprotrusions10 accommodates a vibration damping gel contained in a blister pack20 (FIGS. 3A to3C). Alternatively, theflexible sheet8 may be bonded to a backing sheet (not shown) to define the chambers containing the vibration damping gel.
• A cover plate11 of durable plastics material, such as the material from which thehousing2 is constructed, has aninternal surface12 corresponding generally to the external (i.e. upper) surface of theflexible sheet8. The cover plate11 is provided with a series offirst apertures13 for allowing theprotrusions10 of thesheet8 to protrude therethrough when the plate11 is mounted to thehandle4 to secure theflexible sheet8 in place, asecond aperture14 co-operating with the aperture9 to allow access to the actuating switch inrecess6, and a series ofthird apertures15 cooperating with theventilation apertures7 in thehousing2.
• Referring now toFIG. 3A, agel blister pack20 for use in the embodiment ofFIGS. 1 and 2 is formed from a thin,flexible backing piece21 of thermoplastic polyurethane film on which one ormore pieces22 of a vibration damping gel formed from a semi-solid silicone rubber or polyurethane material are provided. Thepieces22 of gel may be translucent and/or semi transparent and/or coloured, for reasons which will be explained in greater detail below. Thebacking layer21 with thepieces22 of gel are then covered by a generallytransparent layer23 of thin, thermoplastic polyurethane film, which is pulled down tightly over thegel pieces22 by means of a combination of heat and pressure, and then secured to thebacking piece21 at theperiphery24 of eachgel piece22 to form discrete chambers encapsulating each gel piece by suitable welding techniques, such as heat staking and/or ultrasonic vibration, which will be familiar to persons skilled in the art. Alternatively, thegel material22 can be poured or injected into a pre-formedtransparent sheet23 and then covered by backingpiece21 and welded. The upper surface of thebacking piece21 may be printed with decorative or trade mark information which is visible through thetransparent layer23 andgel22.
• Referring toFIG. 3B, in which parts common to the embodiment ofFIG. 3A are denoted by like reference numerals but increased by100 and will therefore not be described in greater detail herein, thebacking piece121 of theblister pack120 is provided with a series of raisedportions125 which may be decorative matter and/or trade marks or raised lettering. The raisedportions125 define recesses126, which may accommodate light emitting diodes which can be illuminated to provide a visual indication of an operating parameter of the tool incorporating theblister pack120, for example to indicate whether the tool is switched on.
• In the arrangement ofFIG. 3C, in which parts common to the embodiment ofFIG. 3B are denoted by like reference numerals but increased by100, the raisedportions225 definingrecesses226 may be formed by aseparate layer227, which is encapsulated along withgel material222 bytransparent sheet223 andbacking piece221.
• The operation of thehandle4 of the tool1 of FIGS.1 to3 will now be described.
• When a user's hand (not shown) grips the tool1 when in use, the user's hand comes into contact with the cover plate11 and theprotrusions10 beneath which one ormore blister packs20,120,220 containing vibration damping gel are located. As a result, vibrations generated by the motor in thetool housing2 are damped by the vibration damping gel underneathprotrusions10, and the user's grip on the tool is maintained by contact between the user's hand and the high friction material of theflexible sheet8. It can therefore be seen that by suitable choice of material of theflexible sheet8, the frictional properties of thesheet8 can be optimized, while the vibration damping properties of the gel-filledblister packs20,120,220 are generally superior to the vibration damping properties of known high friction materials or air filled cushions used in conventional handle assemblies.
• Referring toFIGS. 4A to4D, handle404 ofpower tool401 of a second embodiment of the invention, for example, a drill, is defined by two halves402A,402B ofhousing402.Drill401 includes anupper motor housing430 disposed abovehandle404.Housing430 may extend along or at a small angle to the horizontal direction, whilehandle404 may extend along or at a small angle to the vertical direction. As shown, bothhousing430 and handle404 are slightly angled to the horizontal and vertical directions when the drill rests on a horizontal surface. The lower surface ofmotor housing430 transitions intohandle404 atfillet404a. At its lower end handle404 transitions intobattery receiving portion435 at asecond fillet404b.Battery440 is slidably received in the receiving portion. Although the drill shown is a cordless drill receiving a removable battery which when inserted in the receiving portion forms the lower end of the drill, the invention could also be directed to a corded drill as well in which there is not a substantial part of the drill housing which is removable.
• Threegel pieces422a-cprotrude from the rear ofhandle404 and extend throughcover plate411, which may be formed in one or two pieces. Bothgel pieces422a-candcover plate411 may have the same structure as the cover plate and gel pieces described with respect to the embodiment ofFIGS. 1-3.Gel pieces422a-cencompass the rear ofhandle404 and extend partially around both sides ofhandle404 and preferably terminate rearwardly of the center axis Y-Y ofhandle404, which extends at a slight angle to the vertical. Preferably,upper gel piece422ais positioned relatively high onhandle404, encompassingupper fillet404a, oppositedepressible trigger429 which is disposed through the front ofhandle404.Upper gel piece422aextends downwardly for substantially the same distance astrigger429 to provide the maximum cushioning benefit when the user actuatestrigger429.
• In a preferred embodiment, the overall gripping region of the tool extends generally fromupper fillet404atowardslower fillet404bin a range of 80-100 mm as measured in the vertical direction. Preferablylower gel piece422cterminates above and adjacentlower fillet404b.Upper gel piece422amay extend in the vertical direction ofhandle404 for 36 mm. At its maximum,upper gel piece422aextends along each side ofhandle404 in the direction which is transverse to the centerline Y-Y to a location which is 11 mm rearward of centerline Y-Y. The distance in the vertical direction betweenupper gel piece422aandmiddle gel piece422bmay be 8 mm. The dimension of the middle andlower gel pieces422band422cin the vertical direction may be 15 mm, and each may extend along each side ofhandle404 in the direction which is transverse to the centerline Y-Y to a location which is 13 mm rearward of the centerline Y-Y. The distance in the vertical direction betweenmiddle gel piece422bandlower gel piece422cmay be 7 mm. The distance in the vertical direction betweenlower gel piece422candlower fillet404bmay be 15 mm. The thickness ofgel pieces422a-cmay be between 5-10 mm.
• Cover plate411 may be formed as one saddle-shaped piece which extends about the rear and partially along each side ofhandle404. Alternatively coverplate411 may be formed as two pieces, with one piece disposed on each handle half. As measured in the vertical direction,cover plate411 may extend from a location which is 6 mm aboveupper gel piece422ato a location which is 8 mm belowlower gel piece422c. The openings incover plate411 have dimensions corresponding to those ofgel pieces422a-c. As shown, at an upperlocation cover plate411 may extend forwardly of centerline Y-Y for 12 mm at its maximum. At a location which is about 32 mm below the upper edge ofcover plate411,cover plate411 narrows such that it only extends to a location which is 4 mm to the rear of centerline Y-Y. As shown inFIG. 4D,gel piece422cmay project outwardly fromcover plate411 by 3 mm.Gel pieces422aand422balso project outwardly fromcover plate411 by 3 mm.
• FIG. 4E shows an alternative to the embodiment shown inFIGS. 4A-4D. InFIG. 4E, only asingle gel piece422′ is disposed onhandle404′.Gel piece422′ may have a saddle shape and wrap around the rear ofhandle404′, and extend forwardly on both side ofhandle404′, terminating to the rear of centerline Y-Y. Alternatively, twogel pieces422′ which jointly form a saddle shape and wrap around the rear ofhandle404′ may be used. With respect to the portion ofhandle404,404′ covered by the gel piece(s), the overall dimensions ofgel piece422′ are similar to those of the threegel pieces422a-cof FIGS.4A-C. However, in the present embodiment,gel piece422′ also occupies the regions ofhandle404′ between each of gel pieces.422a-c. Similarly, the overall dimensions ofcover plate411′ is similar to the overall dimensions ofcover plate411.
• It will be appreciated skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims.

Claims (16)

1. A drill comprising:

a motor housing;

a handle extending downwardly from said motor housing, said handle having a front surface, a rear surface and side surfaces, said handle comprising a gripping portion;

a chamber enclosing a gel material disposed on said handle, said chamber disposed about the rear surface of said handle and extending forwardly along both said side surfaces, said chamber extending outwardly from said gripping portion.

2. The drill recited inclaim 1 further comprising a trigger switch extending through said front surface, said chamber disposed on said handle at a location opposite said trigger switch.

3. The drill recited inclaim 1, an upper transition defined between said motor housing and said handle, said chamber disposed so as to encompass said transition.

4. The drill recited inclaim 3, said drill comprising a lower housing structure disposed below said handle, a lower transition defined between said handle and said lower housing structure, said chamber terminating at a location adjacent said lower transition.

5. The drill recited inclaim 4, said lower housing structure comprising a battery receiving housing.

6. The drill recited inclaim 1, said handle having a longitudinal center axis, said chamber extending along said side surfaces so as to terminate rearwardly of said center axis.

7. The drill recited inclaim 6 further comprising a trigger switch extending through said front surface, said chamber disposed on said handle at a location opposite said trigger switch.

8. The drill recited inclaim 7, an upper transition defined between said motor housing and said handle, said chamber disposed so as to encompass said transition.

9. The drill recited inclaim 6, an upper transition defined between said motor housing and said handle, said chamber disposed so as to encompass said transition.

10. A drill comprising:

a motor housing;

a handle extending downwardly from said motor housing, said handle having a front surface, a rear surface and side surfaces;

a lower housing structure disposed below said handle;

an upper transition defined between said motor housing and said handle;

a lower transition defined between said handle and said lower housing structure; and

first and second chambers enclosing a gel material disposed on said handle, said chambers disposed about the rear surface of said handle and extending forwardly along both said side surfaces, said chambers displaced from each other in the longitudinal dimension of the handle and jointly covering a portion of the rear surface of the handle defined between the upper transition and the lower transition.

11. The drill recited inclaim 10, the portion comprising a majority of the rear surface of the handle defined between the upper transition and the lower transition.

12. The drill recited inclaim 11 further comprising a third chamber enclosing a gel material disposed on said handle, said first, second and third chambers displaced from each other in the longitudinal dimension of the handle and jointly covering a majority of the rear surface of the handle defined between the upper transition and the lower transition.

13. The drill recited inclaim 11, one of said chambers disposed so as to encompass said upper transition.

14. The drill recited inclaim 13, said lower housing structure comprising a battery receiving housing.

15. The drill recited inclaim 10, further comprising a cover plate made of a material which is relatively hard as compared to said chambers, said cover plate disposed on said handle and including an aperture through which said chambers protrude.

16. A drill comprising:

a motor housing;

a handle extending downwardly from said motor housing, said handle having a front surface, a rear surface and side surfaces;

a chamber enclosing a gel material disposed on said handle, said chamber disposed about the rear surface of said handle and extending forwardly along both said side surfaces;

and a cover plate made of a material which is relatively hard as compared to said chamber, said cover plate disposed on said handle and including an aperture through which said chamber protrudes.

Images