Tool driving or impacting – Means to drive tool about an axis – Electric motor
Reexamination Certificate
1998-08-25
2001-07-24
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Means to drive tool about an axis
Electric motor
C173S029000, C173S170000, C173S171000
Reexamination Certificate
active
06263980
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power tool and has particular although not exclusive, relevance to battery powered tools.
2. Description of the Related Art
It is conventional for power tools to be designed and built for a dedicated purpose, such as a drill, a jigsaw or a sander. If the user needs to undertake a sanding operation he will use a dedicated sander. If then he needs to drill a hole in a workpiece he will swap the sander for a dedicated drill, and so on.
Whilst such swapping over of dedicated tools is not inconvenient, it does mean that, particularly for the person who needs to use power tools relatively infrequently, considerable expense is incurred in acquiring a broad range of these dedicated power tools.
Furthermore, in the case of so-called “cordless” or battery-powered tools, the user will either need to change the battery pack when changing dedicated tools, or have several ready-charged batteries available for use. These alternative options are cumbersome or expensive respectively.
Solutions to the above problems have been proposed in the past and one such solution entails providing a power tool including a motorised drive which is capable of accepting any one of a plurality of discrete attachments which achieve a dedicated purpose. This means that rather than purchasing a dedicated entire power tool for each job, the user only has to purchase a dedicated attachment (which is cheaper than a dedicated entire tool) and just swap these over as and when necessary.
There still exist certain problems with such solutions, however. In a system such as the discreet attachments described above, it is important to achieve a high degree of alignment between the body of the tool providing the drive and the attachment which receives the drive. In the case of a rotational drive such as a drive shaft, a high degree of axial alignment between the driving and driven shafts is imperative in order to achieve an efficient transfer of energy between the two and also to avoid creating unnecessary mechanical wearing at the interface between the shafts.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to at least alleviate the aforementioned shortcomings by providing a power tool including a body portion defining a handle and a motor mounted within the body portion, which motor is arranged to drive an output spindle of the tool; the body portion further defining an opening around the output spindle, which opening accepts any one of a plurality of attachment members presented thereto, the power tool characterised in that the motor is mounted within the housing by aplurality of supports spaced along the axial length of the motor and wherein at least one of the supports of the plurality does not rigidly contact the motor, thereby to permit the motor to move within its mounting. Thus, by enabling the motor of the body portion of the tool to move, a high degree of axial and positional alignment between the output spindle of the motor and the rotational drive of the attachment may be achieved because this degree of movement permits of automatic co-axial alignment between the two parts.
Preferably at one end of the axial length of the motor a plurality of supports make rigid contact therewith and at the other end of the axial length of the motor at least one of the supports of the plurality do not rigidly contact the motor thereby allowing themotor to pivot about the point at which it is in rigid contact with the said supports. By provision of pivoting movement of the motor, the amount of movement, or “play” exhibited by the motor may be limited and have any unnecessary movement avoided. Additionally or alternatively the motor, at either end of its axial length, is formed in circular cross-section and the supports of the plurality are found therearound. This shape permits a method of construction of the power tool which is relatively easy to assemble.
In a preferred embodiment the plurality of supports is formed from, or integrally with, the body portion itself.
Also the body portion may be formed in two halves which two halves come together and thereby encapsulate the motor therewithin.
Furthermore movement of the motor within the housing, relative to an attachment member, when presented to the tool, is prevented. Also the motor may itself, be connected to the output spindle.
REFERENCES:
patent: 3772542 (1973-11-01), Hallerback
patent: 4081704 (1978-03-01), Vassos et al.
patent: 4597453 (1986-07-01), Kilmer et al.
patent: 5033552 (1991-07-01), Hu
patent: 5170851 (1992-12-01), Kress et al.
patent: 5394039 (1995-02-01), Suchdev et al.
patent: 5624000 (1997-04-01), Miller
patent: 19 02 315 (1964-10-01), None
patent: 2 288 588 (1995-10-01), None
Black & Decker Inc.
Shapiro Bruce S.
Smith Scott A.
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