# Patent

## Title
Modular power tool

## Abstract

A modular power tool incorporates a modular drive system and modular handle set that is reversible for use with both a left hand and right hand configuration. The modular drive system and handle set of the modular power tool of this invention reduces the need for derivative circular saw designs by introducing common components.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser. No. 10/517,034, filed Dec. 7, 2004 which is a National Phase of PCT/US03/17703, filed Jun. 5, 2003 which is a continuation of Ser. No. 10/165,167, filed on Jun. 7, 2002, now U.S. Pat. No. 6,898,854, the disclosures of which is incorporated herein by reference.


FIELD OF THE INVENTION
The present invention relates generally to a modular power tool. In particular, the present invention relates to a modular circular saw wherein the handle supports the drive assembly and is adaptable to be fastened on either side of the saw blade, providing a right hand and left hand assembly.
BACKGROUND OF THE INVENTION
Circular saws are known in the art. A growth in circular saw applications has created many derivative circular saw designs for each specific type of use. Many of these applications require changes to motor platforms, blade guarding and gear cases. Specifically, most circular saw designs do not allow different motor sizes to fit the same housing. This requires a housing redesign and a new transmission for each different or new motor size. The transmission or gear case is typically the most complex component to develop and dimensionally qualify because it has the most stringent tolerances and becomes the foundation for all the other structure that is mounted to it. Hence, the product development time for a derivative circular saw is extensive and somewhat prohibitive.
In addition, there is a need for a left and right hand blade applications with respect to the handle set for many circular saw designs, which usually requires a handle set redesign. The design of the handle set is complicated because generally battery applications or power sources fit onto the handle set. Thus, development of a new handle set for each circular saw product creates a tremendous amount of design resources, tooling cost and development time.
Accordingly, a need exists for a modular power tool for a circular saw application having the ability to incorporate numerous gear cases, motor platforms and guard designs, with a handle operable in both a left hand and right hand configuration.
SUMMARY OF THE INVENTION
The present invention provides a modular power tool for a circular saw application. The modular power tool incorporates a modular drive system that employs a mounting flange portion with a common hole pattern for coupling motors of various sizes to a universal gear case. The handle set of the modular power tool is designed with a cavity through which the drive system passes. The handle set further includes a universal mating portion for receipt of a variety of battery and power sources. The handle set is also reversible for use with both a left hand and right hand configuration. The modular drive system and handle set of the modular power tool of this invention reduces the need for derivative circular saw designs by introducing common components.



BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
FIG. 1 is an exploded perspective view of a modular power tool in a left hand orientation according to the principles of the present invention;
FIG. 2 is an exploded view of the modular power tool in a right hand orientation;
FIG. 3 is a side view of a handle set according to the principles of the present invention;
FIG. 4 is a front view of a gear case according to the principles of the present invention;
FIG. 5 is a perspective view of the modular circular saw in a left hand configuration;
FIG. 6 is a perspective view of the right hand configuration of the modular circular saw according to the principles of the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring generally to FIGS. 1 and 2, an exploded view of a first embodiment of a modular power tool 10 is shown. The present invention is directed towards a circular saw, however, it is to be understood that the principles embodied herein are equally applicable to other types of power tools as well.
The modular power tool or power circular saw 10 includes a reversible clam shell handle set 12 with a symmetrical motor housing 14. A universal drive train platform is provided with a motor case 18 which has a flange 20 and mounting hole pattern which is designed for the largest motor, such that smaller motors can be provided with the same flange and hole pattern. The universal drive train platform also includes a universal gear case 22. Various guards 24 and shoe assemblies 26 can be provided for a specific saw application such as right and left hand blade applications, wood or metal cutting, etc. Fasteners 28 extend through mounting holes 30, provided in the symmetrical motor housing 14, holes 32, provided in the reversible clam shell handle set 12, holes 34, provided in the flange 20 of the motor case 18, mounting holes 36, provided in the universal gear case 22 and finally into mounting holes 38 provided in guard 24.
The symmetrical motor housing 14 can be made out of one or two pieces. The symmetrical motor housing 14 is generally made from plastic and encloses an end of the motor case 18. Different size symmetrical motor housings 14 can be optionally used to reduce the size of the assembly for different motor sizes. This reduces the cost and development time required of an entire new housing tool. The symmetrical motor housing 14 is coupled to the two-piece clam shell handle set 12.
The two-piece clam shell handle set 12 incorporates an identical and symmetrical mounting pattern on both sides of each clam shell portion 12a, 12b. This clam shell handle set 12 has an opening 40 that allows the entire range of desired motor cases 18 to pass through it for mounting onto the universal gear case 22. The clam shell handle set 12 also supports the motor case 18 for coupling to the symmetrical motor housing 14. In addition, clam shell handle set 12 has an open end cavity 42 (best shown in FIG. 2) designed so that different mold inserts can be used for different battery and power sources to be connected to the power circular saw 10. Clam shell handle set 12 further includes a trigger 44 and a safety 46 (best shown in FIG. 3). Both trigger 44 and safety 46 are generally made from plastic. Safety 46 extends through the clam shell handle set 12, and must be held for the trigger 44 to release.
The modular universal transmission and gear case 22 is symmetrical and has the ability to incorporate numerous gear ratios, motor platforms and guard designs. In addition, as shown in FIG. 4, the universal gear case 22 has symmetrical air flow vents 39 with fins and ribbing 48 that can direct air to remove dust and debris from a cutting line in both right and left handed blade applications.
Referring generally to FIGS. 1 and 2, the assembly of power circular saw 10 generally involves inserting motor case 18 through the cavity 40 of the clam shell handle set 12. The motor case 18 has a flange 20 with holes 34 which couple the universal gear case 22 to the motor case 18. The universal gear case 22 is further coupled to the guard and shoe assembly 24, 26. Symmetrical motor housing 14 is fixed to the end of the clam shell handle set 12 such that it covers the rest of the motor case 18. The symmetrical motor housing 14 provides the starting point for the fasteners 28, specifically fasteners 28 are threaded though the symmetrical motor housing 14 via holes 30 into the clam shell handle set 12 via holes 32, through motor assembly holes 34, the gear case holes 36 and into the guard 24. The battery 50 (FIGS. 5 and 6) or other power source are mounted onto cavity 42. The left hand assembly for the power circular saw 10 is shown FIG. 5. The right hand assembly for the power circular saw 10 is shown in FIG. 6 and is achieved by reversing the orientation of the clam shell handle set 12.
The design of the present invention allows the clam shell handle set 12 to be mounted either to the left or to the right of the blade and gear case. Features that allow this arrangement include the identical and symmetrical mounting fasteners on both sides of each handle clam shell. In addition, the handle set defines an opening that is large enough for the entire range of different sized motor assemblies to pass through it. Furthermore, the motor housing and gear case are symmetrically designed for left hand and right hand use. The blade guard and shoe can be changed for different uses and for left or right hand orientations.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

## Claims

1. A modular power tool comprising:
a motor;
a motor housing defining a chamber for said motor;
a handle defining a through cavity;
a gear case coupled to said motor;
a guard assembly coupled to said gear case; and
wherein, said handle and said gear case are adaptable for use in a left and a right hand orientation such that in said left hand orientation, said gear case is mounted on a first side of said handle and includes a first end located on said first side and, in said right hand orientation, said gear case is mounted on a second side of said handle opposite said first side and said first end is located on said second side.

2. The modular power tool of claim 1 wherein said guard assembly includes a guard and a shoe assembly coupled to said guard.

3. The modular power tool of claim 1 wherein said gear case includes a pair of substantially symmetrical air flow passages each of which provides a vent passage in the respective left and right hand orientation.

4. The modular power tool of claim 3 wherein said air flow passages have substantially symmetrical fins and ribbing.

5. The modular power tool of claim 1 wherein said handle is a clam shell handle.

6. The modular power tool of claim 3 wherein said handle is adaptable to receive a power supply.

7. The modular power tool of claim 1 wherein said first side of said handle is configured to accept one of said motor and said motor housing and said second side of said handle is configured to accept the other of said motor and said motor housing.

8. The modular power tool of claim 1 wherein said motor further includes a flange for coupling to said handle.

9. The modular power tool of claim 1 wherein said motor housing further includes a flange for coupling to said handle.

10. The modular power tool of claim 1 wherein said motor housing is symmetrical.

11. The modular power tool of claim 1 wherein said motor, said gear case, said handle, said guard assembly and said housing are connected by a plurality of common fasteners.

12. The modular power tool of claim 1, wherein said second side is symmetrically opposite said first side.

13. The modular power tool of claim 1, wherein said first end of said gear case is offset from said second side of said handle toward said first side of said handle when in said left hand orientation and said first end of said gear case is offset from said first side of said handle toward said second side of said handle when in said right hand orientation.

14. The modular power tool of claim 1, wherein said first side of said handle defines a first outer surface of said handle and said second side of said handle defines a second outer surface of said handle.