EP1238761A1

EP1238761A1 - Balanced Rotary power tool

Info

Publication number: EP1238761A1
Application number: EP01115972A
Authority: EP
Inventors: Robert L. Hartman; Steven C. Carney; Isidro M. Alanis
Original assignee: Snap On Technologies Inc
Current assignee: Snap On Inc
Priority date: 2001-03-07
Filing date: 2001-06-29
Publication date: 2002-09-11
Also published as: TWM248576U; JP2002264042A; CN100346936C; CN1373027A

Abstract

A hand-held rotary power tool (10) includes a housing (11) with a top portion (12), a handle portion (13), and a bottom portion (14) arranged into a relatively T-shaped configuration. A motor (22) is located within the bottom portion (14) of the housing (11). An input shaft (21) extends from the motor (22) through the handle portion (13) and rotatively couples the motor (22) to a gear box (20) located in the top portion (12) of the housing (11). An output shaft (24) extends forwardly from the gear box (20) at an angle that is substantially perpendicular to the longitudinal axis of the input shaft (21), and is coupled to a chuck (15) for rotation thereof. The tool (10) is balanced to inhibit rotation in the plane of the input and output shafts (21,24), in use.

Description

Background

This application relates generally to a rotary power tool. More particularly, this application relates to a hand-held rotary power tool with balanced weight distribution, and with tight access capability.

Hand-held rotary power tools are common, with predominantly two types of such tools available on the market, the pistol grip rotary tool and the right angle rotary tool. The two types of tool differ largely with respect to their general orientation. The standard pistol grip rotary tool has a motor, a gear box, and an output shaft all horizontally aligned within a housing and a handle depending from the rear of the housing. Right angle rotary tools are more vertically orientated in order to be used in confined spaces. The right angle rotary tools have a motor and a gear box vertically aligned within a handle, and an output shaft extending horizontally from the gear box.

One of the disadvantages of the pistol grip rotary tools is that they are relatively unbalanced. Most of these drills are heavily front loaded with the typically heaviest components of a rotary tool, the gear box and the motor, positioned forwardly of the handle. This creates a rotational torque on the handle located at the back of the drill. The hand must first overcome this rotational torque in order to accurately use the tool. The effort exerted to counterbalance the rotational torque created by the front end loading fatigues the user's hand and may cause inaccuracies in the use of the tool.

Right angle rotary tools are typically used for applications where the work space does not allow the use of a pistol grip rotary tool. The main drawback with these tools is that they are often difficult to work with. This is because the motor is typically positioned within the handle portion of the tool forcing the handle to be wider than is ergonomically desirable for comfortable gripping by a user's hand. As a whole, right angle rotary tools are typically less ergonomically friendly then the pistol grip rotary tool, and as such, they are typically used only as a specialty tool.

Summary

Therefore, it is a general object of this application to provide a hand-held rotary power tool that avoids the disadvantages of prior designs while affording additional structural and operating advantages.

An important feature is the provision of a hand-held rotary power tool which is relatively balanced, thereby minimizing rotational torque on the handle.

Another important feature is the provision of a hand-held rotary power tool with tight access capabilities.

Another important feature is the provision of a hand-held rotary power tool which is ergonomically designed for comfortable gripping by a user's hand.

Brief Description of the Drawings

For purposes of facilitating an understanding the subject matter sought to be protected, there is illustrated in the accompanying drawings an embodiment thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appropriated.

FIG. 1 is a perspective view of an embodiment of the rotary power tool.

FIG. 2 is a side elevational view of the rotary power tool in FIG. 1, with the housing removed in order to show further detail.

FIG. 3 is a reduced side elevational view of the rotary power tool, of FIG. 1.

Detailed Description

Referring to FIG. 1, an embodiment of a handheld rotary power tool 10 is includes a housing 11 with a top portion 12, a handle portion 13, and a bottom portion 14 arranged into a relatively T-shaped configuration. The handle portion 13 and the bottom portion 14 extend longitudinally below the top portion 12, with the handle portion 13 positioned between the top portion 12 and bottom portion 14. The handle portion 13 including an ergonomic grip section 19 with contoured surfaces adapted for placement of a user's hand therearound.

A chuck 15 extends forwardly from the top portion 12 with jaws 16 for attachment with a tool bit. A trigger 17 extends forwardly from the handle portion 13 for controlling the operation of a motor. A reversing shuttle 18 extends intermediate to the top portion 12 and the handle portion 13 for controlling the rotational direction of the motor.

Referring to FIG. 2, a motor 22 is located within the bottom portion 14 of the housing11. An input shaft 21 is rotatively coupled to the motor 22, and extends from the motor 22 through the handle portion 13, eventually rotatively coupling to a gear box 20 located in the top portion 12 of the housing 11.

An output shaft 24 is also rotatively coupled to the gear box 20, the output shaft 24 extending therefrom at an angle that is substantially perpendicular to the longitudinal axis of the input shaft 21. The output shaft 24 extends from the top portion 12 of the housing 11, and is coupled to the chuck 15 for rotation thereof.

A switch assembly 23 is coupled to the trigger 17 and is electrically connected in circuit with the motor 22 for activation thereof. The switch assembly 23 is located along an upper portion of the handle portion 13. The reversing shuttle 18 lies just above the switch assembly 23 intermediate to the top portion 12 and the handle portion 13. The directional shuttle 18 is also coupled to the motor in a known manner, controlling the rotational direction thereof. A power cord 25 is located along the bottom portion 14 and is also conductively coupled to the motor 22, providing power thereto.

Referring to FIGS. 2 and 3, the rotary power tool 10 is designed for optimum single-hand operation. The length of the input shaft 21 allows for the motor 22 to be located below the handle portion 13, allowing the handle portionl3 to be appropriately and ergonomically designed thin enough so as to be comfortably gripped by the hand of a user. The handle portion 13 can include an ergonomically designed grip section 19 designed to allow for secure and comfortable positioning of a hand relative to the drill. The grip section 19 has contoured surfaces which conform to the palm surfaces of a hand. The handle portion 13 may also be angled slightly at roughly 15° angle with respect to an axis defined by the input shaft 21, in order to comfortably accommodate the natural angle of the hand as it is applied to the drill. Also, the trigger 17 and the directional shuttle 18 are positioned to enable relatively easy finger tip access to the hand gripping the grip section 19.

Adding to the optimal single hand design of the rotary power tool 10 is the relative balance of the device. The T-shaped configuration of the housing enables the weight of the tool to be effectively distributed to minimize weight-induced rotational torque on the handle. The configuration of the housing 11 enables the heaviest components in the rotary tool 10, namely the gear box 20 and the motor 22, to be substantially vertically aligned in use, minimizing rotational torque. Furthermore, the positioning of the motor 22 below the handle portion 13 further reduces rotational torque by providing a counterbalance to the chuck 15. Any rotational torque produced by the weight of the components in the top portion 12 of the housing 11 forward of the shaft 21, will be opposed by the weight of the components located in the bottom portion 14 of the housing 11.

An additional benefit of the design of the rotary tool is that the positioning of the motor 22 below the handle portion 13, minimizes the length of the top portion 12, providing tight access capabilities.

The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While a particular embodiment has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants' contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.

Claims

A balanced rotary tool comprising:

a generally T-shaped housing including a top portion having front and rear ends, a handle portion joined to the top portion between the front and rear ends and a bottom portion depending from the handle portion;

a motor located within the bottom portion;

a gear box located within the top portion;

an input shaft rotatively coupling the motor to the gear box; and

an output shaft rotatively coupled to the gear box and extending therefrom at an angle substantially perpendicular to the input shaft.
The rotary tool of claim 1, wherein the handle portion includes a grip area that is inclined at an angle of approximately 15 degrees in relation to an axis defined by the input shaft.
The rotary tool of claim 1, and further comprising a trigger mechanism disposed between the grip area and the top portion.
The rotary tool of claim 1, and further comprising a slidable directional control mechanism positioned for access by a user's hand grasping the handle section.
The rotary tool of claim 1, wherein the handle defines an axis passing through the gear box forwardly of the input shaft.
The rotary tool of claim 1, and further comprising a power cord conductively coupled to the motor.
The rotary tool of claim 1 wherein the handle portion includes an ergonomically shaped grip area.
A balanced rotary tool comprising:

a housing including a top portion having front and rear ends, a handle portion joined to the top portion between the front and rear ends and including an ergonomic grip area, and a bottom portion depending from the handle portion;

a motor located within the bottom portion;

a power cord conductively coupled to the drive motor and extending through the bottom portion;

a gear box located within the top portion;

an input shaft rotatively coupling the drive motor to the gear box; and

an output spindle rotatively coupled to the gear box and extending therefrom at an angle substantially perpendicular to the input shaft.
The rotary tool of claim 8 wherein the housing is generally T-shaped.