US20060060366A1 - Variable speed drill - Google Patents

Abstract

A variable speed drill includes a housing and a motor within the housing. The motor has (a) a motor field lamination diameter greater than 65 mm, (b) a motor current rating greater than 8 amps, (c) a motor power level greater than 600 Watts, (d) a maximum torque level at the chuck greater than 580 in-lbs, (e) a weight greater than 5.5 pounds or (f) a maximum speed less than 550 rpm. A mixing implement is rotationally coupled to the motor. A variable speed switch is mounted to the housing and is operable to vary a rotational speed of the motor and therefore of the mixing implement.

Description

FIELD OF THE INVENTION
• The present invention relates to power tools and more particularly to a variable speed drill.
BACKGROUND OF THE INVENTION
• In many workplaces or construction site environments, it is necessary to use various substances to perform a given task. Many of these substances, for example paints, coatings, mortars, cements, powders, etc., may require a certain amount of mixing before use. As the quantity of these substances can be relatively high in any given application, a need arose for an easy and efficient way to mix these substances.
• To meet this need, various mixing implements or “paddles” have been introduced into the market. These paddles are designed to be coupled to traditional drills commonly found in many workplaces and construction sites. In this regard, operation of the drill in turn rotates the paddle which may then mix a given substance.
• However, there are limitations in the art. For example, to successfully mix a thick substance such as cement or mortar, a power drill having a high torque must be employed. These drills do not have variable speed switches to regulate the rotational speed of the paddle, and therefore the drills must be turned on and off in order to reduce the rotational speed and hence splashing or over-mixing. This can be tiring to the user and is inefficient. Accordingly, the present invention seeks to improve the art with a variable speed drill for use in mixing applications.
SUMMARY OF THE INVENTION
• A variable speed drill includes a housing and a motor within the housing. The motor has a lamination length of at least 30 millimeters and a lamination diameter of at least 73 millimeters. A mixing implement is rotationally coupled to the motor. A variable speed switch is mounted to the housing and is operable to vary a rotational speed of the motor and therefore of the mixing implement.
• Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
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 a front perspective view of a variable speed drill constructed according to the principles of the present invention having an exemplary mixing implement attached thereto;
• FIG. 1A is a front perspective view of an alternate mixing implement used with the variable speed drill of the present invention;
• FIG. 2A is a perspective view of a motor used with the variable speed drill of the present invention;
• FIG. 2B is a side view of a motor used with the variable speed drill of the present invention;
• FIG. 2C is a front view of a motor used with the variable speed drill of the present invention;
• FIG. 3 is a schematic connection diagram of the variable speed drill of the present invention; and
• FIG. 4 is a graph illustrating the function of the variable speed switch 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.
• With reference toFIG. 1, a variable speed drill constructed according to the principles of the present invention is generally indicated byreference numeral10. Thevariable speed drill10 generally includes ahousing12 that partially defines ahandle14. Thehousing12 encases amotor16 including an armature16A and field winding16B (FIGS. 2A-2C) that are operable to rotate achuck18. In the particular example provided, themotor16 receives power from a power source (not shown) through acord19 coupled to thehandle14 of thevariable speed drill10.
• Thechuck18 is adapted to receive an implement (e.g., a tool such as a drill bit, screwdriver head, etc.) therein. In the particular example provided, thechuck18 receives a mixing implement or “paddle”20. Rotation of thechuck18 upon activation of the motor (FIG. 2) in turn rotates thepaddle20. Thepaddle20 is adapted to be used in mixing a particular substance via rotation of thepaddle20. For example, paint, mortar, cement, or plasters may be mixed by thepaddle20. Moreover, various other paddle designs may be used to mix these substances. With brief reference toFIG. 1A, analternate paddle20′ is illustrated. Thepaddle20′ is adapted to be coupled to thechuck18 of thevariable speed drill10. Thepaddle20′ is best used with powder materials and paints.
• Returning toFIG. 1, thevariable speed drill10 is operated by activating atrigger22. Thetrigger22 is mounted within thehandle portion14 of thehousing12. Thetrigger22 is coupled to themotor16, shown inFIGS. 2A-2C, and when depressed activates the motor. Thetrigger22 engages avariable speed switch24 which is mounted within thehandle portion14 of thehousing12. Thevariable speed switch24 is operable to variably control the power output of themotor16 and accordingly operable to variably control the rotational speed of thechuck18 and in turn thepaddle20.
• With reference toFIGS. 2A-2C, the motor is an electric motor having anoutput shaft26 extending from the armature16A. Theoutput shaft26 is coupled to the chuck18 (FIG. 1) through a gear reduction system, which will increase the torque atchuck18. Themotor16 is preferably a “heavy-duty,” electric motor. In other words, themotor16 has a high current rating, greater than 8 amps, preferably 9 amps, a high power level, greater than 600 Watts, preferably 640 Watts, and the motor has a large size with a field lamination diameter (D) (FIG. 2C) of at least 65 mm, preferably 73 mm, and a field and armature lamination stack length (L) (FIG. 2B) of at least 30 mm. A motor of the above size provides 10-12 in-lbs of torque, which is typically necessary for heavy-duty mixing, and with agear reduction mechanism30 having a gear reduction of approximately 1 to 40 is capable of providing a maximum torque at the chuck which is greater than 580 in-lbs, preferably 595 in-lbs. It should be appreciated, however, that various other sized motors may be employed with the present invention. Thedrill10 has a larger, heavier construction than previous variable speed drills, including a weight greater than 5.5 pounds, preferably 7.5 pounds or greater 9
• Turning now toFIG. 3, an electronic diagram of thevariable speed switch24 and themotor16 is generally indicated byreference numeral100. The electronic diagram100 illustrates how the power from thecord19 is transferred to the field windings16B of the motor. In the example provided, thevariable speed switch24 includes avariable power module102 located therein. Thevariable power module102 is connected between a power source via thecord19 and themotor16.
• During operation of thevariable speed drill10, power received from thecord19 is communicated through thevariable power module102. By moving theswitch24 into various positions, theswitch24 in turn sets thevariable power module102 to provide variable power flow into themotor16 to achieve variable speeds. Accordingly, the rotational output of themotor16 and hence the rotational speed of thepaddle20 may then be governed by simply setting the position of thevariable speed switch24. The graph ofFIG. 4 shows plot of trigger travel vs. output voltage and shows that the output voltage ranges between a low power position A and a “full power” position B with the trigger travel. Thedrill10 preferably has a maximum speed less than 550 RPM. In the “low power” position, only a fraction of the power supplied from thecord19 is transferred to themotor16. In the “full power” position, full power is supplied from thecord19 to themotor16. It should be appreciated that any number of switch positions may be employed with the present invention to provide a range of rotational speeds to thepaddle20. Variable output power modules of this type are known.
• By allowing a user to set the rotational speed of thepaddle20 via thevariable speed switch24, thevariable speed drill10 is ideal for mixing various substances. By providing various rotational speeds for thepaddle20, the mixing can be tailored to the substance to be mixed, thereby reducing the chance of splatter, over-mixing, or under-mixing. Variable speed drills having a smaller motor than the present invention have been known. However, these known variable speed drills have insufficient power to use for typical heavy-duty mixing applications. Previous heavy-duty drills that are used for heavy-duty mixing applications have to be repeatedly started and stopped until the material being mixed reaches a consistency that allows constant running of the motor. Thus, the use of a heavy-duty motor on a variable speed drill for heavy-duty mixing applications is believed to be a novel and non-obvious improvement in the art. Heretofore, variable speed drills having: (a) a motor field lamination diameter greater than 65 mm, (b) a motor current rating greater than 8 amps, (c) a motor power level greater than 600 Watts, (d) a maximum torque level at the chuck greater than 580 in-lbs, (e) a weight greater than 5.5 pounds or (f) a maximum speed less than 550 rpm, have not existed.
• 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 (27)

1. A variable speed drill comprising:

a housing;

a motor within the housing having a lamination length of at least 30 millimeters and a lamination diameter of at least 65 millimeters;

a variable speed switch mounted to the housing and operable to vary a power output of the motor.

2. The variable speed drill ofclaim 1, wherein the housing defines a handle, and the variable speed switch is mounted to the handle.

3. The variable speed drill ofclaim 1, wherein the variable speed switch is operable in a first position and a second position.

4. The variable speed drill ofclaim 3, wherein movement of the variable speed switch from the first position to the second position increases the power output of the motor.

5. The variable speed drill ofclaim 1, further comprising a mixing implement rotationally coupled to the motor.

7. A variable speed drill comprising:

a housing;

a motor within the housing having a motor current rating greater than 8 amps;

a variable speed switch mounted to the housing and operable to vary a power output of the motor.

8. The variable speed drill ofclaim 7, wherein the housing defines a handle, and the variable speed switch is mounted to the handle.

9. The variable speed drill ofclaim 7, wherein the variable speed switch is operable in a first position and a second position.

10. The variable speed drill ofclaim 9, wherein movement of the variable speed switch from the first position to the second position increases the power output of the motor.

11. The variable speed drill ofclaim 7, further comprising a mixing implement rotationally coupled to the motor.

12. A variable speed drill comprising:

a housing;

a motor within the housing having a motor power level greater than 600 Watts;

a variable speed switch mounted to the housing and operable to vary a power output of the motor.

13. The variable speed drill ofclaim 12, wherein the housing defines a handle, and the variable speed switch is mounted to the handle.

14. The variable speed drill ofclaim 12, wherein the variable speed switch is operable in a first position and a second position.

15. The variable speed drill ofclaim 14, wherein movement of the variable speed switch from the first position to the second position increases the power output of the motor.

16. The variable speed drill ofclaim 12, further comprising a mixing implement rotationally coupled to the motor.

17. A variable speed drill comprising:

a housing;

a motor within the housing having a maximum speed less than 550 rpm;

a variable speed switch mounted to the housing and operable to vary a power output of the motor.

18. The variable speed drill ofclaim 17, wherein the housing defines a handle, and the variable speed switch is mounted to the handle.

19. The variable speed drill ofclaim 17, wherein the variable speed switch is operable in a first position and a second position.

20. The variable speed drill ofclaim 19, wherein movement of the variable speed switch from the first position to the second position increases the power output of the motor.

21. The variable speed drill ofclaim 17, further comprising a mixing implement rotationally coupled to the motor.

22. A variable speed drill comprising:

a housing;

a motor within the housing;

a gear reduction mechanism drivingly connected to said motor;

a chuck drivingly connected to said gear reduction mechanism, wherein said drill has a maximum torque level at the chuck greater than 580 in-lbs; and

a variable speed switch mounted to the housing and operable to vary a power output of the motor.

23. The variable speed drill ofclaim 22, wherein the housing defines a handle, and the variable speed switch is mounted to the handle.

24. The variable speed drill ofclaim 22, wherein the variable speed switch is operable in a first position and a second position.

25. The variable speed drill ofclaim 24, wherein movement of the variable speed switch from the first position to the second position increases the power output of the motor.

26. The variable speed drill ofclaim 22, further comprising a mixing implement rotationally coupled to the motor.

27. A variable speed drill comprising:

a housing;

a motor within the housing having a lamination length of at least 30 millimeters and a lamination diameter of at least 65 millimeters and having a motor current rating greater than 8 amps and having a motor power level greater than 600 Watts;

a gear reduction mechanism drivingly connected to said motor;

a chuck drivingly connected to said gear reduction mechanism, wherein said drill has a maximum torque level at the chuck greater than 580 in-lbs

a variable speed switch mounted to the housing and operable to vary a power output of the motor; and

a mixing implement rotationally coupled to the chuck.

28. The variable speed drill ofclaim 27, wherein said drill has a weight greater than 5.5 pounds.

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