MXPA06008090A - Integrated brush-holder retention system - Google Patents

Abstract

A brush-holder system for an electric motor which has a rotating commutator in a first motor housing portion, the assembly includes a second motor housing portion connected to the first motor housing portion and having at least one brush holding pocket therein. The pocket is formed by a structure of the second motor housing portion which defines a support surface on one side thereof and a bridge portion on an opposite side thereof. The system further includes an elongated brush having first and second ends, wherein the first end is configured to be coupled to a biasing member and the second end is configured to contact the motor commutator, and at least one removable brush-holder having a first open end configured to receive the brush therein and to fit in the pocket, and a second open end enabling the brush to extend outwardly therefrom to contact the motor commutator.

Description

INTEGRATED PORTA CONSOLE RETENTION SYSTEM FIELD OF THE INVENTION The present invention generally relates to electric motors and very particularly to brush holder systems for electric motors.

BACKGROUND OF THE INVENTION The electric motors that are used in motorized hand tools as well as other applications, usually use brushes to provide electrical interconnection with a motor switch. As is known in the art, the brushes that are used in electric motors are disposable articles and must be periodically replaced during the duration of an engine that uses them. The motors that are used to power hand tools such as electric drills, saws and the like, necessarily have a system to hold the brushes that are used in the motors. Because the motor brushes have a life that is much shorter than that of the tools in which they are used, it is often necessary to periodically replace brushes that are worn, which, in general, is much less expensive. for a user to replace the entire tool. Although there have been many different designs of motors and their brush holder systems, it was common for prior systems to have brushes that were carried by the brush holders assembled in a motor housing that was secured with rubber pads, screws, caps and the like. Although some designs were easier to use than others since the brushes could be replaced more simply, many prior art configurations were not as convenient and adaptable to the periodic maintenance of replacing the motor brushes that was necessary for the operation of the engines. Although the prior art designs used brush holders that were often mounted on the engine cover, for example, this type of design offered some advantages over previous designs in terms of the ease of replacing the brushes. However, it was found that motorized hand tools that had brushes mounted on the covers, often experienced unequal performance because such motorized hand tools were susceptible to drops or crashes in one form or another.

Occasionally, this resulted in some dysfunction or reduced performance due to the fact that the force of impact from any source was imparted to the assembly of brush holders or the brushes themselves. A desirable goal is designs that insulate brushes against the impact resulting from a tool fall or, otherwise, that are subject to abuse.

SUMMARY OF THE INVENTION Preferred embodiments of the present invention provide an integrated brush holder system that allows the brushes to be easily installed and replaced in an engine without the use of screws, rubber pads, lids or the like. The brushes are also isolated from the lid and, therefore, are relatively isolated from any impact that could be applied to the lid. This insulation prevents the force of an impact from being transferred from the cover to the brush holders and brushes themselves. The preferred embodiment of the present invention has a brush holder that is configured to accept a brush therein, the replacement of which can easily be achieved without the use of special tools. The brush holder can be assembled into the motor by its simple insertion into a receptacle structure and the brush holder interacts with the receptacle structure to firmly hold the brush holder. The brushes as well as the brush holder itself can be easily removed without special tools, which facilitates the replacement of the brush holder or the brushes themselves. The construction features in the motor housing interact with the construction of the brush holder so that the brush holder will be accurately positioned when inserted into the motor housing. Additionally, the brushes can be replaced without removing the associated brush holder if desired.

DETAILED DESCRIPTION OF THE FIGURES Figure 1 is a top view of a substantial portion of a motor housing together with motor components and a brush holder; Figure 2 is a cross-section in simplified diagram taken generally through the axis of an engine having a pair of brush holders, according to the preferred embodiment of the present invention; Figure 3 is an enlarged illustration of a portion of the preferred embodiment shown in Figure 2; Figure 4 is a side view of the brush holder shown in Figure 3; Figure 5 is a top view of the brush holder shown in Figures 3 and 4; Figure 6 is an end view of the brush holder shown in Figure 3; Figure 7 is a top view of the motor housing of the preferred embodiment of the present invention; Figure 8 is a side view of the motor housing of the present embodiment; Figure 9 is a perspective view of a portion of the motor housing illustrating the receptacle of the brush holder of the motor housing where the brush holder and brushes are assembled; Figure 10 is a perspective view of the portion of a brush holder that is shown together with a brush assembly, in accordance with the preferred embodiment of the present invention; and Figure 11 is a perspective view of the portion of a brush assembly, in accordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The preferred embodiment of the integrated brush holder system of the present invention comprises a motor housing that is configured to receive at least one and, preferably, a pair of brush holders, wherein each of the brush holders includes a motor brush in the same. Preferably, the brush holders are positioned to oppose each other diametrically on opposite sides of a switch of an electric motor. Turning now to the figures, Figure 1 illustrates a perspective view of a portion of a motor housing, indicated generally by the numeral 10, wherein a brush holder is shown, indicated generally by the numeral 12, wherein the brush holder 12 has a brush assembly in it. Although Figure 1 illustrates a single brush assembly 12, it should be understood that a second brush holder assembly is provided and would be located on the opposite side of a switch 14 shown in Figure 1, the second brush holder being illustrated at 16 in FIG. Figure 2. Returning to Figure 1, the motor housing 10 has a generally cylindrical outer portion 18 from which four structural frame elements 20, 22, 24 and 26 extend upwardly at an angle to a generally flat circular end. 28 that provides an exterior structure where an engine is located. The elements 24 and 26 include a pair of flat protuberances 30, each of which has a threaded hole 32 therein, where screws (not shown) can be inserted into an end plate (not shown) for installing an end plate of the motor housing 10. It should be appreciated that the brush holders 12, 16 are not directly connected to the end plate and, therefore, should not be damaged if the end plate is struck, such as would occur if the tool, where the preferred mode is installed, is dropped or suffers. Referring now to Figures 3, 4, 5 and 6, the brush holder 12 is a generally rectangular structure configured to receive a generally rectangular brush 34 at a receiving end 36 of the brush holder. The side walls 38 are downwardly dependent from an upper portion 40, wherein the downwardly extending legs 42 are received within a lower structure 44. The lower structure 44 is preferably composed of an electrically insulating material., such as Bakelite for example, and the downwardly extending legs 42 are preferably placed in place before the bottom structure 44 is formed. Unlike the bottom structure 44, the balance of the brush holder 12 is preferably composed of an electrically conductive metal material. Preferably, the brush holder 12 further includes features for promoting a snug fitting coupling within a brush holder receptacle, the brush holder receptacle being generally indicated at 46 in Figure 9. Returning to Figures 3-6, the bottom structure of the brush holder 44 preferably includes a pair of side rails 48. Preferably, wherein a space, between the side rails 48 in a bottom portion of the lower structure, defines a generally rectangular channel (not shown). At one end of the lower structure 44 towards the receiving end 36 of the brush holder 12, the lower structure preferably includes a downwardly depending end flange 52. Thus, the end flange 52 forms a support 52a in the part below the lower structure 44. The u portion 40 preferably includes at least one locking tab 54, which is a generally thin rectangular-shaped structure that is biased to extend at least slightly upwardly from the portion u, and is bounded on three sides by a generally U-shaped cavity 56. Additionally, a contact tab is also provided to ensure continuous operation until the brush is sufficiently worn that it needs to be replaced, said tab is preferably provided in the u portion 40 which is also configured to be deflected at least slightly upwards and it is bounded on three sides by a generally U-shaped cavity 60. Optionally, the contact tab 58 may be provided to complete the electrical connection with the motor or other electronically controlled device, such as a speed control device or other terminal. . Correspondingly, as shown in Figure 9, the brush holder pocket 46 is defined on its sides by side walls 62 extending radially inwardly from a circumference of the cylindrical outer portion 18 of the motor housing 10. A surface bottom 64 of the brush holder housing 46 comprises the side walls 62 at least along a portion of the length of the side walls, and is defined at an inner edge by a tapered grill 66 having a curved cavity 68 placed in the same A generally circular hole 70 is positioned within the lower surface 64 adjacent the tapered grill 66. A bridge 72 is positioned at a predetermined distance above the lower surface 64 supported by the side portions 74 extending upwardly from the walls. 62 laterals to the bridge. Preferably, a back support 76 is also provided on an inner portion of the brush holder receptacle 46, wherein the back support is coplanar with, but is spaced apart from the bottom surface 64 of the brush holder receptacle. Therefore, the brush holder 12 is generally configured and designed to receive the brush 34 in a tight manner, while also being configured and designed to be received snugly within the brush holder receptacle 46 that is positioned within the housing 10. Preferably, the brush holder 12 is inserted into the brush holder receptacle 46, with a switch end 77 of the brush holder, which is the end opposite the receiving end 36, the important entry being to the brush holder receptacle. A bridge height 72 is configured so that a bottom portion of the bridge slidably engages the u portion 40., while the lower part of the lower structure 44 is slidably coupled to the lower surface 64 of the brush holder receptacle 46. As the brush holder 12 continues to slide within the brush holder receptacle 46, the locking tab 54 encounters resistance, by exerting an upward force on the bridge 72, and because the bridge is fixed, the bridge in turn compresses the locking tab downwards. Additionally, additional movement is prevented when the end support 52a is butted with the tapered grill 66, in which position the bridge 72 is generally abutting one end of the locking tab 54. The rear support 76 preferably supports the switch end 77 in the bottom portion of the bottom structure 44. As shown in Fig. 10, the exemplary brush 34, which is described in conjunction with the invention, is an elongated brush having a rectangular cross-section that is only slightly smaller than a cross section of the generally rectangular brush holder 12. One end of the brush 34 that is inserted in the brush holder 12 includes a circular cylindrical protrusion 78 in which a deflection element, preferably a compression spring 80, is coupled, and which extends towards the receiving end 36 of the brush holder 12. To maintain the contact of the compression spring 80 with the brush 34, the invention further includes an end piece 84 which is configured and designed to engage the receiving end 36 of the brush holder 12 (best shown in Figure 4). Specifically, the end piece 84 is preferably a rectangular plate having a downwardly depending flange 86 that is configured to fit in a tightly fashion a correspondingly configured portion of the lower structure 44. Additionally, the end piece 84 of Preferably it includes lateral locking tabs 88 which extend along at least a portion of the side walls 36 of the brush holder 12 in a direction that is generally perpendicular to a plane of the end piece 84. Each of the tabs of lateral lock 88 preferably includes a locking protrusion 90 which is oriented inward towards the side walls 36 of the brush holder 12. In cases where the blocking protrusion 90 is provided, the side walls 36 include a corresponding locking hole 92 . Therefore, as the end piece 84 engages the contact end 82 of the brush holder 12, the downwardly depending flange 86 engages the bottom structure 44, while the locking protrusions 90, on each of the locking tabs. sideways 88, engage in a locked manner the respective locking hole 92 placed in any side wall 36 of the brush holder. Therefore, when the brush 34 engages the brush holder 12, the cylindrical protrusion 78 fits snugly to one end of the compression spring 80, while the other end of the compression spring is abutting the end piece 84. of the brush holder. Therefore, because the end piece 84 is stationary insofar as it is lockedly engaged to the brush holder 12, the compression spring 80 deflects the brush 34 in the direction of the switch end 77 of the brush holder. In this way, the brush 34 is pushed into contact with the switch 14. Additionally, as the brush 34 wears out, the compression spring 80 will undergo decompression, thus continuing with the push of the brush in the direction of the switch 14 to ensure continued operation until the brush is sufficiently worn that it needs to be replaced. A copper braided wire 94 is also fixed to the brush 34 as well as to the end piece 84, and a preferably insulated wire 96 extends to a connector 98 for electrically and physically connecting the brush to the motor. A conductive tab 100 extends upwardly from an upper end of the end piece 84 at an angle to the switch end 77 (best illustrated in FIG. 4) of the brush holder 12. Like the contact tab 58, the conductive tongue 100 may optionally be provided to maintain electrical contact with the motor or other electronically controlled device, such as a speed control device or other terminal. Although one or the other of the contact tab 58 and the conductive tab 100 may be present alone, in the preferred embodiment it is preferred to provide both to supply at least two electrical connections. The invention is particularly convenient since the brush holder 12 can be quickly and easily removed from the housing 10, and then the brush 34 placed inside the brush holder can be quickly and easily removed and replaced. To uncouple the brush holder 12 from the brush holder receptacle 46, the operator releases the locking tab 54 with a screwdriver or other tool while pulling the brush holder outwardly from the brush holder receptacle. With the locking tab 54 loose, the brush holder 12 can be slidably removed from the brush holder housing 46. To remove the brush 34 from the brush holder 12, the end piece 84 can be removed from the brush holder 12 by simply inserting a screwdriver (or other tool) between the side walls 38 and the side locking tabs 88 of the end piece. Therefore, the end piece 84 and the brush holder 12 can be easily separated from one another, allowing easy replacement of the brushes. In the preferred embodiment illustrated, the end piece 84 includes the conductive tongue 10 where the insulated wire 96 can be fixed, preferably through welding, although the joint can be made by crimping or the like. Similarly, the insulated wire 96 is corrugated or welded to the end piece 84. The composition of the brushes is conventional and is well known to those skilled in the art. Although various embodiments of the present invention have been shown and described, those skilled in the art will appreciate that other modifications, substitutions and alternatives can be made. These modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. Several characteristics of the invention are mentioned in the following claims.

Claims (15)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following is claimed as a priority: CLAIMS

1. - A brush holder system (10) for an electric motor that is of the type having a rotary switch that is hinged on a first motor housing portion, said assembly comprising: a second motor housing portion (72, 74) configured to be tightly connected to the first motor housing portion and to have at least one brush holder receptacle (46) therein, said receptacle is formed by a structure of said second motor housing portion which defines a surface of support on one side thereof and a bridge portion on an opposite side thereof; an elongate brush (34) having first and second ends, wherein said first end is configured to engage a deflection element and said second end is configured to come into contact with the motor switch; at least one removable brush holder (12) having a first open end configured to receive said brush in the same and to fit in said receptacle, and a second open end that allows said brush to extend outwards from there to enter in contact with the motor switch; a deflection element (80) coupled to said brush; and a cover (84) coupled to the first open end and configured to abut said diverting element to bias the brush toward the motor switch.

2. The brush holder system according to claim 1, further comprising two removable brush holders, each of said removable brush holders is configured to receive a brush therein.

3. The brush holder system according to claim 1, characterized in that said first end portion of said brush is also configured to be cylindrical.

4. The brush holder system according to claim 1, characterized in that said second housing portion comprises an electrically insulating material.

5. - The brush holder system according to claim 1, characterized in that said brush holder further comprises an insulating base portion.

6. The brush holder system according to claim 5, characterized in that said insulating base portion includes a pair of supports to limit the movement of the brush holder during insertion.

7. - The brush holder system according to claim 1, characterized in that said deflection element comprises a compression spring interposed between said cover and said first end portion for deflecting said brush towards the commutator.

8. The brush holder system according to claim 3, characterized in that said deflection element is coupled to said cylindrical end portion.

9. The brush holder system according to claim 1, characterized in that said brush holder further comprises a locking tab biased upwards from an upper surface thereof for coupling said bridge portion of said second motor housing portion.

10. The brush holder system according to claim 1, characterized in that said brush holder further comprises a first and second locking tabs.

11. The brush holder system according to claim 10, characterized in that said first locking tongue extends upwards to couple said bridge, and said second locking tongue extends upward to electrically couple the motor.

12. A removable brush assembly for an electric motor having a generally cylindrical motor switch, a motor housing having a structure defining at least one brush assembly supporting a receptacle and a bridge portion encompassing each receptacle, said brush assembly comprises: an elongated brush having first and second ends, wherein said first end is configured to engage with a diverting member and said second end is configured to come into contact with the motor switch; a removable brush holder having a first open end configured to receive said brush in the same and to fit in the receptacle, and a second open end that allows said brush to come into contact with the motor switch; a deflection member coupled to said brush; and a cap coupled to the first open end and configured to abut said diverting element to bias the wiper toward the motor switch.

13. The removable brush assembly according to claim 12, characterized in that said first end of said brush is configured to include a cylindrical portion.

14. The removable brush assembly according to claim 12, characterized in that said brush holder further comprises an insulating base.

15. The removable brush assembly according to claim 12, characterized in that a structure defining an opening of the receptacle supporting the brush assembly and the bridge portion comprises electrically insulating material.