Electric Brusher

Abstract

An electric brusher includes an action which both rotates and reciprocates to provide good brushing action. The brush is secured to a driven shaft which is slidably mounted with respect to a rotary drive shaft and which is operably connected to the rotary drive shaft for rotation therewith. A cam wheel rotates with the drive shaft or the driven shaft and causes the driven shaft to reciprocate axially with respect to the drive shaft.

Description

BACKGROUND

This invention relates to an electric brusher, and, more particularly, to an electric brusher which is particularly suitable for use as a toothbrush.

Proper dental hygiene requires that the teeth be brushed in the proper manner. It has long been recognized that the manual brushing of teeth frequently includes improper brushing technique. For example, the labial surfaces of the teeth should properly be brushed in an up-and-down manner, while the occlusal surfaces of the teeth should be brushed by a back-and-forth motion across the tooth surface.

Since a person cannot always be depended upon to use the proper motion, particularly in the case of infants, electric toothbrushes have become popular in the last several years. However, even electrical toothbrushes have not provided completely satisfactory operation. Most electric toothbrushes provide merely a simple up-and-down brushing action or a simple reciprocating brushing action. If the brush moves up and down, it tends to push the gum away from the base of the tooth and creates a sensitive and vulnerable area at the gum line which is prone to decay.

In contrast to a simple up-and-down motion, the preferred brushing action is a downward stroke of the toothbrush on the upper teeth away from the upper gums and an upward stroke of the brush for the lower teeth, always brushing away from the gum line toward the occlusal surfaces of the teeth and not toward the gum line.

SUMMARY

The invention provides an apparatus with the desired brushing action. The toothbrush can be provided selectively with rotary motion in one direction, rotary motion in the other direction, reciprocating motion, or both reciprocating motion and rotary motion in one or the other direction simultaneously. The brush is connected to a driven shaft which is rotated by a drive shaft powered by a conventional reversible electric motor. The driven shaft is mounted for axial sliding movement relative to the drive shaft, and a cam wheel mounted for rotation with either the driven shaft or the drive shaft causes the driven shaft to reciprocate axially with respect to the drive shaft.

DESCRIPTION OF THE DRAWINGS

The invention is explained in conjunction with illustrative embodiments shown in the accompanying drawing in which

FIG. 1 is a perspective view, partially broken away, of an electric toothbrush formed in accordance with the invention;

FIG. 2 is a broken perspective view of another embodiment of the invention;

FIG. 3 is an enlarged fragmentary sectional view taken along the longitudinal centerline of FIG. 1;

FIG. 4 is an exploded view of some of the components of the toothbrush of FIG. 1;

FIG. 5 is a sectional view taken along the line 5--5 of FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The invention will be explained with reference to a toothbrush designated generally by numeral 10 in FIG. 1. In the embodiment illustrated, the toothbrush 10 includes an elongated, generally cylindrical outer casing or frame 11 which encloses a conventional rechargeable direct-current electric motor 12 and a rechargeable battery 13. However, it is to be understood that the motor could be powered by other means, for example, by a 110 volt voltage-dropping transformer, or the motor could be powered hydraulically. A cylindrically shaped toothbrush 14 mounted on brush shaft 15 extends forwardly from the front wall 16 of the casing, and conventional 110 volt a.c. terminals 17 extend rearwardly from the rear end 18 of the casing.

The terminals 17 are adapted to plug into a standard 110-115 volt, single phase, 60 cycle conventional recharging stand which recharges the battery 13 when the toothbrush is not in use. The recharging stand permits the direct current battery to be charged by alternating current, and also may serve as a brush holder for the removable brush and brush shaft. The motor 12 includes a first contact 19 which electrically engages one of the terminals 20 of the battery and a second contact 21 engaging the other terminal (not shown) of the battery.

The electric motor 12 includes a rotary drive shaft 22 which extends axially within the cylindrical casing 11 and which is telescopingly or slidably received by a generally cylindrical driven shaft 23 having an internal diameter slightly larger than the outside diameter of the drive shaft 22. Referring to FIGS. 3-5, the drive shaft 22 is provided with a pair of diametrically opposed axially extending grooves 24 which receives a plurality of steel ball bearings 25. The interior wall of the cylindrical driven shaft 23 is also provided with diametrically opposed axially extending grooves 26, and the grooves 24 and 26 are seen to be generally arcuate in cross section having approximately the same radius as that of the ball bearings. The outside diameter of the drive shaft 22, the inside diameter of the driven shaft 23, the depth of the grooves 24 and 26, and the diameter of the ball bearings are all correlated to permit the drive shaft to be slidably received by the driven shaft so that the ball bearings 25 provide sliding bearing action for the relative axial sliding movement of the two shafts while operatively connecting the two shafts against relative rotational movement in the manner of a splined connection. Thus, as the rotary drive shaft 22 rotates in one direction, the driven shaft 23 is caused to rotate with the drive shaft by the ball bearings.

The forward end of the driven shaft 23 extends through a suitable opening 27 in the forward wall of the casing 11 and is slidably and rotatably mounted by means of annular bearing 28. The bearing 28 is in turn rotatably mounted within the opening in the forward wall of the casing by means of ball bearings 29 which are contained within suitable grooves provided in the bearing 28 and the forward wall 16.

The brush 14 is seen to be generally cylindrically shaped and is carried by the brush shaft 15 which is received by the forward end of the driven shaft 23. The rearward end of the brush shaft 15 includes a pair of radially outwardly extending ribs or flanges 30, and the end of the brush shaft is provided with a circumferentially extending annular groove 31.

The forward end of the driven shaft 23 is provided with axially extending slots 32 which receive the ribs 30 on the brush shaft and secure the brush shaft 15 for rotation with the driven shaft 23. The outer surface of the driven shaft is provided with a circumferentially extending groove 33, and an opening 34 is provided in the groove through the wall of the driven shaft. A generally C-shaped spring clip 35 which includes an inwardly extending generally V-shaped locking portion 36 is sized to be received in the groove 33 so that the locking portion 36 extends through the opening 34 to engage the groove 31 on the brush shaft, thereby preventing withdrawal of the brush shaft from the driven shaft. The resilient retainer clip 35 may readily be flexed to permit withdrawal of the brush shaft from the driven shaft when it is desired to change brushes.

A generally cylindrical hardened steel cam wheel 38 is mounted on the rearward end of the driven shaft 23 and includes a generally planar annular forward surface 39 and a rearward, contoured cam surface 40 which includes a camming portion 41 extending rearwardly from the remainder of the surface 40. A helical compression spring 42 (shown partially broken away) is ensleeved on the driven shaft between the forward wall 16 of the casing and the cam wheel 38 and urges the driven shaft rearwardly with respect to the forward wall 16. The diameter of the helical spring may be such that the forward end thereof engages the annular bearing 28 which rotates in the same direction as the driven shaft, although perhaps at a slower rate since the driven shaft is slidably received by the bearing 28. The rearward end of the spring engages the annular forward surface 39 of the cam wheel, and the spring therefore may rotate at approximately the same speed as the driven shaft so that friction between the spring and the driven shaft is minimized.

Referring to FIGS. 1 and 5, the cam wheel 38 is engageable with a cam block or abutment 43 which is pivotally mounted on the casing 11 by means of pivot pin 44 for pivotal movement in a plane perpendicular to the axis of the driven shaft. The cam block 43 includes a cam engaging end 43a which is engageable with the camming surface 40 of the cam wheel and a lever end 43b which extends through an opening in the casing. The cam block is anchored against axial movement, and when the cam block is in the position illustrated in FIGS. 1 and 5, the spring 42 urges the cam wheel against the cam block. As the driven shaft is rotated by the drive shaft, the camming surface 40 of the cam wheel rotates against the cam block 43. As the camming portion 41 of the cam wheel approaches the cam block, the driven shaft and the brush 14 are moved axially forwardly against the resilient urging of spring 42. As the cam portion 41 rotates beyond the cam block, the driven shaft and brush are urged rearwardly by the spring to their original positions. The particular cam wheel illustrated has one rearwardly extending cam portion 41, and the brush 14 therefore makes one complete reciprocation for each revolution of the drive shaft.

If it is desired to have the brush merely rotate and not reciprocate, the camming end 43a of the cam block 43 may be pivoted out of engagement with the cam wheel by pressing the lever end 43b which extends exteriorly of the casing.

The amount of relative sliding movement of the shafts 22 and 23 can be limited by correlating the number of balls and the length of the grooves 24 and 26. Referring to FIG. 5, the ends of groove 24 are provided by forward and rearward shoulders 22a and 22b , respectively. Groove 26 extends from shoulder 23a to the rearward end 23b of the shaft 23. The rearward end of the groove 26 is closed by a radially inwardly extending shoulder 45 on the cam wheel 38, and the cam wheel can be conveniently mounted on the driven shaft by providing the driven shaft with external screw threads 46 which engage corresponding threads in the cam wheel.

The lengths of the grooves 24 and 26 are approximately the same, and the number of ball bearings is selected so that the groove length is greater than the total axial length of the bearings by at least the distance of reciprocation caused by the cam. For example, in one embodiment of the invention, the cam caused reciprocation of about one-eighth inch, and the total axial length of the bearings was about one-fourth inch less than the lengths of the grooves.

The driven shaft 23 can move to the left from the position illustrated in FIG. 5 until the shoulder 45 of the cam wheel forces the ball bearings against the shoulder 22a which provides the forward end of the groove 24. The shaft 23 can move to the right until the shoulder 23a of the shaft 23 forces the ball bearings against the shoulder 22b of the shaft 22. These shoulders therefore act as stop means to prevent withdrawal of the driven shaft from the casing and to limit the inward movement of the driven shaft under the urging of the spring 42 when the cam block 43 is pivoted away from engagement with the cam.

The shafts can be assembled by inserting the shaft 22 part way into the shaft 23, inserting the ball bearings into the grooves, and then threading the cam wheel onto the shaft 23 to close the groove 26.

A sliding three-position switch 47 is mounted on the casing for turning the motor on and off. Advantageously, the motor is reversible, and the switch 47 may be moved to provide the desired direction of rotation of the drive shaft.

If the toothbrush 10 as shown in FIG. 1 is grasped by the right hand and is to be used to brush the lower teeth, the switch 47 can be moved to cause the electric motor to rotate the brush 14 in the direction of the arrow A so that the brush will brush upwardly from the gum line toward the occlusal surfaces of the lower teeth. At the same time, the cam block 43 can be positioned so that the driven shaft and the toothbrush either reciprocate or do not reciprocate with respect to the drive shaft. When the upper teeth are to be brushed, the switch 47 is moved to reverse the rotation of the drive shaft 22 and cause the brush to rotate in the direction indicated by the arrow B. Again, the cam block may be positioned to provide reciprocation or no reciprocation as desired.

When the occlusal surfaces are being brushed, it is generally desired to provide reciprocating action to the brush along with rotary action in either direction, and reciprocating motion may be imparted to the brush by moving the cam block so that the camming end thereof engages the cam wheel as the cam wheel rotates.

The driven shaft 23 is seen to include an axial extending slot 47 which extends for a majority of the length of the shaft, and we have found that this slot may be helpful for machining the grooves 26 which are provided in the inner wall of the driven shaft for the bell bearings 25.

A modified toothbrush 50 is illustrated in FIG. 2 and includes an elongated casing 51, a reversible d.c. motor 52 which is powered by a rechargeable battery (not shown) similar to the battery 13, and recharging terminals 54 adapted to be plugged into a recharging stand.

A hardened cam wheel 55 which is mounted directly on the rotary drive shaft 56 of the motor for rotation therewith. A gear wheel 57 is also carried by the drive shaft 56, and the forward end of the drive shaft may be journaled in a suitable bearing 58 which is mounted on the forward wall 59 of the casing.

A secondary drive shaft 60 extends parallel to the drive shaft 56 and the rearward end thereof is journaled in bearing 61 mounted within the casing. The forward end of the shaft 60 is slidably received by driven shaft 62 in the same manner as described with respect to the drive shaft 22 and the driven shaft 23. Thus, each of the outer wall of the shaft 60 and the inner wall of the hollow driven shaft 62 is provided with a pair of diametrically opposed axially extending grooves which cooperate with steel ball bearings which permit relative axial sliding movement but lock the two shafts against relative rotational movement. It will be understood that other types of splined connections may be used which will lock the cooperating shafts against relative rotational movement while permitting relative axial movement.

The forward end of the driven shaft 62 may be rotatably and slidably mounted in the forward wall 59 of the casing as described hereinbefore with respect to the driven shaft 23, and a toothbrush shaft 63 carrying a brush 64 can be slidably received by the driven shaft and held by retaining clip 65.

The secondary drive shaft 60 carries a gear wheel 66 which meshes with the gear wheel 57 carried by the drive shaft 56. The rearward end of the driven shaft 62 includes a radially enlarged hardened steel wheel 67 which is engageable with the camming surface 68 of the cam wheel 55, and a compression spring 69 may be ensleeved on the reciprocating shaft 62 for resiliently urging the wheel 67 against the cam wheel.

As the drive shaft 56 rotates, the shaft 60 will also rotate, although in the opposite direction. Rotation of the drive shaft 56 also causes rotation of the cam wheel 55, and the camming surface 68 thereof causes the driven shaft 62 to reciprocate while it is rotating.

If desired, the cam wheel may be mounted on the rearward end of the driven shaft 62, and the wheel 67 may be mounted on the drive shaft 56 for engagement with the cam wheel. Also, the driven shaft may be geared up or down with respect to the drive shaft 56 by selecting a desired gear ratio for the gears 57 and 66.

While we have described our invention with particular reference to a toothbrush, it will be understood that our reciprocating and rotary brush can be used for many purposes other than dental hygiene.

While in the foregoing specification, we have set forth detailed descriptions of specific embodiments of our invention for the purpose of illustration, it is to be understood that many of the details hereingiven may be varied considerably by those skilled in the art without departing from the spirit and scope of our invention.

Claims

We claim:

1. An apparatus comprising a casing, a motor mounted in the casing, the motor having a rotary drive shaft, a driven shaft rotatably and slidably mounted in the casing, the driven shaft being movable axially relative to the drive shaft, means connecting the drive shaft and the driven shaft for rotating the driven shaft as the drive shaft rotates, a cam wheel mounted on the driven shaft for rotation therewith, and abutment means mounted on the casing and engageable with the cam wheel for reciprocating the cam wheel and the driven shaft axially as the cam wheel rotates, the abutment means being movable between a first position in which the abutment means is engageable with the cam wheel and a second position in which the abutment means is not engageable with the cam wheel whereby the driven shaft can be caused to reciprocate or not reciprocate as it rotates.

2. An electric apparatus comprising a casing, an electric motor mounted in the casing, the motor having a rotary drive shaft, a driven shaft rotatably and slidably mounted in the casing, the driven shaft and the drive shaft being telescopingly engaged and being secured against relative rotational movement whereby the driven shaft rotates with the drive shaft but is slidable axially relative thereto, a cam wheel mounted on the driven shaft for rotation therewith, abutment means mounted on the casing and engageable with the cam wheel for reciprocating the cam wheel and the driven shaft axially as the cam wheel rotates, the abutment means being movable between a first position in which the abutment means is engageable with the cam wheel as the wheel rotates and a second position in which the abutment means is not engageable with the cam wheel whereby the driven shaft can be caused to reciprocate or not reciprocate as it rotates, and a spring ensleeved on the driven shaft resiliently urging the cam wheel against the abutment means.

3. An apparatus for providing rotating and reciprocating movement to a driven shaft comprising a frame, a motor mounted on the frame having a rotary drive shaft, a driven shaft rotatably and slidably mounted on the frame, the driven shaft having an axially extending bore telescopingly receiving the drive shaft, the wall of the bore and the outer wall of the drive shaft each having an axially extending groove, ball bearing means between the driven shaft and the drive shaft received by the grooves for securing the driven shaft and the drive shaft against relative rotational movement while permitting relative axial sliding movement, ball retaining means removably secured to the end of the driven shaft which receives the drive shaft, the ball retaining means having a shoulder extending radially inwardly beyond the groove of the driven shaft to prevent the escape of the ball bearings, a cam mounted on the driven shaft for rotation therewith, and abutment means mounted on the frame and engageable with the cam for reciprocating the cam and the driven shaft axially as the cam rotates.

4. The apparatus of claim 3 in which the ball retaining means includes an annular ring threadedly received on the end of the driven shaft.

5. The apparatus of claim 3 in which the ball retaining means and the cam is provided by an annular ring threadedly received on the end of the driven shaft and having a cam surface.