Patent Description:
The present disclosure relates to an apparatus for adjusting the stroke of random orbital machine, such as, but limited to, polishing machines, sanding machines and massaging machines. The adjustability allows the user to define the stroke of the random orbital machine and adjust it between a maximum definitive stroke setting and a minimum <NUM> orbital setting.

Polishing machines and sanding machines are routinely used in the automotive detailing industry and home building industry to correct imperfections in the paint or drywall and to apply polishes and waxes. There are three primary machines used, including rotary buffers, random orbital machines, and dual action machines. Each tool has its place, as the manner in which the pad spins on each machine is unique and used for different purposes.

Rotary buffers are the fastest and most effective machine for removing paint defects in a controlled manner with good results. The drive unit used in a rotary buffer is directly connected to the pad and each one is in axial alignment with each other. In order to correct paint scratches, the rotary buffer is commonly used to remove enough paint surrounding the scratches to make the surface level. Removing scratches, however, requires more skill and control of the machine than a typical hobbyist possesses. For this reason, rotary buffers are commonly avoided by average users as it is very easy to remove too much paint and damage the finish by causing swirl marks or by burning the paint.

Random orbital machines were introduced in order to meet the needs of an average user, as they require less experience and control to operate. A random orbital machine uses a gear case that employs two unique mechanisms which move a pad attached to a backing plate. Unlike a rotary buffer, random orbital machines place the central rotational axis of the pad and the backing plate offset from the driveshaft of the machine. This offset is commonly referred to as the "stroke". As a result, the backing plate and pad orbit the driveshaft in a circular motion. At the same time, the pad randomly spins, as it is mounted on an idle bearing. This random spinning varies with pressure applied on the pad and is not directly powered. The result is a polishing action that will not burn or cut through the paint as it will not produce the heat from a powered spinning action. Random orbital machines are, therefore, much safer and dramatically less likely to cause swirls or burn through the paint.

Similar to random orbital machines, dual action machines place the central rotational axis of the pad and the backing plate offset from the driveshaft. As a result of this stroke, the backing plate and pad orbit the driveshaft in a circular motion. However, with a dual action machine the spinning of the pad is directly powered.

At the heart of a random orbital machine is the machine's stroke. The stroke is determined by the offset between the driveshaft axis and the backing axis. A longer offset or stroke places the backing plate rotational axis farther away from the driveshaft axis. Multiplying the offset by two produces the stroke diameter. The "stroke" is, therefore, a term that identifies the diameter of the path the backing plate travels as it orbits around the driveshaft.

A majority of random orbital machines are small stroke machines, which mean they use a stroke length that measures somewhere between approximately <NUM> - <NUM>. A small stroke machine limits the movement of the pad to a smaller and tighter orbit. This results in a smoother action. A small stroke machine is also easier to control because the backing plate orbits around the driveshaft rotational axis in a tighter path. There are less vibrations and movement making the machine easier to hold due to the smoother action.

A large stroke machine delivers increased orbits per minute (OPM) of backing plate motion using the same rotations per minute (RPM), as the orbit of the backing plate and the pad around the drive shaft is increased. A large stroke also increases movement of the pad which helps spread out polishing compounds and treats a larger surface area. It also accomplishes more cutting action into the paint which allows for scratches and paint defects to be corrected. Small stroke machines typically only polish the paint and do not cut into it, and, therefore, are not able to remove surface defects.

One method of addressing the deficiencies of a small stroke has been to increase the RPM of the machine. While this increases the rotation of the motor, the machine stroke stays the same. There are also longevity issues associated with increased RPM for the motor and increased OPM for the pad. Increasing the RPM puts more strain on the motor, while increased OPM burns out a pad faster.

In sum, both long stroke and short stroke machines have their place in the industry. Therefore, what is needed is a machine that can be adjusted by the user without special tools or disassembly of the machine. Finally, what is needed is a compact, simple, and effective method to adjust the stroke of a machine based on the needs of the user.

Prior art in this technical field is in example known from publications <CIT> and <CIT>.

According to the invention, an adjustable stroke device for a random orbital machine as defined by claim <NUM> is claimed. Such an adjustable stroke device comprises a housing having a central axis and a wall defining a cavity. The housing including a drive hub and cover. At least a counterweight is movably disposed at least partially within the cavity. A mounting assembly is disposed at least partially within the cavity. The mounting assembly includes a workpiece attachment mechanism. A stroke adjuster couples the at least one counterweight with the mounting assembly. The stroke adjuster enables the at least one counterweight and mounting assembly to move with respect to one another such that a distance between the at least one counterweight and the mounting assembly may be variable adjusted which, in turn, variable adjust the stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing. The stroke adjuster includes an adjuster ring and a cam mechanism secured to the adjuster ring. The adjuster ring surrounds the wall of the housing. The adjuster ring is only rotatable around the central axis. The counterweight engages the cam mechanism which moves the counterweight in response to cam movement. The mounting assembly includes a bearing carriage engaging the cam mechanism. The mounting assembly moves in response to cam movement. The workpiece attachment mechanism further comprises a spindle coupling with the bearing carriage. A locking mechanism is associate with the mounting assembly to lock the drive in a rotational only position. The cam mechanism is directly secured to the stroke adjuster. At least one detent secures the stroke adjuster in position. Preferably a plurality of detents is used with each detent securing the stroke adjuster in a different separate position. The counterweight is fully disposed in the cavity.

A rotating tool, not part of the invention, comprises a housing and the motor, the motor including a drivetrain. An adjustable stroke device is coupled with the drivetrain. The adjustable stroke device comprises a housing having a central axis and a wall defining a cavity. The housing including a drive hub and cover. The drive hub is rotatably coupled with the drive train. At least a counterweight is movably disposed at least partially within the cavity. A mounting assembly is disposed at least partially within the cavity. The mounting assembly includes a workpiece attachment mechanism. A stroke adjuster couples the at least one counterweight with the mounting assembly. The stroke adjuster enables the at least one counterweight and mounting assembly to move with respect to one another such that a distance between the at least one counterweight and the mounting assembly may be variable adjusted which, in turn, variable adjust the stroke radius of the workpiece attachment mechanism with respect to the central axis of the housing. The stroke adjuster includes an adjuster ring and a cam mechanism secured to the adjuster ring. The adjuster ring surrounds the wall of the housing. The adjuster ring is only rotatable around the central axis. The counterweight engages the cam mechanism which moves the counterweight in response to cam movement. The mounting assembly includes a bearing carriage engaging the cam mechanism. The mounting assembly moves in response to cam movement. The workpiece attachment mechanism further comprises a spindle coupling with the bearing carriage. A locking mechanism is associate with the mounting assembly to lock the drive in a rotational only position. The cam mechanism is directly secured to the stroke adjuster. At least one detent secures the stroke adjuster in position. Preferably a plurality of detents is used with each detent securing the stroke adjuster in a different separate position. The counterweight is fully disposed in the cavity.

The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present invention, which is defined by the claims.

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention, which is defined by the claims.

Turning to the figures, a tool is illustrated with an adjustable stroke device and is designated with the reference numeral <NUM>. The tool includes a motor <NUM>, a power source <NUM> and a switch <NUM> for activating and deactivating the power source. The power source is shown as a cord but could be rechargeable batteries. The motor includes a pinion <NUM> positioned inside the head housing <NUM> of the tool. The drivetrain head housing <NUM> includes a cavity to house a drivetrain <NUM>. The drivetrain <NUM> includes a bevel gear <NUM> meshing with the pinion <NUM>. The bevel gear <NUM> is coupled with the adjustment stroke device <NUM> which is mounted, via a housing <NUM>, with the bottom of the head housing <NUM>.

The adjustment stroke device <NUM> includes a drive hub <NUM>, a workpiece mounting assembly <NUM> as a mounting assembly <NUM>, a counterbalance mechanism <NUM> as a counterweight <NUM>, a stroke adjustment mechanism <NUM> as stroke adjuster <NUM> and a cover <NUM>. The drive hub <NUM> and cover <NUM> form a housing defining a cavity.

The drive hub <NUM> includes a body <NUM> having a flange <NUM> and a pair of wings <NUM>. A driveshaft <NUM> extends from the body <NUM> and a bearing <NUM>. The flange <NUM> is positioned around an extending flange <NUM> on the housing <NUM>. The driveshaft <NUM> passes through the housing <NUM> and is received by an additional bearing <NUM> in the drivetrain head housing <NUM>. Ultimately, the driveshaft <NUM> is coupled with the bevel gear <NUM> to provide rotation to the drive hub <NUM>.

The drive hub wings <NUM> are separated by openings that receive the wings <NUM> from the cover <NUM> to form the cylindrical housing.

An inner body surface <NUM> is formed on the body <NUM> between the wings <NUM> (see <FIG>). The surface <NUM> provides a cutout to receive the cam plate <NUM> of the stroke adjustment mechanism <NUM>. Also, the inner surface <NUM> includes a plurality of detent bores <NUM>. Two detent bores <NUM> are shown, however depending upon the number of positions of the adjustable stroke device <NUM>, more bores may be included. The detent bores <NUM> receive detent pins <NUM>. The function of the detent pins <NUM> will be explained later.

The stroke adjustment mechanism <NUM> includes a ring <NUM> as adjuster ring <NUM> and a cam <NUM> as part of a cam mechanism. The ring <NUM> is positioned around the drive hub <NUM> and cover <NUM> as illustrated in <FIG>. The ring <NUM> includes a cam plate <NUM> directly secured to the ring <NUM>. The cam plate <NUM> includes cam slots <NUM> and detent holes <NUM>. The ring <NUM> is manually manipulated, rotated, by the user to move the adjustable stroker device <NUM> between operating positions. Also, a shaft <NUM> extends from the cam plate <NUM>. The shaft <NUM> fits in a bore <NUM> in the body <NUM>. This enables rotation of the stroke adjustment mechanism <NUM> and the drive hub <NUM>. The cam plate <NUM> secures the stroke adjustment mechanism <NUM> with the drive hub <NUM>. Generally, this is accomplished via a C-clip.

The workpiece mounting assembly <NUM> includes a bearing carriage <NUM> and a U-shaped body portion <NUM>. The bearing carriage <NUM> receives bearing <NUM> and a spindle <NUM>. The spindle <NUM> extends through the bearings and bearing carriage <NUM>. It has an external portion <NUM> that includes a threaded bore <NUM> to receive a backing plate <NUM> and fastener <NUM>. The adjustment workpiece mounting assembly <NUM> also includes a locking gear <NUM>. The locking gear <NUM> engages the counterbalance mechanism <NUM> to lock the workpiece mounting assembly <NUM> in a pure rotation position.

The U-shaped body portion <NUM> includes a pin <NUM>. The pin <NUM> is received in one of the cam slots <NUM>. Thus, the workpiece mounting assembly <NUM> is moved with respect to the counterbalance mechanism <NUM> upon rotation of the stroke adjustment mechanism <NUM>.

The counterbalance mechanism <NUM> includes a body <NUM> with a plurality of step portions <NUM>. The body <NUM> has an overall ring shape with an elliptical configuration. The inner surface of the body <NUM> includes a plurality of teeth <NUM>. The teeth <NUM> engage with the locking gear <NUM> as mentioned above to position the adjustable stroke device <NUM> in a purely rotational position. One of the steps <NUM> include a pin <NUM> that is positioned in one of the cam slots <NUM>. The pin <NUM> is positioned in the slot <NUM> opposite of the workpiece mounting assembly pin <NUM>. Thus, as the stroke adjuster ring <NUM> is rotated, the counterbalance mechanism <NUM> and the workpiece mounting assembly <NUM> are moved away or towards one another. In the purely rotation position, the lock gear <NUM> engages the teeth <NUM> as illustrated in FIG.

The cover <NUM> includes a base <NUM> that covers the bottom of the stroke adjuster <NUM>. The spindle portion <NUM> extends through the cover base opening <NUM> to enable connection with the backing plate <NUM>. The cover wings <NUM> insert in the openings between the drive hub wings <NUM>. This provides a substantially continuous cylindrical housing. The cover <NUM> is secured to the drive hub <NUM> via screws <NUM>. Thus, the counterbalance mechanism <NUM> as well as the workpiece mounting assembly <NUM> are positioned inside of the cover <NUM> and drive hub <NUM> housing.

Turning to <FIG>, the detent pins <NUM> are illustrated. The detent pins <NUM> are received in the cam plate holes <NUM> locking the stroke adjustment mechanism <NUM> in a rotary mode position or in a dual action mode position. A biasing member is positioned in the bore <NUM> so that upon rotation of the stroke adjustment mechanism <NUM>, the cam plate <NUM> can move over the detent pin <NUM> into the next position where the detent pin <NUM> is received in another detent hole <NUM>.

Also, as can be seen in FIGS. 6A and 6B, the cam plate <NUM> is positioned on the inner surface <NUM> of the hub body <NUM> defined by the cutout. The cam plate <NUM> rotates on the surface between positions.

In operation, the stroke adjustment mechanism <NUM> ring <NUM> is rotated. As this occurs, the detent pins <NUM> are biased away from the cam plate <NUM> releasing the cam plate <NUM> from the detent pins <NUM>. The ring <NUM> continues to turn or rotate until the detent pin <NUM> engages the next detent hole <NUM> in the cam plate <NUM>. As this occurs, the adjustable stroke device <NUM> is locked into a position. The positions move from a purely rotational position to a dual action position.

As the ring <NUM> is rotated, the pins <NUM>, <NUM> in the slots <NUM> are moved. As this occurs, the workpiece mounting assembly <NUM> and counterbalance mechanism <NUM> are moved either toward one another or away from one another. In a rotary only position, the workpiece mounting assembly locking gear <NUM> engages the teeth <NUM> of the counterbalance mechanism <NUM>. This provides rotational only movement. As the workpiece mounting assembly <NUM> and counterbalance <NUM> mechanisms are moved away from one another, the workpiece mounting assembly <NUM> freely rotates in the counterweight <NUM> and housing providing the dual action rotary and orbital movement.

Claim 1:
Adjustable stroke device (<NUM>) for a random orbital machine (<NUM>) comprising:
a housing (<NUM>, <NUM>) having a central axis and a wall defining a cavity;
at least one counterweight (<NUM>) movably disposed at least partially within the cavity;
a mounting assembly (<NUM>) disposed at least partially within the cavity, the mounting assembly (<NUM>) including a workpiece attachment mechanism (<NUM>, <NUM>, <NUM>, <NUM>); and
a stroke adjuster (<NUM>) coupling the at least one counterweight (<NUM>) with the mounting assembly (<NUM>), the stroke adjuster (<NUM>) enabling the at least one counterweight (<NUM>) and mounting assembly (<NUM>) to move with respect to one another such that a distance between the at least one counterweight (<NUM>) and the mounting assembly (<NUM>) may be variably adjusted which, in turn, variably adjust a stroke radius of the workpiece attachment mechanism (<NUM>, <NUM>, <NUM>, <NUM>) with respect to the central axis of the housing (<NUM>, <NUM>),
characterized in the stroke adjuster (<NUM>) including an adjuster ring (<NUM>) and a cam mechanism (<NUM>, <NUM>, <NUM>) secured with the adjuster ring (<NUM>).