Patent Publication Number: US-2022228653-A1

Title: Adjustable Stroke Device With Cam

Description:
FIELD 
     The present disclosure relates to adjustable orbital devices including, but not limited to polishers, buffers, sanders and massagers. 
     BACKGROUND 
     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 0 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&#39;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 6 mm-12 mm. 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. 
     SUMMARY 
     Accordingly to the disclosure, an adjustable stroke device for a random orbital machine 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. 
     Accordingly to a second embodiment, a rotating tool 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. 
     Further areas of applicability will become apparent from the description provided herein. 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 disclosure. 
    
    
     
       DRAWINGS 
       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 disclosure. 
         FIG. 1  is a perspective view of a rotating tool according to the disclosure. 
         FIG. 2  is a perspective view partially in cross-section of the tool of  FIG. 1 . 
         FIG. 3  is an exploded view of the adjustable stroke device. 
         FIG. 4  is a cross-section view along line  4 - 4  of  FIG. 1 . 
         FIGS. 5  is a cross-section view like  FIG. 4  with the stroke adjustor rotated 180°. 
         FIG. 6  is a cross-section view of  FIG. 1  along line  6 - 6  thereof. 
         FIG. 7  s a cross-section view like  FIG. 6  with the stroke adjuster being rotated. 
         FIG. 8  is a cross-section view like  FIG. 6  after rotation. 
         FIG. 9  is an exploded perspective of the adjustable stroke device housing. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Turning to the figures, a tool is illustrated with an adjustable stroke device and is designated with the reference numeral  10 . The tool includes a motor  12 , a power source  14  and a switch  16  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  18  positioned inside the head housing  26  of the tool. The drivetrain head housing  26  includes a cavity to house a drivetrain  22 . The drivetrain  22  includes a bevel gear  24  meshing with the pinion  18 . The bevel gear  24  is coupled with the adjustment stroke device  30  which is mounted, via a housing  32 , with the bottom of the head housing  26 . 
     The adjustment stroke device  30  includes a drive hub  34 , a workpiece mounting assembly  36 , a counterbalance mechanism  38 , a stroke adjustment mechanism  40  and a cover  42 . The drive hub  34  and cover  42  form a housing defining a cavity. 
     The drive hub  34  includes a body  44  having a flange  46  and a pair of wings  48 . A driveshaft  50  extends from the body  44  and a bearing  52 . The flange  46  is positioned around an extending flange  31  on the housing  32 . The driveshaft  50  passes through the housing  32  and is received by an additional bearing  54  in the drivetrain head housing  26 . Ultimately, the driveshaft  50  is coupled with the bevel gear  24  to provide rotation to the drive hub  34 . 
     The drive hub wings  48  are separated by openings that receive the wings  56  from the cover  42  to form the cylindrical housing. 
     An inner body surface  58  is formed on the body  44  between the wings  48  (see  FIG. 9 ). The surface  58  provides a cutout to receive the cam plate  66  of the stroke adjustment mechanism  40 . Also, the inner surface  58  includes a plurality of detent bores  60 . Two detent bores  60  are shown, however depending upon the number of positions of the adjustable stroke device  30 , more bores may be included. The detent bores  60  receive detent pins  62 . The function of the detent pins  62  will be explained later. 
     The stroke adjustment mechanism  40  includes a ring  64  and a cam  66 . The ring  64  is positioned around the drive hub  34  and cover  42  as illustrated in  FIG. 1 . The ring  64  includes a cam plate  66  directly secured to the ring  64 . The cam plate  66  includes cam slots  68  and detent holes  69 . The ring  64  is manually manipulated, rotated, by the user to move the adjustable stroker device  30  between operating positions. Also, a shaft  70  extends from the cam plate  66 . The shaft  65  fits in a bore  45  in the body  44 . This enables rotation of the stroke adjustment mechanism  40  and the drive hub  34 . The cam plate  66  secures the stroke adjustment mechanism  40  with the drive hub  34 . Generally, this is accomplished via a C-clip. 
     The workpiece mounting assembly  36  includes a bearing carriage  72  and a U-shaped body portion  74 . The bearing carriage  72  receives bearing  76  and a spindle  78 . The spindle  78  extends through the bearings and bearing carriage  72 . It has an external portion  80  that includes a threaded bore  81  to receive a backing plate  82  and fastener  83 . The adjustment workpiece mounting assembly  36  also includes a locking gear  86 . The locking gear  86  engages the counterbalance mechanism  38  to lock the workpiece mounting assembly  36  in a pure rotation position. 
     The U-shaped body portion  74  includes a pin  88 . The pin  88  is received in one of the cam slots  68 . Thus, the workpiece mounting assembly  34  is moved with respect to the counterbalance mechanism  38  upon rotation of the stroke adjustment mechanism  40 . 
     The counterbalance mechanism  38  includes a body  90  with a plurality of step portions  92 . The body  90  has an overall ring shape with an elliptical configuration. The inner surface of the body  90  includes a plurality of teeth  94 . The teeth  94  engage with the locking gear  86  as mentioned above to position the adjustable stroke device  30  in a purely rotational position. One of the steps  92  include a pin  98  that is positioned in one of the cam slots  68 . The pin  98  is positioned in the slot  68  opposite of the workpiece mounting assembly pin  88 . Thus, as the stroke adjuster ring  64  is rotated, the counterbalance mechanism  38  and the workpiece mounting assembly  36  are moved away or towards one another. In the purely rotation position, the lock gear  86  engages the teeth  94  as illustrated in  FIG. 5A . 
     The cover  42  includes a base  100  that covers the bottom of the stroke adjuster  30 . The spindle portion  80  extends through the cover base opening  102  to enable connection with the backing plate  84 . The cover wings  56  insert in the openings between the drive hub wings  48 . This provides a substantially continuous cylindrical housing. The cover  42  is secured to the drive hub  34  via screws  104 . Thus, the counterbalance mechanism  38  as well as the workpiece mounting assembly  36  are positioned inside of the cover  42  and drive hub  34  housing. 
     Turning to  FIG. 6 , the detent pins  62  are illustrated. The detent pins  62  are received in the cam plate holes  69  locking the stroke adjustment mechanism  40  in a rotary mode position or in a dual action mode position. A biasing member is positioned in the bore  60  so that upon rotation of the stroke adjustment mechanism  40 , the cam plate  66  can move over the detent pin  62  into the next position where the detent pin  62  is received in another detent hole  69 . 
     Also, as can be seen in  FIGS. 6A and 6B , the cam plate  66  is positioned on the inner surface  58  of the hub body  44  defined by the cutout. The cam plate  66  rotates on the surface between positions. 
     In operation, the stroke adjustment mechanism  40  ring  64  is rotated. As this occurs, the detent pins  62  are biased away from the cam plate  66  releasing the cam plate  66  from the detent pins  62 . The ring  64  continues to turn or rotate until the detent pin  62  engages the next detent hole  69  in the cam plate  66 . As this occurs, the adjustable stroke device  30  is locked into a position. The positions move from a purely rotational position to a dual action position. 
     As the ring  64  is rotated, the pins  88 ,  98  in the slots  66  are moved. As this occurs, the workpiece mounting assembly  36  and counterbalance mechanism  38  are moved either toward one another or away from one another. In a rotary only position, the workpiece mounting assembly locking gear  86  engages the teeth  94  of the counterbalance mechanism  38 . This provides rotational only movement. As the workpiece mounting assembly  36  and counterbalance  38  mechanisms are moved away from one another, the workpiece mounting assembly  36  freely rotates in the counterweight  38  and housing providing the dual action rotary and orbital movement. 
     Accordingly, the activation switch  16  energizes the motor which rotates the spindle  50  which, in turn, rotates the drive hub  34 . This enables the backing plate  84  to be rotated with the counterbalance mechanism  38  balancing the rotational imbalance due to the spindle  78  being offset from the central axis of the spindle  50 . Thus, the spindle  78  rotates the workpiece backing plate  84  at a stroke away from the central axis. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.