Abstract:
A device and method are provided for inspecting an eccentric bushing having interior and exterior surfaces. The device includes a fixed roller and a pair of movable rollers disposed in a triangular configuration. The eccentric roller is disposed between the fixable roller and the movable rollers such that the fixed roller is disposed against an interior surface of the bushing and the movable rollers are disposed against the exterior surface of the bushing. A contact element of a gauge is disposed between the movable rollers and against the exterior surface of the bushing. Rotation of the eccentric bushing moves the contact element, which causes a display of the gauge to provide readings showing changes in the distance between the interior and exterior surfaces of the bushing.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed toward the inspection of eccentric bushings and, more particularly, toward inspection devices and methods for checking an eccentric bushing to determine the amount and direction of the offset of the eccentric bushing. 
   As is well known, an eccentric bushing is a bushing having a cylindrical exterior surface and a cylindrical interior bore, wherein the axis of the interior bore is not coaxial with the axis of the cylinder defined by the exterior surface, i.e., the axis of the interior bore is offset from the axis of the exterior surface. Eccentric bushings are used in various applications, including automotive applications. In some of these applications, it is necessary to determine the amount and/or direction of the offset of the axis of the interior bore from the axis of the exterior surface. One method that has been used to make this determination utilizes a cylindrical mount and a dial test indicator, wherein the mount is held by a metal holding device, such as a vice, and the dial test indicator is mounted to the holding device using a magnetic base. The eccentric bushing is disposed over the mount and a pivotable actuator rod of the dial test indicator is disposed against an exterior surface of the bushing. The eccentric bushing is then rotated around the mount, i.e., around the axis of the interior bore. Since the axis of the exterior surface is not coaxial with the axis of the interior bore, the exterior surface will pivot the actuator rod as the eccentric bushing is rotated. This pivotal movement of the actuator rod is amplified and displayed by a gauge of the dial test indicator. Using readings from the gauge, the amount and/or direction of the offset of the axis of the interior bore can be determined. 
   The foregoing prior art apparatus and method for inspecting eccentric bushings has several disadvantages. If the exterior surface is not perfectly cylindrical, inaccuracies are introduced into the readings. In addition, in order to permit the eccentric bushing to be rotated, there must sufficient clearance between the eccentric bushing and the mount. This clearance, however, permits the axis of the interior bore to shift, which also introduces inaccuracies into the readings. Accordingly, it is desirable to minimize the clearance between the eccentric bushing and the mount, which requires the mount to have a diameter specifically tailored for the interior bore of the eccentric bushing. Thus, multiple mounts must be provided in order to inspect eccentric bushings having interior bores with different dimensions, and even with these multiple mounts, the clearances (and, thus, the inaccuracies) cannot be totally eliminated. 
   Therefore, there exists a need in the art for an improved inspection device and method for checking an eccentric bushing, wherein the inspection device and the method can be used with eccentric bushings having interior bores with different diameters and exterior surfaces that are not perfectly cylindrical. The present invention is directed to such an inspection device and method. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, a device for inspecting an eccentric bushing having interior and exterior surfaces is provided. The device includes first, second and third holding devices, a base to which the first holding device is mounted and a carrier structure to which the second and third holding devices are mounted. The carrier structure is mounted to the base for movement relative to the base between a first position, wherein the second and third holding devices are disposed distal to the first holding device, and a second position, wherein the second and third holding devices are disposed proximate to the first holding device. A spring is disposed between the carrier structure and the base and is operable to bias the carrier structure toward the second position. A gauge is mounted to the base and includes a display and a movable contact element disposed between the second and third holding devices. The display is operatively connected to the contact element so as to provide a visual reading indicating the amount of movement of the contact element. The contact element is biased toward the first holding device. The first, second and third holding devices and the contact element are positioned to allow the eccentric bushing to be placed in an inspection position, wherein the eccentric bushing is disposed between the first holding device and the second and third holding devices, such that the first holding device is disposed against the interior surface of the eccentric bushing and such that the contact element and the second and third holding devices are disposed against the exterior surface of the eccentric bushing. When the eccentric bushing is in the inspection position, rotation of the eccentric bushing moves the contact element, which causes the display to provide readings showing changes in the distance between the interior and exterior surfaces of the eccentric bushing as the eccentric bushing is rotated. 
   Also provided in accordance with the present invention is a method of inspecting an eccentric bushing having interior and exterior surfaces. In accordance with the method a contact element and first, second and third rollers are provided. The first roller is held such that the first roller is rotatable around a first central axis and such that the first central axis is fixed in position. The second and third rollers are held such that the second and third rollers are rotatable around second and third central axes, respectively, and such that the second and third central axes are fixed in position relative to each other, but are movable relative to the first central axis in a direction perpendicular to the first central axis, and such that the first, second and third central axes are arranged in a triangular configuration. The contact element is held so as to be movable along a linear path extending between the second and third rollers. The eccentric bushing is placed between the first roller and the second and third rollers, such that the first roller is disposed against the interior surface of the eccentric bushing and such that the contact element and the second and third rollers are disposed against the exterior surface of the eccentric bushing. Biasing forces are applied to the contact element and the second and third rollers that urge the contact element and the second and third rollers toward the first roller. The eccentric bushing is rotated while being positioned between the first roller and the second and third rollers, which causes the contact element to move. This movement is measured to provide a measure of the changes in distance between the interior and exterior surfaces of the eccentric bushing as the eccentric bushing is rotated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
       FIG. 1  is a top perspective view of an inspection device being used to check an eccentric bushing; and 
       FIG. 2  is an exploded view of the inspection device. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   It should be noted that in the detailed description that follows, identical components have the same reference numerals, regardless of whether they are shown in different embodiments of the present invention. It should also be noted that in order to clearly and concisely disclose the present invention, the drawings may not necessarily be to scale and certain features of the invention may be shown in somewhat schematic form. 
   As used herein, the term “eccentric bushing” shall mean a bushing having a cylindrical exterior surface and a cylindrical interior bore, wherein the axis of the interior bore is not coaxial with the axis of the cylinder defined by the exterior surface, i.e., the axis of the interior bore is offset from the axis of the exterior surface. 
   As used herein with regard to an eccentric bushing, the term “high point” shall mean the location on an exterior surface of the eccentric bushing, wherein the distance between the exterior surface and an interior surface of the eccentric bushing is greatest. In other words, the high point is positioned opposite the direction of the offset. 
   The present invention is directed to an inspection device for checking an eccentric bushing to determine the amount and direction of the offset of the eccentric bushing and, in connection therewith, to determine the “high point” of the eccentric bushing. 
   Referring now to  FIGS. 1 and 2 , the inspection device  10  generally comprises a base  12 , a carrier structure  14 , a first holding device or roller assembly  16 , a second holding device or roller assembly  18 , a third holding device or roller assembly  20 , a gauge  22  and a lever assembly  24 . As will be discussed more fully below, the base  12  and the carrier structure  14  cooperate to form a holding structure to which the first, second and third roller assemblies  16 ,  18  and  20  are mounted. 
   The base  12  is preferably composed of a metal, such as aluminum or more preferably steel, and includes a mount  28  joined to a top surface of a support structure  30 . The support structure  30  has first and second ends  30   a ,  30   b  and is substantially rectangular in shape, except for a cut-out region  32  at the second end  30   b , which is defined by inward side and end surfaces  34 ,  36 . A smooth bore  38  and a threaded bore  40  extend into the inward side surface  34 . The mount  28  is L-shaped and includes a foot portion  28   a  joined at a right angle to an elongated body portion  28   b . An end surface of the foot portion  28   a  extends along and is preferably aligned with the first end  30   a  of the support structure  30 . A horizontal main bore (not shown) extends transversely through the foot portion  28   a  and longitudinally through a major portion of the body portion  28   b  of the mount  28 . The main bore has an opening formed in the end surface of the foot portion  28   a . A horizontal side bore (not shown) extends through the foot portion  28   a  and intersects the main bore at a right angle. At least an outer portion of the side bore is threaded. An opening for the side bore extends through a side surface of the foot portion  28   a . A vertical first mounting bore  42  is formed in the body portion  28   b  of the mount  28 . The first mounting bore  42  is threaded and is located proximate to a free end of the body portion  28   a , which is disposed toward the second end  30   b  of the support structure  30 . 
   The carrier structure  14  is also preferably composed of a metal, such as aluminum or more preferably steel. The carrier structure  14  is generally C-shaped and includes a pair of spaced-apart first and second arms  46 ,  48  joined together by an enlarged bridge portion  50 . Vertical second and third mounting bores  52 ,  54  are formed in the first and second arms  46 ,  48 , respectively. The second and third mounting bores  52 ,  54  are threaded and are located proximate to free ends of the first and second arms  46 ,  48 , respectively. A horizontal spring bore  56  extends longitudinally through the bridge portion  50 . The spring bore  56  extends between an inner opening in an interior end surface of the bridge portion  50 , which is disposed between the first and second arms  46 ,  48 , and an outer opening in an opposing end surface  50   a  of the bridge portion  50 , which is disposed distal to the first and second arms  46 ,  48 . The spring bore  56  is threaded at least toward the outer opening. A spring  58  is disposed in the spring bore  56  and includes an inner end, which extends out from the interior end surface (when the spring  58  is relaxed), and an outer end, which is disposed against a set screw  62  that is threaded into the spring bore  56  through the outer opening. 
   The first, second and third roller assemblies  16 ,  18 ,  20  each include a hollow cylindrical roller  64  disposed around and rotatably secured to a center axle  66 . Each of the center axles  66  includes a threaded body joined to a head, which is disposed within the opening of its associated roller  64 . The center axles  66  of the second and third roller assemblies  18 ,  20  are threadably secured within the second and third mounting bores  52 ,  54  of the carrier structure  14 , respectively, thereby mounting the second and third roller assemblies  18 ,  20  to the first and second arms  46 ,  48 , respectively. As will be discussed further below, the center axle  66  of the first roller assembly  16  is threadably secured within the first mounting bore  42  of the base  12 . 
   The roller  64  of the first roller assembly  16  has a diameter that is larger than the distance between the rollers  64  of the mounted second and third roller assemblies  18 ,  20  and that is preferably larger than the distance between the first and second arms  46 ,  48  of the carrier structure  14 . Preferably, the rollers  64  of the first, second and third roller assemblies  16 - 20  have the same, or substantially the same, diameters. 
   The gauge  22  includes a housing  70  having a cylindrical side wall  72  and a rear or bottom end wall. A graduated dial face  74  enclosed in a glass casing is secured over an open front or top end of the housing  70 . The dial face  74  is provided with a graduated scale around its circumference, such as from 0 to 100 for half the circumference and 0 to −100 for the other half of the circumference. An elongated mounting rod  78  is secured to the housing  70  so as to extend in cantilever fashion therefrom. The mounting rod  78  is a half cylinder and includes a planar inner surface and an arcuate outer surface. An end of the mounting rod  78  is fixedly secured within an opening of an anchor eyelet  80  that is secured to the bottom end wall. A hollow cylindrical tube  82  passes through the side wall  72  of the housing  70  and extends parallel to the mounting rod  78 . An actuator rod  84  is slidably disposed in the tube  82  and extends outwardly therefrom. A contact pad or element  86  is secured to an exterior end of the actuator rod  84 . The contact element  86  preferably has a rounded contact surface. The actuator rod  84  is movable between retracted and extended positions. A spring (not shown) biases the actuator rod  84  toward the extended position. An interior end of the actuator rod  84  is connected by a linkage (not shown) to a shaft  88  that extends through the dial face  74 . A pointer  90  is secured to an outer end of the shaft  88 . The linkage is operable to translate linear movement of the actuator rod  84  to angular or rotational movement of the shaft  88  and, thus, the pointer  90 . This translation is preferably amplified so that a small linear movement of the actuator rod  84  causes a relatively large rotational movement of the pointer  90 . A calibration knob  92  is provided for calibrating the gauge  22 , i.e., to locate the pointer  90  at a zero graduation for a given position of the actuator rod  84 . 
   The gauge  22  is mounted to the base  12  by the mounting rod  78  and a locking mechanism  96 . More specifically, the mounting rod  78  is inserted into the main bore of the mount  28  so as to be slidable therein between extended and retracted positions. The planar inner surface of the mounting rod  78  faces the locking mechanism  96 . The locking mechanism  96  is operable to lock the mounting rod  78  in a fixed position within the main bore. The locking mechanism  96  includes a knurled knob  98  secured to a base cylinder  100  having a thread formed therein. An elongated contact rod  102  extends from the base cylinder  100  and is fixedly secured thereto. The contact rod  102  and at least a portion of the base  12  are disposed in the side bore. Threads of the base cylinder  100  are engaged with threads defining the outer portion of the side bore so as to threadably secure the locking mechanism  96  to the base  12 . Rotation of the knob  98  in a tightening direction causes the threads of the base cylinder  100  to move along the threads of the side bore such that the base cylinder  100  and, thus, the contact rod  102 , move laterally inward until a free end of the contact rod  102  is pressed against the planar inner surface of the mounting rod  78 , which secures the mounting rod  78  in its current position and prevents further lateral movement of the contact rod  102 . At this point, the locking mechanism  96  is in a locked mode. Rotation of the knob  98  in a loosening direction causes the threads of the base cylinder  100  to move along the threads of the side bore such that the base  12  and, thus, the contact rod  102 , move laterally outward so as to move the free end of the contact rod  102  away from the mounting rod  78 , which permits the mounting rod  78  to move within the main bore. At this point, the locking mechanism  96  is in a released mode. 
   The carrier structure  14  is disposed over the base  12  such that a bottom surface of the carrier structure  14  is supported on a top surface of the support structure  30  of the base  12  and such that the free end of the body portion  28   b  of the mount  28  is disposed between the first and second arms  46 ,  48  of the carrier structure  14 . With the carrier structure  14  and the body portion  28   b  so positioned, the body of the center axle  66  of the first roller assembly  16  is threaded into the first mounting bore  42  in the body portion  28   b  of the mount  28 , thereby positioning at least a majority of the roller  64  between the first and second arms  46 ,  48  of the carrier structure  14 . An annular retaining washer  106  is preferably disposed around the body of the center axle  66  before the body is threaded into the first mounting bore  42 . The retaining washer  106  has a diameter larger than the distance between the first and second arms  46 ,  48  and larger than the diameter of the roller  64 . The retaining washer  106  includes a central opening, through which the body extends, and which has a diameter smaller than the diameter of the roller  64 . In this manner, the retaining washer  106  is trapped between the roller  64  and the carrier structure  14 . Since the diameter of the retaining washer  106  is larger than the distance between the first and second arms  46 ,  48  of the carrier structure  14 , the carrier structure  14  is vertically trapped between the base  12  and the retaining washer  106 , thereby preventing the carrier structure  14  from being separated from the base  12  in a vertical direction. 
   Since the roller  64  of the first roller assembly  16  has a diameter larger than the distance between the rollers  64  of the mounted second and third roller assemblies  18 ,  20 , the rollers  64  of the second and third roller assemblies  18 ,  20  cannot be moved past the roller  64  of the first roller assembly  16  when the carrier structure  14  is moved toward the second end  30   b  of the support structure  30 . Movement of the carrier structure  14  toward the first end  30   a  of the support structure  30  is limited by contact between the interior end surface of the bridge portion  50  and the free end of the body portion  28   b  of the mount  28 . Thus, the carrier structure  14  is movable between a first position, wherein the interior end surface of the bridge portion  50  of the carrier structure  14  contacts the free end of the body portion  28   b  of the mount  28 , and a second position, wherein the rollers  64  of the second and third roller assemblies  18 ,  20  contact the roller  64  of the first roller assembly  16 . As can be appreciated, the foregoing restrictions in the movement of the carrier structure  14  prevents the carrier structure  14  from being separated from the base  12  in a horizontal direction. 
   With the carrier structure  14  mounted to the base  12  in the foregoing described manner, the outer end of the spring  58  is disposed against the free end of the body portion  28   b  of the mount  28 . The spring  58  is at least partially compressed and biases the carrier structure  14  toward the second position. The set screw  62  may be threadably moved inwardly to increase the compression and, thus, the biasing force of the spring  58 , or outwardly to reduce the compression and, thus, the biasing force of the spring  58 . 
   The carrier structure  14  is movable by the lever assembly  24 , which includes an elongated lever  110 , a limit pin  112  and a contact device  114 . 
   The lever  110  has an upper handle portion  116  and a lower mounting portion  118  with arcuate first and second protruding regions  118   a ,  118   b . First and second holes  120 ,  122  are formed in the first and second protruding regions  118   a ,  118   b , respectively. 
   The contact device  114  includes a hollow cylindrical roller  124  rotatably secured to a center axle  126 , which includes a threaded body joined to a head. The contact device  114  is mounted to the mounting portion  118  of the lever  110 . More specifically, the body of the center axle  126  extends through the second hole  122  of the mounting portion  118  and has a fastening nut  128  threaded thereto, on a side of the lever  110 , opposite to the head of the center axle  126 . 
   The limit pin  112  is disposed in the smooth bore  38  of the support structure  30  and extends laterally outward therefrom. The limit pin  112  is secured in the smooth bore  38 , such as by a friction fit. 
   The lever  110  is pivotally mounted to the support structure  30  of the base  12  by a shoulder screw  130  having a body that extends through the first hole  120  in the mounting portion  118  and is threadably received in the threaded bore  40  of the support structure  30 . The mounting portion  118  of the lever  110  is located between the limit pin  112  and the inward end surface  36  of the support structure  30 . The lever  110  is pivotal between an actuated position and a neutral position to move the carrier structure  14  between the first and second positions. When the lever  110  is in the neutral position, the roller  124  of the contact device  114  rests against the limit pin  112 , with the handle portion  116  of the lever  110  extending upwardly and rearwardly. When the handle portion  116  is moved forwardly by the hand of an operator, the lever  110  pivots from the neutral position toward the actuated position. As the lever  110  pivots forwardly, the roller  124  of the contact device  114  contacts the end surface  50   a  of the carrier structure  14  and applies a forwardly-directed force to the carrier structure  14 , thereby causing the carrier structure to move toward the first position. When the carrier structure  14  reaches the first position, further pivotal movement of the lever  110  is prevented and the lever  110  is disposed in the actuated position. When the operator moves the lever  110  back to the neutral position and/or releases the handle portion  116 , the bias of the spring  58  causes the carrier structure  14  to move back to the second position. 
   When the inspection device  10  is not holding an eccentric bushing, the inspection device  10  is in a neutral mode, wherein the carrier structure  14  is horizontally disposed in the second position, with the rollers  64  of the second and third roller assemblies  18 ,  20  in contact with the roller  64  of the first roller assembly  16 . The contact element  86  is disposed against or proximate to the roller  64  of the first roller assembly  16  and the pointer  90  of the gauge  22  is located at the zero graduation. 
   The inspection device  10  is operable to inspect eccentric bushings, such as the eccentric bushing shown in  FIG. 1 , which is designated by the reference numeral  136 . The eccentric bushing  136  has a cylindrical outer surface  138  and an inner surface  140  defining a cylindrical interior bore  142 . The outer surface  138  defines a cylinder having an axis that is not coaxial with an axis of the interior bore  142 . In other words, the axis of the interior bore  142  is offset from the axis of the outer surface  138 . 
   The eccentric bushing  136  is loaded or inserted into the inspection device  10  by first moving the carrier structure  14  to the first position using the lever  110  and moving the contact element  86  away from the first roller assembly  16 . The eccentric bushing  136  is then disposed over the first roller assembly  16  such that the roller  64  thereof is disposed against the inner surface  140  of the eccentric bushing  136 . Once the eccentric bushing  136  is so disposed, the carrier structure  14  is allowed to move back toward the second position and the contact element  86  is allowed to move toward the first roller assembler  16 . The presence of the eccentric bushing  136  maintains the contact element  86  and the second and third roller assemblies  18 ,  20  in outward positions (i.e., positions located toward the first end  30   a  of the support structure  30 ) relative to the positions they occupy when the inspective device  10  in the neutral mode. 
   With the eccentric bushing  136  positioned in the above-described manner, the eccentric bushing  136  is disposed between the first roller assembly  16  and the second and third roller assemblies  18 ,  20 , as shown in FIG.  1 . More specifically, the roller  64  of the first roller assembly  16  is disposed against the inner surface  140  of the eccentric bushing  136 , while the rollers  64  of the second and third roller assemblies  18 ,  20  are disposed against the outer surface  138  of the eccentric bushing  136 . The contact element  86  is disposed between the second and third roller assemblies  18 ,  20  and is pressed against the outer surface  138  of the eccentric bushing  136 . The pointer  90  of the gauge  22  is located at a graduation having a value that provides a measure of the distance between the outer surface  138  and the inner surface  140  of the eccentric bushing  136  at the location of the contact element  86 . 
   After the eccentric bushing  136  has been loaded into the inspection device  10  and is positioned as described above, the eccentric bushing  136  is rotated by hand. As the eccentric bushing  136  is rotated, the roller  64  of the first roller assembly  16  and the rollers  64  of the second and third roller assemblies  18 ,  20  maintain contact with the inner and outer surfaces  140 ,  138  of the eccentric bushing  136 , respectfully, due to the biasing action of the spring  58 . Similarly, the contact element  86  maintains contact with the outer surface  138  of the eccentric bushing  136  due to the biasing action of the gauge spring on the actuator rod  84 . Since the rollers  64  are rotatable and may rotate along with the eccentric bushing  136 , the frictional resistance between the rollers  64  and the eccentric bushing  136  is reduced. As the eccentric bushing  136  is rotated, the distance between the outer surface  138  and the inner surface  140  of the eccentric bushing  136  at the contact element  86  changes due to the offset between the axis of the interior bore  142  and the axis of the cylinder defined by the outer surface  138 . This change in distance between the outer and inner surfaces  138 ,  140  moves the contact element  86 , which, in turn, moves the pointer  90 . More specifically, as the distance between the outer and inner surfaces  138 ,  140  increases, the readings of the pointer  90  increase, and as the distance between the outer and inner surfaces  138 ,  140  decreases, the readings of the pointer  90  decrease. In this manner, the highpoint of the eccentric bushing  136  may be determined by simply rotating the eccentric bushing  136  until the pointer  90  is positioned at a graduation having a maximum value (for a revolution of the eccentric bushing  136 ). When this reading occurs, the highpoint of the eccentric bushing  136  will be disposed against the contact element  86 . 
   After the eccentric bushing  136  has been inspected, the eccentric bushing  136  is removed from the inspection device  10  by first moving the carrier structure  14  to the first position using the lever  110  and, while the carrier structure  14  is in the first position, removing the eccentric bushing  136  from between the first roller assembly  16  and the second and third roller assemblies  18 ,  20 . Another eccentric bushing may then be inserted into the inspection device  10  for inspection. If the subsequent eccentric bushing has different dimensions than the eccentric bushing  136 , the gauge  22  may be moved inward or outward, as required, to properly position the contact element  86  relative to the subsequent eccentric bushing. This movement of the gauge  22  is accomplished by first rotating the knob  98  to move the locking mechanism  96  to the released mode. An inward or outward force, as required, is applied to the housing  70 , which causes the mounting rod  78  to slide through the main bore of the mount  28  and the housing  70  to move inward or outward, as the case may be, relative to the base  12 . When the contact element  86  is properly positioned, the knob  98  is then rotated to move the locking mechanism  96  to the locked mode. The subsequent eccentric bushing may then be inserted into the inspection device  10  in the same manner as the eccentric bushing  136 . 
   While the invention has been shown and described with respect to particular embodiments thereof, those embodiments are for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein described will be apparent to those skilled in the art, all within the intended spirit and scope of the invention. Accordingly, the invention is not to be limited in scope and effect to the specific embodiments herein described, nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.