Abstract:
An actuator linkage for imparting a rotating motion to a clutch operating shaft according to one embodiment of the present invention comprises a linear actuator including an extendable and retractable arm, the arm including a pivot end, a linkage bar having a first pivot location and an oppositely-disposed second pivot location, a slotted linkage bar having a first pivot location and an oppositely-disposed second pivot location having the shape of a slot, a control link having a first end constructed and arranged to connect to the control shaft and a second end defining a pivot location, wherein the pivot end of the extendable and retractable arm, the first pivot location of the linkage bar, and the first pivot location of the slotted linkage are pivotally connected together, and the control link being constructed and arranged to move from a first slack position through a clutch operating shaft over-center position to a second slack position with movement of the extendable and retractable arm.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates in general to clutch actuators that are used to engage and disengage a clutch that is associated with an engine. More specifically, the present invention relates to a clutch actuator linkage that is used in cooperation with a clutch that is operably connected to an engine. The clutch includes a clutch operating shaft that cooperates with the clutch actuator linkage so as to transition the clutch from a disengaged condition to an engaged condition and then return from an engaged condition to a disengaged condition. 
         [0002]    In a broad, conceptual sense, clutches are considered to be well known mechanisms. While the engaging and disengaging configurations or mechanisms can assume a variety of forms and constructions, clutches (generally) are constructed and arranged for use in conjunction with two rotating shafts such as a motor vehicle engine and its manual transmission. Clutches are also found in other devices, such as cordless drills and chain saws, as only a couple of other examples. 
         [0003]    A typical clutch configuration connects the two shafts so that they can either be locked together and rotate at the same speed or de-coupled and rotate at different speeds. In a motor vehicle, depressing the clutch pedal disengages the clutch from the engine. In other clutch designs, the engaging and disengaging mechanism and method may be different. For example, a clutch may be engaged and disengaged by the use of a hand lever connected to one end of an operating shaft. Turning or rotating the clutch operating shaft about its longitudinal axis turns a throw out yoke for the desired engagement with other portions of the clutch structure. A representative example of such a construction is offered by Arrow Engine Company of Tulsa, Okla. by its clutch model No. C-110-HP-3. This type of clutch actuator would be compatible for engaging a clutch on any engine utilizing a power take off (PTO) type clutch where it is necessary to use linear motion to engage or disengage a clutch mechanism. A good example of this application would be the C-Series engine also offered by Arrow Engine Company. These gas engines are constructed and arranged for continuous duty use in oil fields for powering a pump jack, as one example. Since these types of engines and clutches do not lend themselves to incorporation of a clutch pedal, the referenced hand lever has been provided. However, use of the hand lever requires a human presence and considering the size and location of the clutch and engine, an automated linkage to actuate the clutch (i.e., engage and disengage) is seen as an improvement. 
         [0004]    One type of automated device for a clutch linkage is offered by F. W. Murphy (United Kingdom) with its U.S. facility in Tulsa, Okla., as model No. CO3. The CO3 product is described as an “electric motor driven clutch operator for engine automation systems”. This electronic controlled and driven design requires various component controls such as limit switches, or the like, in order to control the travel of linkage and/or clutch components. 
         [0005]    The disclosed structure, as presented herein, approaches the automated actuator design in a manner that is different from the F. W. Murphy CO3. The structure disclosed herein uses a linear actuator and a unique linkage to turn the clutch operating shaft. By taking advantage of the over-center clutch design in terms of its operating shaft, the disclosed structure is able to substantially eliminate any noticeable clutch pre-load that might otherwise be applied to the clutch operating shaft according to various prior art designs. Importantly, the clutch that is associated with the disclosed clutch linkage, as described herein, has a structural configuration that incorporates an over-center position between the clutch-disengaged position and the clutch-engaged position. The force requirements to rotate or turn the clutch operating shaft increase as the clutch operating shaft approaches that over-center position. When the clutch operating shaft snaps or pops through this over-center position, the clutch is engaged and no further force is required to maintain the clutch-engaged position by means of the clutch operating shaft and the disclosed actuator linkage. 
       BRIEF SUMMARY 
       [0006]    An actuator linkage for imparting a rotating motion to a control shaft according to one embodiment of the present invention comprises a linear actuator including an extendable and retractable arm, the arm including a pivot end, a linkage bar having a first pivot location and an oppositely-disposed second pivot location, a slotted linkage bar having a first pivot location and an oppositely-disposed second pivot location having the shape of a slot, a control link having a first end constructed and arranged to connect to the control shaft and a second end defining a pivot location, wherein the pivot end of the extendable and retractable arm, the first pivot location of the linkage bar, and the first pivot location of the slotted linkage are pivotally connected together, and the control link being constructed and arranged to move from a first slack position through a control shaft over-center position to a second slack position with movement of the extendable and retractable arm. 
         [0007]    One object of the present disclosure is to describe an improved actuator linkage. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of an actuator linkage in combination with a clutch and engine according to a typical embodiment. 
           [0009]      FIG. 2  is a side elevational view of the  FIG. 1  combination. 
           [0010]      FIG. 3  is a rear elevational view of the  FIG. 1  combination. 
           [0011]      FIG. 4  is a top plan view of the  FIG. 1  combination. 
           [0012]      FIG. 5  is an exploded, side elevational view, of the  FIG. 1  actuator linkage. 
           [0013]      FIG. 6  is an exploded, perspective view, of the  FIG. 1  actuator linkage. 
           [0014]      FIG. 7  is a side elevational view of the  FIG. 1  combination with the clutch and actuator linkage in a disengaged position. 
           [0015]      FIG. 7A  is a diagrammatic illustration of a pivot pin placement relative to a slot of the  FIG. 1  actuator linkage. 
           [0016]      FIG. 8  is a side elevational view of the  FIG. 1  combination with the clutch and actuator linkage in an engaged position. 
           [0017]      FIG. 8A  is a diagrammatic illustration of the pivot pin placement in the slot. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    For the purposes of promoting an understanding of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated device and its use, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates. 
         [0019]    Referring to  FIGS. 1-4 , there is illustrated the assembled combination of an engine  20 , clutch  21 , clutch operating shaft  22 , and clutch actuator assembly  23  that is constructed and arranged according to the disclosed embodiment of the present invention. As is well known in the art, the clutch  21  is operably coupled to the engine  20  and the clutch  21  is engaged and disengaged by turning or rotation of a control shaft, described herein as a clutch operating shaft  22 . The direction of turning or rotation is about the longitudinal axis of the shaft  22 . The focus of the present disclosure is on clutch actuator assembly  23  and its included linkage. Further, while clutch actuator assembly  23  is disclosed in combination with a clutch  21  and engine  20 , the actuator assembly has broader applicability and can be used for other types of mechanisms or devices where turning or rotation of a control shaft or similar structure is desired. Preferably, these other or alternative uses for similar or related structures also include the use of an over-center position so as to result in a slack condition for the linkage and thereby eliminate any clutch (or other device) pre-load as being applied at or on the clutch operating shaft when the clutch is either fully engaged or fully disengaged. As used herein, “slack condition” refers to the linkage slot and the pin being generally centered in the slot. The representation of clutch actuator assembly  23  in the context environment of the illustrated engine  20  and clutch  21  combination is considered to be the preferred embodiment and best mode, as far as the overall assembly. However, it is not intended that the scope of this disclosure nor the use of actuator assembly  23  be limited to what is specifically illustrated. It is also important to understand that clutch  21 , as briefly described in the Background, includes an over-center or cross-over construction causing the clutch operating shaft to pop past the over-center location into a no-load or no-force status. 
         [0020]    With continued reference to  FIGS. 1-4 , clutch  21  is constructed and arranged in a generally conventional manner incorporating a drive ring, series of plates, and a clutch shaft, among other component parts. A representative clutch is a model No. C-110-HP-3 offered by Arrow Engine Company of Tulsa, Okla. Although separately identified and numbered, clutch operating shaft  22  is a part of clutch  21 . Shaft  22  is splined and is received within the cooperating and compatible splined linkage bar  26 . As can be seen in  FIGS. 3 and 4 , shaft  22  extends through the clutch housing  27 . 
         [0021]    The turning or rotation of clutch operating shaft  22  about its longitudinal axis, in a counterclockwise direction, based upon the side elevational view and orientation of  FIG. 2 , is required in order to engage the clutch, beginning from a clutch-disengaged condition. As has been described, the clutch  21  and its associated components operate with an over-center construction. This means that when turning the clutch operating shaft  22  for clutch  21  engagement, the force required increases as the over-center location or condition is approached. When the clutch operating shaft  22  travels through the over-center position, the clutch is engaged and the clutch operating shaft  22  exhibits a continuously reduced input force as it crosses through this cross-over point and then the clutch actuator assembly  23  generally assumes a slack condition such that no continuing force is required to be applied to the clutch operating shaft in order to maintain clutch engagement. This can also be described as having eliminated any clutch pre-load that would be applied at the clutch operating shaft when the clutch is fully engaged (or fully disengaged). 
         [0022]    In the reverse direction, moving from the clutch-engaged condition to the clutch-disengaged condition, the clutch operating shaft is turned in a clockwise direction, based upon the  FIG. 2  orientation. During this return path for the clutch operating shaft, the over-center position or location is once again encountered. The force required for the clutch operating shaft to rotate through that over-center position increases as the over-center position is approached and is at a maximum at the over-center position. As the over-center position is passed, the clutch operating shaft pops free as no input force is required for the clutch operating shaft and causes the dependent movement of the splined linkage bar  26  in a clockwise direction, based on the  FIG. 2  orientation. 
         [0023]    Referring now to  FIGS. 5 and 6 , exploded views of clutch actuator assembly  23  are illustrated. Clutch actuator assembly  23  includes an engine case bracket  30 , linkage bar  31 , slotted linkage bar  32 , clevis bracket  33 , linear actuator  34 , clutch housing bracket  35 , splined linkage bar  26 , and an assortment of pins in order to connect the linkage members together. The referenced “pins” can be shouldered bolts or rivets as well as headed pins, shafts, or any other material acting to mechanically connect a rotating joint. Case bracket  30  includes a pivot plate  36  jointed to a mounting plate  37 . The mounting plate includes a clearance opening  38  for use in bolting the bracket  30  to the engine case  39 . The two pivot pin holes  40   a  and  40   b  are defined by plate  36 . While only one pivot pin hole is used for any one engine/clutch combination, providing more than one hole gives added versatility to the assembly installation as different engine/clutch combinations can be accommodated. In the illustrated embodiment, the closer pivot pin hole  40   b  is used for the connection of linkage bar  31 . 
         [0024]    Clutch housing bracket  35  is constructed and arranged for attachment to clutch housing  27  by the use of threaded fasteners, preferably capscrews. Bracket  35  includes a clevis support  43  and a mounting plate  44 . The mounting plate  44  defines two clearance holes  45   a  and  45   b . These two clearance holes are sized and spaced to fit into the bolt circle  46  of the clutch housing  27 , see  FIG. 1 . Plate  44  also has an arcuate edge  47  to fit and conform to circular edge  48  of the clutch housing  27 . Upper cylindrical post  49  of linear actuator  34  fits between the flanges  43   a  and  43   b  of the clevis support  43  and a pivot pin  50  extends through each flange hole  43   c  and  43   d  and through pivot hole  51  in post  49 . Hole  51  is a single, radial through-hole passing through post  49  on a diameter. 
         [0025]    Actuator clevis bracket  33  includes a pair of spaced flanges  53  and  54  and a hollow cylindrical post  55  with two radial aligned holes through (on a diameter) with a pivot pin hole  56 . The clevis flanges  53  and  54  each define a corresponding pivot pin hole  53   a  and  54   a , respectively. Holes  53   a  and  54   a  are axially aligned with each other. Linear actuator  34  includes an extendable and retractable actuator arm  57  that is shouldered between larger and smaller diameter portions. The smaller diameter portion  58  includes a single, radial through hole  58   a . Portion  58  fits closely within the hollow interior of post  55  and hole  58   a  is aligned with pivot pin hole  56 , upon engagement. Pivot pin  59  is inserted through holes  58   a  and  56 . 
         [0026]    Linkage bar  31  includes a flat, single thickness end  62  and opposite thereto a clevis end  63  with spaced-apart clevis end flanges  63   a  and  63   b . End  62  defines a pivot pin hole  64  and each flange  63   a  and  63   b  defines a pivot pin hole  65  and  66 , respectively. Holes  65  and  66  are axially aligned with each other. Holes  64 ,  65 , and  66  are all located (i.e., centered) on the longitudinal centerline  31   a  of linkage bar  31 . 
         [0027]    Slotted linkage bar  32  includes a pivot hole end  67  and a slotted end  68 . The center of pivot pin hole  69  and the centerline of slot  70  are located (i.e., centered) on the longitudinal centerline  32   a  of slotted linkage bar  32 . End  67  is sized and arranged to fit closely between clevis flanges  63   a  and  63   b . Clevis end  63  is sized and arranged to fit closely between clevis flanges  53  and  54 . Once the pivot pin holes  53   a  and  54   a  are axially aligned with pivot pin holes  65  and  66 , and with pivot pin hole  69 , pin  71  is inserted in order to create a pivot joint for the assembled linkage. End  62  of linkage bar  31  is pinned to case bracket  30  using pin  74  inserted through hole  64  into either pivot pin hole  40   a  or pivot pin hole  40   b , depending on the installation arrangement. 
         [0028]    The splined linkage bar  26  includes a splined, hollow tube portion  78  that is constructed and arranged to engage end  79  of clutch operating shaft  22 . A right angled clevis link  80  is included in unitary construction with portion  78 . Portion  78  has an axial centerline  81  that is substantially perpendicular to the longitudinal centerline  82  of link  80 . The free end  83  of link  80  includes spaced-apart clevis flanges  84  and  85 , each flange defining a corresponding pivot pin hole  84   a  and  85   a , respectively. Holes  84   a  and  85   a  are axially aligned with each other and are located on longitudinal centerline  82 . Slotted end  68  of linkage bar  32  fits closely between flanges  84  and  85  and is pinned in that position by pivot pin  86 . The open end  90  of tube portion  78  is splined (female) and the free end  79  of shaft  22  is correspondingly splined (male). Clamping flange portion  92  and capscrew  93  are constructed and arranged for clamping open end  90  tightly around the free end  79  of shaft  22 . 
         [0029]    Referring to  FIGS. 7 and 8 , the assembled combination of engine  20 , clutch  21 , clutch operating shaft  22 , and clutch actuator assembly  23  is illustrated in the clutch disengaged condition ( FIG. 7 ) and in the clutch engaged condition ( FIG. 8 ). In terms of the operation of clutch actuator assembly  23 , we begin with the linear actuator  34  in a retracted, disengaged condition as illustrated in  FIG. 7 . In this condition, pivot pin  86  is positioned approximately in the mid-range of slot  70  between the closed ends (see FIG.  7 A). This is also described as a slack position of the slotted linkage bar  32 . Upon extension of arm  57  of the linear actuator  34 , the joint formed by the actuator clevis bracket  33 , the unslotted linkage bar  31 , and the slotted linkage bar  32  begins to move in a downward direction based upon the  FIG. 7  orientation with line  88  representing a generally horizontal plane. This manner of movement increases the magnitude of the included angle (α) between linkage bars  31  and  32 . It will be noted that these two linkage bars are pivotally connected to each other and in the starting position (disengaged condition), these two linkage bars define an included angle (α) which is (initially) less than 180°. As the actuator arm  57  extends in a downward direction, this translates into movement of linkage bars  31  and  32  and this in turn translates into rotational movement of splined linkage bar  26 . Splined linkage bar  26  functions as a moment arm, providing rotation to the splined clutch operating shaft  22 . As the clutch operating shaft rotates and approaches the clutch over-center position, the required linkage force gradually increases. When the over-center position is reached, the linkage arrangement is also at its maximum required force level in order to pop the clutch operating shaft through that over-center position. Just as the clutch operating shaft pops past the over-center position, the clutch is engaged. Once the clutch operating shaft pops through the over-center position to the counterclockwise side of that position, no further force is required in order to maintain the clutch-engaged condition. Even though the clutch is engaged at this point, an event that generally coincides with a linear relationship between linkage bars  31  and  32  (included angle (α)=180°), the linear actuator continues to extend arm  57 . As this continuing travel occurs, it causes the two linkage bars  31  and  32  to move off of their substantially co-linear alignment and causes the included angle (α) to become greater than 180°. The pivot pin  86  gradually moves toward the center of slot  70  and the linkage assembly  23  assumes the “slack position”. When the linear actuator arm  57  reaches its designed, fully extended position, the linear actuator is de-energized by the use of internal limit switches (not shown). The clutch  21  is fully engaged without any pre-load from the linkage assembly  23  and remains until the linear actuator receives a control input. 
         [0030]    In the disengaged position, pin  86  is located in the mid-range of slot  70  (see  FIG. 7A ) and this is described as a “slack” position. Then, as the arm  57  of linear actuator  34  is extended, pin  86  begins to move (slide) toward the inner closed end of slot  70 . When the travel of pin  86  stops or bottoms out at the left end of the slot  70 , continued movement of arm  57  results in the described turning or rotation of the splined clutch operating shaft  22 . When the arm  57  pushes linkage bars  31  and  32  past their co-linear position, the slotted linkage bar  32  is pulled away from the splined linkage bar  26 . This draws pin  86  into the approximate center of slot  70  (see  FIG. 8A ). While this linkage movement is occurring, the clutch operating shaft has reached the over-center location and has been forced through that location, popping to the other side and causing the engagement of the clutch. This is also a no-load condition since no continuing or constant force is required to maintain the clutch engaged condition. When the pin  86  is generally in the center of slot  70  between its closed ends, the clutch is engaged and the linkage is in a slack condition. As a result, the clutch is engaged without input force or pre-load on the clutch operating shaft. This design configuration extends the life of the clutch, the linkage, the actuator, and shaft construction used to engage the clutch. 
         [0031]    When the clutch actuator assembly  23  is moved from the clutch-engaged position of  FIG. 8  back to the clutch-disengaged position of  FIG. 7 , generally speaking the reverse sequence of those steps just described will occur. This begins with retracting arm  57  of the linear actuator  34 . As the arm  57  retracts, the linkage bars  31  and  32  move from an included angle (α) of greater than 180° to the 180° engaged point where pin  86  is at the left end of slot  70  and then on to an included angle (α) that is less than 180° where pin  86  once again moves toward the center of slot  70 . As this movement occurs, pin  86  slides in slot  70  from the described slack condition with the pin  86  midway in slot  70  to the left and then reverses to the right end of the slot. Once the pin  86  bottoms out at the right end of slot  70 , the continued retraction of arm  57  causes the clockwise rotation of splined linkage bar  26  and this rotates the clutch operating shaft  22  toward the over-center location. As the over-center location is approached, the force requirement increases. When the clutch operating shaft pops past the over-center location, it jumps, causing the splined linkage bar  26  to pivot toward a vertical position based on the  FIG. 2  orientation and positioning pin  86  in slot  70  between the closed ends of slot  70 . As the actuator  34  retracts arm  57 , pin  86  moves toward the approximate center of slot  70  (i.e., the slack position). This slack position generally corresponds to the disengaged condition of  FIG. 7 . While there is some continued movement is fully retracted, the pin  86  stays generally in the slack position and is not bottomed out on the right end of slot  70 . 
         [0032]    Configuring actuator assembly  23  in the manner described enables the engine clutch to be engaged and disengaged while eliminating any clutch pre-load applied to the clutch operating shaft when the clutch is fully engaged and when it is fully disengaged. This operation corresponds to the referenced “slack” positions of the linkage associated with the actuator assembly  23 . 
         [0033]    While the preferred embodiment of the invention has been illustrated and described in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that all changes and modifications that come within the spirit of the invention are desired to be protected.