Patent Publication Number: US-2023145934-A1

Title: Piston lock system for agricultural equipment

Description:
BACKGROUND OF THE INVENTION 
     Agricultural equipment, such as combine harvesters that are used to gather agricultural crops, typically have a header that is configured to remove the crop material from the ground, and a feeder housing that conveys the crop material to the main body of the vehicle for processing and temporary storage. The feeder typically is encased in a feeder housing, which may be connected to the vehicle chassis by hydraulic cylinders, in order to allow the header to move relative to the chassis. At times, it may be necessary to extend the hydraulic cylinders to raise the header out of contact with the ground. For example, it may be desirable to raise the header during road transport and other non-harvesting movements, and to allow service of the header and related parts. Under these circumstances (and especially during service), it may be desirable to lock the feeder in the raised position to inhibit accidental lowering of the feeder and header. 
     One way to lock the feeder in the raised position is to place a blocking member around the piston member of a hydraulic actuator that connects the feeder (and thus the header) to the vehicle chassis. For example, a lock in the form of a rigid rod or shaft having an open slot along the side can be slipped over the piston when it is extended from the cylinder, with the ends of the lock terminating adjacent to the two exposed ends of the piston. One end of the lock rests against the end face of the cylinder, and the other end of the lock rests against the end fitting of the cylinder (or another adjacent structure, such as a clevis into which the end fitting is installed), thereby preventing the piston from retracting into the cylinder. 
     It is also known to connect multiple cylinder locks to each other, such that they can be simultaneously moved into place over respective pistons. U.S. Pat. No. 4,529,215, which is incorporated herein by reference, discloses a cylinder lock member in the form of two straps that are pivotally connected to the free end of the piston. Multiple lock members may be connected to each other by a pivot shaft that extends between the cylinder assemblies. In use, the lock members rotate out of the plane defined by the cylinder assemblies. This requires a large clear space adjacent to the cylinder assemblies, and limits or prohibits the applicability of this mechanism when there is no free space to allow the lock members to rotate. Thus, such a mechanism is only feasible when there is sufficient room for the system. 
     While various cylinder lock mechanisms are known, it has been found that they can be cumbersome and time-consuming to operate, and may not have sufficient strength to hold large modern headers and feeders. 
     This description of the background is provided to assist with an understanding of the following explanations of exemplary embodiments, and is not an admission that any or all of this background information is necessarily prior art. 
     SUMMARY OF THE INVENTION 
     In one exemplary aspect, there is provided a piston lock system comprising: a first cylinder extending from a first fixed cylinder end to a first free cylinder end; a second cylinder extending from a second fixed cylinder end to a second free cylinder end, wherein the first cylinder and the second cylinder are spaced in a transverse direction to define a planar region therebetween; a first piston telescopically connected to the first cylinder and extending through the first free cylinder end from a first sliding piston end contained in the first cylinder to a first free piston end located outside the first cylinder; a second piston telescopically connected to the second cylinder and extending through the second free cylinder end from a second sliding piston end contained in the second cylinder to a second free piston end located outside the second cylinder; a first piston lock movably connected to the first cylinder and extending from a first proximal lock end to a first distal lock end, the first piston lock being movable in the transverse direction within the planar region between a first unlocked position in which the first piston lock is not located between the first free cylinder end and the first free piston end, and a first locked position in which the first piston lock is located between the first free cylinder end and the first free piston end; a second piston lock movably connected to the second cylinder and extending from a second proximal lock end to a second distal lock end, the second piston lock being movable in the transverse direction within the planar region between a second unlocked position in which the second piston lock is not located between the second free cylinder end and the second free piston end, and a second locked position in which the second piston lock is located between the second free cylinder end and the second free piston end; and a control link operatively connecting the first piston lock to the second piston lock, and configured to simultaneously move the first piston lock between the first locked position and the first unlocked position, and the second piston lock between the second locked position and the second unlocked position. 
     In another exemplary aspect, there is provided an agricultural combine comprising: a chassis configured for movement on a surface; a feeder housing pivotally connected to the chassis; and a piston lock system such as described in the foregoing aspect and examples. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of inventions will now be described, strictly by way of example, with reference to the accompanying drawings, in which: 
         FIG.  1    schematically illustrates a side view of an example of an agricultural combine having a piston lock system such as described herein. 
         FIGS.  2 A and  2 B  are top plan views of a piston lock system, shown in the unlocked and locked positions, respectively. 
         FIGS.  3 A and  3 B  are isometric views of the piston lock system of  FIGS.  2 A and  2 B , shown in the unlocked and locked positions, respectively. 
         FIG.  4    is a schematic illustration of an exemplary lost motion connection between a piston lock and a cylinder. 
         FIGS.  5 A and  5 B  are top plan views of another piston lock system, shown in the unlocked and retracted position, and the extended and locked position, respectively. 
         FIG.  6    is a top plan view of one actuator side of another piston lock system, with the other actuator and related parts omitted from view. 
         FIG.  7    is a top plan view of another piston lock system, shown in the unlocked position. 
     
    
    
     In the figures, like reference numerals refer to the same or similar elements. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the present invention provide piston lock systems which may be used in agricultural equipment (e.g., combines, windrowers, etc.), or in other environments. However, the invention is not limited to any particular application except as may be specifically recited in the claims. 
     Referring to  FIG.  1   , an example of an agricultural vehicle  100 , which in this case is an agricultural combine, is schematically illustrated. The vehicle  100  includes a chassis  102  that is supported for movement on the ground by wheels  104  (e.g., pneumatic tires or tracked wheels). A header assembly  106  is attached to the combine  100  and configured to receive crop material and convey such material to a threshing and separating system  108  located in or on the chassis  102 . The threshing and separating system  108  separates grain from the remaining crop material (also known as “material other than grain,” “MoG,” or “residue”). The separated grain is stored in a hopper  110 , and the MoG is evacuated to the trailing path of the vehicle  100  by a spreader  112 . 
     The header assembly  106  comprises a feeder housing  114  and a header  116 . The feeder housing  114  is pivotally connected to the chassis  102  at a horizontal pivot  118 . One or more actuators  120  are connected between the chassis  102  and the feeder housing  114 . Each actuator comprises a hydraulic cylinder and piston assembly with a piston lock system, such as described in more detail below. 
     The features described in relation to  FIG.  1    are generally conventional, except for the actuators, and particularly the piston lock system, and no further explanations of their structures or operations are necessary. 
     Referring now to  FIGS.  2 A- 3 B , a first example of a piston lock system is shown and described in detail. The piston lock system is shown installed on a first actuator  120   a  and a second actuator  120   b . Each actuator  120  comprises a cylinder  200  extending from a fixed cylinder end  202  to a free cylinder end  204 , and a piston  206  extending through the free cylinder end  204  from a sliding piston end  208  to a free piston end  210 . The sliding piston end  208  is contained in the cylinder  200 , and the free piston end  210  is located outside the cylinder  200 . The piston  206  is telescopically slidable relative to the cylinder  200  in a manner that is conventional in the art of hydraulic actuators. For example, a hydraulic system may include a one or more hydraulic ports  212  that are fluidly connected to the interior of the cylinder, and configured to convey pressurized hydraulic fluid to extend or retract the piston  206  relative to the cylinder  200 . Such hydraulic systems are conventional, and need not be described in further detail herein. 
     When installed on a vehicle  100 , the cylinders  200  are configured to be coplanar or parallel throughout their respective ranges of motion. When coplanar, the fixed cylinder ends  202  and free piston ends  210  all lie in a common plane. When parallel, the fixed cylinder ends  202  and free piston ends  210  all lie in a common plane, and the cylinders  200  and pistons  206  are parallel within the common plane. In either case, some variation may occur during regular use due to differential loading and slight differences in hydraulic system operations. Regardless of whether they are coplanar or parallel, the cylinders  200  are spaced from each other in a transverse direction T to define a planar region  214  between them. 
     Each actuator  120   a ,  120   b  has a respective piston lock  216  that is movably connected to the cylinder  200 , to move between an unlocked position ( FIGS.  2 A and  3 A ) and a locked position ( FIGS.  2 B and  3 B ). In their unlocked positions, the piston locks  216  are not located between the free cylinder end  204  and the free piston end  210 , and thus do not inhibit retraction of the piston  206  into the cylinder  200 . In their locked positions, however, the piston locks  216  are located between the free cylinder end  204  and the free piston end  210 , and prevent retraction of the piston  206  into the cylinder  200 . 
     As used herein, the “unlocked position” and the “locked position” are understood to be the final extents of travel of the piston locks  216 . It will be appreciated that the piston locks  216  may still effectively lock the pistons  206  in some range of travel just before reaching the “locked position,” and may not lock the pistons  206  in some range of travel before reaching the “unlocked position.” 
     Each piston lock  216  extends from a proximal lock end  218  to a distal lock end  220 , and is configured to withstand loads that might otherwise move the pistons  206  back into the cylinders  200 . For example, each piston lock  216  may be formed as a simple round or square bar, or as a bar having a more complex profile shape, such as an L-shape or an I-shape. In the shown example, the piston locks  216  are formed with a C-shaped profile, having a slot  300  ( FIG.  3 B ) that extends from the proximal lock end  218  to the distal lock end  220 . The slot  300  is dimensioned to surround opposite sides of the piston  206  when the piston lock  216  is in the locked position. 
     The piston locks  216  of both actuators  120   a ,  120   b  are connected to the respective cylinders  200  such that they move in the transverse direction T within the planar region  214  as they travel between the unlocked and locked positions. Thus, the piston locks  216  remain generally in the plane defined by the actuators  120   a ,  120   b , and out of contact with adjacent structures. This provides a compact arrangement and takes advantage of what is normally an empty space between actuators  120  in vehicles  100  such as agricultural combines. 
     A control link operatively connects the piston locks  216  to each other. The control link is configured to simultaneously move the piston locks  216  between their locked and unlocked positions. Thus, the piston locks  216  operate in unison. The control link may have any suitable configuration. In the shown example, each piston lock  206  is pivotally connected to its respective cylinder  200  at a respective pivot  222 , and the control link comprises a rod  224  connecting the piston locks  206  to each other. More specifically, a first end  226  of the rod  224  is pivotally connected to one piston lock  216  at a position that is offset from that piston lock&#39;s pivot  222  by a first distance D 1 , and a second end  228  of the rod  224  is pivotally connected to the other piston lock  216  at a position that is offset from that piston lock&#39;s pivot  222  by a second distance D 2 . 
     This control link arrangement provides a four-bar linkage with a virtual fixed bar being formed between the two piston lock pivots  222 , and the relative rotation rates of the two piston locks  216  being defined by the relative values of the first distance D 1  and the second distances D 2 . As explained in more detail below, this allows the piston locks  216  to be rotated simultaneously in the same plane within interfering with each other. Other embodiments may use other mechanisms to transfer movement of one piston lock  216  to the other piston lock  216 . For example, the piston locks  216  may be connected by belts, pulleys, chains, sprockets, gears, and other power transmission devices. Other alternatives and variations will be apparent to persons of ordinary skill in the art in view of the present disclosure. 
     One or both of the piston locks  216  may include a handle  230  that is configured for operation by a user to move the piston locks  216  between the locked and unlocked positions. The handle  230  preferably is shaped and located to allow convenient operation by the user. For example, the handle  230  may have a loop shape, such as shown, to allow grasping at multiple positions. The handle  230  also may serve an auxiliary purpose of providing a clear visual indicator when the piston locks  216  are in the locked position. For example, the handle or handles  230  may be positioned outside the planar region  214  between the actuators  120   a ,  120   b  when the piston locks  216  are in the locked position, and inside the planar region  214  when the piston locks  216  are in the unlocked position. The handle  230  also may have a distinct color or shape to help indicate the locked or unlocked position of the piston locks  216 . 
     Each piston lock  216  has a range of motion between its respective unlocked and locked positions. In the shown example, the piston locks  216  each rotate about a single pivot  222 , and each range of motion comprises a respective angle of rotation A 1 , A 2 . In this case, one angle of rotation A 1  is greater than the other angle of rotation A 2 . Thus, the piston lock  216  having the greater angle of rotation A 1  retracts farther from the locked position to reach its unlocked position, as compared to the piston lock  216  having the smaller angle of rotation A 2 . As a result, when the piston locks  216  are in their unlocked positions, the piston locks  216  overlap each other in a longitudinal direction L along the planar region that is perpendicular to the transverse direction. This is beneficial in this embodiment to ensure that the piston locks  216  do not interfere (i.e., contact each other), as they travel between their respective locked and unlocked positions. To this end, the angles of rotation A 1 , A 2 , as well as the instantaneous positions of the piston locks  216  throughout their entire respective angles of rotation A 1 , A 2 , are preferably selected to prevent contact at any time during motion between the locked and unlocked positions. The different angles of rotation A 1 , A 2  can be established, for example, by adjusting the relative magnitudes the offset distances D 1 , D 2 , and modifying other properties of the four-bar linkage formed by the control link members, as known in the art of linkage design in view of this disclosure. 
     In other embodiments, the angles of rotation may be identical. In such cases, interference between the piston locks  216  may be avoided by offsetting them in a direction orthogonal to the planar region  214 . Such offset can be accomplished by tilting their respective pivots  222  in opposite direction to cause them to move in the orthogonal direction as they move to the unlocked position, while still remaining generally between the cylinders  200 , or by shaping the piston locks  216  such that they do not interfere (e.g. forming interleaving slots or forming one to pass above or below the other. In still other cases, the cylinders  200  may be spaced far enough in the transverse direction T that contact between the piston locks  216  is not possible in any event. Other alternatives and variations will be apparent to persons of ordinary skill in the art in view of the present disclosure. 
     The piston locks  216  may include features to help ensure proper motion to the locked position. For example, the each piston lock  216  may have an angled face  232  ( FIG.  2 B ) at the distal lock end  220 , which is configured as a ramp to drive the free piston end  210  towards the extended position piston as the piston lock  216  is rotated to the locked position. 
     When the piston locks  216  are in the locked position, they prevent the piston  206  from retracting into the cylinder  200  by forming a physical obstruction between the free piston end  210  and the free cylinder end  204 . To this end, the free piston end  210  may have a T-shape with a flat surface  302  facing towards the free cylinder end  204 , such as shown in  FIG.  3 A . The flat surface  302  abuts the distal lock end  220 , and the proximal lock end  218  abuts the free cylinder end  204 , thus forming a direct support path, and minimizing the number of parts that must bear the weight applied to the free piston end  210 . It will be appreciated that the T-shaped free piston end  210  may be modified or replaced with other shapes that are suitable to provide the necessary support. 
     It will also be understood that the piston locks  216  may not be as long as the full stroke of the piston  206  relative to the cylinder  200 . Thus, when the piston locks  216  are in the locked position, there may be a gap between the free cylinder end  204  and the proximal lock end  218 , or between the distal lock end  220  and the free piston end  210 . Such a gap can be seen in the example shown in  FIG.  2 B . When a gap is present, the assembly can be placed into the final service position by retracting the piston  206  into the cylinder  200  until contact is made between the free cylinder end  204  and the proximal lock end  218 , and the distal lock end  220  and the free piston end  210 . Such contact may generate a load that holds the piston lock  216  in the locked position, or the shapes of the parts may be selected such that the piston lock  216  cannot be rotated out of the locked position once the piston is retracted, but neither of these features is strictly required. 
     In some cases, it may be desirable to ensure that there is full contact between the free piston end  210  and the distal lock end  220 , and between the free cylinder end  204  and the proximal lock end  218 . Contact between the free piston end  210  and the distal lock end  220  is readily accomplished by retracting the piston  206  until contact is made. However, contact between the proximal lock end  218  and the free cylinder end  204  may be inhibited by various factors, such as misplacement of the pivot  222 , thermal expansion of the parts, wear on the parts, and so on. For example, if the pivot  222  is too close to the free cylinder end  204 , the proximal lock end  218  may be unable to contact the free cylinder end  204 , resulting in loads being transferred from the free piston end  210  to the pivot  222 . 
     To account for such variables, the pivot  222  may include a lost motion connection (i.e., a connection that provides limited free movement between the parts, such as a pin in a slot) that allows the proximal lock end  218  to move into contact with the free cylinder end  204  under any expected operating conditions. An example of a lost motion connection is shown in  FIG.  4   . Here, the pivot  222  is formed by a pin  400  that fits in a hole  402 . The hole  402  is oversized—i.e., larger than the pin  400 —and thus allows the piston lock  216  to move relative to the cylinder  200 , as shown by the double-headed arrow. In this example, the pin  400  is fixed to the cylinder  200 , and the oversized hole  402  or slot is formed in an arm  404  connected to the piston lock  216 . Other embodiments may have other arrangements. For example, an oversized hole  402  or slot may be formed in a boss extending from the piston  200 , and the pin  400  may be provided as a bolt that extends through the arm  404 . The size of the pin  400  and hole  402  may be selected as necessary to account for manufacturing tolerances, expected wear on the parts, changes in operating conditions, and so on. The illustrated hole  402  is round, but oval, rectangular and other shapes may be used to allow relative movement at the pivot  222 . Other alternatives for lost motion connections will be apparent to persons of ordinary skill in the art in view of the present disclosure. 
       FIGS.  5 A and  5 B  show another embodiment, in which the piston lock system includes retainers  500  to hold the piston locks  216  in one or more positions. In this case, a first retainer  500   a  is provided on the cylinder  200  of one actuator  120   a , and a second retainer  500   b  is provided on the cylinder  200  of the other actuator  120   b . As shown in the inset image, each retainer  500  comprises a resilient snap clip having two arms  502  that can flex away from each other to receive and hold an appropriately sized snap pin  504 . A first pin  504   a  is provided on one piston lock  216  to engage the first retainer  500   a  when the piston locks  216  are in the locked position, as shown in  FIG.  5 B . Similarly, a second pin  504   b  is provided on the other piston lock  216  to engage the second retainer  500   b  when the piston locks  216  are in the unlocked position, as shown in  FIG.  5 A . 
       FIGS.  5 A and  5 B  also illustrate the pistons  206  being in the telescopically retracted position ( FIG.  5 A ) and the telescopically extended position ( FIG.  5 B ). 
       FIG.  6    illustrates another example of retainers  500  to hold the piston locks  216  in the locked and unlocked positions. In this case, both retainers  500   a  and  500   b  are provided on one piston lock  216 , and configured to engage respective pins  504   a  and  504   b  on a single cylinder  200 . 
     Other embodiments may use other arrangements of retainers to hold the piston locks  216  in one or more positions. For example, the positions of the retainers  500  and pins  504  may be reversed or moved to any suitable location. It will also be appreciated that the retainers  500  may comprise devices other than the shown resilient snap clips and snap pins. For example, the retainers  500  may comprise magnets, manually-operated hooks or pins, and so on. Other alternatives and variations will be apparent to persons of ordinary skill in the art in view of the present disclosure. 
       FIG.  7    illustrates another example of a piston lock system. In this case, the piston lock system is essentially the same as the embodiment of  FIGS.  2 A- 3 B , but instead of having a manually-operated handle, it has a powered actuator  700  configured to move the piston locks  216  between the locked position and the unlocked position. The actuator  700  may comprise a pneumatic, hydraulic or electric actuators (e.g. a telescoping piston and cylinder assembly), or the like. The actuator  700  is shown acting on one of the piston locks  216 , but it may instead act on the rod  224  or on another link that is connected to the remaining parts. 
     It will be appreciated that embodiments such as describe herein can be used in various locations on agricultural vehicles and equipment, particularly those having multiple actuators. For example, the actuators  120   a ,  120   b  may be mounted with the fixed cylinder ends  202  connected to a vehicle chassis  102 , and the free rod ends  210  connected to a feeder housing  114 , or vice-versa. Such connections can be made in the manner of a conventional actuator, and thus embodiments may be provided as a retrofit assembly for an existing vehicle  100 . 
     It is expected that embodiments will provide easier and more efficient options to lock pistons of actuators in the extended positions, and thus can improve serviceability and safety of such devices. Furthermore, embodiments the ability to simultaneously operate lock pins on multiple actuators can have a significant benefit in cases in which locking a single actuator is not sufficient to adequately secure a load. For example, modern agricultural combine headers having two actuators can weigh too much to be reliably held by a single one of its actuators, in which case the ability to simultaneously lock both actuators is particularly desirable. 
     The present disclosure describes a number of inventive features and/or combinations of features that may be used alone or in combination with each other or in combination with other technologies. The embodiments described herein are all exemplary, and are not intended to limit the scope of the claims. It will be appreciated that various aspects of the embodiments described herein may be provided as component parts or as subassemblies. It will also be appreciated that the inventions described herein can be modified and adapted in various ways, and all such modifications and adaptations are intended to be included in the scope of this disclosure and the appended claims.