Abstract:
A telescoping crane boom having a rotary locking mechanism. A motor drives a rotating element about an axis parallel to the axis of the crane boom. The rotation of the rotating member causes a pin to selectively lock and unlock sections of the telescoping crane boom.

Description:
RELATED APPLICATIONS 
       [0001]    The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. Patent Application Ser. No. 62/326,960, filed Apr. 25, 2016, which is hereby incorporated by reference. 
     
    
     BACKGROUND 
     1. Technical Field Text 
       [0002]    Embodiments are directed to the general field of mobile cranes and more particularly to telescoping members such as booms. 
       2. Background Information 
       [0003]      FIG. 1  illustrates a crane  10 . Because the crane  10  is mobile and may be moved while on site, and is also transported from site to site, the crane  10  is sized to travel over the road and for transport on commonly available transport systems. Due to size constraints, the crane  10  includes extendable components to allow the crane  10  to increase in dimension while at the job site. For example, in  FIG. 1 , the crane  10  has a telescoping boom  12 . The minimum length of the boom  12  must be short enough for safe highway travel, as well as travel around a job site. However, a lift job typically requires a much longer boom  12 . To allow for a longer boom  12 , the crane  10  has multiple boom segments that the nest within one another. 
         [0004]    While the general concept of a telescoping boom  12  is fairly straightforward, its actual implementation is complex. In order to achieve a maximum length, a telescoping boom  12  typically has multiple sections, with each section nesting in an adjacent section.  FIG. 2  illustrates an enlarged view of the tip of the boom  12  of the crane  10  of  FIG. 1 . This boom  12  has a base section  16 , three intermediate sections  18 ,  20 ,  22 , and an inner section  24 . These sections each extend and retract depending on the necessary length of the boom  12 . Furthermore, a single drive system, such as an inverted hydraulic actuator, is used to move the sections  18 ,  20 ,  22 ,  24  in and out of the base section  16 . The use of a single drive avoids the excess weight that would result from the use of multiple drive systems. Once a section is extended from the base section  16 , it is locked to the section it is nested within. 
         [0005]      FIG. 3  illustrates a schematic of a drive system for extending a boom in the form of an inverted hydraulic actuator  26 . The inverted hydraulic actuator  26  is located within the base section  16  with a rod  28  connected to the base section  16  and a cylinder  30  that is free to move relative to the base section  16  when the inverted hydraulic actuator  26  is actuated. A pinning head  32  is disposed at a rod end of the cylinder  30  and has a cylinder-to-boom section pin  34  for pinning the pinning head  32  to a boom section and a boom section connection pin actuator  36  for actuating a pin to lock adjacent boom sections together once extended. 
         [0006]    In operation, the pinning head  32  actuates the boom section pin  34  to pin the inner boom section  24  to the cylinder  30 . The cylinder  30  is actuated, moving the inner section  24  out of the base section  16 . Once the inner section  24  is extended to a desired distance, the inner section  24  is pinned to the next boom section  22  with the boom section connection pin actuator  36 . The cylinder to boom section pin  34  is then released from the inner boom section  24  and the cylinder  30  is retracted. Once retracted, the pinning head  32  is pinned to the next section  22  with the cylinder-to-boom section actuator  34 . The next section  22  extends from the base section  16 , pushing the inner section  24 , which is now pinned to the next section  22 , out farther as well. Once extended, section  22  is pinned to section  20  with the boom section connection pin actuator  36  to lock the sections together. The cylinder-to-boom section pin actuator  34  is released and the cylinder  30  is retracted. This process continues, extending boom sections until the desired boom length is achieved. 
         [0007]    The pinning head  32  is responsible for at least two pinning operations. The first is actuating the boom section connection pin  36  to couple the boom sections together. This is done with a small hydraulic actuator  37  mounted parallel to the inverted hydraulic actuator  26  as shown in  FIG. 3 . The second pinning operation actuates a pin laterally, perpendicular to the direction of travel of the boom sections; this pinning operation is performed with hydraulic pressure exposed to surfaces of the pin internal to the pinning head  32 . However, this pin translation is perpendicular to the main actuator. 
         [0008]    To simplify the design, each of the hydraulic actuators operates using the same hydraulic source as the main inverted hydraulic actuator  26 . The pressurized hydraulic fluid is controlled by a control valve  38  which selectively pressurizes the boom section connection pin actuator  36  or the cylinder to boom section pin actuator  34 . Because the control valve  38  and the and pin actuators  34 ,  36  move with the telescoping cylinder  30 , the hydraulic line  40  needs to adjust to compensate for the varying distance between the hydraulic pressure source and the actuators  34 ,  36 . This may be accomplished through a trombone tube which extends in length when the telescoping cylinder  30  is extended. However, because the tube&#39;s internal volume changes as the cylinder  30  is retracted and extended, the speed at which the cylinder  30  is retracted and extended is limited to avoid excessive pressure changes in the trombone tube. 
         [0009]    Current pinning systems such as that shown in  FIG. 3  suffer from further shortcomings such as being a dead end system. It is very difficult to bleed air from the system since there is no return flow from the pinning actuators  34 ,  36 . The control system is also very complicated for a hydraulic system, requiring the cylinder  30  to be actuated across large distances (such as 10 meters) while extending boom sections, and then precisely positioned to within 5 mm of a pinning hole for pinning the cylinder  30  to a section. To improve validation of cylinder  30  positioning, current systems may use proximity switches within the pinning head  32  (which are in a virtually unmaintainable location), and proximity switches with the pinning head components near the boom section weldment. This requires a large amount of control system complexity and precision assembly procedures. 
         [0010]    Finally, in addition to complexity to position cylinder  30  to a boom section, there is no use of a positive identification of the boom section being approached or connected to. Thus, the system must keep track of where the cylinder  30  is and which boom sections it has connected in the past. Furthermore, this logic must be kept in non-volatile memory so that after a power cycle, the control system still knows where the sections were from the previous use. 
         [0011]    What is needed is a telescoping boom that addresses the shortcomings in current boom design. It would be beneficial if the system was simpler than existing systems while allowing the boom to extend and retract rapidly independent of the lock actuators. 
       BRIEF DESCRIPTION 
       [0012]    In one aspect of the description, a telescoping boom is disclosed. The telescoping boom includes a base section, a first telescoping boom section, a linear actuator, a rotary element, and a rotary actuator. The base section has a base end and a telescoping end. The first telescoping boom section is disposed within the main boom section and has a pin receiver configured to receive a pin. The linear actuator is disposed within the main boom section and has a stationary portion and an actuated portion. The actuated portion is configured to extend and retract longitudinally relative to the base section. The rotary element is coupled to the actuated portion and has an axis of rotation parallel to a longitudinal axis of the main boom section and a pin perpendicular to the axis of rotation. In a first configuration the pin engages the first telescoping boom section and in a second configuration radially offset from the first configuration the pin does not engage the first telescoping section. The rotary actuator is coupled to the main boom section and the rotary element and is configured to rotate the rotary element relative to the main boom section. 
         [0013]    In some embodiments, the pin receiver has a ramped engagement in a longitudinal direction. In some embodiments, the first configuration extends the pin laterally and the second configuration retracts the pin laterally. In some embodiments, the first configuration is offset angularly from the second configuration. 
         [0014]    In some embodiments, the boom further includes a plurality of proximity sensors disposed in the main boom section and the plurality of proximity sensors are configured to identify a boom section. 
         [0015]    In some embodiments, the telescoping boom includes a second telescoping boom section disposed within the first telescoping boom section and the second telescoping boom section has a second receiver configured to receive the pin. 
         [0016]    In another aspect a crane is disclosed. The crane includes a chassis and an upper works coupled to the chassis. The upper works includes the telescoping boom described previously. 
         [0017]    In some embodiments, the pin receiver has a ramped engagement in a longitudinal direction. In some embodiments, the first configuration extends the pin laterally and the second configuration retracts the pin laterally. In some embodiments, the first configuration is offset angularly from the second configuration. 
         [0018]    In some embodiments, the boom of the crane further includes a plurality of proximity sensors disposed in the main boom section and the plurality of proximity sensors configured to identify a boom section. In some embodiments, the boom further includes a second telescoping boom section disposed within the first telescoping boom section, the second telescoping boom section having a second receiver configured to receive the pin. 
         [0019]    In another aspect, a rotary locking mechanism for a crane boom is disclosed. The rotary locking mechanism includes a rotating element, a motor, and at least one pin. The motor has a bearing surface configured to interact with an inverted hydraulic cylinder. The motor is configured to drive the rotating element about an axis of rotation. The at least one pin has a first configuration corresponding to the rotating element being in a first angular orientation and a second configuration corresponding to the rotating element being in a second angular orientation. 
         [0020]    In some embodiments, a body of the motor is fixed relative to the bearing surface of the rotating element. In some embodiments, a body of the motor is fixed relative to the at least one pin. In some embodiments, the at least one pin is configured to rotate from the first configuration to the second configuration. In some embodiments, the at least one pin is configured to move laterally from the first configuration to the second configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  illustrates an overview of an existing mobile crane. 
           [0022]      FIG. 2  illustrates a detailed view of the tip of a boom of a mobile crane showing the nested boom sections. 
           [0023]      FIG. 3  illustrates a schematic of an actuator. 
           [0024]      FIG. 4  illustrates an embodiment of a rotary locking mechanism. 
           [0025]      FIG. 5  illustrates the embodiment of  FIG. 4  with the pin in a locked position. 
           [0026]      FIG. 6  illustrates an embodiment of a rotary locking mechanism. 
           [0027]      FIG. 7  illustrates the embodiment of  FIG. 6  with a retracted pin. 
           [0028]      FIG. 8  illustrates a system of proximity switches for determining a boom segment. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The present embodiments will now be further described. In the following passages, different aspects of the embodiments are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. 
         [0030]      FIG. 4  illustrates an embodiment of a rotating locking mechanism  42  for coupling an inverted hydraulic actuator  26  to a telescoping boom section. For simplicity, the rotating locking mechanism  42  is shown without the base boom section  16 , the telescoping boom sections  18 ,  20 ,  22 ,  24 , and the rod  28  of the inverted hydraulic actuator  26 . In operation, the rotating locking mechanism  42  would be disposed internal to the base main boom section  16  with the rod  28  of the inverted hydraulic actuator  26  extending through the rotating locking mechanism  42 . 
         [0031]    The rotating locking mechanism  42  includes a motor  44  for providing a rotary motion and a rotating element  46 . The motor  44  may be an electrical motor, a pneumatic motor, or a hydraulic motor. In conventional booms, electrical power may already be provided by way of a cable reel mechanism that is a part of the conventional pinned boom design (for electrical power for solenoids in valves and electrical communications). Similarly, pneumatic power might also be provided by a reel. Pneumatic power is advantageous in that it is able to store energy over a period of time (building pressure), and then being released in a sudden demand for power. 
         [0032]    In  FIG. 4 , the conventional pinning head  32 , has been removed and replaced with the rotating locking mechanism  42 . The motor  44  is rigidly mounted to the inverted hydraulic actuator  26  to prevent its body  54  from rotating relative to the inverted hydraulic actuator  26 . The driveshaft of the motor drives the rotating element  46  through a circular rack  48  and pinion  50  gear combination. Other techniques for transmitting torque between the motor  44  and the rotating element  46  are contemplated such as a chain drive, pulley system, or compound gears. In some embodiments, it is possible to reverse the elements, such that the motor  44  is mounted to the rotating element  46  and rotates with the element while the circular rack  48  remains stationary. 
         [0033]    The rotating element  46  has a cylinder-to-section pin  52  that extends from an outer surface  56  of the rotating element  46 . The rotating element  46  may have protrusions  58  on the outer surface  56  of the rotating element that interact with proximity switches  60  on a non-rotating portion of the rotating locking mechanism  42  to detect the relative position of the rotating element  46 . The proximity switches  60  may be used to determine the two extents of the rotating element  46 . The rotating element  46  may have a roller bearing for the interface between the rotating element  46  and the inverted hydraulic actuator  26 . Other embodiments may use a journal bearing or a thrust bearing between the rotating element  46  and the inverted hydraulic actuator  26 . 
         [0034]    The cylinder-to-boom section pin  52  transmits an axial force from the inverted hydraulic actuator  26  to a telescoping boom section through the rotating mechanism  46  to extend the boom  12 . In some embodiments, there is no de-rating for the inverted hydraulic actuator  26  as the boom  12  is extended or retracted, such that the interface between the telescoping boom section and the inverted hydraulic actuator  26  transmits the full load of the boom  12  during telescoping operations. 
         [0035]      FIG. 5  illustrates the rotating locking mechanism  42  of  FIG. 4  along with a partial view of a telescoping boom section. In this view, the rotating locking mechanism  42  is shown engaged in a locked position with the cylinder-to-section pin  52  engaged with a the telescoping boom section. The telescoping boom section has a recess  62  that receives the cylinder-to-boom section pin  52 . The recess  62  has a ramped engagement region  64  that guides the cylinder-to-boom section pin  52  into position. The rotating locking mechanism  42  is able to pin the inverted hydraulic actuator  26  to the telescoping boom section if the cylinder-to-boom section pin  52  encounters the recess  62  at either the ramped engagement region  64 , or the recess  62  itself. In some embodiments, if the cylinder-to-boom section pin  52  encounters the ramped engagement region  64 , the cylinder-to-boom section pin may push either the inverted hydraulic actuator  26  or the telescoping boom section axially to align the cylinder-to-boom pin and the recess. 
         [0036]    In operation, once the rotating locking mechanism is in the general location of engagement, the motor  44  may attempt to rotate the rotating element  46  and consequently the cylinder-to-boom section pin  52  into the engagement with the recess  62 . If the cylinder-to-boom section pin  52  and the recess  62  are not aligned, the inverted hydraulic actuator  26  may be extended or retracted to assist engagement. In embodiments using a pneumatic drive, the motor  22  may be powered even if the cylinder-to-boom section pin  52  is not in position to engage the recess  62 . Then, once the cylinder-to-boom section pin  52  encounters the recess  62  as the inverted hydraulic actuator  26  is moved axially, the air motor would move the cylinder-to-boom section pin  52  pin into the recess  62 . 
         [0037]    In some embodiments, the motor  44  may have a rotational encoder to indicate which telescoping boom section the cylinder-to-boom section pin  52  is engaging with. For example, each telescoping boom section may have a different angular orientation of the recess  62  such that a bottom of each recess  62  has different angular orientation. By measuring the angular orientation at which the cylinder-to-boom section pin  52  encounters the bottom of the recess  62 , it is possible to identify the telescoping boom section being actuated. 
         [0038]    In some embodiments, rather than position the rotating locking mechanism  42  at the recess  62  and then rotating the cylinder-to-boom section pin  52  into engagement with the recess  62 , the rotating locking mechanism  42  may be positioned to a known position offset from the recess  62 . The motor  44  may then be powered at the same time as the inverted hydraulic actuator  26 . As the recess  62  comes into position, the rotatory locking mechanism moves the cylinder-to-boom section pin  52  into the locked position. 
         [0039]      FIG. 6  illustrates another embodiment of a rotary locking mechanism  70 . In this embodiment, a rotating element  72  has at least one slot  74  having a first end  76  towards the axis of rotation of the rotating element  72  and a second end  78  positioned away from the axis of rotation. A cylinder-to-boom section pin  80  is disposed on a side of the rotary locking mechanism  70  and is able to move laterally to engage and disengage telescoping boom sections. The rotary locking mechanism  70  has a recess  82  parallel to the axis of the inverted hydraulic actuator  26  that aligns with the cylinder-to-boom section pin  80  and the slot  74  in the rotating element  72 . A pin actuator  84  resides in the recess  82  and connects the cylinder-to-boom section pin  80  to the slot  74  of the rotating element  72 . When the motor  86  is powered, it causes the rotating element  72  to turn and the slot  74  forces the pin actuator  84  to move laterally, as shown in  FIG. 7 . The lateral movement of the pin actuator  84  causes the cylinder-to-boom section pin  80  to move laterally, locking boom sections to the inverted hydraulic actuator  26 . 
         [0040]    In some embodiments, it may be beneficial to improve the system for aligning the inverted hydraulic actuator  26  with the telescoping boom sections. It would be beneficial for the new system to indicate general alignment and identify which boom section has been approached. This information is valuable for the control system and removes some of the need to store a history of which operations have been performed to determine the current state of the boom. 
         [0041]      FIG. 8  illustrates an embodiment of a rotary locking mechanism  42  having a positive boom section identification system. The rotating locking mechanism  42  includes an array of proximity switches  88  and the boom sections include section identifying targets  90 . The section identification targets  90  are offset laterally and allow unique identification of the boom sections. A pattern of three proximity switches  88  and corresponding targets  90  can uniquely identify up to seven boom sections (patterns such as 0-0-1, 0-1-0, 0-1-1, 1-0-0, 1-0-1, 1-1-0, and 1-1-1). The identification targets  90  can also perform a dual function in indicating both the boom section, and the engagement area for the rotary locking mechanism  42  to actuate the cylinder-to-boom section pin. 
         [0042]    It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.