Abstract:
An axle lift assembly includes a vehicle configured to support a load. A slide assembly has a member that is movable along a longitudinal extent of the vehicle. The slide assembly is operable to secure the member relative to the vehicle at a select position along the longitudinal extent of the vehicle. A swing arm has a first end pivotally coupled with the member and an opposing second end biased away from the vehicle. The swing arm is configured to support a wheel assembly with a tire for contacting a ground surface. An actuator is operably interconnecting the member and the swing arm for raising the wheel assembly toward the vehicle to lift the tire away from the ground surface. The slide assembly and the actuator are operable to respectively adjust longitudinal and vertical positions of the wheel assembly relative to the vehicle for accommodating a condition of the load.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/189,469 filed on Feb. 25, 2014, entitled “AXLE LIFT ASSEMBLY,” which is a continuation of U.S. patent application Ser. No. 13/966,789 filed on Aug. 14, 2013, now issued as U.S. Pat. No. 8,695,998, entitled “AXLE LIFT ASSEMBLY.” U.S. patent application Ser. No. 13/966,789 claims priority under 35 U.S.C. §119(e) to, and the benefit of, U.S. Provisional Patent Application No. 61/767,029, entitled “AXLE LIFT ASSEMBLY,” filed on Feb. 20, 2013, the entire disclosure of which is hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to an axle lift assembly, and more particularly, to an axle lift assembly for a vehicle that, in one embodiment, is longitudinally slidable relative to a chassis of the vehicle and actuatable based on weight of a load carried by the vehicle. 
       BACKGROUND OF THE INVENTION 
       [0003]    As businesses attempt to optimize inventory levels to meet variable demand, it is common for modern industrial vehicles, including trucks and trailers, to be used for shipping a wide variety of load types and configurations. In general, it is advantageous to alter a vehicle&#39;s carrying capacity by adding or removing trailers from the vehicle or using alternatively sized trailers to accommodate the mass and volume of the load. For example, for loads with a smaller volume requirement, but a larger mass requirement, it can be beneficial to utilize a vehicle with additional axles for dispersing the weight of the load over more tires. However, it can be inefficient to pull such a trailer when the additional tires are unnecessary to disperse a light load, given that added tires increase friction and weight, as well as increase the cost of roadway tolls. It can also be expensive to own and maintain several vehicles and trailers for various load types and configurations. Nevertheless, to be competitive and profitable it is becoming increasingly more important to reduce a vehicle&#39;s fuel consumption, unnecessary wear on tires, and improve other vehicle inefficiencies. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    According to one aspect of the present invention, an axle lift assembly includes a vehicle configured to support a load. A slide assembly has a member that is movable along a longitudinal extent of the vehicle. The slide assembly is operable to secure the member relative to the vehicle at a select position along the longitudinal extent of the vehicle. A swing arm has a first end pivotally coupled with the member and an opposing second end biased away from the vehicle. The swing arm is configured to support a wheel assembly with a tire for contacting a ground surface. An actuator is operably interconnecting the member and the swing arm for raising the wheel assembly toward the vehicle to lift the tire away from the ground surface. The slide assembly and the actuator are operable to respectively adjust longitudinal and vertical positions of the wheel assembly relative to the vehicle for accommodating a condition of the load. 
         [0005]    According to another aspect of the present invention, an axle lift assembly for a trailer that is configured to support a load includes a member configured to slidably couple with the trailer for adjusting a longitudinal position of the member relative to the trailer. A swing arm has a pivot end coupled with the member. An axle assembly is coupled with the swing arm and is configured to support a tire. An air spring is disposed between the swing arm and the member for biasing the axle assembly away from the member. A pneumatic actuator is operable interconnecting the member and the swing arm. The pneumatic actuator is adjustable between a deflated position configured for the tire to contact a ground surface and an inflated position configured to lift the tire away from the ground surface. 
         [0006]    According to yet another aspect of the present invention, an axle lift assembly for a vehicle includes a member slidably adjustable along a longitudinal extent of the vehicle. A swing arm is pivotably coupled with the member and biased away from the vehicle for supporting a tire. An actuator operably interconnects the member and the arm and is adjustable to raise the swing arm toward the vehicle for lifting the tire away from a ground surface. 
         [0007]    These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    In the drawings: 
           [0009]      FIG. 1  is a top perspective view of a tandem axle assembly with air suspension and having an axle lift assembly, according to one embodiment of the present invention; 
           [0010]      FIG. 1A  is a cross section view of a lug extending from a longitudinal beam of the tandem axle assembly to engage an aperture on a vehicle frame member, taken at line IA-IA of  FIG. 1 ; 
           [0011]      FIG. 2  is a front elevational view of the tandem axle assembly; 
           [0012]      FIG. 3  is a top plan view of the tandem axle assembly; 
           [0013]      FIG. 4  is a bottom plan view of the tandem axle assembly; 
           [0014]      FIG. 5  is a side elevational view of the tandem axle assembly; 
           [0015]      FIG. 6  is a top perspective view of an axle, the associated trailing arms, and the brake assemblies of the axle lift assembly; 
           [0016]      FIG. 7  is a fragmentary bottom perspective view of the axle lift assembly, showing a trailing arm, an air spring, and a pneumatic actuator of the axle lift assembly; 
           [0017]      FIG. 8  is a fragmentary top perspective view of the axle lift assembly, showing a support bracket of the axle lift assembly; 
           [0018]      FIG. 9  is an exploded top perspective view of the support bracket and a pneumatic actuator of the of the axle lift assembly; 
           [0019]      FIG. 10  is a side elevational view of the tandem axle assembly, showing the axle of the axle lift assembly in a ground engagement according to one embodiment; 
           [0020]      FIG. 11  is a side elevational view of the tandem axle assembly, showing the axle of the axle lift assembly in a lifted position; 
           [0021]      FIG. 12  is a flow chart of one embodiment of a system for controlling the axle lift assembly; and 
           [0022]      FIG. 13  is a flow chart of an additional embodiment of a system for controlling the axle lift assembly with a step of monitoring a tire pressure. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0023]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0024]    Referring to  FIG. 1 , the reference number  10  generally designates an axle lift assembly of the present invention. In the illustrated embodiment, the axle lift assembly  10  is shown on a tandem axle assembly  12  that is adapted for use on a vehicle, specifically a rear portion of a semi-trailer. However, it is contemplated that the tandem axle assembly  12  may be used on other vehicles, such as trucks and trailers with various axle arrangements, including semi-trucks, tractors, enclosed trailers, flat bed trailers, trailers with steerable axles, and other wheeled vehicles with more than two axles as generally understood by one having ordinary skill in the art. 
         [0025]    The illustrated tandem axle assembly  12 , as shown in  FIG. 1 , includes a rear axle assembly  14  and a front axle assembly  16 , which may conceivably be reversed in other embodiments. The front and rear axle assemblies  16 ,  14  each include a non-steerable axle  18  laterally extending between a pair of trailing-arm air suspension systems. Conceivably, the rear axle assembly  14  may employ an alternative suspension system. As illustrated, the front and rear axle assemblies  16 ,  14  are extending between a pair of longitudinal beams  20  that extend along a longitudinal extent of the trailer. The longitudinal beams  20  are each slidably coupled with a corresponding frame member  22  that similarly extends along the longitudinal extent of a lower portion of a chassis of the trailer. The longitudinal beams  20  include a locking assembly  24  to prevent sliding movement of the tandem axle assembly  12  relative to the chassis of the trailer. The locking assembly  24  includes a pair of retractable lugs  26  that extend outward from the longitudinal beams  20  to selectively engage a pair of a plurality of apertures  28  that are spaced along a length of the frame member  22 . Engagement of the lugs  26  of the locking assembly with the plurality of apertures  28  restricts sliding movement of the beam  20  relative to the frame member  22 . It is conceivable that in alternative embodiments the lugs and apertures may be reversed or other means to restrict the longitudinal movement of the tandem axle assembly  12  may be employed. 
         [0026]    As further illustrated in  FIG. 1A , a retractable lug  26  is shown extending laterally from the beam  20  to extend through an aperture  28  of the plurality of apertures on the frame member  22 . An inboard portion of the retractable lug  26  is partially contained in a housing that holds a spring that biases the lug  26  laterally outward. The lugs  26  each include a tension rod  30  ( FIG. 1 ) that extends from the inboard portion the lugs  26  to a central bar  32  that is longitudinally disposed between the longitudinal beams  20 . The central bar  32  is rotatably configured with cams that engage the tension rods  30 , such that rotation of the central bar  32  moves the cams to draw the tension rods  30  inward and thereby pull the retractable lugs  26  inward to allow slidable movement of the tandem axle assembly  12  longitudinally relative to the chassis of the vehicle. 
         [0027]    As shown in  FIG. 2 , the front axle assembly  16  includes a brake assembly  34  coupled with the distal ends of the front axle  18 . Accordingly, the distal ends of the front axle  18  also include wheel assemblies  36  that are configured to be releasably engaged by the brake assemblies  34  to reduce and cease rotation of the wheel assemblies  36 . The wheel assemblies  36  include a tire for contacting a road or ground surface and, in one embodiment, a tire pressure sensor  38  for monitoring the air pressure of the tire. It is contemplated that the tires may include dual tires for increasing tire surface contact with the road surface. It is also understood that the rear axle assembly  14  ( FIG. 1 ) includes a corresponding wheel assembly  36  on the opposing side of the axle  18  that may also similarly include tire pressure sensors  38  and other related components. 
         [0028]    Referring now to  FIGS. 3 and 4 , the tandem axle assembly  12  includes a number of cross members  40  that extend substantially orthogonally between the longitudinal beams  20 . The central bar  32  that operates to retract the retractable lugs  26  from engagement with the frame member  22  ( FIG. 1A ) is rotatably coupled between the cross members  40  proximate the front axle assembly  16 . An auxiliary pneumatic cylinder  42  includes an actuation shaft that is coupled to the central bar  32  with a rotational coupling that surrounds a portion of the central bar  32  for rotating the central bar  32  upon actuation of the auxiliary pneumatic cylinder  42 . It is contemplated that alternative actuation mechanisms, such as solenoids or electric motors, may be employed to engage and disengage the plurality of lugs  26  with the apertures  28  in the frame member  22  ( FIG. 1A ). 
         [0029]    As illustrated in  FIG. 5 , a single side of the tandem axle assembly  12  is shown, although it is understood in the foregoing description that the opposing side of the tandem axle assembly  12  includes like parts, unless specified to the contrary. As shown in the illustrated embodiment, a support bracket  44  extends down from the beam  20  proximate the front axle assembly  16 . The support bracket  44  has an upper portion  46  coupled with the beam  20  and a lower portion  48  pivotally coupled with the upper portion  46 . The lower portion  48  includes a platform  50  longitudinally protruding toward the axle  18  for supporting a pneumatic actuator  52 . More specifically, the platform  50  is defined on a rearward end of the generally L-shaped lower portion  48  of the support bracket  44 . A trailing arm  54  of the front axle assembly  16  includes a first end  56  pivotably coupled with the upper portion  46  of the support bracket  44 , above the pivotal connection between the upper and lower portions  46 ,  48  of the support bracket  44 . A cylindrical shock  58  is pivotably coupled with and extends down from the longitudinal beam  20  proximate the connection with the support bracket  44  to engage the axle  18  proximate the trailing arm  54 . It is contemplated that the support bracket  44  may be a unitary bracket, an integral piece of the longitudinal beam  20 , or other conceivable geometric configurations that incorporates a lift assembly  66 . 
         [0030]    The axle  18  on the rear axle assembly  14 , as shown in  FIGS. 5 and 6 , is rotatably coupled with an intermediate portion  60  of the trailing arm  54 , between the first end  56  and a second end  62  of the trailing arm  54 , in a substantially similar manner as the front axle assembly  16 . In further similarity to the front axle assembly  16 , the axle  18  of the rear axle assembly  14  includes a sleeve for an axle shaft to rotate within, such that the intermediate portion of the trailing arm  54  couples with the sleeve of the axle  18  to permit rotation of the axle shaft at the distal ends for corresponding rotation of the wheel assemblies  36 . An air spring  64 , or ride bag, is disposed between the second end  62  of the trailing arm  54  and the longitudinal beam  20  for receiving the downward load from the tire riding on a road or ground surface and for receiving, and in some instances absorbing, an upward force on the axle  18 , such as impact forces from the tire hitting bumps on the road surface. The air springs  64  on both the front and rear axle assemblies  16 ,  14  are coupled with a substantially planar and circular surface on the second end  62  of the trailing arm  54 . The substantially planar surface on the second end  62  of the trailing arm  54  is defined by a tear-shaped plate coupled with an upper surface of the trailing arm  54  proximate the second end  62 . It is conceivable that in additional embodiments that the axle  18  and the air springs  64  may be alternatively coupled with trailing arm  54  closer to the second end  62  or the first end  56  of the trailing arm  54 . 
         [0031]    As shown in  FIG. 5 , the air spring  64  on the rear axle assembly  14 , and conceivably also on the front axle assembly  16 , includes an air pressure sensor  65  that monitors the air pressure of the corresponding air spring  64 . The air pressure sensor  65  may be used to monitor the weight of the load proximate the associated axle assembly by taking into consideration the difference in air pressure of the air spring  64  between an unloaded state and a loaded state. In addition, it is contemplated that the air springs  64  on the front and rear axle assemblies  16 ,  14  ( FIG. 5 ) may jointly include an air pressure sensor that monitors the air springs  64  of both axle assemblies. 
         [0032]    Referring now to  FIGS. 7-9 , a lift assembly  66  is generally coupled between the trailing arm  54  ( FIG. 6 ) and the longitudinal beam  20 . The lift assembly  66 , according to one embodiment, includes a pneumatic actuator  52  that is disposed between the platform  50  longitudinally protruding from the lower portion  48  of the support bracket  44  ( FIG. 5 ) and the trailing arm  54 . More specifically, the pneumatic actuator  52  includes a bearing block  68  on an upper surface of the pneumatic actuator  52 . The bearing block  68  is configured to abut a bottom surface of the trailing arm  54  between the first end  56  ( FIG. 6 ) of the trailing arm  54  and the axle  18 . A guide arm  70  is coupled with the bearing block  68  and extends to couple with the support bracket  44  at the pivotal connection between the upper and lower portions  46 ,  48  of the support bracket  44 . The pneumatic actuator  52  is adjustable with compressed air between a deflated position  72  ( FIG. 10 ) and an inflated position  74  ( FIG. 11 ). In the deflated position  72 , as also shown in  FIG. 8 , the bearing block  68  may be out of contact with the trailing arm  54  and the tire on the associated axle  18  is in load bearing contact with the road surface, defining the ground engagement position  76  ( FIG. 10 ), of the axle  18 , as further described below. In the inflated position  74 , the pneumatic actuator  52  is inflated to raise upward from the platform  50  on the support bracket  44  and put the bearing block  68  into contact with the trailing arm  54 , ultimately raising the axle  18  to a lifted position  78  ( FIG. 11 ) to elevate the tire from the road surface. When the pneumatic actuator  52  moves to the inflated position  74 , the guide arm rotates about the pivotal connection between the upper and lower portions of the support bracket  44 . 
         [0033]    As further illustrated in  FIG. 10 , one embodiment of the lift assembly  66  has the front axle assembly  16  in the ground engagement position  76  and shows the lifted position  78  in fragmented lines. In the ground engagement position  76 , the air spring  64  of the front axle assembly  16  is pressurized to receive and absorb upward forces from the front axle  18  ( FIG. 7 ). As illustrated in  FIG. 11 , the lift assembly  66  is activated to place the front axle  18  in the lifted position  78 , also showing the ground engagement position  76  in fragmented lines. In the lifted position  78 , the air spring  64  of the front axle assembly  16  has air released to depressurize and to allow the axle  18  to be moved toward the longitudinal beam  20  a distance adapted to raise the associated tire on the front axle  18  away from the road or ground surface. The lift assembly  66  may be actuated between the ground engagement position  76  and the lifted position  78 , adjusting the pneumatic actuator  52  ( FIG. 9 ) between the deflated and inflated positions  72 ,  74 , respectively, by operating the air system of the vehicle manually or automatically. Automatic actuation of the lift assembly  66  may be selected by a user, whereby a controller on the vehicle operates the lift assembly  66  using a first automatic system, a second automatic system, or other conceivable automatic actuation systems. 
         [0034]    The first automatic actuation system, as illustrated in  FIG. 12 , is operated by receiving input from the air pressure sensor  65  on the air springs  64  of the rear axle assembly  14 . Specifically, after the system is powered up and pressurized air is available to operate the lift assembly  66 , the system first checks to see if the parking brake of the vehicle is released. If the parking brake is released, then the system determines that the vehicle is being operated. It is contemplated that other indicators may be used to determine if the vehicle is being operated, such as a speed sensor, an ignition sensor, a GPS device, or other conceivable sensors or indications. Upon determination that the vehicle is being operated, namely the parking brake is released, the air pressure is monitored in at least one of the air spring  64  of the rear axle assembly  14  by the air pressure sensors  65 . It would also be possible to alternatively or additionally monitor air springs  64  on the front axle assembly  16 . 
         [0035]    As further shown in  FIG. 12 , when the lift assembly  66  is in the deflated position  72 , and the front axle  18  is in the ground engagement position, such that the air spring  64  of the front axle assembly  16  is receiving upward forces from the axle  18 , the lift assembly  66  will automatically move the front axle  18  to the retracted position by inflating the pneumatic actuator  52  to the inflated position  74  when the air pressure sensed by the pressure sensor  65  on the air spring  64  of the rear axle assembly  14  is below a lower threshold level. The lower threshold level is configured to be a pressure level that would indicate the smallest payload weight that is best suited to be carried with both the front and rear axles  18  supported on the ground. In other words, having an air pressure below the lower threshold level is indicative of a payload weight acceptable for the rear axle to support without the need to disperse the weight between the front and rear axles. Similarly, when lift assembly  66  is in the inflated position  74 , or otherwise deployed, and the front axle is in the lifted position, such that the air spring  64  on the front axle assembly  16  is not receiving upward forces from the axle  18 , the lift assembly  66  will automatically move the front axle  18  to the ground engagement position  76  by releasing air in the pneumatic actuator  52  when the air pressure on the air spring  64  of the rear axle assembly  14  is above an upper threshold level. Having an air pressure above the upper threshold level is indicative of a payload weight large enough to exceed the suggested carrying capacity of the rear axle alone, and thereby require both the front and rear axles to disperse the weight. The difference between the upper and lower threshold levels may be negligible, such that they can be referred to generally as a threshold level; however the purpose of the difference is to prevent actuation of axle lift assembly due to minor variations in load weight that may be due to errors in the sensor  65  measurements, shifts in the load, bumps on the road, or other conditions that would cause minor variations in the sensor measurements, as generally understood by one having ordinary skill in the art. The first actuation system also continues to monitor the parking brake to power down the automatic actuation system when the parking brake is engaged. It is conceivable that the actuation system may be disabled manually by an operator. 
         [0036]    As shown in  FIG. 13 , the second automatic actuation system is alternatively operated with additional input from the tire pressure sensors  38 . Again, the second actuation system first checks to see if the parking brake is released to determine whether the vehicle is being operated. When the parking brake is released, the tire pressure on the rear axle assembly  14  is monitored with the tire pressure sensors  38 . If the tire pressure is outside an acceptable tire pressure range, as generally understood in the art as a range that causes damage to the tires or presents a risk of tire failure, the system does not allow the lift assembly  66  to automatically move the front axle  18  to the lifted position  78 . Similarly, if the front axle  18  is already in the lifted position  78  and the tire pressure sensors  38  sense the tire pressure on the rear axle assembly  14  to be outside the acceptable tire pressure range, the front axle  18  is move to the ground engagement position  76  by releasing air from the pneumatic actuator  52 . Therefore, if the vehicle  12  is operating solely on the rear axle  18  with low tire pressure, the front axle  18  will lower to the ground engagement position  76  to provide additional support to the vehicle  12  and disable automatic actuation of the lift assembly  66  until the tire pressure returns within the acceptable tire pressure range. Otherwise, if the tire pressure is acceptable, the system monitors the air pressure of the air springs  64  with the air pressure sensors  65 , similar to the first automatic actuation system, to determine, in view of the threshold level, whether the lift assembly  66  should move the front axle  18  between the ground engagement position and the lifted position. It is also contemplated that the tire pressure sensors  38  may be alternatively monitored in a similar manner to the air pressure sensors  65  to determine the payload weight for actuating the lift assembly  66  between the deflated and inflated positions. 
         [0037]    It will be understood by one having ordinary skill in the art that construction of the described invention and other components is not limited to any specific material. Other exemplary embodiments of the invention disclosed herein may be formed from a wide variety of materials, unless described otherwise herein. 
         [0038]    For purposes of this disclosure, the term “coupled” (in all of its forms, couple, coupling, coupled, etc.) generally means the joining of two components (electrical or mechanical) directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally formed as a single unitary body with one another or with the two components. Such joining may be permanent in nature or may be removable or releasable in nature unless otherwise stated. 
         [0039]    It is also important to note that the construction and arrangement of the elements of the invention as shown in the exemplary embodiments is illustrative only. Although only a few embodiments of the present innovations have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements shown as multiple parts may be integrally formed, the operation of the interfaces may be reversed or otherwise varied, the length or width of the structures and/or members or connector or other elements of the system may be varied, the nature or number of adjustment positions provided between the elements may be varied. It should be noted that the elements and/or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability, in any of a wide variety of colors, textures, and combinations. Accordingly, all such modifications are intended to be included within the scope of the present innovations. Other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the desired and other exemplary embodiments without departing from the spirit of the present innovations. 
         [0040]    It will be understood that any described processes or steps within described processes may be combined with other disclosed processes or steps to form structures within the scope of the present invention. The exemplary structures and processes disclosed herein are for illustrative purposes and are not to be construed as limiting. 
         [0041]    It is also to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.