Patent Publication Number: US-2023133284-A1

Title: Rotary torque input fixture for testing a solid axle in a road simulation test

Description:
FIELD 
     The present disclosure relates a rotary torque input fixture for testing a solid axle during a road simulation test. 
     BACKGROUND 
     When a vehicle with a solid axle suspension undergoes an acceleration event on the road, a phenomenon within the axle commonly known as axle windup occurs. Axle windup produces a torsional strain within the axle tubes, along with loads in other components of the suspension such as control arms and leaf springs. During a road test simulation, engineers seek to reproduce these loads, including axle windup, in a lab environment. In this regard, during the road test simulation, inputs are applied to the suspension to move it in such a way that the same forces and displacement as measured on the road are fully reproduced in the lab in a controlled environment. 
     Currently, in order to reproduce axle windup during the road test simulation, the axle must be attached to a fixture with adapters that may require the axle to be modified before testing. For example, in order to fit the adapters that attach the axle to the fixture, the differential cover and ring gear of the axle may require removal. This is undesirable in that removal of these components from the axle can affect the mechanical properties of the axle and, therefore, affect the validity of the road test simulation. 
     In addition, the mechanism that applies torque to the axle adds un-sprung mass to the axle assembly, which can create unwanted inertial loads into the axle that can adversely affect the test results. More particularly, a linear actuator is currently used to input torque to the axle. The linear actuator moves a pair of arms that attached to opposing sides of the axle in equal and opposite directions to convert the linear motion to torsional motion. Unfortunately, the manner in which the pair of arms are connected to the axle result in a load path that does not match what is experienced during real time driving conditions, which can introduce a source of error into the test results. 
     SUMMARY 
     According to a first aspect of the present disclosure, there is provided a road simulation test system for testing torsional strain input to an axle assembly having an input shaft and a suspension system. The test system includes a torque input module configured to apply rotary torque to the axle assembly. The torque input module includes a rotary actuator, a torsional load cell, a drive shaft connection portion, and a controller in communication with the rotary actuator and the torsional load cell, wherein upon receipt of an instruction from the controller, the rotary actuator is configured to rotate the input shaft to apply the rotary torque to the axle assembly, and as the rotary actuator rotates the input shaft, a signal indicative of a torsional load is communicated by the torsional load cell to the controller to monitor the rotary torque applied to the axle assembly. 
     According to the first aspect, the torque input module further includes an angular displacement transducer attached to the rotary actuator and in communication with the controller, wherein the angular displacement transducer is configured to transmit a signal indicative of an angular displacement applied to the input shaft of the axle assembly. 
     According to the first aspect, the drive shaft connection portion includes a drive shaft having a proximate end attached to the rotary actuator, and a distal end attached to the input shaft of the axle assembly. 
     According to the first aspect, the drive shaft includes a first section attached to the rotary actuator and a second section attached to the input shaft, wherein the first section and second section are telescopically movable relative to each other. 
     According to the first aspect, the first section and second sections each include a plurality of axially extending splines that are configured to mate with each other to ensure rotation of the drive shaft when the first and second sections are mated to each other. 
     According to the first aspect, the rotary actuator includes a spindle that is attached to a recess formed in a first end of the torsional load cell that is configured for receipt of the spindle, and the first section of the drive shaft is attached a second end of the torsional load cell. 
     According to the first aspect, the test system also includes a support structure for supporting the axle assembly and the torque input module. 
     According to the first aspect, the support structure includes a pair of stanchions that support a backbone, and the axle assembly and the torque input module are attached to the backbone. 
     According to the first aspect, the support structure includes support jig that attaches the axle assembly to the backbone, wherein the support jig includes a plurality of couplings that attach components of the suspension system to the support jig. 
     According to the first aspect, the support structure includes a support truss that attaches the torque input module to the backbone. 
     According to the first aspect, the torque input module is attached to a mounting frame that is attached to the support truss. 
     According to a second aspect of the present disclosure, there is provided a method for testing torsional strain input to an axle assembly having an input shaft and a suspension system. The method includes applying rotary torque to the axle assembly using a torque input module including a rotary actuator, a torsional load cell, and a drive shaft connection portion, wherein the rotary actuator rotates the input shaft to apply the rotary torque to the axle assembly; and monitoring a torsional load applied to the axle assembly with the torsional load cell. 
     According to the second aspect, the method also includes monitoring an angular displacement applied to the input shaft of the axle assembly using an angular displacement transducer that is part of the torque input module. 
     According to the second aspect, the drive shaft connection portion includes a drive shaft having a proximate end attached to the rotary actuator, and a distal end attached to the input shaft of the axle assembly. 
     According to the second aspect, the drive shaft includes a first section attached to the rotary actuator and a second section attached to the input shaft, wherein the first section and the second section are telescopically movable relative to each other. 
     According to the second aspect, the first section and second section each include a plurality of axially extending splines that are configured to mate with each other to ensure rotation of the drive shaft when the first and second sections are mated to each other. 
     According to the second aspect, the method also includes attaching the axle assembly and the torque input module to a support structure. 
     According to the second aspect, the support structure includes support jig that attaches the axle assembly to the backbone, and the method further comprises attaching components of the suspension system to the support jig. 
     Further areas of applicability of the teachings of the present disclosure will become apparent from the detailed description, claims and the drawings provided hereinafter, wherein like reference numerals refer to like features throughout the several views of the drawings. It should be understood that the detailed description, including disclosed embodiments and drawings referenced therein, are merely exemplary in nature intended for purposes of illustration only and are not intended to limit the scope of the present disclosure, its application or uses. Thus, variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an isometric perspective view of a testing system for inputting a rotary torque to an axle assembly according to a principle of the present disclosure; 
         FIG.  2    is a side perspective view of the testing system illustrated in  FIG.  1   ; 
         FIG.  3    is a bottom perspective view of the testing system illustrated in  FIG.  1   ; 
         FIG.  4    is a perspective view of a torque input module that is part of the testing system illustrated in  FIG.  1   ; 
         FIG.  5    is a cross-sectional view of the torque input module along line  5 - 5  of  FIG.  4   ; and 
         FIGS.  6  and  7    illustrate a drive shaft of the torque input module illustrated in  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
       FIGS.  1 - 5    illustrate a testing system  10  for inputting a rotary torque to an axle assembly  12  according to a principle of the present disclosure. System  10  includes a support structure  14  including a plurality of stanchions  16  that support a backbone  18  that is fixed to stanchions  16 , and configured to suspend and support axle assembly  12  during torsional testing thereof. Support structure  14  also includes a support jig  20  that is configured to attach axle assembly  12  to backbone  18 , and configured for attachment to various features of axle assembly  12 . Stanchions  16  and jig  20  may be formed of rigid materials such as steel, aluminum, or some other type of rigid material that are configured to support and suspend axle assembly  12 . 
     Axle assembly  12  includes an axle  22  including a differential housing  24  that houses various gears (not illustrated), a pair of axle tubes  26  that each have a hub  28  and brake assembly  30  attached to the differential housing  24 , and an input shaft (of which only a input shaft coupling  29  is illustrated) that is attached to the gears within differential housing  24 . In addition, axle assembly  12  includes a suspension system  13  including, but not limited to, a pair of coil springs  32 , a pair of leaf spring assemblies  34 , and a pair of dampers  36 . In a vehicle, the coil springs  32 , leaf spring assemblies  34 , and dampers  36  are each attached to the axle  22  and also attached to a vehicle frame (not illustrated) or body (not illustrated). Inasmuch as axle assembly  12  is not part of a vehicle while located in test system  10 , support jig  20  includes various flanges  38  and couplings  40  that are shaped and configured like those found in a vehicle for connecting to coil springs  32 , leaf spring assemblies  34 , and dampers  36  such that when axle assembly  12  is being tested, these features will function in the same manner as when part of a vehicle. 
     Support jig  20  may be fixed to backbone  18 , or translatable along a length of backbone  18 . In either case, support jig  20  includes a pair of rails  42  that extend along and are configured to be connected to backbone  18  by mounting fixtures  44 . Rails  42  are connected to each other by a pair of plates  46 . Fixtures  44  may include apertures  45  formed therein to permit jig  20  and axle assembly  12  to be lifted and attached to backbone  18  using a crane, winch, or some other type of lifting device (not shown). Rails  42  function in a manner similar to a vehicle frame (not shown), and include the above-noted flanges  38  and couplings  40  for attaching axle assembly  12  thereto. 
     System  10  also includes, in accordance with a principle of the present disclosure, a rotary torque input module  48 . Module  48  includes a mounting frame  50  that is configured to be attached and detached from a support truss  52 . Support truss  52  includes a pair of beams  54  that extend along backbone  18 . Beams  54  are each coupled to a corresponding upstanding support plate  56  that extends in parallel with beams  54 , and is configured to be attached to backbone  18  using fasteners  57 . A mounting plate  58  is connected to and extends between the upstanding support plates  56 , which is configured to connected to mounting frame  50  by welding or some other attachment mechanism. 
     Mounting frame  50  includes a pair of planar support members  60 . A plurality of support girders  62  extend upward form planar support members  60  that are attached to mounting plate  58 . Support girders  62  support a rotary torque input assembly  64  that is configured to connect to input shaft coupling  29  of axle assembly  12 . Rotary torque input assembly  64  is connected to support girders  62  using fasteners  66  or some other type of attachment mechanism. 
     As best shown in  FIGS.  4  and  5   , rotary torque input assembly  64  includes an angular displacement transducer  68 , a rotary actuator  70 , a torsional load cell  72 , drive shaft connection portion  74 , and controller  76 . Rotary actuator  70  may any type of actuator known to one skilled in the art, including hydraulic actuators and electric actuators. Rotary actuator  70  is controlled by controller  76 , and is configured to rotate drive shaft connection portion  74 , which in turn rotates input shaft  28  that is attached to differential  24 . Angular displacement transducer  68  and torsional load cell  72  communicate with controller  76 . Thus, as rotary actuator  70  rotates drive shaft connection portion  74  and input shaft  28 , signals that are indicative of the angular displacement of input shaft  28  and the torsional load experienced by axle assembly  12  may be communicated by angular displacement transducer  68  and torsional load cell  72 , respectively, to controller  76  to monitor the rotational torque applied to axle assembly  12  by input assembly  64 . 
     As best shown in  FIG.  5   , rotary actuator  70  includes a spindle  78  that is connected to torsional load cell  72 . In this regard, load cell  72  includes a first end  80  having a recess  82  configured for receipt of spindle  78  and an opposite second end  84  that is configured for connection with drive shaft connection portion  74 . Drive shaft connection portion  74  includes a housing  86  that is fixed to side beams  88  that are fixed to support girders  62 . Housing  86  additionally includes a sleeve  90  that acts as a bearing surface for a first section  92  of a drive shaft  94  rotatably supported within housing  86 . First section  92  of drive shaft  94  includes a proximate end  96  connected to second end  84  of load cell  72  and a distal end  98  having a coupling  100  that extends outward from housing  86  in a direction toward input shaft  28  of axle assembly  12 . 
     Referring to  FIGS.  6  and  7   , a second section  102  of drive shaft  94  is illustrated. Second section  102  is a two-piece structure including an input end  104  and an output end  106 , where output end  106  is capable of telescopically moving relative to input end  104  for jounce and rebound purposes during testing. Input end  104  includes a first universal joint  108  configured to attach to coupling  100  of first section  92 . Input and output ends  104  and  106  are each cylindrical tubes having a plurality of axially extending splines  110  that are configured to mate with each outer to ensure rotation thereof when mated to each other. Output end  106  includes a second universal joint  112  that is configured to connect to input shaft coupling  29 . While not required by the present disclosure, it should be noted that if second section  102  is not long enough to reach input shaft coupling  29  attached to axle assembly  12 , an extension shaft  114  may be used that couples output end  106  to input shaft coupling  29 . In this regard, extension shaft  114  may include a third universal joint  116  that attaches to second universal joint  112  and a coupling  118  that is configured to mate with input shaft coupling  29 . 
     Upon receipt of an instruction received from controller  76 , actuator  70  will rotate load cell  72 , drive shaft  94 , and input coupling  29  to drive the gears (not illustrated) within axle assembly  12 . Thus, rotary torque input assembly  64  inputs torsional loads into axle assembly  12  through an axle pinion (not shown) of the axle assembly  12  connected to input coupling  29 , in a similar manner as would occur in a vehicle. As a result, no modifications need to be made to axle assembly  12  to test the axle assembly  12  (i.e., the differential cover and ring gear of the axle do not need to be removed), and the torsional load that is applied to the axle assembly  12  may match what is experienced during real time driving conditions such that no sources of error are introduced into the test results like when a linear actuator is used. 
     It is important to note that the input assembly  64  does not spin the axle assembly  12  in a manner like what would occur while driving. Rather, the torsional loads applied by input assembly  64  are input in a semi-static state. This is because the hubs  28  of axle assembly  12  are constrained by a spindle-coupled road test simulation machine (not illustrated), which stops hubs  28  from freely rotating. Notwithstanding, the resistance provided by the constrained hubs  28  allow the input assembly  64  to generate axle twist loads within the suspension system  13  and axle tubes  26  when the torsional load is input to the axle assembly  12  that may be monitored by angular displacement transducer  68  and torsional load cell  72  that communicate with controller  76 . Thus, as rotary actuator  70  inputs rotary loads to axle assembly  12 , signals that are indicative of the angular displacement and the torsional load experienced by axle assembly  12  may be communicated by angular displacement transducer  68  and torsional load cell  72 , respectively, to controller  76  to monitor the rotational torque applied to axle assembly  12  by input assembly  64 . 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.