Patent Application
20110031713
The current disclosure is directed to the design and construction of rod end mounting bushings and the use of a pair of such bushings as part of a rod end connection in a suspension linkage. In the exemplary embodiment which is disclosed, the rod end mounting bushings are used as a matched pair in cooperation with a spherical joint.
Spherical joints, such as on rod ends as a part of suspension linkages, are typically connected to a vehicle superstructure by the use of a clevis arrangement of two spaced-apart plates. While the two clevis plates are substantially parallel to each other, they are typically welded into position with an angle which is intended to generally correspond to the angle of the rod which is received between the two clevis plates. Considering the location for the two clevis plates and the confined working space, the welding task can be challenging and it may be difficult to (accurately) achieve the desired angle. If the two clevis plates are not set (i.e., welded in position) with an angle which is fairly close to the rod angle, proper alignment and proper installation become design and construction issues for the rod end assembly. Depending on the structural specifics and vehicle design, these design and construction issues can be significant. While there is some range of motion tolerance for the spherical joint, the greater the clevis plate misalignment, the more this range of motion tolerance is used up.
As used herein, the conventional X-axis direction corresponds to the longitudinal centerline of the vehicle which has the referenced suspension linkage and uses the disclosed rod end mounting bushings. The Y-axis direction is perpendicular to the X-axis direction and, as used herein, extends laterally through the vehicle from side to side. Accordingly, when describing that the two clevis plates are set at an angle, and similarly in describing the suspension linkage rod axis or longitudinal centerline being at an angle, this is a direction which is not parallel to either the X-axis direction or to the Y-axis direction, as those are defined herein.
In a heavy duty suspension application, the clevis connection typically consists of thick plates of steel, spaced apart, so as to receive the spherical joint therebetween. These thick plates do not bend when the securing bolt is tightened. Further, in any design modification, refurbishment, or reconstruction, these thick plates may warp during welding. The angular alignment issues and any warping problems can combine with the inability to bend, thereby making proper bolt hole alignment difficult. These factors are seen as the primary contributors in making proper installation/assembly of the spherical joint more difficult. Modification or reconstruction (refurbishment) work is made more time consuming when the thick plates are not properly aligned (hole alignment) and have to be further reworked, typically by on-site machining. As noted above, if the clevis plates are misaligned such that their angle does not closely correspond to the rod axis angle, some (or all) of the range of motion tolerance of the spherical joint can be used up.
If all of the cooperating structures are aligned within the desired tolerances, then the two clevis plates define a clearance space therebetween which receives the rod end (spherical joint) misalignment spacers, and mounting hardware (washers). Bolt holes in the clevis plates would also be generally aligned for receipt of the securing (shoulder) bolt which extends through the spherical joint.
One specific application where the thick plate alignment problem can be seen is as part of an axle suspension system of a military vehicle. Typically, the axle is supported from the frame by a four-bar linkage type of suspension including a V-shaped upper link. The apex of the upper link is secured to the frame above the axle by a spherical (ball) joint connection to permit limited universal movement of the upper link relative to the axle. Opposite ends of the upper link are connected to the referenced clevis connections which in turn are welded or otherwise attached to the superstructure of the vehicle.
The thick plate (clevis arrangement) alignment issue, as discussed above, is addressed by the present disclosure and by its exemplary embodiment by the use of rod end mounting bushings. A pair of mounting bushings is used with the assembly of each spherical joint (i.e., the rod end) as part of its overall connection to the pair of clevis plates or to another similar support structure. The disclosed mounting bushings permit use of a support structure in lieu of welding on clevis plates to that support structure. The disclosed rod end mounting bushings offer a simple and effective way to connect various rod ends to a superstructure, whether or not clevis plates are being used. If clevis plates are used for the rod end connection, the angular alignment of those plates relative to the rod axis is not as critical. In part this is why a portion of the vehicle superstructure can be used in lieu of using a pair of clevis plates. The various fabrication, design, and use options disclosed herein provide greater overall versatility in a more efficient and cost effective manner, one of the benefits of the disclosed mounting bushings.
A rod end mounting bushing for use in a connection assembly is disclosed. The rod end mounting bushing has a generally cylindrical body with a longitudinal axis line extending through the body and with opposite end faces wherein each end face has a defining geometric plane. Each geometric plane is constructed and arranged at an angle of incline relative to the longitudinal axis line of the generally cylindrical body. The body defines a through aperture which extends from one end face to the opposite end face. This through aperture has a longitudinal axis line which is substantially perpendicular to at least one of the end faces.
One object of the present disclosure is to describe an improved rod end mounting bushing for use in a connection assembly.
For the purposes of promoting an understanding of the disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the illustrated device and its use, and such further applications of the principles of the disclosure as illustrated therein being contemplated as would normally occur to one skilled in the art to which the disclosure relates.
Referring to
Although not actually “supplied” as part of the connection assembly 20, the two receiving members 30 and 31 typically have a clevis configuration and represent those portions of the structure (superstructure of the vehicle) to which the rod end 21 of the rod (suspension linkage) 22 is connected. A clearance aperture 37 and 38 in each receiving member 30 and 31, respectively, is provided for receipt of a rod end mounting bushing, as further described herein. These two spaced-apart receiving members 30 and 31 create a clevis plate structure as illustrated in
The relevant point to be made regarding the two receiving members 30 and 31 is that they represent the structural support portion of the vehicle to which rod end 21 is connected, the connection is made and completed in the manner illustrated in
As explained in the Background, it is expected that there will be some degree of misalignment or warpage of the two clevis plates, such that the geometric planes may not be precisely parallel to each other. It is also likely that these geometric planes will not be set at the desired angle. This outcome, albeit perhaps in varying degrees, is expected, whether utilizing an extended clevis construction, as illustrated in
Each receiving member 30 and 31 is constructed and arranged with a through aperture 37 and 38, respectively. Without the benefit of the disclosed alignment bushings 42 and 43, it is important to try and have apertures 37 and 38 in some reasonable degree of axial alignment for proper and efficient connection of the rod end 21 and the passage of shoulder bolt 24. However, by using the pair of alignment bushings 42 and 43, the through apertures 37 and 38 are intentionally not constructed and arranged to be coaxial. Instead, the axes of these through apertures 37 and 38 are shifted along a common horizontal line relative to one another so as to purposefully create an angled or skewed alignment. The amount of aperture offset between the axes of apertures 37 and 38 helps to determine the gap between the facing surfaces of the alignment bushings 42 and 43 when the connection is fully assembled. As would be understood, each through aperture 37 and 38 has a defining axis line and while those axis lines are “aligned” in that they are on the same horizontal plane, they are shifted relative to one another by a distance which is determined in part by the angle of the longitudinal centerline 22a. The use of the pair of alignment bushings 42 and 43 also affords greater versatility in terms of the degree of parallelism of the receiving members 30 and 31 which is required and the degree of coincidence with the angle of the longitudinal centerline 22a relative to the X-axis and to the Y-axis of the vehicle.
There are a number of factors which affect the ability to precisely machine apertures 37 and 38 into corresponding receiving members 30 and 31, respectively. One consideration is whether the machining of the apertures 37 and 38 will be performed prior to assembly of the two receiving members to the vehicle superstructure. Machining the two apertures in the receiving members prior to welding the receiving members to the superstructure allows more accurate initial machining. However, some degree of alignment is later lost due to the warpage which results from the welding step. Machining the apertures 37 and 38 into the corresponding receiving members prior to assembly is also the most efficient from a machining perspective. An alternative is to machine the apertures 37 and 38 into the receiving members after assembly of the receiving members (welding) to the vehicle superstructure. While any warpage issue due to welding may be minimized by this approach, the size of the receiving members, the materials which are used, and the overall environment (an issue of clearance and accessibility) provide additional difficulties limiting one's ability to precisely machine these apertures 37 and 38 with the necessary axial alignment. While it may be possible to do so, time and cost are issues. The time which it takes to perform this machining step after assembly, and the resultant cost, are considered disadvantages.
The concerns regarding the size, location, and alignment of apertures 37 and 38 takes on a high priority for connection assemblies which do not have the benefit of using alignment bushings 42 and 43. When alignment bushings 42 and 43 are used as a part of the rod end connection, as described herein, there is a type of “self-alignment” which takes place. One design reality from the use of alignment bushings 42 and 43 is that apertures 37 and 38 do not have to be located quite as accurately or precisely if they are slightly oversized. The primary design consideration is ensuring that the axial centerlines or bore axes of apertures 37 and 38 are offset from each other the appropriate amount to allow the rod end 21 to be clamped. This clamping is performed by the combination of alignment bushings 42 and 43 (their inwardly directed faces) and (if used) spacers 44 and 45. If spacers 44 and 45 are not used in the connection assembly, then the clamping up against the rod end 21 is by only the two bushings 42 and 43 (using the associated connection hardware).
Although the
Regardless of the approach selected for receiving members 30 and 31, when the alignment bushings 42 and 43 are used as disclosed herein, some degree of axial “misalignment” of the two through apertures 37 and 38 is required. The use of “misalignment” is intended to indicate that the axial centerlines of apertures 37 and 38 are not coaxial. However, when alignment bushings 42 and 43 are used, this lack of alignment is intentional. Not only is the non-alignment of centerlines intentional, the extent or degree of shift is selected based in part on the angularity of rod centerline 22a. Without the use and benefit of alignment bushings 42 and 43, the overall alignment concerns for the rod end connection are further complicated when the receiving members 30 and 31 (i.e., the clevis plates) must be installed at an angle. As described herein, it is anticipated that there will be alignment issues and problems relating to prior art rod end connections. Connection assembly 20 fully addresses those issues and problems. As such, the use of connection assembly 20 enables the proper installation of rod end 21 to the structural receiving members 30 and 31. This is accomplished without the need to spend additional time or incur additional costs in reworking of the receiving members 30 and 31. Connection assembly 20 is fully applicable to the
The connection assembly 20 includes fastener 24, the two alignment or rod end mounting bushings 42 and 43 (see
As noted, each rod end mounting bushing 42 and 43 provides what could be called a “self-aligning” capability to connection assembly 20. This capability will be clear from the structural description of each bushing 42 and 43 which follows, combined with an understanding of the configuration of the receiving members 30 and 31 and the manner in which each through aperture 37 and 38 is machined into its corresponding receiving member 30 and 31. The disclosed mounting bushings 42 and 43 are suitable for use in the manner described relative to the
Referring to
Each end face 50 and 51 is a substantially flat surface and defines a corresponding geometric plane 50a and 51a, respectively. The flat surfaces of the end faces 50 and 51 are substantially parallel to each other and are constructed and arranged with an angle of incline relative to the longitudinal centerline 53. In the
With further reference to
Referring now to
The outside diameter size and shape of body 49 and the inside diameter size and shape of through aperture 37 are such that there is a slip fit of the bushing 42 within the receiving member 30. This clearance is minimal so as to limit any wobble, yet still enable the bushing 42 to be able to be turned within the receiving member 30. The same is true for bushing 43, receiving member 31, and through aperture 38. This turning motion allows everything to be aligned (and still loose) prior to welding each bushing in position within its corresponding receiving member 30 and 31. There is essentially a single coaxial orientation for the bushing apertures 52 which permits the aligned insertion of bolt 24. The connection requirements for connection assembly 20 require the fastener 24 (bolt) to extend through and to be aligned with bushing 42, spacer 44, rod end 21, spacer 45 and bushing 43. The two spacers and the rod end are free floating so no axial alignment issues are presented with those components. However, each bushing 42 and 43 is ultimately fixed in position within its corresponding receiving member 30 and 31, respectively, preferably by welding. Therefore, a preliminary “check” of the entire connection assembly is made by loosely putting everything together and turning the bushings to find their bolt alignment orientation. At this point, each bushing 42 and 43 is welded into position within its corresponding receiving member 30 and 31, respectively.
If the receiving members 30 and 31 have experienced any of the misalignment or warpage issues discussed earlier, then without the benefit of bushings 42 and 43, some adjustment, rework, or realignment would be necessary. Bushings 42 and 43 enable a properly aligned connection without having to incur the time or expense of reworking the receiving members 30 and 31. Instead, by simply selecting the appropriate bushing 42 and 43, and by using the correct aperture offset, the fastener-receiving apertures 52 are easily aligned and provide an acceptable arrangement for connection assembly 20 for receiving rod end 21. The “appropriate” bushings means bushings which have an angle of incline which is selected based in part on the angle of the longitudinal centerline 22a and in part on the configuration and spacing of the receiving members 30 and 31. These variables are either known or can be determined. The data is then processed to decide on the aperture offset and the angle of incline for the bushings.
After the apertures 37 and 38 are machined into the receiving members 30 and 31, respectively, with the desired axial offset and after all other dimensional information is gathered and after the appropriate bushings are selected, the connection assembly is loosely assembled as a way to check and verify the final alignment. In order to do so, the bushings are turned within their corresponding apertures in order to properly align the corresponding bolt holes. There is only one coaxial orientation for each of the two bushings which results in a precise bolt hole alignment. Once this alignment is set, the bushings are secured in position within the receiving members, preferably by welding. The turning of the bushings so as to achieve bolt hole alignment is a type of “self-alignment” which is unique. The use of bushings with an inclined angle and the intentional offset of the apertures as tied to the angle of the longitudinal centerline 22a are also unique features.
It is envisioned that a range of bushing options would be desirable, depending on the extent or magnitude of the angle of the longitudinal centerline 22a. The bushing options would also depend to some extent on the location and relationship of receiving members 30 and 31 and the location of apertures 37 and 38. When the rod angle to be accommodated is greater, a greater angle of incline 55 would be preferred. When the rod angle to be accommodated is smaller, a smaller angle of incline would be preferred. While it is anticipated that several “standard” bushings would be offered with a graduated range of angles of incline, only two such variations are illustrated herein. One option with a graduated range of angles would be to have “standard” bushings in three to five degree increments, beginning with a low or small angle of perhaps 2 degrees and extending on up to 45 degrees or perhaps slightly higher. It is also contemplated that the limited clearance of the various receiving bores and apertures for fastener 24 would provide some degree of adjustment for any misalignment and thus a single bushing might be suitable for a limited range of degrees of misalignment. Using slightly oversized apertures 37 and 38 would also introduce some added clearance. The two variations illustrated herein include bushings that are considered to be closer to the lower end point of the overall range and to a mid-range angle of incline. Bushing 42 which is illustrated in
The construction and arrangement of the disclosed structures removes the need to measure or fit any parts prior to final assembly. There is no rework, no modifications, and no machining required prior to final assembly. The disclosed self-alignment capability of the rod end mounting bushings, as disclosed herein as part of the overall connection assembly, precludes the need to check any orientations or alignments prior to final assembly.
While the preferred embodiment of the invention has been illustrated and described in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that all changes and modifications that come within the spirit of the invention are desired to be protected.
