Patent Application
20200115860
The present disclosure relates generally to an extendable screed assembly for a paving machine, and more particularly to a sliding support system that allows for adjustment of the screed extension portion of the screed assembly.
A paving machine, such as an asphalt paver, is generally a self-propelled machine designed to receive, convey, distribute, and partially compact paving material, such as asphalt. Typically, the paving machine receives the paving material in a hopper positioned at the front of the machine, conveys the paving material from the hopper to the rear of the machine with parallel slat conveyors, distributes the paving material along a desired width, and compacts the paving material into a mat with a screed. The width of the screed, which may be adjustable, typically defines the capable paving width of a particular paving machine. More specifically, some paving machines include screed portions that are extendible and retractable using hydraulic actuators or other such actuating assemblies. As a result, some paving machines are able to adjust the screed in a substantially lateral direction to increase and/or decrease the paving width, as desired. Mechanical extensions, or screed extensions, may also be utilized for increasing the paving width provided by the base screed.
The hydraulic, or other such, actuating assemblies coupled to the screed are tasked with extending and retracting the screed extension portion to the desired screed width. To facilitate adjustment of the screed extension portion, the actuating assembly includes a number of bushings and/or bearings that work with the hydraulic actuators during operation of the paving machine. Once the screed is in an extended position the actuating assemblies may be further required to provide support to minimize uncontrolled and undesired movement of the screed extension portion. Oftentimes, the bushings, bearings and other actuating assembly components are numerous and difficult to access. Thus, adjustment of an extension mechanism that is coupled to a screed extension portion, particularly when conducted in the field, can be difficult, time-consuming, costly, and may require equipment that is not readily available.
U.S. Pat. No. 4,502.813 to Hojberg, (hereinafter the '813 patent), teaches an asphalt laying machine that includes a rear body having a centrally placed main screed and two side screeds, one on either side of the main screed. The '813 patent further teaches the main screed having a rigid first frame secured to arms that extend rearward in relation to the first frame with the purpose of guiding and carrying a second rigid frame of the side screeds so as to make the side screeds displaceable in parallel with and immediately behind the main screed. Furthermore, the second frame is attached to one or more smooth shafts adapted to slide in associated bushings at the rearward ends of the arms and hydraulic means may be used for displacing the second frame relative to the first frame to positions between an outer position where an asphalt course laid has a maximum width and an inner position where the asphalt course laid has a minimum width.
The present disclosure is directed to improving the state of the art set forth above.
In one aspect of the disclosure, a screed assembly for a paving machine adjustable between a first screed width and a second screed width is disclosed. The screed assembly may include a main screed portion, including a screed frame having a main deflector and a screed side plate coupled thereto. Furthermore, the screed assembly may have a screed extension portion including a screed extension portion frame, the screed extension portion being in a laterally exterior position with respect to the main screed portion. Moreover, a screed extension tube may be operably coupled to the screed frame and the screed extension portion frame, the screed extension tube configured to adjust the screed extension portion between the first screed width and the second screed width. Additionally, the screed assembly may include an extension tube support mechanism for supporting the screed extension tube when the screed assembly is adjusted between the first screed width and the second screed width. The extension tube support mechanism may include a bushing that circumferentially surrounding the screed extension tube and disposed within a bushing recess defined in the screed extension portion frame. Moreover, the extension tube support mechanism may further include a retainer ring that circumferentially surrounds and is in direct contact with at least a portion of the bushing, wherein the retainer ring is capable of being adjusted between the bushing and the screed extension portion frame to eliminate an uncontrolled movement of the screed extension tube and the screed extension portion.
In another aspect of the disclosure, a paving machine is disclosed. The paving machine includes a tractor including a frame and a hopper mounted on the frame, the hopper configured to hold a paving material to be distributed to a paving surface. The paving machine may further include a screed assembly mounted on the frame and configured to receive the paving material from the hopper. A main screed portion of the screed assembly may include a screed frame having a main deflector and a screed side plate coupled thereto. The paving machine may further include a screed extension portion of the screed assembly having a screed extension portion frame, the screed extension portion being in a laterally exterior position with respect to the main screed portion. Additionally, a screed extension tube may be operably coupled to the screed frame and the screed extension portion frame; the screed extension tube may be configured to adjust the screed extension portion between a first screed width and a second screed width. The paving machine may further include an extension tube support mechanism for supporting the screed extension tube when the screed assembly is adjusted between the first width and the second width. The extension tube support mechanism may include a bushing circumferentially surrounding the screed extension tube and disposed within a bushing recess defined in the screed extension portion frame. Furthermore, the extension tube support mechanism may include a retainer ring that circumferentially surrounds and is in direct contact with at least a portion of the bushing, wherein the retainer ring is capable of being adjusted between the bushing and the screed extension portion frame to eliminate an uncontrolled movement of the screed extension tube and the screed extension portion.
In yet another aspect of the disclosure, an extension tube support mechanism for a screed assembly including a main screed portion and a screed assembly portion that is adjustable between a first screed width and a second screed width is disclosed. The screed extension tube support mechanism may include a screed extension tube operably coupled to a screed frame and a screed extension portion frame, the screed extension tube configured to adjust the screed extension portion between the first screed width and the second screed width. Furthermore, the extension tube support mechanism may include a bushing circumferentially surrounding the screed extension tube and disposed with a bushing recess defined in the screed extension portion frame. Additionally, the extension tube support mechanism may include a retainer ring that circumferentially surrounds and is in direct contact with at least a portion of the bushing, wherein the retainer ring is capable of being adjusted between the bushing and the screed extension portion frame to eliminate an uncontrolled movement of the screed extension tube and the screed extension portion.
An exemplary embodiment of a paving machine 20 is shown generally in
In one embodiment, the paving machine 20 further includes a hopper 34 supported by the frame 26 and the hopper 34 is configured to receive a supply of paving material (e.g., asphalt) to be distributed by the paving machine 20. Moreover, a conveyor (not shown) may be operably coupled between the hopper 34 and a screed assembly 36 attached to a rear portion of the paving machine 20. The conveyor (not shown) conveys or otherwise transports the paving material from the hopper 34 towards the screed assembly 36 and the paving material is distributed along the paving surface (i.e., roadway, driveway, sidewalk or other such surface). The screed assembly 36 then smoothens and, at least partially, compacts the paving material into a mat along the desired paving surface.
Furthermore, the screed assembly 36 includes a main frame 38, and a screed extension portion 40, located laterally exterior from the main frame 38. Additionally, in some embodiments the screed assembly 36 includes one or more screed extension tubes 42 which are extendably coupled between the main frame 38 and a screed extension frame 44. Moreover, the screed extension tube 42 and/or the screed extension portion 40 is operably coupled to one or more actuation devices (not shown), such as but not limited to a hydraulic cylinder, a linear actuator or other such actuating device. As such, activation of the one or more actuation devices (not shown) can extend and retract the screed extension portion 40 to widen and/or narrow the screed assembly 36 width, as needed.
Referring now to
The central screed portion 46 includes a substantially vertical (i.e., within manufacturing tolerances) deflector 52 and a tamper bar 54 along a bottom portion of the deflector 52. The tamper bar 54 may serve to pre-compact the paving material that is distributed from the conveyor (not shown) prior to being compacted by the central screed portion 46. As discussed above, the central screed portion 46 additionally includes the central screed side plates 50 mounted on the laterally outward-facing sides of the central screed portion 46. In an embodiment, the central screed side plates 50 are substantially perpendicular (i.e., within manufacturing tolerances) to the central screed deflector 52. Similarly, each of the screed extension portions 40 includes a deflector 56 and a tamper bar 54 extending along the bottom edge of the deflector 56. The tamper bar 54 may serve to pre-compact the paving material distributed in front of each screed extension portion 40.
Referring now to
In some embodiments, the screed extension tube 42 includes one or more bushings 58 that circumferentially surround an outer surface of the screed extension tube 42. The one or more bushings 58 help facilitate the extension and retraction of the screed extension tube 42 during the width adjustment of the screed assembly 36. Furthermore, the one or more bushings 58 may be incorporated into a screed extension tube support mechanism 60 that provides both movement and support to the screed extension tube 42 and screed extension portion 40 when the screed extension portion 40 is extended laterally away from the central screed portion 46. For example, when the screed extension portion 40 is in the first position 48 (i.e., extended position); the screed extension tube 42 and the one or more bushings 58 may provide support to control the movement of the screed extension portion 40. Additionally, when the screed extension portion 40 is extended a desired distance away from the central screed portion 46, the screed extension portion 40 may move up and down along a vertical axis V and/or forwards and backwards along a transverse axis T. Such movement along the vertical V and transverse T axes may generate an undesired or uncontrolled movement of the screed extension portion 40 during operation of the paving machine 20.
In one non-limiting example, the tapered compression ring 70 includes a tapered inner surface 72. Accordingly, an inner diameter 74 of the tapered compression ring 70 increases and/or decreases while moving along the tapered inner surface 72. Moreover, a set of threads 76 is circumferentially defined around at least a portion of an outer surface 78 of the tapered compression ring 70. An inner surface 61 of the screed extension frame 44 includes a corresponding set of threads 80 which mate with the set of threads 76 around the outer surface 78 of the tapered compression ring 70. As a result, adjusting the tapered compression ring 70 (i.e., turning clockwise or counterclockwise) will adjust a position of the tapered compression ring 70 and increase or decrease the inner diameter 74 of the tapered compression ring 70 with respect to the split solid bearing 62. In some embodiments, the tapered compression ring 70 is rotated such that the inner diameter 74 is adjusted to compress the split solid bearing 62 onto the screed extension tube 42. As a result, the tapered compression ring 70 may be adjusted (i.e., tightened or loosened) to provide the necessary support to the screed extension tube 42 and other components to help remove and/or minimize the uncontrolled movement of the screed assembly 36. Additionally, a set screw 82 may extend through the screed extension frame 44 and align with the outer surface 78 of the tapered compression ring 70. The set screw 82 may be adjusted (i.e., loosened) to allow for adjustment of the tapered compression ring 70 and the set screw may be adjusted (i.e., tightened) to directly contact the outer surface 78 of the tapered compression ring 70 once the split solid bearing 62 is properly compressed or otherwise adjusted relative to the screed extension tube 42.
The tapered retaining collar 84 includes a set of threads 98 circumferentially defined around a portion of an outer surface 100 of the tapered retaining collar 84. Furthermore, a portion of the inner surface 94 of the screed extension frame 44 includes a corresponding set of threads 102 which mate with the set of threads 98 around the outer surface 100 of the tapered retaining collar 84. As a result, adjusting the tapered retaining collar 84 (i.e., turning clockwise or counterclockwise) will tighten or loosen (i.e., increase or decrease) the contact between the tapered surface 90 of the tapered retaining collar 84 and the tapered surface 96 of the screed extension frame 44. This in turn may tighten or loosen the fit of the bushing around the screed extension frame 44. Put another way, tightening the tapered retaining collar 84 will cause the first surface 86 of the tapered retaining collar 84 to compress or otherwise tighten the fit of the bushing 58 around the screed extension tube 42 to provide the necessary support to the screed extension tube 42 and other components to remove and/or minimize any uncontrolled movement of the screed assembly 36.
In one non-limiting example, the uncontrolled movement of the screed assembly 36 discussed above, is characterized by an undesired movement of the screed extension portion 40 that occurs when the bushing 58 is loosely adjusted around the screed extension tube 42. As a result, the screed extension tube 42, as well as the screed extension portion 40, is able to move forwards, backwards, upwards or downwards, and such movement can have a negative impact on paving quality. In some cases, a minor adjustment issue (i.e., loose bushing 58) can cause a significant amount of uncontrolled movement at the lateral exterior portion of the screed extension portion 40. Accordingly, reducing or eliminating the uncontrolled movement of the screed extension portion 40 during paving will improve the uniformity and other such quality related characteristics of the finished paved material (i.e., asphalt) mat produced by the paving machine 20.
In one embodiment, the tapered retaining collar 84 includes one or more adjustment holes 104 for the adjustment (i.e., tightening and loosening) of the tapered retaining collar 84. For example, the one or more adjustment holes 104 may be compatible for use with a spanner wrench or other such adjustment device. Furthermore, the screed extension tube support mechanism 60 may include a set screw 106 that extends through the screed extension frame 44 and aligns with the outer surface 100 of the tapered retaining collar 84. The set screw 106 may be adjusted (i.e., loosened) to allow for adjustment of the tapered retaining collar 84 and the set screw 106 may be adjusted (i.e., tightened) to directly contact the outer surface 100 of the tapered retaining collar 84 once the bushing 58 is properly compressed or otherwise adjusted around the screed extension tube 42.
The present disclosure finds potential application in any paving machine 20 that utilizes one or more screed extension portions 40 to increase the available paving width. Further, the disclosure may be applicable to screed assemblies 36 with one or more extendable screed portions 40 that have a screed extension support mechanism 60. Further, the disclosure may be specifically applicable to screed extension support mechanisms 60 to help reduce or remove uncontrolled and undesired movement of the screed extension portions 40 during operation of the screed assembly 36.
The present disclosure allows for movement of the screed assembly 36 during operation in order to properly adjust the paving width and other such parameters of the screed assembly 36. The paving machine 20 performance may at least partially depend on the ability of the screed assembly 36 to be consistently and repeatedly adjusted. For example, the screed assembly 36 may include one or more screed extension tubes 42 that are coupled to the central screed portion 46 and the screed extension portion 40. The one or more screed extension tubes 42 are actuated to extend and/or retract the screed extension portion 40 such that the screed assembly 36 width is adjusted to the desired or required paving width. Furthermore, the screed extension tubes 42 may include one or more bushings 58 or bearings which help facilitate the extension and retraction of the of the screed extension portion 40. Currently, the solid bushings and/or bearings may be used with the screed extension tubes 42. Such bushings and/or bearings are typically installed using a press and interference fit, or slip fit and mechanical retention. Such installation does not allow for adjustment of the bushings and/or bearings in order to minimize or remove the uncontrolled movement of the screed assembly 36.
The present disclosure provides a screed extension tube support mechanism 60 that facilitates the consistent movement (i.e., extension and retraction) of the screed assembly 36 during extension and retraction of the screed extension portion 40. Additionally, the screed extension tube support mechanism 60 allows the bushing 58 and/or the split solid bearing 62 to be adjusted to minimize and/or reduce uncontrolled movement of the screed assembly. In other words, the screed extension support mechanism 60 allows the bushing 58 and/or the split solid bearing 62 to be adjusted (i.e., tightened or loosened) to adjust the fit of the bushing 58 and/or the split solid bearing 62 around the screed extension tube 42. Such adjustment capability allows for a reduction or elimination of uncontrolled movement of the screed assembly 36 during operation of the paving machine 20.
The screed extension tube support mechanism 60 provides a threaded interface between the screed extension frame 44, and a tapered compression ring 70 or tapered retaining collar 84. In one non-limiting example, a split solid bearing 62 circumferentially surrounds and is slidably engaged with the screed extension tube 42. The tapered compression ring 70 is inserted over an end of the screed extension tube 42 such that the tapered inner surface 72 of the tapered compression ring 70 engages with at least a portion of the split solid bearing 62. Furthermore, in an embodiment, the tapered inner surface 72 may be configured such that as the tapered compression ring 70 is tightened, the inner diameter 74 of the tapered compression ring 70 decreases and the tapered inner surface 72 interacts with the split solid bearing 62 to compress the bearing onto the surface of the screed extension tube 42. Conversely, when the tapered compression ring 70 is loosened, the inner diameter 74 of the tapered adjustment ring increases and the tapered inner surface 72 interacts with the split solid bearing 62 to decompress the bearing from the surface of the screed extension tube 42.
Additionally, the screed extension tube support mechanism 60 may provide the threaded interface between the screed extension frame 44 and a tapered retaining collar 84. Accordingly, the bushing 58 may circumferentially surround and be slidably engaged with the screed extension tube. The tapered retaining collar 84 is inserted over an end of the screed extension tube and adjacently positioned to the outer surface of the bushing 58. The tapered retaining collar 84 has a first surface 86 that corresponds to the outer surface of the bushing 58 and a second surface 88 that defines a tapered surface 90 of the tapered retaining collar 84. Furthermore, the inner surface 94 of the screed extension frame 44 includes a tapered surface 96 which corresponds and is complimentary with the tapered surface 90 of the tapered retaining collar 84. Thus, when the tapered retaining collar 84 is threaded or otherwise tightened into the screed extension frame 44, the tapered surface 90 of the tapered retaining collar 84 interacts with the tapered surface 96 of the screed extension frame 44 to compress or otherwise tighten the fit the bushing 58 around the screed extension tube 42. Conversely, when the tapered retaining collar 84 is unthreaded or otherwise loosened from the screed extension frame 44, the tapered surface 90 of the tapered retaining collar 84 interacts with the tapered surface 96 of the screed extension frame 44 to decompress or loosen the fit of the bushing 58 around the screed extension tube 42.
Moreover, although the disclosure discusses the use of the tapered compression ring 70 to adjust the fit of the split solid bearing 62 and the tapered retaining collar 84 to adjust the fit of the bushing 58, it will be understood that the components of the screed extension tube support mechanism 60 are not limited as such. Thus, the tapered compression ring 70 may be used to adjust the fit of the bushing 58 and the tapered retaining collar 84 may be used to adjust the fit of the split solid bearing 62
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and assemblies without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
