The present disclosure relates generally to a paving machine, and more particularly to a screed assembly of the paving machine having a temperature sensor to monitor temperature of paving material.
When building roadways, parking lots and the like, paving machines are used to deposit paving material, such as asphalt, on a paving surface to create a flat, consistent surface over which vehicles may travel. The paving machine typically works with a compactor to create a finished mat surface. The paving machine is generally a self-propelled machine designed to receive, convey, distribute, and partly compact the paving material. Typically, the paving machine receives heated paving material in a hopper positioned at a front of the paving machine, conveys the paving material from the hopper to a rear of the paving machine with conveyors, distributes the paving material along a desired width with an auger, and forms the paving material into a mat with a screed assembly. The mat is further compacted by one or more compactors.
One or more compactors generally follow behind a paver and compact the mat to a desired degree or extent. The compactor may include a drum assembly having a vibratory mechanism. Both amplitude and frequency of vibration may be controlled to establish degree of compaction.
The extent of compaction effort mainly depends on the temperature of the paving material. For example, if sections of the mat are at a lower than preferred temperature, the one or more compactors may have to make additional passes across these sections to ensure sufficient compaction. On the other hand, if sections of the formed mat are at a higher than preferred temperature, compactor operators will have to take caution to avoid over compacting these sections. Therefore, for laying a good finished mat, temperature of the paving material is significant for proper compaction by the screed assembly and thereafter by one or more compactors that follow the paving machine.
Current systems include temperature scanning devices and infrared cameras mounted to the screed assembly to scan and determine the surface temperature of the mat surface formed by the screed assembly. These systems measure the surface temperature of the mat surface laid down by the screed assembly. The surface temperature of the mat surface may be different from the core temperature of the paving material. Further, these systems may be expensive.
US Patent Application Publication No. 20150003914 discloses a temperature sensor configured to determine the temperature of the screed plate. The screed plate has a top surface, a thickness, and an opening in the top surface. The opening extends into the thickness of the screed plate and receives at least a portion of the temperature sensor. The temperature sensor monitors the temperature of the screed plate and based on the temperature of the screed plate a controller adjusts the heating of the screed plate.
However, measuring the temperature of a screed plate may not provide an accurate measurement of the temperature of the paving material that is needed to control the compaction process.
In an aspect of the present disclosure, a screed assembly for a paving machine is disclosed. The screed assembly includes a screed plate having a front edge, a first plate having a first thickness. The first plate is positioned in front of the front edge of the screed plate. At least one temperature sensor is coupled to the first plate. The temperature sensor is configured to determine a temperature of a paving material, whereby the temperature of the paving material is measured before the paving material comes into contact with the screed plate.
In another aspect of the present disclosure, a paving system is disclosed. The paving system includes a paving machine, a compactor and a controller. The compactor is configured to apply a variable compaction effort to a paving material. The paving machine includes a screed plate having a front edge, a first plate is positioned in front of the front edge of the screed plate. The first plate has a first thickness and a temperature sensor is coupled to the first plate and positioned at least partly within the first thickness and configured to determine a temperature of the paving material, whereby the temperature of the paving material is measured before the paving material comes into contact with the screed plate. The controller is configured receive a temperature data from the temperature sensor and control the variable compaction effort of the compactor based on the temperature data.
In yet another aspect of present disclosure, a method for paving a ground surface is disclosed. The method includes providing a paving machine having a first plate in front of a front edge of a screed plate. The first plate has a temperature sensor configured to provide temperature of a paving material, whereby the temperature of the paving material is measured before the paving material comes into contact with the screed plate, providing a compactor applying a variable compaction effort to the paving material, providing the temperature of the paving material to the compactor and adjusting the variable compaction effort of the compactor based on the temperature of the paving material.
Reference will now be made in detail to the embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference number will be used throughout the drawings to refer to the same or like parts.
An exemplary embodiment of a paving system 100 is shown in
The hopper 118 is positioned at the front of the paving machine 102 and contains the paving material that is to be formed into a mat on the ground. The paving material may be dumped into the hopper 118 from trucks that deliver the paving material to a work site. The paving machine 102 may also include one or more conveyors (not shown) at the bottom of the hopper 118. The conveyors transport the paving material from the hopper 118 to the rear of the tractor 106. The paving machine 102 may further include one or more augers or other material feed components instead of or in addition to the conveyors. The augers distribute the paving material in front of a screed assembly 120. As the paving machine 102 travels forward, the paving material is evenly spread and compacted by the screed assembly 120.
The screed assembly 120 is positioned at the rear end of the tractor 106. The screed assembly 120 is attached to the tractor 106 by tow arms 178 and towed behind the tractor 106 to spread and compact the paving material into the mat on the ground surface. Referring to
Referring to
In the embodiment illustrated, the temperature sensor 128 is positioned at least partly into the first thickness ‘d’ of the first plate 126. In an alternate embodiment, the temperature sensor 128 may be positioned completely into the first thickness ‘d’ of the first plate 126. The temperature sensor 128 is configured to measure the temperature of the paving material before the paving material comes into contact with the screed plate 124. Referring to
When engaged with the first plate 126, the outer surface profile 138 of the temperature sensor 128 may be substantially flush with the surface profile 134 of the first plate 126 and forms a continuous surface profile i.e. the first plate 126 and the temperature sensor 128 are simultaneously in contact with the paving material. In an aspect of the present disclosure, plurality of temperature sensors 128 may be coupled to the first plate 126 and positioned at least partly within the first thickness ‘d’. The plurality of temperature sensors 128 may be positioned at predefined locations on the first plate 126. The plurality of temperature sensors 128 are positioned to determine the temperature of the paving material along the complete width of the mat.
The temperature sensor 128 may be a “contact” type of temperature sensor, such as, for example, a thermocouple with a sensing junction, a thermostat, resistive temperature detectors (RTD) or any other temperature sensing device known in art. In an embodiment, the temperature sensor 128 may be made of a high heat conductive material such as aluminum or any other material with high heat conductivity. The high heat conductive material is configured to contact and determine the temperature of the paving material when it reaches the screed assembly 120.
In an alternate embodiment, as illustrated in
In another embodiment, illustrated in
The temperature sensor 128 may be mounted to the first plate 126, the second plate 140 or the third plate 146 using methods known in the art including welding, press fitting or by threaded engagement. Referring to the embodiments illustrated in
In an alternate embodiment, a high heat conductive insert may be coupled with the temperature sensor 128 disposed on the first plate 126, the second plate 140 and/or the third plate 146. For example, the high heat conductive insert is positioned within the opening 136 extending into the first thickness ‘d’ of the first plate 126. The temperature sensor 128 is coupled to the high heat conductive insert. The high heat conductive insert prevents the wearing of the temperature sensor 128.
In yet another embodiment, the screed plate 124 may further include multiple screed plate openings towards the front of the screed plate 124. The temperature sensor 128 with a thermal insulator may be positioned in the screed plate openings. The thermal insulator is configured to limit the heat transfer from the screed plate 124 to the temperature sensor 128.
In an embodiment, the surface profile 134 of the first plate 126, the second surface profile 142 of the second plate 140 and the third surface profile 150 of the third plate 146 may be different. In an alternate embodiment, the surface profile 134 of the first plate 126, the second surface profile 142 of the second plate 140 and the third surface profile 150 of the third plate 146 may be identical to each other. Further, the first plate 126, the second plate 140 and the third plate 146 may have same thickness i.e. the thickness ‘d’, thickness ‘t’ and thickness ‘h’ are same. In another embodiment, the first plate 126, the second plate 140 and the third plate 146 may have different thickness i.e. the thickness ‘d’, thickness T and thickness ‘h’ are different.
As shown in
Referring to
The memory unit 158 may include one or more storage devices configured to store information used by the controller 154 to perform certain functions related to the present disclosure. The processing unit 160 may include one or more known processing devices, such as a microprocessor or any other device known in the art. In the embodiment illustrated, the memory unit 158 and processing unit 160 may be included together in a single unit. In an alternate embodiment, the memory unit 158 and the processing unit 160 may be incorporated separately.
The controller 154 may store a standard temperature data for the paving material. In the embodiment illustrated, the standard temperature data refers to the temperature of the paving material at which a proper finished mat is created on the ground surface. In an alternate embodiment, the memory unit 158 may also store an algorithm to compare the temperature data received from the temperature sensor 128 with the standard temperature requirement.
The controller 154 receives the temperature of the paving material from the temperature sensor 128. The controller 154 is configured to control temperature of the screed plate 124 according to the temperature data received from the temperature sensor 128, for example, if the temperature of the paving material is lower than the standard temperature, then the controller 154 may transmit signal to increase the temperature of heating elements present in the screed plate 124. The controller 154 further receives the positional data of the temperature sensors 128 from the position detectors 152. The sensed position data output from the position detector 152 and the temperature data from the temperature sensor 128 may be recorded onto high capacity discs or cards (not shown) for maintaining a historical record of the thermal profile of the mat surface as laid.
The processing unit 160 utilizes information from the position detector 152 and the temperature sensor 128 to formulate a heat map of the ground surface. The heat map indicates the temperature of the paving material at various locations on the ground surface. Further, the controller 154 may transmit the temperature data, the positional data or the heat map to the compactor 104.
The compactor 104 is configured to compact soil, gravel, concrete, or asphalt in the construction of roads and foundations. As illustrated in
In an illustration of the present embodiment, the compactor 104 may include a receiver 172. The receiver 172 is configured to receive compactor control commands from the controller 154 based on the temperature data. In an embodiment, the controller 154 may control the variable compaction efforts of the compactor 104 based on the positional data associated with the temperature data. Therefore, the compaction effort of the compactor 104 may be varied based on the different temperatures of the paving material associated with different locations. This helps in ensuring proper compaction of the paving material along the entire mat. The receiver 172 further generates control commands for the front vibratory apparatus 166 and the back vibratory apparatus 170 to vary the compaction efforts i.e. changing energy transfer between compactor 104 and the mat. The front vibratory apparatus 166 and the back vibratory apparatus 170 may have an adjustable vibration amplitude, adjustable vibration frequency and/or adjustable vibration direction. Varying energy transfer could also include turning one or both of front vibratory apparatus 166 and back vibratory apparatus 170 on or off. In an embodiment, the heat map is transmitted to the display unit 156 disposed in the compactor 104.
The controller 154 may be communicably coupled to the display unit 156. In an embodiment, the display unit 156 may be remotely connected with the controller 154. In an alternate embodiment, the display unit 156 may be in communication with the controller 154 using a wire. In another embodiment, the display unit 156 may be any portable device which may be operated by a personnel present outside the paving system 100. The display unit 156 may be configured to display the temperature data from the controller 154. The display unit 156 may also be configured to display the heat map generated by the controller 154. The display unit 156 may be included in the paving machine 102. In an alternate embodiment, the display unit 156 may be positioned in the central station for remotely controlled machines. In an embodiment, the operator may also manually adjust the compaction efforts of the compactor 104 according to the heat map.
In operation, the paving machine 102 receives the paving material in the hopper 118, positioned in front of the paving machine 102. The augers conveys the paving material from the hopper 118 to the rear of the machine with conveyors and distributes the paving material along a desired width. The screed assembly 120 includes the temperature sensor 128, positioned partly within the thickness of the first plate 126 to measure the temperature of the paving material before it comes in contact with the screed plate 124. The first plate 126 pre-compacts the paving material and guides the paving material to the screed plate 124. During paving operations, it is important to receive accurate readings of the temperature of the paving material when it first comes in contact with the screed plate 124. Further, it is also useful to determine the temperature of the paving material prior to the compaction process by the compactor 104. The compactor 104 applies variable compaction effort on the mat of paving material formed by the screed plate 124 based on the temperature of the paving material. The determined temperature of the paving material is transmitted to the controller 154. The controller 154 may control the temperature of the heating elements present in the screed plate 124 according to the temperature of the paving material. The heating of the screed plate 124 helps in better shaping and spreading of the paving material during paving process by the paving machine 102, when the temperature of the paving material is less than a desired temperature. The controller 154 further generates the heat map of the mat and transmit the heat map to the compactor 104. The controller 154 controls the variable compaction effort of the compactor 104 according to the heat map and the temperature data. The compaction effort may be varied by varying amplitude and frequency of the vibration of the front vibratory apparatus 166 and/or the back vibratory apparatus 170. Additionally, the controller 154 may also give instructions to one or more compactors 104 to make additional passes to for desirable compaction of the paving material.
Compaction effort necessary to obtain desired degree of compaction depends on the temperature of the paving material. As the temperature sensor 128 provides correct temperature of the paving material, the variable compaction effort of the compactor 104 is controlled. This helps in preventing over compaction or less than optimal compaction of the paving material and thereby ensuring good quality of mat surface. Thus, determination of accurate temperature value of the paving material improves the compaction process and results in the proper finished mat surface.
Further, as the plurality of temperature sensors 128 are provided, the controller 154 continue to receive the temperature data of the paving material when one or more of the plurality of temperature sensors 128 fail. Thereby, ensuring smooth functioning of the paving system 100 and proper compaction of the mat surface.
While aspects of the present disclosure have seen 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 methods without departing from the spirit and 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.
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