WO2015179078A1

WO2015179078A1 - Screed vibration system

Info

Publication number: WO2015179078A1
Application number: PCT/US2015/027984
Authority: WO
Inventors: John Eron Jorgensen; Stephen Kreis PHELPS; Krishnakumar Dharapuram RAMAMOORTHY; Jason W. Kopacz; Luke E. Graham; Toby Andrew Frelich
Original assignee: Caterpillar Inc.
Priority date: 2014-05-20
Filing date: 2015-04-28
Publication date: 2015-11-26
Also published as: US20150337504A1

Abstract

A vibration system for a paving machine having a power source and an integrated generator is provided. The vibration system may include a power converter in electrical communication with the integrated generator, a motor drive in electrical communication with the power converter, an electric motor in electrical communication with the motor drive, and a vibratory mechanism operatively coupled to the electric motor and configured to engage at least one of a screed assembly and a tamper assembly.

Description

Description SCREED VIBRATION SYSTEM

Technical Field

The present disclosure relates generally to paving machines, and more particularly, to systems and machines for providing and supplying power to tamper and screed vibratory mechanisms of a screed.

Background

Paving machines are typically used for building roadways, parking lots, and the like, and function to deposit paving material, such as asphalt, on a paving surface to create a flat, consistent surface over which vehicles may travel. A paving machine at a construction site, such as an asphalt paver, is generally a state-of-the art self-propelled construction machine designed to receive, convey, distribute, profile and partially compact the asphalt material. The paving machine accepts heated asphalt material into a receiving hopper at the front of the machine, which is conveyed to the rear of the machine with parallel slat conveyors or other types of conveyors positioned at the bottom of the hopper. The asphalt material conveyed from the hopper is distributed along the width of an intended ribbon or mat by means of two spreading conveyors or opposing augers. The paving machine may further employ a screed with vibratory and/or tamper mechanisms to profile and compact the asphalt material into a mat on the paving surface.

The operation of the paving machine and its components may be manually controlled by an operator to dispense the asphalt material and create the mat on the paving surface. In many paving machines, systems are provided to automate and control the paving process for consistent operation of the paving machine for laying a uniform mat on the paving surface without defects compromising the integrity and longevity of the mat. The automation systems may include control over the speed of the paving machine, operation of the conveyors and augers to distribute the asphalt material, vertical positioning and temperature control of the screed, control of the screed or tamper vibrations, and the like. The control settings may be established during an initial setup process for a paving job, such as the paving of a stretch of a highway or the paving of a parking lot.

During the paving process, a tamper mechanism disposed between the augers and the screed plate may use a tamper bar, or the like, which moves up and down to strike and pre-compact the asphalt material before the asphalt material reaches the screed plate. Similarly, the screed plate may vibrate in a manner to further compact the asphalt material. Each of the tamper mechanism and the screed plate may be vibrated via an associated vibratory mechanism having any of a variety of designs familiar to those of skill in the art. Further, the vibratory mechanisms may be driven by hydraulic pumps or motors which are indirectly operated by the power source of the paving machine. In typical paving machines, for instance, a power source, such as a gas or diesel internal combustion engine, has an output shaft which drives a pump drive. The pump drive, in turn, drives multiple pumps and/or motors providing pneumatic, hydraulic and mechanical power to the various systems of the paving machine, including the vibratory mechanisms associated with the tamper mechanism, the screed, and the like.

This string of interconnected components as described results in parasitic losses and reduced efficiency that increase the overall cost of operating the paving machine. Actual implementation of such systems also tends to occupy more space on the paving machine, tractor and screed assembly. Some paving machine arrangements provide a more direct connection between a power source and a generator. For example, U.S. Pat. Appl. Publ. No. 2010/0296866, published on Nov. 25, 2010 and entitled, "Paver and Method," discloses a generator that is mounted either at the power take-off gear for the pumps of the road paver, at a suspension in the chassis of the road paver, or at a console of the combustion engine of the road paver. The generator may be driven by a permanent drive connection, such as a belt drive or a drive shaft. However, the publication does not teach any alternate connection to vibratory mechanisms associated with tamper or screed assemblies of the road paver.

In view of the inefficiencies and disadvantages present in providing vibratory screed systems in conventional paving machines, a need exists for improved integration of tamper and screed vibratory mechanisms into a paving machine and more efficient means of power delivery thereto. Summary of the Disclosure

In one aspect of the present disclosure, a vibration system for a paving machine having a power source and an integrated generator is provided. The vibration system may include a power converter in electrical communication with the integrated generator, a motor drive in electrical communication with the power converter, an electric motor in electrical communication with the motor drive, and a vibratory mechanism operatively coupled to the electric motor and configured to engage at least one of a screed assembly and a tamper assembly.

In another aspect of the present disclosure, a screed for a tractor having a power source, an integrated generator, and a power converter is provided. The screed may include a screed assembly, a tamper assembly, a vibratory mechanism operatively coupled to at least one of the screed assembly and the tamper assembly, and an electric motor operatively coupled to the vibratory mechanism. Further, the electric motor may be configured to receive an electrical signal from the power converter and mechanically drive the vibratory mechanism in response to the electrical signal.

In yet another aspect of the present disclosure, a paving machine is provided. The paving machine may include a screed assembly, a tamper assembly, an engine, an integrated generator, one or more power converters, one or more motor drives, one or more electric motors, and one or more vibratory mechanisms configured to engage at least one of the screed assembly and the tamper assembly.

Brief Description of the Drawings

Fig. 1 is a perspective view of a paving machine;

Fig. 2 is a side view of the paving machine of Fig. 1; and

Fig. 3 is a schematic view of electrical power distribution components arranged in accordance with the present disclosure implemented in the paving machine of Fig. 1.

Detailed Description

Although the following text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of protection is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible

embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the scope of protection.

It should also be understood that, unless a term is expressly defined herein, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to herein in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning.

Fig. 1 is an illustration of a paving machine 100. Although the paving machine 100 is depicted in the drawings as an asphalt paver, the presently disclosed systems may be used on any kind of paving machine for any kind of paving material that may form a layer of material on a paving surface 102 and where power is supplied to vibratory mechanisms related to such systems. The paving machine 100 includes a tractor 104 having a power source 106, such as a gas turbine engine, a gas or diesel internal combustion engine, a motor, or the like, one or more traction devices 108, and a hopper 110 for containing paving material. The traction devices 108 may be operatively coupled to the power source 106 by a transmission mechanism (not shown) to drive the traction devices 108 and propel the paving machine 100. Although the traction devices 108 are shown in the drawings as tracks, the traction devices 108 could alternatively be wheels or any other type of traction devices. The traction devices 108 could also be combinations of different types of traction devices. For example, paving machine 100 could include both tracks and wheels.

The paving machine 100 also includes an operator station 34 for one or more operators. The operator station 112 includes a seat 114 and an operation console 116 that may be mounted on a pedestal 118. The operator station 112 includes a tractor controller or electronic control module (ECM) 120 as well as a human-machine interface 122 for accepting user input and displaying information to the operator. The human-machine interface 122 may have a combination of buttons, switches, dials, levers, touch screens and other control devices that may allow the operator to input commands to the tractor ECM 120 for controlling the operation of the various components of the paving machine 100. The paving machine 100 also includes a screed 124 attached to the tractor 104 by tow arms 126 and towed behind the tractor 104 to spread and compact the paving material into a mat 128 on the paving surface 102. More specifically, the tractor 104 may include one or more augers 130 for spreading the paving material to the lateral extents of the screed 124, as well as a tamper assembly 132 and a screed assembly 134 for pre-compacting, compacting and more finely smoothing the paving material onto the paving surface 102.

On the tractor 104, the hopper 110 of the paving machine 100 contains the paving material that is to be formed into the mat 128 on the paving surface 102. The paving material may be dumped into the hopper 110 at the front of the paving machine 100 from trucks that deliver the paving material to a work site. Referring to Fig. 2, the paving machine 100 may include one or more conveyors 136 at the bottom of the hopper 110. The conveyors 136 may be positioned side-by-side and run parallel to one another proximate the center of the hopper 110 along a midline of the paving machine 100. The hopper 110 is generally configured to feed the paving material from the sides of the hopper 110 toward the center. The conveyors 136 may transport paving material from the hopper 110 to the rear of the tractor 104, where it may be dropped behind the tractor 104, in front of the screed 124 and onto the paving surface 102 in a pile 138 (shown in a cut away portion 140 of Fig. 2). As the paving machine 100 travels forward, the pile 138 may be evenly spread and compacted by the augers 130, the tamper assembly 132 and the screed assembly 134. At times, some paving material may not feed onto the conveyors 136 and rather accumulate at the outer sides of the hopper 110. In such cases, the accumulated material may be funneled onto the conveyors 136 by articulating the hopper 110 using actuators (not shown), for example, in the motion indicated by the arrows in Fig. 1. During use, the paving machine 100 employs the augers 130, the tamper assembly 132 and the screed assembly 134 to spread the pile 138, pre- compact and compact the paving material into the mat 128 on the paving surface 102. Specifically, the tamper assembly 132 is positioned in the aft of the augers 130 and configured to pre-compact the paving material exiting the augers 130. For example, the tamper assembly 132 may employ one or more tamper bars 142, such as arranged in a single or a dual tamper configuration, or any other device or mechanism ordinarily used in the art, which is caused to vibrate or otherwise controlled to repeatedly strike down on the paving material, by an associated vibratory mechanism 144. The screed assembly 134 is positioned in the aft of the tamper assembly 132 and includes one or more screed plates, or the like, configured to smooth the paving material exiting the tamper assembly 132.

Moreover, the screed plates are caused to move or vibrate by an associated vibratory mechanism 148 in a manner which enables further compaction of the paving material onto the paving surface 102. Each of the vibratory mechanisms 144, 148 can be implemented using any one or more of a variety of designs familiar to those of skill in the art. Furthermore, each of the vibratory

mechanisms 144, 148 may be operated independently or in conjunction with one another. Although not shown, the screed assembly 134 can also include any one or more of a main screed frame, screed extenders, accessory extensions, such as bolt-on extensions, or the like, each of which can be operatively coupled with the vibratory mechanism 148.

The tamper and screed assemblies 132, 134 of the screed 124, or at least the vibratory mechanisms 144, 148 associated therewith, can be powered by different power distribution arrangements. Fig. 3 illustrates one arrangement in accordance with the present disclosure of electrical power distribution components of the paving machine 100 for driving at least the screed vibration system 150, or the vibratory mechanisms 144, 148 of the screed 124. More generally, the arrangement shown in Fig. 3 serves to convert mechanical power that is output by the power source 106 into adequate electrical power that is converted back into mechanical power suited to drive the vibratory mechanisms 144, 148 of the tamper and screed assemblies 132, 134. More particularly, a rotating output shaft 152 of the power source 106 is connected to a pump drive 154 within the tractor 104. The pump drive 154 houses internal gear drives (not shown) that in turn have pumps and motors (not shown) coupled thereto. As the output shaft 152 of the power source 106 drives the gear drives of the pump drive 154, the pumps and motors generate hydraulic, pneumatic and mechanical power for various other components and systems of the paving machine 100.

Still referring to Fig. 3, the pump drive 154 further includes an integrated generator (IG) 156 integrated into or assembled with the pump drive 154. The integrated generator 156 has an input shaft (not shown) that is operatively coupled to the output shaft 152 of the power source 106, instead of being indirectly coupled to the output shaft 152 through other pumps or motors that may be driven by the pump drive 154. The input shaft of the integrated generator 156 may be coupled directly to the output shaft 152 via any one or more of belts, intermediate drive shafts, or gear drives associated with the pump drive 154, or the like. Particular connection arrangements for converting rotation of the output shaft 152 of the power source 106 into rotation of the input shaft of the integrated generator 156 within the pump drive 154 will be apparent to those skilled in the art and are contemplated by the inventors as having use in paving machines 100 in accordance with the present disclosure. In the present embodiment, the integrated generator 156 may be a switched reluctance generator that may be, for example, of the type disclosed in Susitra, et al, Switched Reluctance Generator - Modeling, Design, Simulation, Analysis and Control - A Comprehensive Review, Int'l J. Computer Appls., Vol. 1, No. 2, pp. 10-16 (2010) and Hrabovcova et al, Output Power of Switched Reluctance Generator with regard to the Phase Number and Number of Stator and Rotor Poles, Elec. & Elec. Eng'g, No. 3, pp. 25-30 (2011), which are expressly incorporated by reference herein. A switched reluctance generator such as those described in the references can provide more power in a smaller package relative to the currently used generators, thereby facilitating integration of the generator 156 with the pump drive 154.

In response to mechanical input, and more particularly rotational input, received from the power source 106, the input shaft and thus a rotor (not shown) within the integrated generator 156 may be caused to rotate relative to a corresponding stator (not shown). Electromagnetic interaction between the poles of the rotor and the stator may generate electrical signals, for instance, alternating current (AC) in one or more phases, to be communicated to an input of one or more power converters 158. In turn, the power converters 158 convert, process, condition, regulate, or otherwise generate appropriate electrical output signals to be sourced to one or more of the vibratory mechanisms 144, 148 associated with the tamper and screed assemblies 132, 134. Specifically, as shown in Fig. 3, each vibratory mechanism 144, 148 is driven by an associated electric motor 160, 162, and each electric motor 160, 162 is powered by an associated motor drive 164, 166. For example, each motor drive 164, 166 receives a DC signal received from the power converters 158, and converts the DC signal into an AC signal appropriate for driving the associated electric motor 160, 162. The AC signal in turn generates an electromagnetic field within the stator (not shown) of the electric motor 160, 162 which causes the corresponding rotor (not shown) to rotate and mechanically drive the vibratory mechanism 144, 148 attached thereto.

In the screed vibration system 150 provided, the electric motor 160 operatively coupled to the tamper vibratory mechanism 144 is an AC induction motor, such as a three-phase induction motor, and the electric motor 162 operatively coupled to the screed vibratory mechanism 148 is an AC induction motor, such as a single-phase induction motor. The motor drive 164 for the tamper vibratory mechanism 144 is an AC motor drive configured to convert the DC signal supplied by the power converters 158 into appropriate AC signals for operating the three-phase AC induction motor 160, and the motor drive 166 for the screed vibratory mechanism 148 is an AC motor drive configured to convert the DC signal supplied by the power converters 158 into appropriate AC signals for operating the single-phase AC induction motor 162. While only one arrangement is depicted in the drawings, other arrangements for operating the vibratory mechanisms 144, 148 of the tamper and screed assemblies 132, 134 will be readily apparent to persons of ordinary skill in the art. In other modifications, for example, each of the vibratory mechanism 144, 148 may be driven by other types of electric or AC induction motors having more or less phases than described herein. In other alternatives, the vibratory mechanisms 144, 148 may be operated by a single electric motor that is further driven by a single motor drive. In further alternatives, a single motor drive may be used to drive both of the electric motors 160, 162. In still further alternative embodiments, the power converters 158 may be configured to supply AC signals directly to the electric motors 160, 162 sufficient to bypass the need for the motor drives 164, 166.

In response to electrical input received from the integrated generator 156, the power converters 158 are also capable of supplying or outputting different electrical signals to operate other components of the tractor 104 and the screed 124 as shown in Fig. 3. For example, the power converters 158 may supply one or more DC signals to operate heating elements 168 associated with the screed 124 and the screed assembly 134. The power converters 158 in Fig. 3 are also configured to supply a DC signal to one or more of the conveyors 136 of the tractor 104 via a motor drive 170, or the like. The power converters 158 are also capable of charging or storing electrical energy within an energy storage device 172, such as a battery of the tractor 104.

Specifically, the power converters 158 supply an AC signal to a charging circuit 174, which may employ transformers, rectifiers, regulators, and the like, adapted to convert the AC signal into a suitable DC signal for charging the energy storage device 172. Still further, the power converters 158 may supply AC or DC signals to any number of other auxiliary devices 176 associated with the paving machine 100.

In the particular embodiment of Fig. 3, for example, the power converters 158 supply AC signals to a transformer 178, which may in turn supply correspondingly adjusted AC signals to one or more actuators 180, ventilation and cooling systems 182, auxiliary power outlets 184, and the like. The actuators 180 may include any one or more of crowning actuators, slope actuators, height actuators, endgate actuators, or any other actuators commonly used in association with paving applications. Crowning actuators may be used to adjust a crown angle or a general curvature of the screed 124. Additionally, slope actuators may be used to adjust a slope of the screed 124, for example, by adjusting a position or slope of the extenders that are attached to the screed 124, or any other suitable form of screed support. Similarly, height actuators may be used to adjust the height of the extenders attached to the screed 124. Endgate actuators may be provided on paving machines 100 with optional endgates (not shown) disposed at the ends of the screed 124. The ventilation and cooling systems 182 may provide pumps, fans, or the like, which may be driven by the AC signal supplied by the power converters 158 and/or the transformer 178. Furthermore, the auxiliary power outlets 184 may provide one or more electrical outlet panels disposed on the paving machine 100.

Industrial Applicability

In general, the foregoing disclosure finds utility in paving applications involving use of a screed or screed assembly associated with a tractor. The present disclosure, however, may also find utility in various other industrial applications in which vibratory mechanisms, or other machine tools or components, derive power from the mechanical output of a primary power source, such as an internal combustion engine, or the like. More specifically, the disclosed systems may be used to provide power distribution arrangements which are capable of replacing conventional hydraulic pump arrangements and provide a more direct connection between the power source and the associated vibratory mechanisms, machine tools or components.

The present disclosure provides an integrated generator which feeds power to one or more power converters, which in turn, sources electric power to electric motors that operate tamper and/or screed vibratory mechanisms of a screed. In particular, a switched reluctance generator, or the like, is directly integrated into the pump drive and coupled to the mechanical output of the power source or engine. Further, AC induction motors replace hydraulic pump arrangements conventionally used to drive vibratory mechanisms of tamper and screed assemblies. By providing more of a direct connection to the power source, and by eliminating the need for networks of interconnected hydraulic pumps, the present disclosure reduces parasitic losses and improves efficiency. Additionally, by simplifying the power transfer between the power source and the tamper and screed assemblies, the present disclosure reduces the overall weight of the machine, space requirements as well as the costs of

implementation and operation.

From the foregoing, it will be appreciated that while only certain embodiments have been set forth for the purposes of illustration, alternatives and modifications will be apparent from the above description to those skilled in the art. These and other alternatives are considered equivalents and within the spirit and scope of this disclosure and the appended claims.

Claims

1. A vibration system ( 150) for a paving machine (100) having a power source (106) and an integrated generator (156), the vibration system (150) comprising:

a power converter (158) in electrical communication with the integrated generator (156);

a motor drive (164, 166) in electrical communication with the power converter (158);

an electric motor (160, 162) in electrical communication with the motor drive (164, 166); and

a vibratory mechanism (144, 148) operatively coupled to the electric motor (160, 162) and configured to engage at least one of a screed assembly (134) and a tamper assembly (132).

2. The vibration system (150) of claim 1, wherein the power converter (158) is configured to electrically communicate with a switched reluctance generator (156) that is integrated with an engine (106) of the paving machine (100).

3. The vibration system (150) of claim 1, wherein the motor drive (164, 166) is an AC motor drive (164, 166) configured to receive DC signals from the power converter (158) and output AC signals to operate the electric motor (160, 162).

4. The vibration system (150) of claim 1, wherein the electric motor (160, 162) is an AC induction motor (160, 162) configured to receive AC signals from the motor drive (164, 166) and provide rotational output for operating the vibratory mechanism (144, 148).

5. The vibration system (150) of claim 1, wherein the vibratory mechanism (144, 148) includes at least a first vibratory mechanism (148) for engaging the screed assembly (134) and a second vibratory mechanism (144) for engaging the tamper assembly (132), the first and second vibratory mechanisms (144, 148) being operated independently by respective first and second electric motors (160, 162) and first and second motor drives (164, 166).

6. A screed (124) for a tractor (104) having a power source (106), an integrated generator (156), and a power converter (158), the screed

(124) comprising:

a screed assembly (134);

a tamper assembly (132);

a vibratory mechanism (144, 148) operatively coupled to at least one of the screed assembly (134) and the tamper assembly (132); and

an electric motor (160, 162) operatively coupled to the vibratory mechanism (144, 148), the electric motor (160, 162) being configured to receive an electrical signal from the power converter (158) and mechanically drive the vibratory mechanism (144, 148) in response to the electrical signal.

7. The screed (124) of claim 6, wherein the vibratory mechanism (144, 148) is configured to engage each of the screed assembly (134) and the tamper assembly (132) independently.

8. The screed (124) of claim 6, wherein the electric motor

(160, 162) is an AC induction motor (160, 162) that is driven by a motor drive (164, 166), the motor drive (164, 166) being electrically coupled to the power converter (158), the motor drive (164, 166) being configured to receive DC signals from the power converter (158) and supply AC signals to the AC induction motor (160, 162).

9. The screed (124) of claim 6, wherein the vibratory mechanism (144, 148) includes at least a first vibratory mechanism (148) for engaging the screed assembly (134) and a second vibratory mechanism (144) for engaging the tamper assembly (132), the first and second vibratory mechanisms (144, 148) being operated independently by respective first and second electric motors (160, 162), the first electric motor (162) being a single-phase AC induction motor (162) and the second electric motor (160) being a three-phase AC induction motor (160).

10. The screed (124) of claim 6, further comprising a plurality of actuators (180) configured to adjust one or more of a screed crown angle, a screed slope, and a screed height, the actuators (180) being powered by the power converter (158).