Pump for melted thermoplastic materials

Abstract

An improvement to surface marking devices for pumping and circulating melted thermoplastic material to various surfaces including roads, parking lots and the like is provided. The pump for melted thermoplastic is comprised of a cold section and a hot section. The hot section is connected to a fluid or electric motor, or alternatively, an internal combustion engine for providing rotation to the pump. The connection to provide rotation to the hot section is through the cold section, which is spaced away from the hot section and connected with shafting to provide rotation to the hot section. A heating jacket is secured to the hot section for transferring heat from an external source to the hot section. The spacing between the hot and cold sections provides the ability to rebuild the hot section of the pump without removal from the cold section and without removal from the vehicle to which it is attached.

Claims

1. A pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface comprising: a cold section (12) including a top portion (30) and a bottom portion (36) secured together, the cold section having an input (82) to through shafts (22, 24), said through shafts (22, 24) intermeshed, in a space between said top portion (30) and said bottom portion (36) of said cold section, to rotate in opposite directions and having an extended length extending out of a bottom portion of said cold section (12) to a hot section (14); said hot section (14) including a top surface and an inlet port (46) for drawing in melted thermoplastic material and outlet port (48) for providing pressurized melted thermoplastic material therefrom, said hot section including transfer lobes (62, 64) operably connected to the second ends (58, 60) of said through shafts (22, 24) and oriented on said through shafts to intermesh with each other for transfer of said molten thermoplastic around an inside perimeter (84) of said hot section (14) between the inlet port (46) and the outlet port (48); a heating jacket (18) covering a portion of said hot section (14) for heating said hot section (14); at least one separating pillar (16) extending between a bottom surface (42) of said bottom portion (36) of said cold section (12) and said top surface (44) of said hot section (14) for providing spacing between said cold section (12) and said hot section (14); and a drive motor (20), said drive motor (20) connecting to said cold section (12) through cold section input (82) for providing rotation to said cold section (12) and said hot section (14).

2. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 1, wherein said lobes are Roots type lobes constructed for positive displacement.

3. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 1, wherein a top surface (66) of said heating jacket (18) closes a bottom portion of said hot section (14).

4. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 3, wherein said heating jacket (18) is formed as a closed hollow chamber through which heated oil is circulated to maintain the temperature of said molten thermoplastic as it is transferred through said pump for melted thermoplastic (10).

5. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 1, including a plurality of said separating pillars (16) extending between said bottom surface (42) of said bottom portion (36) of said cold section (12) and said top surface (44) of said hot section (14).

6. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 5, wherein said separating pillars (16) provide an air gap between said cold section (12) and said hot section (14).

7. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 1, wherein said drive motor 20 is a hydraulic motor that includes feedback sensors to provide operator control of the rotational speed of said drive motor (20), and thus the output of said melted thermoplastic from said pump for melted thermoplastic (10).

8. A pump for melted thermoplastic (10) comprising: a cold section (12) including a top portion (30) and a bottom portion (36) secured together, the cold section having an input (82) to through shafts (22, 24), said through shafts (22, 24) intermeshed, in a space between said top portion (30) and said bottom portion (36) of said cold section, to rotate in opposite directions and having an extended length extending out of a bottom portion of said cold section (12) to a hot section (14); such that each of said through shafts (22, 24) extends outwardly from said cold section (12) to provide rotation to a rotary portion of said hot section (14), at least one separating pillar (16) extending between a bottom surface (42) of said bottom portion (36) of said cold section (12) and a top surface (44) of said hot section (14), thus spacing said cold section (12) from the hot section (14) providing an air gap there between; said hot section (14) including intermeshing lobes (62, 64) counter-rotated by said through shafts (22, 24) to provide positive transfer of a melted thermoplastic; a heating jacket (18) covering a portion of said hot section (14) for heating said hot section (14); and a drive motor (20) for driving said single rotary input of said cold section (12).

9. The pump for melted thermoplastic (10) of claim 8, wherein said lobes (62, 64) are Roots type lobes constructed for positive displacement.

10. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 8, wherein a top surface (66) of said heating jacket (18) closes a bottom portion of said hot section (14).

11. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 10, wherein said heating jacket (18) is formed as a closed hollow chamber through which heated oil is circulated to maintain the temperature of said molten thermoplastic as it is transferred through said pump for melted thermoplastic (10).

12. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 8, including a plurality of said separating pillars (16) extending between said bottom surface (42) of said bottom portion (36) of said cold section (12) and said top surface (44) of said hot section (14), said separating pillars (16) providing said air gap between said cold section (12) and said hot section (14).

13. The pump for melted thermoplastic (10) for transferring and applying thermoplastic material to a road surface of claim 8, wherein said drive motor (20) is a hydraulic motor that includes feedback sensors to provide operator control of the rotational speed of said drive motor, and thus the output of said melted thermoplastic from said pump for melted thermoplastic (10).

14. A method of constructing a pump for melted thermoplastic (10) comprising: providing a cold section (12) including a top portion (30) and a bottom portion (36) secured together, the cold section having an input (82) to through shafts (22, 24), said through shafts (22, 24) intermeshed, in a space between said top portion (30) and said bottom portion (36) of said cold section, to rotate in opposite directions and having an extended length extending out of the bottom portion of said cold section (12) to a hot section (14); providing at least one separating pillar (16) extending between a bottom surface (42) of said bottom portion (36) of said cold section (12) and a top surface (44) of said hot section (14) for providing spacing between said cold section (12) and said hot section (14); connecting a drive motor (20) to said input (82) of said cold section (12) for driving said pump for melted thermoplastic (10) such that said through shafts (22, 24) extends rotational motion from said cold section (12) to said hot section (14) from said drive motor (20) for transfer of melted thermoplastic, said hot section (14) including two intermeshing Roots type lobes (62, 64) connected to a distal end of said through shafts (22, 24) for positive transfer of said melted thermoplastic; connecting a heating jacket (18) to said hot section (14) for heating said hot section (14) of said pump for melted thermoplastic (10).

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a perspective view of the pump for melted thermoplastic;

(2) FIG. 2 is a front view of the pump for melted thermoplastic illustrated in FIG. 1;

(3) FIG. 3 is a left end view of the pump for melted thermoplastic;

(4) FIG. 4 is a right end view of the pump for melted thermoplastic;

(5) FIG. 5 is a top view of the pump for melted thermoplastic;

(6) FIG. 6 is a bottom view of the pump for melted thermoplastic;

(7) FIG. 7 is a partially exploded view of the pump for melted thermoplastic illustrated with the hydraulic motor and the heating jacket exploded from the pump;

(8) FIG. 8 is a partial exploded view illustrating the cold section separated from the hot section;

(9) FIG. 9 is a bottom view of the hot section illustrating the transfer lobes;

(10) FIG. 10 is a top view of the pump for melted thermoplastic illustrated with the hydraulic motor removed;

(11) FIG. 11 is a partial side view, partially in section, illustrated with the hydraulic motor and the heating jacket removed showing the attachment of the separating pillars between the hot and the cold sections;

(12) FIG. 12 is an exploded partial view of the hot section illustrating the packing assembly;

(13) FIG. 13 is a top view of the hot section;

(14) FIG. 14 is a section view taken along lines 14-14 of FIG. 13 illustrating assembly of the packing;

(15) FIG. 15 is a partial exploded view of the lower portion of the cold section;

(16) FIG. 16 is a top view of the lower portion of the cold section;

(17) FIG. 17 is a side view of the lower portion of the cold section;

(18) FIG. 18 is a section view of the lower portion of the cold section taken along lines 18-18 of FIG. 16;

(19) FIG. 19 is an exploded view of the upper portion of the cold section;

(20) FIG. 20 is a top view of the upper portion of the cold section;

(21) FIG. 21 is a section view of the upper portion of the cold section taken along lines 21-21 of FIG. 20;

(22) FIG. 22 is an exploded top view of the heating jacket;

(23) FIG. 23 is a side view of the heating jacket;

(24) FIG. 24 is a bottom view of the heating jacket; and

(25) FIG. 25 is an exploded bottom view of the heating jacket.

DETAILED DESCRIPTION OF THE INVENTION

(26) While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred, albeit not limiting, embodiment with the understanding that the present disclosure is to be considered an exemplification of the present invention and is not intended to limit the invention to the specific embodiments illustrated.

(27) Now referring to FIGS. 1-25, a pump for melted thermoplastic 10 for transferring and applying thermoplastic material to a road surface is illustrated. The pump for melted thermoplastic includes a cold section 12, a hot section 14, a plurality of separating pillars 16, a heating jacket 18, and a drive motor 20. The drive motor 20 connects to the cold section 12 via splined shafting 80 to input 82. It should also be noted that slip shafting or other suitable connection means for providing rotation motion to the pump from a drive motor may be utilized without departing from the scope of the invention. In the preferred embodiment, the drive motor 20 is a hydraulic motor that includes feedback sensors to provide operator control of the rotational speed of the drive motor, and thus the output of the molten thermoplastic from the pump 10. The drive motor 20 connects to a first through shaft 22 through the cold section input 82, which drives a second through shaft 24 via intermeshed spur gears 88. The spur gears 88 may be replaced with any suitable gear combination that provides counter rotation between the two through shafts 22, 24. Seals 26, bearings 28, thrust washers 32 and snap rings 34 are provided in the top portion 30 of the cold section (FIGS. 19-21) for retention of the through shafts. Seals 26, bearings 28, thrust washers 32 and snap rings 34 are also provided in the bottom portion 36 of the cold section (12) (FIGS. 15-18) for retention of the through shafts. In this manner, the spur gears 88 are allowed to float upon the through shafts 22, 24. The top and bottom portions of the cold section 30, 36 are secured together with fasteners 38 and located with dowel pins 40. The through shafts 22, 24 are provided with an extended length extending out of the bottom portion of the cold section 12 to the hot section 14. Separating pillars 16 extend between a bottom surface 42 of the bottom portion 36 of the cold section 12 and the top surface 44 of the hot section 14. The hot section 14 is constructed from a temperature resistant steel and includes inlet port 46 and outlet port 48 along with packing seal assemblies 50 (FIG. 12). The packing seal assemblies 50 include the packing seals 52, gland nuts 54 and gland nut clamps 56. The packing seal assemblies 50 seal the outer diameters of the through shafts 22, 24. Connected to the second ends 58, 60 of the through shafts 22, 24 are transfer lobes 62, 64 oriented on the through shafts to intermesh with each other for transfer of the molten thermoplastic around the inside perimeter 84 of the hot section 14 between the inlet port 46 and the outlet port 48. In a preferred embodiment, the transfer lobes 62, 64 are keyed or splined to the through shafts so that the transfer lobes rotate at the same speed as the through shafts. It should be noted that the preferred embodiment utilizes a Roots type lobe construction for positive displacement. However, other types of lobe, screw or gear constructions may be utilized with less efficiency, desirability and longevity than the Roots type lobe construction without departing from the scope of the invention. The Roots type lobe is particularly desired for its triangular sealing configuration, both at the point of suction and at the point of discharge. The Roots type lobe is also suitable for operation at low pulsation rates, which are particularly desirable for supply of molten plastic to a road marking device. The top surface 66 of the heating jacket 18 closes the bottom portion of the hot section 14. The heating jacket 18 is formed as a closed hollow chamber through which heated oil is circulated to maintain the temperature of the molten thermoplastic as it is transferred through the pump 10. To close the heating jacket 18, a jacket plate 70 is secured to the bottom surface 68 of the upper portion 72 of the heating jacket 18 with fasteners 74. In this manner, heated oil is allowed to circulate through the heating jacket 18 for heating the hot section 14 for transfer to the thermoplastic material. Baffles, tubes, or the like may be added to the interior of the heating jacket 18 to further enhance the heat transfer from the oil to the hot section 14 without departing from the scope of the invention. The heating jacket 18 components are constructed of a material having a suitable heat transfer coefficient so as to transfer heat from the heated oil to the thermoplastic within the hot section 14.

(28) The pump for melted thermoplastic 10 may be mounted on a walk behind system, pulled on a trailer, or built on a vehicle chassis without departing from the scope of the invention. There are various devices that may be attached to the pump for melted thermoplastic 10 to apply molten thermoplastic onto the pavement surface such as, but not limited to, a ribbon dispenser, spray dispensing device, screed extrusion device, or the like, not shown. The ribbon dispenser is heated and suspended above the road surface, applying a forced-extrusion, well-defined thermoplastic line. The spray dispensing device shall result in a thermoplastic spray pattern that is a uniformly thick, well-defined, and securely bonded stripe. The screed extrusion device has a dispensing shoe that rides directly on the road surface, and a continuous line is formed by a three-sided die with a control gate set to a pre-determined thickness. An actuation means, not shown, is in electric communication with the drive motor 20 on the pump for melted thermoplastic 10. The actuation means actuates the drive motor 20 when the pump for melted thermoplastic 10 is needed to dispense molten thermoplastic. Feedback from the drive motor 20 may be supplied electronically to an electronic controller (not shown) to control the speed of the drive motor to coincide with the use of the melted thermoplastic material. The speed of the drive motor 20 may also be combined with feedback from pressure transducers, flow monitors or the like, to prevent overpressure of the pump. Alternatively, a bypass suitable for bypassing of melted thermoplastic materials back to a tank may be utilized without departing from the scope of the invention.

(29) It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention, and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

(30) One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary, and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention, which are obvious to those skilled in the art, are intended to be within the scope of the following claims.