WO2014055099A1

WO2014055099A1 - Concrete mixing apparatus with variable temperature mixing drum and related method for stabilizing a batch of concrete at an optimal temperature

Info

Publication number: WO2014055099A1
Application number: PCT/US2013/000231
Authority: WO
Inventors: Michael L. Rose; T. Michael ROSE
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-10-02
Filing date: 2013-10-02
Publication date: 2014-04-10
Anticipated expiration: 2015-04-02

Description

Title of Invention

CONCRETE MIXING APPARATUS WITH VARIABLE TEMPERATURE MIXING DRUM AND RELATED METHOD FOR STABILIZING A BATCH OF CONCRETE AT AN OPTIMAL TEMPERATURE

Technical Field

[001] This invention relates to concrete mixing and more particularly to concrete mixing systems which employ a rotating concrete mixing drum.

Background Art

[002] Concrete is a mixture of portland cement, water, aggregate (sand and stone), and miscellaneous chemical admixtures. Concrete is mixed at a concrete plant facility and is typically delivered to customers in revolving drum truck mixers, also referred to as concrete trucks or mixer trucks. Concrete is sometimes generically referred to as "ready-mix" because it is ready to use or already mixed upon arrival at a project location.

[003] When a mixer truck arrives at a project location, the concrete batch in the mixing drum must be maintained within a specific temperature range to be usable. Many states have, through sound civil engineering practices, established criteria for the temperature ranges that must be maintained for usable concrete in construction projects. Typically, most standards require that the concrete temperatures at placement be between 50° F and 90° F (10° C and 30° C) except for bridge decks, which should be between 50° F and 80° F (10° C and 27° C). Also, temperature limitations may vary for special application concrete mixes.

[004] If a concrete batch arrives at a project location outside of the specified temperature ranges, it must be rejected. Depending on the concrete design mixture, the rejected batches can be recycled in some instances; in other instances the batch cannot be recycled and is a total loss. Not only is this a loss for the mixing company, but this is also a significant loss for a project's timing schedule because work must be delayed until batches of concrete can arrive having an acceptable temperature. At the construction of the Burj Khalifa tower project in Dubai, UAE, for example, it was estimated that as much as one-third of the concrete arriving at the project site was rejected due to high temperatures.

[005] Another issue arises when concrete batches at different temperatures are applied adjacently at a construction site. While adjacent batches might be in the correct temperature ranges required for an application, nevertheless, if one batch arrives at the lower end of a correct temperature range and a second, adjacent batch arrives at the higher end of the correct temperature range, it has been theorized that such temperature differences can enhance cracking of the concrete, upon curing.

[006] A number of solutions have been attempted to solve the problem of concrete falling outside of acceptable temperature ranges. One simple solution has been to place blocks of ice inside of the mixing drum of a mixing truck on hot days to maintain a lower concrete batch temperature. This solution is not always reliable and can also significantly dilute the concrete mixture.

[007] Another attempt at a solution has come in the form of concrete cooling injection units that inject a cooling fluid from a long wand directly into the drum of a mixing truck. Such representative systems are seen in U.S. Patent Applications 2007/0171764 and 201 1/0198369, both invented by Klein et al. This system is similar to the ice solution in that it introduces a foreign cooling element into the concrete batch mixture and cannot be further regulated beyond the initial injection of cooling fluid.

[008] Concrete plants have recognized the utility of cooling or heating concrete batches. U.S. Patent No. 5,220,732 granted to Lee, discloses a device for cooling rocks and sand to be used as concrete aggregate. This apparatus uses chilled or refrigerated air or gas in a rotary drum device and suggests that the chilled gas can be sprayed directly into the drum. U.S. Patent Application 2002/0001255 shows a portable concrete plant which has a heat exchanger to heat the water used as part of the concrete mixing process undertaken in cold climates. Neither of these devices provides a solution for maintaining a specific temperature range for a batch of concrete contained in a concrete mixing drum.

[009] Concrete mixing drums on trucks have been modified with insulation to provide a heat or cold retaining quality. Russian Patent Publication No. SU417298A discloses a mobile concrete mixer with loading and unloading attachments, a "water measuring system with own heaters" and a mixing drum that appears to be insulated. The water tanks used to supply water to the drum are heated. Japanese Patent Publication No. JP09277245 by Etsuno discloses a concrete drum mixer which consists of a double-walled structure having a honey comb core filled with insulator paste. Such insulated mixing drums would retain heat or cold, but could not regulate the temperature of a batch of concrete ready-mix in transit.

[010] In the area of bioprocessing, mixing drums rotating inside of separate, but adjacent heat exchangers serve to regulate the amount of heat or cold inside of a mixing drum. The heat exchangers contain a heat transfer medium in spirally- arranged tubes to add or remove heat from the batch of concrete contained in the mixing drum. An example of such a device is found in U.S. Patent Application No. 2004/0062140 invented by Cadogan et al. However, this device is not adapted to concrete mixing trucks and with its separate heat exchanger surrounding the mixing drum, would require a complete redesign of existing concrete mixing trucks to implement.

[01 1] U.S. Patent No. 3,946,996 issued to Gergely describes a stationary mixing drum having double walls with a space between the walls for introducing hot liquid or steam to heat an aggregate mixture inside of the drum. The drum remains stationary while a rotatable mixing shaft mixes the aggregate. This drum must be tilted to empty it, which would make it impractical, if not impossible for usage on a concrete mixing truck. With mixing trucks, the entire drum rotates forward to mix, and rotates in reverse to empty; hence to adapt the Gergely design would involve a complete redesign of concrete trucks as they are currently built.

[012] Therefore, a need exists for an apparatus for heating and cooling a batch of concrete contained in a rotatable concrete mixing drum and maintaining the batch of concrete contained inside of the drum within a specified optimal temperature range. Furthermore, a need exists for such an apparatus that could be applied to newly manufactured concrete trucks and also retro-fitted to existing ones.

[013] The foregoing reflects the state of the art of which the inventor is aware, and is tendered with a view toward discharging the inventor's acknowledged duty of candor, which may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing discussion does not teach or render obvious, singly or when considered in combination, the inventor's claimed invention. Summary of the Invention

Technical Problem

[014] Concrete ready-mix must be delivered by concrete mixing trucks to a construction job site within specified temperature ranges in order to be usable, from an engineering standpoint. Concrete batches delivered outside of specified temperature ranges must be rejected, thus resulting in added construction project costs. The invention is an apparatus and method for heating and cooling a batch of concrete contained in a rotatable concrete mixing drum and maintaining the batch of concrete contained inside of the drum within a specified optimal temperature range. The invention can be applied to concrete mixing trucks, thus insuring that batches of concrete are delivered within optimal temperature ranges. The invention also helps insure that concrete batches are delivered at consistent temperatures, thus helping to reduce cracks in cured concrete.

Solution of the Problem

[015] The invention is a concrete mixing apparatus comprising a rotatable concrete mixing drum wherein the apparatus can impart variable temperature control to a batch of concrete contained inside of the mixing drum. In one embodiment, the concrete mixing apparatus is applied to a concrete mixing truck having a rotatable mixing drum. The inventive apparatus allows a batch of concrete to be constantly maintained at an optimal temperature during transit of the concrete batch to a project location. This results in the concrete remaining usable upon arriving at a project location and prevents concrete wastage from rejected concrete batches.

[016] In one embodiment, the inventive concrete mixing apparatus is comprised of a rotatable concrete mixing drum having a series of conduits attached to the drum, the conduits for directing a fluid or gas heat transfer medium. The heat transfer medium is introduced to the conduits through a rotary union which is connected to a heater-chiller unit. The heater-chiller unit can be programmed to achieve a temperature that is optimal for maintaining the concrete batch within acceptable standards. Additional components of the apparatus include a circulating pump for circulating the heat transfer medium and an auxiliary power unit for providing power to the heater-chiller unit at all times.

[017] In a second embodiment of the invention, the heat transfer medium is introduced into at least one conduit band which surrounds the mixing drum. An insulating layer is applied to the mixing drum, and an insulating plug is placed in the concrete flow opening of the drum so as to maintain a controlled temperature environment inside of the mixing drum.

Advantageous Effects of the Invention

[018] Accordingly, the following advantages of the invention apply:

[019] It is an advantage of this invention to provide a concrete mixing apparatus which allows a batch of concrete to be maintained at a desired temperature.

[020] It is another advantage of this invention to provide a concrete mixing apparatus which can be easily adapted to a concrete mixing truck for purposes of maintaining a batch of concrete at a desired temperature while the concrete is in transit.

[021] It is still another advantage of this invention to provide a concrete mixing apparatus capable of regulating the temperature of a batch of concrete contained in a rotatable concrete mixing drum and which can be retro-fitted to existing concrete mixing trucks.

[022] It is another advantage of the invention to provide a concrete mixing apparatus that can be applied to stationary concrete mixing drums.

[023] It is another advantage of this invention to provide a concrete mixing apparatus that can stabilize plural batches of concrete at a desired temperature so that batches arriving at a job site are at consistent stabilized temperature.

[024] Finally, it is another advantage of this invention to provide a method for providing a batch of concrete at a desired stabilized temperature.

[025] Further advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing the preferred embodiments of the invention, without placing limitations thereon.

Brief Description of the Drawings

[026] The invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:

FIG. 1 is a side view of a concrete mixing truck incorporating the present invention.

FIG. 2 is a partial schematic view of the inventive apparatus showing a rotatable concrete mixing drum in accordance with the invention coupled to a rotary union with a programmable heater-chiller unit and associated power unit for the apparatus.

FIG. 3 is a cutaway view of an exhaust heat exchanger for heating the heat transfer medium of the present invention.

FIG. 4 is a plan view of an exemplary programmable interface for the heater- chiller unit of the present invention.

FIG. 5 is a close up cutaway view of the rotary union component of the invention.

FIG. 6 is a cutaway view through a section of the rotatable concrete mixing drum of FIG. 1, in accordance with the invention, showing a batch of concrete ready- mix adjacent the wall of the mixing drum and a series of conduits layered over the exterior surface of the wall of the mixing drum.

FIG. 7 is a cutaway end view of a series of conduits attached to the exterior surface of the wall of a rotatable concrete mixing drum in accordance with the invention.

FIG. 8 is a cutaway end view of an alternative embodiment of a series of conduits attached to the exterior surface of the wall of a rotatable concrete mixing drum in accordance with the invention.

FIG. 9 is a side view of an alternative embodiment of the rotatable concrete mixing drum of the present invention which uses at least one conduit band to regulate the concrete batch temperature inside of the mixing drum.

FIG. 10 is a cross-sectional view through the rotary union of the second embodiment of the rotatable concrete mixing drum introduced in FIG. 9.

FIG. 1 1 is a cross-sectional view through the second embodiment of the rotatable concrete mixing drum introduced in FIG. 9.

FIG. 12 is a close up cross-sectional view of the conduit bands of the second embodiment of the rotatable concrete mixing drum introduced in FIG. 9.

Description of the Embodiments

[027] By way of exemplary embodiments, the inventive concrete mixing apparatus employs a rotatable concrete mixing drum having a means for circulating a heat transfer medium wherein the temperature of the medium can be regulated to keep a batch of concrete contained inside of the mixing drum at an optimal temperature. The heat transfer medium can be a fluid or a gas which is circulated through the apparatus using a pump device. The heat transfer medium circulates through at least one conduit placed in thermodynamic communication with a batch of concrete contained within the rotatable concrete mixing drum. As used herein "thermodynamic" communication means the ability of the heat transfer medium to add heat to the batch of concrete contained in the mixing drum or else to cool the batch of concrete contained in the mixing drum. The concrete mixing apparatus may be maintained as a stationary unit, but is primarily applicable to concrete mixing trucks, of which there are many in existence. The inventive concrete mixing apparatus may be applied to new trucks as part of the manufacturing process or else can be applied as a retro-fit to existing concrete mixing trucks.

[028] Referring to FIG. 1, a first embodiment of the inventive concrete mixing apparatus 10 as applied to a mixing truck 12 is shown. FIG. 2 shows the apparatus 10 by itself, extricated from the remainder of the mixing truck 12 to show the inventive components and flow of the heat transfer medium through the apparatus. As shown, the apparatus 10 is comprised of a rotatable concrete mixing drum 14 preferably having a plurality of conduits 16 extending preferably at least over the downward-most end 18 of the mixing drum 14. The mixing drum 14 of a concrete mixing truck 12 is typically cast at a downward angle as seen in FIG. 1, and the concrete mixture (not shown in this view) would gravitate toward the downward-most end 18 of the drum 14 during transit. Therefore, having the conduits 16 occupy the downward-most end 18 of the drum 14 represents sufficient surface area for the heat transfer medium in the conduits 16 to come into sufficient thermodynamic communication with the batch of concrete so as to affect the temperature of the concrete batch contained within the mixing drum 14.

[029] A heat transfer medium is circulated through the conduits 16. In one embodiment the cooling and heating functions would be accomplished by separate systems present in a programmable heater-chiller unit 20 circulating a liquid heat transfer medium. An exemplary liquid heat transfer medium would be ethylene glycol; other candidates for a liquid heat transfer medium would be propylene glycol, alcohol and water. The heater-chiller unit 20 could operate in its heating function through cycling the heat transfer medium past an immersion heater (not shown) located in the heater-chiller unit 20, in one example. Alternatively the heating function could be achieved through supplying an exhaust heat exchanger which slaves heat from the mixing truck's exhaust system to heat the heat transfer medium. As shown in FIG. 3, the exhaust (note large arrows indicating exhaust flow) is slaved from the exhaust pipe 23 and piped into a heat exchanger 25 comprised of coils 27 containing the heat transfer medium (note small arrows indicating direction of flow of heat transfer medium through coils 27). The heat transfer medium is cycled through the heat exchanger 25 and heated to a hot temperature wherein it is cycled into the conduits 16 of the mixing drum 14.

[030] The cooling function could likewise pass the heat transfer medium through a refrigeration-type chiller (not shown) located in the heater-chiller unit 20. The refrigeration-type chiller of the heater-chiller 20 would be similar to chiller units used on reefer trucks. Some exemplary truck reefer units which could be modified and applied to mixer trucks can be found at the following website from Klinge Corporation: http://www.klingecorp.com/refrigeration-units/tank-container- refrigeration-heating/. If ethylene glycol is used as a heat transfer medium, it could be sourced from a single reservoir wherein the heat transfer medium is either heated, or cooled by the heater-chiller unit 20 to achieve a desired concrete batch temperature.

[031] The programmable heater-chiller unit 20 would be in communication with at least one temperature sensor located inside of the rotatable concrete mixing drum 14 which would relay the temperature of the batch of concrete ready-mix material to the programmable heater-chiller unit 20. The temperature sensor (not shown) could take the form of a stationary probe extending inside the drum 14 in line with the rotary union 22 and relay temperature information through the rotary union 22 to the programmable heater-chiller unit 20. The temperature sensor would preferably be coated with Teflon or other non-stick coating to prevent buildup of concrete on the sensor. Good practice would require that when the mixing drum 14 is cleaned, that the sensor be washed off as well, to maintain optimum sensor performance.

[032] The programmable heater-chiller unit 20 would be controlled by the mixing truck driver and could be programmed inside of the truck cab through a programmable interface to maintain a batch of concrete ready-mix at an optimal stabilized temperature or at least within a stabilized temperature range while in transit. If the temperature of the ready mix begins to increase to a less optimal trajectory, the cooling function of the apparatus would be actuated by the programmable heater- chiller unit 20; if the temperature of the ready mix begins dropping along a less optimal trajectory, the heating function would be actuated by heater-chiller unit 20.

[033] The programmable interface 31 for the heater-chiller unit 20 is shown in FIG. 4 and would be preferably mounted in the cab of the mixer truck 12 at a location accessible and visible to the driver. Preferably, the programmable interface 31 is fairly simplistic; having minimal switches and indicators necessary for maintaining the concrete in the mixing drum 14 at the optimal desired stabilized temperature. The programmable interface includes a computer processor (not shown) and information storage means (not shown), such as a hard drive, to manage and record various concrete batch temperatures at time of delivery. The concrete temperature is shown on an LED screen 33, and the temperature can be set with touch-sensitive switches 35 for increasing and decreasing the indicated desired temperature shown on LED screen 37. An LED screen 39 indicating time to reach the desired stabilized temperature will aid a driver in timing the delivery of a batch of concrete so that it is at the desired stabilized temperature upon reaching a delivery destination. An LED screen 41 indicating the amount of concrete left in the mixing drum could be in communication with a weight sensor attached to the drum. A small printer 51 could provide a printed hard copy readout of the temperatures of all concrete batches delivered for various customers at time of delivery. Alternatively, the temperature information could be downloaded wirelessly 53 from each mixing truck at various times of the day or else downloaded to a solid digital media such as a USB thumb drive from a USB port 55. A keyboard (not shown) could be attached to the interface to add further notations to a delivery record, if desired. Finally, an on/off switch 43 is indicated on the interface 31 for activating and deactivating the heater- chiller unit 20.

[034] One or more pumps, which could be part of the heater-chiller unit 20, circulate the heat transfer medium through the conduits 16. The pump(s) would be powered by a separate auxiliary power unit 24. In the preferred embodiment, the power unit 24 would use an approximately 10 KW hydraulic motor and generator combination to provide electric power at 1 10 or 220 volts AC. It is possible that a mixing truck's existing hydraulic pumping system could provide power to run the hydraulic motor and generator combination of power unit 24. Power unit 24 would run a refrigeration-type chiller of the heater-chillier unit 20 to cool the heat transfer medium in hot weather applications and further power an immersion heater (located in the heater-chiller unit) to heat the heat transfer medium, when needed.

[035] Referring to FIG. 5, the rotary union 22 of the invention can be explained more fully. The heat transfer medium is pumped from the heater-chiller unit 20 into the conduits 16 of the mixing drum 14 using a specialized rotary union 22. The rotary union allows for the free flow of heat transfer medium into, and out of the conduits 16 of the rotary concrete mixing drum 14. FIGS. 2 and 5 shows an inlet 26 in rotary union 22 for introducing the heat transfer medium (see direction of arrows representing flow of heat transfer medium in FIG. 2) to the conduits 16 of mixing drum 14. An outlet 28 allows for the exit of the heat transfer medium from the rotary union 22. An exemplary rotary union envisioned by the inventor could be sourced from Rotary Systems, Inc. at www.rotarvsvstems.com with appropriate modifications for purposes of this invention.

[036] Referring now to FIG. 6, a cutaway of the rotatable concrete mixing drum 14 of FIG. 1 is shown. This view shows a batch 30 of ready-mix concrete as it might appear in the mixing drum, the concrete batch 30 contacting the wall 32 of the mixing drum. The conduits 16 which conduct the heat transfer medium are also shown. When the conduits 16 are filled with heat transfer medium, the heat transfer medium is in thermodynamic communication with the batch 30 of concrete as shown. If the heat transfer medium is at a higher temperature than the batch 30 of concrete, it will transfer heat to the batch through the mixing drum wall 32. Conversely, if the heat transfer medium is at a lower temperature than the batch 30, it will draw heat from the batch 30 through wall 32 and cool the batch down.

[037] The invention achieves this arrangement of conduits 16 shown in FIG. 6 by a method known as "dimpling." This method involves a step of forming a sheet of stainless steel 36 or other metal against the steel wall 32 of the mixing drum 14. The stainless steel sheet 36 is then spot-welded to the steel mixing drum 14 in a plurality of locations so that a series of spot-welds 38 arrayed in uniform lines are achieved across the formed stainless steel layer 36. The stainless steel layer 36 would cover at least the downward end 18 of the rotatable concrete mixing drum 14 shown in FIG. 1, but in excessively cold or hot climates, covering the entire concrete mixing drum 14 with conduits 16 may be desirable to maximize heating or cooling effect. When the spot-welding process is complete, the sheet 36 is welded at any open locations (e.g. along the edges of the sheet) to close them up. An opening is kept clear to introduce air at high pressure, the result being that the areas 40 between the spot-welds 38 are "blown out" to create the conduits 16 shown in FIGS. 6 and 7. This method of producing conduits 16 on the mixing drum 14 can be applied to both new and existing concrete mixing drums. Therefore, existing trucks can be retrofitted to have the inventive apparatus 10 applied to them. [038] FIG. 8 represents an alternative conduit structure 45 that offers an alternative to the dimpling process, yet still maintains the heat transfer medium in thermodynamic communication with a batch of concrete contained in the rotatable mixing drum 14. The structure shown would be pre-manufactured and then applied to the exterior surface of wall 32 of the mixing drum 14 and welded in place. As shown the conduits 42 are formed using an upper sheet 44 of stainless steel and a lower sheet 46 of stainless steel. The upper and lower sheets would be formed in a press separately then spot welded together to form the conduit structure 45 shown. The entire structure 45 would then be welded to the outside exterior surface of wall 32 of mixing drum 14. This alternative conduit structure may be easier to apply to retro-fit drums than the embodiment of the conduit structure shown in FIGS. 6 and 7.

[039] Referring now to FIG. 9, an alternative embodiment 47 of the inventive apparatus showing a concrete mixing drum 48 surrounded by conduit bands 50, 52 is shown. Conduit bands 50, 52 are constructed in the pre-manufactured manner shown and described for FIG. 8. The conduit bands 50, 52 surround the entire mixing drum 48 and have an inlet side 54 and an outlet side 56. The inlet side 54 is separated from the outlet side 56 by a barrier 58, which can be a sealing weld. Hydraulic hoses 60, 62, 64 carry a heat transfer medium in a cycling fashion from the rotary union 66, into the conduit bands 50, 52 and back out to the rotary union 66 which then cycles the heat transfer medium back to the heater/chiller unit 20. In a preferred two-band arrangement as shown in FIG. 9, a first hydraulic hose 60 carries the heat transfer medium (note arrows) from the rotary union 66 to the first conduit band 50. A second hydraulic hose 62 serves as a conduit carrying the heat transfer medium (note arrow) from an outlet side 56 of the first conduit band 50 to an inlet side 54 of the second conduit band 52. As such, the second hydraulic hose 62 crosses over the barrier 58 of the conduit bands 50, 52. A third hydraulic hose 64 carries the heat transfer medium from an outlet side 56 of the second conduit band 52 back to the rotary union 66. If a single, conduit band is used, then the second hydraulic hose 62 would be eliminated and only two hoses, one feeding the inlet side and one relieving the outlet side of the single conduit band would be needed. If one conduit band is used, it is preferable that it be between approximately two to three feet in width to provide sufficient temperature-altering thermodynamic communication. If the preferable two bands are used, each band should be between approximately one and two feet in width. [040] Referring now to FIG. 10, the design of the rotary union 66 in accordance with the embodiment of FIG. 9 is shown in cutaway view. The rotary union 66 employs a rotating section 68 that is in sealing relation to a stationary section 70. The rotating section 68 rotates freely and is attached to the rotatable concrete mixing drum 48. The sealing relation of the rotating section 68 with the stationary section 70 insures that a fluid heat transfer medium such as ethylene glycol will not leak from the rotary union 66. An inlet 72 in the stationary section 70 introduces the heat transfer medium to a conduit 74 which conducts the heat transfer medium to an outlet 76 in the rotary section 68. The outlet 76 in the rotary section 68 feeds the inlet hydraulic hose 60 of the conduit band 50. The outlet hydraulic hose 64 of the conduit band 52 feeds the inlet 78 of the rotating section 68. A second conduit 79 conducts the heat transfer medium back through the stationary section 70 until it exits the stationary section at outlet 82 to recycle back to the heater-chiller unit 20. The rotary union 66 as described here allows the mixing drum 48, conduit bands 50, 52 and hydraulic hoses 60, 62, 64 to rotate together during the concrete mixing process.

[041] Referring to FIGS. 1 1 and 12, a cross section through the rotary concrete mixing drum 48 of the second embodiment is shown. The conduits 42 of the conduit bands 50, 52 are shown. The conduit bands 50, 52 are located near the low point 86 of the mixing drum 48, so as to assure the maximum transference of heat or cold to any batch of ready-mix concrete, which happens to be contained in the mixing drum 48. The conduits 42 would be filled with a heat transfer medium such as ethylene glycol when the invention is in operation.

[042] Still referring to FIGS. 1 1 and 12, the mixing drum 48 is supplied with an insulating layer 88 as shown. The insulating layer 88 is placed on the outside of the mixing drum wall 90 and over the outer surface of the conduit bands 50, 52. Insulation helps prevent excessive heat transfer from ambient air in hot climates and also prevents the transfer of heat to surrounding frigid air in cold climates. The insulating layer can be comprised of a spray-on foam of approximately ½" to 2" thick; an adhesive foam blanket; or an insulating paint such as one of the super-insulating paints containing micro-glass spheres that are typically sprayed on in built-up layers of approximately .05" to .10" per layer, to an ultimate thickness of .25" to 1 " thick.

[043] FIG. 1 1 also illustrates the addition of an insulating plug 92 for placement in the concrete flow opening 94 of the rotary concrete mixing drum 48. The composition of the insulating plug 92 can be of a durable foam compound, for example. The addition of the insulating plug 92 more easily creates a regulated temperature-controlled environment inside of the mixing drum 48 that is less prone to wide swings in temperature due to the ambient environment heat and cold. The inventor has found that the use of the insulating plug 92 in combination with the insulating layer 88 allows the size of the heater-chiller unit 20 to be reduced by a factor of ten. A heat reflective top coat 89 could also be added to further reduce the effects on batch temperature due to thermal gain from solar radiation on hot days and reducing radiant heat loss in extremely cold weather.

[044] Finally, although the description above contains much specificity, this should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. This invention may be altered and rearranged in numerous ways by one skilled in the art without departing from the coverage of any patent claims, which are supported by this specification.

Industrial Applicability

[045] The invention has industrial applicability to stationary concrete mixers, but has special applicability to the vehicle industry regarding existing and new concrete mixer trucks. The invention can be applied to new mixer trucks, and also discloses embodiments that are useful for retro-fitting to existing concrete mixer trucks.

Reference Signs List

[046]

First Embodiment of Apparatus, Generally - 10

Mixing Truck - 12

Concrete Mixing Drum - 14

Conduits - 16

Downward End of Concrete Mixing Drum -18

Heater-Chiller Unit - 20

Rotary Union - 22

Exhaust Pipe - 23

Auxiliary Power Unit - 24

Heat Exchanger - 25

Rotary Union Inlet - 26 Coils in Heat Exchanger - 27

Rotary Union Outlet - 28

Ready-Mix Concrete - 30

Programmable Heater-Chiller Interface - 31

Concrete Mixing Drum Wall - 32

LED Screen of Programmable Heater-Chiller Interface - Concrete Temperature - 33 Temperature Control Touch Switches of Programmable Heater-Chiller Interface - 35 Stainless Steel Sheet Material - 36

LED Screen of Programmable Heater-Chiller Interface - Desired Temperature - 37 Spot Welds - 38

LED Time Screen of Programmable Heater-Chiller Interface - 39

Conduits in Alternate Embodiment Conduit Structure - 42

On-Off Switch of Programmable Heater-Chiller Interface - 43

Alternative Embodiment Conduit Structure Sheet - 45

Alternate Apparatus Embodiment, Generally, with Conduit Bands - 47

Concrete Mixing Drum of Alternate Apparatus Embodiment - 48

Conduit Bands - 50, 52

Inlet Side of Conduit Bands - 54

Outlet Side of Conduit Bands - 56

Barrier Between Inlet and Outlet Sides - 58

Hydraulic Lines - 60, 62, 64

Rotary Union - 66

Rotating Section of Rotary Union - 68

Stationary Section of Rotary Union - 70

Inlet in Stationary Section - 72

Conduit - Rotary Unit - 74

Outlet - Rotating Section - 76

Inlet - Rotating Section - 78

Conduit - Rotary Unit - 79

Outlet - Stationary Section - 82

Low Point of Concrete Mixing Drum - 86

Insulating Layer - 88

Concrete Mixing Drum Wall - 90

Insulating Plug - 92 Flow Opening of Mixing Drum - 94

Reference to Deposited Biological Material

[047] Not Applicable

Sequence Listing Free Text

[048] Not Applicable

Citation List

Patent Literature

[049]

U.S. Patent Application 2007/0171764 (Klein et al.)

U.S. Patent Application 201 1/0198369 (Klein et al.) U.S. Patent No. 5,220,732 ( Lee)

U.S. Patent Application 2002/0001255 (Flood et al.)

U.S. Patent Application 2004/0062140 (Cadogan et al.)

U.S. Patent No. 3,946,996 (Gergely)

Russian Patent Publication No. SU417298A

Japanese Patent Publication No. JP09277245 (Etsuno)

Non-Patent Literature

[050] Not Applicable

Claims

1. A concrete mixing apparatus for maintaining a batch of concrete at a desired temperature, comprising:

a rotatable concrete mixing drum;

a heat transfer medium;

wherein said concrete mixing drum further comprises at least one conduit for conducting said heat transfer medium into thermodynamic communication with said batch of concrete contained in said mixing drum;

means for heating said heat transfer medium;

means for cooling said heat transfer medium:

and

a rotary union, said rotary union conducting said heat transfer medium to said at least one conduit of said concrete mixing drum.

2. The concrete mixing apparatus as recited in claim 1 , wherein said rotary union further comprises a rotating section attached to said rotatable concrete mixing drum and a stationary section, said stationary section remaining static in relation to said rotating section when said rotating section and rotatable concrete mixing drum are in rotation.

3. The rotary union of the concrete mixing apparatus as recited in claim 2, wherein said rotating section of said rotary union further comprises an inlet and an outlet for conducting said heat transfer medium during rotation of said rotatable mixing drum.

4. The concrete mixing apparatus as recited in claim 1 , wherein said heat transfer medium is ethylene glycol.

5. The concrete mixing apparatus as recited in claim 1 , wherein said apparatus is mounted on a concrete mixing truck.

6. The concrete mixing apparatus as recited in claim 1, wherein said means for heating said heat transfer medium is an immersion heater.

7. The concrete mixing apparatus as recited in claim 5, wherein said means for heating said heat transfer medium is a vehicle exhaust heat exchanger.

8. The concrete mixing apparatus as recited in claim 1, wherein said means for cooling said heat transfer medium is a refrigeration-type chiller

9. The concrete mixing apparatus as recited in claim 1, wherein said means for heating said heat transfer medium and means for cooling said heat transfer medium are combined into a heater-chiller unit.

10. The concrete mixing apparatus as recited in claim 9, wherein said heater- chiller unit is programmable.

1 1. The concrete mixing apparatus as recited in claim 9, further comprising a programmable interface, said programmable interface providing means for indicating a temperature of a batch of concrete and means for programming a desired concrete batch temperature.

12. The concrete mixing apparatus as recited in claim 1 1, wherein said programmable interface has computer processor means for recording and outputting a record of a concrete batch temperature at time of delivery of a concrete batch.

13. The concrete mixing apparatus as recited in claim 12, wherein said outputted record from said programmable interface is selected from a group consisting of a hard copy record, a digital record and a wirelessly transmitted record.

14. The concrete mixing apparatus as recited in claim 1 1, wherein said programmable interface further comprises means for indicating a time required for a batch of concrete to reach said desired concrete batch temperature.

15. The concrete mixing apparatus as recited in claim 1, wherein said at least one conduit for conducting said heat transfer medium is created using a dimpling method.

16. The concrete mixing apparatus as recited in claim 1 , wherein said at least one conduit for conducting said heat transfer medium is contained in at least one conduit band.

17. The concrete mixing apparatus as recited in claim 1 , wherein said at least one conduit for conducting said heat transfer medium is created by pre-forming a conduit structure and attaching said conduit structure to a wall of said rotatable concrete mixing drum.

18. The concrete mixing apparatus as recited in claim 1 , wherein said rotatable mixing drum further comprises an insulating layer.

19. The concrete mixing apparatus as recited in claim 18, wherein said insulating layer is comprised of spray-on foam insulation.

20. The concrete mixing apparatus as recited in claim 18, wherein said insulating layer is comprised of an adhesive foam blanket.

21. The concrete mixing apparatus as recited in claim 18, wherein said insulating layer is comprised of a super-insulating paint.

22. The concrete mixing apparatus as recited in claim 21, wherein said super- insulating paint is further comprised of micro glass spheres.

23. The concrete mixing apparatus as recited in claim 1 , further comprising an insulating foam plug placed in a concrete flow opening of the rotatable concrete mixing drum.

24. A method for stabilizing the batch temperature of a batch of concrete contained inside of a rotatable concrete mixing drum, the method comprising:

(a) loading a batch of concrete into a rotatable concrete mixing drum;

(b) placing a heat transfer medium in thermodynamic communication with said batch of concrete contained in said rotatable concrete mixing drum so as to affect the temperature of said batch of concrete contained in said rotatable concrete mixing drum;

(c) providing a means for heating said heat transfer medium;

(d) providing a means for cooling said heat transfer medium;

(e) providing a rotary union attached to said rotatable concrete mixing drum, wherein said rotary union facilitates the cycling of said heat transfer medium into thermodynamic communication with said batch of concrete contained in said rotatable concrete mixing drum during rotation of said concrete mixing drum; and

(f) maintaining said heat transfer medium in thermodynamic communication with said batch of concrete contained in said rotatable concrete mixing drum until said batch of concrete contained inside of said rotatable concrete mixing drum is stabilized at a desired batch temperature.

25. A concrete mixing apparatus for maintaining a batch of mixed concrete at a desired temperature, comprising:

a rotatable concrete mixing drum;

at least one conduit band attached to said rotatable concrete mixing drum;

a heat transfer medium, said heat transfer medium cycling through said at least one conduit band.

said heat transfer medium being in thermodynamic communication with a batch of concrete contained in said concrete mixing drum while said heat transfer medium is cycling through said conduit band;

means for heating said heat transfer medium;

means for cooling said heat transfer medium;

and a rotary union, said rotary union conducting said heat transfer medium to said at least one conduit band of said concrete mixing drum.

26. The concrete mixing apparatus as recited in claim 25, wherein said rotary union further comprises a rotating section attached to said rotatable concrete mixing drum and a stationary section, said stationary section remaining static in relation to said rotating section when said rotating section and rotatable concrete mixing drum are in rotation.

27. The rotary union of the concrete mixing apparatus as recited in claim 26, wherein said rotating section of said rotary union further comprises an inlet and an outlet for conducting said heat transfer medium during rotation of said rotatable mixing drum.

28. The concrete mixing apparatus as recited in claim 25, wherein said heat transfer medium is ethylene glycol.

29. The concrete mixing apparatus as recited in claim 25, wherein said apparatus is mounted on a concrete mixing truck.

30. The concrete mixing apparatus as recited in claim 25, wherein said means for heating said heat transfer medium is an immersion heater.

31. The concrete mixing apparatus as recited in claim 29, wherein said means for heating said heat transfer medium is a vehicle exhaust heat exchanger.

32. The concrete mixing apparatus as recited in claim 25, wherein said means for cooling said heat transfer medium is a refrigeration-type chiller

33. The concrete mixing apparatus as recited in claim 25, wherein said means for heating said heat transfer medium and means for cooling said heat transfer medium are combined into a heater-chiller unit.

34. The concrete mixing apparatus as recited in claim 33, wherein said heater- chiller unit is programmable.

35. The concrete mixing apparatus as recited in claim 33, further comprising a programmable interface, said programmable interface providing means for indicating a temperature of a batch of concrete and means for programming a desired concrete batch temperature.

36. The concrete mixing apparatus as recited in claim 35, wherein said programmable interface has computer processor means for recording and outputting a record of a concrete batch temperature at time of delivery of a concrete batch.

37. The concrete mixing apparatus as recited in claim 36, wherein said outputted record from said programmable interface is selected from a group consisting of a hard copy record, a digital record and a wirelessly transmitted record.

38. The concrete mixing apparatus as recited in claim 35, wherein said programmable interface further comprises means for indicating a time required for a batch of concrete to reach said desired concrete batch temperature.

39. The concrete mixing apparatus as recited in claim 25, wherein said at least one conduit for conducting said heat transfer medium is created using a dimpling method.

40. The concrete mixing apparatus as recited in claim 25, wherein said at least one conduit for conducting said heat transfer medium is created by pre-forming a conduit structure and attaching said conduit structure to a wall of said rotatable concrete mixing drum.

41. The concrete mixing apparatus as recited in claim 25, wherein said rotatable mixing drum further comprises an insulating layer.

42. The concrete mixing apparatus as recited in claim 41, further comprising a heat-reflective top coat applied to said insulating layer.

43. The concrete mixing apparatus as recited in claim 42, wherein said insulating layer is comprised of spray-on foam insulation.

44. The concrete mixing apparatus as recited in claim 42, wherein said insulating layer is comprised of an adhesive foam blanket.

45. The concrete mixing apparatus as recited in claim 42, wherein said insulating layer is comprised of a super-insulating paint.

46. The concrete mixing apparatus as recited in claim 45, wherein said super- insulating paint is further comprised of micro glass spheres.

47. The concrete mixing apparatus as recited in claim 25, further comprising an insulating foam plug placed in a concrete flow opening of the rotatable concrete mixing drum.