Abstract:
A supplemental heating apparatus for use in conjunction with the coolant system of a truck engine provides a supplemental source of heat energy to the heat exchanger within a tanker trailer. The supplemental heating apparatus is activated when the truck engine is shut-off. A control system undertakes a testing cycle in which a circulator pulls coolant out of the tanker trailer and the temperature of the coolant is sensed after a delay of time so that the coolant from within the heat exchanger is tested. The burner draws fuel from the truck&#39;s fuel tanks to provide heat energy when the sensed temperature is below a threshold. The coolant is circulated between the boiler associated with the burner and the heat exchanger until the return coolant is raised above a second threshold. The testing cycle continues through a loop of a predetermined duration independent of the activation of the heating cycle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims domestic priority on U.S. Provisional Application Ser. No. 61/118,507, filed on Nov. 28, 2008, and entitled “Transport Heater for Tanker Trailers”, the content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is directed generally to the heating of materials transported in liquid form in tanker trailers, and particularly, to a heating apparatus that is operable to provide supplemental heat to the liquid material within the tanker trailer to maintain the temperature of the material within a preferred range. 
       BACKGROUND OF THE INVENTION 
       [0003]    Transporting certain materials, such as chocolate, require that the material be maintained in a liquid form so that the material can be discharged from the tanker for delivery thereof. Presently, the liquid material is maintained within the desired temperature range by coupling a heat exchanger within the tanker to the engine coolant system of truck pulling the tanker trailer. Heat is then diverted from the engine into the heat exchanger to maintain the desired temperature. 
         [0004]    Regulations require long distance truckers to rest for prescribed periods during which the truck engine is continued to run so that the heating of the liquid material within the tanker trailer can be maintained. Such continued operation of the truck engine while the truck is not moving along the highway is expensive and wasteful in terms of fuel expended and extended maintenance of the engine, and is environmentally unfriendly. Furthermore, some governmental entities, including municipalities, counties and states, are adopting legislation that will limit the length of time that a truck can be idled while the operator is resting. While such legislation is intended to reduce vehicle emissions, the engine can no longer generate heat to maintain the temperature of the temperature-sensitive food products. 
         [0005]    Accordingly, it would be desirable to provide a heating apparatus that can be utilized to provide supplemental heat to the tanker trailer while the truck engine is shut down. It would also be desirable to provide a heating apparatus that will be operable to maintain the desired temperature of temperature-sensitive food products or other liquid materials in a manner that is less costly than continuing the idled operation of the truck engine while the truck is not being moved along the highway. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of this invention to overcome the disadvantages of the prior art by providing a supplemental heating apparatus to supply heat energy to a heat exchanger within a tanker trailer when the heat exchanger is not capable of obtaining heat energy from the truck. 
         [0007]    It is another object of this invention to provide a supplemental heating apparatus that is selectively operable to provide heat energy to a heat exchanger in a tanker trailer to maintain the desired temperature of material carried within the tanker trailer. 
         [0008]    It is a feature of this invention that the supplemental heating apparatus can be activated when the truck engine is turned off and can no longer provide a source of heat energy for the tanker trailer. 
         [0009]    It is an advantage of this invention that the operation of the supplemental heating apparatus is substantially less expensive and more environmentally friendly than continuing the operation of the truck engine to supply heat energy for the tanker trailer while the truck and tanker trailer are not being moved across the highway. 
         [0010]    It is another feature of this invention that the control system for the supplemental heating apparatus periodically samples the coolant circulated from the heat exchanger to determine if the material within the tanker trailer has cooled to a predetermined temperature. 
         [0011]    It is still another feature of this invention that the control system will activate a heating cycle when the control system senses a temperature in said coolant below the predetermined temperature. 
         [0012]    It is another advantage of this invention that the control system utilizes a predetermined delay before sensing the temperature of the coolant being circulated by the supplemental heating apparatus. 
         [0013]    It is still another object of this invention to provide a supplemental heating apparatus that utilizes the fuel and electrical energy from supplies thereof carried by said truck. 
         [0014]    It is yet another object of this invention to provide a supplemental heating apparatus that would be operable to provide a source of heating energy while the truck is circulating heated coolant to the heat exchanger within the tanker trailer. 
         [0015]    It is still another feature of this invention that the control system goes through a test cycle irrespective of whether the burner assembly is being operated to provide heat energy to be transferred to the heat exchanger. 
         [0016]    It is yet another feature of this invention that the control system activates a heating cycle when the temperature of the material in the tanker trailer drops below a predetermined threshold. 
         [0017]    It is still another advantage of this invention that the test cycle continues to operate on its predetermined frequency even when the heating cycle has been activated. 
         [0018]    It is yet another advantage of this invention that the test cycle incorporates a predetermined delay in checking the temperature of the coolant being circulated into the supplemental heating apparatus to obtain a reading of the temperature of the material within the tanker trailer. 
         [0019]    It is a further object of this invention to provide a supplemental heating apparatus, and a method of operating the supplemental heating apparatus, to provide heat energy to a the contents of a tanker trailer, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
         [0020]    These and other objects, features and advantages are accomplished according to the instant invention by providing a supplemental heating apparatus for use in conjunction with the coolant system of a truck engine to provide a supplemental source of heat energy to the heat exchanger within a tanker trailer. The supplemental heating apparatus is activated when the truck engine is shut-off. The control system undertakes a testing cycle in which a circulator pulls coolant out of the tanker trailer and the temperature of the coolant is sensed after a delay of time so that the coolant from within the heat exchanger is tested. The burner draws fuel from the truck&#39;s fuel tanks to provide heat energy when the sensed temperature is below a threshold. The coolant is circulated between the boiler associated with the burner and the heat exchanger until the return coolant is raised above a second threshold. The testing cycle continues through a loop of a predetermined duration independent of the activation of the heating cycle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0022]      FIG. 1  is a side elevational view of a truck and tanker trailer having a supplemental heating apparatus incorporating the principles of the instant invention; 
           [0023]      FIG. 2  is an enlarged partial side elevational view of the truck and tanker trailer of  FIG. 1 , showing the transport heater apparatus incorporating the principles of the instant invention; 
           [0024]      FIG. 3  is a perspective view of the housing shell protecting the heating apparatus from the environment; 
           [0025]      FIG. 4  is a rear perspective view of the transport heating apparatus and control assembly incorporating the principles of the instant invention; 
           [0026]      FIG. 5  is a front perspective view of the transport heating apparatus and control assembly; 
           [0027]      FIG. 6A  is a logic flow diagram for the testing loop portion of the operating controls of the transport heating apparatus; and 
           [0028]      FIG. 6B  is a logic flow diagram for the heating loop portion of the operating controls of the transport heating apparatus, the combination of  FIGS. 6A and 6B  depicting the operating logic for the transport heating apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Referring to the drawings, a transport heating apparatus incorporating the principles of the instant invention can best be seen. The truck  10  is conventionally operable to pull a tanker trailer  15  that is filled with a temperature-sensitive material, such as chocolate. The conventional heating system for the tanker trailer  15  utilizes a heat exchanger  16  within the tanker trailer  15  that is coupled in flow communication with the coolant system for the engine  12  via conduits  18 ,  19  that circulate engine coolant from the engine  12  to the heat exchanger  16  and return to the engine  12  while the engine  12  is operating. A valve (not shown) is operable to circulate the engine coolant when the temperature of the material within the tanker trailer  15  drops below a predefined threshold, or in a manual configuration when the operator feels additional heat is needed in the tanker trailer. 
         [0030]    As best seen in  FIGS. 1 and 2 , the transport heating apparatus  20  is mounted on a truck  10  or on a tanker trailer  15  and is connected to the engine  12  of the truck  10  to supplement the conventional heating operation provided to the tanker trailer  15 . Specifically, the transport heating apparatus  20  is tapped into the conduits  18 ,  19  that transfer engine coolant to and from the heat exchanger  16  within the tanker trailer  15 . The primary purpose of the transport heating apparatus  20  is to provide heat to maintain the desired temperature of the temperature-sensitive material within the tanker trailer  15  while the engine  12  is not operating. Alternatively, the transport heating apparatus  20  can supplement the supply of heat to the heat exchanger  16  while the truck is being operated. In some cold climates, the heat requirements to maintain the desired temperature of the material within the tanker trailer  15  is sufficiently high that the operator&#39;s cab  13  cannot obtain sufficient heat from the coolant to maintain a comfortable operating environment within the operator&#39;s cab  13 . In such cases, the supplemental heat provided by the transport heating apparatus  20  will facilitate the maintenance of a comfortable environment within the operator&#39;s cab  13 . 
         [0031]    The components of the transport heating apparatus  20  are best seen in  FIGS. 3-5 . To protect the transport heating apparatus  20  from the environment while being transported on the truck  10  or trailer  15 , a housing shell  21  is provided to cover the heating apparatus  20 . The housing shell  21  is detachably connected to and, preferably, sealed against the base member  22  supporting most of the remaining components of the transport heating apparatus  20 . On the base member  22  is mounted a conventional burner  25  that is operable to ignite and burn #2 diesel fuel, which is carried by the truck  10  to provide fuel for the operation of the engine  12 . Accordingly, the transport heat apparatus  20  has a fuel line  26  that is coupled in flow communication to the fuel tanks  14  of the truck  10  to be able to draw fuel therefrom into the burner  25  to create heat energy. The burner  25  is also provided with an exhaust line  27  that is operable to discharge combustion gases from the burner  25  to the atmosphere when the burner  25  is operating to create heat energy. 
         [0032]    The burner  25  has a boiler  28  that is connected to a coolant supply line  29  and a coolant return line  29   a  that is coupled in flow communication with the conduits  18 ,  19 , respectively, to draw engine coolant from the coolant return conduit  19  via the coolant supply line  29  into the boiler  28  to be heated and then returned to the coolant supply conduit  18  for delivery to the heat exchanger  16  in the tanker trailer  15 . In this manner, the heat energy created by the transport heating apparatus  20  can be used to supplement the heat provided by the operating engine, or to maintain the desired temperature of the material in the trailer while the engine  12  is not operating. 
         [0033]    The controls for the operation of the transport heating apparatus  20  are shown in  FIGS. 4 and 5 , and explained in the logic flow diagram of  FIG. 6 . The control mechanism  30  is powered through an electrical connection  31  with the electrical system of the truck  10 , which includes a battery  11 , which can be a separate battery provided for the operation of the control mechanism  30 , rather than utilize the electrical energy stored by the battery used for the starting of the truck  10 . By providing a separate battery  11  for the operation of the transport heating apparatus  20 , the draw of electrical current for the operation of the transport heating apparatus  20  will not endanger the starting of the engine  12 . Preferably, the battery charging system of the engine  12  will be coupled to the battery  11  to recharge the battery  11  when the engine  12  is operating. 
         [0034]    The control mechanism  30  includes a circulator  32  that is electrically powered and operable to circulate engine coolant from the coolant return conduit  19  through the coolant supply line  29  into the boiler  28  to be heated by the heat energy created from the burning of fuel therein, and returned to the coolant supply conduit  18  via the coolant return line  29   a.  The control mechanism also includes a temperature switch  33 , a relay  34  a cycle timer  35  and a delay timer  36 , all coupled electrically to the circulator  32  and to the burner  25  to control the operation thereof, as is described in greater detail below and shown in the logic flow diagram of  FIG. 6 . Preferably, the control mechanism  30  also includes an on/off switch (not shown) accessible by the operator within the operator&#39;s cab  13  when the operation of the transport heating apparatus  20  is desired, such as when the operator is about to shut down the engine  12  for an extended period of time, or when the operator is not getting sufficient heat from the heating system within the operator&#39;s cab  13 . 
         [0035]    As shown in  FIG. 6 , when the operator turns on the control system  30  at step  41 , the cycle timer  35  starts it sequence at step  42 . The circulator  32  begins to draw coolant from the coolant return conduit  19  into the boiler  28  and back out through the coolant return line  29   a  to the coolant supply conduit  18 . This movement of the coolant by the circulator  32  brings coolant from the heat exchanger  16  through the transport heating apparatus  20  and back to the heat exchanger  16 . Since the truck engine  12  is not being operated, there is no circulation of coolant from the engine  12  through the heat exchanger  16  and the circulator  32  creates a circuit that extends between the transport heating apparatus  20  and the heat exchanger  16 . 
         [0036]    As noted in step  43 , the delay timer  36  runs through its cycle while the circulator  32  moves coolant from the heat exchanger  16  through the transport heating apparatus  20 . Since there is no heat energy being supplied by the engine  12  to the heat exchanger  16 , the liquid material within the tanker trailer  15  acts as a heat sink that equalizes the temperature of the coolant within the heat exchanger  16  with the temperature of the liquid material within the tanker  15 . The operation of the delay timer  36  allows this coolant that was inside the tanker  15  to reach the transport heating apparatus  20 , as compared to the coolant that was within the coolant return conduit  19  which was exposed to the environment outside of the tanker trailer  15  and would, therefore, likely have a cooler temperature than the coolant from within the heat exchanger  16 , particularly if the ambient temperature is significantly cold. 
         [0037]    The length of the delay required by the delay timer  36  is programmable through dip switches  38  accessible at the top of the delay timer  36 . Preferably, the length of the delay is about a minute, but in practice depends on the circulation rate of the circulator  32  and the volume of coolant between the heat exchanger  16  and the transport heating apparatus  20 . The operation of the delay timer  36  is to allow sufficient time for coolant from within the heat exchanger  16  to reach the transport heating apparatus  20 . At step  44 , the delay timer  36  reaches the end of the delay cycle and activates the temperature switch  33  at step  45  to ascertain the temperature of the coolant that is now passing through the transport heating apparatus  20 . 
         [0038]    At step  46 , the temperature switch  33  compares the sensed temperature of the coolant with a present temperature parameter. If the sensed temperature is above the preset temperature parameter, then the cycle timer  35  turns off the circulator  32  at step  47  for a period of time determined by the settings of dip switches  39  accessible at the cycle timer  35  to adjust the timing of the cycle. The cycle timer  35  then cycles through the pre-established period of time at step  48  before starting the “on” sequence again at step  42 . The operation of the cycle timer  35  shuts down the circulator which has a substantial draw of electrical current from the battery  11 . Therefore, the cycle timer  35  saves electrical energy for use by the control mechanism  30  when the application of heat energy to the liquid material within the tanker  15  is required. 
         [0039]    The circulation of the coolant from the heat exchanger  16  into the transport heating apparatus  20  draws colder coolant from the coolant supply line  18  into the heat exchanger  16 . However, the heat sink that is the liquid material is sufficient to warm the new coolant to the same temperature as the liquid material within the tanker  15  during the period of time corresponding to the “off” sequence of the cycle timer  35 . Eventually, the period established by the cycle timer  35  expires and the cycle timer  35  goes into the “on” cycle at step  42  and once again activates the circulator  32  to bring coolant from the heat exchanger  16  into the transport heating apparatus  20 . The delay timer  36  allows the temperature switch  33  to delay sensing the temperature of the coolant when sufficient time has expired to allow the coolant from within the heat exchanger  16  to reach the temperature switch  33 . 
         [0040]    Again, the temperature switch  33  compares the sensed temperature with the preset temperature parameter at step  46  and moves the cycle timer  35  to the “off” sequence at step  47  if the sensed temperature is above the preset temperature parameter. The cycle continues through this testing loop  40  established by the cycle timer  35  until the temperature of the coolant passing through the temperature switch  33  drops below the preset temperature parameter at step  46  and the controls pass into the heating loop  50 . 
         [0041]    At step  51 , the delay timer  35  activates the operating relay  34  which assumes control of the power through the transport heating apparatus  20  and allows the cycle timer  35  to move into the “off” sequence at step  47 . At step  52 , the operating relay  34  and the temperature switch  33  activate the burner  25 , which then goes through the start cycle and fires heat energy into the boiler  28  at step  53 . Meanwhile, the circulator  32  continues to circulate coolant between the heat exchanger  16  and the transport heating apparatus  20 . The temperature switch  33  reads the temperature of the coolant coming into the transport heating apparatus  20  through the coolant supply line  29  at step  54  before being heated from the boiler  28  and decides at step  55  whether the temperature of the coolant, and therefore, the approximate temperature of the liquid material in the tanker  15  is above or below a pre-established temperature parameter, which is preferably at a higher level than the first temperature parameter used at step  46 , though could be the same temperature parameter. 
         [0042]    If the sensed temperature is above the preset temperature parameter, the temperature switch  33  turns off the operating relay  34  at step  56 , causing the burner  25  to go through its shut-down cycle and stop producing heat energy. On the other hand, if the sensed temperature is still lower than the preset temperature parameter at step  55 , the burner  25  is allowed to continue operating, transferring heat energy to the coolant in the boiler  28  which is circulated to the heat exchanger  16  to continue to warm the liquid material within the tanker trailer  15 . As long as the heating cycle  50  continues, the operation of the transport heating apparatus  20  is within the control of the relay  34 ; however, the cycle timer  35  continues to operate through its preset cycle. When the cycle timer  35  initiates the “on” sequence at step  42 , the circulator  32  is already operating and the relay  34  is already activated and the operation of the cycle timer  35  is of no consequence. Nevertheless, the cycle timer  35  continues through the testing loop  40  so long as electrical power is being supplied to the control mechanism  30  at step  41 . 
         [0043]    When the sensed temperature is greater than the preset temperature parameter at step  55  and the burner  25  shuts down, the control of the transport heating apparatus  20  is returned to the cycle timer  35  within the testing loop  40 . Assuming that the heating loop  50  shuts down when the cycle timer  35  is in mid-cycle, the “on” sequence at step  41  is undertaken in less time than a complete predetermined period for the cycle timer  35 , but the temperature of the coolant sensed at step  45  should substantially always be greater than the first preset temperature parameter and the cycle timer  35  will go through a complete cycle through the testing loop  40 . 
         [0044]    One skilled in the art will note that the transport heating apparatus  20  obtains fuel from the truck&#39;s fuel tanks  14  through the fuel line  26  and receives electrical power from the battery  11  carried by the truck  10  through the electrical connector  31 . Thus, the transport heating apparatus  20  is operable from the power and fuel supplies of the truck  10  even when the engine  12  of the truck  10  is shut down. Such an operation is beneficial in reducing vehicle emissions since the liquid material within the tanker trailer  15  can be kept at a desired temperature without requiring the engine  12  to be running. Furthermore, since the engine  12  is not running continuously to provide heat to maintain the temperature of the temperature-sensitive material, the desired temperature can be maintained with only about one-third of the fuel the truck  10  would have expended while continuously operating just to maintain the desired temperature. 
         [0045]    By turning on the power switch for the transport heating apparatus  20  while the truck  10  and tanker trailer  15  are moving along the highway, the transport heating apparatus  20  can be used to supplement the heat energy provided by the operation of the truck engine  12 . This supplemental operation of the transport heating apparatus  20  is particularly useful when temperature-sensitive food materials are being shipped by tanker truck  10  during really cold ambient temperatures. In such an operation, the engine heat is being transferred via normal operation of the coolant supply and return conduits  18 ,  19  interconnected the engine  12  and the heat exchanger  16 , but the engine cannot generate sufficient amounts of heat to keep the temperature-sensitive materials within the desired temperature range. 
         [0046]    Therefore, when the cycle timer  35  initiates the “on” sequence, as is noted above, at step  42 , the sensed temperature at step  45  of the coolant coming from the heat exchanger  16  through the return conduit  19  will be below the desired preset temperature as determined at step  46 . The relay  34  starts the circulator  32  running to draw the flow of coolant from the coolant return conduit  19  and returns the heated coolant back to the coolant supply conduit  18 , short-circuiting the primary heating loop between the heat exchanger  16  and the engine  12 . 
         [0047]    It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.