Patent Publication Number: US-9850873-B2

Title: Engine pre-heating system and method for multiple vehicles

Description:
TECHNICAL FIELD 
     Aspects of the present disclosure relate to climate controlled devices, and in particular, to an engine pre-heating system and method for multiple vehicles. 
     BACKGROUND 
     Engine heating elements, which are also referred to as block heaters, are devices used to pre heat engines in relatively cold climates when not in operation. In general, the engine heating elements replace core plugs (e.g., welch plugs, freeze plugs, engine block expansion plugs, etc.) of an engine and include a resistive element that generates heat when energized with electrical power. These engine heating elements are particularly useful in cold weather climates to maintain a minimum temperature level, thus alleviating detrimental effects, such as freezing of engine coolant of the engine that can permanently damage the engines, or increased difficulty of starting of the engine following a relatively long period of not being used. 
     SUMMARY 
     According to one embodiment of the present disclosure, an engine pre-heating system includes a housing that houses a climate control heating element and a controller configured in the housing. The controller generates an energizing signal for controlling an amount of electrical power provided to multiple engine heating elements that are thermally coupled to the engines of multiple vehicles. The controller also generates a climate control signal for controlling the climate controlled heating element to maintain the controller inside the housing within a specified temperature range. The energizing signal provided to the engine heating elements is inversely proportional to an ambient temperature proximate the engines. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features and advantages of the technology of the present disclosure will be apparent from the following description of particular embodiments of those technologies, as illustrated in the accompanying drawings. It should be noted that the drawings are not necessarily to scale; the emphasis instead is being placed on illustrating the principles of the technological concepts. Also, like reference characters may refer to the same components, features, and the like throughout the different views. The drawings depict only typical embodiments of the present disclosure and, therefore, are not to be considered limiting in scope. 
         FIG. 1  illustrates an example engine pre-heating system according to one embodiment of the present disclosure. 
         FIG. 2A  illustrates an example controller of the engine pre-heating system according to the teachings of the present disclosure. 
         FIG. 2B  illustrates an example thermostat of the engine pre-heating system according to the teachings of the present disclosure. 
         FIG. 3  illustrates an example process that may be performed by the system of  FIG. 1  to pre-heat multiple vehicle engines according to one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide an engine pre-heating system that includes a controller for simultaneously pre-heating the engines of multiple vehicles using a single climate controlled controller that adjusts the power provided to each engine according to a measured ambient temperature. While traditional engine pre-heating systems are mainly adapted for pre-heating of only one vehicle engine, the engine pre-heating system provides for the pre-heating of multiple vehicle engines in locations where climate control of its control system may not be inherently available, such as in a parking lot where multiple vehicles may be parked. Thus, whereas traditional engine pre-heating systems rely upon an existing climate controlled structure, such as a house, a commercial building, an inside compartment of the vehicle, or other form of housing structure to maintain the controller within acceptable operating temperatures, embodiments of the engine pre-heating system provides a climate controlled housing to ensure that proper operating temperature levels for the controller are adequately maintained. 
       FIG. 1  illustrates an example engine pre-heating system  100  according to one embodiment of the present disclosure. The engine pre-heating system  100  includes a housing  102  that houses a controller  104  that is coupled to, and receives a temperature signal from an ambient temperature sensor  106  external to the housing  102  for adjusting a level of electrical power provided from a power source  108  to multiple engine heating elements  110  configured on the engines  112  of multiple vehicles  114 . Further, the housing  102  also houses an internal heater  116  that is controlled by a thermostat  134  for maintaining a specified temperature level for the controller  104  disposed within the housing  102 . The housing  102  may also house a dehumidifier  118  to reduce humidity levels within the housing  102 . 
     In general, the system  100  includes a weather proof housing  102  with a controller  104  for preheating one or more vehicles (e.g., a fleet of vehicles) in inclement weather. The controller  104  is programmable an may incorporate desired temperature parameters for allowing or disallowing electrical power to engine heaters of each vehicle. The design of the programmed parameters is to provide a pulse width modulated (PWM) control over power provided to the engine heaters to allow for longer cycles when temperatures are low and shorter cycles when temperatures are relatively higher, thus saving energy and consumer costs. 
     The housing  102  may be mounted in any location where the engines  112  of multiple vehicles may be serviced using one or more electrical power distribution lines  122 . In the particular example shown, the housing is mounted proximate a parking lot  124  where the vehicles  114  are parked. Another example of a suitable location includes a construction site where multiple construction vehicles, such as dump trucks, backhoe devices, bulldozers, graders, and the like may be parked when not in use, such as overnight and after working hours. Another example includes a hotel or other commercial establishment having a parking lot where multiple patrons may park their vehicles during their overnight stay. Yet another example includes a parking lot for buses used by a public school system when not used for busing students to and/or from a school house. 
     In general, the housing  102  of the engine pre-heating system is placed at a suitable location where multiple vehicles may be situated. For example, the housing  102  may be mounted on a pole or placed on the ground proximate to a parking lot where multiple vehicles may be parked, while the electrical power distribution lines  122  have lengths sufficient to reach each vehicle without causing excessive power loss due to their inherent resistance. In a particular example in which electrical power provided to the engine heating elements  110  is a standard rated line power (e.g., 120 volts, 60 Hertz), the lengths of the electrical power distribution lines  122  may range from approximately 10 to 300 feet long to provide access the vehicle engines from the housing  102  without causing undue power loss due to excessive cabling length. Additionally, each electrical power distribution line  122  may be terminated with a connector  126  for ease of coupling and decoupling the engine heating elements  110  from the controller  104 . In the particular case in which the engine pre-heating elements use standard rated line power, each connector  126  may comprise a National Electrical Manufacturers Association (NEMA) 1-15 receptacle, a NEMA 5-15 receptacle, or other suitable connector. 
     In one embodiment, the system  100  may also include multiple receptacles (not shown) disposed proximate the housing  102  to couple the distribution lines  122  to the driver  128  in the housing  102 . In general, the multiple receptacles form an electrical plug-in station where users their own distribution line  122  to the system  100 . 
     The ambient temperature sensor  106  may be mounted in any suitable location having an ambient temperature level that approximates that of the engines  112  to be pre-heated. According to one embodiment, the ambient temperature sensor  106  is mounted outside of the housing  102  and at a distance and orientation away from the housing  102  such that the heat radiated from the climate controlled housing  102  does not adversely affect the ambient temperature around the ambient temperature sensor  106  to any substantial degree. For example, if the housing  102  is mounted on a pole, the ambient temperature sensor  106  may be mounted approximately 12.0 inches away from and below the housing  102  such that heat radiated by the housing  102  is mainly directed upward and away from ambient temperature sensor  106 . In this manner, the ambient temperature around the ambient temperature sensor  106  may accurately reflect the ambient temperature around the vehicle engines  112  to be pre-heated. Nevertheless, it should be understood that the ambient temperature sensor  106  may be mounted in any location having an ambient temperature approximating that of the vehicle engines to be pre-heated. 
     According to embodiments of the present disclosure, the engine pre-heating system  100  includes an internal heater  116  that is controlled by the controller  104  to maintain the space within the housing  102  at or above a specified temperature level, such as a minimum rated temperature level for the various components within the housing  102 . For example, a particular controller that incorporates a computer-based microprocessor that executes instructions stored in a memory, the microprocessor and/or memory components of the controller may typically have a minimum operating temperature of approximately 35.0 degrees Ferinheight. Nevertheless, overnight winter conditions in many northern regions can often go well below this level, thus inhibiting proper operation of the controller. Embodiments of the present disclosure provide a solution to this problem, among other problems, using the internal heater  116  that heats the components of the controller  104  to a safe operating temperature, thus enabling its operation in locations where existing climate controlled environments are not readily available, such as next to a parking lot where multiple vehicles may be parked for an extended period of time. 
     The thermostat  134  may selectively apply electrical energy to the internal heater  116 . In general, the thermostat  134  generates a climate control signal, which is used to control operation of the internal heater  116 , according to receipt of the ambient temperature measurement via the ambient temperature sensor  106  and/or an internal temperature measurement via an internal temperature sensor  132 . In one embodiment, the thermostat  134  generates the climate control signal according to receipt of the ambient temperature measurement via the ambient temperature sensor  106 . For example, the thermostat  134  may generate a pulse width modulated (PWM) signal that is inversely proportional to the ambient temperature signal to approximate an amount of energy to maintain the inside of the housing  102  above a specified temperature. 
     The climate control signal is used to modify an amount of electrical energy provided to the internal heater  116  to compensate for these measured temperatures. The thermostat  124  may modify the electrical energy delivered to the internal heater  116  based upon the measured ambient temperature using the ambient temperature sensor  106 , the internal temperature measurement acquired via the internal temperature sensor  132 , or a combination of both. 
     The power source  108  may be any source of electrical power used to power the controller  104 , internal heater  116 , dehumidifier  118 , and engine heating elements  110  configured on the vehicle engines  112 . In one embodiment, the power source  108  is the same type of rated electrical power used by the engine heating elements  110 . For example, if the engine heating elements  110  are rated for using the standard residential rated line power of 120.0 volts, 60.0 Hertz alternative current (AC), the power source  108  may be of that type. Conversely, if the engine heating elements  110  are rated for using 12.0 volts, direct current (DC) power, the power source  108  may be of that type. In another embodiment, the engine pre-heating system  100  includes a power converter (not shown) for converting the type of power provided by the power source  108  to that rated for use by the engine heating elements  110 . For example, if he engine heating elements  110  are rated for using standard rated line power (e.g., 120.0 volts, 60 Hertz AC) and the power source  108  is 380 volt, 3-phase AC power, the adapter may be included for converting the 380 volt, 3-phase power to 120 volt, single-phase power used by the engine heating elements  110 . 
     According to one embodiment, the engine pre-heating system  100  includes a dehumidifier  118  for reducing a level of humidity within the housing  102 . In general, the dehumidifier  118  comprises a relatively low level heating device that maintains the space within the housing  102  at an elevated temperature to ensure that condensate does not form inside. The dehumidifier  118  may be continuously powered, be cycled on and off at a specified duty cycle, and/or may be controlled by the controller  104  and/or the thermostat  134  to maintain a specified humidity level inside of the housing  102  using a humidity sensor configured inside the housing  102 . In a particular embodiment, the dehumidifier  118  comprises one marketed under the tradename GOLDENROD™, and manufactured by Battenfeld Technologies, Inc., which is headquartered in Columbia, Miss. 
     The housing  102  may be made of sheet metal, or other suitable material, which is formed into a shape, such as a box-like shape, to have a space that is accessible by a door for accessing the various components inside the housing  102 . In other embodiments, the housing  102  may have any suitable shape for housing the various components while providing climate control for the components configured inside. Additionally, the inside surface of the walls of the housing  102  may be lined with a thermal insulating material, such as foam or fiberglass, for enhancing the thermal resistance of the space within the housing  102  from the outside environment. 
     The system  100  also includes one or more electrical heating element drivers  128  that function under control of the controller  104  to selectively power the engine heating elements  110 . That is, the electrical heating element drivers  128  receive an energizing signal from the controller  104  and selectively apply electrical power from the power source  108  to the engine heating elements  110  according to the received energizing signal. For example, the electrical heating element drivers  128  may include one or more solid state relays that each uses a triode for alternating current (TRIAC) device for selectively applying electrical energy to the engine heating elements. Any number of electrical heating element drivers may be used that supplies ample current to power the desired number of electrical heating elements while remaining within their rated current capacity. 
     In one embodiment, the energizing signal comprises a pulse width modulating (PWM) signal having a duty cycle that increases as the ambient temperature decreases. In this case, the duty cycle represents an amount of time that the engine heating elements  110  are turned on (e.g., generating heat) relative to a second amount of time that the engine heating elements  110  are off (e.g., not generating any heat). For example, when the ambient temperature is measured to be 25 degrees Ferinheight, the controller  104  may generate the PWM signal having a 50 percent duty cycle (e.g., on for 30 minutes and off for 30 minutes), and when the ambient temperature is measured to be 12 degrees Ferinheight, the controller  104  may generate the PWM signal having a 75 percent duty cycle (e.g., on for 45 minutes and off for 15 minutes). The engine heating element drivers  128  may include any suitable type, such as one or more solid-state relays that switch on or off according to an input drive signal (e.g., the energizing signal). In one embodiment, the controller  104  can be programmed to accommodate varying climates. For example, the relative duty cycle may be increased for use in colder climates, such as Alaska, and be reduced for use in hotter regions, such as Texas. 
     The system also includes a delay timer  130  that measures the internal temperature of the housing  102  and withholds electrical power to the controller until the measured internal temperature is at a safe operating level for the other components (e.g., the controller  104 , the electrical heating element drivers, etc.) in the system  100 . For example, because it is not uncommon to experience extended power outages during severe inclement weather, such as a cold front in which temperatures may plummet to low levels, power to the system  100  may be lost for an extended duration such that the internal temperature of the housing goes below the safe operating temperature of its components. In such cases, the delay timer  130  functions to withhold the power from the controller and other components housed inside of the housing until safe operating temperatures are achieved. 
     The delay timer  130  may be any system that can selectively withhold electrical power to the internal heater  116  until a safe internal operating temperature is reached, and is capable of proper operation at any temperature that may be experienced inside the housing during an extended power outage. For example, the delay timer  130  may include components, such as one or more processors executing instructions stored in one or more memory units in which the processors and memory units are designed to function properly at relatively low temperatures. As another example, the delay timer  130  may include mechanical components that are designed to function properly at relatively low temperatures. 
     It should be appreciated that the components described in  FIG. 1  merely depict one particular example of the engine pre-heating system, and other embodiments may take other forms and/or have more or fewer components then those described herein without departing from the spirit or scope of the present disclosure. For example, one or more of the components of the system (e.g., the delay timer  130 ) may be configured outside of the housing  102  if climate control for these components is not needed or desired. Additionally, although the energizing signal used to drive the engine heating element drivers  128  is described above as a PWM signal, other embodiments contemplate that an analog energizing signal may be used to control operation thereof. As yet another example, the system  100  may include a communication circuit, such as a wireless transmitter and receiver, for receiving instructions for manipulating operation from a remote location, and transmitting telemetry data associated with its operation back to the remote location. 
       FIG. 2A  illustrates an example controller  104  of the engine pre-heating system  100  according to the teachings of the present disclosure. The controller  104  includes a general purpose computing device, such as a computer executing computer-executable instructions stored in a computer readable media  202 . The controller  104  includes a processing system  204  comprising one or more processors that execute a controller application  206  that is stored in the computer readable medium  202 . A processor is hardware. Examples of such a controller include a personal computer, a mobile computer, or a dedicated controller modules, such as a logic module marketed under the tradename LOGO™, which is available from Siemens Corporation with its headquarters in Munich, Germany. 
     The computer readable media  202 , which include both volatile and nonvolatile media, removable and non-removable media, can be any available medium that may be accessed by the general purpose computing device. By way of example and not limitation, computer readable media  202  may include computer storage media and communication media. Computer readable media  202  may further include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media may typically embody computer readable instructions, data structures, program modules, or other data in a modulated data signal, such as a carrier wave or other transport mechanism and include any information delivery media. Those skilled in the art will be familiar with the modulated data signal, which may have one or more of characteristics set or changed in such a manner that permits information to be encoded in the signal. The controller  104  may include or be capable of accessing computer storage media in the form of removable and/or non-removable, volatile and/or nonvolatile memory. 
     The controller  104  also includes a display  208 , such as a liquid crystal display, for displaying data, and an input device  210 , such as a keyboard or a pointing device (e.g., a mouse, trackball, pen, or touch screen) to enter data into or interact with the controller  104 . A user may enter commands and information into the controller  104  using an input device  210 . Other input devices, such as potentiometers or switches may also be connected to the controller  104 . The controller  104  may also operate in a networked environment using logical connections to one or more remote computers. 
     As shown, the application  206  includes several modules for performing the various features of the engine pre-heating system  100  described herein. 
     A user interface module  212  facilitates the receipt of input data and/or output data from or to a user, respectively. For example, the user interface module  212  may also display one or more selectable fields, editing screens, and the like for receiving the user configuration information from the user for manipulating operation of the application  206 . For another example, the user interface module  212  displays information associated with the operation of the application  206 , such as a current measured ambient temperature value and/or a duty cycle value determined by the application  206  at that ambient temperature. The user interface module  212  may also interface with one or more switches or other user input mechanisms, such as potentiometers having dials that may rotated or otherwise manipulated by the user for modifying operation of system  100 . 
     An energizing signal generating module  214  generates an energizing signal in accordance with a measured ambient temperature associated with the vehicle engines  112 . In one embodiment, the energizing signal generating module  214  generates an energizing signal that is inversely proportional to the measure ambient temperature value. For example, the energizing signal generating module  214  may generate a PWM signal having a duty cycle that increases when the ambient temperature decreases. As another example, the energizing signal may be an analog signal representing a proportional level of electrical power from the power source  108  to be applied to the engine heating elements  110 . 
     An engine pre-heat recording module  216  maintains an ongoing record of cumulative electrical energy consumed by the system  100  and provides this information to the user upon demand. For example, the engine pre-heat recording module  216  displays the result in response to a request from a user via the user interface module  212 . As another example, the engine pre-heat recording module  216  stores the cumulative electrical energy consumed by the system  100  in a removable storage media, such as a universal serial bus (USB) stick memory, that may be temporarily removed and plugged into another computing device to access the information. For embodiments using a PWM energizing signal, the engine pre-heat recording module  216  maintains a resettable time counter that is incremented as long as the engine heating elements  110  are energized such that the cumulative energy consumed by the system  100  over a specified period of time may be calculated. In some embodiments, the engine pre-heat recording module  216  may also record power measurements received from a watt meter to automatically calculate the cumulative energy used by the system  100  over the specified period of time. 
     A system override management module  220  continually monitors the user interface module  212  for the presence of an override setting and overrides the controller to continually apply electrical power to the electrical distribution cables  122  when the override setting is set (e.g., active). In one embodiment, the system override management module  220  receives the override setting from a hardware switch (e.g., single pole, single throw switch) configured inside of the housing  102 . In other embodiments, the system override management module  220  receives the override setting from any suitable input, such as via the user interface  212  of the controller. Embodiments of the override setting may be useful in cases where no extreme whether condition exists (e.g., extreme cold conditions) so that the electrical distribution cables  122  may be used for other purposes, such as powering one or more power tools around the parking lot where the vehicles may be otherwise parked. 
     It should be appreciated that the modules described herein is provided only as examples that perform the various features of the vehicle pre-heating system, and that other computing systems may have the same modules, different modules, additional modules, or fewer modules than those described herein. For example, one or more modules as described in  FIG. 2A  are combined into a single module. As another example, certain modules described herein are encoded on, and executed on one or more other computing systems. 
       FIG. 2B  depicts an example thermostat  134  according to the teachings of the present disclosure. The example thermostat as shown incorporates a computing device having a memory  232  for storing a temperature control application  234  that may be executed by one or more processors  236 . 
     The computing device may be any suitable type. For example, the computing device can be a personal computer, such as a laptop or notebook computer, a workstation, or other processing device such as a personal digital assistant or a tablet computer. In a particular embodiment, the computing device include a single-chip controller device having one or more inputs for receiving an internal temperature signal from the internal temperature sensor  132  and one or more outputs for controlling operation of the internal heater  116 . 
     The temperature control application  234  generates a climate control signal for energizing the internal heater  116  to maintain the inside of the housing  102  at or above a specified temperature level. The specified temperature level may include any level in which the various components within the housing  102  may be safely operated at. For example, if the components (e.g., controller  104  and electrical heating element drivers  128 , etc.) have a minimum safe operating temperature of 35 degrees Ferinheight, the specified temperature may be set at 45 degrees Ferinheight to ensure that the minimum temperature level is maintained so that the components may be free from damage. 
     Although the particular example thermostat shown incorporates a computing device that executes a temperature control application  234  using a processor, it should be appreciated that the thermostat may be embodied in other specific forms without deviating from the spirit and scope of the present disclosure. For example, the thermostat  1 xx may include a mechanical relay that opens as the sensed temperature increases and closes as the sensed temperature decreases. Additionally, the thermostat may be integrated in the controller  104  as shown in FIG.  1 B such that the temperature control application  234  is stored in the computer readable media  202  and executed by the processing system  204  of  FIG. 2A . 
       FIG. 3  illustrates an example process that may be performed by the system of  FIG. 1  to pre-heat multiple vehicle engines  112  according to one embodiment of the present disclosure. 
     In step  302 , the system  100  electrical power distribution lines  122  are electrically coupled to the engine heating elements of multiple vehicle engines. To this end, the housing  102  with its associated components are placed in a location, such as a parking lot, where the vehicles may be accessed by the electrical power distribution lines  122 . Thereafter, electrical power is applied to the system in step  304 . That is, the power source  108  is electrically coupled to the delay timer  130 . 
     In step  306 , receives an internal temperature measurement of the temperature inside the housing to determine whether the internal temperature is at or above a minimum operating temperature for the components in the housing. If not, the delay timer  130  applies electrical power (step  308 ) to the internal heater  116  and continues at step  306  until the minimum rated operating temperature is reached. 
     In another embodiment, the delay timer  130  may wait for a specified period of time without regard for any internal temperature measurement of the temperature inside of the housing. For example, when initially turned on, the delay timer  130  may withhold electrical power to the controller and/or thermostat until a specified period of time, such as 1 hour, has elapsed. Additionally, the specified period of time may be manually set by a user to be greater than 1 hour or less than 1 hour. 
     Such functionality may be particularly useful for scenarios in which the power source  108  fails (loss of line power) for an extended period of time in extremely cold weather. However, when the minimum rated operation temperature is reached, processing continues at step  310  in which electrical power is applied to the controller  104  that assumes control over the operation of the system  100 . 
     In step  312 , the controller  104  and thermostat  132  are initialized. For example, initialization of the controller and/or thermostat may generally involve a process in which the controller  104  executes a sequence of executable instructions for booting its registers and other stateful components, loading the application  206  into the computer readable media  202 , and initializing its execution. 
     In step  314 , the application  206  receives a temperature measurement from the ambient temperature sensor  106 , and generates an energizing signal in response to the received ambient temperature measurement in step  316 . In one embodiment, the energizing signal comprises a PWM signal having a duty cycle that is inversely proportional to the measured ambient temperature. That is, the application  206  generates the PWM signal such that the amount of time that the engine heating elements are energized increases as the temperature decreases and vice-versa. 
     In step  318 , the application  206  adjusts the relative level of energy provided to the engine heating elements  110  according to manual intervention provided by the user. For example, the application  206  may adjust the duty cycle of the PWM signal according to manual input received via the input device  210 . The input device  210  may include any suitable mechanism for entry of a relative energy level adjustment, such as via a graphical user interface of the controller  104 . In one embodiment, the input device  210  includes a potentiometer that is configured in a voltage divider circuit to generate an analog voltage that may be read by the application  206  to adjust the relative level of energy provided to the engine heating elements  110 . 
     In step  320 , the thermostat  134  adjusts a level of electrical energy provided to the internal heater  116  to maintain the components inside the housing  102  at or above a specified minimum rated operating temperature. In one embodiment, the thermostat  134  adjusts the level of electrical energy according. to ambient temperature measurements received from the ambient temperature sensor  106 . For example, the thermostat  134  may use the ambient temperature measurement obtained from the ambient temperature sensor  106  for estimating a level of electrical energy to be provided to the internal heater to maintain the internal temperature of the housing above the specified temperature level. 
     In another embodiment, the thermostat  134  adjusts the level of electrical energy according to internal temperature measurements received from an internal temperature sensor  132  configured inside the housing  102 . That is, whereas the thermostat  134  may use the ambient temperature sensor  106  to estimate a level of energy to be provided to the internal heater  116 , the internal temperature sensor  132  may be used to form a closed-loop feedback system for controlling the temperature within the housing  102 . 
     Certain embodiments incorporating the use of the ambient temperature sensor  106  for estimating a level of internal heating may provide advantages of reduced costs and lower complexity due to not requiring the internal temperature sensor  132 , while other embodiments incorporating the internal temperature sensor  132  may provide other advantages of enhanced control over the internal temperature using a closed-loop feedback system. 
     In step  322 , the application  206  determines whether a manual override signal has been received. Is so, processing continues at step  324  in which the application  206  generates the energizing signal such that the electrical cables are continuously on. Such a case may be useful in scenarios in which the electrical cables may be used for powering other devices, such as battery chargers, power tools, or other devices requiring the use of electrical power proximate the location where the housing  102  is positioned. 
     However, if the application  206  determines that the manual override signal is not received in step  322 , processing continues at step  314  where control over the heating elements  110  of the vehicle engines, and the internal space within the housing  102  are maintained. 
     The previously described process continues throughout operation of the engine pre-heating system. Nevertheless, when use of the engine pre-heating system is no longer needed or desired, the process ends. 
     Although  FIG. 3  describes one example of a process that may be performed by the system  100  for simultaneous pre-heating of multiple vehicles, the features of the disclosed process may be embodied in other specific forms without deviating from the spirit and scope of the present disclosure. For example, the system  100  may perform additional, fewer, or different operations than those operations as described in the present example. As another example, the steps of the process described herein may be performed by a computing system other than the controller  102 , which may be, for example, the delay timer  130  configured inside of the housing  102 . 
     Embodiments of the present disclosure include various operations or steps, which are described in this specification. The steps may be performed by hardware components or may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor programmed with the instructions to perform the steps. Alternatively, the steps may be performed by a combination of hardware, software and/or firmware. 
     It is believed that the present disclosure and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction, and arrangement of the components without departing from the disclosed subject matter or without sacrificing all of its material advantages. The form described is merely explanatory, and it is the intention of the following claims to encompass and include such changes. 
     While the present disclosure has been described with reference to various embodiments, it will be understood that these embodiments are illustrative and that the scope of the disclosure is not limited to them. Many variations, modifications, additions, and improvements are possible. More generally, embodiments in accordance with the present disclosure have been described in the context of particular implementations. Functionality may be separated or combined in blocks differently in various embodiments of the disclosure or described with different terminology. These and other variations, modifications, additions, and improvements may fall within the scope of the disclosure as defined in the claims that follow.