The present invention generally relates to a vehicle radiant heating control system. More specifically, the present invention relates to supplying heat to a vehicle cabin interior space using a radiant heating element in a vehicle having a 12VDC battery.
For many years, automotive vehicles have been provided with climate control systems (e.g., heating, ventilating and air conditioning (HVAC) systems) in order to provide a more comfortable environment for the driver and any passengers. Passenger compartments of vehicles have traditionally been warmed by circulating air such that it contacts a heater core associated with a coolant loop of an internal combustion engine. Thus, the heater core is normally heated by the engine coolant from the vehicle's engine. In cold conditions, when the vehicle is first started, the engine is cold. Thus, the engine coolant is also cold and is insufficient to warm the air entering the vehicle cabin. This results in a period of time in which the cabin remains below the desired cabin temperature.
In recent years, hybrid vehicles and electric vehicles have become more popular. Given the vehicle market trend toward hybrid vehicles and electric vehicles, new ways to generate cabin heat for occupants are being explored. As mentioned above, passenger compartments of vehicles have traditionally been warmed by circulating air such that it contacts a heater core. However, such a heater core would not be present in an electric vehicle. Also, even in the case of an internal combustion engine of a hybrid vehicle, it can often take a long time for a heater core to warm up on a very cold day. Thermally radiant electrical devices are often used as heating elements (e.g., heat lamps to keep food warm) and have been proposed for use in vehicles. For example, use of an infrared heater has been proposed in U.S. Pat. No. 3,619,555 to Bassett, Jr. (assigned to General Motors Corporation). However, it has been discovered that radiant heating elements are typically high-wattage devices powered by AC mains, which makes them less feasible for use in vehicles since vehicle electronics are usually powered by a 12 volt DC battery or other direct current battery source.
In view of the state of the known technology, one object of the present invention is to provide a vehicle radiant heating control system that is well suited for vehicles having a direct current battery source.
In accordance with one aspect of the present invention, a vehicle radiant heating control system is provided that comprises a radiant heating element, a power source and a controller. The power source is operatively connected to the radiant heating element. The controller operatively controls the radiant heating element and the power source. The controller operates the radiant heating element by intermittently supplying power generated by the power source to the radiant heating element.
Referring now to the attached drawings which form a part of this original disclosure:
Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
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With the arrangement of this illustrated embodiment, the radiant heating elements 20 and 22 of the vehicle radiant heating control system 14 can use off-the-shelf bulbs (e.g., commercial 250 watt and 500 watt infrared bulbs). Thus, the vehicle radiant heating control system 14 of the illustrated embodiment significantly reduces costs in comparison to those systems requiring specialized heating elements in that the vehicle radiant heating control system 14 of the illustrated embodiment is capable of utilizing off-the-shelf bulbs.
In this illustrated embodiment, the vehicle radiant heating control system 14 is activated by turning on a vehicle ignition 32 and deactivated by turning off the vehicle ignition 32. In addition to the vehicle ignition 32, the user interface 18 can be provided with an on/off switch for activating and deactivating the vehicle radiant heating control system 14. Thus, the vehicle ignition 32 is operatively connected to the HVAC controller 16, such that the vehicle ignition 32 enables operation of the HVAC controller 16 when the vehicle ignition 32 is turned on.
The HVAC controller 16 preferably includes a microcomputer with an HVAC control program that controls heating of the vehicle cabin interior space 12. Preferably, the HVAC controller 16 sets a target surface temperature or temperatures, depending on the heating mode, and controls the lower and upper radiant heating elements 20 and 22 towards the target surface temperature(s) based on an effective or estimated surface temperature directly in front of the upper infrared heater(s) in the vehicle cabin interior space 12, as discussed below. The HVAC controller 16 can also include other conventional components such as an input interface circuit, an output interface circuit, and storage devices such as a ROM (Read Only Memory) device and a RAM (Random Access Memory) device. The microcomputer of the HVAC controller 16 is programmed to control at least operation of the radiant heating elements 20 and 22. Basically, the HVAC controller 16 controls the radiant heating elements 20 and 22 so as to automatically maintain an interior surface temperature of the vehicle cabin interior space 12 to a user target temperature. In other words, sensors monitor the temperatures of the vehicle's interior to determine if the user target surfaces have been reached. The HVAC controller 16 processes this information and compares it with the target temperature.
The user interface 18 is operatively connected to the HVAC controller 16, with the HVAC controller 16 activating the radiant heating elements 20 and 22 via the user interface 18. The user interface 18 is also configured to allow a user to set a target cabin interior temperature for the vehicle cabin interior space 12 as well as other settings such as selecting a heating mode. These settings are carried out by the HVAC controller 16, which is operatively coupled to the components of the vehicle radiant heating control system 14 to selectively operate the radiant heating elements 20 and/or 22 to heat the vehicle cabin interior space 12. Basically, in the vehicle radiant heating control system 14, the HVAC controller 16 is operatively coupled to the lower and upper radiant heating elements 20 and 22 to selectively operate the lower and upper radiant heating elements 20 and 22 at prescribed conditions, especially when the temperature directly in front of the lower radiant heating elements 20 drops below a prescribed temperature range as described below. In particular, the operation times of the radiant heating elements 20 and 22 are controlled by achievement of a target surface temperature rather than cabin interior air temperature.
Preferably, the user interface 18 allows the user to set to various heating modes. In other words, the user interface 18 includes a mode input switch in which the user can select a floor heat mode (e.g., operation of only the lower radiant heating elements 20), a defog or defrost mode (e.g., operation of only the upper radiant heating elements 22), or a full heat mode (e.g., both the lower and upper radiant heating elements 20 and 22). During each of these modes, the blower B can be either automatically or manually operated so that the blower B can be turned “on”, set to a preferred blower speed and turned “off” as needed and/or desired. For example, in the case of the defog or defrost mode, the blower B can be automatically turned “on” and adjusted to a preset speed when the defog or defrost mode is selected. In this automatic defog or defrost mode, the user interface 18 can be set to a plurality of defog or defrost settings with the target surface temperature of the upper radiant heating elements 22 and/or blower speed changing with each setting. Alternatively, in the case of the defog or defrost mode, the blower B can be manually operated and set to one of a plurality of preset speeds when the defog or defrost mode is selected.
The lower and upper radiant heating elements 20 and 22 can be any of a variety of different types and styles of infrared elements that produce only infrared waves. Although some infrared elements are designed to produce a certain type of visible light wave or other types of waves for specific purposes (for example, to indicate when the element is being powered), most infrared elements for use in the vehicle infrared heating control system 14 substantially produce only infrared waves. Assorted AC radiant heating elements are commercially available. However, infrared heat lamps in the non-visible range, particularly carbon, are especially suitable for the lower and upper radiant heating elements 20 and 22. Preferably, the lower and upper radiant heating elements 20 and 22 emit either IR-B waves or IR-C waves. The IR-B wavelength range is preferably 2000 to 3500 nm. While the IR-C wavelength range is preferably greater than 3500 nm. The lower and upper radiant heating elements 20 and 22 can be operated with about 150 to 250 watts of input power.
Long Waves (IR-C waves with wavelengths longer than 2000 nm) are also effective for heat integration while at the same time being substantially incapable of detection by vehicle occupants. For this reason, the lower radiant heating elements 20 are preferably IR-C type infrared elements. However, with respect to the upper radiant heating elements 22, water molecules typically do not absorb IR-C waves. Thus, window defogging performance may suffer somewhat if IR-C type infrared elements are selected for the upper radiant heating elements 22 over IR-B type infrared elements. For this reason, the upper radiant heating elements 22 are preferably IR-B type infrared elements.
As mentioned above, the lower radiant heating elements 20 are arranged in the dashboard 24 so that the lower radiant heating elements 20 are aimed into the foot-wells to supply heat to the foot-wells of the vehicle cabin interior space 12. Each of the lower radiant heating elements 20 has a temperature sensor 34 that is mounted to a grill or lens of the dashboard 24 in front of the lower radiant heating elements 20. The temperature sensors 34 are operatively connected to the HVAC controller 16, with the temperature sensors 34 detecting the temperatures of the lower radiant heating elements 20. The sensors 34 are also used to limit the temperature of the grill or lens surface that is heated and that vehicle occupants may potentially contact. The sensor's temperature (after mathematical adjustment based on heat transfer properties) is used to control the temperature of a target surface within the cabin (passenger feet, windshield, etc.). Alternatively, one of the temperature sensors 34 alone may be used to regulate operation of both of the lower radiant heating elements 20. However, if both of the temperature sensors 34 are used with the lower radiant heating elements 20, then the vehicle radiant heating control system 14 can independently adjust the heat output to the driver's side of the vehicle cabin with respect to the passenger's side of the vehicle cabin. In this way, the user interface 18 can independently set target surface temperatures for the driver's side of the vehicle cabin and the passenger's side of the vehicle cabin.
In the illustrated embodiment, a passenger presence sensor 38 is provided in the passenger's seat to determine whether a passenger is present in a front passenger seat of the vehicle cabin interior space 12. The passenger presence sensor 38 is operatively connected to the HVAC controller 16 for operation by the HVAC controller 16, with the passenger presence sensor 38 detecting an occupancy status of a passenger seat and sending a signal to the HVAC controller 16 to indicate when the seat is occupied or vacant. Using this passenger presence sensor 38, the controller 16 can automatically perform a stopping operation of the lower infrared heater 20 that is located on the passenger's side of the vehicle cabin based on a detection result of the passenger presence sensor 38 indicating that the front passenger seat of the vehicle cabin interior space 12 is empty. In other words, the HVAC controller 16 suspends operation of the lower radiant heating element 20 on the passenger's side when the passenger presence sensor 38 detects an occupancy status indicative of the passenger seat being vacant. The passenger presence sensor 38 can be of the same type that is also used for “enabling” or “disabling” the passenger's air bag(s) function.
As mentioned above, the upper radiant heating elements 22 are arranged in the A-pillars 28 adjacent the dashboard 26 to apply heat across an interior surface of the dashboard 26 and to supply heat to an upper area of the vehicle cabin interior space 12. Each of the upper radiant heating elements 22 has a temperature sensor 36 that is mounted to a grill or lens in front of the upper radiant heating elements 22. The temperature sensors 36 are operatively connected to the HVAC controller 16, with the temperature sensors 36 detecting the temperatures of the radiant heating elements 22. Alternatively, one of the temperature sensors 36 alone may be used with the upper radiant heating elements 22, or the temperature sensors 36 may be omitted completely from the vehicle radiant heating control system 14. If neither of the temperature sensors 36 are used with the upper radiant heating elements 22, then the temperature sensors 34 of the lower radiant heating elements 20 can be used to control the operation of the upper radiant heating elements 22.
The HVAC controller 16 intermittently supplies power to the radiant heating elements 20 and/or 22 based on the temperature(s) of the radiant heating elements 20 and/or 22 such that the HVAC controller intermittently 16 supplies power to the radiant heating elements 20 and/or 22 for a predetermined time period in the 8.33 msec range when the temperature(s) of the radiant heating elements 20 and/or 22 are below a proportional temperature T1 such as 30 degrees Celsius. The HVAC controller 16 further interrupts the supply of power to the radiant heating elements 20 and/or 22 following the predetermined proportional time period allowing the radiant heating elements 20 and/or 22 to charge for the next period.
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The power converter 40 increases an electric potential of the power generated by the battery 30 (i.e., the power source). For example, the power converter 40 steps up the 12-volt direct current from the battery 30 to a higher DC voltage such as 100 volts. This stepped up voltage is used to charge the power storage device 42, which can be a conventional capacitor or other suitable storage device. The power from the power storage device 42 is then delivered by the power switch 44 (e.g., the delivery system) as a DC pulse voltage to the radiant heating elements 20 and/or 22 for producing heat to heat the vehicle cabin interior space 12. The power storage device 42 discharges when the HVAC controller 16 supplies power to the radiant heating elements 20 and/22. The HVAC controller 16 then charges the power storage device 42 while the HVAC controller 16 interrupts the supply of power to the radiant heating elements 20 and/or 22 by controlling the power switch 44 using the power switch control 46. The HVAC controller 16 interrupts the supply of power to the radiant heating elements 20 and/or 22 by changing an operating state of the power switch 44.
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In this illustrated embodiment, a commercial 500 watt infrared bulb, which is designed for AC operation using 120VAC, can be used in the radiant heating elements 20 and 22 for producing 150 to 250 watts. Thus, the bulbs designed for AC operation using 120VAC are preferably used in the radiant heating elements 20 and 22 in order to lower the overall cost of the vehicle radiant heating control system 14. By applying a 100VDC pulse of varying width, it is possible to cause the bulbs of the radiant heating elements 20 and 22 to radiate at a lower power so that a commercial 500 watt infrared bulb can produce 150 to 250 watts from the bulbs of the radiant heating elements 20 and 22.
In this illustrated embodiment, the radiant heating control system 14 uses the R factor in an RC circuit to discharge the power storage device 42 (e.g., a conventional capacitor) that is holding the energy to cause the bulbs of the radiant heating elements 20 and 22 to radiate. The power switch 44 (delivery system) constitutes a discharge controlling device for connecting the power storage device 42 (e.g., capacitive storage device) to the bulbs of the radiant heating elements 20 and 22 and for allowing the energy to discharge. In the illustrated embodiment, for example, the power switch 44 (delivery system) can be a low resistance energy field effect transistor (FET). While discharging, the voltage to the power storage device 42 (e.g., a conventional capacitor) continues but is unidirectional. While the bulbs of the radiant heating elements 20 and 22 are in an off state the power storage device 42 (e.g., capacitive storage device) is being charged for the next pulse. This allows for the use of off-the-shelf, commercially available infrared bulbs (e.g., 500 watt) as radiant heating elements in a vehicle having a 12 volt DC battery or other suitable direct current power source.
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In step S1, the controller 16 determines if the power storage device 42 is charged to a level designed to deliver a pulse of energy forcing the radiant heating elements 20 and/or 22 to emit infrared waves. If the power storage device 42 is charged to the prescribed level, then the process executed by the controller 16 proceeds to step S2. However, if the power storage device 42 has not reached the prescribed level, then the process executed by the controller 16 repeats step S1 until the power storage device 42 has reached the prescribed level.
In step S2, the controller 16 sends a signal to close the power switch 44, and then subsequently after a time period has elapsed, the controller 16 sends a signal to open the power switch 44. Next, the process executed by the controller 16 proceeds to step S3.
In step S3, the controller 16 receives signals from the temperature sensors 34 and/or 36 depending on the operation mode to determine a measured temperature Tm, which is indicative of actual temperatures in front of the radiant heating elements 20 and/or 22, and then proceeds to step S4.
In step S4, the controller 16 compares the measured temperature Tm with a prescribed temperature value T1. If the measured temperature Tm is less than the prescribed temperature value T1, then the process executed by the controller 16 proceeds to step S5. However, if the measured temperature Tm is greater than the prescribed temperature value T1, then the process executed by the controller 16 repeats steps S3 and S4 until the measured temperature Tm is less than the prescribed temperature value T1.
In step S5, the controller 16 determines whether the radiant heating elements 20 and/or 22 are currently activated or not. If the radiant heating elements 20 and/or 22 are currently inactivated, then the process executed by the controller 16 ends. However, if the radiant heating elements 20 and/or 22 are currently activated, then the process executed by the controller 16 proceeds back to step S2 so as to continuously repeat steps S2 to S5, until the radiant heating elements 20 and/or 22 are inactivated or the vehicle 10 is turned off.
Thus, the method for operating the vehicle radiant heating control system 14 is basically performed by the HVAC controller 16 supplying power generated by the power source (e.g., the battery 30) to the radiant heating elements 20 and/or 22 for a predetermined time period. Then, the controller 16 interrupts the supplying of power to the radiant heating elements 20 and/or 22 upon expiration of the predetermined time period. Next, the controller 16 detects a temperature of the radiant heating elements 20 and/or 22 after the interrupting of the supplying of power. Finally, the controller 16 subsequently resupplies power to the radiant heating elements 20 and/or 22 in response to the temperature of the radiant heating elements 20 and/or 22 being detected as being below a predetermined temperature from the detecting of the temperature of the radiant heating elements 20 and/or 22.
While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
This application is a related application of U.S. patent application Ser. No. 12/359,804, filed on Jan. 26, 2009. The entire disclosure of U.S. patent application Ser. No. 12/359,804 is hereby incorporated herein by reference.