Abstract:
Vehicles and methods for controlling climate control systems may include, but are not limited to at least one seat, a climate control system, and a controller communicatively coupled to the climate control system, wherein the controller is configured to calculate a directional sun effect for each of the at least one seats, and modify at least one of an airflow, a temperature and air distribution of the climate control system based upon the calculated directional sun effect for each of the at least one seats.

Description:
TECHNICAL FIELD 
     The technical field generally relates to climate control systems, and more particularly relates to automatic climate control systems which compensate for solar exposure. 
     BACKGROUND 
     Automatic climate control systems are becoming more prevalent in vehicles. Such systems attempt to regulate the temperature inside the vehicle to a temperature set by the user. Generally these climate control systems determine a temperature and an airflow required to regulate the temperature based upon a lookup table which has to be tuned based upon iterative vehicle tests. The tuning can be subjective and may not accurately control the temperature. 
     SUMMARY 
     In one embodiment, for example, a vehicle is provided. The vehicle may include, but is not limited to at least one seat, a climate control system, and a controller communicatively coupled to the climate control system, wherein the controller is configured to, calculate a directional sun effect for each of the at least one seats, and modify at least one of an airflow, a temperature and an air distribution of the climate control system based upon the calculated directional sun effect for each of the at least one seats. 
     In another embodiment, for example, a method for controlling an automatic climate control system in a vehicle comprising at least one seat is provided. The method may include, but is not limited to calculating, by a processor, a directional sun effect for each of the at least one seats, and modifying, by the processor, at least one of an airflow, a temperature and an air distribution output by the automatic climate control system based upon the calculated directional sun effect for each of the at least one seats. 
     In yet another embodiment, for example, a climate control system is provided. The climate control system may include, but is not limited to a heating system, an air conditioning system, and a controller communicatively coupled to the climate control system, wherein the controller is configured to calculate a directional sun effect for at least one seat, and modify at least one of an airflow, a temperature and an air distribution output from one of the heating system and the air conditioning system based upon the calculated directional sun effect for each of the at least one seats. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The exemplary embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is a block diagram of an exemplary vehicle, in accordance with an embodiment; 
         FIG. 2  is a partial perspective view of a vehicle, in accordance with an embodiment; 
         FIG. 3  is a partial perspective view of an interior of a vehicle, in accordance with an embodiment; 
         FIG. 4  is a flow chart illustrating a method for controlling a climate control system, in accordance with an embodiment; 
         FIGS. 5-8  illustrate the calculations involved in determining an area of a seat exposed to solar rays, in accordance with an embodiment; 
         FIG. 9  illustrates an exemplary air flow, temperature and air distribution, in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     As discussed above, conventional automatic climate control systems are tuned based upon iterative subjective tests. Accordingly, conventional automatic climate control systems do not accurately compensate for the actual solar load on the occupants of the vehicle. In other words, the occupant of the vehicle, when the sun is directly shining on the occupant, may not experience a set temperature because the conventional system does not accurately take into account where the sun is shining through various windows of the vehicle and how that may affect the temperature experienced by the occupant. Accordingly, as discussed in further detail below, a vehicle is provided with a climate control system which calculates the actual solar load on the interior of the vehicle and modifies the temperature, airflow and air distribution output by the climate control system to compensate for the solar load in the vehicle. 
       FIG. 1  is a block diagram of an exemplary vehicle  100 , in accordance with an embodiment. The vehicle  100  may be an automobile, an aircraft, a spacecraft, a watercraft or any other type of vehicle that utilizes heating and/or cooling systems. The vehicle includes a climate control system  110 . The climate control system  110  includes an air conditioning system  120  to provide cooled air to the interior of the vehicle  100  and a heating system  130  to provide warmed air to the interior of the vehicle  100 . The air conditioning system  120  and heating system  130  of the climate control system  110  may include, but are not limited to, at least one air delivery motor, at least one blower motor, at least one heat exchanger, a compressor, at least one thermal expansion valve, and at least one coolant pump, and a variety of piping and exhaust vents to provide cooled air to the interior of the vehicle  100 . 
     The climate control system  110  further includes a controller  140  for controlling the climate control system  110 , as discussed in further detail below. The controller  140  may include a microprocessor, a microcontroller, an application specific integrated circuit, a field programmable gate array, a physics processing unit, a graphics processing unit, or any other type of logic device or combination thereof. The controller  140  may be shared by other systems in the vehicle  100  or may be specific to the climate control system  110 . 
     The controller  140  receives input from a user interface  150 . The user interface  150  may be mounted on a dashboard of the motor vehicle (not illustrated) or provided on the smart phones or the other smart devices of a user (not illustrated) and provide a user with controls for the climate control system  110 . In one embodiment, for example, the climate control system  110  may be an automatic climate control system where a user sets a temperature for the vehicle  100  via the user interface  150  and the controller  140  controls the climate control system  110  to maintain the selected temperature. The user interface  150 , for example, may allow a user to set a different temperature for different zones of the vehicle. Some climate control systems  110 , for example, may allow for different temperature settings between a driver and a passenger. In other embodiments, for example, the climate control systems  110  may also have a different zone for the left side of the vehicle, the right side of the vehicle, each individual row of the vehicle or any combination thereof. 
     The controller  140  may receive input from a single-cell solar sensor  160  otherwise known as a single zone solar sensor. The single-cell solar sensor  160  includes one photo-diode which outputs a voltage corresponding to an intensity of solar rays from the sun hitting the single-cell solar sensor  160 . In one embodiment, for example, the voltage output from the single-cell solar sensor  160  may correspond to the solar intensity in units of watts per square meter. Sensor voltage is compensated when the solar sensor is not directly exposed to solar rays by the cumulative moving average of the sampled sensor data for a predefined period of time. Cumulative moving average of the solar sensor voltage is eventually equal to the current sensor voltage, when the solar sensor is not directly exposed to solar rays for an extended period of time. 
     In another embodiment, for example, the controller  140  may receive input from a multi-cell solar sensor  170 , otherwise known as a multi-zone solar sensor. The multi-cell solar sensor  170  includes multiple photo-diodes, each outputting a voltage corresponding to an intensity of solar rays from the sun hitting the respective photo-diode in the multi-cell solar sensor  170 . A comparison between the output of the each photo-diode can be used to determine a solar elevation (otherwise known as zenith) and an azimuth angle. 
     The controller  140  further receives input from a global positioning system (GPS) receiver  180 . GPS is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. The GPS receiver  180 , based upon the signals from the GPS satellites, can calculate an accurate location of the vehicle. Using the location of a vehicle, vehicle driving direction information, and the time information, sun elevation angle and sun azimuth angle can be determined. 
     The controller  140  may further receive input from a memory  190 . The memory  190  may be any non-volatile memory, including, but not limited to, a hard disk drive, flash memory, read only memory, or optical drive. In one embodiment, for example, the memory  190  may be a cloud based memory remote from the vehicle and accessed by a communication system (not illustrated). The memory  190  stores vehicle geometry data. The vehicle geometry data includes the dimensions and relative position of the windshield of the vehicle, the side windows, the rear window, sunroof, convertible roof, the seats of the vehicle, and the solar sensor, either single-zone solar sensor  160  or multi-zone solar sensor  170 . In addition, the vehicle seats can be movable, and the vehicle seats may have variable multi-dimensional coordinate points. In one embodiment, for example, the vehicle geometry data may be measured and stored in the memory  190  in advance, such as at the factory. 
     As discussed in further detail below, the controller  140 , based upon the data from one or more of the user interface  150 , the single-cell solar sensor  160  and the GPS receiver  180  or the multi-cell solar sensor  170 , and the memory  190 , determines which seats of the vehicle  100  are directly exposed to solar rays and calculates the solar load on the interior of the vehicle, to control the temperature, airflow and air distribution output from the climate control system  110  to maintain the selected temperature which is determined based upon the user input. 
       FIG. 2  is a partial perspective view of a vehicle  100 , in accordance with an embodiment. The vehicle includes a windshield  200  and at least one side window  210 . The solar sensor  160 / 170  is positioned on a dashboard  220  of the vehicle  100 . As discussed above, the memory  190 , illustrated in  FIG. 1 , stores vehicle geometry data. In one embodiment, for example, the memory  190  may store a series of multi-dimensional coordinate points  230 . In one embodiment, for example, each multi-dimensional coordinate point  230  may be measured relative to the position of the solar sensor  170 . In other words, the position of the solar sensor may be (0, 0, 0) and each other multi-dimensional coordinate point  230  is measured relative therefrom. 
       FIG. 3  is a partial perspective view of an interior of a vehicle  100 , in accordance with an embodiment. The interior of the vehicle  100  includes multiple seats  300 . As with the windshield and other windows of the vehicle  100 , multi-dimensional coordinate points  310  corresponding to the position of the seats  300  relative to the position of the solar sensor  170  are determined. In one embodiment, for example, the multi-dimensional coordinate points  310  of the vehicle seats  300  may be variable. The seats  300  of the vehicle may be movable in multiple dimensions. In other words, the seats could be brought forwards or backward, raised or lowered. An angle of the seat back relative to the seat bottom may also be variable. The seats could be adjusted manually or electronically via a power seat system (not illustrated). In one embodiment, for example, the position of the various components of the seat may be tracked by the power seat system. In other embodiments, for example, position sensors or cameras could track the position of the vehicle seats. The position of the seats could be reported to the controller  140  directly, or stored in the memory  190 . 
       FIG. 4  is a flow chart illustrating a method  400  for controlling a climate control system, in accordance with an embodiment. A controller, such as the controller  140  illustrated in  FIG. 1 , first traces solar rays passing through a windshield and side windows of a vehicle, depending upon the position of the sun with respect to the vehicle. (Step  410 ). In other words, the controller determines a path through the windshield and other windows of the vehicle that direct solar rays are travelling upon. The relative position information is based upon an elevation angle θ and a given azimuth angle Φ which may be based upon the data from a multi cell solar sensor or GPS information from a GPS receiver. The solar ray elevation angle θ corresponds to an angle of the traced solar ray relative to a horizon (i.e., the ground) and a zenith. The solar ray azimuth angle Φ corresponds to an angle of the solar ray relative to a reference vector, such as a vector corresponding to the vehicle driving direction. 
     The controller then converts the solar ray elevation angle θ and a solar ray azimuth angle Φ from the spherical coordinate system to the Cartesian coordinate system, with the position of the solar sensor  170  taken as the origin. (Step  420 ). A Cartesian coordinate (x, y, z) for a point P in the spherical coordinate system can be obtained by the following equations: x=r cos θ cos Φ, y=r cos θ sin Φ, z=r sin θ, where r corresponds to the magnitude of a vector OP, where O is the origin corresponding to the solar sensor illustrated in  FIG. 2 . The intensity of the solar ray may be determined, for example, from a single-cell solar sensor, such as the sensor  160  or a multi-cell solar sensor, such as the sensor  170  illustrated in  FIG. 1 . 
     The controller then determines the area of the seat(s) which is directly exposed to the solar rays. (Step  430 ). The controller first determines an intersection of the solar rays with the planes corresponding to seat backrest and seat cushion of the vehicle.  FIG. 5  is an illustration of the principals involved in this determination. Solar ray is depicted as a line L, starting from point P0 to P1 intersects a plane with a normal vector n and having the point V0 according to the following: A line L is determined according to: L: P0+r(P1−P0). An intersection of the line and the plane occurs at a point PI along the line L, where r 1 =P1−P0 is determined according to equation 1: 
     
       
         
           
             
               
                 
                   
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     Here a.b is a dot product of vector a and vector b. Using an intersection criteria: 0≦r 1 ≦1 the controller determines the intersection point PI according to the following: PI=P0+r 1 (P1−P0). When the denominator in Equation 1 is zero, the line L is parallel to the plane or is in the plane. 
     The controller then projects the plane(s) of solar rays coming through the various windows of the vehicle onto the planes corresponding to the seat backrest and seat cushions of the vehicle.  FIG. 6  is an illustration of the principals involved in this determination. The controller follows an intersection of ray/line starting from the grid points of the various windows onto the respective plane of the vehicle component when traversed in the direction of solar rays. In one embodiment, for example, a parametric plane equation for defining the plane(s) of rays could be determined by the following: V(s, t)=V0+s I (V1−V0)+t I (V2−V0). The equation can be reduced to V(s, t)=V0+s I u+t I v, where u=V1−V0, v=V2−V0, w=PI−V 0  illustrated in  FIG. 6 . Solving for w=s I u+t I v, s I  and t I  can be determined via the following equations: 
     
       
         
           
             
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     Where intersection point PI is in the plane, if 0≦s I ≦1, 0≦t I ≦1. If s I &lt;0, s I &gt;1, t I &lt;0, or t I &gt;1, intersection point PI is outside the rectangular plane bounded by (V0,V1,V2). Here s I  and t I  are the relative weighing of intersection point on the line defined by (V0, V1) and the line defined by (V0, V2), respectively. Values of s I  and t I  in the range (0,1), indicates that the intersection point is bounded by line (V0, V1) and (V0, V2), respectively. 
     The controller then determines the exposed area of the seats or other vehicular components being monitored for solar rays.  FIG. 7  illustrates the principals involved in finding the exposed area of the seats or other vehicular components being monitored for solar rays. Adjacent points of intersection of rays from grid points of the windows of a vehicle onto the seat plane are joined by lines. The intersection of these lines and the vectors/lines joining grid points of the seats is then determined by the controller. In  FIG. 7 , intersection points PI, PI′, PI″, PI′″, corresponding to the boundary lines of the projected solar plane, are denoted by U0, U1, U3, U4 and the grid points of the seat are denoted by V0, V1, V2, V3. The intersection of the lines of the projected solar plane and the planes corresponding to the seats or other vehicular components being monitored for solar rays can be determined by the following equations: 
               s   I   P     =         (       (       V   ⁢           ⁢   1     -     V   ⁢           ⁢   0       )     ×     (       U   ⁢           ⁢   0     -     V   ⁢           ⁢   0       )       )     ·     (       (       U   ⁢           ⁢   1     -     U   ⁢           ⁢   0       )     ×     (       V   ⁢           ⁢   1     -     V   ⁢           ⁢   0       )       )           (       (       V   ⁢           ⁢   1     -     V   ⁢           ⁢   0       )     ×     (       U   ⁢           ⁢   1     -     U   ⁢           ⁢   0       )       )     2                     t   I   P     =         (       (       U   ⁢           ⁢   1     -     U   ⁢           ⁢   0       )     ×     (       U   ⁢           ⁢   0     -     V   ⁢           ⁢   0       )       )     ·     (       (       U   ⁢           ⁢   1     -     U   ⁢           ⁢   0       )     ×     (       V   ⁢           ⁢   1     -     V   ⁢           ⁢   0       )       )           (       (       V   ⁢           ⁢   1     -     V   ⁢           ⁢   0       )     ×     (       U   ⁢           ⁢   1     -     U   ⁢           ⁢   0       )       )     2             
where an intersection point is used, if 0≦s I   P ≦1,0≦t I   P ≦1. s I   P  and t I   P  are indeterminate (zero divided by zero) if the two lines are parallel.
 
     Once the intersection points are determined, the controller can calculate the area of the seats or other vehicle components exposed to the solar rays. In one embodiment, for example, the controller may divide exposed areas of the seats to the solar rays into triangles to calculate the total area of exposure for a given azimuth angle and a given elevation angle. Disuniting the polygonal exposed area of the seats or other vehicle components to the solar rays into triangle is easy for calculation of the total exposed area and is also accurate. This principle is illustrated in  FIG. 8 . The area of each triangle is calculated and the sum of areas of triangles is calculated to determine total area of exposure of each seat to the solar rays. 
     The controller then modifies the air flow, temperature and air distribution from the climate control system based upon the areas determined to be exposed to solar rays. (Step  440 ). In one embodiment, for example, a percent directional sun effect for each occupant is calculated using the solar intensity (obtained from a solar sensor), glass transmissivity (a property of a glass could be obtained, for example, from the glass manufacturer), and the exposed area of the seats as follows. 
     
       
         
           
             
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     Where A e  and A comp  are the exposed area and total area of the seat or other vehicle component to be monitored for solar rays, respectively, λ g  is the transmissivity of the vehicle glass, and I solar  and I max  are the measured solar intensity and the maximum expected solar intensity. A ratio of the exposed area, A e  and the total area of the seat, A comp  is used to calculate percent exposure of the seat/occupant. The directional sun effect determined from the solar intensity, glass transmissivity and the percent exposure of the seat/occupant are used to change the duct outlet temperature, air flow and distribution of air inside the passenger compartment space to counteract the heat load from solar radiation, as illustrated in  FIG. 9 . In one embodiment, for example, the controller lowers the duct temperature, increases the airflow, and directs the air to the vent duct outlets when the seat or other area of the vehicle being monitored which corresponds to the duct has a larger directional sun effect. As seen in  FIG. 9 , a first graph  910  illustrates a duct air temperature in Celsius on the X axis, an outside air temperature in Celsius on the Y axis and an air flow in liters per second on the Z axis. The line labeled  920  corresponds to an exemplary duct temperature output when there is a 100% directional sun effect. The line labeled  930  corresponds to an exemplary duct temperature output when there is a 0% directional sun effect. The line labeled  940  corresponds to an exemplary air flow when there is a 0% directional sun effect. The line labeled  950  corresponds to an exemplary air flow when there is a 100% directional sun effect. In the graph labeled  960 , the X axis corresponds to a percent of air distribution and the Y axis corresponds to a duct temperature in Celsius. The line  970  corresponds to a percent air distribution when there is a 100% directional sun effect. The line  980  corresponds to a percent air distribution when there is a 0% directional sun effect. 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.