Abstract:
A vehicle heating, ventilation, and air conditioning system includes front and rear HVAC systems. A controller receives data from front and rear control panels and controls the front and rear HVAC systems. Actuating a rear manual button on the front control panel allows control of the rear HVAC system via the rear control. Engine coolant temperature is used to judge if the vehicle has been inoperative for a long time. If the vehicle has not been inoperative for long, and the rear manual button was actuated prior to the vehicle shut down, rear manual control over the rear HVAC system is enabled. If the vehicle has been inoperative for a long time, or if the rear manual button was not actuated immediately prior to vehicle shut down, rear manual control is not enabled, thereby preventing operation of the rear HVAC system by the rear control panel.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally directed toward vehicle heating, ventilation, and air conditioning control systems and, more specifically, toward such control systems. 
     2. Description of Related Art 
     Vehicle heating, ventilation, and air conditioning systems (hereafter HVAC systems) have conventionally included components and vents located in or around the dashboard. However, as is well known to anyone who has been in a vehicle having a conventional HVAC system, there is a significant difference in temperature between the front portion (hereinafter front cabin) and the rear portion (hereinafter rear cabin) of the cabin, especially on days with extreme conditions (hot, sunny days and cold days). Providing all of the vents at the front of the vehicle usually maintains uncomfortable temperature conditions for occupants in the rear cabin. Alternatively, if an effort is made to make the rear occupants comfortable, the front occupants are over-heated or over-cooled. 
     Accordingly, rear HVAC systems and controls in the rear cabin, which are in addition to the conventional front HVAC systems and controls in the front cabin, have been developed. Such vehicle HVAC control systems include parallel front and rear HVAC control panels connected to a controller. 
     In the conventional HVAC control system, the rear HVAC system is operable via input from either the rear control panel or the front control panel. The rear HVAC system can be controlled via input from the front control panel, but can only be controlled via input from the rear control panel when permitted by the front control panel through actuation of the rear manual button on the front control panel. When the rear manual button is not actuated, the rear HVAC system is controlled via input from the front control panel. However, when the rear manual button is actuated, the rear HVAC system is controlled via input from the rear control panel. 
     Further, with the conventional HVAC control system, the rear manual button on the front control panel is automatically de-actuated every time the vehicle is turned off. Accordingly, for the rear HVAC system to be controlled via input from the rear control panel, the rear manual button must be actuated by the front occupant every time the vehicle is started. This standard resetting procedure ensures that subsequent to restarting of the vehicle, occupants of the front cabin only intentionally relinquish control of the rear HVAC system to the rear control panel. Clearly, it is futile to give control of the rear HVAC system to the rear control panel if the rear cabin is unoccupied. Therefore, by de-actuating the rear manual button when the vehicle is turned off and thus deactivating the rear control panel, the rear HVAC system is not inadvertently controlled by the rear control panel after the vehicle is restarted. This is especially useful when there are no occupants in the rear cabin after the vehicle is restarted. 
     However, the foregoing conventional HVAC control system suffers from a number of disadvantages. For example, when occupants are still present in the rear cabin after the vehicle restart, the rear manual button must again be actuated to allow control of the rear HVAC system by input from the rear control panel. Having to actuate the rear manual button after every restart can be inconvenient for the front cabin occupant. Furthermore, waiting for the rear manual button to be actuated can be annoying for the rear cabin occupant. 
     Therefore, there exists a need in the art for a vehicle HVAC control system that provides rear occupants with improved control over the rear HVAC system. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward a device and method that selectively permits control over a rear HVAC system with a rear control panel subsequent to a vehicle restart. 
     More specifically, the present invention utilizes engine coolant temperature to determine if the vehicle has been inoperative for a long period of time. If the vehicle has been inoperative for only a short period of time, the rear control panel is permitted to continue controlling the rear HVAC system, if such action was allowed prior to the vehicle being turned off. Alternatively, if, based upon the coolant temperature, the vehicle is determined to have been inoperative for a long period of time, the rear control panel is prevented from controlling the rear HVAC system unless a rear manual button on a front control panel is actuated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and further features of the invention will be apparent with reference to the following description and drawings, wherein: 
         FIG. 1  is a side view of a vehicle with an HVAC control system of the present invention; 
         FIG. 2  is a perspective view of a front cabin of the vehicle of  FIG. 1 ; 
         FIG. 3  is a perspective view of a rear cabin of the vehicle of  FIG. 1 ; 
         FIG. 4  is a schematic diagram illustrating the relationship between various components of the HVAC control system; and 
         FIG. 5  is a flowchart illustrating a method according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1-4 , an HVAC control system  10  for use in a vehicle  12  according to the present invention is shown. The vehicle  12  is comprised of three areas including an engine compartment  14 , a cabin  16 , and a storage compartment  18 . An engine  20 , a radiator  22 , a radiator fan  24 , and a coolant temperature sensor  26  are located in or around the engine compartment  14 . 
     The cabin  16  is bounded by a floor  28 , a roof  30 , doors (not shown), the engine compartment  14 , and the storage compartment  18 . A front cabin  32  and a rear cabin  34  comprise the cabin  16 . A dashboard  36 , front outlets  38 , a front control panel  40 , and a front HVAC system  42  are located in the front cabin  32 . A rear console  44 , located in the rear cabin  34 , includes rear outlets  46 , a rear control panel  48 , and optionally a rear HVAC system  50 . Located on the rear console  44  are a rear temperature display  52  and a rear input device  54  for changing a rear set temperature (T set-r ). 
     For ease of understanding, since the rear HVAC system  50  is similar to the front HVAC system  42  in function and structure, several of the components of the rear HVAC system  50  are not illustrated. Moreover, insofar as the front and rear HVAC systems, apart from the improvements provided by the present invention, may be otherwise generally conventional, they are not described at length hereinafter. In this regard, should more information regarding front and rear HVAC systems be desired, reference should be made to U.S. Pat. No. 7,156,167 to Errington et al. and U.S. Pat. No. 6,304,803 to Dao, both assigned to Honda Giken Kogyo Kabushiki Kaisha, the entire disclosures of which are hereby expressly incorporated by reference into this application. 
     Located on the dashboard  36  are a temperature display  56 , a front input device  58  for changing a front set temperature (T set-f ), a rear manual button  60 , and the front outlets  38  for dispersing conditioned air. Optionally, the front control panel  40  can also display the rear set temperature (T set-r ). Further, the front input device  58  can be used to change the rear set temperature (T set-r ). Located in or behind the dashboard  36  is a controller  62 , which is part of the control system  10 . As is specifically shown in  FIG. 4 , the control system  10  also includes the coolant temperature sensor  26  and the cabin temperature sensor  64 . 
     The coolant temperature sensor  26  and the cabin temperature sensor  64  are illustrated as being disposed at distinct locations in the engine compartment  14  and the front cabin  32 . However, it is considered clear that other locations in the vehicle  12  also offer appropriate positions for placement of the sensors  26 ,  64 . For example, the coolant temperature sensor  26  could be placed anywhere near where coolant flows that would allow accurate measurement of the coolant temperature (T w ). The coolant temperature sensor  26  is illustrated as being of a contact type, however use of non-contact measurement type devices is also envisioned. 
     Operation of the vehicle  12  causes the engine  20  to gain heat from the combustion process. As the engine  20  operates, the coolant circulates through the engine  20  and absorbs heat. When the coolant enters the radiator  22 , the radiator fan  24  ensures that an adequate amount of air blows through the radiator  22  to sufficiently cool the coolant. Next, the coolant leaves the radiator  22  and enters the engine  20  to again absorb heat from the combustion process. It is noted that the coolant temperature (T w ) is measured with the coolant temperature sensor  26  after the coolant leaves the radiator  22 . However, as previously disclosed, the coolant temperature (T w ) could be measured at a number of other locations. 
     In order to adjust air temperature in the front and rear cabins  32 ,  34 , an occupant (not shown) changes the set temperature (T set ) on the temperature display  56  with the front input device  58 . The set temperature (T set ) is communicated to the controller  62 . In addition, the controller  62  receives the coolant (T w ) temperature from the coolant temperature sensor  26 . Further, the rear manual button  60  status is sent to the controller  62 . If the rear manual button  60  is actuated, the rear HVAC system  50  is controlled based upon the rear control panel  48 . Alternatively, if the rear manual button  60  is not actuated, the rear HVAC system  50  is controlled based upon the front control panel  40 . The status of the rear manual button  60  is stored in the controller  62 , and is retained in the controller memory when the vehicle  12  is turned off, as will be apparent from the following discussion. 
     As shown in  FIG. 4 , the front and rear HVAC systems  42 ,  50 , the front and rear control panels  40 ,  48 , the cabin temperature sensor  64 , and the coolant temperature sensor  26  are electrically connected to the controller  62 . However, other means, such as for example wireless or fiber-optic communication means to connect the components with the controller  62 , are possible and contemplated. 
     Further, although it is not preferred, it is considered apparent that air could be heated and cooled by the front HVAC system  42  and then separately ducted into the rear cabin  34  to practice the present invention. 
     As mentioned hereinbefore, the front and rear HVAC systems  42 ,  50  heat and cool the front and rear cabins  32 ,  34 , respectively. If the rear manual button  60  is not actuated by the front occupant, the front and rear HVAC systems  42 ,  50  are operated based upon the settings from the front control panel  40 . Alternatively, if the rear manual button  60  is actuated by the front occupant, the front and rear HVAC systems  42 ,  50  are operated based upon the settings from the front and rear control panels  40 ,  48 , respectively. 
     A method of using the present invention is illustrated in  FIG. 5 . It is assumed that prior to Step  100 , the vehicle is operating. In Step  100 , the status of the rear manual button  60  is determined and stored in the controller  62 . Then, the vehicle  12  is turned off and the status of the rear manual button  60  is maintained in the controller  62  (Step  110 ). In Step  120 , the vehicle  12  is restarted. Then, the coolant temperature (T w ) is measured (Step  130 ). If the coolant temperature (T w ) is less than a predetermined temperature, the rear control panel  48  is disabled (i.e., rear manual control is not enabled; rear manual button status is ‘off’) and the rear HVAC system  50  is operated based upon the setting of the front HVAC system  42  (Steps  140 ,  150 ). If the coolant temperature (T w ) is greater than or equal to the predetermined temperature and the rear manual button  60  was previously actuated to provide control of the rear HVAC system  50  by the rear control panel  48  prior to the vehicle being turned off in Step  110 , the rear HVAC system  50  is operated based upon the setting of the rear control panel  48  (Steps  160 ,  170 ) (i.e., rear manual control is enable; rear manual button status is ‘on’). Alternatively, if the rear manual button  60  was not actuated prior to the vehicle being turned off in Step  110 , the rear HVAC system  50  is operated based upon the setting of the front control panel  40  (Step  160 ,  150 ) (i.e., rear manual control is not enabled; rear manual button status is ‘off’). 
     Experimentally, it has been determined that many times a coolant temperature below the predetermined temperature of approximately 60° C. indicates that the vehicle  12  had been inoperative for a long period of time in most conditions. In this regard, a long period of time is any period of time greater than about 15-20 minutes, while a short period of time is any time less than or equal to about 15-20 minutes. However, other conditions could yield a different determination of what temperatures would indicate that the vehicle  12  has been inoperative for a long period of time and this is possible and contemplated. 
     The present invention teaches that when the coolant temperature (T w ) is less than 60° C. upon vehicle restart, the controller  62  disables rear manual control by de-actuating the rear manual button  60 . However, when the coolant temperature (T w ) is greater than or equal to 60° C. upon vehicle restart, the setting of the rear manual button  60  prior to the vehicle  12  being turned off, either actuated or not actuated, is retained. Accordingly, if the rear manual button  60  was actuated prior to the vehicle  12  being turned off, the rear HVAC system  50  will be operated based upon the settings from the rear control panel  48  after restart. However, if the rear manual button  60  was not actuated prior to the vehicle  12  being turned off, the rear HVAC system  50  will be operated based upon the settings from the front control panel  40  after restart. 
     As previously described, with conventional HVAC systems, the rear manual button is automatically de-actuated every time the vehicle is turned off. Thus, in the conventional control arrangement, even if the vehicle is stopped for only a short period of time and then is restarted, occupants in the rear cabin cannot independently operate the rear HVAC system, unless the front occupant re-actuates the rear manual button. The present invention stores the rear manual button  60  status in the controller  62  and prevents the status of the rear manual button  60  from being reset when the vehicle  12  has only been inoperative for the short period of time, as determined by the temperature of the coolant (T w ). The rear occupant is therefore free to adjust the cabin temperature of the rear cabin  34 , if such action was allowed prior to the vehicle restart. Accordingly, the front occupant is freed from having to continually actuate the rear manual button  60  after short stops. Also, the rear occupant can make adjustments to the climate in the rear cabin  34  without bothering the front occupant to request that the rear manual button  60  be actuated. 
     As described hereinabove, the present invention solves many problems associated with previous type devices. However, it will be appreciated that various changes in the details, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art without departing from the principle and scope of the invention, as expressed in the appended claims.