Abstract:
A ventilation apparatus for a seat in which a positive temperature coefficient (PTC) heater is equipped in the ventilation apparatus which blows air to the seat in order to prevent overheating as well as to reduce heat loss. The ventilation apparatus includes a seat having a back and a seating section each of which has a discharge passage which discharges air toward a user. A blower is disposed in each discharge passage of the seat. A PTC heater is disposed inside each blower, and heats air that is being blown. A control unit simultaneously or individually controls the blowers and the PTC heaters. Accordingly, heating efficiency is improved and safety is increased.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to Korean Patent Application No. 10-2011-0122068, filed Nov. 22, 2011, the entire contents of which are hereby incorporated by reference herein. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates, in general, to a ventilation apparatus for a seat and, more particularly, to a ventilation apparatus for a seat in which a positive temperature coefficient (PTC) heater is equipped in the ventilation apparatus which blows air to the seat in order to prevent overheating as well as to reduce heat loss. 
       BACKGROUND 
       [0003]    In general, a seat of a vehicle serves to provide a cozy feeling of seating using a cushion. 
         [0004]    Recently, in response to the trends of consumers who demand convenience in addition to basic functionality for vehicle parts, a variety of convenience devices are being equipped in a vehicle seat. 
         [0005]    Among such convenience devices for a seat, most widely used is a seat-warming apparatus in which heating wires are disposed in the seat in order to provide warmth while driving in winter. Such a seat-warming apparatus is applied to seats of a variety of vehicles, since there are significant difficulties in designing and construction. However, the ability of the heating wires to make a user warm is limited. 
         [0006]    In order to solve this problem, an approach in which a cooler is disposed in the seat and a thermoelement is disposed in the cooler in order to supply heated air to the seat is used. However, when heating the air using the thermoelement, there is a problem in that a separate overheat-preventing means is essentially needed in order to prevent damage due to overheating. 
         [0007]    In addition, when the thermoelement is used, there is another problem in that a certain amount of air is discarded attributable to the characteristics of the thermoelement. 
       SUMMARY 
       [0008]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose a ventilation apparatus for a seat in which a positive temperature coefficient (PTC) heater is equipped in the ventilation apparatus which blows air to the seat in order to prevent overheating as well as to reduce heat loss. 
         [0009]    In order to achieve the above object, according to one aspect of the present invention, there is provided a ventilation apparatus for a seat which includes a seat comprising a back and a seating section, each of the back and the seating section having a discharge passage which discharges air toward a user; blowers each disposed in a corresponding discharge passage of the seat; PTC heaters each disposed inside a corresponding one of the blowers, the PTC heaters heating air that is being blown; and a control unit which simultaneously or individually controls the blowers and the PTC heaters. 
         [0010]    In an exemplary embodiment, each of the blowers may include a housing and a temperature sensor disposed inside the housing, the temperature sensor detecting a temperature of air which is taken in and transferring the detected temperature to the control unit. 
         [0011]    In an exemplary embodiment, the temperature sensor may be disposed between a blower fan disposed inside the blower and a corresponding one of the PTC heaters. 
         [0012]    In an exemplary embodiment, the control unit may control a rate at which the blower fan rotates and power which is supplied to the PTC heater depending on the temperature which is transferred from the temperature sensor. 
         [0013]    In an exemplary embodiment, the control unit may perform control so that one of the PTC heaters which is disposed in the back  1   a  is set to a higher temperature when the PTC heaters are operated, and so that one of the blower fans which is disposed in the back rotates at a slowed-down rate when no PTC heaters are operated. 
         [0014]    In an exemplary embodiment, each of the blowers may include a connecting duct in a predetermined portion thereof, the connecting duct being connected to a corresponding one of the discharge passages such that all of air that has passed through a place in which a corresponding one of the PTC heaters is disposed is supplied to a corresponding one of the discharge passages. 
         [0015]    In an exemplary embodiment, each of the PTC heaters may include a PTC device connected to an external power source to receive power therefrom; and heat exchange fins disposed on both sides of the PTC device. 
         [0016]    In an exemplary embodiment, each of the PTC heaters may further include a connector electrically connected to the PTC device, the connector being formed in a place of the housing which forms an outer surface of the blower, and the PTC heater being disposed in the place of the housing. 
         [0017]    According to embodiments of the invention, unlike the ventilation structure of the related art which uses heat wires, the ventilation apparatus for a seat does not need an overheat-preventing means attributable to the characteristics of the PTC heater, thereby reducing the number of parts and improving safety. 
         [0018]    While the thermoelement of the related art which uses heat wires wastes a certain amount of heat, the ventilation apparatus for a seat of the invention uses all air that is being blown for heating or ventilation, thereby improving efficiency. 
         [0019]    Furthermore, it is possible to simultaneously or individually control the heating and ventilation of the back and the seating section and to control the blower fans and the PTC heaters depending on the temperature that is detected by the temperature sensors, each of which is disposed between a corresponding blower fan and a corresponding PTC heater, thereby improving efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0021]      FIG. 1  is a configuration view schematically showing a ventilation apparatus for a seat according to an exemplary embodiment of the invention; 
           [0022]      FIG. 2  is a perspective view of the blower shown in  FIG. 1 ; and 
           [0023]      FIG. 3  is a cross-sectional view of the blower shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Reference will now be made in greater detail to a ventilation apparatus for a seat according to an exemplary embodiment of the invention with reference to the accompanying drawings. 
         [0025]      FIG. 1  is a configuration view schematically showing a ventilation apparatus for a seat according to an exemplary embodiment of the invention,  FIG. 2  is a perspective view of the blower shown in  FIG. 1 , and  FIG. 3  is a cross-sectional view of the blower shown in  FIG. 1 . 
         [0026]    As shown in  FIG. 1  to  FIG. 3 , the ventilation apparatus for a seat according to one exemplary embodiment of the invention includes a seat  1  which includes a back  1   a  and a seating section  1   b , blowers  10  which are mounted on the back  1   a  and the seating section  1   b , and positive temperature coefficient (PTC) heaters  20  each of which is disposed inside a corresponding blower  10  to heat air that is being blown. Also provided is a control unit which controls the blowers  10  and the PTC heaters  20 . Although it is described by way of example that the seat  1  is disposed inside the vehicle, the present invention is not limited to the vehicle seat but is applicable to all sorts of seats. 
         [0027]    Discharge passages  2   a  and  2   b  are formed inside the back  1   a  and the seating section  1   b . Air that is forcibly blown by the blowers  10  is introduced into the discharge passages  2   a  and  20   b,  which in turn discharge the air toward users. 
         [0028]    Each blower  10  includes a housing  11 , a blower fan  13  and a connecting duct  14 . The housing  11  has an inner storage space defined therein, and has an inlet in a side portion thereof. The blower fan  13  is disposed in the inlet side of the housing  11  in order to take in and forcibly blow outer air. The connecting duct  14  is provided in a predetermined portion of the housing  11 . The PTC heater  20  is disposed in an intermediate portion of the passage through which the air which is forcibly blown passes. A temperature sensor  12  is disposed in the passage through which the air that is blown is guided, between the blower fan  13  and the PTC heater  20 . 
         [0029]    The control unit  30  receives a temperature signal from a temperature sensor  12  which detects the temperature of the air that is blown by the blower fan  13 , and controls the rate at which the blower fan  13  rotates and the amount of heat which the PTC heater  20  generates. That is, the control unit  30  controls power that is supplied to the blower fan  13  and the PTC heater  20 . It is preferred that the control unit  30  controls the components such that the temperature of the PTC heater  20  which is disposed in the back  1   a  is set to be higher when the PTC heater  20  operates, i.e. at the time of heating. In contrast, is preferred that the control unit  30  control the components such that the rate at which the blower fan  13  disposed in the back  1   a  is slowed when no PTC heaters  20  operate, i.e. at the time of blowing. It is possible to freely adjust the amount of heat which the PTC heaters  20  generate and the rate at which the blower fan  13  rotates at the time of heating and blowing at the request of the user. 
         [0030]    Each PTC heater  20  includes a PTC device  21 , heat exchange fins  22  and a connector  23 . The PTC device  21  is connected to an external power source and radiates heat when receiving power from the external power source. The heat exchange fins  22  are mounted on both sides of the PTC device  21 . The connector  23  is electrically connected to the PTC device  21 , with one portion of the connector  23  being exposed to the outside and connected to the external power source. The PTC device  21  is a semiconductor device which experiences a sharp increase in electrical resistance when its temperature becomes equal to or higher than a Curie temperature (about 180° C. to 200° C.). The PTC device has the function of self-temperature control to maintain a predetermined heating temperature irrespective of surrounding temperatures when a voltage is applied thereto. Consequently, electrical resistance increases at a predetermined temperature (about 180° C. to 200° C.) or higher and the amount of current decreases, thereby lowering the temperature of heat. 
         [0031]    The connecting duct  14  is provided in a predetermined portion of the blower  10 , in particular, in a predetermined portion of the housing  11 , such that all air which is forcibly blown by the blower fan  13  can be supplied to the discharge passage  1   a  or  1   b  through the PTC heater  20 . The connecting duct  14  is connected to the corresponding discharge passage  1   a  or  1   b . Although it is preferred that the connecting duct  14  be integrally formed in the housing  11 , the connecting duct can be formed of a separate member, which is coupled to the housing. 
         [0032]    The ventilation apparatus for a seat of this embodiment as configured above provides indoor air to the seat by taking in indoor air using the blower  10  and changing the number of revolutions per unit time of the blower  10  in summer. In winter, ventilation apparatus heats the seat using the PTC heater  20  by sensing the temperature of air which is being taken in. The control unit for a seat is formed of one electronic control unit (ECU), and can simultaneously or individually control the blowers  10  and the PTC heaters  20  disposed in the back  1   a  and the seating section  1   b.    
         [0033]    The control unit adjusts the rate at which the blower fan  13  rotates and the amount of heat which the PTC heater  20  generates, depending on values which are set according to temperatures. In an example, when it is intended to heat the seat, the blower fan  13  is rotated while the PTC heater  20  is operated so that air which is forcibly blown by the blower fan  13  is heated while passing through the PTC heater  20 . All of the heated air is supplied to the discharge passages  1   a  and  1   b  through the connecting ducts  14 . The heated air which has been supplied to the discharge passages  1   a  and  1   b  is discharged toward the user who is sitting in the seat  1  so that heating is carried out. In addition, in the case of heating, it is preferred for the temperature at which the PTC heater  20  disposed in the back  1   a  generates heat to be set to be higher. However, it is also possible to set the temperature of one of the PTC heaters  20  to be higher or the temperatures of the PTC heaters  20  to be the same as required by the user. 
         [0034]    In another example, when only the blowing operation is intended for the seat, the operation of the PTC heaters  20  is stopped and only the blower fans  13  are rotated so that air that has been forcibly blown by the blower fans  13  is supplied to the discharge passages  1   a  and  1   b  through the connecting ducts  14 . The air that has been supplied to the discharge passages  1   a  and  1   b  is discharged to the user who is sitting in the seat  1  so that the user feels cool because of the air that is discharged. When the blowing operation is performed as described above, it is preferred for the blower fan  13  of the blower  10  which is disposed in the seating section  1   b  to be rotated faster than the blower fan  13  of the blower  10  which is disposed in the back  1   a . It is also possible to control the blower fans  13  which are disposed in the back  1   a  and the seating section  1   b  so that one blower fan rotates faster than the other blower fan  13  or both the blower fans rotate at the same rate. 
         [0035]    In addition, since the present invention uses the PTC heaters  20 , overheating is prevented owing to the characteristics of the PTC heaters  20 , thereby improving safety. It is also possible to reduce the number of parts since no separate overheat-preventing means is required. Each PTC heater  20  is provided with the connector  23  which is exposed out of the housing  11  such that the PCT heater can be easily connected to the external power source. 
         [0036]    Although the exemplary embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.