Abstract:
If both the electric heaters and combustion heaters constitute a hybrid type hot-air heater wherein both heaters are equipped with inlets adjacent to each other and are also housed within a frame and separated such that the air blowing systems of each heater are independent of each other, air leakage will occur in only the combustion heater during the heating operation in a direction opposite to the air blowing passage of the electric heater thereby resulting in dust adhering to the electric heater. If the electric heater is operated in this state, the dust will be heated and then burn causing a foul odor to occur when the heating operation first starts. Therefore, the air blowing fan  43  runs to remove any dust that entered into the air blowing passage before the electric heater  4  runs when the electric heater unit  4,  equipped with an electric heater  44,  is performing a heating operation.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a hybrid hotair heater in which a plurality of heating means are incorporated in one frame.  
           [0003]    2. Description of the Related Art  
           [0004]    Jpn. Pat. Appln. KOKAI Publication No. 2000-9347, for example, describes a hybrid hotair heater in which a combustion heater portion and an electric heater portion are incorporated in a frame and one air blowing fan constitutes an air blowing system. In this case, if the air blowing system is controlled by the one air blowing fan, a quantity of generated heat is different between a case where the electric heater portion is used for heating in addition to the combustion heater portion and a case where only the combustion heater portion is used for heating while the electric heater portion is at rest, so that to prevent overheating it is necessary to make different a quantity of air to be sucked in the frame between these two cases, thus making it difficult to operate the combustion heater stably because of a difference in quantity of combustion air.  
           [0005]    Therefore, is may be considered to arrange the combustion heater and the electric heater one above the other in such a configuration that the air blowing fan as well as an inlet and an outlet may be provided for each of them to thereby make the respective air blowing systems independent of each other. In this case, the outlets and the inlets are provided adjacent to each other in, for example, a front face and a rear face of an appliance respectively.  
           [0006]    It is to be noted that in a case where a hybrid hotair heater is arranged as described above to provide an inlet in a combustion heater portion and that in an electric heater portion adjacent to each other, if only a combustion heater portion is operated for heating, as air around the inlet in this combustion heater is sucked in a frame, the air may in some cases flow back from an outlet in the electric heater portion to the inlet through an air blowing passage.  
           [0007]    In such a case, dust around the outlet is sucked in the air blowing passage of the electric heater portion and sticks to the electric heater provided in this air blowing passage. If the electric heater is operated in this condition, the dust is heated to burn, so that nasty smell occurs when heating starts, which is a problem. In this case, a filter is mounted over the inlet, but it is not desirable to mount a filter over the outlet of which hotair is blasted out, because the filter provides resistance against the hotair.  
           [0008]    In view of the above, it is an object of the present invention to provide a hybrid hotair heater that can prevent offensive smell from occurring when heating starts by use of an electric heater.  
         SUMMARY OF THE INVENTION  
         [0009]    To solve the above problem, a hybrid hotair heater according to the present invention incorporates in a frame at least two heater portions each of which has an air blowing passage leading from an inlet to an outlet which air blowing passage is provided with an air blowing fan and heating means, in such a configuration that the inlets in these heater portions may be formed adjacent to each other and that air blowing systems of the heaters may be independent of each other in partitioning, in which one of the heating means is used as an electric heater and the other is used as a combustion heater so that when an electric heater portion comprising this electric heater is operated for heating, the blowing fan may be operated prior to operation of the electric heater to thereby remove dust which has entered in the air blowing passage.  
           [0010]    According to the present invention, only the combustion heater portion is operated, so that if dust present around the outlet is sucked in the air blowing passage of the electric heater portion and sticks to the electric heater when air flows back from the outlet through the air blowing passage to the inlet in the electric heater portion, the dust which has entered into the air blowing passage is removed by operating the air blowing fan prior to operation of the electric heater, thereby preventing offensive smell from occurring when heating starts by use of the electric heater portion.  
           [0011]    In this case, since hotair is blasted out from the beginning of heating, it is preferable to once stop operation of the air blowing fan of the electric heater portion when a predetermined lapse of time has elapsed from a point in time of its start in operation and then operate the electric heater, thus restarting operation of the air blowing fan after elapsing of a predetermined lapse of time.  
           [0012]    Further, when only the combustion heater portion comprising the combustion heater is used for heating, each time a predetermined lapse of time elapses from starting of the heating, the air blowing fan of the electric heater portion can be operated for a constant lapse of time, to periodically remove dust stuck to the electric heater, thus quickly operating the electric heater portion when the electric heater portion is used in addition to the combustion heater portion. It is to be noted that the combustion heater may be a gas burner.  
           [0013]    As described above, a hybrid hotair heater according to the present invention has an effect that offensive smell can be prevented from occurring when heating starts by use of an electric heater. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a perspective view of a hybrid hotair heater according to the present invention;  
         [0015]    [0015]FIG. 2 is an explanatory vertical cross-sectional view of a configuration of the hybrid hotair heater according to the present invention;  
         [0016]    [0016]FIG. 3 is an explanatory flowchart of operations of the hybrid hotair heater according to the present invention;  
         [0017]    [0017]FIG. 4 is another explanatory flowchart of the operations of the hybrid hotair heater according to the present invention; and  
         [0018]    FIGS.  5 ( a ) and ( b ) are explanatory flowcharts of operations for stopping the hybrid hotair heater according to the present invention in operation. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    In FIGS. 1 and 2, a reference numeral  1  indicates a hybrid hotair heater according to the present invention. This hotair heater (hereinafter referred to as “appliance”)  1  has a box-shaped frame  11 . The frame  11  is provided on its upper face with an operation portion  2  for controlling heating of the appliance  1 . This operation portion  2  comprises a driving switch  21 , a display  22  for displaying set temperature and time, a driving mode setting switch  23  for instructing a microcomputer (not shown) provided in the appliance to make predetermined setting, and setting changing switches  24  disposed above and below the driving switch  21  respectively. In the frame  11 , there are incorporated a gas heater portion  3  on an upper side and an electric heater portion  4  on a lower side. A first outlet  12   a  and a second outlet  12   b  are formed in a front face of the frame  11  and a first inlet  13   a  and a second inlet  13   b  are formed in a rear face of the frame  11  to face the gas heater portion  2  and the electric heater portion  3  respectively so that, as described later, two air blowing fans may be used to make an air blowing system of the gas heater portion  3  and that of the electric heater portion  4  independent of each other.  
         [0020]    The gas heater portion  3  comprises a gas burner  30  serving as a combustion heater and a first air blowing fan  31  which is arranged below the gas burner  30  and which supplies the gas burner  30  with combustion air and mixes combustion gas from this gas burner  30  with air sucked through the first inlet  13   a  in the frame  11  to blast them out to a room. The gas burner  30  is an all primary air burner and has a burner body  30   a  in which there are formed a fuel/air inlet  301  faced by a gas nozzle (not shown) mounted to a tip of a gas tube connected with an electromagnetic safety valve and a proportional control valve (not shown) which are arranged in the frame  11  and a mixer tube portion  302  communicating with this inlet  301 . On an open upper face of the burner body  30   a , a ceramic combustion plate  303  having a plurality of flame ports provided therein in a row is mounted via a distribution plate (not shown). This gas burner  30  is contained in a combustion frame  304 .  
         [0021]    In the frame  11 , there is also provided a diversion plate  51  in such a manner as to surround an upper side of the combustion chamber  304  and so that when  1  first air blowing fan  31  described later is operated, air sucked through the first inlet  13   a  in the frame  11  and combustion gas from the combustion chamber  304  may be partitioned from each other until they flow by a predetermined distance. In the frame  11 , there is provided a partition  53  in such a manner as to cover this diversion plate  51  and so that an air passage  52  may be formed to lead to the first air blowing fan  31  between itself and the diversion plate  51 .  
         [0022]    The air blowing fan  31  arranged below the burner body  30   a  has a housing  311  in which a air blowing duct  31  la leading to the first outlet  12   a  is formed. In the housing  311 , there is arranged a cross-flow type first moving vane  312  connected to a first motor (not shown) whose rotation speed can be controlled. In this case, the air passage  52  and an internal space of the housing  311  communicate with each other through an upper-face opening  311   b  in the housing  311 .  
         [0023]    In such a manner, an air blowing system of the gas heater portion  3  leading from the first inlet  13   a  to the first outlet  12   a  is formed. In this configuration, when the first motor is driven to rotate the first moving vane  312 , air in the room is sucked through the inlet  13   a  in the frame  11 , so that the air is supplied to the inlet  301  in the burner body  30   a  and flows through the air passage  52 . In this case, if fuel gas is sprayed through a gas nozzle to the inlet  301 , an air-fuel mixture is supplied to the flame port plate  303 . It is to be noted that an air/fuel ratio is adjusted by controlling the first motor to control a rotation speed of the first moving vane  312 .  
         [0024]    Combustion gas from the combustion chamber  304  passes through a combustion gas passage  54  on an inner side of the diversion plate  51  and is sucked toward the first air blowing fan  31 . air sucked through the first inlet  13   a  passes through the air passage  52  and undergoes heat exchange through the diversion plate  51  and then is mixed with the combustion gas to be cooled and flow through the opening  311   b  into the housing  311 . Then, hotair released through the outlet  12   a  to the room.  
         [0025]    On the other hand, the electric heater portion  4  is contained in a case  41  made of resin and has an air blowing passage  42  leading from the second inlet  13   b  to the second outlet  12   b . In this case, to miniaturize the electric heater portion  4 , the air blowing passage  42  is formed as bent in a direction from an upper side of the appliance  1  to a horizontal side. A bent portion  42   a  obtained by thus bending this air blowing passage  42  is provided with a second air blowing fan  43 . The second air blowing fan  43  comprises a second motor (not shown) whose rotation speed can be controlled and a cross-flow type second moving vane  431  connected to this second motor and arranged on the bent portion  42   a . On a downstream side of this bent portion  42   a , there are provided eight sheathed heaters  44  in such a manner as to intersect with air flowing through the air blowing passage  42 .  
         [0026]    In such a manner, an air blowing system of the electric heater portion  4  leading from the second inlet  13   b  to the second outlet  12   b  is formed. If, in this configuration, the second motor is driven to rotate the second moving vane  431 , air in the room is sucked through the second inlet  13   b  in the air blowing passage  42  and heated while it passes around the sheathed heaters  44  and then is released through the second outlet  12   b  to the room as hotair. It is to be noted that the first and second outlets  12   a  and  12   b  are formed adjacent to each other in such a manner that hotair blasted out of the first air blowing fan  31  and hotair blasted out of the second air blowing fan  43  may flow into each other.  
         [0027]    If the first inlet  13   a  and the second inlet  13   b  are adjacent to each other in a case where the appliance  1  is configured as described above, when the first air blowing fan  31  is operated to operate only the gas heater portion  3  for heating and suck air around this first inlet  13   a  in the frame  11 , correspondingly, the air may in some cases flow back from the second outlet  12   b  through the air blowing passage  42  to the second inlet  13   b  as indicated by an arrow in FIG. 2.  
         [0028]    In this case, dust around the second outlet  12   b  is sucked in the air blowing passage  42  and sticks to the sheathed heaters  44  in this air blowing passage  42 . If the sheathed heaters  44  are operated in this condition, the dust is heated to burn, thereby generating nasty smell at the beginning of driving. According to the present embodiment, before the electric heater portion  4  is operated for heating, the second air blowing fan  43  is operated for a constant lapse of time to perform so-called pre-purge, thereby removing dust which has entered into the air blowing passage  42 .  
         [0029]    Next, how to heat the appliance  1  according to the present invention is described with reference to FIG. 3. When the driving switch  21  is turned ON in a condition where the appliance  1  is at rest (S 10 ), settings stored in a control unit when this appliance  1  is stopped in heating last time are displayed on the display  22 , whereupon heating starts under the settings. In this case, the driving mode setting switch  23  may be pressed to change a heating mode (S 11 ) or the setting changing switch  24  may be pressed to change a set temperature. In the present embodiment, the heating mode can be selected from three modes where only the gas heater portion  3  is operated, where only the electric heater portion  4  is operated, and where the gas heater portion  3  and the electric heater portion  4  are operated simultaneously.  
         [0030]    If the electric driving mode is set (S 12 ), the electric heater portion  4  is used for heating. In this case, the process decides whether a current room temperature detected by a room temperature detection sensor (not shown) provided in the frame  11  is lower than a set room temperature by a predetermined temperature (1° C.) or more (S 13 ) and, if such is the case, operates the second air blowing fan  43  (S 14 ) to perform pre-purge, thereby removing dust stuck to the sheathed heaters  44 . Then, when a predetermined lapse of time (e.g., 10 seconds) has elapsed from a point in time of start of operation of the second air blowing fan  43 , the process once stops this air blowing fan  43  in operation (S 15 ). Next, the process operates the sheathed heaters  44  to perform pre-heating (S 16 ) and restarts operation of the second air blowing fan  43  (S 17 ) to blast hotair out of the second outlet  12   b . It is thus possible to prevent offensive nasty smell from occurring at the beginning of heating by use of the electric heater portion  4  and also to blast hotair out from the beginning. It is to be noted that the sheathed heaters  44  may be operated after the predetermined lapse of time (10 seconds) has elapsed from a point in time of start of operation of the air blowing fan  43 .  
         [0031]    When the electric heater portion  4  is being operated for heating, the process decides whether a current room temperature detected by the room temperature detection sensor is higher than a set room temperature by a predetermined temperature (1° C.) (S 18 ) and, if such is the case, stops the sheathed heaters  44  in operation (S 19 ). In this case, to perform so-called post-purge for releasing residual heat out of the air blowing passage  42 , the process operates the second air blowing fan  43  for a predetermined lapse of time (90 seconds) from a point in time of stopping of operation of the sheathed heaters  44  and stops it (S 20 ). It is to be noted that also if the driving switch  21  is turned OFF when the electric heater portion  4  is being operated for heating, post-purge is performed to release the residual heat out of the air blowing passage fan  42 .  
         [0032]    Next, as shown in FIG. 4, when the mode where the electric and gas heaters are operated is set (S 21 ), the process operates the first blowing fan  31  (S 22 ) and ignites the gas burner  30  (S 23 ). Next, when a predetermined lapse of time (45 seconds) elapses from a point in time of start of operation of the air blowing fan  31 , the second air blowing fan  43  is operated (S 24 ) to perform pre-purge. Then, when a predetermined lapse of time (10 seconds) elapses from a point in time of start of operation of the second air blowing fan  43 , the process once stops the second air blowing fan  43  in operation (S 25 ). Next, the process decides whether a current room temperature detected by the room temperature detection sensor is lower than a set room temperature by a predetermined temperature (2° C.) or more (S 26 ) and, if such is the case, operates the sheathed heaters  44  (S 27 ) to perform pre-heating and then operates the second air blowing fan  43  (S 28 ) to operate the electric and gas heater portions  3  and  4  for heating.  
         [0033]    When the gas and electric heater portions  3  and  4  are being operated for heating, the process decides whether a current room temperature detected by the room temperature detection sensor is higher than a set room temperature by a predetermined temperature (2° C.) (S 29 ) and, if such is the case, stops the sheathed heaters  44  in operation (S 30 ), to automatically switch to heating by use of only the gas heater portion  3 . In this case, the process stops the second air blowing fan  43  after performing post-purge by operating the it for a predetermined lapse of time (90 seconds) from a point in time of stopping of operation of the sheathed heaters  44  (S 31 ). Next, the process decides whether a predetermined lapse of time (one hour) has elapsed from a point in time of stopping of operation of the sheathed heaters  44  (S 32 ) and, if. such is the case, operates the second air blowing fan  43  (S 33 ) and, in 10 seconds, stops the second air blowing fan  43  in operation (S 34 ). It is thus possible to periodically remove dust stuck to the sheathed heaters  44  and quickly operate the electric heater portion  4  when it is to be operated in addition to the gas heater portion  3 .  
         [0034]    Next, as shown in FIG. 5A, if the power switch  21  is turned OFF when the gas and electric heater portions  3  and  4  are being operated for heating in the mode where both of them are used (S 41 ), the process puts out the gas burner  30  and stops the sheathed heaters  44  in operation (S 42 ). Next, the process operates the first and second air blowing fans  31  and  43  for a predetermined lapse of time (90 seconds) from a point in time of stopping of operation of the gas burner  30  and the sheathed heaters  44  to perform post-purge and then stops them (S 43 , S 44 ). If, on the other hand, the power switch  21  is switched OFF when the electric heater portion  4  is stopped in operation in the mode where both of them are used (S 51 ), the process puts out the gas burner  30  and operates the second air blowing fan  43  (S 52 ). The, when a predetermined lapse of time (10 seconds) has elapsed from a point in time of start of operation of the second air blowing fan  43 , the process stops this second air blowing fan  43  in operation (S 53 ) and, in 90 seconds after extinguishing of the gas burner  30 , stops the first air blowing fan  31  engaged in post-purge (S 54 ). It is to be noted that if the power switch  21  is turned OFF when the gas heater portion  3  is being operated for heating, the fan is stopped along the same procedure as that of FIG. 5B.  
         [0035]    Although the above embodiment has been described with reference to an example where the gas burner is used as a combustion heater, the present invention is not limited to use of the gas burner; for example, any burner such as an oil burner may be used as far as it generates heat by combustion.