Seat air conditioning unit

Abstract

In an air conditioning unit for a seat, a duct forms a first outlet port through which air is blown to a seat surface and a second outlet port for discharging air. A heat exchanger unit having a thermoelectric effect element is disposed in the duct. An air volume control device is disposed in a duct to control a ratio of air introduced to the first outlet port to air introduced in an inlet port of the duct. In a draft mode, the air volume control device is operated such that the volume of air introduced to the first outlet port is larger than that in a normal mode. In a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the heat exchanger unit is smaller than that in the normal mode.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Applications No. 2005-138609 filed on May 11, 2005, No. 2006-46506 filed on Feb. 23, 2006, and No. 2006-46507 filed on Feb. 23, 2006, the disclosures of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a seat air conditioning unit that blows air from a seat surface.

BACKGROUND OF THE INVENTION

According to a seat air conditioning unit disclosed in Japanese Unexamined Patent Publication No. 10-44756, a temperature of air to be blown from a surface of a seat is increased or reduced through a heat exchanger unit having a Peltier element so as to improve a feeling of a passenger seating on the seat. A flow of air is produced by a blower unit and is introduced to the heat exchanger unit. In the heat exchanger unit, a first heat exchanger is disposed on a heat absorbing side of the Peltier element and a second heat exchanger is disposed on a heat radiating side of the Peltier element. Air that has passed through the first heat exchanger is blown from the seat surface, and air that has passed through the second heat exchanger is discharged to an outside of the seat.

In the seat air conditioning unit, when humidity between the passenger and the seat exceeds a predetermined level, an air mix door is opened so that the air passing through the first heat exchanger and the air passing through the second heat exchanger are mixed. The mixed air is blown from the seat surface. Accordingly, a moist feeling of the passenger reduces.

Also, there is another seat air conditioning unit that blows air inside of a passenger compartment from a seat surface without controlling a temperature of the air through a heat exchanger unit. In general, when the seat surface is hot, e.g., in summer, it is required to cool the seat surface in a short time (a transitional quick cooling operation) so as to improve a seat feeling. On the contrary, when the seat surface is very cold e.g., in winter, it is required to heat the seat surface in a short time (a transitional quick heating operation) to improve the seat feeling.

Regarding the former seat air conditioning unit, in the transitional state in which the quick cooling operation or the quick heating operation is required, the air that has passed through the first heat exchanger is blown from the seat surface. However, the air that has passed through the second heat exchanger is discharged to the outside of the seat as a waste heat. Therefore, it is difficult to blow a sufficient volume of air from the seat surface in the transitional state.

In the latter seat air conditioning unit, the air is not discharged as the waste heat even in the transitional state. Therefore, a sufficient volume of air is blown from the seat surface. However, the temperature of the air to be blown from the seat surface is not controlled. That is, the air to be blown from the seat surface has a temperature equal to a temperature of the air inside the passenger compartment. Therefore, it is difficult to provide a sufficient cooling effect, particularly, in a normal operation.

SUMMARY OF THE INVENTION

The present invention is made in view of the foregoing matter, and it is an object of the present invention to provide a seat air conditioning unit having a draft effect by blowing the large volume of air in a transitional state and a cooling or heating effect in a normal operation.

According to a first aspect of the present invention, an air conditioning unit for a seat has a duct, a heat exchanger unit, and an air volume control device. The duct defines a passage space, an inlet port through which air is introduced in the passage space, and a first outlet port through which the air is blown from a seat surface. The passage space of the duct separates into a first passage communicating with the first outlet port and a second passage space defining a second outlet port for discharging air to an outside of the seat.

The heat exchanger unit has a thermoelectric effect element, a first heat exchanger and a second heat exchanger. The thermoelectric effect element has a first side and a second side. One of the first side and the second side defines a heat absorbing side and the other one of the first side and the second side defines a heat radiating side. The heat radiating side and the heat radiating side are switched according to a flow direction of an electric current in the thermoelectric effect element. The first heat exchanger is disposed adjacent to the first side for performing heat exchange with air flowing in the first passage. The second heat exchanger is disposed adjacent to the second side for performing heat exchange with air flowing in the second passage.

The air volume control device is disposed in the duct for changing a ratio of air introduced to the first outlet port to the air introduced in the inlet port. In a normal mode, the thermoelectric effect element is energized and the air volume control device is operated so that air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is discharged through the second outlet port. In a draft mode, the air volume control device is operated so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode. In a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the first and second heat exchangers is smaller than that in the normal mode.

Accordingly, the ratio of air blown from the first outlet port to the air introduced in the inlet port is changed between the draft mode and the normal mode. Namely, in the draft mode, the volume of air blown from the seat surface is larger than that in the normal mode. Therefore, a draft effect improves. On the other hand, in the normal mode, the air blown from the first outlet port has an air conditioning effect through the first heat exchanger. Further, in the predetermined condition, the heat exchange rate in the heat exchanger unit is smaller than that in the normal mode, and the air volume control device is operated in the draft mode. Accordingly, the large volume of air is blown from the seat surface with reduced power consumption in the draft mode.

According to a second aspect of the present invention, the duct further defines a bypass passage for allowing the air introduced in the inlet port to bypass the first heat exchanger and the second heat exchanger. The bypass passage communicates with the first outlet port. The air volume control device is disposed in the duct for controlling the volume of air flowing in the bypass passage. In the normal mode, the thermoelectric effect element is energized. Also, the air passing through the first heat exchanger is introduced to the first outlet port and the air passing through the second heat exchanger is introduced to and discharged from the second outlet port. In the draft mode, the air volume control device is operated to increase a volume of air flowing through the bypass passage so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode.

Accordingly, the ratio of air introduced to the first outlet port to the air introduced in the inlet port is changed between the draft mode and the normal mode. Namely, in the draft mode, the volume of air blown from the seat surface is larger than that in the normal mode since the volume of air passing through the bypass passage is increased by the operation of the air volume control device. Accordingly, a draft effect on the seat surface improves. On the other hand, in the normal mode, the air blown from the first outlet port has an air conditioning effect through the first heat exchanger. Further, since the air is introduced to the first outlet port through the bypass passage, a pressure loss reduces. With this, the volume of air blown from the first outlet port increases.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:

FIG. 1 is a schematic diagram of a seat air conditioning unit according to a first example embodiment of the present invention;

FIG. 2 is a flow chart for showing a procedure of a control operation of the seat air conditioning unit according to the first example embodiment;

FIG. 3 is a chart for showing a timing of switching an operation mode between a draft mode and a normal mode and an electric current supply to a Peltier element in the control operation according to the first example embodiment;

FIG. 4 is a graph for showing a change of a seat temperature with time in a cooling down operation according to the first example embodiment;

FIG. 5 is a chart for showing a timing of switching the operation mode and an electric conduction state of the Peltier element according to a first modification of the first example embodiment shown in FIG. 3;

FIG. 6 is a flow chart for showing a procedure of the control operation according to the first modification shown in FIG. 5;

FIG. 7 is a chart for showing a timing of switching the operation mode and an electric conduction state of the Peltier element according to a second modification of the first example embodiment shown in FIG. 3;

FIG. 8 is a flow chart for showing a procedure of the control operation according to the second modification shown in FIG. 7;

FIG. 9 is a flow chart for showing a procedure of the control operation according to a second example embodiment of the present invention;

FIG. 10 is a flow chart for showing a procedure of the control operation according to a modification of the second example embodiment;

FIG. 11 is a schematic diagram of a part of the seat air conditioning unit according to a third example embodiment of the present invention;

FIG. 12 is a schematic diagram of a part of the seat air conditioning unit according to a fourth example embodiment of the present invention;

FIG. 13 is a schematic diagram of a part of the seat air conditioning unit according to a fifth example embodiment of the present invention;

FIG. 14 is a schematic diagram of a past of the seat air conditioning unit according to a sixth example embodiment of the present invention;

FIG. 15 is a schematic diagram of a part of the seat air conditioning unit according to a modification of the fourth example embodiment;

FIG. 16 is a schematic diagram of a part of the seat air conditioning unit according to another modification of the fourth example embodiment; and

FIG. 17 is a schematic diagram of a par of the seat air conditioning unit according to further another modification of the fourth example embodiment.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

A first example embodiment of the present invention will now be described with reference to FIGS. 1 to 4. As shown in FIG. 1, a seat air conditioning unit 1 of the first example embodiment is for example mounted to a seat bottom 21 of a seat 20. Alternatively, the seat air conditioning unit 1 can be mounted to a seat back 22.

The seat air conditioning unit 1 has a duct 2, a blower 4 and a heat exchanger unit 9. The duct 2 forms an inlet port 3 at one end (left end in FIG. 1) and the blower unit 4 is located upstream of the inlet port 3. The heat exchanger unit 9 is located downstream of the blower unit 4 in the duct 2. The blower unit 4 sucks air and blows the air into the duct 2. The seat air conditioning unit 1 is for example used in a vehicle. In this case, the blower unit 4 sucks air inside a passenger compartment. The blower unit 4 is disposed such that the air is fully introduced into a passage space of the duct 2 through the inlet port 3. In FIG. 1, an axial flow fan is illustrated as a fan of the blower unit 4. Instead, the blower unit 4 can have a centrifugal fan.

The passage space of the duct 2 is divided into a first passage 5 and a second passage 6 downstream of the inlet port 3. The duct 2 forms a first outlet 13 at a downstream end of the first passage 5 and a second outlet 14 at a downstream end of the second passage 6.

The first outlet 13 communicates with seat openings 24, so that the air introduced to the first outlet 13 is blown from a seat surface of the seat 20 through the seat openings 24. Here, the first passage 5, the first outlet 13 and the seat openings 24 form a channel through a conditioning air flows. The second outlet 14 serves as an opening for discharging a waste heat. The air (waste heat air) passing through the second passage 6 is discharged to an outside of the seat 20 through the second outlet 14.

The heat exchanger unit 9 is located between the inlet port 3 and the first and second outlets 13, 14 in the duct 2. The heat exchanger unit 9 includes a Peltier element 8, a first heat exchanger 10 and a second heat exchanger 11. The Peltier element 8 is provided as a thermoelectric effect element, and has a first side 8a and a second side 8b. In a cooling operation, the first side 8a functions as a heat absorbing side and the second side 8b functions as a heat radiating side. The heat absorbing side and the heat radiating side of the Peltier element 8 are switched according to a flow direction of electric current in the Peltier element 8.

The first heat exchanger 10 and the second heat exchanger 11 are arranged adjacent to the first side 8a and the second side 8b of the Peltier element 8, respectively, and use heat from the Peltier element 8.

The Peltier element 8 generally has a plate shape and is disposed to partly form a separation wall 7 between the first passage 5 and the second passage 6. The first heat exchanger 10 is located in the first passage 5 and the second heat exchanger 11 is located in the second passage 6. Namely, the air passing through the first heat exchanger 10 is fully introduced to the first outlet 13 through the first passage 5. Likewise, the air passing through the second heat exchanger 11 is fully introduced to the second outlet 14 through the second passage 6.

In the duct 2, a first door 12 is provided upstream of the second heat exchanger 11 as a first open and close member. The first door 12 is actuated by a door motor 31 through a link 32. The first door 12 is supported to move between a normal mode position (shown in dashed line in FIG. 1) and a draft mode position (shown in a solid line in FIG. 1). When the first door 12 is at the normal mode position, the first passage 5 and the second passage 6 are fully open. When the first door 12 is at the draft mode position, the second passage 6 is fully closed and the first passage 5 is open.

In the normal mode, that is, when the first door 12 is at the normal mode position, the air blown in the inlet port 3 is separated into the first passage 5 and the second passage 6. The air in the first passage 5 is cooled through the first heat exchanger 10 and introduced to the first outlet 13. The air in the second passage 6 is heated through the second heat exchanger 11 and introduced to the second outlet 14. In the example embodiment shown in FIG. 1, the second passage 6 is located on the second side 8b of the Peltier element 8. Thus, the heated air is discharged from the second outlet (heat waste opening) 14 to the outside of the seat 20.

In a draft mode, that is, when the first door 12 is at the draft mode position, the air introduced in the inlet port 3 is fully introduced into the first heat exchanger 10 and then introduced to the first outlet port 13 through the first passage 5. At this time, the air is restricted from passing through the second heat exchanger 11 by the first door 12. Accordingly, in the draft mode, the volume of air introduced in the first outlet 3 is substantially equal to the volume of air introduced to the inlet port 3, i.e., the volume of air produced by the blower unit 4. Namely, the volume of air blown from the first outlet 13 in the draft mode is larger than that in the normal mode, with respect to the same volume of air introduced in the inlet port 3.

Next, an electric control part of the seat air conditioning unit 1 will be described. The seat air conditioning unit 1 has an ECU 30 as a control means. The ECU 30 is constructed of a microcomputer and peripheral circuits.

The ECU 30 is connected to an inside air temperature sensor 33 and a seat temperature sensor 34. The inside air temperature sensor 33 is for example located adjacent to a suction side of the blower unit 4. The inside air temperature sensor 33 detects a temperature of the inside air to be introduced into the suction port 3 and outputs a signal Tr of the detected inside air temperature to the ECU 30.

The seat temperature sensor 34 detects a temperature of the seat 20 and outputs a signal Ts of the detected seat temperature 20 to the ECU 30. The seat temperature sensor 34 is for example located in a cushion member 34 of the seat 20 to avoid directly receiving an effect of the air blown from the seat openings 24 and an effect of the heat exchanging unit 9.

The ECU 30 controls the blower unit 4 in duty system to produce the necessary volume of air. Also, the ECU 30 controls the door motor 31 so that the first door 12 is operated to the draft mode position and the normal mode position.

Further, the ECU 30 controls the electric current supply to the Peltier element 8 in duty system so as to control the quantity of heat absorbed to and radiated from the Peltier element 8.

In a Peltier system of the first example embodiment, which is constructed of the Peltier element 8, the heat exchanger unit 9, the duct 2 and the blower unit 4, a value ΔPt is 5° C. Here, the value ΔPt is a difference between a temperature of air at an inlet side of the Peltier element 8, which corresponds to the inside air temperature Tr, and a temperature of air at an outlet side of the first heat exchanger 10 when the Peltier element 8 and the blower unit 4 are operated at a maximum level. Namely, the value ΔPt is a temperature difference created by the first heat exchanger 10 with respect the inside air temperature Tr, for cooling the seat surface of the seat 20.

Next, operation of the seat air conditioning unit 1 will be described. FIG. 2 shows a procedure of a control operation executed by the ECU 30. The control operation is started when an electric power supply to the ECU 30 is switched on. For example, the electric power supply to the ECU 30 is switched at a timing when a power switch (not sown) of the seat air conditioning unit 1 is turned on. Alternatively, the electric power supply to the ECU 30 is switched on according to a timing when a door of a parked vehicle is unlocked. In the latter case, the seat air conditioning unit 1 starts the operation in the draft mode before the passenger sits on the seat 20, so the temperature of the seat 20 is effectively reduced.

First, as an initial setting, the blower unit 4 is set to a shutdown condition and the Peltier element 8 is set to off. That is, the electric current to the Peltier element 8 is set to zero. Next, at a step S100, it is determined whether the seat temperature Ts is equal to or higher than a threshold value T1 (e.g., 30° C.). When it is determined that the seat temperature Ts is lower than the threshold value T1, the procedure proceeds to a step S160. At the step S160, a normal operation is performed.

When it is determined that the seat temperature Ts is equal to or higher than the threshold value T1 at the step S100, the blower unit 4 is operated at a step S110. At this time, the blower motor 4a is operated at a maximum level (e.g., duty ratio=99%) so that the fan 4 blows the maximum volume of air.

Next, at a step S120, it is determined whether the temperature difference between the detected seat temperature Ts and the inside air temperature Tr is equal to or greater than the value ΔPt (5° C.). In the draft mode, a large volume of air is blown from the seat openings 24 without operating the Peltier element 8. Namely, the cooling efficiency of the seat 20 enhances by the larger volume of air in the draft mode, as compared to a mode in which a relatively small volume of air cooled by the Peltier element 8 is blown from the seat openings 24. Therefore, when the temperature difference is equal to or higher than the value ΔPt, the operation is performed in the draft mode.

In the draft mode of the first example embodiment, the first door 12 is operated to the draft mode position in the condition that the Peltier element 8 is not energized and the blower unit 4 is operated at the maximum level (duty ratio=99%). Thus, the second passage 6 is closed. Namely, the inlet of the second heat exchanger 11 is closed, so the volume of air introduced to the second passage 6 is zero. Accordingly, the volume of air discharged from the second outlet port 14 is zero.

In the draft mode, the electric current is not supplied to the Peltier element 8. Therefore, even if the volume of air on the heat radiating side, i.e., the volume of air flowing in the second heat exchanger 11 is zero, it is less likely that the Peltier element 8 will be broken. Further, a power consumption reduces.

According to the operation in the draft mode, the air introduced to the inlet port 3 from the blower unit 4 almost passes through the first heat exchanger 10 and the first passage 5 and then introduced to the seat openings 24 through the first outlet 13, although there is a slight pressure loss. Accordingly, the ratio of air introduced to the first port 13 to the of air introduced in the inlet port 3 is a maximum. That is, the volume of the air blown from the outlet port 13 is at the maximum level, with respect to the maximum volume of air introduced in the inlet port 3.

Accordingly, in the draft mode, the air having the inside air temperature Tr is blown from the seat openings 24 at the maximum level. This operation is effective to immediately cool down the heated seat 20. For example, in a bright ambience in summer, the seat temperature Ts (e.g., approximately 60° C.) is immediately reduced at least to a first predetermined level P1 (Tr+ΔPt, e.g., 45 to 50° C.).

This draft mode operation is performed until the temperature difference between the seat temperature Ts and the inside air temperature Tr becomes smaller than the value ΔPt. Namely, at the step S120, when the difference between the seat temperature Ts and the inside air temperature Tr is smaller than the value ΔPt, the procedure proceeds to a step S140 to shift the operation from the draft mode to the normal mode.

In the normal mode, first, the first door 12 is operated to the normal mode position from the draft mode position to open the second passage 6, i.e., the inlet of the second heat exchanger 11. Thus, the volume of air introduced into the second passage 6 increases from zero to a predetermined level.

In this case, both of the first passage 5 and the second passage 6 are open. Thus, the air introduced in the inlet port 3 is separated into the first passage 5 and the second passage 6.

Then, at a step S150, the Peltier element 8 is energized to perform a duty system control of the normal operation. Then, the procedure proceeds to the step S160 to perform the normal operation.

In the normal operation at the step S160, the normal cooling down operation is performed in conditions similar to control conditions of a general seat air conditioning control using the Peltier element. For example, when the seat temperature Ts is equal to or higher than a comfortable temperature (e.g., 35° C.), the Peltier element 8 and the blower unit 4 are operated at maximum levels (duty ratio=99%).

When the seat temperature Ts reduces below the comfortable temperature (35° C.) as a result of the normal cooling down operation, a regular operation is performed to maintain the seat temperature at the comfortable temperature. In the regular operation, the Peltier element 8 and the blower unit 4 are operated at a half capacity (duty ratio=50%).

FIG. 3 shows a mode switching and an electric current supply to the Peltier element 8 with respect to the seat temperature Ts in the above control operation. As shown in FIG. 3, when the seat temperature Ts is equal to or higher than the threshold value T1, the draft mode is selected and the electric power is not supplied to the Peltier element 8. Then, the seat temperature Ts reduces below the first predetermined temperature P1 (Tr+ΔPt), the operation mode is switched to the normal mode and the electric current is supplied to the Peltier element 8.

Next, advantageous effect of the above control operation will be described with reference to FIG. 4. FIG. 4 shows the change of the seat temperature Ts in the cooling down operation with respect to an elapsed time.

At an initial point, i.e., when the elapsed time is zero, a temperature of outside air is 40° C. under bright sunlight. Also, the inside air temperature Tr is approximately 45° C., and the seat temperature Ts is 60° C. A dotted line A shows a change of the seat temperature Ts when the control operation is performed only in the draft mode (large volume of air, Pelier element off). A dashed line B shows the change of the seat temperature Ts when the control operation is performed only in the normal mode (Peltier element on, the second passage 6 open). A solid line C shows the change of the seat temperature Ts when the control operation is performed in the manner of the first example embodiment described above.

Here, a vehicle air conditioner starts its operation from the initial point. Thus, the inside air temperature Tr reduces to 40° C. several minutes (e.g., about 5 minutes) after an operation of the vehicle air conditioner is started. The inside air temperature Tr becomes a setting temperature (25° C., which is set by the vehicle air conditioner, in a regular state.

In the operation condition A, the inside air having the temperature Tr, which is 15 to 20° C. lower than the seat temperature Ts, is blown at an initial stage. Also, the large volume of air is blown. Thus, the operation condition A provides a cooling effect higher than that of the operation condition B. The passenger on the seat 20 is likely to feel airflow and cool.

As the time elapses, the seat temperature Ts reduces. When the seat temperature Ts approaches the inside temperature Tr, it is difficult to absorb heat of the seat 20 in the operation condition A. Thus, the seat temperature Ts reaches a level of saturation due to a body temperature of the passenger in the regular state.

In the operation condition B, even when the seat temperature Ts approaches the inside temperature Tr with the elapse of time, a high cooling effect is provided. Further, it is possible to cool the seat 20 to a temperature (e.g., equal to or lower than 35° C. in summer) that the passenger feels cold. Thus, the seat temperature Ts is effectively controlled by using the Peltier element 8.

Here, in the operation condition B, the electric power is continuously supplied to the Peltier element 8 without performing a temperature control. Thus, the line B shows a seat cooling capacity when the electric power is continuously supplied to the Peltier element 8.

As shown in the operation condition C, at an initial stage of the cooling down operation right after the operation of the seat air conditioning unit 1 is started, the seat temperature Ts is immediately reduced by the large volume of air in the draft mode. Then, when the seat temperature Ts approaches the inside temperature Tr, the operation mode is switched to the normal mode. Thus, the seat temperature Ts is positively controlled by using the Peltier element 8 in the normal mode. Accordingly, this control operation is effective to provide a cool feeling to the passenger.

The first example embodiment will be modified as follows. FIG. 5 shows a first modification of the first example embodiment. As shown in FIG. 5, when the seat temperature Ts is equal to or higher than a first predetermined temperature P1, the operation is performed in the draft mode in a condition that the Peltier element 8 is energized. In the first modification, the first predetermined temperature P1 is Tr+ΔPt+1° C. When the seat temperature Ts reduces below the first predetermined temperature P1 (Tr+ΔPt+1° C.), the Peltier element 8 is energized. Then, the seat temperature Ts reduces below a second predetermined temperature P2 (Tr+ΔPt), the operation mode is switched to the normal mode.

There is a time delay to reduce the temperature of the Peltier element 8 so as to have sufficient cooling effect after the electric current supply to the Peltier element 8 is started. Therefore, in the first modification, the Peltier element 8 is energized before the operation mode is switched from the draft mode to the normal mode. The temperature of air is immediately reduced at the same time as reducing the volume of air. Therefore, even if the volume of air is reduced, the passenger who has been satisfied with the draft feeling can feel cool at that timing.

The procedure of the control operation of the first modification will be described with reference to FIG. 6. Similar to the procedure shown in FIG. 2, when the seat temperature Ts is equal to or higher than the threshold value T1, the blower unit 4 is operated at the maximum level at the step S110.

Next, at a step S120a, it is determined whether the seat temperature Ts is lower than the first predetermined temperature P1 (Tr+ΔPt+1° C.). When the seat temperature Ts is equal to or higher than the first predetermined temperature P1, the operation is performed in the draft mode at the step S130.

Then, when the seat temperature Ts reduces below the first predetermined temperature P1, it is determined whether the seat temperature Ts is lower than the second predetermined temperature P2 (Tr+ΔPt) at a step S120b. When the seat temperature Ts is equal to or higher than the second predetermined temperature P2, the Peltier element 8 is energized at the step S150. Then, when the seat temperature Ts reduces lower than the second predetermined temperature P2, the operation mode is switched to the normal mode at a step S140. Then, the normal operation is performed at the step S160.

In the first modification of the first example embodiment, the difference between the first predetermined temperature P1 and the second predetermined temperature P2 is 1° C. This temperature difference can be modified to another fixed value or a variable value calculated based on the inside temperature Tr.

FIG. 7 shows a second modification of the first example embodiment. As shown in FIG. 7, when the seat temperature Ts is equal to or higher than a first predetermined temperature P1 (Tr+ΔPt), the operation is performed in the draft mode and the Peltier element 8 is not energized. When the seat temperature Ts reduces below the first predetermined temperature P1, the Peltier element 8 is energized. Then, when a predetermined time Et1 (e.g., 10 seconds) has elapsed since the Peltier element 8 was energized, the operation mode is switched to the normal mode. For example, the predetermined time Et1 is set by using a timer.

Also in the second modification, the Peltier element 8 is energized before the operation mode is switched from the draft mode to the normal mode. Accordingly, advantageous effects similar to those of the first modification are provided.

The control operation of the second modification will be described with reference to FIG. 8. The control operation shown in FIG. 8 is different from the control operation shown in FIG. 6 at steps S120c and S120d. The first predetermined temperature P1, which is the threshold value at the step S120c, is Tr+ΔPt. At the S120d, it is determined whether the predetermined time period Et1 has elapsed. Steps other than the steps S120c and S120d are similar to those of the first modification shown in FIG. 6.

In the control operations shown in FIGS. 2, 6, 8, the threshold value compared to the seat temperature Ts is set by using the inside temperature Tr and ΔPt. However, the threshold value can be changed based on a type of vehicle, a region in use, a user, or a use condition. Further, the threshold value can be a fixed value.

Next, a second example embodiment of the present invention will be described with reference to FIG. 9. In the second example embodiment, structure of the seat air conditioning unit 1 is similar to that of the first example embodiment. Thus, description of like structures will not be repeated. However, the control operation performed by the ECU 30 is different from that of the first example embodiment. Hereafter, the control operation of the second example embodiment will be described.

When the electric power supply to the ECU 30 is switched on, the initial setting is performed in a manner similar to the first example embodiment. Next, at a step S105, it is determined whether the inside temperature Tr detected by the inside air temperature sensor 33 is equal to or higher than a threshold value T2 (e.g., 30° C.). The threshold value T2 is can be changed based on a type of vehicle, a region in use, a user, or a use condition.

When the inside temperature Tr is lower than the threshold value T2, the procedure proceeds to step S160, so the normal operation is performed, similar to the first example embodiment.

When the inside temperature Tr is equal to or higher than the threshold value T2 at the step S105, the blower unit 4 is operated at the maximum level (duty ratio=99%) at the step S110, similar to the first example embodiment. Next, at a step S115, it is determined whether a predetermined time period Et2 (e.g., 2 minutes) has elapsed. The predetermined time period Et2 is previously set by the timer. The predetermined time period Et2 is changed based on various conditions such as an assumed use condition or a type of vehicle.

When it is determined that the predetermined time period Et2 has not elapsed at the step S115, the operation is performed in the draft mode at the step S130. In the draft mode, the Peltier element 8 is not energized, and the blower unit 4 is operated at the maximum level (duty ratio=99%), similar to the draft mode of the first example embodiment. In this condition, the first door 12 is operated to the draft mode position to close the inlet of the second heat exchanger 11. Thus, the volume of air discharged from the second outlet port 14 is zero.

According to the operation in the draft mode, since the second passage 6 is closed with the first door 12 in a condition that the electric current is not supplied to the Peltier element 8, the air introduced in the inlet port 3 almost introduced to the first outlet port 13 and blown from the seat openings 24. Thus, the large volume of air is blown from the seat openings 24. Accordingly, the seat temperature Ts is immediately reduced close to the inside air temperature Tr by the draft effect.

When the predetermined time Et2 has elapsed since the operation in the draft mode was started, that is, it is determined YES at the step S115, the operation mode is switched to the normal mode at the step S140. First, the first door 12 is operated to the normal mode position at which the second passage 6 is opened, i.e., the inlet of the second heat exchanger 11 is open. Thus, the volume of air introduced into the second passage 6 increases to the predetermined level from zero.

In this case, the first passage 5 and the second passage 6 are open. Thus, the air introduced in the inlet port 3 separates into the first passage 5 and the second passage 6. Then, similar to the first example embodiment, at the step S150, the Peltier element 8 is energized to perform the normal operation in duty system control. Then, the normal operation is performed at the step S160.

In the normal operation in the step S160, the normal cooling down operation is performed in conditions similar to control conditions of the general seat air conditioning control using the Peltier element. For example, when the seat temperature Ts is equal to or higher than the comfortable temperature (e.g., 35° C.), the Peltier element 8 and the blower unit 4 are operated at the maximum level (duty ratio=99%).

When the seat temperature Ts reduces below the comfortable temperature (35° C.) as a result of the normal cooling down operation, the regular operation is performed to maintain the seat temperature at the comfortable temperature. In the regular operation, the Peltier element 8 and the blower unit 4 are operated at a half capacity (duty ratio=50%).

Accordingly, the control operation of the second example embodiment provides advantageous effects similar to those of the first example embodiment.

In the second example embodiment shown in FIG. 9, the timing of switching the operation mode from the draft mode to the normal mode is determined based on the elapsed time Et2 at the step S115. However, the control operation of the second example embodiment will be modified as shown in FIG. 10. In FIG. 10, a step S125 for determining whether the inside temperature Tr is equal to or lower than a predetermined temperature T3 that is lower than the threshold value T2 is provided in place of the step S115 of FIG. 9. Accordingly, when the inside temperature Tr is equal to or lower than the predetermined temperature T3 that is lower than the threshold value T2, the draft mode operation is terminated and switched to the normal mode.

A third example embodiment will be described with reference to FIG. 11. As shown in FIG. 11, a second door 15 is provided as the first open and close member, in place of the first door 12 of the first and second example embodiments. Structures other than the second door 15 are similar to those of the first and second example embodiments. In FIG. 11, only the part from the inlet port 3 to the first and second outlet ports 13, 14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.

The second door 15 is located downstream of the heat exchanger unit 9. Further, the second door 15 is supported to open and close the second passage 6 at a position downstream of the second heat exchanger 11. When the second door 15 is at a position to close the second passage 6, an opening 15a formed on the separation wall 7 between the first passage 6 and the second passage 7 is open. Thus, the air passing through the second heat exchanger 11 flows into the first passage 5 through the opening 15a. When the second door 15 is at a position to close the opening 15a, the second passage 6 is fully open. Thus, the air passing through the second heat exchanger 11 is restricted from flowing into the first passage 5. The second door 15 is rotated by the door motor 31 through a link 32a, similar to the first door 12 of the first and second example embodiments.

In the third example embodiment, the ECU 30 performs the control operation in a manner similar to the first and second example embodiments shown in FIGS. 2, 6, 8, 9 and 10, except the operation of the second door 15. The second door 15 is operated in the following manner.

In the normal mode in which the Peltier element 8 is energized to have the cooling effect by the first heat exchanger 10 to have cooling effect, the second door 15 is operated to a normal mode position shown by dotted line in FIG. 11. Namely, the opening 15a is fully closed and the second passage 6 is open so that the air that receives heat from the Peltier element 8 through the second heat exchanger 11 is discharged from the second outlet port 14 as the waste heat.

Since the second door 15 is positioned to close the opening 15a and open the second passage 6 in the normal mode, the air is distributed in the manner similar to that in the normal mode of the first and second example embodiments.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and 10, the second door 15 is operated to a draft mode position shown by a solid line in FIG. 11. Namely, the second door 15 fully closes the second passage 6 and opens the opening 15a. After the termination of the draft mode, that is, at the step S140 of FIGS. 2, 6, 8, 9 and 10, the second door 15 is operated to the normal mode position shown by the dotted line in FIG. 11.

Accordingly, in the draft mode, the air passing through the second heat exchanger 11 flows into the first passage 5 through the opening 15a. Since both the air passing through the first heat exchanger 10 and the air passing through the second heat exchanger 11 are introduced to the first outlet port 13, the ratio of the air introduced to the first outlet port 13 to the air introduced to the inlet port 3 increases.

In the draft mode, the Peltier element 8 is not energized. Therefore, the air passing through the second heat exchanger 11 does not receive heat from the Peltier element 8 and has the temperature similar to the temperature of the inside air.

Also in the third example embodiment, advantageous effects similar to those of the first and second example embodiments are provided.

Next, a fourth example embodiment will be described with reference to FIG. 12. As shown in FIG. 12, the duct 2 has a bypass passage 16 and a third door 17 as a second open and close member, in place of the first door 12 of the first open and close member. Other structures are similar to those of the first and second example embodiments. In FIG. 12, only the part from the inlet port 3 to the first and second outlet ports 13, 14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.

The bypass passage 16 is disposed to allow the air to bypass the first heat exchanger 10. For example, the bypass passage 16 is located on the opposite side as the second heat exchanger 11, with respect to the first heat exchanger 10, in the first passage 5. The third door 17 is located adjacent to an inlet of the bypass passage 16 to open and close the bypass passage 16. The third door 17 is operated by the door motor 31 through a link 32b, similar to the first door 12 of the first and second example embodiments.

In the fourth example embodiment, the ECU 30 performs the control operation, in a manner similar to the first and second example embodiment, except the operation of the third door 17. The third door 17 is operated in the following manner, in place of the first door 12.

First, in the normal mode in which the Peltier element 8 is energized to have the cooling effect by the first heat exchanger 10, the third door 17 is operated to a normal mode position shown by dotted line in FIG. 12. Namely, the third door closes the bypass passage 16. Thus, approximately half of the air introduced in the inlet port 3 is cooled through the first heat exchanger 10. The cooled air passes through the first outlet port 13 and is blown from the seat openings 24.

The remaining half of the air is heated through the second heat exchanger 11 according to the operation of the Peltier element 8. The heated air is discharged from the second outlet port 14 to the outside of the seat 20. Since the third door 17 closes the bypass passage 16 in the normal mode, the air is distributed in a manner similar to that in the normal mode of the first to third example embodiments.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and 10, the third door 17 is operated to a draft mode position shown by solid line in FIG. 12. Namely, the third door 17 is positioned to fully open the bypass passage 16. After the termination of the draft mode, that is, at the Step S140 of FIGS. 2, 6, 8, 9, and 10, the third door 17 is operated to the normal mode position shown by the dotted line in FIG. 12.

Accordingly, the pressure loss in the first passage 5 reduces in the draft mode. Therefore, the volume of air introduced to the first outlet port 13 through the first passage 5 increases. Namely, the ratio of the air blown from the first outlet port 13 to the air introduced in the inlet port 3 increases, as compared to a case without having the bypass passage 16.

Also in the fourth example embodiment, advantageous effects similar to those of the first and second example embodiments are provided.

Similar to the above example embodiments, the Peltier element 8 is not energized in the draft mode. Therefore, power consumption reduces. However, since the inlet of the second heat exchanger 11 is always open and the air passing through the second heat exchanger 11 is always discharged from the second outlet port 14 to the outside of the seat 20, it is not always necessary to stop the electric current supply to the Peltier element 8.

Therefore, in the draft mode of the steps S110 in FIGS. 2, 6, 8, 9, and 10, the electric current can be supplied to the Peltier element 8. Thus, the air can be cooled through the first heat exchanger 10 and the cooled is blown from the first outlet port 13 in the draft mode.

In this case, the cooling effect in the draft mode is lower than that in the normal mode, because the volume of air in the bypass passage 16 increases. However, since the volume of air blown from the seat openings 24 increases, the draft effect improves. Thus, the seat temperature Ts is further reduced by the cooled air having the temperature lower than the inside temperature Tr.

Further, the volume of the air blown from the first outlet 13 is increased since the pressure loss in the first passage 5 is reduced. Therefore, a power required to the blower unit 4 reduces. Furthermore, noise effect reduces.

Next, a fifth example embodiment will be described with reference to FIG. 13. As shown in FIG. 13, the duct 2 has the second door 15 as the first open and close member, which is similar to the second door 15 of the third example embodiment, in place of the first door 12. Also, the duct 2 has the third door 17 as the second open and close member, which is similar to the third door 17 of the fourth example embodiment. Further, the duct 2 has the bypass passage 16. Other structures are similar to the first and second example embodiments. In FIG. 13, only the part from the inlet port 3 to the first and second outlet ports 13, 14 is illustrated. Further, like components are denoted by like reference characters and a description thereof is not repeated.

Similar to the third example embodiment, the second door 15 as the first open and close member is located downstream of the second heat exchanger 11 in the second passage 6. The second door 15 is operated to open and close the second passage 6 and the opening 15a formed in the separation wall 7. Similar to the fourth example embodiment, the bypass passage 16 is formed in the first passage 5 to allow the air to bypass the first heat exchanger 10. Also, the third door 17 as the second open and close member is located at the inlet of the bypass passage 16 to open and close the bypass passage 16. The second door 15 and the third door 17 are simultaneously operated by the door motor 31 through the links 32a, 32b.

Also in the fifth example embodiment, the ECU 30 performs the control operation in a manner similar to that of the first and second example embodiments, except the operation of the second door 15 and the third door 17. The second door 15 and the third door 17 are operated in the following manner.

First, in the normal mode in which the Peltier element 8 is energized to have the cooling effect by the first heat exchanger 10, the second door 15 is at the normal mode position shown by dotted line in FIG. 13. Also, the third door 17 is at a position shown by dotted line in FIG. 13. Namely, the second door 15 fully closes the opening 15a and fully opens the second passage 6 so that the air passing through the second heat exchanger 11 is discharged from the second outlet port 14 to the outside of the seat 20. The third door 17 closes the bypass passage 16. Thus, approximately half of the air introduced in the inlet port 3 is introduced to the first heat exchanger 10 and cooled. The cooled air is blown from the seat openings 24 through the first outlet port 13.

In the draft mode, that is, at the step S130 of FIGS. 2, 6, 8, 9, and 10, the second door 15 is operated to the position shown by solid line in FIG. 13. Also, the third door 17 is operated to the position shown by solid line in FIG. 13. Namely, the second door 15 fully closes the second passage 6 and fully opens the opening 15a. The third door 17 fully opens the bypass passage 16.

After the termination of the draft mode, that is, at the step S140 of FIGS. 2, 6, 8, 9, and 10, the second door 15 is operated to the position shown by solid line in FIG. 13. Also, the third door 17 is operated to the position shown by dotted line in FIG. 13.

Accordingly, in the draft mode, the air passing through the first passage 5 and the air passing through the second heat exchanger 11 are introduced to the first outlet port 13. Therefore, the ratio of the air introduced to the first outlet port 13 to the air introduced in the inlet port 3 increases, as compared to that in the normal mode.

Further, the pressure loss in the first passage 5 reduces since the bypass passage 16 is open in the draft mode. Therefore, the volume of air passing through the first passage 5 increases. Furthermore, since the air passing through the second heat exchanger 11 is introduced to the first passage 5 through the opening 15a, the volume of air blown from the first outlet port 13 is increased larger than that of the first to fourth example embodiments. In the draft mode, since the Peltier element 8 is not energized, the air passing through the second heat exchanger 11 does not receive heat from the Peltier element 8 and has the temperature similar to that of the inside air.

Also in the fifth example embodiment, advantageous effects similar to those of the first and second embodiments are provided.

The above example embodiments will be further modified in the following manner.

In the above example embodiments shown in FIGS. 11 and 12, the heat exchanger unit 9 are configured such that the air flows parallel to the Peltier element 8. Alternatively, a wall 10a of the first heat exchanger 10, which faces the bypass passage 16, can be formed with openings, as shown in FIG. 14.

For example, in the Peltier module including the Peltier element 8 and the first and second heat exchangers 10, 11, fins 10b, 11b are generally provided along the surfaces 8a, 8b of the Peltier element 8 for performing heat exchange. The fins 10b, 11b are sandwiched by walls 10a, 11. Here, the openings 10c are formed on the wall 10a. Instead of forming the openings 10c on the wall 10a, the wall 10a can be removed.

Accordingly, the air passing through the first heat exchanger 10 can flow upwardly toward the bypass passage 16. Therefore, the pressure loss of the air passing through the first heat exchanger 10 further reduces. In the example embodiment shown in FIG. 14, the openings 10c are exemplary employed in the structure shown in FIG. 12. The openings 10c can be employed in the structure shown in FIG. 13.

As a modification of the fourth example embodiment shown in FIG. 12, the first door 12 as the first open and close member can be arranged upstream of the second heat exchanger 11, as shown in FIG. 15. The first door 12 is operated by the door motor 31 through the link 32, similar to the first and second example embodiments. In this case, the ECU 30 performs the control operation in a manner similar to the first and second example embodiments. Here, the first door 12 is operated in the manner similar to those of the first and second example embodiments. The third door 17 is operated in the manner similar to that of the fourth example embodiment. In this case, the Peltier element 8 is not energized in the draft mode.

In the example embodiment shown in FIG. 12, the third door 17 is arranged at the upstream position of the bypass passage 16. Alternatively, the third door 17 can be arranged at a position downstream of the first heat exchanger 10, as shown in FIG. 16. Alternatively, the third door 17 can be arranged at a substantially midstream position of the bypass passage 16, as shown in FIG. 17. Also in the example embodiments shown in FIGS. 13 and 15, the position of the third door 17 can be arranged as shown in FIGS. 16 and 17.

Further, the bypass passage 16 can be formed in a different configuration as long as it allows the air to bypass the first heat exchanger 10. For example, the bypass passage 16 can be formed on a side of the second passage 6 so that the air bypasses the second heat exchanger 11. In this case, the air is introduced to the first outlet port 13 from the bypass passage through a duct.

In the above example embodiments, the Peltier element 8 is not energized, that is, the electric current to the Peltier element 8 is zero in the draft mode. Instead, the Peltier element 8 can be operated at a small duty ratio in the draft mode as long as the rate of heat exchange in the first and second heat exchangers 10, 11 in the draft mode is smaller than that in the normal mode.

In the first example embodiment, the seat temperature Ts detected by the seat temperature sensor 34 is used as a physical value relating to the temperature of the seat surface. In the second example embodiment, the inside temperature Tr detected by the inside air temperature sensor 33 is used as the physical value relating to the temperature of the seat surface. However, the temperature of the seat surface can be obtained in a different way.

For example, the temperature of the seat surface can be estimated by correcting the inside temperature Tr with one of the quantity of solar radiation, the outside temperature, a temperature of heat exchange that is detected by a sensor provided downstream of the heat exchanger unit 9. Alternatively, the temperature of the seat surface can be estimated based on the outside temperature, the quantity of solar radiation, and a cumulative time thereof. Further, the temperature of the seat surface can be estimated based on the quantity of solar radiation, the outside temperature, and the temperature of heat exchange.

In the above example embodiments, the first, second and third doors 12, 15, 17 are operated by the door motor 31 through the links 32, 32a, 32b. However, the structure of the doors 12, 15, 17 are not limited to the illustrated example embodiments. For example, the second door 15 of the third and fifth example embodiments can be formed of a material that is deformable according to an ambient temperature, e.g., bimetal or shape memory alloy.

In such a case, when the temperature of air passing through the first heat exchanger 10 reduces in a condition that the Peltier element 8 is energized, the second door 15 opens the second passage 6 so that the air is discharged. When the ambient temperature is relatively high in a condition that the Peltier element 8 is not energized, the second door 15 closes the second passage 6. Therefore, power used to operate the second door 15 reduces.

In the above example embodiments, it is mainly described about the cooling down operation for immediately cooling the temperature of the seat surface, for example when the seat temperature Ts is very high in summer. The above described example embodiments can be used to perform warming up operation for heating the seat surface. In this case, the electric current is supplied to the Peltier element 8 in an opposite direction. Thus, the heat absorbing side and the heat radiating side of the heat exchanger unit 9 are reversed.

For example, when the temperature of the seat surface is low in winter, the first door 12 in FIG. 1 is operated to close the inlet of the second heat exchanger 11 so that the volume of air blown from the first outlet port 13 increases. In this case, the Peltier element 8 is not energized. Thus, the air blown from the first outlet port 13 by the operation of the blower unit 4 has a temperature higher than the temperature of the cold seat surface. Accordingly, the seat surface is warmed.

Further, when the temperature of the seat surface approaches the inside temperature, the operation mode is switched from the draft mode to the normal mode. The electric current is supplied to the Peltire element 8 so that the Peltier element 8 has the heat radiating surface on the side of the first heat exchanger 10 and the heat absorbing surface on the side of the second heat exchanger 11. Also, the first door 12 is operated to open the inlet of the second heat exchanger 11. Thus, the air heated through the first heat exchanger 10 is introduced to the first outlet port 13 through the first passage 5 and is blown from the seat openings 24. The air cooled through the second heat exchanger 11 is introduced to the second outlet port 14 through the second passage 6 and is discharged to the outside of the seat 20.

In the above example embodiments, the blower unit 4 is operated at the maximum level in the draft mode. Here, the maximum level is determined within a maximum level in an actual use condition satisfying the quality in view of the performance and reducing vibration and noise.

The example embodiments of the present invention are described above. However, the present invention is not limited to the above example embodiments, but may be implemented in other ways without departing from the spirit of the invention.

Claims

1. An air conditioning unit for a seat for blowing air from a seat surface, comprising: a duct defining an inlet port and a passage space through which air introduced in the inlet port flows, the passage space separating into a first passage and a second passage, the first passage defining a first outlet port through which air is blown to the seat surface, and the second passage defining a second outlet port through which air is discharged; a heat exchanger unit disposed between the inlet port and the first and second outlet ports in the duct, the heat exchanger unit having a thermoelectric effect element, a first heat exchanger, and a second heat exchanger, the thermoelectric effect element including a first side and a second side, one of the first side and the second side radiating heat and the other one of the first side and the second side absorbing heat according to a flow direction of an electric current therein, the first heat exchanger disposed adjacent to the first side for performing heat exchange with air flowing in the first passage, and a second heat exchanger disposed adjacent to the second side for performing heat exchange with air flowing in the second passage; and an air volume control device disposed in the duct for changing a ratio of air introduced to the first outlet port to the air introduced in the inlet port between a normal mode and a draft mode, wherein in the normal mode the thermoelectric effect element is energized and the air volume control device is operated such that air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is introduced to and discharged from the second outlet port, and in the draft mode the air volume control device is operated so that the ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode, wherein in a predetermined condition, the air volume control device is operated in the draft mode and an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate in the first and second heat exchangers is smaller than that in the normal mode.

2. The air conditioning unit according to claim 1, further comprising: a blower unit disposed upstream of the inlet port of the duct for producing a flow of air into the inlet port.

3. The air conditioning unit according to claim 2, wherein in the draft mode, the blower unit is operated at a maximum level.

4. The air conditioning unit according to claim 1, wherein the predetermined condition is satisfied when a physical value relating to a temperature of the seat surface is equal to or higher than a first predetermined value.

5. The air conditioning unit according to claim 4, wherein when the physical value is lower than the first predetermined value, the thermoelectric effect element is energized in a condition same as the normal mode, and when the physical value is lower than a second predetermined value that is lower than the first predetermined value, the air volume control device is operated in the normal mode.

6. The air conditioning unit according to claim 4, wherein when the physical value is lower than the first predetermined value, the thermoelectric effect element is energized in a condition same as the normal mode, and when a first predetermined time period has elapsed since the thermoelectric effect element was energized in the condition same as the normal mode, the air volume control device is operated in the normal mode.

7. The air conditioning unit according to claim 4, wherein when the physical value is lower than the first predetermined value, the air volume control device is operated in the normal mode, and the thermoelectric effect element is energized in a condition same as the normal mode.

8. The air conditioning unit according to claim 4, wherein when the physical value reduces below a third predetermined value that is lower than the first predetermined value in a condition that the air volume control device is operated in the draft mode and the electric current supply to the thermoelectric effect element is controlled such that the heat exchange rate is smaller than that of the normal mode, the air volume control device is operated in the normal mode and the thermoelectric effect element is energized in a condition same as the normal mode.

9. The air conditioning unit according to claim 4, wherein when a second predetermined time period has elapsed since the air volume control device was operated in the draft mode and the electric current supply to the thermoelectric effect element was controlled such that the heat exchange rate is smaller than that of the normal mode in a condition that the physical value is equal to or higher than the first predetermined value, the air volume control device is operated to the normal mode and the thermoelectric effect element is energized in a condition same as that in the normal mode.

10. The air conditioning unit according to claim 1, wherein the air volume control device includes a first open and close member, the first open and close member is disposed at a position upstream of the second heat exchanger to open and close the second passage to thereby control a volume of air introduced to the second outlet port, and in the draft mode the first open and close member is operated to fully close the second passage to restrict the air from flowing to the second outlet port, to thereby increase a volume of air introduced to the first outlet port.

11. The air conditioning unit according to claim 1, wherein the air volume control device includes a first open and close member, the first open and close member is disposed to open and close the second passage at a position downstream of the second heat exchanger, when the first open and close member fully closes the second passage the air passing through the second heat exchanger is allowed to flow in the first passage, and when the first open and close member opens the second passage the air passing through the second heat exchanger is restricted from flowing in the first passage, and in the draft mode the first open and close member is disposed to fully close the second passage to increase a volume of air introduced to the first outlet port.

12. The air conditioning unit according to claim 11, wherein the first open and close member is formed of a material that deforms according to an ambient temperature and the second passage is open and closed according to deformation of the first open and close member.

13. The air conditioning unit according to claim 1, wherein the duct further defines a bypass passage through which air flows toward the first outlet port while bypassing the first heat exchanger and the second heat exchanger, the air volume control device includes a second open and close member disposed to open and close the bypass passage, and in the draft mode the second open and close member is operated to open the bypass passage so that a volume of air introduced to the first outlet port increases.

14. The air conditioning unit according to claim 13, wherein the second open and close member is disposed at a position upstream of the bypass passage.

15. The air conditioning unit according to claim 13, wherein the first heat exchanger defines an opening that opens to the bypass passage.

16. An air conditioning unit for a seat for blowing air from a seat surface, comprising: a duct defining an inlet port and a passage space through which air introduced in the inlet port flows, the passage space separating into a first passage and a second passage, the first passage defining a first outlet port through which air is blown to the seat surface, the second passage defining a second outlet port through which air is discharged, the duct further defining a bypass passage that diverges from the passage space and communicates with the first outlet port of the first passage; a heat exchanger unit disposed between the inlet port and the first and second outlet ports in the duct, the heat exchanger unit having a thermoelectric effect element, a first heat exchanger, and a second heat exchanger, the thermoelectric effect element having a first side and a second side, one of the first side and the second side radiating heat and the other one of the first side and the second side absorbing heat according to a flow direction of an electric current in the thermoelectric effect element, the first heat exchanger disposed adjacent to the first side for performing heat exchange with air passing through the first passage, the second heat exchanger disposed adjacent to the second side for performing heat exchange with air passing through the second passage; and an air volume control device disposed in the duct for changing a volume of air flowing in the bypass passage between a normal mode and a draft mode, wherein in the normal mode the thermoelectric effect element is energized and air passing through the first heat exchanger is introduced to the first outlet port and air passing through the second heat exchanger is discharged from the second outlet port, and in the draft mode a ratio of air introduced to the first outlet port to the air introduced in the inlet port is larger than that in the normal mode, wherein in the draft mode the air volume control device is operated so that a volume of air flowing through the bypass passage toward the first outlet port is larger than that in the normal mode.

17. The air conditioning unit according to claim 16, further comprising: a blower unit disposed at a position upstream of the inlet port of the duct for producing a flow of air into the inlet port.

18. The air conditioning unit according to claim 16, wherein the bypass passage is located between the seat and the first heat exchanger, in the first passage.

19. The air conditioning unit according to claim 16, wherein in the draft mode an electric current supply to the thermoelectric effect element is controlled such that a heat exchange rate of the first and second heat exchangers is smaller than that in the normal mode.

20. The air conditioning unit according to claim 16, further comprising: a first open and close member disposed upstream of the second heat exchanger, wherein the first open and close member is operated to open and close the second passage for controlling a volume of air introduced to the second outlet port, and in the draft mode the first open and close member is operated to fully close the second passage.

21. The air conditioning unit according to claim 16, further comprising: a first open and close member disposed downstream of the second heat exchanger to open and close the second passage, wherein when the first open and close member fully closes the second passage the air passing through the second heat exchanger is allowed to flow in the first passage and is restricted from flowing to the second outlet port, when the first open and close member opens the second passage the air passing through the second heat exchanger is restricted from flowing in the first passage, and in the draft mode the first open and close member is disposed to fully close the second passage.

22. The air conditioning unit according to claim 21, wherein the first open and close member is formed of a material that deforms according to an ambient temperature, and the second passage is open and closed according to deformation of the first open and close member.

23. The air conditioning unit according to claim 16, wherein the air volume control device includes a second open and close member disposed to open and close the bypass passage, and in the draft mode, the second open and close member is operated to open the bypass passage so that a volume of air introduced to the first outlet port increases.

24. The air conditioning unit according to claim 23, wherein the second open and close member is disposed upstream of the bypass passage.

25. The air conditioning unit according to claim 16, wherein the first heat exchanger forms an opening that opens to the bypass passage.