JP2003028768A - Electronic cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic cooling device efficiently operable even when a using environmental temperature has a large width, and inexpensively and rationally operable for a long period without using a large-capacity control transistor, capable of exhibiting a desired cooling power. SOLUTION: In this electronic cooling device, a heat exchange block 1 is installed on one side of a Peltier element 2 driven by a constant-current circuit 25, and a radiator 3 is installed on the other side thereof, and the radiator 3 is air-cooled by a fan 12. In the device, a voltage between a cooling-side terminal and a heating-side terminal of the Peltier element 2 is detected, and the driving power for the fan 12 is changed based on the voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic cooling device used for cooling a gas supplied to a gas analysis section of a gas analyzer, for example.

[0002]

2. Description of the Related Art When analyzing a specific component contained in a factory exhaust gas or the atmosphere, if a sample gas used for the analysis contains water, various adverse effects are exerted on a detection device. It is necessary to remove water beforehand. As a device for removing water in sample gas, there is an electronic cooling device that has the function of cooling the sample gas and condensing the water contained in the sample gas to separate it as a drain. The heat exchange block is cooled by a Peltier element. This Peltier element supplies a current to the two electrodes, and the energy transfers heat between the electrodes, one electrode side is cooled, the other electrode side generates heat, and the cooling capacity is exerted on the cooling side. It was done so.

However, in the Peltier element, when the ambient temperature rises high and the temperature difference between the two electrodes becomes large, the function of creating the temperature difference and the heat conduction inside the Peltier element caused by this temperature difference are antagonized with each other. As a result, the temperature difference is reached at which the cooling capacity is not exerted. FIG. 7 shows this.
That is, FIG. 7 shows a change with time in temperature when the Peltier element is energized. In this figure, reference symbol A represents a temperature change on the heat (high temperature) side of the Peltier device, and reference symbol B represents the Peltier device. It is a curve showing the temperature change on the cooling (low temperature) side. When the ambient temperature of the Peltier element is low, the temperature difference between the heat generating side and the cooling side is small and the cooling efficiency is large, but when the ambient temperature is high, the temperature difference is large, and the temperature difference of 50 ° C or more (in the figure, (Indicated by the symbol C) of 0) occurs, the cooling efficiency becomes zero.

Therefore, in order to maintain a predetermined cooling temperature even if the ambient temperature rises, it is necessary to cool the heat generating side. Therefore, conventionally, a radiator provided with a radiation fin on the heat generation side of the Peltier element was provided, and in order to reduce the thermal resistance of the radiation fin, a fan was provided to blow air to the radiator. If the operating environment temperature of the electronic cooling device is widely required, set the radiator and fan capacities so that they can be adequately handled even under a wide range of temperature and severe temperature conditions, and ensure reliability. I was doing.

[0005]

However, as described above, when the capacities of the radiator and the fan are set so as to sufficiently cope with a wide range of temperatures and severe temperature conditions, under normal use environment, The heat dissipation capacity and the ventilation capacity of the radiator and fan are too large, which increases the cost.

By the way, the Peltier element used in the electronic cooling device is generally controlled by a constant current. However, when the potential difference between the electrodes on the heat generating side and the cooling side becomes large, a power supply voltage corresponding to it is prepared and the constant current is adjusted. It needs to be designed so that the supply is performed normally. When the environmental temperature becomes low, the temperature difference between the electrodes can be small even when controlling at the same cooling temperature, so the voltage between the electrodes becomes small even if the current required for cooling is the same. Therefore, the collector-emitter voltage of the control transistor used in the constant current circuit has a large difference between when the environment temperature is low and when it is high, and by design, the collector-emitter voltage is large in a low temperature environment. Sometimes it is necessary to choose a control transistor that does not cause power rating problems. As a result, a large-capacity control transistor is required, and the power consumption in each of the Peltier element and the control transistor increases, so that when used for a long time, the total power consumption increases and the cost increases. There's a problem.

In the Peltier element, it has been known that a thermoelectromotive force v proportional to the Peltier element temperature difference ΔT is generated between the high temperature side terminal and the low temperature side terminal. Figure 8
FIG. 4 is a diagram showing a relationship between the thermoelectromotive force v and the temperature difference ΔT.

As can be understood from FIG. 8, the voltage v is a temperature difference Δ between the high temperature side terminal and the low temperature side terminal of the Peltier element.
Increases in proportion to T. This is because the so-called Seebeck effect occurs in which the potential difference increases with the temperature difference in the Peltier element. Here, when the Seebeck coefficient is α, between the voltage v and the temperature difference ΔT,
The relationship of v = α × ΔT is established. Therefore, the temperature difference between the Peltier elements can be detected by monitoring the voltage across the Peltier element.

The present invention has been made in consideration of the above matters. A first object of the present invention is that it is possible to perform an efficient operation even in a case where a wide range of ambient temperatures is used, which is desirable. A second object of the present invention is to provide an electronic cooling device capable of exerting the cooling capacity of the electronic cooling device, and a second object thereof is an electronic cooling device which can be operated inexpensively and rationally over a long period of time without using a large-capacity control transistor. It is to provide a device.

[0010]

In order to achieve the first object, in the first invention, a heat exchange block is provided on one side of a Peltier element driven by a constant current circuit, and a radiator is provided on the other side. In an electronic cooling device in which this radiator is air-cooled by a fan, the voltage between the cooling side terminal and the heating side terminal of the Peltier element is detected, and the drive power for the fan is changed based on this voltage. I am trying to let you.

In the electronic cooling device having the above structure, the electric power having a magnitude proportional to the difference between the temperature on the cooling side of the Peltier element and the temperature on the heat generating side of the Peltier element is supplied to increase the air volume by the fan and to the radiator. By giving a predetermined amount of air flow, the heat is radiated quickly. Therefore,
With this configuration, the electronic cooling device can be efficiently operated and a desired cooling capacity can be exhibited even when the ambient temperature used has a wide range.

In order to achieve the above-mentioned second object, in the second invention, a heat exchange block is provided on one side of the Peltier element driven by the constant current circuit, and a radiator is provided on the other side. In an electronic cooling device configured to air-cool by a fan, a voltage between a cooling side terminal and a heating side terminal of the Peltier element is detected, and a drive voltage for the constant current circuit is changed based on this voltage. I have to.

In the electronic cooling device having the above structure, when the temperature of the environment in which it is installed is relatively low and the difference between the temperature on the cooling side and the temperature on the heating side of the Peltier element is small, a constant current circuit. By reducing the driving voltage for the Peltier device and the control transistor, power consumption can be suppressed. Therefore, according to this configuration, the electronic cooling device can be efficiently operated and a desired cooling capacity can be exhibited even when a wide range of ambient temperature is used.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are diagrams for explaining the first invention. First, FIG. 1 and FIG.
Shows an example of the electronic cooling device of the first invention. In these figures, 1 is a heat exchange block, which is made of, for example, a metal material having good thermal conductivity such as aluminum or duralumin, and formed into a substantially rectangular parallelepiped shape. Has been done. The Peltier element 2 cools the heat exchange block 1 and is formed in a flat plate shape. The Peltier element 2 has a protruding flat surface 1 whose one side surface is formed on one side surface of the heat exchange block 1.
It is provided so as to be in close contact with a. A radiator 3 is provided in close contact with the other side surface of the Peltier element 2, and has a plurality of radiation fins 3a. 4 is a heat exchange block 1
Further, it is a heat insulating material provided around the Peltier element 2 and is made of foamed plastic such as urethane foam. This heat insulating material 4 is covered with a cover case 5 made of aluminum or the like on five faces except for a portion in contact with the radiator 3.

Numerals 6 and 7 are independent pipes that penetrate the heat exchange block 1 and vertically penetrate the heat exchange block 1 and the heat insulating material 4 in parallel. And these tubes 6,
An opening on the one end side (upstream side) of 7 is an inlet for the sample gas to be used for the analysis, and is connected to a channel on the sample gas supply source side (not shown). Further, on the side of the tubes 6 and 7 through which the heat exchange block 1 is inserted, the tubes 8 and 9 which are independent of each other
Are connected, the pipes 6 and 8 form one sample gas processing system 10, and the pipes 7 and 9 form another sample gas processing system 11. Note that 10a and 11a are connection points, and parts 10b and 11b on the downstream side of the connection points 10a and 11a are drain discharge parts of the sample gas processing systems 10 and 11 and are connected to a drain pot (not shown). ing. The tubes 6 to 9 are made of corrosion resistant titanium.

Reference numeral 12 denotes a fan, which is held by support legs 13 and is driven by, for example, a DC power source so as to blow air toward the radiation fins 3a of the radiator 3.

As the heat insulating material 4, not only urethane foam but also various kinds of foamed plastic such as polystyrene foam may be used, and further heat insulating clay may be used.

FIG. 3 is a diagram schematically showing the electrical construction of the electronic cooling device constructed as described above. In this figure, 20 is a drive circuit for the Peltier element 2 and 30 is a fan 1.
2 is a drive circuit.

Then, the Peltier device driving circuit 20
Is a comparator 23 that compares the output of the temperature sensor 21 that measures the temperature of the heat exchange block 1 that is the object to be cooled with the output of the reference voltage output circuit 22, and this comparator 23
The temperature control temperature setting circuit 24 that sets the temperature control temperature based on the output of the temperature control circuit 24 and the constant current circuit 25 that operates based on the output of the temperature control temperature setting circuit 24. It is driven by the output current of the circuit 25. The reference voltage output circuit 22 is configured to output based on the output of the controlled temperature setting circuit 24. A voltage detection circuit 26 detects the difference between the temperature on the cooling side 2a and the temperature on the heat generating side 2b of the Peltier element 2 based on the difference between the voltages, and a voltage V proportional to the temperature difference in the Peltier element 2. It is configured to output _P.

The fan drive circuit 30 compares a DC power supply 31 as a drive power supply with the output voltage V _B of the DC power supply 31 and the output voltage V _p of the voltage detection circuit 26, and always uses the larger one. Output voltage comparison output circuit 32
And a DC / DC converter 33 for DC / DC converting the output of the voltage comparison output circuit 32, and the fan 12 is driven based on the output voltage of the DC / DC converter 33. In the electronic cooling device of this embodiment, the control current is turned on / on when the temperature adjustment point is reached.
Since it is repeatedly turned off, the lowest voltage required to drive the fan 12 is supplied from the DC power supply 31 side.

In the electronic cooling device having the above structure, when the temperature of the environment in which it is installed is relatively low and the difference between the temperature of the cooling side 2a and the temperature of the heat generating side 2b of the Peltier element 2 is small (normal time). ) Is the output voltage V of the voltage detection circuit 26.
_p is smaller than the output voltage V _DC of the DC power supply 31. Therefore, the output voltage V _DC of the DC power supply 31 is supplied to the DC / DC converter 33, which is appropriately DC / DC converted and supplied to the fan 12. Thus, when the temperature difference between the cooling side 2a and the heat generating side 2b of the Peltier element 2 is small, the fan 12 is driven by the voltage (electric power) based on the output of the DC power supply 31. At this time, the amount of air blown to the radiator 3 by the fan 12 is constant, and the radiator 3 radiates a predetermined amount of heat.

When the ambient temperature rises and the difference between the temperature on the cooling side 2a and the temperature on the heat generating side 2b of the Peltier element 2 increases, the output voltage V _p of the voltage detection circuit 26 becomes D
It becomes larger than the output voltage V _DC of the C power supply 31. Therefore, the DC / DC converter 33 includes the voltage detection circuit 26.
The supply output voltage V _p, which is supplied is appropriately converted DC / DC fan 12. In this way, when the temperature difference between the cooling side 2a and the heat generating side 2b of the Peltier element 2 becomes large, the fan 12 is driven by the voltage (electric power) based on the output of the output voltage V _p of the voltage detection circuit 26, and this voltage ( Since the electric power) is larger than the voltage (electric power) based on the output of the DC power supply 31 in the normal state, the amount of air blown from the fan 12 to the radiator 3 is stronger and the radiator 3
The heat radiation in is promptly performed. In this case, if the supply voltage to the fan 12 is increased in proportion to the temperature difference, the air volume can be controlled more reliably.

As described above, in the electronic cooling device of the first aspect of the invention, the cooling side 2a and the heat generating side 2 of the Peltier element 2 are provided.
to detect the voltage (thermoelectromotive force) V between b, that is,
The thermoelectromotive force V generated in the Peltier element 2 is detected, and when the difference between the temperature of the cooling side 2a and the temperature of the heat generating side 2b of the Peltier element 2 becomes large, the supply voltage to the fan 12 is increased, Since the generated air volume can be increased, unlike the conventional electronic cooling device, it is not necessary to provide a radiator having an excessively large heat radiation capacity in a normal time or a fan having an excessively large air blowing capacity in a normal time.
It is possible to use the one having the minimum required small capacity as 2 and the radiator 3, and the cost can be reduced accordingly.

4 to 6 are views for explaining the second invention. First, FIG. 4 and FIG. 5 show an example of the electronic cooling device of the second invention. FIG. 4 is a diagram schematically showing the electrical configuration of the electronic cooling device of the second invention. The configuration shown in this figure is almost the same as the electrical configuration of the electronic cooling device of the first invention shown in FIG. The difference is that the output voltage of the DC / DC converter 33 is also supplied to the constant current circuit 25.

FIG. 5 schematically shows an example of the configuration of the constant current circuit 25 in the electronic cooling device of the second invention. As shown in this figure, the Peltier element 2 has a DC
The output voltage of the / DC converter 33 is supplied. A control transistor 34 is connected in series with the Peltier element 2, and a resistor 3 is connected to the emitter of the control transistor 34.
5 is connected. An operational amplifier 36 is connected so as to supply an output to the base of the control transistor 34. The output of the reference voltage output circuit 22 is divided by resistors 37 and 38 into one terminal (+) of this operational amplifier 36. The voltage is input, and the potential of the point 39 between the control transistor 34 and the resistor 35 is input to the other terminal (−). 40 is a transistor as a switching element whose collector is connected to a point 41 between the base of the control transistor 34 and the output side of the operational amplifier 36. The output of the temperature adjustment setting circuit 24 is input to the base of this transistor 40. It is done.

Before describing the operation of the constant current circuit 25, the configuration and operation of the constant current circuit in the conventional electronic cooling device will be described with reference to FIG. The constant current circuit 25A shown in this figure uses a DC / DC converter 33 as a power source for driving the Peltier device 2.
DC power supply 4 with fixed output voltage instead of using
The difference from the constant current circuit 25 of the second invention is that it is provided with 2.

In the constant current circuit 25A, the potential at the point 39 is V _R , the resistance value of the resistor 35 is R, and the current flowing through the Peltier element 2 and the control transistor 34 is I.
Then, the relationship V _R = IR holds.

[0028] Then, the operational amplifier 36, the V _R is such that the potential V _s at the connection point 43 of two resistors 37 and 38, that is, acts so that V _R → V _s.

Therefore, the voltage V _R is always constant (=
V _s) becomes, R is constant because it is fixed resistors, therefore, it becomes I = V _R / _R = constant current.

When the Peltier element 2 is controlled so that the temperature of the surface on the cooling side is constant, the voltage V _P between both electrodes of the Peltier element 2 changes depending on the ambient temperature. Therefore, even if the current I is constant, the voltage V _P may increase or decrease depending on the ambient temperature.

The terminal voltage V _Tr in the control transistor 34 is represented by V _Tr = V _a -V _P -V _R. Even when V _P is large, the output voltage V _{a of the} DC power supply 42 is V _a. Is constant and V _R << V _P <V _a , so that V _Tr ≈V _a −V _P.

If the output voltage V _a of the DC power supply 42 is constant, the V _Tr increases as the inter-terminal voltage V _P of the Peltier element 2 decreases.

By the way, when the voltage V _P is small, that is, when the environmental temperature is low, the constant current circuit 25A operates normally even if V _a is decreased. Therefore,
If the voltage V _a is reduced when the voltage V _P is low, the internal power consumption V _P × I of the Peltier element 2 and the power consumption of the control transistor 34 during the operation of the electronic cooling device can be reduced. .

Therefore, as a voltage to be supplied to the Peltier element 2, instead of the conventional DC power supply 42 whose output voltage is fixed, as shown in FIG. 5, a DC / DC converter 33 is used.
Is supplied to the Peltier device 2. As described in detail in the first aspect of the invention, the output voltage of the DC / DC converter 33 increases as the thermoelectromotive force V increases, that is, the environmental temperature rises and the temperature of the cooling side 2a of the Peltier element 2 and the heat generation side thereof. The wider the temperature difference between 2b and
growing. On the contrary, the smaller the thermoelectromotive force V is, that is, the smaller the temperature difference is, the smaller the output voltage of the DC / DC converter 33 is.
By supplying the output voltage of the converter 33 to the Peltier element 2, it is possible to suppress the power consumption in the Peltier element 2 and the control transistor 34.

In this way, the cooling side 2a of the Peltier element 2 is
The voltage V between the heat generating side 2b and the heat generating side 2b is detected, that is, the thermoelectromotive force V generated in the Peltier element 2 is detected, and the drive power is changed according to the temperature difference between the cooling side 2a and the heat generating side 2b. I am trying. Therefore, also in the second aspect of the present invention, the electronic cooling device can be efficiently operated and a desired cooling capacity can be exhibited at a low cost when a wide range of ambient temperatures is used.

In the electronic cooling device shown in FIG. 4, the fan 12 is also driven by the output voltage of the DC / DC converter 33. Therefore, in addition to the above-described effects, the effects of the first invention are obtained. Play.

[0037]

As described above, according to the first aspect of the invention, the heat exchange block is provided on one side of the Peltier element driven by the constant current circuit, and the radiator is provided on the other side, and the radiator is a fan. In the electronic cooling device configured to perform air cooling by means of the above, the voltage between the cooling side terminal and the heating side terminal of the Peltier element is detected, and the drive power for the fan is changed based on this voltage. , Even if the environment temperature range to be used is large, it is only necessary to provide a minimum required small capacity fan, and therefore, even when the environment temperature to be used has a wide range, the electronic cooling device can be operated efficiently. The desired cooling capacity can be exhibited.

In the second invention, a heat exchange block is provided on one side of the Peltier element driven by the constant current circuit, a radiator is provided on the other side, and the radiator is air-cooled by a fan. In the electronic cooling device, the voltage between the cooling side terminal and the heating side terminal of the Peltier element is detected, and the drive voltage for the constant current circuit is changed based on this voltage. Even when the temperature has a wide range, the electronic cooling device can be efficiently operated at low cost and the desired cooling capacity can be exhibited.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an example of an electronic cooling device of the present invention.

FIG. 2 is an exploded perspective view of the electronic cooling device.

FIG. 3 is a diagram schematically showing an example of an electrical configuration of the electronic cooling device.

FIG. 4 is a diagram schematically showing another example of the electrical configuration of the electronic cooling device.

FIG. 5 is a diagram schematically showing an example of the configuration of a constant current circuit used in the electronic cooling device.

FIG. 6 is a diagram schematically showing a general constant current circuit.

FIG. 7 is a diagram showing a change with time in temperature when a Peltier element is energized.

FIG. 8 is a diagram showing a relationship between a thermoelectromotive force and a temperature difference when a Peltier element is energized.

[Explanation of symbols]

1 ... Heat exchange block, 2 ... Peltier element, 2a ... Cooling side, 2b ... Heat generating side, 3 ... Radiator, 12 ... Fan, 25 ...
Constant current circuit.

Claims (2)

[Claims] 1. An electronic cooling device in which a heat exchange block is provided on one side of a Peltier element driven by a constant current circuit, a radiator is provided on the other side, and the radiator is air-cooled by a fan. An electronic cooling device, wherein a voltage between a cooling side terminal and a heating side terminal of the Peltier element is detected, and drive power for the fan is changed based on the voltage. 2. An electronic cooling device in which a heat exchange block is provided on one side of a Peltier element driven by a constant current circuit, a radiator is provided on the other side, and the radiator is air-cooled by a fan, An electronic cooling device, characterized in that a voltage between a cooling side terminal and a heating side terminal of the Peltier element is detected, and a drive voltage for the constant current circuit is changed based on this voltage.