JP2002130847A - Liquid constant-temperature apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid constant-temperature device that can be prevented from becoming unusable. SOLUTION: A heat exchanger 16 is constituted to cool a liquid to be cooled by performing heat exchange between the liquid and a refrigerant. A temperature sensor 11b is constituted to detect the state of the refrigerant passed through the heat exchanger 16. A compressor 15 is constituted to compress the refrigerant. A fan motor 23 is constituted to cool the compressed refrigerant. A control computer 17 is constituted to control the number of revolutions of the fan motor 23 based on the detected value of the sensor 11b. Consequently, the refrigerant is maintained at a temperature higher than the freezing temperature T1 of the liquid to be cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid thermostat.

[0002]

2. Description of the Related Art Conventionally, there has been known a liquid thermostat for cooling a liquid to be cooled supplied to a machine tool or the like.

For example, a liquid thermostat 41 shown in FIG.
A heat exchanger 42, a detecting unit 43, a compression unit 46, a fan motor 47 and a control unit 48 are provided. Heat exchanger 42
Is designed to cool the liquid to be cooled by performing heat exchange with a refrigerant. The detecting means 43 detects the state of the refrigerant that has passed through the heat exchanger 42. The compression means 46 compresses the refrigerant.
The fan motor 47 cools the compressed refrigerant. The control means 48 performs predetermined control based on the detection value from the detection means 45 so as to keep the temperature of the liquid to be cooled constant. This control means 4
Reference numeral 8 indicates that the operation of the liquid thermostat 41 is automatically stopped based on the detection value from the detection means 43 to stop the cooling of the refrigerant. This prevents the cooled liquid to be cooled from freezing.

[0004] Some liquid thermostats 41 have an evaporation pressure adjusting valve 51 (hot gas bypass system) as shown in FIG. The evaporating pressure regulating valve 51 prevents the liquid to be cooled from freezing by flowing warm refrigerant from the compression means 46 into the vicinity of the inlet 42a of the heat exchanger 42.

[0005]

By the way, the liquid thermostat 41 shown in FIG. 5 requires an evaporation pressure regulating valve 51. As a result, there is a case where the liquid thermostat 41 becomes unusable due to failure of a movable part such as the evaporation pressure regulating valve 51. Further, since the refrigerant could not flow smoothly into the evaporating pressure regulating valve 51, there was also a problem that the flow noise of the refrigerant increased.
Further, when the size of the liquid thermostat 41 was increased, the size of the evaporation pressure regulating valve 51 also had to be increased.
In some cases, the cost for fabricating No. 1 increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a liquid thermostat capable of preventing an unusable state. A second object is to provide a liquid thermostat that can reduce the flow noise of the refrigerant. A third object is to provide a liquid thermostat that can reduce the manufacturing cost.

[0007]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, there is provided a heat exchanger for cooling a liquid to be cooled by performing heat exchange with a refrigerant. Detecting means for detecting the state of the refrigerant that has passed through the heat exchanger, compression means for compressing the refrigerant, a fan motor for cooling the refrigerant in a compressed state, and a detection value from the detecting means And a control means for performing predetermined control so as to keep the temperature of the liquid to be cooled constant. In the liquid constant temperature apparatus, the control means controls the rotation speed of the fan motor to cool the refrigerant. The gist of the invention is that the liquid is maintained at a temperature higher than the freezing temperature of the liquid.

According to a second aspect of the present invention, in the first aspect, the detecting means is a temperature sensor for measuring a temperature of the refrigerant. Hereinafter, the “action” of the present invention will be described.

According to the first aspect of the present invention, there is no movable part in the liquid thermostat. Therefore, it is possible to prevent the liquid thermostat from becoming unusable due to the failure of the movable part. Further, the flow noise of the refrigerant can be reduced. Further, the cost for manufacturing the liquid thermostat can be reduced.

According to the second aspect of the present invention, it is possible to determine whether or not the refrigerant has dropped to the freezing temperature of the liquid to be cooled by measuring the temperature of the refrigerant with the temperature sensor. Therefore, the temperature of the refrigerant can be controlled more reliably.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 and 2 show a first embodiment in which the present invention is embodied in a liquid thermostat.
This will be described in detail based on FIG.

As shown in FIG. 1, the liquid thermostat 5 is connected to a liquid tank (not shown) via pipes 6 and 7 for guiding a liquid to be cooled. The liquid to be cooled is introduced into the pipe 7 by a pump (not shown), and returns to the liquid tank via the pipe 6. The liquid to be cooled is sent to the machine tool by a pump (not shown) different from the above, and circulates through the machine tool. At that time, the heat generated from the machine tool is removed by the liquid to be cooled, and the machine tool is maintained at a constant temperature. When the temperature of the liquid to be cooled rises, the liquid to be cooled is cooled by the liquid thermostat 5 via the pipe 7 so that the liquid temperature is kept constant.

Further, as shown in FIG.
Is equipped with a heat exchanger 16, a cooling means 12, and a control computer 17 as a control means. In the heat exchanger 16, a first path 16a through which the mist-like refrigerant circulates, and a second path 1 through which the liquid to be cooled circulates separately from the first path 16a
6b are formed. The inlet side of the second path 16 b is connected to the pipe 7, and the outlet side is connected to the pipe 6. The heat exchanger 16 cools the liquid to be cooled by performing heat exchange with the refrigerant. Specifically, the liquid to be cooled from the water tank flows into the second path 16b, and is then guided again to the water tank. The liquid to be cooled is in the second path 16b.
, The heat of the liquid to be cooled is transferred to the mist-like refrigerant by the heat exchange action of the heat exchanger 16.

The cooling means 12 includes a refrigerant flow path 21, a capillary tube 26, a filter 27, a high pressure switch 28, a condenser 22, a compressor 15 as a compression means, and a fan motor 23.

The capillary tube 26 is provided on the coolant channel 21. The capillary tube 26 rapidly cools the refrigerant by expanding the refrigerant in a compressed state. The filter 27 is disposed immediately upstream of the capillary tube 26 in the refrigerant channel 21. The high pressure switch 28 is connected to the refrigerant passage 2
1 is disposed immediately upstream of the filter 27. When the pressure of the refrigerant flowing through the refrigerant channel 21 becomes too high, the high-pressure switch 28
To stop. The condenser 22 is disposed immediately upstream of the high-pressure switch 28 in the refrigerant flow path 21. The condenser 22 condenses the compressed refrigerant. The compressor 15 is connected to the refrigerant passage 2
1 is disposed immediately upstream of the condenser 22. The compressor 15 compresses the refrigerant. The fan motor 23 is not located on the coolant flow path 21, but is arranged near the condenser 22. In the present embodiment, the rotation speed of the fan motor 23 is controlled by a frequency inverter. The fan motor 23 cools the condensed refrigerant and liquefies the refrigerant. That is, the condenser 22 in the present embodiment is of an air-cooled type.

In the liquid thermostat 5, the refrigerant that has passed through the first path 16a of the heat exchanger 16 is in a low-pressure gaseous state because it takes away the heat of the liquid to be cooled. This gaseous refrigerant flows into the compressor 15, where it is compressed. Most of the compressed gaseous refrigerant is supplied to the condenser 22 as it is.
Flows into. The outer surface of the condenser 22 is blown by the rotation of the fan motor 23. By controlling the rotation speed of the fan motor 23, the temperature of the refrigerant is maintained at a temperature equal to or higher than the freezing temperature T1 of the liquid to be cooled, and the liquid to be cooled is prevented from freezing.

As shown in FIG. 1, inside the liquid thermostat 5, specifically, on the refrigerant flow path 21, two temperature sensors 11b as detecting means are provided. These temperature sensors 11b are disposed immediately downstream of the heat exchanger 16 in the refrigerant flow path 21. Temperature sensor 11b
Is designed to measure the temperature of the refrigerant passing through the heat exchanger 16. On the other hand, a temperature sensor 11 c for detecting the temperature of the liquid to be cooled is provided on the pipe 7. By controlling the compressor 15 so as to keep the temperature detected by the temperature sensor 11c constant, the liquid to be cooled is maintained at the target temperature. These temperature sensors 1
1b and 11c always output a predetermined detection value to the control computer 17.

The control computer 17 includes a temperature follower, a memory, and the like. The detection value detected by the temperature sensor 11b is taken into the control computer 17 according to a predetermined control program stored in the memory. And the control computer 1
Reference numeral 7 performs predetermined control based on the detection value of the temperature sensor 11b so as to maintain the temperature of the refrigerant at or above the freezing temperature of the liquid to be cooled.

As shown in FIG. 2, when the temperature of the refrigerant is higher than the freezing temperature T1 of the liquid to be cooled, the temperature follower controls the fan motor 23 to increase the rotation speed and lower the temperature of the refrigerant. Do. When the temperature of the refrigerant is considerably higher than the freezing temperature T1, the temperature following means keeps the fan motor 23 at the highest rotational speed based on the detected value (range A3 shown in FIG. 2). . Then, when the temperature of the refrigerant approaches the freezing temperature T1 of the liquid to be cooled, control is performed to gradually decrease the rotation speed of the fan motor 23 in proportion to the detected value (range A1 shown in FIG. 2). Further, when the temperature of the liquid to be cooled becomes substantially the same as the freezing temperature T1, the temperature following means stops the fan motor 23 (range A2 shown in FIG. 2). As a result, the temperature of the refrigerant is maintained at a temperature higher than the freezing temperature T1 of the liquid to be cooled, and the liquid to be cooled is prevented from freezing.

Therefore, according to the first embodiment, the following effects can be obtained. (1) In the refrigerant channel 21 in the first embodiment, the evaporation pressure adjusting valve 51 which is conventionally required does not exist. Therefore, it is possible to prevent the liquid thermostat 5 from becoming unusable due to a failure of a movable part such as the evaporation pressure adjusting valve 51. Further, since the evaporation pressure adjusting valve 51 does not exist, the refrigerant flows smoothly in the refrigerant channel 21. Therefore, the flow noise of the refrigerant can be reduced. Further, as in the prior art, the liquid thermostat 5
It is not necessary to increase the size of the evaporation pressure regulating valve 51 even if the size of the liquid thermostat increases, so that the cost for manufacturing the liquid thermostat 5 can be reduced.

(2) The temperature of the refrigerant is the freezing temperature T of the liquid to be cooled.
It is held at one or more. Therefore, even when the liquid to be cooled is partially blocked in the liquid thermostat 5, freezing of the liquid to be cooled can be reliably prevented.

(3) By measuring the temperature of the refrigerant flowing in the refrigerant flow path 21 with the temperature sensor 11b, it is possible to determine whether the refrigerant has dropped to the freezing temperature T1 of the liquid to be cooled. Therefore, the temperature of the refrigerant can be controlled more reliably.

(4) The temperature follower provided in the control computer 17 controls the rotation speed of the fan motor 23 in proportion to the value detected by the temperature sensor 11b. Therefore, the control of the refrigerant by the temperature following means
This is performed before approaching the freezing temperature T1. Therefore, the temperature of the refrigerant can be controlled more reliably.

(5) When the temperature of the liquid to be cooled becomes substantially the same as the freezing temperature T1, the temperature follow-up means provided in the control computer 17 uses the fan motor 2 based on the detected value.
3 is stopped. Therefore, it is possible to more reliably prevent the liquid to be cooled from freezing.
Further, by stopping the rotation of the fan motor 23 within the range A2, it is possible to prevent power consumption from being wasted.

(6) The temperature sensor 11b
Are arranged in two places. Therefore, the temperature of the refrigerant can be measured more accurately. (7) The coolant is maintained at a temperature higher than the freezing temperature T1 of the liquid to be cooled by controlling the rotation speed of the fan motor 23 by the temperature following means provided in the control computer 17. Therefore, the liquid to be cooled is prevented from being frozen in the heat exchanger 16. Therefore, the liquid to be cooled is also prevented from being partially frozen in the heat exchanger 16. Therefore, the liquid to be cooled does not expand in the heat exchanger 16 due to the freezing of the liquid to be cooled. Therefore, it is possible to prevent the heat exchanger 16 from being damaged due to the partial cooling of the liquid to be cooled. (Second Embodiment) Next, a second embodiment in which the present invention is embodied in a dehumidifier will be described with reference to FIG. Here the first
The differences from the embodiment will be mainly described, and the common points will be denoted by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 3, the dehumidifier 31 includes a heat exchanger 16, a cooling means 12, and a control computer 17 as control means. The dehumidifying device 31 performs dehumidification by cooling the gas to be cooled by the heat exchanger 16.

The pipe 7 for supplying the gas to be cooled and the pipe 6 for discharging the gas to be cooled are connected to the second path 16b in the heat exchanger 16. The gas to be cooled passing through the second path 16b is cooled by performing heat exchange with the refrigerant passing through the first path 16a. The heat exchanger 16 is provided with a drain outlet 16c. The drain outlet 16c discharges dew generated by cooling the gas to be cooled to the outside.

The control computer 17 includes the temperature sensor 11
Based on the detected value of b, predetermined control is performed to keep the cooled gas constant. When the temperature of the refrigerant is higher than the freezing temperature of the dew, the temperature following means constituting the control computer 17 performs control such that the rotation speed of the fan motor 23 is increased to lower the temperature of the refrigerant. When the temperature of the refrigerant is considerably higher than the freezing temperature of the dew, the temperature following means keeps the rotation speed of the fan motor 23 at the highest based on the detected value. When the temperature of the refrigerant approaches the freezing temperature of the dew, the fan motor 23
Is controlled so as to gradually decrease the number of rotations in proportion to the detected value. Further, when the temperature of the refrigerant becomes substantially the same as the freezing temperature of the dew, the temperature follow-up means
To stop. As a result, the temperature of the refrigerant is maintained at a temperature higher than the dew temperature. for that reason,
The dew generated from the gas to be cooled is prevented from freezing.

Therefore, according to the second embodiment, the following effects can be obtained. (8) The temperature of the refrigerant is maintained at a temperature equal to or higher than the dew temperature. Therefore, the dew generated from the gas to be cooled is prevented from being frozen in the heat exchanger 16. Therefore, it is possible to prevent the dew from being unable to be discharged from the drain discharge port 16c.

The first and second embodiments may be modified as follows. -In the said 1st and 2nd embodiment, you may increase the number of the temperature sensors 11b arrange | positioned at the refrigerant flow path 21. With this configuration, the temperature of the refrigerant can be more accurately measured as the number of the temperature sensors 11b is increased.
Note that the number of the temperature sensors 11b may be reduced. Further, the temperature sensor 11b may be installed in another place on the downstream side of the heat exchanger 16.

In the first and second embodiments, the detecting means for measuring the state of the refrigerant is the temperature sensor 11b.
However, the state of the refrigerant may be measured using another sensor such as a pressure sensor as the detection unit.

The number of the temperature sensors 11c to be installed depends on the first
The invention is not limited to only those described in the embodiment, and may be two or more. The temperature sensor 11c
May be changed.

In the first embodiment, in the range A3, the temperature follow-up means uses the fan motor 2 based on the detected value.
3 was maintained at the highest speed. Instead, in the range A3, the temperature follower may control the rotational speed of the fan motor 23 in proportion to the detected value. That is, the control of the temperature following means in the range A3 may be the same as the control in the range A1.

In the first embodiment, in the range A2, the temperature follow-up means uses the fan motor 2 based on the detected value.
3 was stopped. Instead, in the range A2, the temperature follower may control the rotation speed of the fan motor 23 in proportion to the detected value. That is, the control of the temperature following means in the range A2 is
The same control as in the case of 1 may be performed.

In the first embodiment, in the range A1, the temperature follower controls the rotation speed of the fan motor 23 in proportion to the detected value. However, the temperature following means controls the fan motor 23 to rotate, stop, or control the number of rotations, depending on the degree of change in the detected value.
For example, PID control, fuzzy control, or the like may be performed.

In the first and second embodiments, the rotation speed of the fan motor 23 is controlled by the frequency inverter. However, the rotation speed of the fan motor 23 may be controlled by other means such as a thyristor and a solid state relay.

In the liquid thermostat 5 of the first embodiment, the air-cooled condenser 22 for cooling the refrigerant by the fan motor 23 is used. Instead,
A water-cooled condenser 22 that cools the refrigerant with the cooling water by adding a flow path through which the cooling water passes in the condenser 22
May be used. With this configuration, the refrigerant can be cooled more reliably. Further, by controlling the amount of the cooling water, the temperature of the refrigerant can be controlled.

In the first and second embodiments, the control of the temperature of the refrigerant is performed by controlling the number of revolutions of the fan motor 23. Instead, the refrigerant flow path 21
An electric heater may be arranged on the upper side, and the temperature of the refrigerant may be controlled by heating the refrigerant with the electric heater.

The liquid thermostat 5 of the first embodiment comprises:
It may be used for any machine tool (for example, an electric discharge machine, a polishing system, a drilling system, etc.), and may be used for other than machine tools.

The dehumidifier 31 of the second embodiment may be used for any type of cooling device (for example, an air conditioner, a dryer, etc.), and may be used for devices other than the cooling device.

In the first embodiment, the liquid to be cooled may be water or compressed air. Next, in addition to the technical ideas described in the claims, technical ideas grasped by the above-described embodiments will be listed below.

(1) The liquid thermostat according to claim 1 or 2, wherein the control means controls the number of revolutions of the fan motor in proportion to the detected value. Therefore, according to the technical idea (1), the temperature of the refrigerant can be more reliably controlled.

(2) The liquid constant temperature apparatus according to (1) or (2), wherein the control means stops the fan motor based on the detected value. Therefore, according to the technical idea (2), it is possible to more reliably prevent the liquid to be cooled from freezing. Further, power consumption required for rotating the fan motor can be reduced.

(3) In the first or second aspect, the technical concept (1) or (2), the control means may maintain the rotational speed of the fan motor at the highest level based on the detected value. A liquid thermostat characterized by the above.

(4) The liquid thermostat according to claim 2, wherein the temperature sensors are provided at a plurality of locations. Therefore, according to the technical idea (4), the temperature of the refrigerant can be measured more accurately.

(5) A heat exchanger for cooling the gas to be cooled by exchanging heat with the refrigerant, detecting means for detecting the state of the refrigerant passing through the heat exchanger, and compressing the refrigerant. Compression means, a condensing means for cooling the compressed refrigerant sent from the compression means and condensing it into a liquid refrigerant, a fan motor for cooling the refrigerant in a compressed state, and based on a detection value from the detection means. Control means for performing predetermined control to keep the temperature of the gas to be cooled constant, wherein the dehumidifier cools the gas to be cooled by the heat exchanger and dehumidifies the gas. A dehumidifier, wherein the refrigerant is maintained at a temperature higher than a freezing temperature of dew caused by cooling the gas to be cooled by controlling a rotation speed of the refrigerant.

(6) In the technical idea (5), the detecting means is a temperature sensor for measuring the temperature of the refrigerant.

[0048]

As described above in detail, according to the first aspect of the present invention, it is possible to prevent the liquid thermostat from becoming unusable. Further, the flow noise of the refrigerant can be reduced. Further, the cost for manufacturing the liquid thermostat can be reduced.

According to the second aspect of the present invention, the temperature of the refrigerant can be controlled more reliably.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a liquid thermostat in a first embodiment.

FIG. 2 is a graph showing an operation state of a fan motor.

FIG. 3 is a schematic diagram showing a dehumidifying device according to a second embodiment.

FIG. 4 is a schematic view showing a liquid thermostat according to the related art.

FIG. 5 is a schematic view showing a liquid thermostat according to the related art.

[Explanation of symbols]

5: liquid thermostat, 11b: temperature sensor as detecting means, 15: compressor as compressing means, 16: heat exchanger,
17: control computer as control means, 23: fan motor, T1: freezing temperature.

Claims (2)

[Claims] 1. A heat exchanger for cooling a liquid to be cooled by exchanging heat with a refrigerant, a detecting means for detecting a state of the refrigerant passing through the heat exchanger, and compressing the refrigerant. Compression means, a fan motor for cooling the refrigerant in a compressed state, based on a detection value from the detection means,
A liquid constant temperature apparatus comprising: a control unit that performs predetermined control so as to keep the temperature of the liquid to be cooled constant. The control unit controls the number of revolutions of the fan motor so that the refrigerant is cooled by the liquid to be cooled. A liquid thermostat characterized by being maintained at a temperature higher than the freezing temperature of the liquid. 2. The liquid thermostat according to claim 1, wherein said detecting means is a temperature sensor for measuring a temperature of said refrigerant.