JP2775089B2 - Method of preventing coolant from freezing in cooling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a cooling liquid from freezing in a cooling device for cooling a cooling object by circulating a cooling liquid cooled by a cooler to the object to be cooled by a circulation pump.

[0002]

2. Description of the Related Art In general, there is known a cooling device which circulates a cooling liquid (cooling water) cooled by a cooler (refrigerator) to a cooled object such as a machine tool by a circulation pump to cool the cooled object. Have been.

[0003] Since a large-sized cooling device is often installed outdoors, there is a problem in a cold region that the cooling liquid freezes during non-operation such as at night. The location where the cooling liquid freezes differs depending on the configuration and installation conditions of the cooling device.For example, the inside of a circulating pump formed of a metal material or the inside of a connector for connecting piping is compared with other parts. Easy to freeze.

For this reason, conventionally, a coolant or the surrounding temperature is detected by a temperature sensor, and when the detected temperature falls below a preset temperature, a circulation pump is operated to generate heat of the circulation pump and circulation of the coolant. Utilization was used to prevent the cooling liquid from freezing.

[0005]

However, the above-described conventional method for preventing freezing of the coolant has the following problems.

First, since there is a temperature difference depending on the location of the coolant, even if the temperature of the specific location is detected by the temperature sensor, there is a possibility that the coolant may freeze at a location other than the specific location. I can not plan. On the other hand, in order to surely prevent the freezing, for example, it is sufficient to set a set temperature with a certain margin, but on the other hand, the operation of the circulating pump is wasted and the economy and energy saving are impaired.

Second, since a dedicated temperature sensor and a process for assembling the temperature sensor are required, the number of parts is increased and the number of manufacturing steps is increased, resulting in an increase in cost.

The present invention has solved the above-mentioned problems in the prior art, and can reliably prevent freezing, and can improve economic efficiency and energy saving.
Moreover, it is an object of the present invention to provide a method for preventing a cooling liquid from freezing in a cooling device, which can reduce the cost.

[0009]

According to the method for preventing freezing of a coolant according to the present invention, a coolant W cooled by a cooler 2 is circulated to a cooled object 4 by a circulating pump 3 to cool the cooled object 4.
In the cooling device 1 for cooling the upper temperature Tu,
Medium temperature Tm and lower temperature Td (where Tu>Tm>
Td), the temperature of the coolant W is detected by the temperature sensor 5, and when the detected temperature Tp is equal to or lower than the upper temperature Tu and exceeds the lower temperature Td, the circulating pump 3 is stopped for the stop time tx and the operation is stopped. When the intermittent operation is performed at time ty and the detected temperature Tp becomes lower than the lower temperature Td,
The circulating pump 3 is continuously operated until the detected temperature Tp becomes the middle temperature Tm.

In this case, according to the most preferred embodiment, the temperature sensor 5 is also used as a temperature sensor used for controlling the temperature of the coolant W. The stop time tx during intermittent operation is 5-6.
At 0 minutes, the operation time ty is set to be equal to or longer than the time during which the coolant W goes through the circulation path of the coolant W. Furthermore, the upper temperature Tu during continuous operation is set to a temperature at which the coolant W does not freeze even when the circulation pump 3 is stopped, and the lower temperature T
d is set to a temperature at which the coolant W does not freeze if the circulation pump 3 is operated intermittently by the stop time tx and the operation time ty.

[0011]

According to the coolant freezing prevention method of the present invention, the temperature of the coolant W is detected by the temperature sensor 5, and the operation of the circulation pump 3 is controlled based on the detection result, that is, the detected temperature Tp.

Now, it is assumed that the detected temperature Tp exceeds the upper temperature Tu. In this case, since the upper temperature Tu is set to a temperature at which the coolant W does not freeze even when the circulation pump 3 is stopped, the coolant W does not freeze even when the circulation pump 3 is in a normal continuous stop state. Meanwhile, the temperature has dropped,
When the detected temperature Tp becomes lower than or equal to the upper temperature Tu, there are two types of antifreeze modes depending on the region of the detected temperature Tp, that is, a time control mode in a region where the detected temperature Tp is relatively high and a time control mode in a region where the detected temperature Tp is relatively low. The operation of the circulation pump 3 is controlled by the temperature control mode.

First, if the detected temperature Tp is lower than the upper temperature Tu but higher than the lower temperature Td, the coolant W
Because of the possibility of freezing, the circulating pump 3 is operated intermittently under the conditions of the stop time tx and the operation time ty. At this time, since the operation time ty is set to a time at which the coolant W goes through at least one circulation path, the temperature distribution of the coolant W is averaged. The temperature is raised.

Further, when the air temperature further decreases, the detected temperature Tp
Becomes lower than or equal to the lower temperature Td, the cooling liquid W is operated even when the circulation pump 3 is intermittently operated in the above-described time control mode.
Is frozen, the circulation pump 3 is continuously operated in the temperature control mode. At this time, the circulating coolant W
Is gradually heated by the heat generated by the circulation pump 3,
When the temperature of the coolant W rises to the middle temperature Tm, the operation of the circulation pump 3 is stopped, and control is performed in the above-described time control mode.

Therefore, in the freeze prevention mode, the circulation pump 3
, The operation of the circulating pump 3 is reliably prevented from being frozen, and the waste of operation is reduced, so that economy and energy saving are improved. In addition, since the temperature distribution of the coolant W is averaged, it is not necessary to select a specific location for temperature detection. Therefore, the temperature sensor 5 can also be used as a temperature sensor used for controlling the temperature of the coolant W, Sensors and their mounting are not required.

[0016]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, an outline of a cooling device that can carry out the cooling liquid freezing prevention method according to the present invention will be described with reference to FIG.

In FIG. 3, reference numeral 4 denotes an object to be cooled, which can be applied to, for example, a heat-generating machine tool (such as a laser beam machine) installed in a factory M.

On the other hand, a cooling device 1 is installed outdoors. The cooling device 1 includes a cooling liquid tank 10 containing a cooling liquid (generally, cooling water) W. A water supply port 11 s of the cooling liquid tank 10 is connected to a suction port of a circulation pump 3 built in the cooling device 1. Return water port 11 of coolant tank 10
r is connected to an outlet of a cooler 2 using, for example, a refrigerator built in the cooling device 1. The discharge port of the circulation pump 3 and the inflow port of the cooler 2 are connected to a cooling pipe 12 c passing through the object 4 to be cooled.
Are connected by a pipe 12 including

On the other hand, the pipe 1 close to the discharge port of the circulation pump 3
2 is provided with a temperature sensor 5 for detecting the temperature of the coolant W. The temperature sensor 5 is connected to a control unit 13 and controls the circulation pump 3 and the cooler 2 by the control unit 13. In this case, the temperature sensor 5 is used for both the temperature control of the coolant W in the normal operation mode and the temperature detection in the freeze prevention mode of the present invention.

Therefore, while operating the cooler 2,
When the circulation pump 3 is operated, the coolant W in the coolant tank 10 is supplied to the pipe 12 by the circulation pump 3 and the coolant W
Reaches the cooler 2 through the cooling pipe 12c. At this time, the object to be cooled 4 is cooled (heat exchanged) by the cooling liquid W. Also,
Since the coolant W flowing into the cooler 2 is warmed, the coolant W is returned to the coolant tank 10 after being cooled by the cooler 2. Therefore, from the coolant tank 10, the circulation pump 3, the pipe 12 including the cooling pipe 12c, the cooler 2,
The route returning to the coolant tank 10 is a circulation route for the coolant W. In this case, the temperature of the coolant W is detected by the temperature sensor 5, and the control unit 13 controls the cooler 2 and the circulation pump 3.
Is controlled, whereby the temperature of the coolant W is feedback-controlled.

Next, a method for preventing freezing of a coolant according to the present invention will be described with reference to FIGS.

First, the control unit 13 previously stores the upper temperature T
u, middle temperature Tm and lower temperature Td (where Tu> T
m> Td) is set. As each temperature to be set, for example, the upper temperature Tu is 10 ° C., the middle temperature Tm is 5 ° C.,
The lower temperature Td is set to 3 ° C. The upper temperature Tu
Sets the temperature at which the cooling liquid W does not freeze even when the circulation pump 3 is stopped, and can be generally set to 5 to 20 ° C. according to the configuration of the cooling device 1 and its installation status. The lower temperature Tu is set at a temperature at which the coolant W does not freeze when the circulation pump 3 is intermittently operated by the stop time tx and the operation time ty. In general, the configuration of the cooling device 1, its installation status, and the like are set. Can be set at 1 to 10 ° C. depending on the temperature. Furthermore, the middle temperature Tm can be set to an intermediate temperature between the upper temperature Tu and the lower temperature Td, generally 5 to 15 ° C. according to the configuration of the cooling device 1 and its installation status.

On the other hand, the control unit 13 previously stores a stop time tx and an operation time ty when the circulation pump 3 is intermittently operated.
Set. As each time, for example, the stop time tx is set to 30 minutes, and the operation time ty is set to 2 minutes. In addition, the operation time ty can be set to be equal to or longer than the time for the coolant W to make a round of the circulation path of the coolant W, and the stop time tx is set to 5 to 60 minutes according to the configuration of the cooling device 1 and its installation status. it can.

In the freeze prevention mode, the coolant W
Is detected by the temperature sensor 5, and the detection result (detected temperature Tp) is given to the control unit 13.

When the detected temperature Tp is higher than the upper temperature Tu, the upper temperature Tu is set to a temperature at which the coolant W does not freeze even when the circulation pump 3 is in a normal continuous stop state. Does not freeze even if is stopped (steps S1 and S2).

On the other hand, if the detected temperature Tp becomes lower than or equal to the upper temperature Tu at time t ₁ in FIG. 1 at time t ₁ in FIG. The pump 3 is intermittently operated according to the conditions of the stop time tx and the operation time ty (steps S2 to S6). That is, the stop time t
x, and at time t ₂ (t ₄ , t ₁₀ ) in FIG. 1, the circulating pump 3 is operated (steps S3 and S3).
4) When the operation time ty has elapsed and the time t ₃ (t ₅ , t ₁₁ ) has been reached, the circulation pump 3 is stopped (steps S5 and S5).
6). In this case, the coolant W is not sufficiently warmed by the circulation pump 3, but the operation time ty is set to a time at which the coolant W makes at least one cycle of the circulation path, so that the temperature distribution of the coolant W is averaged. In particular, the temperature of the coolant W at a low temperature is increased by the temperature at a high temperature. Therefore, even when the detected temperature Tp becomes lower than the upper temperature Tu, if the temperature is relatively high, sufficient freezing prevention is achieved.

On the other hand, if the detected temperature Tp becomes lower than or equal to the lower temperature Td at time t ₆ (t ₈ ) in FIG. 1, the circulation pump 3 is operated intermittently by the above-described time control mode. Since the coolant W may freeze even in the case of operation, the circulation pump 3 is continuously operated in the temperature control mode (steps S3 and S7). As a result, the circulating coolant W is gradually warmed by the heat generated by the circulation pump 3, so that the temperature of the coolant W increases at time t.
_{At 7} (t ₉ ), if the temperature has risen to the medium temperature Tm, the operation of the circulation pump 3 is stopped, and control is performed in the time control mode described above (steps S8, S1).

Therefore, in this embodiment, since accurate operation control of the circulation pump 3 can be performed, freezing of the circulation pump 3 can be reliably prevented. In addition, since waste of operation can be reduced, economy and energy saving can be improved. Furthermore, the temperature sensor 5
Can also be used as a temperature sensor used for controlling the temperature of the coolant W, so that a dedicated temperature sensor and its attachment are not required, and the cost can be reduced.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The configuration and method of the details, particularly the setting conditions of the temperature and the time, can be arbitrarily changed without departing from the gist of the present invention.

[0031]

As described above, the method for preventing the freezing of the cooling liquid of the cooling device according to the present invention uses the upper temperature Tu and the intermediate temperature T in advance.
m and the lower temperature Td, and the temperature of the coolant is detected by a temperature sensor.
u or lower and exceeds the lower temperature Td,
Since the circulation pump is operated intermittently by the stop time tx and the operation time ty, and when the detected temperature Tp becomes lower than the lower temperature Td, the circulation pump is continuously operated until the detected temperature Tp becomes the middle temperature Tm. This has the remarkable effect that not only freezing can be reliably prevented, but also economic efficiency and energy saving can be improved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a temperature characteristic of a cooling liquid with respect to time according to a cooling liquid freezing prevention method according to the present invention;

FIG. 2 is a flowchart showing a control processing procedure according to the cooling liquid freeze prevention method;

FIG. 3 is a block diagram of a cooling device capable of implementing the same cooling liquid freezing prevention method;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cooling device 2 Cooler 3 Circulation pump 4 Object to be cooled 5 Temperature sensor W Coolant Tu Upper temperature Tm Middle temperature Td Lower temperature Tp Detection temperature tx Stop time ty Operating time

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-120153 (JP, A) JP-A-62-13962 (JP, A) JP-A-4-28985 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) F25D 13/00 F25B 47/02

Claims (6)

(57) [Claims] In a cooling liquid freezing prevention method for a cooling device for cooling a cooling object by circulating the cooling liquid cooled by a cooler to the object to be cooled by a circulation pump, an upper temperature Tu and an intermediate temperature are determined in advance. Tm and lower temperature Td (where T
u>Tm> Td), the temperature of the coolant is detected by a temperature sensor, and the detected temperature Tp is set to the upper temperature Tu.
When the temperature is lower than the lower temperature Td, the circulating pump is operated intermittently by the stop time tx and the operation time ty. When the detected temperature Tp becomes lower than the lower temperature Td, the detected temperature Tp becomes the middle temperature. A method for preventing a cooling liquid from freezing in a cooling device, comprising continuously operating a circulation pump until the temperature reaches Tm. 2. The method according to claim 1, wherein the temperature sensor is also used as a temperature sensor used for controlling the temperature of the cooling liquid. 3. The stop time tx during intermittent operation is 5 to 5.
2. The method according to claim 1, wherein the cooling time is set to 60 minutes. 4. The method according to claim 1, wherein the operation time ty at the time of the intermittent operation is set to be equal to or longer than a time during which the coolant makes a round of the coolant circulation path. 5. The method according to claim 1, wherein the upper temperature Tu is set to a temperature at which the coolant does not freeze even when the circulation pump is stopped. 6. The lower temperature Td is used to stop the circulation pump during a stop time t.
2. The cooling liquid freezing prevention method for a cooling device according to claim 1, wherein the temperature is set to a temperature at which the cooling liquid does not freeze if intermittent operation is performed according to x and the operation time ty.