JP7575693B2 - Refrigeration unit - Google Patents

Description

This disclosure relates to a refrigeration unit.

Patent Document 1 discloses a liquid cooling device that cools liquids such as grinding fluid and lubricating oil for machine tools. The liquid is stored in a tank and circulates between the tank and the machine tool. The liquid cooling device is disposed inside the tank and cools the liquid that flows into the tank from the machine tool.

JP 2015-68522 A

To cool the liquid in such a tank, using multiple refrigerators provides a greater cooling effect than using a single refrigerator. However, if there is unevenness in the temperature of the liquid in the tank, the refrigerators in positions where the liquid temperature is relatively high will be under a higher operating load than the refrigerators in positions where the liquid temperature is relatively low, and may break down sooner.
An object of the present disclosure is to relatively easily control the capacities of multiple refrigerators that are used simultaneously.

A first aspect of the present disclosure is a method for manufacturing a semiconductor device comprising:
The refrigerator unit includes a first refrigerator (1) and a second refrigerator (2) that cool a liquid circulating between a machine tool (M) and a tank (T), a first control unit (C1) that controls the cooling capacity of the first refrigerator (1), and a second control unit (C2) that controls the cooling capacity of the second refrigerator (2), wherein the first control unit (C1) adjusts a capacity ratio of the first refrigerator (1) to a first ratio so that the temperature of the liquid becomes a target value, and transmits a control signal related to the capacity ratio to the second control unit (C2), and the second control unit (C2) adjusts the capacity ratio of the second refrigerator (2) to a second ratio based on the control signal.

In the first aspect, the capacity ratio of the second control unit (C2) can be controlled based on a control signal transmitted by the first control unit (C1). This allows the second ratio to be controlled while taking into consideration the value of the first ratio, so that, for example, it is possible to prevent the first ratio from becoming significantly larger than the second ratio. As a result,
This prevents the operating load from being concentrated solely on the first refrigerator (1), thereby preventing breakdowns in the first refrigerator (1). In addition, since the liquid in the tank (T) is cooled by multiple refrigerators (1, 2), the liquid temperature can be adjusted to a target temperature more quickly than if a single refrigerator were used for cooling.

A second aspect of the present disclosure is a method for producing a composition comprising the steps of:
The control signal includes a signal indicating a first ratio, and the second control section (C2) adjusts the second ratio of the second refrigerator (2) based on the control signal so that the second ratio becomes equal to the first ratio.

In the second embodiment, the second refrigerator (2) is adjusted to the same capacity ratio as the first refrigerator (1). This prevents one of the refrigerators from being overloaded, and prevents overload operation. In addition, the operating load of the multiple refrigerators (1, 2) can be controlled relatively easily by simply transmitting a control signal.

A third aspect of the present disclosure is the first or second aspect,
The control signal has a first signal and a second signal that are transmitted alternately, and the first ratio is determined based on a ratio between a first time from when the first signal is output at the start of a predetermined period to when the second signal is output, and a second time from when the second signal is output to when the predetermined period ends.

In the third aspect, a control signal representing the first ratio can be transmitted by adjusting the ratio between the first time and the second time. In this way, a complex control signal is not required, and the capacity ratio (second ratio) of the second refrigerator can be controlled relatively simply.

A fourth aspect of the present disclosure is the third aspect,
When an index indicating a ratio of the first time to the predetermined period is defined as a first index,
The first index and the first ratio have a positive correlation,
When the first ratio is zero percent, the first index indicates a value higher than zero.

In the fourth aspect, if the first index is set to zero% when the first ratio is zero%, it is impossible to determine whether the first index is zero% because the first ratio is zero% or because of a malfunction such as an inability to output the first signal. Therefore, by setting the first index to a value higher than zero when the first ratio is zero%, it is possible to distinguish between the two.

A fifth aspect of the present disclosure relates to the third aspect,
When an index indicating a ratio of the first time to the predetermined period is defined as a first index,
The first index and the first ratio have a positive correlation,
When the first ratio is 100%, the first index indicates a value lower than the maximum value of the first index.

In the fifth aspect, if the first index is set to 100% (maximum value) when the first ratio is 100%, it is impossible to determine whether the first index is 100% because the first ratio is 100% or because of a malfunction such as an inability to output the second signal. Therefore, by setting the first index to a value lower than the maximum value of the first index when the first ratio is 100%, it is possible to distinguish between the two.

A sixth aspect of the present disclosure is any one of the third to fifth aspects,
When an index indicating a ratio of the first time to the predetermined period is defined as a first index,
The first index and the first ratio have a positive correlation,
The amount of change in the first index when the first ratio changes between 0% and 1%, where X is a number from 1 to 98, is greater than the amount of change in the first index when the first ratio changes between X% and X+1%.

In the sixth aspect, when the first ratio becomes zero%, the operation of the first refrigerator (1) and the second refrigerator (2) stops. When the refrigerators (1, 2) stop operating, a certain time is required for them to start operating again, so it is undesirable for the first ratio to be erroneously detected as zero%. Therefore, when the first ratio changes between zero% and 1%, the amount of change in the first index is made larger than the other values, thereby making it possible to suppress erroneous detection.

A seventh aspect of the present disclosure is any one of the first to sixth aspects,
The first refrigerator (1) and the second refrigerator (2) are disposed in the same tank (T).

In the seventh aspect, even if temperature unevenness occurs in the liquid in the same tank (T), it is possible to prevent a load from being imposed on the refrigerator (1, 2) located at a relatively high liquid temperature compared to the refrigerator (1, 2) located at a relatively low liquid temperature.

An eighth aspect of the present disclosure is the seventh aspect,
The tank (T) has an outlet (P2) through which liquid flows out toward the machine tool (M) and an inlet (P1) through which liquid flows from the machine tool (M) into the tank (T),
The first refrigerator (1) is disposed at a position closer to the inlet (P1) than the second refrigerator (2).

In the eighth aspect, the liquid temperature in the tank (T) is higher the closer it is to the inlet (P1) through which the liquid heated by the machine tool (M) flows. Therefore, if the first refrigerator (1) is arranged relatively close to the inlet (P1) and the second refrigerator (2) is arranged farther from the inlet (P1) than the first refrigerator (1), the operating load will be concentrated on the first refrigerator (1). However, by having the first control unit (C1) control the capacity ratio of the second control unit (C2), such overload operation of the first refrigerator (1) can be avoided.

FIG. 1 is a perspective view of a refrigerator unit according to an embodiment installed in a tank. FIG. 2 is a schematic diagram showing the configuration of the refrigerator. FIG. 3 is a block diagram showing the relationship between the control unit of the refrigerator and various devices. FIG. 4 is a schematic diagram showing a tank in which the first refrigerator and the second refrigerator are disposed, as viewed from above. FIG. 5 is a diagram illustrating a control signal transmitted from the first control unit to the second control unit. FIG. 6 is a diagram illustrating an example of graph data stored in the first control unit. FIG. 7 is a flowchart showing the control of the refrigerator unit. FIG. 8 is a schematic diagram showing connections of refrigerators in a refrigerator unit according to another embodiment.

The following describes embodiments of the present invention with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses. Furthermore, the configurations of the embodiments, variations, other examples, etc. described below can be combined or partially substituted within the scope of the present invention.

(1) Overall Configuration of Refrigeration Unit As shown in FIG. 1, the refrigerator unit (U) of this embodiment is applied to a system (S) including a machine tool (M) and a tank (T) in which machining fluid circulates between the machine tool (M) and the tank (T). The refrigerator unit (U) is disposed in the tank (T) and cools the machining fluid in the tank (T). The machine tool (M) of this example is a machine that performs cutting processing, such as a grinding machine or a machining center. The machining fluid is the liquid disclosed herein. The machining oil is, for example, cutting oil. The cutting oil has the effect of reducing tool wear through its lubricating effect and suppressing a decrease in machining accuracy through its cooling effect.

The tank (T) stores machining fluid. During operation of the machine tool (M), the amount of machining fluid stored in the tank (T) is maintained approximately constant. The tank (T) is provided with an inlet (P1) and an outlet (P2). A pipe (5) leading to the machine tool (M) is connected to the inlet (P1) and the outlet (P2). A pump (not shown) is connected to the pipe (5). The pump adjusts the flow direction and flow rate of the machining fluid flowing through the pipe (5). When the pump is operated, the liquid flowing out of the machine tool (M) flows into the tank (T) through the inlet (P1). The machining fluid in the tank (T) flows out toward the machine tool (M) through the outlet (P2).

The machining fluid that flows out of the tank (T) is heated by the machine tool (M). The heated machining fluid flows into the tank (T) and is cooled by the refrigerator unit (U). This prevents the temperature of the machining fluid in the tank (T) from rising.

The refrigerator unit (U) in this example has a first refrigerator (1) and a second refrigerator (2). The first refrigerator (1) and the second refrigerator (2) are arranged in a tank (T). The first refrigerator (1) is arranged relatively close to the inlet (P1). The second refrigerator (2) is arranged farther from the inlet (P1) than the first refrigerator (1). The second refrigerator (2) is arranged relatively close to the outlet (P2).

The configurations of the first refrigerator (1) and the second refrigerator (2) are described below. Note that since the first refrigerator (1) and the second refrigerator (2) have the same configuration, they may be collectively referred to as refrigerators (1, 2).

(2) Configuration of the Refrigerator As shown in Figs. 1 and 2, the refrigerator (1, 2) of this example includes a casing (11), a compressor (12), a condenser (13), an expansion valve (14), an evaporator (15), a blower fan (16), an agitator (17), a liquid temperature sensor (22), and an operation panel (21). The compressor (12), the condenser (13), the expansion valve (14), and the evaporator (15) are connected in this order to a refrigerant circuit (10). The refrigerant circuit (10) is filled with refrigerant. The refrigerant circuit (10) performs a vapor compression refrigeration cycle. The compressor (12), the condenser (13), and the expansion valve (14) are disposed within the casing (11).

(2-1) Casing The casing (11) is formed in a box shape extending in the vertical direction. The bottom of the casing (11) is open. The casing (11) is placed above the liquid level in the tank (T). Legs (18) are connected to the four corners of the bottom end of the casing (11). The bottom ends of the legs (18) are installed on the bottom surface of the casing (11). In this manner, the casing (11) is supported by the four legs (18).

(2-2) Compressor The compressor (12) draws in and compresses low-pressure gas refrigerant. The compressor (12) discharges the compressed refrigerant. The compressor (12) is of a variable displacement type in which power is supplied to the electric motor from an inverter circuit. In other words, the compressor (12) is configured so that the operating frequency (rotation speed) of the electric motor is adjustable.

(2-3) Condenser The condenser (13) exchanges heat between the refrigerant and the air transported by the blower fan (16). Specifically, in the condenser (13), the refrigerant dissipates heat into the air and is condensed. The blower fan (16) is disposed near the condenser (13) and transports the air passing through the condenser (13).

(2-4) Expansion Valve The expansion valve (14) reduces the pressure of the refrigerant. The expansion valve (14) is an electrically operated expansion valve whose opening is adjustable. The expansion valve (14) may be a temperature-sensitive expansion valve, a capillary tube, or the like.

(2-5) Evaporator The evaporator (15) is disposed below the lower end of the casing (11). The evaporator (15) is disposed so as to be immersed in the machining fluid in the tank (T). The evaporator (15) exchanges heat between the machining fluid in the tank (T) and the refrigerant. Specifically, in the evaporator (15), the refrigerant absorbs heat from the machining fluid and evaporates. The evaporator (15) is formed in a coil shape extending in the vertical direction.

(2-6) Agitator The agitator (17) is disposed so as to be immersed in the machining fluid in the tank (T). The agitator (17) agitates the machining fluid in the tank (T). By disposing the agitator (17) in the vicinity of the evaporator (15), heat exchange between the refrigerant and the machining fluid is promoted.

(2-7) Liquid temperature sensor The liquid temperature sensor (22) is disposed so as to be immersed in the machining fluid in the tank (T). The liquid temperature sensor (22) of the first refrigerator (1) detects the temperature of the machining fluid in the vicinity of the first refrigerator (1). The liquid temperature sensor (22) of the second refrigerator (2) detects the temperature of the machining fluid in the vicinity of the second refrigerator (2). The temperature of the machining fluid may represent an average value of the detection values of the liquid temperature sensors (22) of the first refrigerator (1) and the second refrigerator (2), or, in the case where a liquid temperature sensor is provided at a predetermined position in the tank (T) separately from the liquid temperature sensor (22), the temperature of the machining fluid may represent the value of the liquid temperature sensor.

(2-8) Operation Panel The chiller unit (U) has an operation panel (21). The operation panel (21) receives predetermined operation instructions through operation by a user. The operation panel (21) has a display (not shown) that displays the liquid temperature. The operation panel (21) is disposed on a side surface of the casing (11). In this example, the operation panel (21) is provided in the first chiller (1) and the second chiller (2).

(3) Control Unit As shown in Fig. 3, the refrigerator unit (U) has a first control unit (C1) and a second control unit (C2). Each of the first control unit (C1) and the second control unit (C2) is configured with a microcomputer. The first control unit (C1) and the second control unit (C2) are connected to each other via a wire so as to be able to communicate with each other. The first control unit (C1) and the second control unit (C2) may be connected to each other wirelessly.

(3-1) First Control Unit The first control unit (C1) is provided in the first refrigerator (1). The first control unit (C1) is connected to various devices of the first refrigerator (1) and the liquid temperature sensor (22) via communication lines. The first control unit (C1) controls various devices of the first refrigerator (1), such as the compressor (12), the blower fan (16), and the agitator (17). The first control unit (C1) controls the cooling capacity of the first refrigerator (1). Specifically, the first control unit (C1) adjusts the capacity ratio of the first refrigerator (1) so that the temperature of the working fluid becomes a target value. The capacity ratio indicates the proportion of the capacity in the rated capacity of the refrigerator. The capacity ratio is adjusted by controlling the operation of various devices, such as the compressor (12) and the blower fan (16).

The first control unit (C1) receives information such as an operation ON/OFF command by a user, a target temperature of the working fluid, and a detection value of the fluid temperature sensor (22). In this example, the target temperature of the working fluid is input by a user through an operation panel (21).

The first control unit (C1) stores the current capacity ratio of the first refrigerator (1). The first control unit (C1) also stores the past operation history of the first refrigerator (1). The operation history includes, for example, the operation time of the first refrigerator (1), the history of the detection value of the liquid temperature sensor (22), the history of the rotation speed of the compressor (12), etc.

The first control unit (C1) transmits a control signal related to the capacity ratio to the second control unit (C2). Details of this control signal will be described later.

(3-2) Second Control Unit The second control unit (C2) is provided in the second refrigerator (2). The second control unit (C2) is connected to various devices of the second refrigerator (2) and the liquid temperature sensor (22) via communication lines. The second control unit (C2) controls various devices of the second refrigerator (2), such as the compressor (12), the blower fan (16), and the agitator (17). The second control unit (C2) controls the cooling capacity of the second refrigerator (2). Specifically, the second control unit (C2) adjusts the capacity ratio of the second refrigerator (2) based on a control signal transmitted from the first control unit (C1).

The second control unit (C2) receives the control signal sent from the first control unit (C1) and the detection value of the liquid temperature sensor (22).

The second control unit (C2) stores the current capacity ratio of the second refrigerator (2). The second control unit (C2) also stores the past operation history of the second refrigerator (2). The operation history includes, for example, the operation time of the second refrigerator (2), the history of the detection value of the liquid temperature sensor (22), the history of the rotation speed of the compressor (12), etc.

(4) Operation The operation of each of the chillers (1, 2) of the chiller unit (U) will be described. Since the first chiller (1) and the second chiller (2) have the same configuration, the operation of only the first chiller (1) will be described below.

The first control unit (C1) operates the compressor (12), the blower fan (16), and the agitator (17). The first control unit (C1) controls the compressor (12) and the blower fan (16) based on the set temperature input to the operation panel (21). The first control unit (C1) appropriately adjusts the rotation speed of the agitator (17).

The refrigerant compressed by the compressor (12) flows through the condenser (13). In the condenser (13), the refrigerant releases heat to the air and condenses. The refrigerant that released heat in the condenser (13) is reduced in pressure by the expansion valve (14) and then flows through the evaporator (15). In the evaporator (15), the refrigerant absorbs heat from the working fluid and evaporates. The working fluid cooled by the evaporator (15) is stirred by the stirrer (17), preventing the temperature of the liquid in the tank (T) from rising. The refrigerant that evaporated in the evaporator (15) is sucked into the compressor (12) and compressed again.

(5) Issues when multiple refrigerators are placed in a tank When cooling machining fluid in a tank, using multiple refrigerators rather than a single refrigerator provides a greater cooling effect, can prevent a sudden rise in the machining fluid's temperature, and can maintain a stable liquid temperature.

As shown in FIG. 4, the temperature of the fluid near the inlet (P1) (area A in FIG. 4) where the machining fluid heated by the machine tool (M) flows in is higher than the temperature of the fluid near the outlet (P2) (area B in FIG. 4) where the machining fluid cooled by the refrigerators (1, 2) flows out. Since the temperature of the fluid in the tank (T) is uneven, the first refrigerator (1) located near the inlet (P1) has a higher operating load than the second refrigerator (2) located near the outlet (P2). Therefore, if only the first refrigerator (1) continues to operate under an overload, the first refrigerator (1) may break down earlier than the second refrigerator (2). In order to eliminate such an imbalance in the operating load, a method of performing feedback control on the multiple refrigerators (1, 2) individually may be considered. However, this method not only complicates the control, but also requires a communication board, which is costly.

To address this issue, in the refrigerator unit (U) of the present disclosure, the capacity ratio of the second refrigerator (2) is adjusted based on the capacity ratio of the first refrigerator (1). Specifically, the first control unit (C1) adjusts the capacity ratio of the first refrigerator (1) to a first ratio so that the temperature of the working fluid becomes a target value, and transmits a control signal related to the first ratio to the second control unit (C2). Based on this control signal, the second control unit (C2) adjusts the capacity ratio of the second refrigerator (2) to a second ratio. Below, a method of controlling the capacity ratio of the refrigerators (1, 2) of the present disclosure will be described.

(6) Control Method The control signal of this example includes a signal indicating a first ratio, which is a capacity ratio of the first refrigerator (1). The second control unit (C2) adjusts the second ratio of the second refrigerator (2) based on this control signal so that it becomes equal to the first ratio. In this way, the first refrigerator (1) and the second refrigerator (2) operate at the same capacity ratio. The control method of this example will be described in more detail below.

The second refrigerator (2) has a circuit that controls the second ratio. This circuit is, for example, a relay circuit. In this relay circuit, a contact is switched on and off by a control signal received from the first control unit (C1). The control signal has an on signal that turns the contact on and an off signal that turns the contact off. The on signal is an example of a second signal of the present disclosure. The off signal is an example of a first signal of the present disclosure. The on signal and the off signal are transmitted alternately. In this way, the on signal and the off signal are transmitted alternately, so that the relay circuit repeats an on state (contact connected) and an off state (contact separated).

As shown in FIG. 5, the first ratio in this example is determined based on the time ratio between the duration of the off state and the duration of the on state during the specified period. In this example, the specified period is 10 seconds. The duration of the off state is the first time in this disclosure. The duration of the off state is the time from when the off signal is output at the start of the specified period to when the on signal is output. The duration of the on state is the second time in this disclosure. The duration of the on state is the time from when the on signal is output at the end of the first time to when the specified period ends.

In this example, the first ratio is calculated based on the proportion of the duration of the off state during a predetermined period of 10 seconds. In this way, information on the value of the first ratio is transmitted every 10 seconds, making it possible to know the value of the first ratio in real time.

As shown in FIG. 6, the first control unit (C1) in this example has graph data showing the relationship between the first ratio and the first index. The first index is based on the ratio of the first time to a predetermined period of 10 seconds. The first index in this example indicates the ratio of the first time to 10 seconds (sec/10 sec). The first index may be expressed as a percentage.

The first ratio and the first index have a positive correlation. In other words, the higher the value of the first ratio, the higher the value of the first index. Specifically, the relationship between the first ratio and the first index is expressed by a linear function (I) with a predetermined slope α when the value of the first ratio is 1% to 99%. The linear function (I) is expressed as the first index (seconds/10 seconds) = (100 + capacity command value x 8)/100. The capacity command value indicates the value of the first ratio (%). When the value of the first ratio is 0% to 1%, it is expressed by a linear function with a predetermined slope β. The slope β is greater than the slope α. Therefore, the amount of change in the first index when the first ratio changes between 0% and 1% is greater than the amount of change in the first index when the first ratio changes between X% and X+1%, where X is a number between 1 and 98. When the value of the first ratio is 99% to 100%, it is expressed by a linear function with a predetermined slope γ. The slope γ is greater than the slope α.

In this way, the first control unit (C1) adjusts the timing of outputting the on signal and the off signal so as to obtain the first index according to the current value of the first ratio. For example, when the first ratio is 80%, an on signal is transmitted 7.4 seconds after an off signal is transmitted at the start of the specified period. An off signal is transmitted again 2.6 seconds after the on signal is transmitted. When the first ratio is 40%, an on signal is transmitted 4.2 seconds after an off signal is transmitted. An off signal is transmitted again 5.8 seconds after the on signal is transmitted. In this way, on signals and off signals are transmitted alternately.

When the first ratio is zero%, the first indicator indicates 0.5 seconds/10 seconds. Thus, when the first ratio is zero%, the first indicator indicates a value higher than zero seconds/10 seconds. Also, when the first ratio is 100%, the first indicator indicates 9.5 seconds/10 seconds. Thus, when the first ratio is 100%, the first indicator indicates a value lower than 10 seconds/10 seconds.

The second control unit (C2) adjusts the second ratio of the second refrigerator (2) based on the first index. Specifically, the second control unit (C2) also has data similar to the graph data held by the first control unit (C1), and determines the second ratio based on the first index received from the first control unit (C1). Since the first index indicates the first ratio, the second ratio is adjusted to be equal to the first ratio. In this way, the refrigerator unit (U) operates the first refrigerator (1) and the second refrigerator (2) at the same capacity ratio.

(7) Control Flow Next, the flow of control performed by the refrigerator unit (U) of this embodiment will be described with reference to FIG.

In step S1, the first control unit (C1) turns on the power of the first refrigerator (1) in response to a user operation. The second control unit (C2) turns on the power of the second refrigerator (2) in response to a user operation.

In step S2, the first control unit (C1) sets a target temperature of the machining fluid in the tank (T). The target temperature is set by a user through the operation panel (21).

In step S3, the first control unit (C1) starts the operation of the first refrigerator (1). The second control unit (C2) starts the operation of the second refrigerator (2).

In step S4, the first control unit (C1) determines whether the liquid temperature in the tank (T) is the target temperature. If the liquid temperature in the tank (T) is the target temperature (YES in step S4), step S10 is executed. If the liquid temperature in the tank (T) is not the target temperature (NO in step S4), step S5 is executed again. This step S9 may be executed by the second control unit (C2).

In step S5, the first control unit (C1) adjusts the first ratio of the first refrigerator (1) based on the current temperature of the machining fluid and the target temperature set in step S2. The current temperature of the machining fluid is a detection value of the fluid temperature sensor (22) of the first refrigerator (1). The current temperature of the machining fluid may be the average temperature of the machining fluid in the tank (T).

In step S6, the first control unit (C1) controls the cooling capacity of the first refrigerator (1) based on the first ratio adjusted in step S5. Specifically, the first control unit (C1) controls various devices such as the compressor (12) and the blower fan (16).

In step S7, the first control unit (C1) transmits a control signal based on the first ratio determined in step S5. Specifically, an on signal and an off signal are transmitted to the second control unit (C2) in accordance with the first ratio determined in step S5.

In step S8, the second control unit (C2) adjusts the second ratio based on the control signal output in step S7.

In step S9, the second control unit (C2) controls the cooling capacity of the second refrigerator (2) based on the second ratio adjusted in step S8. Specifically, the second control unit (C2) controls various devices such as the compressor (12) and the blower fan (16).

In step S10, the first control unit (C1) determines whether a signal to stop the operation of the first refrigerator (1) has been input by a user operation. If a signal to stop the operation has been input (YES in step S10), the operation of the first refrigerator (1) is stopped. The second refrigerator (2) receives the signal to stop the operation of the first refrigerator (1) and stops the operation of the second refrigerator (2). As a result, the first refrigerator (1) and the second refrigerator (2) stop operating simultaneously. Also, a signal to stop the operation of the second refrigerator (2) may be input directly by a user operation. Even in this case, the second control unit (C2) stops the operation of the second refrigerator (2). If a signal to stop the operation has not been input (NO in step S10), step S4 is executed again.

(8) Features (8-1)
In the refrigerator unit (U) of this embodiment, the first control section (C1) adjusts the capacity ratio of the first refrigerator (1) to a first ratio so that the temperature of the working fluid becomes a target value, and transmits a control signal related to the capacity ratio to the second control section (C2). The second control section (C2) adjusts the capacity ratio of the second refrigerator (2) to a second ratio based on the control signal.

By controlling the second ratio while taking into account the value of the first ratio, the operating load of the first refrigerator (1) can be shared by the second refrigerator (2), and the capacity ratio can be distributed so that the operating load is not concentrated on one of the refrigerators (1, 2). As a result, the operating load is prevented from being concentrated only on the first refrigerator (1), and breakdowns of the first refrigerator (1) can be suppressed.

In addition, when the first refrigerator (1) and the second refrigerator (2) are controlled separately, the first refrigerator (1) and the second refrigerator (2) may be operated with both the first ratio and the second ratio at relatively high values. In such a case, more power than necessary is consumed, which is undesirable from the viewpoint of energy and cost savings. However, in this example, the first control unit (C1) adjusts the capacity ratio of the second control unit (C2), so that both the first ratio and the second ratio can be prevented from becoming high, and energy and cost savings can be achieved.

(8-2)
In the chiller unit (U) of this embodiment, the control signal includes a signal indicating the first ratio, and the second control section (C2) adjusts the second ratio of the second chiller (2) based on the control signal so that it becomes equal to the first ratio.

As a result, the second refrigerator (2) is adjusted to the same capacity ratio as the first refrigerator (1). As a result of suppressing the load on the first refrigerator (1), overload operation can be suppressed. In addition, the operating load of the two refrigerators (1, 2) can be controlled relatively easily by simply transmitting a control signal.

(8-3)
In the refrigerator unit (U) of this embodiment, the control signal includes an off signal (first signal) and an on signal (second signal) that are alternately transmitted. The first ratio is determined based on the ratio between a first time from when the first signal is output at the start of a predetermined period (10 seconds in this example) to when the second signal is output, and a second time from when the second signal is output to when the predetermined period ends.

In this way, the first ratio can be easily displayed by simply adjusting the time ratio between the first time and the second time. Therefore, the capacity ratio of the second refrigerator can be controlled relatively easily without using a complex control signal.

(8-4)
In the refrigeration unit (U) of this embodiment, when an index indicating the ratio of a first time to a predetermined period (10 seconds) is defined as a first index, the first index and the first ratio have a positive correlation, and when the first ratio is zero percent, the first index indicates a value higher than zero.

If the first ratio is zero% and the first index is expressed as zero seconds/10 seconds, the contacts of the relay circuit are always in the on state throughout the specified period (10 seconds) and never in the off state. This state can occur when an off signal is not sent due to some kind of malfunction, or when the relay circuit is broken (the contacts do not switch from on to off). Therefore, there are cases where it is not possible to determine whether the first ratio is zero% or whether there is a malfunction in sending the off signal or a malfunction in the relay circuit. However, when the first ratio is zero%, the first index indicates a value higher than zero seconds/10 seconds, making it possible to distinguish between cases where the first ratio is zero% and cases where it is not (such as cases of relay circuit failure).

(8-5)
In the refrigeration unit (U) of this embodiment, when an index indicating the ratio of the first time to the second time is defined as a first index, the first index and the first ratio have a positive correlation, and when the first ratio is 100%, the first index indicates a value lower than 10 seconds/10 seconds, which is the maximum value of the first index.

If the first ratio is 100% and the first index is expressed as 10 seconds/10 seconds, the contacts of the relay circuit are always in the OFF state for 10 seconds and never in the ON state. This state can occur when an ON signal is not being sent due to some kind of malfunction, or when the relay circuit has a failure (when the contacts do not switch from OFF to ON). Therefore, there are cases where it is not possible to determine whether the first ratio is in the 100% state or whether there is a malfunction in sending the ON signal or a malfunction in the relay circuit. However, when the first ratio is 100%, the first index indicates a value lower than 10 seconds/10 seconds, making it possible to distinguish between cases where the first ratio is 100% and cases where it is not (such as cases of relay circuit failure).

(8-6)
In the refrigerator unit (U) of the present embodiment, when an index indicating a ratio of a first time to a predetermined period is defined as a first index, the first index and the first ratio have a positive correlation, and an amount of change in the first index when the first ratio changes between 0% and 1% is greater than an amount of change in the first index when the first ratio changes between X% and X+1%, where X is a number from 1 to 98.

When the first ratio becomes zero%, the first refrigerator (1) and the second refrigerator (2) stop operating. It takes a certain amount of time to restart the refrigerators (1, 2) that have stopped operating, and during that time, even if the liquid temperature in the tank (T) rises, it will not be able to cool quickly. Therefore, it is necessary to suppress false detection of the first ratio near zero%, but in this example, by making the amount of change in the first index larger only when the first ratio changes between zero% and 1%, it is possible to avoid stopping the operation of the refrigerators (1, 2) due to such false detection.

(8-7)
In the refrigerator unit (U) of this embodiment, the first refrigerator (1) and the second refrigerator (2) are disposed in the same tank (T).

Even if temperature unevenness occurs in the machining fluid within the same tank (T), the first refrigerator (1), which is located at a relatively high liquid temperature, can be prevented from being overloaded compared to the second refrigerator (2), which is located at a relatively low liquid temperature.

(8-8)
In the refrigerator unit (U) of this embodiment, the first refrigerator (1) is disposed at a position closer to the inlet (P1) of the tank (T) than the second refrigerator (2).

In the refrigerator unit (U) of this embodiment, the liquid temperature is higher in the tank (T) closer to the inlet (P1) where the liquid heated by the machine tool (M) flows in. Therefore, if the first refrigerator (1) is placed relatively close to the inlet (P1) and the second refrigerator (2) is placed farther from the inlet (P1) than the first refrigerator (1), the load would normally be concentrated on the first refrigerator (1), which is located at a higher temperature than its surroundings. However, by having the first control unit (C1) control the capacity ratio of the second control unit (C2), such overload operation of the first refrigerator (1) can be avoided.

(9) Other Embodiments The above-described embodiment may be configured as follows.

The first signal may be an on signal and the second signal may be an off signal.

The first indicator may indicate the ratio of the second time to a predetermined period (10 seconds).

The specified period is not limited to 10 seconds. The specified period may be longer than 10 seconds or shorter than 10 seconds.

The first control unit (C1) may be separate from the first refrigerator (1). The second control unit (C2) may be separate from the second refrigerator (2).

The control signal may be any signal capable of suppressing an increase in the capacity ratio of the first refrigerator (1), and the control signal transmitted by the first control unit (C1) does not have to be a signal indicating the first ratio. Therefore, the second ratio does not have to be adjusted to be equal to the first ratio. Furthermore, the control signal does not have to be a signal based on the first ratio. In this case, the second ratio may be, for example, a specific value input by the user.

The information included in the control signal may include, in addition to the first ratio, historical information about the first refrigerator (1). The second ratio may be adjusted taking such historical information into account.

The refrigerator unit (U) may have three or more refrigerators. In this case, the first control unit (C1) and the control units of the other refrigerators are connected in parallel by a communication line, so that a control signal from the first control unit (C1) is transmitted to the control units of the other refrigerators. For example, as shown in FIG. 8, when the refrigerator unit (U) has three refrigerators, the first refrigerator (1), the second refrigerator (2), and the third refrigerator (3), the control signal output from the first control unit (C1) is transmitted to the second control unit (C2) and the control unit of the third refrigerator (3). Even in this case, the second ratio and the capacity ratio of the third refrigerator can be adjusted based on the first ratio, so that the load of the operation can be prevented from being biased only on the first refrigerator (1).

The refrigerator unit (U) does not have to have a relay circuit. The second ratio only needs to be adjusted based on the time ratio between the first time and the second time, and a means other than a relay circuit may be used.

In the above embodiment, predetermined information may be transmitted from the second refrigerator (2) to the first refrigerator (1). In this case, the transmitted information is historical information of the second refrigerator (2). In this way, the first refrigerator (1) may determine the first ratio by also taking into account the historical information of the second refrigerator (2). Since the second ratio is equal to the first ratio, by taking into account the historical information of the second refrigerator (2) in this way, it is possible to determine a first ratio that reduces the operating load on the second refrigerator (2). As a result, it is possible to reduce the operating load on the second refrigerator (2).

The first refrigerator (1) and the second refrigerator (2) do not have to be placed in the same tank (T). The first refrigerator (1) and the second refrigerator (2) may be placed in different tanks (T). Even in this case, for example, even if the liquid temperature in the tank (T) in which the first refrigerator (1) is placed becomes higher than the liquid temperature in the tank (T) in which the second refrigerator (2) is placed, an increase in the capacity ratio of the first refrigerator (1) can be suppressed.

Although the embodiments and modifications have been described above, it will be understood that various modifications of form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate as long as the functionality of the subject matter of this disclosure is not impaired. The descriptions "first," "second," etc. described above are used to distinguish the words to which these descriptions are attached, and do not limit the number or order of the words.

As explained above, the present disclosure is useful for refrigeration units.

M Machine tool T Tank C1 First control unit C2 Second control unit 1 First refrigerator 2 Second refrigerator P1 Inlet P2 Outlet

Claims (7)

a first refrigerator (1) and a second refrigerator (2) for cooling a liquid circulating between a machine tool (M) and a tank (T);
a first control unit (C1) that controls a cooling capacity of the first refrigerator (1), and a second control unit (C2) that controls a cooling capacity of the second refrigerator (2),
the first control unit (C1) adjusts a capacity ratio of the first refrigerator (1) to a first ratio so that the temperature of the liquid becomes a target value, and transmits a control signal related to the capacity ratio to a second control unit (C2);
The second control unit (C2) adjusts a capacity ratio of the second refrigerator (2) to a second ratio based on the control signal,
the control signal includes a first signal and a second signal that are transmitted in a continuous, alternating manner ;
The second ratio is determined based on a ratio between a first time during which the output of the first signal is continued and a second time during which the output of the second signal is continued . the control signal includes a signal indicative of the first ratio;
The refrigerator unit according to claim 1, wherein the second control section (C2) adjusts the second ratio of the second refrigerator (2) based on the control signal so that the second ratio becomes equal to the first ratio. When an index based on a ratio of the first time to a period from the start of the first time to the elapse of a second time that starts when the first time has elapsed is defined as a first index,
The first index and the first ratio have a positive correlation,
3. The refrigerator unit according to claim 1, wherein when the first ratio is zero percent, the first index indicates a value higher than zero. When an index indicating a ratio of the first time to a period from the start of the first time to a second time that starts when the first time has elapsed is defined as a first index,
The first index and the first ratio have a positive correlation,
3. The refrigerator unit according to claim 1, wherein when the first ratio is 100%, the first index indicates a value lower than a maximum value of the first index. When an index indicating a ratio of the first time to a period from the start of the first time to a second time that starts when the first time has elapsed is defined as a first index,
The first index and the first ratio have a positive correlation,
5. The refrigeration unit according to claim 3 or 4, wherein an amount of change in the first indicator when the first ratio changes between 0% and 1% is larger than an amount of change in the first indicator when the first ratio changes between X% and X+1%, where X is a number from 1 to 98. The refrigeration unit according to any one of claims 1 to 5, wherein the first refrigeration unit (1) and the second refrigeration unit (2) are disposed in the same tank (T). The tank (T) has an outlet (P2) through which liquid flows out toward the machine tool (M) and an inlet (P1) through which liquid flows from the machine tool (M) into the tank (T),
The refrigerator unit according to claim 6, wherein the first refrigerator (1) is disposed at a position closer to the inlet (P1) than the second refrigerator (2).

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