WO2019182221A1

WO2019182221A1 - Method of controlling water purifier

Info

Publication number: WO2019182221A1
Application number: PCT/KR2018/012715
Authority: WO
Inventors: Sangjoon Lee; Jongho Park; Seonwoong Hwang
Original assignee: Lg Electronics Inc.
Priority date: 2018-03-23
Filing date: 2018-10-25
Publication date: 2019-09-26
Also published as: KR20190111614A; KR102447108B1

Abstract

A method of controlling a water purifier includes sensing a temperature of coolant using a temperature sensor and transmitting information on the sensed temperature to a controller, driving a compressor and an agitator upon determining that the temperature of the coolant reaches an upper limit temperature, and sensing a rotation speed of the agitator and transmitting information on the sensed rotation speed to the controller. The controller stops the compressor at the moment of sensing deceleration of the agitator.

Description

METHOD OF CONTROLLING WATER PURIFIER

The present invention relates to a method of controlling a water purifier.

A water purifier is a device for filtering out harmful elements such as foreign materials or heavy metals contained in water using physical and/or chemical methods.

The prior art described below discloses a so-called direct type water purifier.

The direct type water purifier means a water purifier for coolant supplied through a water tap to a set temperature through a cooling unit and directly supplying water to a consumer without using a water tank, when the consumer pressing a water supply button.

Since the direct type water purifier does not require the water tank, there is no problem that foreign materials are accumulated on the bottom of the water tank and that bacteria propagate in the water tank.

The direct type water purifier includes a coolant tank in which coolant is stored, an evaporator disposed inside the coolant tank at the upper side thereof, a cold water pipe disposed inside the coolant tank at the lower side thereof, and an agitator configured to circulate water in the coolant tank and to enable heat exchange between drinking water flowing along the cold water pipe and the coolant, as disclosed in the prior art.

Specifically, coolant located at an upper side and cooled by the evaporator flows downwardly toward the cold water pipe by rotation of an agitator and cold water in the space, in which the cold water pipe is received, flows upwardly toward the evaporator.

In addition, when a lump of ice is generated on the surface of the evaporator to accumulate cold air, since heat exchange is performed by latent heat as well as sensible heat, it is possible to cool drinking water passing through the cold water pipe in a short time, which is advantageous for the direct type water purifier.

The direct type water purifier having such a structure and a method of controlling the same are disclosed in the prior art described below.

According to the prior art, the outside temperature of the water purifier and the temperature of the coolant in the vicinity of the cold water pipe are measured and rotation of the agitator is appropriately adjusted based on the measured temperature values, thereby generating and maintaining an appropriate amount of ice on the surface of the evaporator.

However, the method of controlling driving of the agitator disclosed in the prior art has the following problems.

That is, when the temperature sensor installed in the coolant tank does not normally operate due to failure, ice is excessively generated to hinder operation of the agitator. There is no method of preventing from ice from being excessively generated.

In addition, in the prior art, since two temperature sensors should be installed in the coolant tank and a temperature sensor for measuring an outside temperature is further provided, manufacturing costs may increase.

Prior Art Document

Patent Document

Korean Unexamined Patent Publication No. 2015-0019118 (February 25, 2015)

An object of the present invention is to solve the above-described problems.

To achieve the above objects, there is provided a method of controlling a water purifier including sensing a temperature of coolant using a temperature sensor and transmitting information on the sensed temperature to a controller, driving a compressor and an agitator upon determining that the temperature of the coolant reaches an upper limit temperature, and sensing a rotation speed of the agitator and transmitting information on the sensed rotation speed to the controller, wherein the controller stops the compressor at the moment of sensing deceleration of the agitator.

The method of controlling the water purifier according to the embodiment of the present invention including the above configuration has the following effects.

First, when ice is excessively generated, change in rotation speed of an agitator is sensed to control operation of a cooling cycle. Therefore, it is not necessary to install an additional component such as a temperature sensor in order to prevent ice from being excessively generated.

Second, by continuously rotating the agitator even in a state where excessive ice generation is sensed and thus the cooling cycle is stopped, cold water can be discharged even in an excessive ice control process.

Third, by continuously rotating the agitator even in a state where excessive ice generation is sensed and thus the cooling cycle is stopped, the temperature of the coolant in a coolant tank can be uniformly maintained.

FIG. 1 is an exploded perspective view of a cold water generation unit configuring a water purifier, to which a control method according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view of the cold water generation unit when an insulation case is removed.

FIG. 3 is a vertical sectional view taken along line 3-3 of FIG. 3.

FIG. 4 is a graph showing change in rotation speed of an agitator according to change in temperature of coolant.

FIG. 5 is a flowchart illustrating a method of controlling a water purifier, which is capable of preventing ice from being excessively generated, according to an embodiment of the present invention.

Hereinafter, a method of controlling a water purifier according to an embodiment of the present invention will be described in detail with reference to the drawings and flowchart.

FIG. 1 is an exploded perspective view of a cold water generation unit configuring a water purifier, to which a control method according to an embodiment of the present invention is applied, FIG. 2 is a perspective view of the cold water generation unit when an insulation case is removed, and FIG. 3 is a vertical sectional view taken along line 3-3 of FIG. 3.

Referring to FIGS. 1 to 3, the cold water generation unit 30 according to the embodiment of the present invention may include a coolant tank 33 filled with coolant, an insulation case 31 surrounding the coolant tank 33 to prevent heat exchange between the coolant and indoor air, a drain valve 32 passing through the insulation case 31 to communicate with the internal space of the coolant tank 33, a cold water pipe 34 accommodated in the coolant tank 33, a partitioner 36 accommodated in the coolant tank 33 in a state of being placed on the cold water pipe 34, an evaporator 35 placed on the partitioner 36, a tank cover 37 covering the upper end of the coolant tank 33, an agitating motor 38 fixed to the inner side of the tank cover 37 and having a rotation shaft extending downwardly, an agitator 39 accommodated in the coolant tank 33 and connected to the rotation shaft of the agitating motor 38, and a case cover 40 covering the opened upper surface of the insulation case 31.

Specifically, the drain valve 32 is installed to pass through the insulation case 31 and the coolant tank 33, and is inserted through the side surface of the insulation case 31 corresponding to a position adjacent to the bottom of the coolant tank 33. When the drain valve 32 is opened, the coolant stored in the coolant tank 33 is discharged from the water purifier 10.

In addition, the insulation case 31 is made of an insulation member such as Styrofoam and the insulation case 31 may be seated on a tank support part 21.

In addition, the cold water pipe 34 is wound in a spiral shape as shown in the figure to have a cylindrical shape, and pipes vertically adjacent to each other may be in contact with each other or spaced apart from each other. The inlet end 341 and outlet end 342 of the cold water pipe 34 may vertically extend toward the case cover 40. The inlet end 341 of the cold water pipe 34 may be connected to a water pipe connected to a water supply source and the outlet end 342 may be connected to a water pipe connected to the water outlet port of the water purifier.

In addition, the partitioner 35 is placed on the cold water pipe 34 to partition the internal space of the coolant tank 33 into a first space, in which the evaporator 35 is received, and a second space, in which the cold water pipe 34 is received. Accordingly, ice formed in the vicinity of the evaporator 35 cannot move into the second space.

In addition, the evaporator 35 is wound in a spiral shape and is seated on the outer circumferential surface of the partitioner 36. The evaporator 35 is connected to the outlet end of an expansion valve connected to the outlet end of a condenser 19. Refrigerant flowing along a refrigerant pipe forming the evaporator 35 exchanges heat with the coolant stored in the coolant tank 33, thereby cooling the coolant. The coolant exchanges heat with the drinking flowing along the cold water pipe 34, thereby cooling the drinking water to a set temperature.

The coolant may be frozen on the surface of the evaporator 35, thereby generating a lump of ice having a predetermined size. That is, cold refrigerant in the evaporator freezes the coolant, through heat absorption, such that the lump of ice accumulates latent heat of melting. That is, even in a state where the compressor 18 is not driven, coolant in an ice state and coolant in a liquid state exchange heat with each other by agitating operation of the agitator 39, such that the coolant in the liquid state is maintained at a reference temperature or less.

The water purifier according to the embodiment of the present invention may be defined as an ice thermal storage type water purifier, because some of coolant is present in an ice state on the surface of the evaporator to store latent heat. Since the ice thermal storage type water purifier may use latent heat as well as sensible heat for heat exchange, cold water discharge performance is significantly better than a non-ice thermal storage type water purifier using only sensible heat.

In addition, the tank cover 37 is provided on the upper end of the coolant tank 33, thereby covering the upper surface of the first space. That is, the first space may be defined between the tank cover 37 and the partitioner 36 and the second space may be defined between the partitioner 36 and the bottom of the coolant tank 33. A coolant inlet port 371 may be formed in one side of the tank cover 37. The coolant inlet port 371 may be connected to a water pipe connected to the water supply source to supply coolant to the coolant tank 33.

In addition, the agitator 39 may be substantially located at an intermediate point of the second space, without being limited thereto. When the agitator 39 rotates, the coolant of the second space flows into the first space to exchange heat with the evaporator 35 or the ice generated on the surface of the evaporator 35, and the coolant of the first space flows into the second space, such that the temperature of the coolant is uniformly maintained at every point of the coolant tank 33. The coolant cooled through heat exchange exchanges heat with drinking water flowing along the cold water pipe 34, thereby cooling the drinking water to a defined cold water temperature or less. Here, the defined cold water temperature may be in a range of 7°C to 8°C, without being limited thereto.

The agitator 39 may be formed in a blade or impeller shape extending from the rotation shaft in a radial direction as shown in the figure, but is not limited thereto and may be formed in various shapes.

Meanwhile, the case cover 40 is fitted on the outer circumferential surface of the upper end of the insulation case 31 to cover the opened upper surface of the coolant tank 33 and the insulation case 31. A port accommodation hole 401, through which the coolant inlet port 371 passes to be exposed to the outside, may be formed in the case cover 40. A cold water pipe guide groove 402, through which the inlet end 341 and the outlet end 342 of the cold water pipe 34 pass, may be formed in the edge of one side of the case cover 40. An evaporation pipe guide hole 403, through which the pipe of the evaporator 35 passes, may be formed in the edge of the other side of the case cover 40.

In addition, a temperature sensor (not shown) for sensing the temperature of the coolant may be installed on one side of the inside of the coolant tank 33, and the temperature sensor may include a thermistor. The temperature sensor may be placed in the first space close to the evaporator or may be placed in the second space close to the cold water pipe 34.

For example, the temperature sensor may be placed at a position relatively closer to the evaporator 35 to sense not only the temperature of the coolant but also the temperature of ice which is generated on the surface of the evaporator 35 and is in contact with the temperature sensor.

Referring to FIG. 4, when the temperature of the coolant reaches an upper limit temperature in a so-called stabilized section in which cold water is not discharged, the compressor (not shown) is driven to operate a cooling cycle.

Specifically, the upper limit temperature of the coolant for operating the cooling cycle may be differently set according to the use condition and may be, for example, set to 0.5°C without being limited thereto.

When the cooling cycle operates, 2-phase refrigerant flowing along the evaporation pipe 35 under low-temperature and low-pressure exchange heat whith the coolant stored in the coolant tank 33 to decrease the temperature of the coolant.

In addition, in a section in which the temperature of the coolant is maintained at a temperature above zero, ice is not generated and thus the number of rotation of the agitator 39 is rarely changed.

When the temperature of the coolant decreases to a freezing temperature or less, ice is generated on the surface of the evaporator and the size of the ice increases over time. When the size of the ice increases, the amount of coolant decreases and, when the amount of coolant decreases, the flow resistance of the coolant generated when the agitator rotates decreases. When the flow resistance of the coolant decreases, the rotation speed of the agitator 39 increases. In other words, while the voltage supplied to the agitating motor 38 is constantly maintained, the flow resistance applied to the agitator 38 decreases and thus the rotation speed (Hz or rpm) of the agitator 39 increases.

Meanwhile, since the evaporator 35 is wound in the spiral shape, the ice generated on the surface of the evaporator 35 is grown in a donut shape. Since the agitator 39 is disposed to pass through the inside of the evaporator 35, when ice is excessively grown, the inner edge of the ice may contact the rotation shaft of the agitator 39.

As soon as the ice contacts the agitator 39, the speed of the agitator 39 decreases due to frictional resistance of the ice. As shown in a section A of FIG. 4, when ice is excessively grown to hinder rotation of the agitator 39, an increasing speed suddenly decreases.

In addition, when the ice is continuously grown, the rotation speed of the agitator 39 rapidly decreases and the load of the agitating motor 38 rapidly increases. In this state, when operation of the cooling cycle is not stopped, overload may be applied to the agitating motor 38, thereby damaging the agitating motor 38.

The reason why the temperature of the coolant sensed by the temperature sensor is less than -12°C is as follows. Specifically, as the ice is grown, the ice contacts the temperature sensor installed on the inner circumferential surface of the coolant tank. From that instant, the temperature of the coolant in a liquid state is not sensed but the temperature of the ice in a solid state is sensed by the temperature sensor. In addition, as the operation time of the cooling cycle increases, the size of the ice generated on the surface of the evaporator increases and the temperature of the ice further decreases to less than 0°C.

The present invention is characterized in that change in speed of the agitator 39 shown in the section A is sensed to control the cooling cycle such that the ice generated in the vicinity of the evaporator 35 is prevented from being excessively grown.

Referring to FIG. 5, the method of controlling the water purifier, which is capable of preventing ice from being excessively generated, according to the embodiment of the present invention may be performed in a stabilized section in which cold water is not discharged. This is because the possibility of excessively generating ice is low when cold water is frequently discharged.

Specifically, the temperature sensor provided in the coolant tank senses the temperature of the coolant at a predetermined time interval (S11). The sensed temperature T of the coolant is transmitted to a controller (not shown) of the water purifier. The controller determines whether the sensed temperature is equal to or greater than an upper limit temperature T1. The upper limit temperature T1 may be 0.5°C as described above, without being limited thereto.

Upon determining that the temperature of the coolant is equal to or greater than the upper limit temperature, both the compressor and the agitator are driven (S13). The rotation speed R of the agitator is periodically sensed at a predetermined time interval (S14).

Meanwhile, when the compressor is driven to operate the cooling cycle, the temperature of the evaporator decreases and heat exchange between the evaporator and the coolant is performed. The temperature sensor senses and transmits the temperature T of the coolant to the controller. Then, the controller determines whether the temperature of the coolant reaches a lower limit temperature T2 (S15) and stops driving of the compressor and the agitator (S16) upon determining that the temperature T of the coolant reaches the lower limit temperature T2. The lower limit temperature T2 may be, for example, -2.5°C without being limited thereto. The upper limit temperature and lower limit temperature for driving and stopping the compressor may be appropriately set according to the predefined temperature of the coolant.

Meanwhile, the controller receives the rotation speed value from the agitator 38 until the temperature of the coolant reaches the lower limit temperature. The controller determines whether the current rotation speed R2 of the agitator is less than the previous speed R1 (S17).

Upon determining that the current speed is greater than the previous speed, this means that the ice is continuously grown. In contrast, upon determining that the current speed is less than the previous speed, it means that the ice is excessively generated to contact the agitator, thereby hindering rotation of the agitator.

Accordingly, the controller performs control to stop driving of the compressor and to continuously rotate the agitator at the moment of sensing deceleration of the agitator (S18). When the compressor and the agitator are simultaneously stopped, the coolant is not circulated such that the temperature of the coolant in the coolant tank is not uniform. In other words, the temperature of the coolant in the vicinity of the evaporator may be low but the temperature of the coolant in the vicinity of the cold water pipe may be high.

In addition, due to heat penetration from the outside, the temperature of the inner edge of the coolant tank may be relatively lower than the temperature of the central portion of the coolant tank. Then, although the ice does not melt in the central portion of the coolant tank and thus the agitator does not smoothly rotate, the temperature of the coolant sensed by the temperature sensor is sensed to be greater than the lower limit temperature and thus the cooling cycle may be driven again. Then, there is a high possibility that ice is excessively generated.

Accordingly, although excessive ice generation is sensed and thus driving of the compressor is stopped, the agitator can be controlled to continuously rotate, thereby maximizing the heat exchange effect using heat penetrating from the outside and the frictional heat between the agitator and the coolant. Then, the temperature of the coolant rapidly increases and, as a result, the ice rapidly melts, thus the phenomenon wherein ice is excessively generated can be solved in a short time. In addition, when cold water is discharged by the user during the process for controlling the excessive ice generatin, a thawing time is further shortened, thereby further shortening a time required to solve the phenomenon wherein ice is excessively generated.

In addition, since the temperature of the coolant is uniformly maintained at every point of the coolant tank by rotation of the agitator, the controller recognizes the temperature of the coolant sensed by the temperature sensor as a representative value of the coolant, thereby accurately controlling the compressor and the agitator.

Meanwhile, even in a state where the compressor stops and the agitator rotates, the temperature sensor continuously transmits the temperature value of the coolant to the controller. The controller determines whether the received temperature T of the cooling sensor reaches the upper limit temperature T1 (S19).

Upon determining that the temperature T of the coolant reaches the upper limit temperature T1, the controller drives the compressor again (S20), and periodically receives the temperature of the coolant and the rotation speed value of the agitator when the compressor is driven again and performs an excessive ice sensing process.

By sensing change in speed of the agitator to perform a control process of preventing ice from being excessively generated, it is not necessary to further install a part for preventing ice from being excessively generated, such as a temperature sensor.

Claims

A method of controlling a water purifier, the method comprising:

sensing a temperature of coolant using a temperature sensor and transmitting information on the sensed temperature to a controller;

driving a compressor and an agitator upon determining that the temperature of the coolant reaches an upper limit temperature; and

sensing a rotation speed of the agitator and transmitting information on the sensed rotation speed to the controller,

wherein the controller stops the compressor at the moment of sensing deceleration of the agitator.
The method of claim 1, wherein the agitator is controlled to be continuously rotated even when the compressor is stopped.
The method of claim 2,

wherein the compressor is driven again upon determining that the temperature of the coolant sensed by the temperature sensor reaches the upper limit temperature after the compressor is stopped, and

wherein a process of sensing the temperature of the coolant and the rotation speed of the agitator is repeatedly performed.
The method of claim 1, wherein the driving of the compressor and the agitator is stopped upon determining that the temperature of coolant reaches a lower limit temperature.
The method of claim 4,

wherein the upper limit temperature is 0.5°C, and

wherein the lower limit temperature is -2.5°C.