Abstract:
The present invention relates to a portable boiler for a hot mat, which comprises: a water reservoir, one side of which has an inlet pipe for introducing water circulating through the hot mat, and which stores the water; a heat transfer unit in which the water discharged from the water reservoir flows along a flow channel pipe to be heat exchanged, wherein the water is discharged to the hot mat via an outlet pipe formed at one side thereof; a heating unit which burns the fuel gas fed from a fuel tank to heat the water in the heat transfer unit; and a housing which forms the outer appearance of the boiler.

Description:
TECHNICAL FIELD 
     The present invention relates to a portable boiler for a heating mat, and more particularly, to a portable boiler for a heating mat, which heats and circulates circulating water in the mat to maintain the mat at a desired temperature during camping for enjoying fishing and climbing at an outdoor place such as mountain, riverside, and seashore. 
     BACKGROUND ART 
     Generally, tents or sleeping bags are used for camping at outdoor places such as mountain, riverside, and seashore for climbing and fishing. 
     In this case, people lay a plastic or vinyl mat on the ground to interrupt chill and moisture from the ground. 
     Nevertheless, it is difficult to maintain the body temperature in a situation of severe cold such as winter climbing or alpine climbing. Unless the body temperature is appropriately maintained during camping, judgment and ability to cope with a crisis may be affected, causing a serious accident. 
     In order to overcome the above problems, Korea Utility Model Registration No. 207,192 and Korea Patent Registration No. 604,405 disclose a water heater for a heating mat and a portable boiler, respectively. However, since the water heater for the heating mat and the portable boiler do not include a separate temperature controller for controlling the temperature of circulating water that circulates in a heating mat and a hot water floor mat, a user may be burned by the circulating water of increasing temperature. 
     Also, since gas bubbles of high pressure generated during heating of the circulating water cannot be discharged and circulate along a pipe and a hot water hose together with the circulating water, the gas bubbles may hit against the inner surface of the pipe and the hot water hose, causing a noise. 
     DETAILED DESCRIPTION 
     Technical Problems 
     The present invention seeks to solve the above-mentioned problems, and provides a portable boiler for a heating mat, which can prevent a noise during circulation of circulating water in the heating mat and can selectively control the temperature of the circulating water. 
     The present invention also provides a portable boiler for a heating mat, which has a stable structure of using a portable fuel gas can that can be carried during camping such as climbing. 
     Technical Solutions 
     Embodiments of the present invention provide portable boilers for a heating mat, including: a water reservoir storing circulating water that is received through an inlet tube disposed on one side of an upper portion of the water reservoir; a heat-transfer part allowing the circulating water to flow along a flow passage to exchange heat and discharging the circulating water to the heating mat through an outlet tube disposed on one side of the heat-transfer part; a heating part for heating the circulating water inside the heat-transfer part by burning fuel gas supplied from a fuel tank; and a housing defining an exterior of the portable boiler, wherein: the water reservoir includes: the inlet tube connected to one and of a circulation pipe buried in the heating mat on the one side of the upper portion of the water reservoir; a fixing bracket having a plurality of holes to allow the circulating water to flow into the heat-transfer part; a check valve formed of a thin film and opening/closing the plurality of holes according to a water pressure of the circulating water; and a temperature sensor sensing a temperature of the circulating water to generate a physical signal using expansion and contraction of a liquid filled therein; the heat-transfer part has the flow passage that allows the circulating water to absorb heat when the check valve is opened and the circulating water flows therein; and the heating part includes: a gas controller for controlling an injection amount of the fuel gas supplied from the fuel tank; a controller receiving the physical signal from the temperature sensor to control the gas controller; and an igniter including a combustor for burning the fuel gas supplied from the gas controller and a spark plug generating an electric spark on the combustor. 
     In some embodiments, the portable boiler may further include a heat-collecting plate on an undersurface of the heat-transfer part to increase thermal conductivity. 
     In other embodiments, the portable boiler may further include a plurality of heat-collecting fins radially disposed from a center of the heat-collecting plate to the outside. 
     In other embodiments, the gas controller may include: a coupling part coupled to the fuel tank; a support block including a first fuel discharging tube allowing the fuel gas supplied from the fuel tank to be ejected through a first fuel discharging hole; a first cylinder assembly mounted with a first piston that moves in a cylinder due to a rotation of a control knob screwed into a control screw part formed in the cylinder to open and close the first fuel discharging tube, and disposed on the support block to communicate with the first fuel discharging tube; and a second cylinder assembly mounted with a second piston that moves slidably moves in a cylinder to open and close a second fuel discharging tube, and disposed on the support block to communicate with the first cylinder assembly and discharge the fuel gas received through the second discharging tube; the controller may include: a movement member abutting on an end portion of the second piston of the second cylinder assembly to move the second piston by expanding or contracting due to the physical signal generated by the temperature sensor; and a location controller for controlling a location of the movement member; the combustor may burn the fuel gas received through the second fuel discharging hole of the second cylinder assembly; and the igniter may include the spark plug generating the electric spark on the combustor. 
     In still other embodiments, the flow passage of the heat-transfer part may include: a vertical flow passage to which the circulating water first flows through the check valve of the water reservoir; a bypass flow passage detouring the circulating water from the vertical flow passage to one side; an inclination flow passage communicating with the bypass flow passage and inclining toward the outlet tube. 
     In even other embodiments, the portable boiler may further include a space part defined by a support bracket disposed between the flow passage and the heat-collecting plate of the heat-transfer part to support the flow passage and the heat-collecting plate of the heat-transfer part. 
     In yet other embodiments, the portable boiler may further include a shield plate disposed between the inclination flow passage and the bypass flow passage of the heat-transfer part to prevent heat transferred from the heat-collecting plate from being transferred to the water reservoir through the flow passage. 
     In further embodiments, the check valve may be formed using a flexible silicon thin-film and may be coupled to one end of a rise and fall rod penetrating a center of the fixing bracket, and an elastic member may be disposed around an outer circumferential surface of the rise and fall rod and may be supported by the other end of the rise and fall rod and the fixing bracket. 
     In still further embodiments, the temperature sensor may include: a signal generation part submerged in the water reservoir and generating a physical signal that allows expansion and contraction using a liquid filled therein when the temperature of the circulating water loaded in the water reservoir reaches a certain temperature; and a signal delivery part including a capillary tube filled with the liquid to deliver the physical signal to the movement member. 
     In even further embodiments, the fixing bracket may have an ejection hole for discharging vapor generated when the circulating water flows in the heat-transfer part and may include an air ejector that opens the ejection hole when a pressure of the vapor becomes greater than a certain pressure. 
     In yet further embodiments, the portable boiler may further include a pressurizing member that has a rod shape and allows the rise and fall rod to be manually pushed from the outside. 
     In much further embodiments, the housing may have a plurality of first air passages at a location of an outer circumferential surface thereof corresponding to the bypass flow passage of the heat-transfer part in an outer circumferential surface of the housing and a plurality of air passages at a location of the outer circumferential surface thereof corresponding to the heat-collecting plate. 
     In still much further embodiments, the portable boiler may further include an auxiliary cover in the housing corresponding to the first air passages. Here, the auxiliary cover has a plurality of auxiliary air passages that selectively open and close the first air passages. 
     In even much further embodiments, the portable boiler may further include a windproof plate outside the housing corresponding to the second air passages, the windproof plate preventing a direction of a flame from being biased according to a flow of air received through the second air passages. 
     In even much further embodiments, the second piston of the second cylinder assembly may have a recessed groove on a front end thereof such that a very small amount of fuel flows into the second cylinder assembly even when the fuel discharging tube of the second cylinder assembly is closed, and the second fuel discharging tube of the second cylinder assembly may have a recessed groove in an inner circumferential surface thereof such that a very small amount of fuel flows into the second cylinder assembly even when the fuel discharging tube of the second cylinder assembly is closed. 
     In yet much further embodiments, the location controller may include: an elastic frame supporting the movement member while being fixed on one side of the support block; a fixing frame coupled to the other side of the support block, and a location control lever including a control bolt penetrating the fixing frame and screwed into the elastic frame at one end thereof, and a grip for rotating the control bolt at the other end thereof, and a control nut may be further provided between the fixing frame and the elastic frame to be coupled to the control bolt and be fixed on the elastic frame. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating the exterior of a portable boiler for a heating mat and the heating mat according to an exemplary embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating the overall structure of a portable boiler for a heating mat according to an exemplary embodiment of the present invention; 
         FIG. 3  is an exploded perspective view illustrating a fixing bracket, a rise and fall rod, a check valve, and an air ejector, which are mounted on a water reservoir according to an exemplary embodiment of the present invention; 
         FIG. 4  is a perspective view illustrating a configuration of a heat-transfer part according to an exemplary embodiment of the present invention; 
         FIG. 5  is a front view illustrating the exterior of a heating part according to an exemplary embodiment of the present invention; 
         FIG. 6  is a cross-sectional view taken along line I-I, which illustrates an interaction between a temperature sensor and a heating part according to an exemplary embodiment of the present invention; 
         FIGS. 7 and 8  are schematic views illustrating a recessed groove formed in a second piston and a second fuel discharge pipe according to an exemplary embodiment of the present invention. 
     
    
    
     BEST MODES FOR PRACTICING INVENTION 
     Exemplary embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     These embodiments and the drawings are not intended to limit the technical scope of the present invention but to facilitate a better understanding of the present invention. 
       FIG. 1  is a schematic view illustrating the exterior of a portable boiler for a heating mat and the heating mat according to an exemplary embodiment of the present invention. 
     A portable boiler  1000  for a heating mat  10  includes a water reservoir  100 , a heat transfer part  200 , a heating part  300 , and a housing  700 . The water reservoir  100  stores circulating water. An inlet tube  110  is formed on one side of the upper portion of the water reservoir  100  to receive the circulating water that circulates in the heating mat  10 . The circulating water discharged from the water reservoir  100  flows along a flow passage to perform heat-exchange, and then may be discharged into the heating mat  10  through an outlet tube  210  disposed on one side of the heat-transfer part  200 . The heating part  300  heats the circulating water inside the heat-transfer part  200  by burning a fuel gas supplied from a fuel tank T. The housing  700  defines the exterior of the portable boiler  1000 . The circulating water discharged from the heating mat  10  flows into the portable boiler  1000  through the inlet tube  10 , and is heated during the flowing along the flow passage. Thereafter, the circulating water is again discharged into the heating mat  10  through the outlet tube  210 . 
     Although not shown in  FIG. 1 , the portable boiler  1000  further includes a temperature sensor  140 , a gas controller  400 , and a controller  500 . The temperature sensor  140  senses the temperature of the circulating water to generate a physical signal using expansion and contraction of a liquid filled therein. The gas controller  400  controls an injection amount of the fuel gas supplied from the fuel tank. The controller  500  receives the physical signal from the temperature sensor  140  to control the gas controller  400 . 
     A wrinkled part  760  is formed on the housing  700  corresponding to the water reservoir  100  to facilitate the cooling of the circulating water flowing into the water reservoir  100  and reinforce the strength of the housing  700 . 
     A plurality of first air passages  710  are disposed in the outer circumferential surface of the housing  700  corresponding to a location of a bypass flow passage  205  of the heat-transfer part  200 . The plurality of first air passages  710  supply air to perform air-cooling such that the bypass flow passage  205  and a vertical flow passage  203  of the heat-transfer part  200  are not overheated by heat transferred from an inclination flow passage  207 . 
     A plurality of second air passages  720  are disposed on a location corresponding to a heat-collecting plate  250 . The plurality of second air passages  720  discharge gases and heat generated during the combustion of the fuel gas triggered by an igniter  600  described later. 
     When the air flow rate through the second air passages  720  is excessively high, the direction of flame is biased according to the air flow. Accordingly, a windproof plate  750  is further provided to prevent the above limitation. 
     An auxiliary cover  740  is mounted in the housing  700  corresponding to the first air passages  710 . The auxiliary cover  740  has a plurality of auxiliary air passages  743  formed therein to selectively open and close the first air passages  710 . The auxiliary cover  740  may serve to prevent reduction of the thermal efficiency when the temperature of the heat-transfer part  200  is excessively reduced due to external air of significantly low temperature received through the first air passages  710 . 
     The auxiliary cover  740  having the auxiliary air passages  743  is used by appropriately adjusting a location thereof relative to that of the first air passages  710  according to the surrounding environment. 
     Hereinafter, the structure and operation of the portable boiler for the heating mat of  FIG. 1  will be described in more detail with reference to  FIGS. 1 through 6 . 
       FIG. 2  is a cross-sectional view illustrating the overall structure of a portable boiler for a heating mat according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 2 , the housing  700  defining the exterior of the portable boiler houses the water reservoir  100 , the heat-transfer part  200 , and the heating part  300  from top to bottom. Although shown as partitioned into three parts, the housing  700  is formed using one member as a whole. 
     The water reservoir  100  includes an inlet tube  110 , a fixing bracket  120 , a check valve  130 , and a temperature sensor  140 . The inlet tube  110  is disposed on the right upper portion of the water reservoir  100  to be connected to one end of the circulation pipe  20  buried in the heating mat  10 . The fixing bracket  120  has a plurality of holes  123  to allow the circulating water to flow into the heat-transfer part  200 . The check valve  130  may open and close the plurality of holes  123  according to a water pressure of the circulating water. The check valve  130  is formed of a flexible silicon thin-film. The temperature sensor  140  senses the temperature of the circulating water to generate a physical signal using expansion and contraction of a liquid filled therein. The check valve  130  is coupled to one end of a rise and fall rod  124  penetrating the center of the fixing bracket  120 . Also, a spring is provided on the outer circumferential surface of the rise and fall rod  124  that are supported by the other end of the rise and fall rod  124  and the fixing bracket  120 . Although the spring  125  is exemplified in the present embodiment, other elastic members that can be restored when a compressive force is removed may be used. 
     To explain the operation of the water reservoir  100 , it will be assumed that circulating water is not included at all in the water reservoir  100  at the initial stage. 
     When an upper cover forming a portion of the housing  700  is opened and then circulating water is inputted, the check valve  130  has to be opened to allow the circulating water to flow into the heating mat  10  through the outlet tube  210 . Since the check valve  130  is formed of a silicon thin film, the check valve  130  is closed until the circulating water received in the water reservoir  100  have a certain water pressure. Accordingly, the rise and fall rod  120  may be manually moved downward. The spring  125  is wound around the outer circumferential surface of the rise and fall rod  124 , and the both ends thereof are supported by the one end of the rise and fall rod  124  and the fixing bracket  120 . Accordingly, when a compressive force is removed, the rise and fall rod  124  may move upward to close the check valve  130 . 
     In this case, the gas fuel supplied from the fuel tank T needs not to be ignited. 
     The check valve  130  is forcibly opened for a certain time to allow the circulating water to flow into the heating mat  10 . When the rise and fall rod  124  is released, the check valve  130  is opened and closed only by the water pressure of the circulating water including in the water reservoir  100 . When the check valve  130  is opened, the circulating water discharged through the holes  123  formed in the fixing bracket  120  flows into the heat-transfer part  200 . 
     Hereinafter, the fixing bracket  120 , the rise and fall rod  124 , the check valve  130 , and an air ejector  127  will be described in detail with reference to  FIG. 3 . 
       FIG. 3  is an exploded perspective view illustrating the fixing bracket  120 , the rise and fall rod  124 , the check valve  130 , and the air ejector  127  that are mounted in the water reservoir  100 . 
     As shown in  FIG. 3 , the holes  123  having a certain depth are radially formed in the fixing bracket  120 . When the check valve  130  is opened, circulating water flows through a hollow space of the fixing bracket  120 . A female screw is disposed under the fixing bracket  120  to couple the fixing bracket  120  to the vertical flow passage  203  of the heat-transfer part  200 . 
     The check valve  130  is disposed under the holes  123  of the fixing bracket  120  to allow the holes to be opened when the check valve  130  sinks down due to the water pressure of the circulating water included in the water reservoir  100 . 
     In this case, a rubber packing  128  is disposed under the fixing bracket  120  to prevent a water leakage between the fixing bracket  120  and the heat-transfer part  200 . 
     A stepped hole is formed in the center of the fixing bracket  120  to allow the rise and fall rod  124  to penetrate therethrough. One end of the spring  125  wound around the outer circumferential surface of the rise and fall rod  124  is supported by the stepped portion. 
     As described above, the rise and fall rod  124  is used to load circulating water at the initial stage of the operation. When the rise and fall rod  124  is pushed, the check valve  130  coupled to the end portion of the rise and fall rod  124  is forcibly opened. When the pushing force is removed, the check valve  130  is again closed by a resilient force of the spring  125 . 
     An ejection hole  126  is further formed in an outermost portion of the fixing bracket  120 . The air ejector  127  is screwed into the ejection hole  126 . 
     The ejection hole  126  of the air ejector  127  is provided to discharge vapor generated during flowing of the circulating water in the heat-transfer part  200 . When the vapor has a certain pressure, the vapor pushes up a ball blocking the ejection hole  126  to be discharged into the water reservoir  100  through an air outlet  127   a.    
     Since vapor generated from the heat-transfer part  200  is compressible unlike water, the vapor has to be removed because of small volume but high pressure. Thus, noise and danger of explosion generated during the circulation along the heating mat  10  can be prevented. 
     Although not shown, a pressurizing member having a rod shape is further disposed such that the rise and fall rod  124  can be manually pushed from the outside. The pressurizing member may abut on the head of the rise and fall rod  124 . 
     Hereinafter, a configuration of the heat-transfer part  200  will be described in more detail with reference to  FIG. 4 . 
       FIG. 4  is a perspective view illustrating the configuration of the heat-transfer part  200 . 
     As shown in  FIG. 4 , the flow passage  220  is provided in the heat-transfer part  200  to allow the circulating water to absorb heat when the check valve  130  of the water reservoir  100  is opened and the circulation water flows therethrough. 
     The water passage  220  includes a vertical flow passage  203 , a bypass flow passage  205 , and an inclination flow passage  207 . The vertical flow passage  203  first receives the circulating water through the check valve of the water reservoir  100 . The vertical flow passage  203  includes a male screw that is coupled to the lower end of the fixing bracket  120  of the water reservoir  100  through a screw-coupling. The bypass flow passage  205  detours the circulating water received from the vertical flow passage  203  to one side. The inclination flow passage  207  communicates with the bypass flow passage  205 , and has an inclined flow passage toward the outlet tube  210 . 
     The bypass flow passage  205  prevents air bubbles generated by a sudden vaporization of the circulating water received from the vertical flow passage  203  when the circulating water vertically drops on the bottom heated at a high temperature. 
     Also, the inclination flow passage  207  toward the outlet tube  210  increases a heat-transfer area and prevents a sudden vaporization of the circulating water, thereby facilitating the circulation of the circulating water. 
     A heat-collecting plate  250  having a circular shape is attached to the undersurface of the heat-transfer part  200  to increase the thermal conductivity from the heating part  300  to the flow passage  220 . The heat-collecting plate  250  includes a plurality of heat-collecting fins  255  that are radially disposed from the center of the heat-collecting plate  250  to the outside. 
     A support bracket  230  is disposed between the flow passage  220  (inclination flow passage  207  to be exact) and the heat-collecting plate  250  to support the flow passage  220  (inclination flow passage  207  to be exact) and the heat-collecting plate  250 . The support bracket  230  secures a space part  240  between the heat-collecting plate  250  and the flow passage  220 . Thus, heat transfer from the heat-collecting plate  250  to the flow passage  220  is achieved by convection through the space part. Heat transfer from the heat-collecting plate  250  to the upper portion of the inclination flow passage  207  is achieved by conductivity through the support bracket  230 . Since the support bracket  230  extends from the upper portion of the inclination flow passage  207 , the thermal transfer at the bottom of the inclination flow passage  207  is performed by convection through the space part  240 . Accordingly, a sudden vaporization that is generated on the bottom of the inclination flow passage  207  is prevented in advance. 
     A shield plate  260  is disposed between the inclination flow passage  207  and the bypass flow passage  205  of the heat-transfer part  200  to prevent heat transferred from the heat-collecting plate  250  from being transferred to the water reservoir  100  through the flow passage  220 . The shield plate  260  prevents the temperature of the circulating water entering the heating mat  10  from rising above a desired temperature when the circulating water inside the water reservoir  100  is heated by the heat-transfer part  200 . 
     Hereinafter, a mechanism of sensing the temperature of the circulating water loaded in the water reservoir  100  and controlling the amount of fuel gas supplied from the fuel tank T according to the temperature of the circulating water will be described in detail with reference to  FIGS. 5 and 6 . 
       FIG. 5  is a front view illustrating the exterior of the heating part  300 . 
     As shown in  FIG. 5 , the heating part  300  includes a gas controller  400 , a controller  500 , and an igniter  600 . The gas controller  400  adjusts an ejection amount of fuel gas supplied from the fuel tank T. The controller  500  receives a physical signal of expansion or contraction generated from the temperature sensor  140  to control the gas controller  400 . The igniter  600  includes a combustor  610  for burning fuel gas received through a second fuel discharging hole  414   a  of a second cylinder assembly  430 , and a spark plug  620  for generating an electric spark on the combustor  610 . 
       FIG. 6  is a cross-sectional view taken along line I-I, which illustrates an interaction between the temperature sensor  140  and the heating part  300 . 
     As shown in  FIG. 6 , the temperature sensor  140  may include a signal generation part  143  and a signal delivery part  145 . The signal generation part  143  is disposed in the water reservoir  100 , and senses the temperature of the circulating water loaded in the water reservoir  100  to generate a physical signal by expansion or contraction of a liquid filled therein according to the temperature of the circulating water. The signal delivery part  145  is formed using a capillary tube to deliver the physical signal generated by the signal generation part  143  to the controller  500  (a movement member  510 ) of the heating part  300 . 
     The physical signal generated in the signal generation part  143  refers to an expansive force or a contractile force of a liquid filled in the signal generation part  143 . Accordingly, when the temperature of the circulating water in the water reservoir  100  rises above a certain temperature, the liquid filled therein may expand to deliver an expansive force to the movement member  510 . Due to the expansion of the movement member  510 , a second piston  431  moves to the left side on the drawing, closing a second fuel discharging tube  414 . 
     On the other hand, based on the principle that the specific volume of a liquid is reduced when the temperature of the circulating water in the water reservoir  100  becomes smaller than a certain temperature, a second fuel discharging tube  414  is opened. This is because the pressure of fuel gas from the first cylinder assembly  420  to the second fuel discharging tube  414  moves the second piston  431  to the left side of the drawing. 
     Since the signal delivery part  145  is formed using a capillary tube, a fine change of the specific volume of the liquid is changed into a change of the pressure to be delivered to the movement member  510 . 
     The liquid filled in the temperature sensor  140  is not limited to a specific material. For example, if there is a change of the specific volume according to the temperature thereof, other materials can be applied. 
     Hereinafter, the configuration of the heating part  300  will be described in detail with reference to  FIG. 6 . 
     The gas controller  400  includes a support block  410 , a first cylinder assembly  420 , and a second cylinder assembly  430 . The support block  410  includes a coupling part  411  coupled to the fuel tank T, and a first fuel discharging tube  413 . The fuel gas supplied from the fuel tank T is ejected through a first fuel discharging hole  413   a  of the first fuel discharging tube  413 . The first cylinder assembly  420  includes a first piston  421  opening and closing the first fuel discharging tube  413  by moving in the cylinder due to a rotation of a control knob  440  that is screwed into a control screw part  422  formed in the cylinder. The first cylinder assembly  420  is disposed on the support block  410  to communicate with the first fuel discharging tube  413 . The second cylinder assembly  430  includes a second piston  431  for opening and closing the second fuel discharging tube  414  by slidably moving therein and is formed on the support block  410  to communicate with the first cylinder assembly  420 . The second cylinder assembly  430  has the second discharging hole  414   a  for discharging the fuel gas received through the second fuel discharging tube  414 . 
     The first and second assemblies  420  and  430  are disposed on the support block  414 . 
     The cylinder assemblies  420  and  430  includes the first and second fuel discharging tubes  413  and  414 , the first and second fuel discharging holes  413   a  and  414   a , and the first and second pistons  421  and  431 , respectively. 
     The first cylinder assembly  420  manually controls the amount of fuel gas ejected from the fuel tank T. The first cylinder assembly  420  controls the opening degree of the first fuel discharging tube  413  using movement of the first piston  421  due to the rotation of the control knob  440  that is screwed into the control screw part  422  formed in the cylinder. 
     On the other hand, the second cylinder assembly  430  controls the amount of fuel gas necessary to heat the heat-transfer part  200 . The second cylinder assembly  430  sends the fuel gas to the combustor  610  of the igniter  600 . 
     Since the second cylinder assembly  430  communicates with the first cylinder assembly  420 , the fuel gas from the first cylinder assembly  420  enters the second cylinder assembly  430  through the second fuel discharging tube  414  and the second fuel discharging tube  414   a  thereof. 
     The opening degree of the second fuel discharging tube  414  is determined by the movement of the second piston  431  of the second cylinder assembly  430 . The movement of the second piston  431  is performed the expansion and contraction of the movement member  510  that expands or contracts according to the physical signal generated from the temperature sensor  140 . 
     In this case, since the movement member  510  abuts on the end of the second piston  431 , the second piston  431  moves the left side of the drawing to close the second fuel discharging tube  414  due to the expansion of the movement member  510 , or moves the right side of the drawing to open the second fuel discharging tube  414  due to the contraction of the movement member  510 . Since the fuel gas discharged from the first cylinder assembly  420  moves the second piston  431  to the right side of the drawing at a certain pressure through the second fuel discharging tube  414 , the end of the second piston  431  and the movement member  510  may move to the right side of the drawing while maintaining an abutting state therebetween. 
     Hereinafter, a configuration of the controller  500  will be described in more detail with reference to  FIG. 6 . 
     As shown in  FIG. 6 , the controller  500  includes the movement member  510  and a location controller  550  for manually controlling the location of the movement member  510 . 
     The location controller  550  manually controls the opening degree of the second fuel discharging tube  414  of the second cylinder assembly  430 . The location controller  550  includes an elastic frame  520 , a fixing frame  530 , a location control lever  540 , and a control nut  521 . The elastic frame  520  supports the movement member  510  while being fixed on one side of the support block  410 . The fixing frame  530  is coupled to the other side of the support block  410 . The location control lever  540  penetrates through the fixing frame  530  and include a control bolt  541  screwed to the elastic frame  520  at one side thereof, and includes a grip  542  for rotating the control bolt  541  at the other side thereof. The control nut  521  is coupled to the control bolt  541  between the fixing frame  530  and the elastic frame  520 , and is fixed on the elastic frame  520 . 
     As shown in  FIG. 6 , since the elastic frame  520  is fixed on only one side of the support block  410  and be coupled to the movement member  510 , the movement member  510  moves together with the elastic frame  520  when the elastic frame  520  moves in a lateral direction. 
     The fixing frame  530  is fixed on the other side of the support block  410  in an L-shape. The control bolt  541  of the location control lever  540  is screwed into the elastic frame  520  through the fixing frame  530  at a location where the fixing frame  530  and the elastic frame  520  face each other at the shortest distance. 
     When the grip  542  of the location control lever  540  rotates in the fastening direction of the screw, the location control lever  540  cannot move upward due to the fixing frame  530 . Accordingly, the control nut  521  and the elastic frame  520  fastened to thereto moves to the left side of the drawing. 
     In this case, the control nut  521  is selectively used to reinforce the use strength. Although the control nut  521  is not provided, it is possible to obtain the same operational effect. 
     When the initial location of the movement member  510  is set by operating the location controller  550 , the opening degree of the second fuel discharging tube  414  of the second cylinder assembly  430  is determined. Thereafter, the movement member  510  is moved by a physical signal of the temperature sensor  140 , and thus the opening degree of the second fuel discharging tube  414  is controlled by the second piston  431 . 
     When the temperature of the circulating water loaded in the water reservoir  100  reaches a predetermined temperature, the movement member  510  is expanded by an expansion signal of the temperature sensor  140  to push the second piston  431 , allowing a very small amount of fuel gas to flow into the igniter  600  through the second fuel discharging hole  414   a  even when the second fuel discharging tube  414  is completely closed, thereby enabling the maintenance of the temperature of the circulating water. Hereinafter, a detailed description thereof will be made with reference to  FIGS. 7 and 8 . 
     As shown in  FIG. 7 , a recessed groove  431   a  is formed in the front end of the second piston  431  of the second cylinder assembly  430  such that a very small amount of fuel can flow into the second cylinder assembly  430  even when the fuel discharging tube  414  of the second cylinder assembly  430  is closed. Thus, even when the fuel discharging tube  414  of the second cylinder assembly  430  is completely closed, a very small amount of fuel gas flows into the second cylinder assembly  430  through the recessed groove  431   a , thereby enabling fuel gas necessary for maintenance of the temperature of the circulating water to be sent to the igniter  600 . 
     Alternatively, as shown in  FIG. 8 , a recessed groove  414   b  may also be formed in the inner circumferential surface of the fuel discharging tube  414  of the second cylinder assembly  430  such that a very small amount of fuel can flow into the second cylinder assembly  430  even when the fuel discharging tube  414  of the second cylinder assembly  430  is closed. 
     The exemplary embodiments of the portable boiler  1000  for the heating mat  10  have been described to facilitate a better understanding of the present invention, and should not be construed as limiting the technical scope of the present invention. 
     Also, it will be understood by those skilled in the art that the exemplary embodiments of the present invention can be modified and changed without deviating from the technical spirit of the present invention. 
     For example, the type of the liquid filled in the temperature sensor  140 , the shape or material of the movement member  510 , the combination structure of the respective components, and the shape and material of the flow passage included in the heat-transfer part  200  set forth herein should not become criteria that determine the technical scope of the present invention, rather the scope of the present invention should be determined only by claims described later.