Description

HEATER FOR SHIP PAINTING

Technical Field

[1] The present invention relates, in general, to heaters for ship painting and, more particularly, to a heater for ship painting which has an improved structure such that temperature control and humidity control can be easily conducted, the heater can be safely operated even in unmanned conditions, and the discharge rate of heated air can be easily controlled. Background Art

[2] As well known to those skilled in the art, a process of constructing a ship is finally completed by conducting a process of painting internal and external components of the ship as well as the outer surface of the ship. Here, in the case where an outer shell of the ship, which is made of steel plates, is painted, it is necessary to create optimum temperature and humidity conditions for the painting work. The reason for this is that the optimum conditions, under which the most superior painting effect or efficiency is exhibited, exist due to the physical characteristics of the steel plates and the physical and chemical characteristics of paint.

[3] As methods of operating conventional drying apparatuses for ship painting, there are cases in which oil or gas, that is, fossil fuel, is used, and cases in which electricity is used. Recently, in consideration of the protection of environment, electric heating methods are mainly used. FIG. 1 is a view showing a representative example of the conventional drying apparatuses for ship painting. This drying apparatus 11 for ship painting was proposed in Korean Utility Model Registration No. 229848, and the main construction thereof will be explained herein below. The conventional drying apparatus 11 includes a burner 8, which uses gas as fuel, a heat generating tank 6, which has a combustion gas exhaust port 2 and receives heat supplied from the burner 8, and a heat exchange tank 16, which surrounds the heat generating tank 6 such that the inner surface of the heat exchange tank 16 is spaced apart from the outer surface of the heat generating tank 6 by a predetermined distance, so that air, which is drawn into the heat exchange tank 16, is heated by heat transferred from the outer surface of the heat generating tank 6. The conventional drying apparatus 11 further includes a blower 14, which is provided above the heat exchange tank 16 and is rotated by a drive motor 4 to forcibly supply external air into the heat exchange tank 16, a drying air outlet port 12, which discharges air that is supplied by the blower and is heated, a temperature sensor 13, which is provided to prevent the drying air outlet port 12 from being overheated, and wheels 10, which are provided on the lower end of the apparatus to

enable movement of the apparatus in the ship. However, the conventional drying apparatus for ship painting has only a function of increasing the temperature in a workplace or heating the outer steel shell of the ship to be painted without having any means for controlling the operation of the apparatus in response to the temperature and humidity in a workplace. Therefore, there are disadvantages in that work efficiency is low, and a worker must be present at the workplace in order to control the operation of the apparatus. Furthermore, other conventional drying apparatuses for ship painting also have problems in that it is difficult to control the state of heated air, for example, the temperature and the discharge rate thereof, so that the apparatuses may be easily overheated. In particular, there is a problem in that it is difficult to provide optimum humidity conditions required for the painting work. A concept of a heater having a humidity sensor and a humidifier for controlling humidity conditions was proposed in Korean Patent Application No. 10-2002-13788, which was filed on Mar. 16, 2001 and is entitled "HEATER HAVING HUMIDIFICATION DEVICE". However, the heater according to this technique is mainly used at home to cope with dry weather and maintain appropriate humidity levels. Considering the function and construction of this apparatus, it is difficult to apply the heater to the work of heating steel plates for ships before painting. Disclosure of Invention

Technical Problem

[4] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a heater for ship painting which has an improved structure such that the temperature and humidity of discharge air can be easily controlled in response to conditions in a workplace and characteristics of objects when painting a ship, thus realizing optimum painting efficiency.

[5] Another object of the present invention is to provide a heater for ship painting which is constructed such that the rate at which air is heated is relatively high and the rate at which heated air is discharged can be easily controlled when necessary, and which can be safely operated even under unmanned conditions. Technical Solution

[6] In order to accomplish the above objects, the present invention provides a heater for supplying heated air for ship painting, including: a main body for forming a basic framework of the heater; a heating unit provided at a predetermined position in the heater, the heating unit comprising a filter provided around an inlet side, an electric heater installed in a heater box to heat air, passing through the filter, and a low temperature thermostat and a high temperature thermostat mounted to the heater box; a

blower unit connected to the heating unit, the blower unit comprising an outlet port for discharging heated air, a blower fan for forcibly blowing heated air towards the outlet port, and a drive motor for supplying rotary force to the blower fan; a control unit connected to the heating unit and the blower unit to control operation of the heating unit and the blower unit; a humidity control unit, comprising a humidity sensor provided around the filter in the main body, and a humidity controller connected to the control unit; and a thermocouple provided around an outlet side of the heating unit to measure a temperature of heated air.

[7] Preferably, the electric heater may include a plurality of heating element sets arranged in an air flow direction, each of the heating element sets having fin heating elements arranged parallel to each other.

[8] Furthermore, timers may be respectively connected between the control unit and the electric heater and between the control unit and the drive motor.

[9] In addition, the control unit may have a time switch for a preprogramming operation function such that an operation beginning time on a next day is preprogrammed.

[10] The heater for ship painting may further include an air supply unit, which is provided in the heater box and is connected to an external air compressor to cool the electric heater. The air supply unit may be connected to an electronic valve.

Advantageous Effects

[11] In a heater for ship painting according to the present invention, because an electric heater includes heating element sets having multi-staged heating structures, the heat efficiency of the electric heater is markedly enhanced. Each heating element set can be independently controlled by a control unit. Therefore, a single electric heater can heat air at various temperatures. In addition, the present invention is provided with a low temperature thermostat, a high temperature thermostat and a thermocouple, so that the electric heater is prevented from overheating, thus ensuring safety in operation.

[12] Furthermore, even if emergency conditions, such as during a power failure, occur, because the heater is constructed such that the residual heat of the electric heater can be automatically removed, the safety of the heater is ensured. Hence, there is an advantage in that the heater can be operated under unmanned conditions.

[13] As well, the heater can optimally control the relative humidity in a workplace, which is one of the major factors influencing painting work, thus enhancing efficiency of the painting work, and ensuring superior quality of the painting.

[14] Moreover, in the heater of the present invention, a blower fan is disposed at a position downstream of the electric heater, so that air is discharged outside through the blower after passing through the electric heater. Thus, the heating efficiency and the heat transfer efficiency are markedly increased.

[15] In addition, the heater of the present invention has a preprogramming operation function, which makes it possible to create optimum work conditions for painting in advance. Accordingly, a worker can begin the painting work under the optimum work conditions as soon as he/she arrives at the workplace. Hence, time efficiency at work is maximized, and productivity is enhanced. Brief Description of the Drawings

[16] FIG. 1 is a view showing a representative conventional heater for ship painting;

[17] FIGS. 2 through 6 are, respectively, a plan view, a front view, a rear view, a left side view and a right side view of a heater for ship painting according to the present invention;

[18] FIGS. 7 through 10 are, respectively, a plan view, a front view, a left side view and a right side view of a heating unit according to the present invention; and

[19] FIGS. 11 through 14 are, respectively, a plan view, a front view, a rear view and a left side view of a control unit according to the present invention.

[20] <Description of the elements in the drawings>

[21] 100: heater 110: main body

[22] 120: control unit 121: control panel

[23] 126a, 126b: temperature controller 127: humidity controller

[24] 140: heater box 141: thermocouple

[25] 142: electric valve 143,144: thermostat

[26] 146: electric heater 146a: heating element set

[27] 148: filter 160: drive motor

[28] 168: outlet port

Best Mode for Carrying Out the Invention

[29] Hereinafter, the construction and operation of the present invention will be described in detail with reference to the attached drawings. FIGS. 2 through 6 are, respectively, a plan view, a front view, a rear view, a left side view and a right side view of a heater for ship painting according to the present invention. FIGS. 7 through 10 are, respectively, a plan view, a front view, a left side view and a right side view of a heating unit according to the present invention. FIGS. 11 through 14 are, respectively, a plan view, a front view, a rear view and a left side view of a control unit according to the present invention.

[30] The heater 100 of the present invention includes a main body 110, which forms the basic framework of the heater 100, a heating unit, which is disposed at a predetermined position in the main body, a blower unit, which is connected to the heating unit, a control unit 120, which controls the heating unit and the blower unit, a humidity control unit, which controls the humidity in a workplace, and a thermocouple 141,

which senses the temperature at which heated air is discharged.

[31] The main body 110 includes a base frame 110a and a side frame 110b, in which the heating unit and the blower unit are installed. Wheels 112 for movement of the heater are provided under the lower surface of the base frame 110a.

[32] The heating unit serves to heat air drawn from the outside. A filter 148 is provided in an inlet through which air is drawn into the heating unit. Air, which passes through the filter 148, is guided into the heater box 140, which has an electric heater 146 therein. As shown in FIG. 9, the electric heater 146 includes a plurality of heating element sets 146a, each of which has a plurality of individual fin heating elements 146b which are arranged in the vertical direction. The several heating element sets 146a are arranged in the direction in which air flows. In this embodiment, four heating element sets 146a are provided. Therefore, air, which is drawn via the filter 148, continuously passes through the four heating element sets 146a and is thus heated in multiple stages. As such, because the present invention is constructed such that air is heated in multiple stages, the heating efficiency or thermal efficiency thereof can be enhanced. Furthermore, each of the heating element sets 146a is independently connected to the control unit, which will be explained below, and thus each heating element set 146a can be individually controlled. Hence, there is an advantage in that it is easy to control the temperature, at which air is heated and the electric heater 146. Each heating element set 146a is connected to the control unit 120 by respective cables 123. In the drawings, the reference numeral 147 denotes a door lock of the heater box 140, 148a denotes a cover of the filter, and 124a denotes a passing hole, through which the cable 124 of electric heater 146 passes.

[33] As shown in FIG. 8, a low temperature thermostat 143 and a high temperature thermostat 144 are provided in the heater box 140. The low temperature thermostat 143 is provided to control a fan (not shown) of the blower unit such that the fan is operated at a preset temperature or more. The high temperature thermostat 144 is provided to prevent the electric heater 146 from being overheated. For example, the low temperature thermostat 143 is set such that the fan of the blower unit is rotated when the temperature in the heater box 140 is 45 ⁰ C or higher. The high temperature thermostat 144 is set such that the electric heater 146 is turned off when the temperature in the heater box 140 is 17O ⁰ C or higher. Therefore, the thermostats 143 and 144 prevent overheating of the heater 100, thus enabling the safe operation thereof even under unmanned conditions. The thermocouple 141 is provided around an outlet of the heater box 140 to measure the temperature of heated air that is discharged from the outlet of the heater box 140. A flange 145 for connection with the blower unit, which will be explained later herein, is provided on the outlet of the heating unit.

[34] In the present invention, the electric heater 146 in the heater box 140 can be operated

in an unmanned or manned manner under the control of the control unit 120, which will be described later herein. Under emergency conditions, such as during a power failure, it is necessary to remove residual heat from the electric heater 146, which has been heated at a high temperature. That is, because the blower unit is stopped under certain conditions, such as during a power failure, it is preferable that a separate air supply unit (not shown), which supplies compressed air into the heater box 140, be provided such that the electric heater 146 can be cooled even under such conditions. The air supply unit is constructed such that it is controlled by an electronic valve 142. Therefore, under normal conditions, the electronic valve 142 maintains a closed state. Under conditions such as during a power failure, the electronic valve 142 is opened, so that cooling air is supplied into the heater box 140 from an external air compressor or the like. The air supply unit may have a nozzle type structure, which is connected to the external air compressor through a hose. In this case, the air passage of the nozzle is controlled by the electronic valve 142. That is, under normal conditions, the air passage of the nozzle maintains the state of having been closed by the electronic valve 142. Under conditions such as during a power failure, the electronic valve 142 is opened, thus opening the air passage of the nozzle.

[35] The blower unit serves to discharge heated air towards a working object or space in the workplace. The blower unit is connected to the heating unit through a connection pipe 165, such as a bellows pipe. Heated air is drawn into the blower unit by the rotating force of the fan (not shown) of the blower and is discharged outside through an outlet port 168, which has a duct shape. The blower fan is connected to a drive motor 160 using a connection belt 162 and is thus rotated by the operation of the drive motor 160. In the drawings, the reference numeral 161 denotes a belt pulley, 163 denotes a casing for the blower fan, 167 denotes a rotating shaft, 169 denotes a bearing, and 170 denotes a vibration isolation pad. The blower fan (not shown) is disposed in the casing 163 of the blower.

[36] The control unit 120 is connected to the heating unit and the blower unit and thus controls the operation of the heater 100. A plurality of control switches is provided on a control panel 121 of the control unit 120. The intended purposes of the switches are as follows. The reference numerals 126a and 126b denote temperature controllers, 127 denotes a humidity controller, 128 denotes an emergency stop switch, 129 denotes a preprogramming operation time switch, 130 denotes an automatic/manual mode selection switch, 131a denotes a blower fan start switch, 131b denotes a blower fan stop switch, 132 denotes an electric heater reset switch, and 133 denotes an electric heater control switch. Furthermore, the reference numeral 122 denotes a side door of the control unit, 122a denotes a side door lock, 123 denotes a control unit upper door, 123 a denotes an upper door lock, and 125 denotes a cable connector.

[37] The humidity controller 127 functions to provide an optimum environment for the painting work and, particularly, to maintain the humidity in the indoor workplace to a degree suitable for the painting work. In detail, a humidity sensor, which is connected to the control unit 120, is provided around the inlet of the heating unit. Depending on the relative humidity measured by the humidity sensor, the control unit 120 operates the electric heater 146 and the drive motor 160, thus controlling the relative humidity in the workplace. Typically, ships are constructed in workplaces in coastal areas, which are relatively high in humidity. Hence, whether the painting work is satisfactory or not is greatly affected by the control in humidity. In the case where the humidity controller 127 and the humidity sensor of the present invention are used, the relative humidity in the workplace can be easily controlled, thus enhancing painting efficiency. The humidity controller 127, which is connected to the control unit 120, controls the heater 100 depending on a relative humidity value measured by the humidity sensor such that the heater 100 is operated until the relative humidity in the workplace reaches a reference relative humidity value, which is preset in the humidity controller 127. When the relative humidity in the workplace reaches the reference relative humidity value, the control unit 120 appropriately controls the heating rate of the electric heater and the rpm of the blower fan, thus maintaining the temperature and humidity in the workplace constant.

[38] Meanwhile, separate timers (not shown) are respectively connected between the control unit 120 and the electric heater 146 and between the control unit 120 and the drive motor 160, so that the time for which the electric heater 146 or the drive motor 160 is operated can be controlled by the control unit 120. For example, it is preferable that the electric heater 146 start operating five minutes after the time at which the rotation of the blower fan starts. This time gap in commencement of operation between the electric heater 146 and the blower fan is set by the timers. Furthermore, in the present invention, the preprogramming operation time switch 129 is provided in the control unit 120. Thus, the operation of the heater 100 can be started at a desired time by setting the operation start time using the preprogramming operation time switch 129. For example, if a worker, when leaving his/her work sets the preprogramming operation time such that the heater 100 starts operating about two hours before a work beginning time the next day, because the humidity and temperature in the workplace can be controlled in advance to be suitable for the painting work the next day, the worker can begin the painting work as soon as he/she arrives at work the next day. Hence, the painting work can be efficiently and economically implemented.

[39] The heater 100, which has been described above, has an air heating and supply structure different from that of the conventional techniques. That is, unlike the conventional techniques, in which air supplied from the rear of the electric heater is heated

while passing through the electric heater and is discharged, the heater 100 of the present invention has a structure in which the blower unit is disposed at a position subsequent to the electric heater 146 in the air flow path. In other words, the present invention is constructed such that air drawn by the rotation of the blower fan is discharged outside through the outlet port 168 after passing through the filter 148 and the multi-stage electric heater 146. This structure of the present invention is advantageous in that the efficiency with which air is heated is markedly enhanced.