KR100382230B1 - Industrial heater and heating roll for image formating device - Google Patents

Abstract

The present invention, the rapid heating with the main heating source installed in the container until the surface temperature of the container reaches a certain level, and then continuously maintains the surface temperature at the target temperature with the auxiliary heating source installed outside the container. It relates to a heat pipe heater and an image fixing apparatus using the same.

Heat pipe type heater according to an embodiment of the present invention is a metal container, a working fluid to be filled in the container in a negative pressure state, and is built in the container and at the same time acts as a return path of the working fluid The main heating source that heats the working fluid to rapidly raise the surface temperature of the container to a certain temperature through the phase change of the fluid, and compensates the amount of heat radiated from the container to maintain the surface temperature at a constant temperature An auxiliary heating source to be maintained and a temperature control unit that operates in response to the change in the internal pressure of the container.

Description

Heat pipe type heater and image fixing device using the same {Industrial heater and heating roll for image formating device}

The present invention relates to a heat pipe type heater used in an industrial facility such as a boiler, a snow removal device, and an automatic choke, and an image fixing device using the same.

More specifically, a small resistance main heating source installed in the container until the surface temperature of the metal container (hereinafter referred to as container) reaches a target temperature by rapidly raising the surface temperature of the container at the beginning of startup. And heat pipe type to continuously maintain the surface temperature of the container at a target level by compensating with a large resistance auxiliary heating source installed on the outside of the container by the amount of heat radiated from the surface of the container. It is about a heater.

In addition, the present invention, by heating the working fluid with the main heating source during the first heating operation, the temperature of the surface of the container is rapidly raised, and at the same time the metal mesh (screen) that also acts as a return means (week) of the working fluid The present invention relates to a heat pipe heater provided in the container.

In addition, the present invention is provided by supplying a power supply to the main heating source and the metal network when the surface temperature of the container reaches the target temperature by installing a pressure-responsive temperature control unit operating in accordance with the internal pressure of the container at one end of the container. The heat pipe type heater which was made to block this is related.

The present invention also relates to a heat pipe type heater in which a main heating source installed in an inner wall of the container, preferably in a spiral shape, performs a function such as a wick of a heat pipe.

The present invention also relates to an image fixing apparatus employing the heat pipe type heater as a heating roll of an image fixing apparatus used in a copying machine, a facsimile, a printer, or the like.

An apparatus for forming an image on a recording paper such as a copying machine, a printer, a facsimile, or the like, feeds the recording paper toward the drum on which the toner is coated, moves the toner onto the recording paper, and then the heating roll 900 shown in FIG. The toner is fixed on the recording paper by pushing the recording paper into the image fixing apparatus including the image fixing device 800.

In popular type copiers, heat transfer coils or halogen lamps are used in thin aluminum cylinders whose outer surfaces are coated with Teflon.

However, the heating roll 900 has the disadvantage that the temperature in the longitudinal direction and the radial direction of the cylindrical tube is not constant when the surface temperature of the aluminum cylindrical tube is raised by the heat generation of the heat transfer coil or halogen lamp 950. there was. In addition, since the central portion of the heating roll that comes into contact with the recording paper has more heat loss than both sides-that is, because the recording paper takes away the surface heat of the heating roll-it is almost impossible to maintain a constant temperature in all areas. It was. As such, when the surface temperature of the heating roll is different for each section, the printing state of the printed matter becomes poor.

This problem is exacerbated as the length of the recording paper is longer or the printing speed is faster, and the amount of heat per unit time transferred (lost) from the surface of the heating roll to the recording paper is compensated per unit time supplied from the heat transfer coil or the halogen lamp. This is because the effect is cumulative because it is larger than calories.

In order to improve this problem, a number of domestic and foreign patents have recently been proposed for the heating roll using the principle of the heat pipe.

As a domestic document on a heating roll using the principle of the above-mentioned heat pipe, there exist Unexamined-Japanese-Patent No. 2000-30160, 2000-12446, 2000-30111, etc., for example.

Each of the heating rolls described in the above documents, although there is a slight difference in the detailed configuration, is commonly filled with a predetermined working fluid in a negative pressure (vacuum pressure) state in a double tube type container in which both ends are closed, and both ends are opened. Halogen lamp is inserted into the hollow part of the double tube type container.

By the way, the heat pipe type heating roll, the inner shell of the container is heated by the halogen lamp, and the heated endothelial heats the working fluid, and the working fluid whose phase is changed into a gas state by the heating action is the outer shell of the container. Heat is transferred back to the surface temperature so that the surface temperature is raised to a desired target temperature, and it takes a long time to raise the surface temperature of the container to the target temperature, and from the heat generating means (halogen lamp) through three heat transfer processes Since heat is transferred to the outer surface of the container, there is a disadvantage that the thermal efficiency is lowered.

In addition, in addition to the above-described disadvantages of the function, there is a disadvantage that the size of the heating roll is increased by forming a hollow portion for fitting the halogen lamp in the shaft portion of the container.

The present invention has been made to solve these problems, the first heating operation can be rapidly heated the surface temperature of the container by the main heating source or the metal mesh provided with the main heating source, the surface temperature of the container is the target temperature After reaching, the auxiliary heating source compensates for only the amount of heat lost from the surface to maintain the surface temperature of the container at a constant level.In particular, the main heating source and the metal mesh return to the working fluid during steady state operation. An object of the present invention is to provide a heat pipe type heater (hereinafter referred to as a heater) which acts as a wick. Another object of the present invention is to provide an image fixing apparatus employing the heater as a heating roll for fixing toner.

In addition, an object of the present invention is to provide a heater and an image fixing apparatus using the same by manufacturing the container with a hollow metal tube, thereby reducing the weight and controlling the surface temperature of the container largely even with a small heat load.

In addition, an object of the present invention is to provide a heater or an image fixing device that makes the whole slim by embedding the working fluid and the main heating source in the filling space of the container.

In addition, the present invention is to set the heater or the image to connect the pressure-responsive temperature control unit with the power supply circuit so that the power supply to the main heating source and the metal mesh, and the auxiliary heating source can be controlled by the internal pressure of the container It is an object to provide a device.

1 is a cross-sectional view in the axial direction of the heat pipe heater of an embodiment according to the present invention.

Figure 2 is a cross-sectional view in the radial direction of the heat pipe heater of an embodiment according to the present invention.

3 is a schematic configuration diagram showing a conventional image fixing apparatus.

[Description of Drawing Reference]

100 ... container, 200 ... heating source,

300 ... metal mesh, 400 ... secondary heating source,

500 ... temperature control unit, 600 ... charging space,

700 ... wool, 800 ...

900 ... heating rolls.

Before describing the preferred embodiment of the present invention, the principle of the heat pipe applied in the heater and the image fixing apparatus (particularly, the heating roll) of the present invention will be described to help the understanding of the present invention.

As is well known, heat pipes are evaporated from one end of the container to the other end, i.e., relatively high temperature, through the process of saturating the working fluid charged into the container into a gas-liquid phase. A device for transferring heat (or heat) to a condenser having a low temperature at a part, and is a heat transport device that transfers heat by using latent heat of a working fluid. Such heat pipes exhibit very high heat transfer performance compared to conventional heat transfer equipment using a single phase working fluid.

The heat pipe described above is largely composed of a container, a working fluid, and a capillary structure.

The capillary structure is divided into screen wick, groove wick, and eye-drop type according to the shape, and is returned to the return path when the saturated liquid is returned from the condenser side of the relatively low temperature container toward the evaporator side. Plays the role of.

Precisely, the case where the return of the working fluid is performed by wick is called a "heat pipe", but since it can return the working fluid by gravity or centrifugal force, etc., it is collectively called "heat pipe."

Here, the return of the working fluid means the action of moving (pumping) the working fluid in a saturated liquid state toward the heat generating part (evaporation part). In general, the working fluid is preferably high density, surface tension, latent heat of evaporation and low viscosity of the liquid.

The operating temperature (set temperature, target temperature) of the heat pipe is determined according to the type and filling amount of the working fluid charged in the container, and the filling pressure, but in most cases, triple point and critical point The temperature is set between. This is described in detail in a number of documents.

In general, it is recommended to use a material that is not compatible with the working fluid as a material of the wick and the container, so that the container, etc. are not corroded or eroded by the chemical reaction with the working fluid.

Each of the above-mentioned matters is preferably considered sufficiently when configuring the heater and the image fixing apparatus of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In the present invention, an image fixing apparatus for fixing and fixing a toner on a recording paper with a heating roll, wherein the heating roll is a cylindrical container, a working fluid filled in the container under negative pressure, and a return path of the working fluid built into the container. A main heating source for heating the working fluid to rapidly increase the surface temperature of the container to a certain temperature through the phase change of the working fluid and the heat dissipation toward the recording paper in the container. An image fixing apparatus comprising an auxiliary heating source that compensates heat and maintains a surface temperature at a constant temperature is proposed.

Here, the negative pressure state is defined as a vacuum state or a low pressure state in which there is no oxygen or remains very sparse.

The optimum surface temperature required for the heating roll varies depending on the type of toner to be fixed on the recording paper. In most cases, the heating roll is heated until the surface temperature reaches 180 ° C. At this time, the heating of the heating roll is made by the heat of the main heating source. That is, heat is transferred from the main heating source to the working fluid in a thermodynamic saturation state, and the phase of the working fluid is changed by the heat.

The saturated gas portion of the working fluid contacts the inner surface of the container to provide a certain amount of heat to the wall of the container and condense itself into the saturated liquid. The amount of heat transferred to the wall surface of the container during the phase change process of the working fluid is equal to the amount of power or latent heat supplied to change a certain amount of the working fluid in the liquid state into the gas state. In this way, heat is transferred from the container to the toner on the recording paper, and the toner melts and is fixed to the recording paper by the amount of heat transferred. On the other hand, the surface temperature of the container is lowered by the amount of heat transferred from the surface of the container to the toner, but the surface temperature is kept constant regardless of the printing amount by continuously compensating for the amount of heat lost by the auxiliary heating source.

In addition, in the present invention, preferably by installing a metal mesh in the container, the metal mesh serves as a return path of the working fluid and at the same time serves as a secondary heating source for heating the working fluid together with the main heating source during the first heating operation. We propose an image fixing apparatus for performing the following.

In the first heating operation, power is applied to the metal network, and joule's heat is transferred from the metal network to the working fluid by the amount of power supplied. Therefore, the working fluid can be heated more rapidly, and the target temperature can be reached within a short time. In addition, when the saturated gas phase changes into a saturated liquid at the portion (condensation) where heat transfer is directed toward the recording paper, the metal mesh is fixed to the closest mesh (mesh) closest to the mesh. It performs the same function as the wick of the heat pipe which causes the adjacent main heating source to change phase again into a saturation gas. Preferably, the metal mesh is installed between the inner surface of the container and the main heating source, but in some cases, the metal mesh may be installed in a form surrounding the main heating source.

Further, in the present invention, more preferably, by providing a temperature control unit operating at one side end of the container in accordance with the internal pressure of the container, when the surface temperature of the container reaches the target temperature, the power supply to the main heating source and the metal mesh We propose an image fixing device which is made to be blocked. In the first heating operation, power is supplied to the main heating source and the metal network to start the heat generation. At this time, the working fluid filled in the container in a saturated state is heated. By heating, the phase of the working fluid changes and the internal pressure of the container rises. That is, the surface temperature and the internal pressure of the container are in proportional relationship. Therefore, when the surface temperature of the container rises, the internal pressure of the container also rises, and the temperature controller responding to the internal pressure operates to open the power supply circuit.

Further, in the present invention, for example, be buried beneath the road surface, such as emergency runway or trunk road in the area of heavy snowfall or freezing frequently, so that in the event of an emergency, a lot of heat can be radiated to the road surface at the same time to remove snow or ice for a short time A heat pipe type industrial heater comprising: a container; A working fluid filled in the container under a negative pressure; It is proposed that the main heating source is built in the container and serves as a return path of the working fluid and simultaneously heats the working fluid to rapidly raise the surface temperature of the container to a predetermined temperature through a phase change of the working fluid.

In addition, the present invention proposes a heater for which each characteristic configuration requirement applied to the heating roll of the image fixing apparatus mentioned above is selected.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of a heater and an image fixing apparatus using the same according to the present invention will be described. First, the term "condensation" in terms used in the description of each embodiment of the present invention means a region where the saturated gas phase changes to a saturated liquid because the temperature is relatively lower than the surroundings, and the evaporation portion is a saturated gas. It is defined as a changing area.

1 is a cross-sectional view in the axial direction of the heater of one embodiment according to the present invention, Figure 2 is a cross-sectional view in the radial direction of the heater of an embodiment according to the present invention.

In the drawings, a heater according to an embodiment of the present invention is configured to include a container, a main heating source, a metal net, an auxiliary heating source, a working fluid, and a temperature control unit.

Among them, the container which transfers heat through the outer surface toward the heating target (for example, recording paper or road surface), the main heating source to perform the heating operation when the power supply, and the main heating source (evaporation unit) A working fluid that transfers heat to the container (condensation unit) after the phase change from saturated liquid to saturated gas by heat, and condenses itself into saturated liquid, is an essential component.

In the present embodiment, the container 100 shown as a hollow cylindrical tube is preferably made of, for example, aluminum, but may be replaced with another metal as long as the metal is not compatible with the working fluid. In some cases, the outer surface of the container may be coated.

The thickness of the container is preferably as thin as possible within the range that can withstand the maximum expansion pressure of the working fluid to be filled in the container 100, because the thinner the thickness, the smaller the heat capacity of the container This is because even with a small heat load, the surface temperature of the heater can be rapidly lowered or raised, and the total weight of the heater can be reduced to provide convenience for transportation and handling.

As the main heating source 200 installed in the container, in this embodiment, an electrical resistance wire (heat wire; hereinafter referred to as a first heating wire) of a spiral type is used, and the first heating wire has a shape other than spiral, eg For example, it may be installed in a zigzag form.

In the present invention, in order to rapidly increase the surface temperature of the container at the initial start-up (at the time of the first temperature increase operation), a large power (P) is supplied to the first heating wire closely installed in a spiral form on the inner surface of the container. . At this time, the heat amount H (unit: cal) generated in the first heating wire is 0.24 x P x t (power supply time). On the other hand, in order to rapidly raise the surface temperature of the container, the resistance of the first heating wire is preferably as small as possible because the amount of heat H generated in the first resistance wire is inversely proportional to the resistance value. The amount of power supplied during the initial temperature increase operation is determined by considering, for example, the target temperature required for the heater and the latent heat of evaporation of the working fluid.

After the surface temperature of the container reaches the target temperature by the heating action of the first heating wire, the power supply is stopped and the function as the heating means is lost.

However, for example, when the heater of the present embodiment is applied to the image fixing device, it has a pumping force for returning the working fluid condensed in a saturated liquid state to the evaporation part by performing a relative rotational motion with respect to the working fluid. It will perform the same function as wick.

The illustrated metal mesh 300 has the same shape and function as the screen wick used in the heat pipe of the normal structure, but is characterized in that it becomes a direct electric resistor during the first heating operation and generates heat together with the first heating wire. Configuration requirements. According to the metal mesh described above, the surface temperature can be raised more rapidly than when the surface temperature of the container is raised only by the main heating source (first heating wire).

As the auxiliary heating source 400 provided outside the container, in this embodiment, an electrical resistance wire (hereinafter referred to as a second heating wire) provided in close contact with the outer surface of at least one end of the container is used.

The second heating wire bears part of the load of the first heating wire during the first heating operation, and also prevents a temperature drop along the axial direction of the container. When the heater of the present embodiment operates in the normal state, it generates heat to heat the outer surface of the container.

The illustrated temperature control unit 500 is represented by bellows filled with an inert gas therein in this embodiment. This bellows is installed at one end of the container and responds to the internal pressure of the container to repeat contraction and expansion.

That is, when the surface temperature of the container is low (low temperature state), since most of the working fluid is in a saturated liquid state, the internal pressure is lowered, and thus the bellows filled with the inert gas at a constant pressure is expanded. On the contrary, when the surface temperature of the container is high, the bellows contracts. Therefore, if the power supply circuit switch of the first heating wire, the metal mesh, or the second heating wire is connected to the volume change of the bellows, the surface temperature of the container can be controlled. Therefore, the operating temperature (target temperature) value required for the heater of this embodiment can be easily set by adjusting the internal charging force of the bellows using the pressure regulator 550.

Here, although the auxiliary heating source, the metal mesh, and the temperature control unit are not necessary among the above-described configuration requirements, it is preferable to adopt all of these configuration requirements when configuring the heater or image fixing apparatus of the present embodiment. Further, too obvious technical matters, for example, the general matters such as the both ends of the container is sealed with an end cap, a closing plate or the like, but not disclosed, these are of course reflected in each embodiment of the present invention. In addition, when the technical idea of the present invention is applied to the image fixing apparatus, it is not to be overlooked that what is necessary in the above-mentioned conventional document configuration requirements may be adopted.

Hereinafter, the operation and function in the case where the heater according to an embodiment of the present invention is employed as a heating roll of the image fixing apparatus will be described.

First, when the switch is turned on to operate an apparatus for forming an image on a recording paper such as a copying machine or the like, power is supplied to the first heating wire acting as the main heating source 200 in this embodiment and starts to generate heat. At the same time, the heating roll starts to rotate.

At this time, when the heating roll employs a metal mesh as a secondary heating source, power is also supplied to the metal mesh 300 to generate heat. Therefore, it is possible to raise the surface temperature to the target temperature at a higher speed than that of raising the surface temperature of the container with only the main heating source, that is, in a short time.

In this way, the heat generated from the main heating source and the metal mesh 300 is transferred to the working fluid in the adjacent saturated liquid state and the wall surface of the container. The heat transferred to the pool 700 of the working fluid accumulated in the inner space of the container, that is, the bottom of the filling space 600, is used as a latent heat required to change the working fluid in a saturated liquid state into a saturated gas or phase change. Is absorbed. On the contrary, the working fluid fixed in the form of a thin film between the mesh of the metal mesh by the surface tension or the surface of the first heating wire acting as a main heating source or between the first heating wire and the inner surface of the container is transferred. The phase changes from saturated liquid state to saturated gas state by heat. In this way, the working fluid having a phase change in the state of saturated gas is in contact with the wall surface of the container transfers the heat stored in the form of latent heat toward the wall surface and condenses itself into the saturated liquid. The working fluid condensed with the saturated liquid flows back to the pool 700 or is fixed in the form of a thin film on a mesh of a metal mesh, and is heated again to change phase into a saturated gas.

If this phase change process of the working fluid occurs continuously, the surface temperature of the container rises to, for example, 180 ° C.

On the other hand, when the surface temperature of the container reaches the target temperature, the power supply to the main heating source or the metal net is stopped so that the temperature does not increase any more.

The power supply to the main heating source or the metal network may be stopped by a conventional temperature detecting means, but may also be achieved by a bellows type pressure actuating temperature controller 500 provided in the present embodiment. Rather, it is preferable to adopt the pressure-responsive temperature control unit 500 in the following points.

That is, in the related art, in order to detect the surface temperature of the heating roll, a temperature detecting means is provided at one end of the outer surface. As mentioned above, the surface temperature of the center portion in contact with the recording paper is lower than the surface temperature of both sides. Therefore, the temperature distribution in the axial direction was inevitably uneven. Therefore, when the surface temperature of both sides of the container is detected and power supply and interruption are determined, it is difficult to optimally maintain the surface temperature of the central portion, which is the working area, and the quality of the printed matter is sometimes poor.

On the other hand, since the temperature control part 500 of this embodiment responds to the internal pressure of the container which is a rigid state quantity, it can measure the supply and interruption time of a power supply precisely. Therefore, the surface temperature of the center portion, which is the working area, can be optimally maintained, so that the quality of the printed matter is good.

On the other hand, if the power supply is still, the surface temperature decreases due to heat radiation from the surface of the container (or heating roll) to the surrounding air, and the surface temperature decreases significantly during image fixing such as copying or printing. Get up quickly. This is because, during the image fixing operation, heat transfer occurs from the surface of the container to the recording paper or toner, which causes a large amount of heat to be lost instantaneously.

With respect to the surface temperature drop of such a container, conventionally, halogen lamps generate heat and compensate for the three steps of heat transfer. However, in the present invention, by directly heating the surface of the container with the second heating wire, it is possible to sufficiently compensate the temperature even with a small power to prevent the waste of power. This effect, which was not seen in previous heat pipes or image fixing devices, reflects the fact that the smaller the intermediate heat transfer step, the higher the heat transfer amount when transferring heat from the hot end to the cold end.

The heater or image fixing device of the present invention configured as described above has the following unique effects.

First, according to the present invention, since the heat generated during the heat generation process at the first temperature rise is directly transmitted to the wall of the container or directly to the working fluid, the surface temperature of the container is increased by at least one step shorter than the conventional heat transfer process. There is an advantage that the temperature can be rapidly raised to the target temperature in time.

Secondly, after the surface temperature of the container reaches the target temperature, the auxiliary heating source directly compensates only the amount of heat lost from the surface, thereby maintaining the surface temperature of the container at a constant level even with a small amount of power.

Third, in the present invention, the main heating source or the metal mesh acts as a heating means (heating source) when the temperature is initially raised, and then the surface temperature of the container reaches the target temperature, and after the power supply is stopped, the working fluid condensed while rotating with the container. By performing the function of the wick pumping the evaporation portion has the advantage of shortening the return path of the saturated liquid than the conventional heat pipe.

Fourthly, in the present invention, the surface temperature of the container can be precisely controlled by linking the power supply to the main heating source, the metal mesh, and the auxiliary heating source with the temperature control unit that responds to the internal pressure of the container. There is an advantage.

Fifth, the present invention preferably has a merit that the surface temperature of the container can be largely adjusted with a small heat load while reducing the weight by making the container with a hollow metal tube.

Sixth, the present invention has the advantage that the whole can be made slim by embedding the working fluid and the main heating source in the container filling space.

In addition, by filling the working fluid in a negative pressure state, there is an advantage of preventing the oxidation of the first heating wire acting as the main heating source and extending the life.

Claims (7)

An image fixing apparatus for fixing a toner on a recording sheet by melting with a heating roll, The heating roll A cylindrical container; A working fluid filled in the container under a negative pressure; A main heating source embedded in the container to serve as a return path of the working fluid and to heat the working fluid to rapidly raise the surface temperature of the container to a predetermined temperature through a phase change of the working fluid; And an auxiliary heating source configured to compensate for the amount of heat radiated from the container to maintain the surface temperature at a constant temperature. The method of claim 1, And a metal mesh is installed in the container to serve as a return path of the working fluid and at the same time serve as a secondary heating source for heating the working fluid together with the main heating source during the first heating operation. The method according to claim 1 or 2, And a temperature controller is installed at one end of the container to detect a change in the internal pressure of the container according to the phase change of the working fluid to close the supply of power to the main heating source. delete With a container; A working fluid filled in the container under a negative pressure; The main heating source is built in the container and serves as a return path of the working fluid and simultaneously heats the working fluid to rapidly raise the surface temperature of the container to a predetermined temperature through a phase change of the working fluid. A heat pipe type heater, characterized in that an auxiliary heating source is provided on the outside of the container to compensate for the amount of heat radiated from the surface to maintain the surface temperature at a constant temperature. The method of claim 5, Heat pipe type heater, characterized in that the metal mesh is installed in the container to serve as a return source of the working fluid and at the same time as a secondary heating source for heating the working fluid with the main heating source during the first heating operation. . The method of claim 6, And a temperature control part is installed at one end of the container to detect a change in the internal pressure of the container according to the change of the working fluid to open the power supply to the main heating source.