EP0195733B1 - Induction-heated industrial machine, in particular for laundry drying and ironing - Google Patents

Description

The present invention relates to an industrial machine with magnetic induction heating for drying and ironing linen, comprising a metallic heating cylinder, means for driving the heating cylinder in rotation, heating means incorporated in the heating cylinder, means for introducing the linen onto the heating cylinder, means for applying the linen to at least part of the periphery of the heating cylinder, means for setting in motion the means for applying the linen and means for detaching the linen with respect to the heating cylinder.

We already know of such laundry drying and ironing machines used in the field of laundry, in which the sheets loaded with water, after washing, are engaged on a rotating and heating steel cylinder and come out of the machine dry and ironed.

It has already been envisaged to apply to such machines several modes of heating the rotating cylinder.

According to a first heating mode, a double jacket cylinder is used which defines a space in which steam circulates under a pressure of a few bars. This heating mode involves the use of taps, pressure gauges, filters and traps and naturally requires a source of steam.

According to a second heating mode, a cylinder is used inside which is placed a gas burner, with automatic ignition and forced extraction of the burnt gases, associated with control and regulation means, such as a flame controller. electronic and safety solenoid valves and to various bodies, such as, in particular, taps, regulators, dust filters on the air mixer, set of interchangeable injectors to adapt to the quality of the gas. Such a heating method is complex and requires significant safety measures.

According to a third heating mode, of the electric type, resistors in the form of shielded heating pins made of stainless steel with double insulation on floating supports in steatite are incorporated into the cylinder in order to produce a heating by Joule effect. The heating pins can be twelve in number, supplied separately from a polyphase network in two groups of six, in order to ensure regulation by contactors with indirect relay control. With such a heating mode, the air between the pins which constitute the heating resistors and the heating cylinder is a very poor conductor of heat, so that the thermal inertia is very important at the switching on and off of the heater. This implies, in practice, using a double threshold temperature control.

According to a fourth heating mode, a sealed double jacket, containing a thermal fluid, is incorporated in the heating cylinder. This heating mode with indirect heat exchange ensures, by internal circulation of the fluid, a good distribution of the temperature without local overheating on the external surface of the cylinder. However, this heating mode is relatively difficult to implement, due to the required sealing conditions. The heating fluid consists of an oil which can be heated from a gas system, such as that mentioned above, placed in the center of the cylinder or using immersion heaters placed in the fluid bath and distributed in three groups connected in star or delta to the three phases of a three-phase supply network, the current in the immersion heaters being supplied via a rotary collector. It will be noted that the presence of electrical resistors, supplied directly at a voltage of 220 V or 380 V in an atmosphere highly charged with water vapor, tends to make safety problems vis-à-vis users critical.

Furthermore, with such a heating method, known as electric fluid, problems of electrical ignition occasionally remain. Such priming is harmful for various reasons and, in particular, at the security level, since the priming can occur in the heat transfer fluid itself, placed in a sealed sealed enclosure, as well as at the economic level, since the replacement of an immersion heater requires draining the heat transfer fluid and repairing the seal. In addition, for industrial machines located in cramped premises located in the basement, the disassembly of an immersion heater which requires significant clearance, of the order of 2.50 m for large machines, generally requires take the whole machine out of the room and repair it outside. The cost of replacing an immersion heater and the costs associated with immobilizing the machine when it is not operating are therefore very significant.

The various known heating modes are therefore either difficult to implement, or not very energy efficient, or are endowed with significant thermal inertia, or are liable to present shortcomings in terms of safety of use or reliability. .

The present invention aims, precisely, to remedy the aforementioned drawbacks and to produce a machine for drying and ironing the linen which comprises heating means of the electrical type which are easy to implement, capable of ensuring regular heating with a minimum of inertia. thermal and therefore, both energy efficient and increased safety vis-à-vis users.

The invention also aims to provide a machine whose reliability and service life are improved.

These aims are achieved by means of a machine of the type mentioned at the head of the description, in which, in accordance with the invention, the heating means incorporated in the heating cylinder are of the induction type and include a series of non-contiguous, parallel conductive bars. to the generators of the heating cylinder and regularly distributed inside the heating cylinder and defining a cylindrical zone of diameter less than the diameter of the heating cylinder, each conductive bar being disposed in a coating of electrically insulating material which is a good conductor of heat, the enro bage itself being surrounded by a magnetic metal casing in thermal contact with the internal face of the external metal wall of the heating cylinder and the various conductive bars being connected to each other and to an AC power source.

More particularly, the different busbars are divided into several groups of adjacent bars, each group of bars being connected to a different phase of a polyphase current supply source.

According to an advantageous characteristic, the conductive bars are made of solid copper and have a large cross section and the various groups of conductive bars are connected by a rotary collector to a secondary winding of a voltage transformer whose primary winding is connected to a AC power source through a reactive energy compensation capacitor.

In this case, the voltage across a secondary winding can be between around 30 and 50 Veff.

According to a particular characteristic, the metal casing, in thermal contact with the internal face of the wall of the heating cylinder, comprises a “U” profile whose free ends of the branches are turned towards said internal face of the wall of the heating cylinder.

According to a first embodiment, the sub-assemblies, constituted by a conductive bar, a coating and an external metal casing, are attached and fixed directly to the internal face of the external metal wall of the heating cylinder.

According to a second embodiment, the conductive bars surrounded by a coating are arranged in the longitudinal notches made on the periphery of a metal cylinder whose outside diameter is hardly less than that of the heating cylinder, which is placed so coaxial, inside the heating cylinder and which has, between its longitudinal notches, projecting parts whose external faces are welded to the internal face of the wall of the heating cylinder.

In general, the device according to the invention combines, in an original way, the modes of heating by conduction and by induction to allow industrial drying and ironing of the linen. The inductor used, which operates at the industrial frequency of the network, dissipates both heat by the Joule effect as a resistance and generates a magnetic field creating currents induced in the part to be heated. The mild steel metallic envelopes which constitute magnetic "breeches" channel the magnetic field, cause induction phenomena and also play the role of radiator vis-à-vis the Joule effect.

The device according to the invention operates under low voltage. The efficiency at the level of the inductor device itself is equal to unity due to the recovery of losses by means of thermal conduction. The reliability is very high, in particular because the conductors are massive copper bars, of large section. Energy efficiency is increased, compared to conventional devices, as are the safety conditions during use. Finally, the cost price of an installation according to the invention is not higher than that of a traditional installation.

• - la fig. 1 est une vue schématique en perspective d'une machine sécheuse-repasseuse à laquelle l'invention est applicable,
• - la fig. 2 est une vue schématique en coupe transversale de la machine de la fig. 1,
• -la fig. 3 est une vue schématique, en coupe transversale, montrant l'implantation d'un premier mode de réalisation de dispositif de chauffage à induction selon l'invention dans une machine des fig. 1 et 2,
• - la fig. 4 représente, schématiquement, en coupe transversale, un module élémentaire d'un second mode de réalisation de dispositif de chauffage à induction applicable à la machine des fig. 1 et 2 et,
• - la fig. 5 est une vue schématique d'un exemple de connexion électrique du dispositif de chauffage à induction selon l'invention.

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments, given with reference to the appended drawings in which:

• - fig. 1 is a schematic perspective view of a dryer-ironer machine to which the invention is applicable,
• - fig. 2 is a schematic cross-sectional view of the machine of FIG. 1,
• - fig. 3 is a schematic view, in cross section, showing the installation of a first embodiment of the induction heating device according to the invention in a machine of FIGS. 1 and 2,
• - fig. 4 schematically represents, in cross section, an elementary module of a second embodiment of an induction heating device applicable to the machine of FIGS. 1 and 2 and,
• - fig. 5 is a schematic view of an example of an electrical connection of the induction heating device according to the invention.

We see in fig. 1 and 2, a dryer-ironer machine 100, comprising a frame with a base 101 and side panels 102 and 103. An upper safety cover 104, a rear panel 105 and a lower front cover 106 provide user protection by isolating it from the essential organs of the machine constituted by a heating cylinder 150 and means 121 to 125 for applying the linen to the heating cylinder 1 50.

The wet linen to be dried and ironed, not shown in the drawing, is first placed in an upper introduction tray 1 1 to be, then, introduced on engagement straps 113 mounted on an engagement table 112 arranged between the upper introduction tray 111 and the heating cylinder 150. The engagement straps 113 are driven by a driving cylinder 114 housed in the engagement table 112 to bring the laundry into contact with the external face 151 of the heating cylinder 150 , at the top of it. A pressing cylinder 115, cooperating with the heating cylinder 150, contributes to spin the laundry brought into contact with the heating cylinder 1 50.

The heating cylinder 150 may have a diameter of the order of 500 mm and be made of steel with a wall of thickness approximately 8 mm. The length of the heating cylinder 150 can be between 1.50 m and 2.50 m depending on the intended uses. The nominal temperature of the heating cylinder is of the order of 160 to 170 ° C.

The laundry, introduced on the straps 113 of the engagement table 112 and inserted under the pressure cylinder 115, is then driven by the heating cylinder 150, itself driven in rotation by driving rollers 126, 127. The laundry is then kept pressed against the cylinder 150 by dryer straps 121, for example made of felt, which absorb the water contained in the linen by evaporation. The dryer straps 121 for applying the laundry to the cylinder extend over approximately three-quarters of the perimeter of the cylinder and are driven by a cylinder. drive 125. The dryer straps 121 have a return path located in the lower and rear parts of the machine and cooperate with an upper cylinder 122 located in the vicinity of the pressure cylinder 115, with a rear cylinder 123, with a lower tension cylinder 124 and with the drive cylinder 125 located at the front of the machine above a container 132 for receiving dry and ironed laundry. Blades 131 are arranged above the driving cylinder 125 to cause the detachment of the laundry relative to the heating cylinder 150 above the driving cylinder 125 and before the laundry, driven by the heating cylinder 150, reaches the point d introduction of the linen at the end of the engagement table 112.

The water vapor coming from the laundry is evacuated by an extractor system 141 placed at the rear, in the lower part of the machine.

We will now describe, with reference to FIGS. 3 to 5, a specific electrical heating device intended to be incorporated in the rotating cylinder 150.

The heating device according to the invention constitutes a three-phase inductor supplied from a current supply network at a frequency of 50 or 60 Hz and placed inside the rotating cylinder 150 a short distance from the internal face. 153 of the metal wall of the cylinder 150, but without the conductive elements 51 of the inductor being in electrical contact with the wall of the cylinder 150.

As can be seen in fig. 5, each of the three phases of the three-phase inductor consists of a set of conductive bars 51 parallel to each other and connected in series with each other. Fig. 5 represents a star assembly in which phase n ° 1 comprises three bars 1, 2, 3, phase n ° It comprises three bars 4, 5, 6 and phase n ° III also includes three bars 7, 8 , 9. The number of busbars connected in series for each phase could, of course, be different from three. In fig. 5, the various conductive bars 1 to 9, constituting the three-phase inductor, are shown unwound in the same plane to show an example of star mounting of the three phases. In reality, the conductive bars 1 to 9 are arranged so as to define a cylindrical surface 152 (FIG. 3) coaxial with the cylindrical wall of the drum 150 and disposed inside the drum 1 50. The conductive bars 51 can be in solid copper and are spaced from each other, as shown in fig. 3.

The three-phase inductor thus consists of three phases, each comprising several conductive bars placed in series electrically and through which the inductor current passes. The busbars of the three phases can, of course, also be connected in a triangle.

Each conductive bar 51 is integrated in an elementary module 50, such as that shown in section in FIG. 4. An elementary module 50 comprises an outer sheath 53 of mild steel, in the form of an inverted “U” profile, the branches of which have free ends in contact with the internal face 153 of the cylindrical wall of the cylinder 150. In each module elementary 50, a solid conductive bar 51, for example made of copper, is positioned in a sheath 52 made of electrically insulating material, while having good thermal conductivity and disposed inside the outer sheath 53. The sheath 52 of electrical isolation and positioning of a conductive bar 51 can be made, for example, of refractory cement. The external sheaths 53 are themselves welded by the free end of their branches to the internal face 153 of the rotating cylinder 150.

The various elementary modules 50, distributed inside the cylinder 150, can be produced in very different ways. Thus, there is shown in FIG. 3 an embodiment in which the outer “U” sheaths 53 of the various elementary modules are defined by the walls of notches 156 formed at the periphery of a metal cylinder 154 having a diameter barely less than the internal diameter of the heating cylinder 150. In this case, the projecting parts 157, located between the notches 156, are welded by their arcuate face 1 55 to the internal face 153 of the cylindrical wall of the drum 150, for example by electric spot welding along generatrices of the internal cylinder 1 54 (at the level of the projecting parts 157), in contact with the cylinder 150. The internal sheath 52 of each elementary module 50 and the conductive bar 51 can be arranged in the notches 156 of the cylinder 154, in the same way as in “U” shaped profiles 53, such as those shown in FIG. 4. The elementary modules 50 must be close enough to one another to ensure a good distribution of the heating at the periphery of the cylinder 150. At the limit, the various external “U” sheaths 53 adjacent can be in contact with each other. others, the conductive bars 51 remaining electrically isolated from each other by the inner sheaths 52.

We will now describe the operation of the induction device according to the invention.

The alternating inductive current, passing through the busbars 51, creates a magnetic field, both in the “U” profile 53 of mild steel and in the portion of the rotating cylinder 1 50 on which each profile 53 is welded. This field magnetic, reinforced and channeled by the "U" profiles 53, generates induced currents within these profiles 53 and the rotating cylinder 150. These, by Joule effect, heating, on the one hand, directly the rotating cylinder 150 , on the other hand, indirectly, by conduction towards the cylinder 1 50 of the heat dissipated in the profiles 53. The efficiency is notably increased by the presence of the refractory material 52 between each conductive bar 51 and the corresponding “U” profile 53 . In fact, the material chosen being relatively good conductor of heat, it transmits heat coming from the Joule effect losses due to the inherent resistance of an inductor bar 51 to the rotating cylinder 150.

Thus, all of the active power supplying the inductor is transformed into heating energy for the rotating cylinder 150, which gives the device excellent efficiency.

Just bring the modules close enough elementary 50 to obtain a good distribution of the heating.

The inductor thus defined has a certain impedance (resistance + reactance), which must be adapted vis-à-vis the supply network, as a function of the power to be injected into the heating cylinder 150. This is composed, essentially, the power required to heat the cylinder 150 from room temperature to about 160 ° C during the start-up phase of the machine and the power necessary for the evaporation of the water contained in the moving sheets on cylinder 150.

This impedance adaptation is carried out by a voltage transformer, the secondary of which delivers the inductor current which is conveyed to the inductor via a rotary collector.

Finally, the inductor being reactive and resistive, the cos ϕ of the installation is different from 1. We therefore advantageously have three reactive energy compensation capacitors on the primary side of the adaptation transformer, so as to bring back the cos ϕ to a value close to 1.

Note that the heating device according to the invention has little thermal inertia, which does not make it necessary to regulate with a double temperature threshold.

Furthermore, it can be noted that, for a standard machine 2.50 m in length, the power required is of the order of 25 to 30 kW, which is relatively low compared to the power required for other industrial machines. ironing machines known, in particular, electric heating machines with heating resistors which, for the same size of heating cylinder, would consume a power of the order of 50 kW.

In addition, the electrical voltage at the terminals of the inductor according to the invention remains in the low voltage field, with values of the order of 40 Veff, which very significantly increases the electrical safety with respect to users compared to known electric heating modes in which a supply voltage of 220 V or 380 V is directly applied to electrical resistances in an atmosphere highly charged with water vapor.

Claims (12)

1. Industrial machine heated by induction, comprising a metallic heating cylinder (150), induction- type heating means (50) incorporated to the inside of the heating cylinder (150) and means (126, 127) for driving the heating cylinder (150) in rotation, characterized in thatthe heating means (50) incorporated to the heating cylinder (150) comprise a series (1 to 9) of non-jointed conducting bars (51 parallel to the generatrices of the heating cylinder and regularly distributed inside the heating cylinder (150) while defining a cylindrical zone (152) of diameter smaller than the diameter of the heating cylinder, each conducting bar (51) being embedded in a material (52) which is electrically insulating and good conductor of heat, the embedding material (52) being itself covered with a metallic envelope (53) in thermal contact with the internal face (153) of the external metallic wall of the heating cylinder (150) and the different conducting bars (1 to 9) being interconnected and connected to an A.C. supply source.

2. Machine according to claim 1, characterized in that the different conducting bars (1 to 9) are distributed in small groups of adjacent bars (1 to 3, 4 to 6, 7 to 9), each group of bars being connected to a different phase of a polyphase current supply source.

3. Machine according to claim 2, characterized in that the different conducting bars (1 to 9) are distributed into three groups of three bars (1 to 3, 4 to 6, 7 to 9) connected to a three-phase supply source.

4. Machine according to any one of claims 1 to 3, characterized in that the embedding material (52) is a refractory cement.

5. Machine according to any one of claims 1 to 4, characterized in that the metallic envelope (53), in thermal contact with the internal face (153) of the wall of the heating cylinder, constitutes a U-section of which the free ends of the branches are turned toward said internal face (153) of the heating cylinder wall.

6. Machine according to any one of claims 1 to 5, characterized in that the sub-assemblies constituted by a conducting bar (51), an embedding material (52) and a metallic external envelope (53) are buitl-on and fixed directly on the inner face (153) of the external metallic wall of the heating cylinder.

7. Machine according to any one of claims 1 to 5, characterized in that the conducting bars (51), embedded in a material (52), are disposed in longitudinal notches (156) formed on the periphery of a metallic cylinder (154) of which the external diameter is hardly less than that of the heating cylinder (150), which is placed in co-axial manner inside the heating cylinder (150) and which is provided between its longitudinal notches (156) with projecting parts (157) of which the external faces (155) are welded to the internal face (153) of the wall of the heating cylinder (150).

8. Machine according to any one of claims 1 to 7, characterized in that the conducting bars (51) are produced in solid brass and have a large section.

9. Machine according to any one of claims 1 to 8, characterized in that the different groups of conducting bars (1 to 3, 4 to 6, 7 to 9) are connected by a rotary collector to a secondary coil of a voltage transformer of which the primary coil is cennected to an A.C. supply source via a reaching energy compensating capacitor.

10. Machine according to claim 9, characterized in that the voltage at the terminals of a secondary coil is comprised between about 30 and 50 Veff.

11. Machine according to claim 5, characterized in that the U-shaped metallic envelopes (53) are produced in soft steel.

12. Machine according to any one of claims 1 to 11, applied in particular for drying and ironing linen or similar articles, characterized in that it further comprises, means (111 to 115) for introducing the linen on the heating cylinder, means (121) for applying the linen on at least one part of the periphery of the heating cylinder, means (125) for moving the means (121) for applying linen and means (131,132) for detaching the linen from the heating cylinder.

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