EP1366228B1 - Pulsed steam iron - Google Patents

Abstract

The invention relates to an iron (1) comprising a container of water (2) at atmospheric pressure. The water from the container flows through a nozzle between said container (2) and a heated and regulated steam chamber (5). An iron sole plate (3) forms the ironing surface and steam outlet holes (12) are arranged in said sole plate (3). The invention is characterized in that the iron (1) comprises means for creating a resonance or relaxation vibration in the water and steam circuit. The cyclic variation in the steam pressure is automatically maintained at an average pressure above that corresponding to the column of water available in the iron.

Description

The present invention relates to steam irons where the vaporization of water is almost instantaneous.

Steam irons generally comprising a water reservoir, a heated spray chamber to quickly evaporate the water that reaches it drip tank, a heated soleplate with the surface of ironing, steam outlet holes being formed in the soleplate.

The simplest irons have an adjustable flow valve through which the water drop of the tank in the vaporization chamber under the effect of gravity. The produced vapor comes out of the iron to the atmosphere through channels and holes of output constituting a steam exhaust circuit. But the steam occupies a large volume and runs through the exhaust system at high speed. As a result pressure drops of this circuit, the pressure of the steam in the chamber of vaporization increases. Moreover, when the iron is applied on the fabric ironed, the steam outlet through the holes of the sole is thwarted and the pressure in the vaporization chamber increases further.

This internal pressure in the vaporization chamber is opposed to the passage of water in the adjustable flow valve, which significantly decreases the amount following steam produced. The internal overpressure can not exceed one value corresponding to the height of the water column between the exit of water from the valve and the level of water in the tank, usually a few centimeters. As a result, the amount of steam varies greatly during ironing, according to the fabrics and the ironing support. Load losses being proportional to the square of the velocity of the vapor in the circuit, the speed is limited, in particular the speed of exit through the holes of the sole, which can be a disadvantage for the penetration of steam into the fabrics. Moreover, steam can not be used in a sprayer, which requires too much pressure for its operation.

These disadvantages justify the use, in more elaborate irons, of a pump which forces the passage of water from the reservoir to the chamber of vaporization, the pressure delivered by the pump being much higher than that which is generated by the losses. But this solution increases the price of iron for the value of a pump, its setting up and its device power supply if it is electric.

There are also known devices using the variations of the vapor pressure in the vaporization chamber between the periods when the iron is placed on the fabric and those where it is not, this to force the passage of water. Such a device is described for example in the patent FR2626901. But these devices are also expensive and delicate.

Patent JP01262899 discloses an iron comprising a steam valve whose control rod is driven by an electromagnet. The valve is actuated periodically to produce an excess of steam so as to clean the steam room. Overpressure occurs when closing the valve. But this device is not intended to continuously obtain a powerful steam.

The steam can also be pressurized high, which solves these problems. This is the case when iron includes - or is associated with - a steam generator having a closed boiler in which a body of water tip slowly. But these systems are expensive.

The object of the invention hereinafter is to overcome these drawbacks by proposing a economic iron in which the average pressure of the steam generated is sufficiently high to overcome overpressures due to ironing and / or to allow high vapor output rates and / or to allow the use of steam in a sprayer.

The object of the invention is achieved by an iron comprising a reservoir of water at atmospheric pressure, the water of the reservoir flowing through a nozzle between this reservoir and a heated and regulated vaporization chamber, a soleplate having the ironing surface, steam outlet holes being formed in the soleplate, remarkable in that the iron comprises resonant means or relaxation vibration the water circuit and steam, the cyclic variation of the vapor pressure being self-maintained at an average pressure greater than that corresponding to the water column available in the iron.

Figure 1 in the appendix shows how we surprisingly obtain such iron. This figure is a graph of the mass flow rate Q of steam in grams per minute depending on the total section S in square millimeters of steam outlet ports, for different nozzle passage diameters of a prototype. The diameters are marked on each curve.

The prototype originally equipped with a nozzle with a diameter of 0.95mm had an initial steam outlet section of 80mm2. Exit holes from steam were gradually removed to decrease the output section. In this operation, up to a section of 25mm2 approximately, we saw the flow of Steam slowly decrease without surprise. Then continuing the decrease, the iron surprisingly produced more and more steam, up to 24 grams per minute with a steam outlet section of only about 10 mm2, and with a high output speed. At the same time, it can be seen that iron emits a noise and that the average pressure in the vaporization chamber increases dramatically to greatly exceed the value corresponding to the height of the water column feeding the nozzle. We notes with satisfaction that the steam then has a high speed and a good effect of penetration into ironed fabrics, without the application of iron on the fabric substantially reduces the flow of steam. We can see that the pressure varies periodically. There are also steam discharges at through the nozzle. The steam is immediately re-condensed in the water tank causing small implosions at a fast pace.

The phenomenon is not clearly explained. Partly, we can think that the steam chamber behaves with the exit holes as a cavity resonant Helmholtz that would be excited by the vaporization of water. Partly we can think that the implosions of the steam in the tank just above of the valve propel the water forcefully into the chamber as would a pump. As the vaporization chamber is a cavity that is not drawn to have a low resonant frequency from the acoustic point of view, one can think that phenomena combine and that when enough energy can be maintained in the resonator thus formed, it oscillates by generating significant overpressures which cause a high average pressure.

This is achieved when the steam outlet passage is properly adjusted with the passage in the nozzle. Compared to the known irons it is necessary to diminish substantially the steam outlet and increase the passage in the nozzle, which, without the previously described effect, could have raised fears that the overpressure of Steam due to the abundance of water prevents operation.

Overpressure is obtained for a value of the steam outlet section less than a critical value. For close upper exit sections of this critical value, the start of the described operating mode is obtained by shaking or abrupt opening of the nozzle. Operation can then present an instability, which can be explained by a loss excessive energy through the exit holes, or by great difficulty in transform the pressure energy into sufficient kinetic energy. This energy is normally responsible for creating a temporary depression in the chamber and suck the water through the nozzle.

FIG. 1 shows various curves of a prototype relating to nozzles whose passage diameter is different. The zone or operating mode sought is stable and starts spontaneously and is limited to the right by a curve A in dashed line. This curve represents the solutions of a function f (S, Q) = 0 which can be interpolated by a polynomial in the useful zone. As an example in the particular case of the prototype of Figure 1 this function is written: E (S, Q) = 0.00027Q 3 -0.035Q 2 + 1.258Q-S + 8.18.

With S expressed in square millimeters and Q in grams of steam produced by minute. The function F (S, Q) is zero for the points chosen on the line curve dashed, positive if one chooses a point M (S1, Q1) of stable operation and negative if the operation is unstable.

Preferably the passages in the steam outlet holes and the diameter of the nozzle are adjusted so that the function F (S, Q) = m10 -4 Q 3 -n10 -2 Q 2 + pQ-S + q positive, where Q is the mass flow rate of steam (in g / min)
S is the total section of the orifices (in mm2).

With regard to the prototype described, with a type of arrangement and determined sole,
m is from 1.5 to 3.5, preferably 2.5
n is between 2 and 4.5, preferably 3.5
p is between 1 and 2, preferably 1.25
q is from 7 to 10, preferably 8.

However the parameters vary with iron construction and other beaches value must be calculated to accurately represent the behavior other constructions.

We thus adjust the passages in the holes to be in the zone where the function F (S, Q) described is positive, ie located to the left of the dashed line in the particular case of Figure 1. We can not only adjust the section passages but also their length in order to adjust the effects of inertia of the steam circulating in these high speed passages.

Preferably the nozzle is constituted by the passage of an adjustable flow valve.

The steam outlet section is chosen to suit a wide range of valve openings, so as to maintain a flow control easily possible in the described operating mode.

In a second version, the iron comprises a non-return valve between the tank and the spray chamber.

Too high a temperature of the tank water impairs the proper functioning oscillations. The non-return valve has the advantage of preventing the return of steam in the water tank, and thus its slow warming.

The valve and the adjustable valve can advantageously be combined to to make a subassembly. In this version the operation has first seemed much more critical with spray chambers and circuits known steam. Indeed the check valve removes small implosions described above.

Usefully, the steam circuit has elongated passages where the steam circulates at high speed which make up with the flapper and the chamber of vaporization a stable oscillating steam circuit.

We thus find the operating stability, even at steam flow rates modest. Steam is forced, before escaping, to travel at great speed one or relatively long passages and low section relative known steam circuits. As a result, a large mass of steam is put in the passages during vaporization and acquires energy kinetics thus transforming the pressure energy generated in the chamber of vaporization. When the vaporization of the water introduced into the chamber is ends, this kinetic energy helps to empty the chamber of its vapor remaining for a sufficient period of time, causing the flap to open, a new water intake, a new vaporization, and the cycle start again. The operating frequency is not equal to the frequency of acoustic resonance of the steam circuit because the high pressure lasts as long as the water admitted suddenly is not all evaporated. Also it is enough that the circuit has enough energy to open the valve at the end of evaporation so that the system works.

We find a characteristic operation similar to that described in Figure 1 if the section S is replaced on the abscissa by a product comprising the section and the inverse of the length of the output circuit. The set can therefore be adjusted to obtain spontaneous and stable oscillations.

In an alternative embodiment using a valve, there is a stable oscillatory operation by substantially increasing the dimensions orifice, to compensate for the lack of small implosions, and using a very light valve, in series with the drip, without modifying the classic general design of the sole steam circuit. In this pulsating regime, the flow obtained is important, advantageous for ironing difficult parts.

Usefully, the drip followed by a valve includes a module closing a large passage intended to allow a large flow of water to pass more quickly and pierced with the proper orifice of the drip. The orifice is released gradually by a needle stem in a first part of his control stroke and the largest flows of water and steam are obtained in a second part of the rod run where the module is gradually raised.

In the absence of other modifications, the presence of the flapper increases the curvature to the left and bottom of a curve A similar to that visible in FIG. 1, and decreases the orifice and outlet section flow rate equal to so that low Q operation does not allow self priming oscillations. The presence of the valve therefore requires greater equal-flow openings as the first version described. It also moves the upper part of the stability curve A on the right of the diagram. Stability is improved for large orifice openings and high flows, which is can explain by the absence of return and therefore of energy losses in the tank. The steam outlet section S may be larger.

When the needle gradually clears the orifice, a flow of steam Q relatively small, but sufficient for ironing parts that are easy to ironing is obtained. Steam produced in small quantities is incapable of raise the pressure, close the flap and swing the iron. When the opening of the orifice is increased, for a section S0 of constant output, the operating point is moving into the area where the steam is produced spontaneously the previously described oscillations. Water admitted quickly in the room produces a whiff of steam partially retained by the calibrated outlet, the pressure rises by closing the valve and the admission of water, the vaporization continues at high pressure until exhaustion the amount of water admitted and evacuation of the steam, after which the flapper opens and the cycle starts again. This oscillatory regime ensures a flow and a Vapor pressure is important and effective for ironing difficult items. The user of iron therefore has two modes of operation of the iron appropriate to the different difficulties of ironing.

In a third version of the invention, the iron comprises a flap fixed passage acting as a nozzle between the reservoir and the chamber of vaporization.

This version works like the previous one, but the steam flow is limited by the steam outlet circuit.

Preferably the iron further comprises a flow control valve of steam located on the steam circuit.

Steam flow is limited by acting on the steam circuit rather than on the water circuit as in the second version. Moreover, the operation oscillations is the same as in this second version.

La figure 1 est, comme on a déjà pu le voir, un diagramme des courbes caractéristiques du débit massique de vapeur d'un fer selon l'invention en fonction de la sortie de vapeur.

La figure 2 est un diagramme des courbes caractéristiques du débit massique de vapeur d'un fer selon l'invention en fonction de la sortie de vapeur au voisinage du fonctionnement à sortie de vapeur S0 constante.

La figure 3 est le diagramme de la courbe caractéristique du débit massique de vapeur d'un fer selon l'invention ayant un passage d'admission d'eau maximal et constant ainsi qu'une section de sortie de vapeur variable.

La figure 4 est une vue en coupe longitudinale d'un fer selon une première version de l'invention.

La figure 5 est une section montrant le goutte à goutte et le clapet d'un fer selon une deuxième version de l'invention.

La figure 6 est une vue en coupe longitudinale d'un fer selon une deuxième version de l'invention.

La figure 7 est une vue de détail en coupe longitudinale d'un fer selon une troisième version de l'invention.

La figure 8 est une vue en coupe longitudinale d'un fer selon une troisième version de l'invention.

La figure 9 est un diagramme des courbes caractéristiques d'une variante d'un fer selon l'invention représentant le débit massique de vapeur en fonction de la sortie de vapeur.

La figure 10 est une section montrant le goutte à goutte et le clapet d'une variante de l'invention.

The invention will be better understood on reading the examples below and the accompanying drawings.

FIG. 1 is, as we have already seen, a diagram of the characteristic curves of the mass flow rate of an iron according to the invention as a function of the steam outlet.

FIG. 2 is a diagram of the characteristic curves of the vapor mass flow rate of an iron according to the invention as a function of the steam outlet in the vicinity of the constant steam outlet operation S0.

FIG. 3 is the diagram of the characteristic curve of the vapor mass flow rate of an iron according to the invention having a maximum and constant water inlet passage and a variable steam outlet section.

Figure 4 is a longitudinal sectional view of an iron according to a first version of the invention.

Figure 5 is a section showing the drip and the valve of an iron according to a second version of the invention.

Figure 6 is a longitudinal sectional view of an iron according to a second version of the invention.

Figure 7 is a detail view in longitudinal section of an iron according to a third version of the invention.

Figure 8 is a longitudinal sectional view of an iron according to a third version of the invention.

FIG. 9 is a diagram of the characteristic curves of a variant of an iron according to the invention representing the mass flow rate of steam as a function of the steam outlet.

Figure 10 is a section showing the drip and valve of a variant of the invention.

In a first version of the invention shown in FIG. 4, the iron 1 has a water tank 2, a sole 3 in thermal connection with a body heating element 4 including a vaporization chamber 5 closed by a plate 6 and equipped with a heating element 7. The body 4 is regulated in temperature by a thermostat 22. A drip device 8 provides a passage of water from the tank 2 to the spray chamber 5. The drip has an orifice 9 whose section can be reduced by a needle 10. The steam produced in the instantaneous vaporization chamber 5 is collected by passages or 11. It escapes into the atmosphere through one or more calibrated passages 12. Preferably the steam is then distributed under the sole 3 by a distribution chamber 13 from which it escapes through the holes 14 of the sole towards the fabric to iron.

Referring to FIG. 1 corresponding to the prototype, it can be seen that reducing the section S of the orifices 12 sufficiently, we obtain functioning which include a pulsating component and correspond to both at maximum steam flow and average internal pressure of steam. These diets have a spontaneous and stable functioning when the values are chosen to the left of the curve A dashed on the diagram.

We choose a maximum passage of the orifice 9 of the device drip 8 corresponding for example to the curve C0 of Figure 2 and we choose to calibrate the steam outlet 12 with a section S0, marked on the abscissa of Figure 2. The point M then represents the operation where the vaporization is maximum. The section S0 is chosen in relation to the curve C0 so that this point M is located in the stability zone. In a concrete embodiment, taken by way of non-limiting example of an iron having an installed power of 1900W, the section S0 is chosen equal to 13 mm ² and the drip has a maximum passage section of 1, 5 mm ² , the spontaneous oscillatory operation being obtained in this construction for values of S0 less than 24 mm 2.

When the needle is closed and the flow of water decreases, the point of operation m moves on the diagram of figure 2 when leaving vertically the curve C0 to get closer to the abscissa parallel to the ordinate axis. The S0 section is chosen so that in this operation moving the operating point cuts a maximum characteristic curves in the stability zone to allow adjustment without risk.

Under these conditions when the iron is hot and the user puts the vaporization in operation, the steam is produced spontaneously in a pulsating regime she does not perceive the vibrations. The steam generated at high pressure passes narrow outlet passages 12, whose pressure drop is much greater than the pressure losses that ironing can cause. Steam is emitted with strength and easily passes through the fabrics which makes ironing easier, or requires less steam at equal work. This helps maintain a healthy work environment.

In addition, it can be seen that pressure variations prevent scale from deposit on sensitive organs such as a bushel, and it becomes pulverulent for a large part. It evacuates easily with steam.

As a result, it has been possible, in a second version of the invention, to add a flap to the water inlet as shown in Figure 5. The valve is for example constituted by a ball 15 disposed in a bore at the end of the nozzle 9. Normally opened by the weight of the ball, the valve allows water to flow through tank 2 as the pressure in the chamber 5 is low, and then closes.

In one embodiment of this version shown in FIG. 6, the channels 11 are lengthened and calibrated with the same care as the outlets 12 so that that the high speeds of movement concern more steam. Finally evaporation of the water previously admitted into the chamber, the system then has more energy to create a depression in chamber 5 and open the flap. Channels 11 then have their input 16 remote from the output by 12. If necessary, the length of the channels 11 can still be increased for example by a tube 17 wound and having an entry into the chamber 5, as can be seen in Figure 7.

It is found that the operation has many similarities with the operation of the previous version, with the advantage that there is no back-up in the tank, which remains at normal room temperature.

In a preferred embodiment of the invention using a valve, the iron is an iron similar to that of Figure 4 but equipped with a wide-flow drip and a valve 15 visible in Figure 10. The output section of steam, marked S0 on an equivalent of FIG. 2, is reduced only so that the spontaneous initiation of the oscillations is obtained for an average opening of the orifice 9 of the drip. The valve 15 made of silicone elastomer in series with the drip, is advantageously very light. It has a large surface, facing the vaporization chamber, on which the vapor pressure can be applied to close easily. The drip may, optionally, include a module 25 carrying the orifice 9, said module being raised at the end of the opening stroke of the needle 10, to release faster a greater passage to the water tank. In a concrete embodiment, taken by way of non-limiting example of an iron having an installed power of 1900W, the section S0 is chosen equal to 40 mm ² and the drip has a maximum passage section of 1, 8 mm2 as long as the module is on its seat, and 25 mm ² when the module is fully raised. The oscillation operation is spontaneous for a section of the vapor passages S0 of up to 60 mm ² .

For easy ironing, the user sets the steam flow to a low level. In the diagram of Figure 9, the operating point lies between the points M0 and M1. The iron then works in a classical way, without oscillations pressure. When she wants to iron difficult fabrics, with a lot of very energetic steam, it increases the flow with the control of bushel. The iron then changes gears, the operating point m crosses the line stability limit and self priming A at M1, and is between the points M1 and M of the diagram of Figure 9. Maximum operating point m is in M on the curve C0 corresponding to the maximum opening of the orifice of the valve. The iron works with oscillations whose frequency is the order of 20 to 30 beats per minute for a prototype made. Steam coming out at high speed is very penetrating and effective. The prototype, as well equipped with a large water inlet and a valve, delivers 35 grams of steam per minute when the iron is raised, and another 32 grams per minute when it is applied on the ironing cloth. The flow of steam therefore varies very little with the ironing conditions.

A third version of the invention visible in FIG. 8, derived from the variant using a valve shown in Figure 6, uses a water passage of the tank 2 in the chamber 5 through a calibrated orifice 9 and provided with a valve having a ball 15. But the nozzle thus constituted comprises no organ water flow adjustment. The steam circuit is equipped with a flow control steam 20 consisting for example of a needle or a bushel acting at the junction of the channels 11 with the orifices 12.

The passage of the water in the orifice 9 being constant, only one of the characteristic curves similar to those previously described, for example the curve C0 of FIG. 3 corresponding to the maximum of the possibilities of vaporization. The adjustment device 20 being in full opening, it corresponds at the point Sm of the characteristic of the output and at the point M of operation. Channels 11 are calibrated so that this point of operation at full power is located in the stability zone.

When the adjusting device closes the exit, the point S'm approaches the origin of the abscissa and the operating point m follows the curve C0 with a corresponding steam flow, approaching the origins of the diagram. In the tests carried out, the curve A delimiting the stability zone is concave towards the origins, also this variant embodiment of the invention gives more accuracy and stability of oscillatory operation at low flow rates, at the price a slightly more complex arrangement. With this construction one can also add a valve 21 to close the passage of water to the chamber 5 when the user wants to iron dry.

Whatever the version, the steam comes out with enough force to can be used in a sprayer. All that is needed is to direct the exit of steam by a switch to a sprayer rather than to the chamber of steam distribution 13.

Many variants can be designed without departing from the invention. For example, a flow regulating device could be used. steam in the first version described. We can also easily adapt the invention to soles and steam chambers different from those which are illustrated, among others the adaptation can concern irons to several heating elements.

Claims (9)

1. An iron (1) comprising a water reservoir (2) at atmospheric pressure, the water from the reservoir flowing through an ajutage between the reservoir (2) and a steam chamber (5) that is heated and regulated, and a soleplate (3) including the ironing surface, steam outlet holes (12) being arranged in the soleplate (3), the iron (1) being characterized in that it further comprises means for putting the flow of water and steam contained in the water and steam circuit into resonance or relaxation vibration, the cyclical variation of the steam pressure being automatically sustained at an average pressure higher than the pressure that corresponds to the water column available in the iron.
2. An iron according to the preceding claim, characterized in that the steam outlet holes (12) and the diameter of the passage (9) of the valve (8) are adjusted in such a manner that an oscillatory regime is spontaneously obtained.
3. An iron according to claim 1 or claim 2, characterized in that the ajutage is constituted by the passage (9) through an adjustable flow rate valve (8).
4. An iron according to claim 2 or claim 3, characterized in that the iron (1) has a check valve (15, 9) placed between the reservoir (2) and the steam chamber (5).
5. An iron according to the preceding claim, characterized in that the steam circuit has long passages (11), where the steam can flow at high speed, said passages with the check valve (15, 9) and the steam chamber (5), constituting a spontaneously stable oscillating steam circuit.
6. An iron according to claim 4, characterized in that the iron has a regime of operation without oscillations and a regime of operation with oscillations.
7. An iron according to claim 1, characterized in that the iron includes a check valve of constant passage (9) acting as the ajutage between the reservoir (2) and the steam chamber (5).
8. An iron according to the preceding claim, characterized in that it also has a valve (20) situated in the steam circuit for regulating the steam flow rate.
9. An iron according to the preceding claim, characterized in that the steam circuit has long passages (11), where the steam flows at high speed, which with the check valve and the steam chamber (5) constitute a spontaneously stable oscillating steam circuit.

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