EP0486640A1

EP0486640A1 - Gas-driven appliance for personal use, in particular hair curler

Info

Publication number: EP0486640A1
Application number: EP91910416A
Authority: EP
Inventors: Wilhelm Schneider
Original assignee: Braun GmbH
Current assignee: Braun GmbH
Priority date: 1990-06-11
Filing date: 1991-06-04
Publication date: 1992-05-27
Also published as: JPH05501149A; CA2064849A1; WO1991019943A1

Abstract

On propose un appareil à gaz à usage individuel, comportant une pompe à jet (10) et une veilleuse, avec lequel un combustible gazeux (58) est mélangé à l'air (60) au moyen de la pompe à jet (10) et avec lequel le mélange combustible/air (62) est brûlé, le combustible (58) traversant une fente d'étranglement (34) de largeur réglable, prévue dans la section amont d'une soupape (14), une buse d'entraînement (38) servant à former un jet libre étant disposée dans la section amont de la soupape (14), appareil comportant également un corps de buse réceptrice (44) disposé en aval de la buse d'entraînement (38) et avec lequel une paroi frontale amont (46) de ce corps de buse réceptrice (44) et une paroi frontale aval (40) de la soupape (14) forment une nouvelle fente d'étranglement (54) de largeur réglable traversée par l'air (60) entraîné par le jet libre. Cette disposition permet de faire varier le mélange combustible/air (62) selon le fonctionnement de l'appareil.There is provided a gas fired appliance for personal use, comprising a jet pump (10) and a pilot light, with which a gaseous fuel (58) is mixed with the air (60) by means of the jet pump (10) and with which the fuel/air mixture (62) is burned, the fuel (58) passing through a throttle slot (34) of adjustable width, provided in the upstream section of a valve (14), a driving nozzle ( 38) for forming a free jet being disposed in the upstream section of the valve (14), apparatus also comprising a receiving nozzle body (44) disposed downstream of the driving nozzle (38) and with which a front wall upstream (46) of this receiving nozzle body (44) and a downstream front wall (40) of the valve (14) form a new throttle slot (54) of adjustable width through which the air (60) driven by the free throw. This arrangement makes it possible to vary the fuel/air mixture (62) according to the operation of the appliance.

Description

Gas powered device for personal use, especially curling iron

The invention relates to a gas-powered device for personal use, such as curling irons, hair dryers, wax heaters or the like, with a jet pump and a small burner, in which a gaseous fuel, for example liquid gas or in particular isobutane, with the help of the jet pump with air mixed and the fuel / air mixture is conventionally burned with, for example, an open flame or catalytically, the fuel flows through a throttle gap of adjustable gap which is provided on the upstream section of a valve member, a driving nozzle for forming a free jet on the downstream section of the valve member and with a catch nozzle body located downstream of the driving nozzles.

Gas-operated devices are understood to mean, for example, curling irons, wax heaters, hair dryers, soldering irons, bottle warmers, lighters and the like, which mix a gaseous fuel, for example liquid gas and in particular isobutane, with air using a jet pump and conventionally or in particular also downstream of the mixing point burn catalytically. A gas-operated device of the type mentioned at the outset is already known from EP 0021 224 B1, the content of which is included in the disclosure content of the present application by express reference. In this known curling iron, a mixing tube designed as a venturi nozzle connects downstream of the driving nozzle. This catch nozzle body is funnel-shaped at its upstream end with an inlet opening which is considerably larger in relation to the diameter of the valve member. This measure is intended to improve the air entry into the mixing tube and the mixture formation. Low Axial displacements of the valve body with respect to the catching nozzle body play no role for the amount of air entrained by the free jet.

One problem is that a different mixture composition is required to ignite the mixture than when operating in the nominal load or part load range.

With standard size burners, there is enough space available to ensure appropriate mixture preparation by means of appropriate valves, flaps or similar devices. This is excluded in the field of fine and micromechanics, since there is neither the space for it, nor can parts of this size have a corresponding accuracy at acceptable prices and an acceptable service life.

It is currently being used to maintain the rich mixture required for ignition over the entire gas mass flow range, even if this entails an increase in fuel consumption and a reduced efficiency. A permanently lean setting is not possible since it is then no longer ensured that the mixture ignites, which would render the entire device unusable.

The invention is based on the problem of further developing a gas-operated device for personal use with a small burner of the type mentioned at the outset such that the mixing ratio (air volume flow / gas volume flow) can be largely adapted to the required theoretical or ideal profile. This problem is solved in the gas-powered device of the type mentioned in that an upstream end wall of the catching nozzle body and a downstream end wall of the valve member can be adjusted to a further throttle gap Form the gap width through which the air entrained by the free jet can flow.

As a result of this measure, in addition to controlling the gas volume flow by means of the valve member and also performing a control of the air volume flow by means of the valve member, the energy content of the fuel gas is better utilized, the operating time of the device with one tank filling is extended and more environmentally friendly combustion products are released to the outside.

In addition, the ignition safety of the device is not impaired by this measure, in particular a device equipped with a combustion catalytic converter can be started without problems by means of a short ignition explosion.

The upstream end wall of the trap nozzle body of the jet pump and the downstream end wall of the valve member, which in this case forms the propellant nozzle body and, as mentioned, is displaceable with respect to the trap nozzle body, are preferably designed and dimensioned such that at full ge ¬ opened valve, the cross-section between the two end faces becomes so small that despite the high throughput of the fuel through the driving nozzle, only a relatively small amount of air is entrained by the preferably annular throttle gap between the two end walls. This enables a rich, easily ignitable mixture to be reached, for example during the starting phase.

The normal operating point of the burner is reached when the throttle gap for the propellant gas is somewhat closed by the valve member and thus the propellant nozzle body in comparison to the ignition position, whereby there is only a relatively small reduction in the propellant gas flow, but due to the enlarged gap between the End faces of the propellant nozzle body and Catch nozzle body is entrained a significantly increased air flow. In this way, a considerably leaner mixture than previously possible is achieved in normal operation.

With a low propellant gas throughput, when the propellant gas throttle gap is closed further by the valve and the propellant nozzle body is thus further removed from the catch nozzle body, the amount of entrained air drops disproportionately due to the low throughput of propellant gas, as a result of which the mixture obtained becomes richer again. This effect can, if necessary, be eliminated or at least mitigated by measures known from WO 89/07898. The disclosure content of this publication WO 89/07898 is incorporated into this by explicit reference:

In one embodiment of the invention, the end walls are arranged and dimensioned with respect to one another such that the gap width of the throttle gap is limited at least in one end position of the valve member in such a way that, despite the high gas throughput through the propellant nozzle, a relatively small amount is obtained through the preferably ring shaped throttle gap and is entrained by driving jets. This promotes in particular the ignition behavior of the device in the starting phase, in which a rich mixture is desired.

An advantageous development of the invention consists in setting the ratio of the gap widths of the throttle gap in the two end positions of the valve body to be greater than two and in particular greater than four.

The formation of the throttle gap for the air flow is structurally particularly simple in that the end faces of the catching body and the valve member essentially completely overlap one another. lapping and are arranged in substantially parallel planes to each other.

The measure to increase the mixing ratio of the fuel / air mixture when using butane or isobutane between an ignition setting and a nominal load setting from approximately 25 to 35 also proves to be advantageous.

In an advantageous embodiment of the invention, the smallest width of the throttle gap is determined by a stop on at least one of the end walls. This ensures that the throttle gap for the air flow, in contrast to the throttle gap for the gas flow, cannot be closed completely, so that a minimal air flow is always entrained by the free jet during operation of the device.

In an advantageous development of the invention, at least three stops are provided in the form of strips which form an angle with respect to the radial extent of the end faces, so that the inflowing air receives a speed component in the circumferential direction. This measure makes it possible to improve the mixing ratio, in particular in the case of small gas mass flows, since the gas jet emerging from the propellant nozzle becomes turbulent even at low gas volume flows, which contributes to an increase in the delivery rate of the gas jet.

Rounding the outer edges of the end face and the inner edges in the transition area between the end face and the mixing tube reduces the risk of detachments, which can lead to unstable, periodically fluctuating flow conditions.

In a further embodiment of the invention, the widths of the two throttle gaps are caused by an axial displacement of the valve member. This can be changed in the opposite direction, so that a mixture course can be set in a structurally extremely uncomplicated manner as a function of the gas volume flow set in each case, which is largely approximated to the theoretical or ideal conditions.

The axial displacement of the valve member can preferably be carried out in a temperature-controlled or regulated manner by means of a temperature detection element which is assigned to the combustion chamber of the device. Furthermore, alternatively, a time-controlled or -controlled actuation of the valve member for varying the fuel / air mixture proves to be extremely advantageous, in particular if temperature control is dispensed with. The user of the device can, for example, operate or move the actuating means in a timed manner in the required manner after switching on the device.

Further features, advantages and possible uses of the invention result from the following description of exemplary embodiments, which is shown in more detail in the drawing. All of the described and / or illustrated features, alone or in any combination, form the subject matter of the invention, regardless of their summary in the claims or their relationship. Show it:

FIG. 1 shows a schematic diagram of the course of the gas mixture as a function of the gas mass flow, the ideal course, the course previously realized by known devices and the course generated according to the invention being compared;

FIG. 2 shows a section through the jet pump according to the invention, the position of the valve member at nominal power being shown in FIG. 2A and the position of the valve member at ignition power being shown in FIG. 2B. The ideal, real, and achievable mixture ratios according to the invention are shown schematically in FIG. 1 as a mixture ratio (air volume flow / gas volume flow) over the gas mass flow.

Curve 2 shows the desired ideal course: With increasing gas mass flow, the mixture becomes "richer", i.e. gas-rich. In order to be able to ignite safely, an appropriately rich mixture must be supplied in the start phase (2) of the device.

For this reason, curve 4 which has been achievable so far and which is favorable in the nominal load range (N) is shifted to small burners by supplying an excessive amount of gas according to curve 6.

According to the invention, a profile according to curve 8 is achieved which approaches curve 4 for small gas mass flows (S) and ideal curve 2 for large gas mass flows (Z).

This is made possible by the device shown in FIG. 2. A jet pump (10) designed according to the invention is shown in FIG. 2A in the position in the nominal load mode (N) and in the half designated with FIG. IB in the position ignition or starting mode (Z).

The gaseous fuel, hereinafter simply referred to as "gas" for the sake of simplicity, comes from a container (not shown) through a channel 18 in the direction of arrow 58 to the valve member 14 which is in a bore 16 with an adjoining chamber 24 is axially displaceably received in the housing part 12 along an axis 21. The exact actual design of the valve with valve seat, valve body and sealing surfaces is not shown in more detail for reasons of clarity. The valve body 14 has a blind hole 20 which is connected to the outer jacket of the valve body 14 and the chamber 24 surrounding the jacket via at least one further bore 22 running transversely to it. When the valve body 14 is open, the gas can flow through this chamber 24, which also receives a valve closing spring 28, and the bores 20 and 22 to the downstream end of the valve body 14. A sealing ring 26 between the valve body 14 and the bore 16 ensures sufficient sealing so that no gas can escape at this point. A throttle gap 34 for the gas volume flow is formed between the bottom 30 of the chamber 24 and the valve plate 32, the width of which can be varied by an axial displacement of the valve body 14.

An insert 36 is provided at the downstream end of the valve body 14, which closes the blind hole 20 except for the driving nozzle 38. It is of course possible to provide the blind hole 20 as a through hole and to insert the insert 36 at one end and the valve divider 32 at the other end.

The gas flows through the driving nozzle 38 into the catching nozzle body 44, which has an end wall 46 and a centrally arranged mixing tube 50, and, as is customary in jet pumps, entrains air from the area outside of this free jet.

The axial distance a between the wall 40 of the valve member 14 and the end wall 46 of the catching nozzle body 44 is now preferably small and their overlap in the radial direction is chosen to be large. End walls 40, 46 arranged and designed in this way are usually avoided or efforts are made to arrange them with the greatest possible distance in the axial direction and to achieve the smallest possible radial overlap. Otherwise, the end walls 40, 46 are arranged essentially in parallel planes to one another. As a result of this extremely advantageous measure, the throttle gap 54 between the end walls 40, 46 actually functions as a throttle for the air flow indicated by the arrows 60.

In order to avoid inadvertent closing of the throttle gap 54, in one embodiment of the invention it is provided to arrange stops 52 on one of the two end walls 40, 46 which define the smallest adjustable width a 'of the throttle gap 54. It is also possible to design these stop bodies 52 as strips which preferably enclose an angle other than zero with the radial direction, so that the inflowing air receives a velocity component in the circumferential direction. This measure makes it possible to improve the mixing ratio, in particular in the case of small gas mass flows, since the gas jet emerging from the driving nozzle becomes turbulent more quickly, which increases the delivery rate.

The radially outer edges 42 of the end wall 40 of the valve member 14 and the radially inner edges 48 of the end wall 46 of the collecting nozzle body 44 are preferably rounded off in order to reduce the risk of detachments. Such detachments can lead to unstable, periodically fluctuating flow conditions, through which the composition of the gas / air mixture also changes periodically, which can even lead to the termination of the combustion process.

Since the most favorable dimensions and parameters of the invention have to be determined from case to case, only typical values can be given here:

The calorific power of burners in which the invention is typically applicable is 50 to 100 watts, butane or isobutane is to be mentioned as the fuel. The gas mass flow is 1-2 mg / s; the mixing ratio air / gas (vol./vol.) is about 35 at 1 mg / s and about 25 at 2 mg / s.

The diameter d of the mixing tube 50 through which the fuel / air mixture 62 flows is approximately 1.5 mm, the valve stroke h approximately 0.4 mm and the distance a fluctuates between 0.1 and 0.5 mm depending on the current status of the valve. The radii of the rounded edges 42, 48 are 0.6 mm.

If other fuels are used, the ideal mixing ratio must be changed according to the stoichiometric ratio; a larger mixing ratio requires a larger mixing tube diameter d and a correspondingly larger distance a.

Preferred parameters are:

h: valve stroke d: hydraulic diameter of the bore 11 a: face distance r: radius of the rounds 5, 6

h / d = 0 to 1.0 a / d = 0.1 to 1.0 r = 0.3 d to 1.0 d

The control is carried out as before by adjusting the valve. This can be positively guided via actuating means 56 such as bolt linkages, screws, etc. or it is pressure-controlled under the action of the pressure of the gas 58, a higher pressure of the gas 58 causing the nozzle body to be lifted from the valve seat to a greater extent. The control mechanism with which the Desired power can be set, act on the end of the spring 28, which rests in the illustrated embodiment in the chamber 24 on the housing part 12. The actuating means 56 can be acted upon particularly advantageously by a time-controlled or temperature-controlled control or regulation, so that the mixture can be set as a function of the operating state of the device.

It is of course possible to provide additional safeguards in both types, for example against overheating, in the form of a body which expands in the heat and thereby presses the valve body 14 into the closed position.

The invention is not limited to the exemplary embodiment shown, but can be varied in various ways. It is essential that, when the stroke of the valve body 14 is varied and the width h of the throttle gap 34 is changed, the width a of the throttle gap 54 takes into account a noticeable change in the radial overlap of the two end walls 40, 46 amount of air conveyed.

Claims

1. Gas-operated device for personal use, such as curling irons, hair dryers, wax heaters or the like, with a jet pump (10) and a small burner, with a gaseous fuel (58), for example liquid gas or in particular isobutane , mixed with air (60) using the jet pump (10) and the fuel / air mixture (62) is conventionally burned with, for example, an open flame or catalytically, the fuel (58) having a throttle gap (34) flows through an adjustable gap width, which is provided on the upstream section of a valve member (14), a drive nozzle (38) for forming a free jet is arranged on the downstream section of the valve member (14) and with one downstream of the drive nozzles (38) Genen catch nozzle body (44), characterized in that an upstream end wall (46) of the catch nozzle body (44) and a downstream end wall (40) of the valve member (14) NEN form a further throttle gap (54) adjustable gap width, through which the air (60) entrained by the free jet can flow.

2. Gas-operated device according to claim 1, characterized in that the end walls (40, 46) are arranged and dimensioned such that at least in an end position of the Ventil¬ member (14) the gap width of the throttle gap (54) is limited so far that Despite the high gas throughput (58) through the driving nozzle (38), only a relatively small amount of air (60) passes through the preferably annular throttle gap (54) and is torn by the driving jet.

Gas-operated device according to claim 1, characterized in that the ratio of the gap width of the throttle gap (54) in the two end positions of the valve body (14) is greater than two and in particular greater than four.

Gas-operated device according to claim 1, characterized in that the end walls (46, 40) of the catch body (44) of the valve member (14) overlap each other substantially completely.

Gas-operated device according to claim 1, characterized in that the fuel / air mixture increases when using butane or isobutane between an ignition setting (Z) and a final load setting (N) from about 25 to about 35.

Gas-operated device according to claim 1, characterized in that the smallest width of the throttle gap (54) is determined by a stop (52) on at least one of the end walls (40, 46).

Gas-operated device according to Claim 6, characterized in that at least three stops (52) are provided in the form of strips which enclose an angle with respect to the radial extension of the end walls (40, 46).

Gas-operated device according to claim 1, characterized in that an outer edge (42) of the end face (40) and / or the inner edge (48) in the region of the transition from the end face (46) to the mixing tube (50) are rounded with a radius (r) from 0.3 d to 1.0 d, where d is the hydraulic diameter of the mixing tube (50).

9. Gas-powered device according to claim 1, characterized in that an axial displacement of the valve member (14) in Strδ- ungs direction an increase in the gap width of the Drosselspal¬ tes (34) and a reduction in the gap width of the Drossel¬ gap (54) and an axial Displacement of the valve member (14) against the flow direction causes the opposite variation in the throttle gap widths.

10. Gas-operated device according to claim 1, characterized in that the valve member (14) by means of an actuating means (56) temperature-controlled or -regulated or time-controlled or -regulated, or is axially displaceable by hand.