Method for controlling a hair dryer and hair dryer

Abstract

A control method for a hair dryer (1) comprises the steps of manually activating said hair dryer (step C1); powering an electric motor (5) and heating means (7) with respective operating electrical powers (Pmo, Pro) to generate a flow of hot air having a defined operating temperature (To) (step S1); detecting a temperature inside the heating means (7) via a sensor (8) and comparing a measured temperature (Tm) detected by the sensor (8) with a defined maximum temperature (Tmax) (step S1); if the measured temperature (Tm) is equal to or greater than the maximum temperature (Tmax), activating a recovery procedure (step S2) comprising the steps of powering the heating means (7) with a recovery electrical power (Prr) lower than the respective operating electrical power (Pro) to reduce a temperature of the heating means (7); activating a timer to measure an intervention time (ti), wherein the measured temperature (Tm) is greater than a defined recovery temperature (Tr); incrementing a secondary counter (Cb) by one unit; if and when the measured temperature (Tm) is lower than or equal to the recovery temperature (Tr), if the intervention time (ti) is lower than or equal to a first time (t1) or if the intervention time (ti) is lower than or equal to a second time (t2) and the secondary counter (Cb) is lower than or equal to N, resetting the intervention time (ti) (step S3) and powering the heating means (7) with the respective operating electrical power (Pro) (step S1); if the intervention time (ti) is greater than the first time (t1) or if the intervention time (ti) is greater than the second time (t2) and the secondary counter (Cb) is greater than N, generating an alarm signal (ALL0) (step S4); in the latter case, if the intervention time (ti) is lower than a third time (t3), resetting the intervention time (ti) and stopping the alarm signal (ALL0) (step S3) and then supplying the heating means (7) with the operating electrical power (Pro) (step S1); or if the intervention time (ti) is greater than or equal to the third time (t3), interrupting the electrical supply to the heating means (7) and the electric motor (5) and resetting and generating a first coded alarm signal (ALL1) (step S6).

Description

[0001] Method for controlling a hair dryer and hair dryer

[0002] The present invention relates to hair dryers and in particular to a method for controlling the operation of a hair dryer. The invention also relates to a hair dryer that implements such a control method.

[0003] Well-known and widely used hair dryers on the market, and in particular portable hair dryers intended for both professional and household use, are electrical apparatuses having an outer casing commonly made of plastic material, provided with a handle and a hollow body defining a through-air duct.

[0004] In the most common embodiment, an electric motor, a centrifugal or axial fan connected to and rotated by the electric motor, and one or more electric heating elements, in particular resistors or electrical resistances for heating the air, are housed inside the casing of the hair dryer, more specifically in the internal cavity forming the air duct.

[0005] When the apparatus is in use, that is, when the electric motor and the electrical heating resistances are electrically powered, the fan is rotated by the electric motor and generates inside the air duct a flow of air, which is sucked at the rear of the hair dryer through a suction opening, flows towards the hair dryer frontal part and exits through a frontal opening or outlet. The air flow passes through electrical heating resistances, which, as the electric current passes therethrough, release the heat generated by the Joule effect into the air thereby heating it.

[0006] The electrical heating resistances are powered by the electric current in an adjustable way according to the user's requirements so as to have different hot air temperature values.

[0007] In normal operation of the hair dryer, the air flow generated by the fan ensures at all user- selectable speeds of rotation of the electric motor that the temperature of the heating elements remains within a predefined range, particularly that it does not exceed a maximum value. However as a result of prolonged use of the hair dryer or due to an unforeseen and excessive decrease in the air flow generated by the fan, typically as a result of partial or complete obstruction of the air suction opening, the temperature of electrical resistances may rise excessively, which may cause problems of excessive heating of the outer casing of the apparatus as well as the electrical resistances themselves and the electric motor. Such excessive heating or overheating in addition to damaging the components of the hair dryer (electric heating elements, motor, etc.) may be dangerous to the safety of the user.

[0008] In order to prevent an excessive and uncontrolled rise in the temperature of electrical resistances, there are known hair dryers that are generally provided with a thermostat designed to cut off the power supply to the electrical resistances when a predefined threshold or intervention temperature is reached, in particular by preventing the complete shutdown of the apparatus provided for safety reasons when a defined maximum temperature is reached. The thermostat is directly inserted in series in the electric circuit powering the electrical resistances so that upon the occurrence of an abnormal condition, which causes the temperature to rise up to the defined threshold or intervention value, the thermostat intervenes by interrupting the power supply to the electrical resistances, this resulting in a progressive decrease in their temperature. The motor is generally kept running to continue generating the air flow that cools off the electrical resistances.

[0009] Once the temperature value of the electrical resistances has fallen below the intervention value, the thermostat reopens the electric current flow to the electrical resistances.

[0010] Although the presence of a thermostat does indeed allow intervention in case of excessive overheating, the use of a traditional thermostat, e.g. of the air-sensing, contact, bulb, thermocouple or magnetic type, has some disadvantages.

[0011] In fact, if said predetermined value of the intervention temperature is selected so as to be too close to the damage value of the hair dryer electrical resistances, the intervention of the thermostat may be belated to preserve the structural integrity of the hair dryer electrical resistances.

[0012] On the other hand, if said predetermined intervention temperature value is selected so as to be too close to the optimal operating value of the electrical resistances, the result obtained is that of having a frequent and cyclical intervention of the thermostat that, by interrupting the electrical supply to the electrical resistances, determines an anomalous lowering of the air temperature, with a subsequent reactivation of the electrical resistances and a possible subsequent interruption, i.e. an on / off type power supply of the electrical resistances, which causes the emission of a flow of hot air at a non-constant temperature.

[0013] As is well known, thermostat interventions typically become more frequent as the air filter located at the suction opening of the apparatus is clogged and dirty, thus hindering the suction of air from the outside environment.

[0014] An object of the present invention is to provide a control method for hair dryers that allows to overcome the operational disadvantages of known hair dryers.

[0015] Another object is to provide a control method that allows to precisely and promptly control the temperature of the electrical resistances of the hair dryer, by preventing exceeding a maximum safety temperature.

[0016] A further object is to provide a control method that allows the hair dryer to deliver a flow of hot air at an almost constant temperature, even during prolonged use of the apparatus and / or in the event of an abnormal condition or abnormal use of the apparatus itself.

[0017] A further object is to provide a control method that allows monitoring the operation of the hair dryer and reporting to the user any abnormal behavior and / or the need for maintenance interventions.

[0018] A further object is to provide a hair dryer that is economical and having a reliable and safe operation.

[0019] According to a first aspect of the invention it is provided a control method for hair dryers according to claim 1.

[0020] According to a second aspect of the invention, it is provided a hair dryer according to claim

[0021] 13.

[0022] The invention can be better understood and implemented with reference to the attached drawings, which illustrate an exemplifying and non-limiting embodiment, wherein:

[0023] - Figure l is a section of a portable hair dryer according to the invention;

[0024] - Figure 2 is a block diagram illustrating the operating steps of the control method for hair dryer of the invention.

[0025] With reference to figure 1, a blow dryer or hair dryer 1 according to the present invention is illustrated, which comprises a casing 2 provided with a main body 3 having a central duct 12 communicating with a rear suction first opening 13 and a front supply second opening

[0026] 14. The casing 2 also comprises a handle 4.

[0027] The central duct 12 extends longitudinally along and inside the main body 3 so as to have at its ends the first opening 13 for the suction and the second opening 14 for the supply of an air flow.

[0028] The hair dryer 1 also comprises an electric motor 5 and a fan 6 positioned inside the main body 3. The fan 6 can be rotated by the electric motor 5 to generate the air flow inside the central duct 12 flowing from the first opening 13 to the second opening 14.

[0029] The hair dryer 1 is also provided with heating means 7 arranged inside the main body 3 in the central duct 12, for example at the second opening 14, and arranged to heat the air flow generated by the fan 6.

[0030] The heating means 7 comprise one or more resistive elements or electrical resistances of a known type capable of generating heat by Joule effect when crossed by an electric current. The hair dryer 1 is provided with a temperature sensor 8, positioned inside the main body 3 and capable of measuring a temperature of the heating means 7, and control unit 10 of a known type capable of managing and controlling the operation of the hair dryer, and in particular configured to regulate the electrical power supplies Pm, Pr of the electric motor 5 and of the heating means 7 and to receive from the temperature sensor 8 a signal relating to a measured temperature Tm. The control unit 10, in particular, is configured to implement the control method according to the invention described below.

[0031] The hair dryer 1 is also provided with signaling means 16, 17, connected to and controlled by the control unit 10 and arranged to emit light and / or sound signals relating to an alarm signal ALL and / or coded alarm signals ALLI, ALL2, ALL3 generated by the control unit 10 during operation. The signaling means comprise for example one or more LEDs 16 and / or an acoustic signaller 17. The LEDs 16 and the acoustic signaller are mounted on the handle 4 of the hair dryer 1, for example.

[0032] An on / off button 15 is provided on the handle 15 to enable a user to turn the hair dryer 1 on or off, in particular to activate / deactivate the control unit 10 that manages the operation of the hair dryer 1 and more specifically to implement, during operation, the control method of the invention that comprises the following steps: manually activating the hair dryer 1 (step C 1), in particular by pressing the power button 15; electrical powering the electric motor 5 and the heating means 7 with respective operating electrical powers Pmo, Pro in order to generate a flow of hot air having a defined operating temperature To (step SI); detecting, in particular continuously or with a defined measurement frequency during said electrical powering, a temperature of the heating means 7 by means of the sensor 8 (step SI) and comparing a measured temperature Tm detected by the sensor 8 with a defined maximum temperature Tmax (step SI), in particular saved in the control unit 10; if the measured temperature Tm is equal to or greater than the maximum temperature Tmax (Tm > Tmax), activating a recovery procedure (step S2) that comprises: o electrical powering the heating means 7 with a respective recovery electrical power Prr lower than the respective operating electrical power Pro in order to reduce a temperature of said heating means 7; o activating a clock or timer to measure an intervention time or interval ti in which the measured temperature Tm is greater than a defined recovery temperature Tr (Tm > Tr), which is lower than or equal to the maximum temperature Tmax, for example; o incrementing a secondary counter Cb by one unit (Cb=Cb+l); if and when the measured temperature Tm is lower than or equal to the defined recovery temperature Tr (Tm < Tr), o if the intervention time ti is lower than or equal to a first time tl (ti < tl) or if the intervention time ti is lower than or equal to a second time t2 and the secondary counter Cb is lower than or equal to N (with N being an integer greater than 1) (tl < t2 and Cb < N), resetting the intervention time ti (ti = 0) (step S3) and then electrically supplying the heating means (7) with the respective operating electrical power (Pro) (step SI); or o if the intervention time ti is greater than the first time tl (ti > tl) or if the intervention time ti is greater than the second time t2 and said secondary counter Cb is greater than N (tl > t2 and Cb > N), generating an alarm signal ALLO (ALLO on), increasing a primary counter (Ca) by one unit and saving its value in the control unit (10) (step S4) and

[0033] ■ if the intervention time ti is lower than a third time t3 (ti > t3), resetting the intervention time ti (ti =0) and stopping the alarm signal ALLO (ALLO off) (step S3) and then electrically powering the heating means (7) with the respective operating electrical power (Pro) (step SI); or

[0034] ■ if the intervention time ti is greater than or equal to the third time t3 (tl > t3), stopping said electrical powering the heating means 7 and the electric motor 5 and resetting the intervention time ti and the primary counter Ca (step S5) and then generating a first coded alarm signal ALLI (ALLI on) (step S6).

[0035] In particular, the first time tl is greater than the second time t2 and lower than the third time t3. For example, tl is equal to 5 s, t2 is equal to 3 s, t3 is equal to 20 s. The integer N is for example equal to 3.

[0036] The electrical recovery power Prr is for example lower than 40-60% of the operating electrical power Pro of the heating means 7.

[0037] The recovery temperature Tr is for example lower than 10-20% at the maximum temperature Tmax.

[0038] It should be noted that if the intervention time ti is lower than or equal to the first time tl (5s) or if the intervention time ti is lower than or equal to the second time t2 (3s) and the secondary counter Cb is lower than or equal to N (3), the recovery procedure (step S2) has been activated due to an irregular and limited variation in the temperature of the heating means 7 and there is no need for it to be communicated to the user by generating an alarm signal. On the contrary, if the intervention time ti is greater than the first time tl (5s) or if the intervention time ti is greater than the second time t2 (3s) and the secondary counter Cb is greater than N (i.e., the heating means 7 have already exceeded the maximum temperature Tmax), it is necessary to warn the user of the activation of the recovery procedure since the temperature rise of the heating means 7 during operation may be due to a decrease in the air flow caused by a partial and / or temporary occlusion of the suction opening 13 due to a clogged suction opening filter, or due to improper use of the hair dryer 1 (partial or total occlusion of the suction opening 13 made by the user to regulate the air flow).

[0039] To be noted that in the event that during the use of the hair dryer 1 the recovery procedure has been carried out a number of times greater than N (3), counted by the secondary counter Cb, the first coded alarm signal ALLI (ALLI on) (step S6) is generated and the primary counter Ca is increased by one unit as soon as the intervention time exceeds the second time t2 which is lower than the first time tl to safeguard the heating means 7 and the whole apparatus.

[0040] The control method may also provide to progressively decrease the recovery electrical power Prr of the heating means 7, particularly at regular intervals and discrete quantities, up to a defined minimum value, for example equal to zero. For example, a first initial value of the recovery power Prr may be equal to 50% of the operating electrical power Pro of the heating means 7 and this value may in turn be reduced by 25% at intervals of n seconds until it assumes a zero value, for example after a time equal to the third time t3.

[0041] In addition, the control method includes, after the execution of the first coded alarm signal ALLI (step S6), to completely turn off the hair dryer 1 (step S7) specifically by cutting off the power supply to all components and control unit 10.

[0042] The control method includes, during the execution of the first coded alarm signal ALLI (step S6), to manually turn off the hair dryer 1 (step C2) specifically by manually acting on the on / off button 15 so as to stop the first coded alarm signal ALLI (step S8) and turn off the hair dryer 1 (step S7), specifically by shutting off the power supply to all components and the control unit 10.

[0043] The first coded ALLI alarm signal is a first defined sequence of nl repetitions, e.g., ten, of flashes of LED 16 and / or repeated sounds made by the acoustic signaller 17.

[0044] Similarly, the ALLO alarm signal is a continuous succession of flashes of LED 16 and / or repeated sounds from the acoustic signaller 17.

[0045] During step S5, it is provided to interrupt the electrical power supply of the electric motor 5 after a defined cooling time Traf, for example between 10 and 15s, to allow the air flow generated by the fan 6, driven by the motor 5, to internally cool off the hair dryer 1.

[0046] The control method also comprises, after said activating step (step Cl) and before or during said powering step (step SI), to generate a second coded alarm signal ALL2 (ALL2 on) (step S9) if the value of primary counter Ca saved in control unit 10 is greater than or equal to 1 and then to reset primary counter Ca.

[0047] The value greater than 1 of the primary counter Ca is greater than 1 if during the previous use of the hair dryer 1 there was at least one episode of temperature rise of the heating means 7 above the maximum temperature Tmax which determined the activation of the recovery procedure S2.

[0048] Since the temperature rise of the heating means 7 during operation can be attributable to a decrease in the air flow due to a partial and / or temporary occlusion of the suction opening 13, the second coded alarm signal ALL2 emitted when the hair dryer 1 is switched on, reminds the user to check the filter of the suction opening 13 so as to verify whether it is clogged or dirty or to avoid partially or totally occluding the suction opening 13 during use (for example to atypically adjust the air flow).

[0049] The second coded ALL2 alarm signal is a second defined sequence of n2 repetitions, e.g., one, of flashes of LED 16 and / or repeated sounds made by the acoustic signal 17.

[0050] The control method provides to manually deactivate the hairdryer (1) (step C2) to turn it off (step S7) during operation of the hair dryer, i.e. during said powering and detecting (step SI), in particular by manually acting on the on / off button 15 in order to interrupt the electrical power supply to all the components and the control unit 10.

[0051] After said manually deactivating step (step C2) and before said step of turning off the hair dryer 1, there is provided to generate a third coded alarm signal ALL3 (step SI 1) if the value of the primary counter Ca saved in the control unit is greater than or equal to 1.

[0052] Also in this case, the third ALL3 coded alarm signal emitted during the shutdown of the hair dryer 1 reminds the user that during the use the recovery system has come into operation to limit the temperature rise of the heating means 7 and that it is therefore necessary to check the filter of the suction opening to verify whether it is clogged or dirty and / or whether it is advisable to avoid partially or totally blocking the suction opening 13 during the use (to atypically regulate the air flow).

[0053] The third coded alarm signal ALL3 is a third defined sequence of n3 repetitions, e.g., three, of flashes of LED 16 and / or of repeated sounds emitted by the acoustic signallerl7.

[0054] The control method also provides, after said manually turning off step (step C2) and before said step of turning off the hair dryer 1, to reset the secondary counter Cb (step S10).

[0055] In a variant of the control method of the invention, it is provided that the recovery procedure (step S2) also comprises electrical powering the electric motor 5 with a recovery electrical power Pmr greater than the respective operating power Pmo so as to increase the air flow generated by the fan 6 and contribute to reducing the temperature of the heating means 7. In particular, the recovery electrical power Pmr is greater than 10-20% of the respective operating power Pmo.

[0056] The control method of the invention implemented on a hair dryer provided with a control unit 10 thus allows, during use, to precisely and timely control the temperature of the heating means 7, i.e., the electrical heating elements, in particular it allows to avoid exceeding a maximum safety temperature by avoiding a complete shutdown of the apparatus, but automatically reducing the electrical power supplied to the heating means 7. Once the temperature of the heating means 7 has been brought back above the recovery temperature Tr, the control unit 10 restores the operating power supply to the heating means. Due to the small difference between the maximum temperature and the recovery temperature (which can also coincide with the maximum temperature) the recovery procedure is generally very rapid which allows the hair dryer 1 to deliver a flow of hot air at an almost constant temperature, even during prolonged use of the apparatus and / or in the event of an anomalous condition or abnormal use of the apparatus itself.

[0057] In addition, the control method of the invention allows to monitor the operation of the hair dryer and to notify the user of anomalous behavior and / or the need for maintenance interventions. In particular, as already underlined, the activation of the recovery procedure for a duration longer than a certain time is signaled to the user during operation, when the hair dryer 1 is turned off and then turned on again, to report that an abnormal rise in the temperature of the heating media 7 has occurred during operation attributable to a decrease in air flow as a result of a partial and / or temporary occlusion of the suction opening 13, due to a clogged suction opening filter, or a non-compliant use of the hair dryer 1 (partial or total occlusion of the suction opening 13 made by the user to regulate air flow).

Claims

CLAIMS1. Control method for controlling a hair dryer (1) that comprises an electric motor (5) and a fan (6) rotationally driven by said electric motor (5) to generate an air flow, air heating means (7), a control unit (10) for regulating an electric power supply of said electric motor (5) and said heating means (7), a temperature sensor (8) for measuring a temperature of said heating means (7), said method comprising the steps of: manually activating said hairdryer (step Cl); powering said electric motor (5) and said heating means (7) with respective operating electrical powers (Pmo, Pro) in order to generate a flow of hot air having a defined operating temperature (To) (step SI); and detecting a temperature of said heating means (7) by means of said sensor (8), comparing a measured temperature (Tm) detected by said sensor (8) with a defined maximum temperature (Tmax) (step SI); if said measured temperature (Tm) is equal to or greater than said maximum temperature (Tmax), activating a recovery procedure (step S2) that comprises: o powering said heating means (7) with a recovery electrical power (Prr) lower than the respective operating electrical power (Pro) in order to reduce a temperature of said heating means (7); o activating a timer to measure an intervention time (ti) in which said measured temperature (Tm) is greater than a defined recovery temperature (Tr), which is lower than or equal to said maximum temperature (Tmax); o increasing a secondary counter (Cb) by one unit; if and when said measured temperature (Tm) is lower than or equal to said defined recovery temperature (Tr), o if said intervention time (ti) is lower than, or equal to, a first time (tl) or if said intervention time (ti) is lower than or equal to a second time (t2) and said secondary counter (Cb) is less than or equal to N, where N is an integer greater than 1, resetting said intervention time (ti) (step S3) and then powering said heating means (7) with said operating electrical power (Pro)o(step SI); o if said intervention time (ti) is greater than the first time (tl) or if said intervention time (ti) is greater than the second time (t2) and said secondary counter (Cb) is greater than N, generating an alarm signal (ALLO), increasing a primary counter (Ca) by one unit and saving the value thereof in the control unit (10) (step S4) and■ if said intervention time (ti) is lower than a third time (t3), resetting said intervention time (ti) and stopping the alarm signal (ALLO) (step S3) and then powering said heating means (7) with the respective operating electrical power (Pro) (step SI); or■ if said intervention time (ti) is greater than or equal to said third time (t3), stopping said powering said heating means (7) and said electric motor (5) and resetting said intervention time (ti) and said primary counter (Ca) (step S5) and then generating a first coded alarm signal (ALLI) (step S6).

2. Control method according to claim 1, comprising after generating said first coded alarm signal (ALLI) (step S6), fully turning off said hair dryer (1) (step S7).

3. Control method according to claim 1, comprising during said generating the first coded alarm signal (ALLI) (step S6) manually deactivating said hair dryer (1) (step C2), stopping said first coded alarm signal (ALLI) (step S8) and turning off said hairdryer (1) (step S7).

4. Control method according to any preceding claim, comprising after said activating (step Cl) and before or during said powering (step SI) generating a second coded alarm signal (ALL2) (step S9) if a value of said primary counter (Ca) saved in said control unit (10) is higher than or equal to 1 and then resetting said primary counter (Ca).

5. Control method according to any preceding claim, comprising during said powering and said detecting (step SI), manually deactivating said hair dryer (1) (step C2) in order to turn off said hair dryer (1) (step S7).

6. Control method according to claim 5, comprising after said manually deactivating (step C2) and before turning off said hair dryer (1) generating a third coded alarm signal (ALL3) (step SI 1) if the value of said primary counter (Ca) saved in said control unit is higher than or equal to 1.

7. Control method according to claim 5 or 6, comprising after said manually deactivating (step C2) and before said turning off said hair dryer (1) resetting said secondary counter (Cb) (step S10).

8. Control method according to any preceding claim, comprising progressively decreasing said recovery electrical power (Prr), in particular at regular intervals of discrete quantities, up to a defined minimum value.

9. Control method according to any preceding claim, wherein said recovery procedure (step S2) comprises powering said electric motor (5) with a recovery electrical power (Pmr) greater than the respective operating electrical power (Pmo) in order to increasean air flow generated by the fan (6).

10. Control method according to any preceding claim, comprising interrupting said powering said electric motor (5) after a defined cooling time (Traf) so as to allow the air flow generated by the fan (6) to internally cool said hair dryer (1) (step S5).

11. Control method according to any preceding claim, wherein said generating an alarm signal (ALLO) and / or a coded alarm signal (ALLI, ALL2, ALL3) comprises generating light and / or sound signals via signaling means (16, 17) of said hairdryer (1).

12. Control method according to any preceding claim, wherein said first time (tl) is equal to 5 s, said second time (t2) is equal to 3 s, said third time (t3) is equal to 20 s and N is equal to 3.

13. Hairdryer (1) comprising:- a casing (2) provided with a main body (3) having a central duct (12) communicating with a rear suction first opening (13) and a front supply second opening (14);- an electric motor (5) and a fan (6) positioned inside said main body (3), said fan (6) being rotated by said electric motor (5) so as to generate an air flow in the central duct (12) flowing from said first opening (13) to said second opening (14);- heating means (7) arranged inside said main body (3) to heat said air flow;- a temperature sensor (8) positioned inside said main body (3) to measure a temperature of said heating means (7); and- a control unit (10) configured to regulate electric power supplies of said electric motor (5) and said heating means (7) and to receive from said temperature sensor (8) a signal relating to a measured temperature (Tm), wherein said control unit (10) is configured to implement the control method according to any preceding claim.

14. Hairdryer (1) according to claim 12, comprising signaling means (16, 17) for emitting light and / or sound signals relating to an alarm signal (ALL) and / or a coded alarm signal (ALLI, ALL2, ALL3) generated during operation.

15. Hairdryer (1) according to claim 13, wherein said signaling means comprise at least one LED (16) and / or an acoustic signaler (17).

16. Hairdryer (1) according any of claims 12 to 15, wherein said heating means (7) comprise at least one electric resistance suitable for generating heat when powered by an electrical power supply.

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