Hot-air fan and method for operating the same

Abstract

The invention relates to a hot-air fan (100) comprising: a fan device (12) for producing an air stream, a heating device (14) for heating the air stream and having separately contactable heating elements (14_1,..., 14_n), a power-supply device (16), which is designed to provide electrical energy for the fan device (12) and the heating device (14), and a control unit (18), which is designed to activate the heating elements (14_1,..., 14_n), of the heating device (14) individually and supply them with electrical energy from the power-supply device (16) independently of one another.

Description

[0001] Hot air blower and method for operating the same

[0002] The invention relates to a hot air blower, in particular a battery-operated hot air hand-held device, and a method for operating the same.

[0003] A hot air blower, also called a heat gun, is a power tool used to specifically heat a work area (workpiece). For this purpose, ambient air is drawn in using a blower device such as a fan, heated by a heater, and then blown out through an outlet pipe onto the work area. The following common applications for hot air blowers are just a few examples: removing adhesive films, welding plastics, shaping plastics, removing layers of varnish or paint, especially on wood or metal, disinfecting laboratory equipment, and drying objects.

[0004] Due to the ongoing development of battery technology, particularly in the field of lithium-ion batteries, it is now possible for the first time to designate devices that were still powered exclusively by a wired external power supply at the time of registration as battery-operated handheld devices. Since the usual power output of corded hot air blowers in the range of 1600 watts to 2300 watts is not possible with battery-operated handheld blowers, but rather with power outputs in the range of 600 watts to 900 watts, the efficient conversion of electrical energy into heat-blowing power is essential for the operation of a battery-operated hot air blower. It is particularly desirable to tap into maximum power when using powerful heating devices.

[0005] In conventional battery-powered hot air guns, which operate at low continuous current, a powerful heater is regulated down using, for example, two heating coils connected in parallel. However, the maximum current peaks are so high that the heater cannot be used for all batteries.

[0006] The invention is therefore based on the object of providing a hot air blower, in particular a battery-operated handheld hot air blower, and a method for operating the same, in which maximum power can be tapped from a heating device. This object is achieved by the hot air blower according to claim 1 and by the method for operating the same according to claim 15. Advantageous embodiments and further developments of the invention are specified in the subclaims.

[0007] According to the invention, a hot air blower is provided with a blower device for generating an air flow, a heating device for heating the air flow with separately contactable heating elements, a power supply device which is designed to provide electrical energy for the blower device and the heating device, and a control unit which is designed to control the heating elements of the heating device individually and to supply them independently of one another with electrical energy from the power supply device.

[0008] This separate control of the heating elements with high overall power allows the use of low-output current battery modules as power supplies. Likewise, high-output current battery modules can be used to achieve full heating power.

[0009] The control unit 18 is designed to connect selected heating elements in parallel with the power supply device designed as a voltage source.

[0010] For example, the control unit may have an automatic switching matrix that selects the heating elements in a specific time sequence.

[0011] According to embodiments, the control unit can connect selected heating elements to the power supply device in a clock mode.

[0012] The control unit can be designed to control selected heating elements alternately during clock transitions.

[0013] Furthermore, the control unit can be designed to continuously supply a selected heating element with electrical energy within a cycle.

[0014] In particular, the control unit can be designed to supply a selected heating element with electrical energy within a cycle according to an adjustable pulse width modulation (PWM) in order to adjust the average heating power of the selected heating element.

[0015] The control unit can be designed to control selected heating elements at different times during a cycle.

[0016] The control unit can also control selected heating elements in parallel during a cycle.

[0017] The control unit can have an analog time-multiplexing method for this purpose.

[0018] Furthermore, the hot air blower can have a wireless power supply.

[0019] For example, the cordless hot air gun can be designed as a battery-operated handheld device. The power supply unit can also be designed as a battery module.

[0020] The blower device may comprise an electric motor and at least one fan wheel drivable by the electric motor for generating the air flow.

[0021] The heating device can be designed to generate a heating power (PH) in a range between 100 W and 1500 W, preferably in a range between 200 W and 1000 W, and in particular in a range between 300 W and 600 W, in a continuously adjustable manner.

[0022] The above problem is also solved by a method for operating the hot air blower described above, comprising the steps of: switching on the heating device and the blower device, and electrically connecting the heating elements to the power supply device. The heating elements are individually controlled and supplied with electrical energy independently of one another.

[0023] In particular, the heating elements can generate the same heating current when connected in parallel with the power supply device, so that this parallel connection multiplies the heating power by n times the number n of connected heating elements.

[0024] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show:

[0025] Fig. 1 : a schematic and simplified view of a hot air blower according to an embodiment of the invention,

[0026] Fig. 2: a schematic and simplified view of a heating device according to an embodiment of the invention,

[0027] Fig. 3A: a schematic representation of a control of heating elements of the

[0028] Heating device at half power according to an embodiment of the invention,

[0029] Fig. 3B: a schematic representation of a control of heating elements of the

[0030] Heating device at full power according to an embodiment of the invention,

[0031] Fig. 3C: a schematic representation of a control of heating elements of the

[0032] Heating device at 75% power according to an embodiment of the invention,

[0033] Fig. 3D: a schematic representation of a control of heating elements of the

[0034] Heating device at 2 / 3 power according to an embodiment of the invention, and

[0035] Fig. 4 : a schematic flow chart of a method for operating a hot air blower according to an embodiment of the invention.

[0036] In the figures, identical components and components with the same function are marked with the same reference numerals.

[0037] Fig. 1 shows a schematic and simplified view of a hot air blower 100 according to an embodiment of the invention. The hot air blower 100 shown in Fig. 1 has a blower device 12, a heating device 14, a power supply device 16, and a control unit 18. Furthermore, it can comprise an elongated housing 24 with an air outlet for heated air arranged at one end in the direction of a longitudinal axis L of the housing 24. This heated air is generated by the heating device 14, which heats the air sucked in by the blower device 12 via an air inlet (not shown in Fig. 1) to an operating temperature of up to approximately 700°C. This heated air can then exit through the air outlet. The operating temperature can be, for example, between 300 and 500°C.

[0038] The hot air blower 100 can have a wireless power supply. For example, the hot air blower 100 can be designed as a battery-operated handheld device. In this context, the power supply device 16 can be designed as a battery module, which can be attached or snapped into place in a known manner on the underside of a pistol-shaped handle section GFA of the hot air blower 100. The battery module can have electrical energy storage means, which are preferably designed as electrical batteries 16a.

[0039] A lithium-ion battery can be provided as the electric accumulator 16a, which, when fully charged, can be configured to operate at an operating voltage of 18 volts, 22 volts, or 36 volts. In principle, the invention is suitable for all types of electric accumulators, with the operating voltage in the fully charged state being between 5 V and 50 V, or between 10 V and 40 V, or between 15 V and 25 V.

[0040] Furthermore, the blower device 12 can have an electric motor 20 and at least one fan wheel 22 driven by the electric motor 20 to generate the air flow, as illustrated in Fig. 1. The electric motor 20 of the blower device 12 can be designed, for example, as a brush motor.

[0041] The heating device 14 has separately contactable heating elements 14_1, ... , 14_n, which are connected in parallel. This will be described in detail later with reference to Fig. 2. The heating elements 14_1, ... , 14_n can be designed as individual heating wire strands or heating wire spirals, which are accommodated, for example, in a revolver-shaped ceramic part. It is advantageous if a heating element 14n corresponds to a heating wire strand that is accommodated in a U-shape in the drum-shaped ceramic part, so that contact between the heating elements is only possible on one side, preferably the

[0042] Air inlet side, is made possible.

[0043] The power supply device 16 provides electrical energy for the blower device 12 and the heating device 14. Furthermore, the control unit 18, which is electrically connected to the blower device 12 and the heating device 14, enables control of the heating device 14 in addition to controlling the temperature of the blower device 12.

[0044] The control unit 18 controls the heating elements 14_1, ... , 14_n of the heating device 14 individually and supplies them independently of one another with electrical energy from the power supply device 16. This control makes it possible to tap maximum power from the heating device 14 with two or more heating elements 14_1, ... , 14_n designed as heating spirals.

[0045] For example, in a conventional hot air blower with parallel-connected heating coils, it is necessary to reduce the heater's power. However, this results in very high peak currents, making operation with a battery operating at a low continuous current impossible. This control method also results in a significant deviation of the effective current (RMS) from the average current (AVG).

[0046] By individually controlling the heating elements 14_1, ..., 14_n, which is described in detail below, the effective value of the current (RMS) is closer to the average current value (AVG), whereby higher power can be drawn from the accumulator module or the power supply device 16.

[0047] The control unit 18 according to the invention can connect selected heating elements 14_1, ..., 14_n in parallel to the power supply device 16 designed as a voltage source.

[0048] In this context, Fig. 2 shows a schematic and simplified view of the heating device 14 according to an embodiment of the invention. The individual heating elements 14_1, ..., 14_n can be controlled by the control unit 18 (not shown in Fig. 2) via corresponding switches S1, ..., Sn and connected to the voltage source. Using the individual switches S1, ..., Sn, it is possible, for example, to selectively select heating elements 14_1, ..., 14_n and supply them with electrical energy. The heating elements 14_1, ..., 14_n can thus be selectively connected in parallel with one another or selectively controlled individually. Selected heating elements 14_1, ..., 14_n can thus be controlled by appropriate switching combinations of the switches S1, ..., Sn can be connected in any constellation of different parallel circuits of the heating elements, whereby individually selected heating elements can also be selectively controlled without parallel connection of further heating elements.

[0049] For example, the control unit 18 can have an automatic switching matrix or an automatic switching bus that selects the heating elements 14_1, ... , 14_n in a specific chronological order. The switching unit comprising the switches S1, ... , Sn can be a transistor circuit or a field-effect transistor (FET) circuit, which can be designed, for example, as an integrated circuit (IC). In particular, the control unit 18 can connect selected heating elements 14_1, ... , 14_n to the power supply device 16 in a clock mode. Figures 3A to 3D show schematic representations of the controls of the heating elements 14_1, ... , 14_n of the heating device 14 according to embodiments of the invention. In these examples, the control of two heating elements 14_1, 14_2 is illustrated. However, additional heating elements 14_3, ... , 14_n can also be controlled accordingly.

[0050] Furthermore, Fig. 3A to 3D each show a control for a heating device 14, which has a power PH (heating power) of maximum P m ax = 600 W, for example, at an operating voltage UH of 20 V (instead of the usual 18 V or 22 V operating voltage, a charge level of the accumulator or battery with a voltage of 20 V was chosen for the purely illustrative embodiment). For two heating elements 14_1, 14_2 with the same resistance RHE = 1.33 Q, a current I flows in connection with the power supply device 16 with voltage UH. H E, which may be, for example, 15 A. The heating current IHE through a heating element 14_n is preferably between 1 A and 50 A, or between 5 A and 30 A, or between 10 A and 20 A.

[0051] The resistance of a heating element 14_n can be in a range between 0.5 Q and

[0052] 10 Q, or between 1 Q and 5 Q, or between 1 Q and 2 Q. To facilitate control, it is advantageous if the resistances of the heating elements 14_1, ..., 14_n have the same resistance value, or only differ from each other by a tolerance of 10%, or 5%, or 2%. However, the invention is not intended to be limited thereto and also functions if the heating elements 14_1, ..., 14_n are designed with different resistances.

[0053] As can be seen from Fig. 3A to Fig. 3D, the power supply device 14 can alternately drive selected heating elements 14_1, ..., 14_n during clock transitions. Here, one clock pulse in Fig. 3A to Fig. 3D corresponds to a respective column.

[0054] Fig. 3A shows a control system that enables the heating device 14 to be operated such that it generates a power PH of 300 W (i.e., a control of 50% Pmax). For this purpose, the heating elements 14_1, 14_2 can be alternately supplied with an electric current of 15 A each. In other words, only one heating element 14_1, 14_2 is connected per cycle to the power supply device 16 with UH = 20 V via switches S1, S2. The switches S1, S2 for the heating elements 14_1, 14_2 are thus switched on and off sequentially.

[0055] In Fig. 3B, however, a control is shown that enables the heating device 14 to be operated in such a way that it generates a power PH of 600 W (i.e., a control of 100% Pmax). Within one cycle, both heating elements 14_1, 14_2 are controlled in parallel or connected to the power supply device 18 by means of the switches S1, S2. The heating elements 14_1, 14_2 are thus continuously supplied with IHE = 15 A. Parallel control during one cycle with further selected heating elements 14_2, ..., 14_n (not shown in Fig. 3B) is also possible. Thus, a heating current l H of 2XIHE. The control device 18 can therefore continuously supply a selected heating element 14_1, ..., 14_n with electrical energy within one cycle.

[0056] It is also possible to supply a selected heating element 14_1, ... , 14_n with electrical energy within a cycle according to an adjustable pulse width modulation (PWM) in order to set an average heating power of the selected heating element 14_1, ... , 14_n. In this case, the control unit 18 can control selected heating elements 14_1, 14_n during a

[0057] The clock pulse can be controlled with a time offset. Examples of such control are shown in Fig. 3C and Fig. 3D.

[0058] Fig. 3C shows an example in which the heating device 14 is operated to generate a power PH of 450 W (a control of 75% Pmax). For this purpose, within a cycle, each heating element 14_1, 14_2 is controlled with a time delay and supplied with IHE = 15 A. In other words, a corresponding switch S1, S2 is closed later than the other within a cycle.

[0059] In the first cycle (first column in Fig. 3C), for example, the heating element 14_2 is connected to the power supply device 16 with a time delay by means of switch S2. The first heating element 14_1, however, is continuously supplied with IHE = 15 A within the first cycle. In the subsequent cycle, the first heating element 14_1 is connected to the power supply device 18 with a time delay, and the second heating element 14_2 is continuously supplied with IHE = 15 A. This control occurs alternately in clock mode.

[0060] In Fig. 3D a corresponding control is shown, wherein the heating device 14 is operated in such a way that it generates a power PH of 400 W (a control of 66.6% P max).

[0061] Consequently, the heating elements 14_1, ..., 14_n can be connected to the power supply device 18 one after the other until they overlap in time.

[0062] By means of this time-staggered control of the heating elements 14_1, .., 14_n, any desired additional heating outputs can be set. For this purpose, the control unit 18 can have an analog time-multiplexing method.

[0063] Consequently, with this control method, battery modules with a low output current can be used for a heating device with high overall power.

[0064] Likewise, accumulator modules with high output current can be used for a powerful heating device, thus achieving full performance. The heating device 14 can, for example, generate a continuously adjustable heating power PH in a range between 100 W and 1500 W, preferably in a range between 200 W and 1000 W, and in particular in a range between 300 W and 600 W.

[0065] Furthermore, the hot air blower 100 according to the invention covers a wider power range. The components for controlling the heating elements 14_1, ..., 14_n can have a lower power and thus be more cost-effective.

[0066] Fig. 4 shows a schematic flow chart of a method for operating the hot air blower 100 according to an embodiment of the invention.

[0067] In step S110, the heating device 14 and the blower device 12 are switched on.

[0068] In step S120, the heating elements 14_1, ..., 14_n are electrically connected to the power supply device 16.

[0069] As described above, the heating elements 14_1, ..., 14_n are controlled individually and supplied with electrical energy independently of one another.

[0070] In particular, the heating elements 14_1, ..., 14_n can generate a respective identical heating current when connected in parallel with the power supply device 16, so that by this parallel connection the heating power is multiplied n-fold in accordance with the number n of connected heating elements 14_1, ..., 14_n.

[0071] The present invention is not limited to the embodiments or operating modes shown, but rather offers numerous further and alternative setting and selection options.

Claims

Claims 1. Hot air blower (100) with - a blower device (12) for generating an air flow, - a heating device (14) for heating the air flow with separately contactable heating elements (14_1, 14_n), - a power supply device (16) which is designed to provide electrical energy for the blower device (12) and the heating device (14), and - a control unit (18) which is designed to control the heating elements (14_1, ... , 14_n) of the heating device (14) individually and to supply them independently of one another with electrical energy from the power supply device (16).

2. Hot air blower (100) according to claim 1, characterized in that the control unit (18) is designed to connect selected heating elements (14_1, ..., 14_n) in parallel with the power supply device (16) designed as a voltage source.

3. Hot air blower (100) according to claim 1 or 2, characterized in that the control unit (18) has an automatic switching matrix which selects the heating elements (14_1, ..., 14_n) in a specific chronological order.

4. Hot air blower (100) according to one of the preceding claims, characterized in that the control unit (18) is designed to connect selected heating elements (14_1, ..., 14_n) to the power supply device (16) in a clock mode.

5. Hot air blower (100) according to claim 4, characterized in that the control unit (18) is designed to control selected heating elements (14_1, ..., 14_n) alternately during clock transitions.

6. Hot air blower (100) according to claim 4 or 5, characterized in that the control unit (18) is designed to continuously supply a selected heating element (14_1, ..., 14_n) with electrical energy within a cycle.

7. Hot air blower (100) according to claim 4 to 6, characterized in that the control unit (18) is designed to supply a selected heating element (14_1, ..., 14_n) with electrical energy within a cycle according to an adjustable pulse width modulation, PWM, in order to adjust the average heating power of the selected heating element (14_1, ..., 14_n).

8. Hot air blower (100) according to claims 4 to 7, characterized in that the control unit (18) is designed to control selected heating elements (14_1, ..., 14_n) with a time offset during a cycle.

9. Hot air blower (100) according to claim 4 to 7, characterized in that the control unit (18) is designed to control selected heating elements (14_1, ..., 14_n) in parallel during one cycle.

10. Hot air blower (100) according to one of the preceding claims, characterized in that the control unit (18) has an analog time-multiplexing method.

11. Hot air blower (100) according to one of the preceding claims, characterized in that the hot air blower (100) has a wireless power supply.

12. Hot air blower (100) according to claim 11, characterized in that the cordless hot air blower (100) is designed as a battery-operated hand-held device, wherein the power supply device (16) is designed as a battery module.

13. Hot air blower (100) according to one of the preceding claims, characterized in that the blower device (12) comprises an electric motor (20) and at least one fan wheel (22) drivable by means of the electric motor (20) for generating the air flow.

14. Hot air blower (100) according to one of the preceding claims, characterized in that the heating device (14) is designed to generate a heating power (PH) in a range between 100 W and 1500 W, preferably in a range between 200 W and 1000 W, and in particular in a range between 300 W and 600 W, in a continuously adjustable manner.

15. Method (1000) for operating a hot air blower (100) according to one of the preceding claims, comprising the steps - switching on (S110) the heating device (14) and the blower device (12), and - electrically connecting (S120) the heating elements (14_1, ... , 14_n) to the power supply device (16), wherein the heating elements (14_1, ... , 14_n) are individually controlled and supplied with electrical energy independently of one another.

16. The method (1000) according to claim 15, wherein the heating elements (14_1, ... , 14_n) generate a respective identical heating current when connected in parallel to the power supply device (16), so that this parallel connection multiplies the heating power n-fold according to the number n of connected heating elements (14_1, ... , 14_n).

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