Dryer with universal voltage controller

Abstract

A hand dryer comprising a universal brushed AC blower vacuum motor, one or more resistive circuits of a heating element, and a universal voltage controller that selectively alternates the configuration and the electrical connection of the resistive circuits, in response to a detected input voltage is disclosed.

Claims

1. A hand dryer configured to accept multiple voltage inputs, the hand dryer comprising: a blower vacuum motor for producing output air; a heating element for heating the output air, the heating element comprising a plurality of resistors configured to form a plurality of resistive circuits, each of the plurality of resistive circuits in one of series and parallel with the blower vacuum motor; and a voltage controller for selecting a nominal voltage supplied to the blower vacuum motor via the plurality of resistors of the heating element, the voltage controller selecting the nominal voltage based on an input voltage by operating one or more relays to independently select one of the plurality of resistive circuits.

2. The hand dryer as recited in claim 1, wherein the plurality of resistive circuits comprises a first resistive circuit, a second resistive circuit, and a third resistive circuit, and the plurality of resistors comprises a first resistor and a second resistor.

3. A hand dryer configured to accept multiple voltage inputs, the hand dryer comprising: a blower vacuum motor for producing output air; a heating element for heating the output air, the heating element comprising a first resistor and a second resistor; a voltage controller for selecting a nominal voltage supplied to the blower vacuum motor, the voltage controller selecting the nominal voltage based on an input voltage by operation of one or more relays to select a first resistive circuit, a second resistive circuit, or a third resistive circuit; the first resistive circuit has the first resistor and the second resistor in series with each other and in parallel with the blower vacuum motor; the second resistive circuit has the first resistor in series with the blower vacuum motor and the second resistor is not in series with the blower vacuum motor; and the third resistive circuit has the first resistor and the second resistor in series with the blower vacuum motor.

4. The hand dryer as recited in claim 3, wherein the first resistive circuit has a first circuit resistance and the second resistive circuit has a second circuit resistance, the second circuit resistance being greater than the first circuit resistance.

5. The hand dryer as recited in claim 3, wherein the first resistive circuit has a first circuit resistance and the second resistive circuit has a second circuit resistance, the second circuit resistance being at least ten ohms greater than the first circuit resistance.

6. The hand dryer as recited in claim 3, further comprising a switch that selectively actuates the one or more relays to select the first resistive circuit, the second resistive circuit, or the third resistive circuit.

7. The hand dryer as recited in claim 6, further comprising a processor configured to control embedded software that actuates the switch.

8. The hand dryer as recited in claim 6, wherein the one or more relays comprise at least three relays.

9. The hand dryer as recited in claim 3, wherein the input voltage has an alternating current (AC) waveform that is maintained in the first resistive circuit, in the second resistive circuit, and in the third resistive circuit.

10. The hand dryer as recited in claim 3, wherein the second resistive circuit has a second circuit resistance equal to a first resistance of the first resistor.

11. The hand dryer as recited in claim 10, wherein the third resistive circuit has a third circuit resistance equal to a sum of the first resistance of the first resistor and a second resistance of the second resistor.

12. The hand dryer as recited in claim 3, wherein the one or more relays are configured to select a resistive circuit from a group consisting of the first resistive circuit, the second resistive circuit, and the third resistive circuit.

13. The hand dryer as recited in claim 3, wherein the second resistive circuit has a second circuit resistance (RE.sub.2) given by: ${\mathrm{RE}}_2=\mathrm{RM}\left(\frac{\mathrm{VS}}{\mathrm{VM}}-1\right)$ where RM=a dynamic resistance of the blower vacuum motor; VS=the input voltage; VM=the nominal voltage to be supplied to the blower vacuum motor, and RE.sub.2 is equal to a first resistance of the first resistor.

14. The hand dryer as recited in claim 13, wherein the third resistive circuit has a third circuit resistance (RE.sub.3) given by: ${\mathrm{RE}}_3=\mathrm{RM}\left(\frac{\mathrm{VS}}{\mathrm{VM}}-1\right)$ where RM=the dynamic resistance of the blower vacuum motor; VS=the input voltage; VM=the nominal voltage to be supplied to the blower vacuum motor, and RE.sub.3 is equal to a sum of the first resistance of the first resistor and a second resistance of the second resistor.

15. The hand dryer as recited in claim 14, wherein the input voltage (VS) is selected from the group consisting of 120 VAC, 208 VAC, 240 VAC and 277 VAC.

16. The hand dryer comprising: a blower vacuum motor for producing output air, the blower vacuum motor having a dynamic resistance; a heating element for heating the output air, the heating element comprising a first resistor and a second resistor; a voltage controller for selecting a nominal voltage supplied to the blower vacuum motor, the voltage controller selecting the nominal voltage based on an input voltage by operation of one or more relays to select a first resistive circuit, a second resistive circuit or a third resistive circuit; the first resistive circuit has the first resistor and the second resistor in series with each other and in parallel with the blower vacuum motor; the second resistive circuit has the first resistor in series with the blower vacuum motor and the second resistor is not in series with the blower vacuum motor and the second resistive circuit has about a 0.7:1 resistance ration with the dynamic resistance of the blower vacuum motor; and the third resistive circuit has the first resistor and the second resistor in series with the blower vacuum motor and the third resistive circuit has about a 1:1 resistance ratio with the dynamic resistance of the blower vacuum motor.

17. The hand dryer as recited in claim 16, where the second circuit has a second circuit resistance (RE.sub.2) given by: ${\mathrm{RE}}_2=\mathrm{RM}\left(\frac{\mathrm{VS}}{\mathrm{VM}}-1\right)$ where RM=a dynamic resistance of the blower vacuum motor; VS=the input voltage; VM=the nominal voltage to be supplied to the blower vacuum motor, and RE.sub.2 is equal to a first resistance of the first resistor.

18. The hand dryer as recited in claim 17, wherein the third resistive circuit has a third circuit resistance (RE.sub.3) given by: ${\mathrm{RE}}_3=\mathrm{RM}\left(\frac{\mathrm{VS}}{\mathrm{VM}}-1\right)$ where RM=the dynamic resistance of the blower vacuum motor; VS=the input voltage; VM=the nominal voltage to be supplied to the blower vacuum motor, and RE.sub.3 is equal to a sum of a first resistance of the first resistor and a second resistance of the second resistor.

19. The hand dryer as recited in claim 16, wherein the input voltage is selected from the group consisting of 120 VAC, 208 VAC, 240 VAC and 277 VAC.

20. The hand dryer as recited in claim 16, wherein the nominal voltage to be supplied to the blower vacuum motor is 120 VAC and the input voltage is selected from the group consisting of 208 VAC, 240 VAC and 277 VAC.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of the invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which:

(2) FIG. 1 illustrates a cross section of an exemplary hand dryer for use with embodiments disclosed herein;

(3) FIG. 2 illustrates a portion of an exemplary universal voltage controller;

(4) FIG. 3 illustrates an exemplary table of relay activation conditions corresponding to different input voltages;

(5) FIG. 4 illustrates a universal voltage controller in a first resistive circuit with two heating elements in series with each other and in parallel with a motor;

(6) FIG. 5 illustrates a universal voltage controller in a second resistive circuit with one resistive circuit in series with the motor; and

(7) FIG. 6 illustrates a universal voltage controller in a third resistive circuit with two resistive circuits in series with the motor.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1 discloses a hand dryer 100 incorporating a universal brushed AC blower vacuum motor 102, a heating element 104 comprising one or more resistive circuits for heating the output air and a universal voltage controller 200 (see FIG. 2) that selects the nominal voltage supplied to the blower vacuum motor 102 through switching relay(s). The relay(s) select resistors of the resistive circuits to be electrically connected in series or parallel with the blower vacuum motor 102. The heating element 104 is disposed between a pressure-side 106 of the blower vacuum motor 102 and a hand dryer outlet 108 for the drying air as shown in FIG. 1.

(9) In one embodiment, the universal brushed AC blower vacuum motor 102 is designed and manufactured for a nominal input supply voltage of 120 VAC with an input power ranging from 500-1200 watts. The one or more resistive circuits of the heating element 104 are sized in electrical resistance to develop a specific ratio with the dynamic resistance of the blower vacuum motor 102. In one embodiment, one resistive circuit of the heating element 104 is sized to create a 1:1 ratio with the dynamic resistance of the blower vacuum motor 102. In one embodiment, a second resistive circuit of the heating element 104 is sized to create a ratio of 0.733 with the dynamic resistance of the blower vacuum motor 102. Another resistive circuit places the resistors in parallel with the blower vacuum motor 102.

(10) As shown in FIG. 2, the universal controller 200 includes a switch, such as a simple electro-mechanical relay or other acceptable switching device, to control the switching of the relay(s) for the one or more resistive circuits to connect resistors in parallel or in series with the blower vacuum motor 102. In some embodiments, the universal voltage controller 200 detects the input voltage using embedded software for controlling the switch. The embedded software may be controlled by a processor.

(11) In the embodiment where a universal brushed AC blower vacuum motor 102 is designed for an input voltage of 120 VAC, a resistive circuit of the heating element 104 with a 1:1 ratio of resistance to the dynamic resistance of the blower vacuum motor 102 is employed. The resistive circuit is configured to be in parallel with the blower vacuum motor 102 when the input voltage is 120 VAC. When the input voltage is 240 VAC, the universal voltage controller 200 will detect the input voltage and the embedded software will cause the resistive circuit of the heating element 104 to be in electrical series with the blower vacuum motor 102. In this instance, the voltage potential across the resistive circuit of the heating element 104 will be half of the input supply voltage and the voltage supplied to the blower vacuum motor 102 will be half of the input voltage (e.g. 120 VAC nominal). When connected electrically in series with the blower vacuum motor 102, the resistive circuit of the heating element 104 provides heat energy for warming the output air for user comfort and adjusts the input voltage supplied to the blower vacuum motor 102. When connected electrically in parallel with the blower vacuum motor 102, the resistive circuit of the heating element 104 will only function to warm the output air for user comfort.

(12) In one embodiment, the heating element 104 has two resistive circuitsa first resistive circuit with a 1:1 ratio of resistance to the dynamic resistance of the blower vacuum motor and a second resistive circuit with a ratio of 0.733 with the dynamic resistance of the blower vacuum motor. In this embodiment, when the input power supply is 120 VAC, the universal controller will detect the input voltage and the embedded software will cause resistors of the resistive circuit to be electrically connected in parallel with the control circuit of the blower vacuum motor 102. When the input voltage is 240 VAC, the universal voltage controller 200 will detect the input voltage and the embedded software will cause the resistors of the resistive circuit of the resistive circuit of the heating element 104 to be in electrical series with the blower vacuum motor 102. When the input voltage is 208 VAC, the universal voltage controller 200 will detect the input voltage and the embedded software will cause select resistor(s) of the resistive circuit of the heating element 104 to be in electrical series with the blower vacuum motor 102. In this manner, the voltage supplied to the blower vacuum motor 102 will be controlled to a nominal 120 VAC when the input power supply is 120, 208 or 240 VAC.

(13) For a specific power supply voltage and motor design voltage, the design ratio of the resistance of the resistive circuit(s) of the heating element 104 to the dynamic resistance of the motor 102 can be calculated as follows:

(14) $\begin{array}{cc}\frac{\mathrm{RE}+\mathrm{RM}}{2\mathrm{RM}}=\frac{\mathrm{VS}}{2\mathrm{VM}}& \left(1\right)\\ \mathrm{RE}+\mathrm{RM}=\frac{\mathrm{RM}\mathrm{VS}}{\mathrm{VM}}& \left(2\right)\\ \mathrm{RE}=\frac{\mathrm{RM}\mathrm{Vs}}{\mathrm{VM}}-\mathrm{RM}& \left(3\right)\\ \mathrm{RE}=\mathrm{RM}\left(\frac{\mathrm{VS}}{\mathrm{VM}}-1\right)& \left(4\right)\end{array}$

(15) In the equations above, RE=resistance of heating element resistive circuit, RM=dynamic resistance of the blower vacuum motor, VS=power supply input voltage, and VM=voltage to be supplied to the blower vacuum motor.

(16) In practice, for an example of a 208 VAC power supply, a blower vacuum motor 102 with a dynamic resistance of 27.5 ohms designed to be supplied at 120 VAC, solving the equations results in RE=20.1 ohms where (VS/VM)1 is 0.7333. Nominal North American power supply voltages vary from 120-277 VAC. For blower vacuum motors designed for 120 VAC input, the practical ratios that can be used, the ratio of the resistances of the heating element resistive circuits to the dynamic resistance of the blower vacuum motor are shown in the table below.

(17) TABLE-US-00001 Nominal Supply Voltage (VAC) 208 240 277 Motor Design Voltage (VAC) 120 120 120 $\frac{\mathrm{resistance}\mathrm{of}\mathrm{heating}\mathrm{element}\mathrm{circuit}}{\mathrm{dynamic}\mathrm{resistance}\mathrm{of}\mathrm{motor}}$ 0.733 1.000 1.308

(18) As mentioned previously, typical blower vacuum motors used in hand dryers are sized from 500-1200 watts. Blower vacuum motors ranging in size from 500-1200 watts and having a design voltage of 120 VAC have dynamic resistances ranging from 12-29 ohms.

(19) FIG. 2 shows the schematic layout of an electrical circuit incorporating a blower vacuum motor (M), a heating element comprising two resistors (251 and 252), and three relays (201, 202 and 203) for controlling the position of the two resistive circuits of the heating element in series or parallel connection with the blower vacuum motor. A triac (T1) is used to switch the circuit on/off as desired. The schematic of FIG. 2 depicts the default contact position (open or closed) of the three relays. The relay 201 and the relay 202 have a default open (OFF) contact condition. While the relay 203 has a set of two contacts in parallela first contact 204 defaulting to open (OFF) and the second contact 205 default to closed (ON). Embedded software in the universal voltage controller 200 activates the relays as required to control the position of the two resistors (251 and 252) of the heating element in series or parallel connection with the blower vacuum motor (M). FIG. 3 indicates the activation condition (ON or OFF) of relays 201, 202 and 203 at various power supply voltages. These resistive circuits are depicted in FIGS. 4-6. Unlike semiconductor approaches that adjust the waveform, the disclosed universal voltage controller 200 maintains the same waveform. This results in an increased life of the motor.

(20) The resistive circuit depicted in FIG. 4 is suitable at a first input voltage. For example, at 120 VAC input, the relay 201 is in an ON state while the relay 202 and the relay 203 are left in an OFF state. The resistor 251 and the resistor 252 of the heating element are in series with each other and in parallel with motor M.

(21) The resistive circuit depicted in FIG. 5 is suitable at a second input voltage that is greater than the first input voltage. For example, at 208 VAC input, the relay 202 and the relay 203 are in an ON state and the relay 201 is in an OFF state. In this resistive circuit at 208 VAC, the resistor 251 is in series with the motor M. The resistor 252 is not in series with the motor M.

(22) The resistive circuit depicted in FIG. 6 is suitable at a third input voltage that is greater than both the first input voltage and the second input voltage. For example, at 240 VAC input, the relay 203 is in an ON state while the relay 201 and the relay 202 are in an OFF state. In this resistive circuit at 240 VAC, both the resistor 251 and the resistor 252 are in series with the motor M.

(23) In one practical example, the blower vacuum motor has a dynamic resistance of 27.5 ohms and the resistor 251 and the resistor 252 have design resistances of 20.15 ohms and 7.35 ohms, respectively. At 240 VAC input, the sum of resistances of the resistor 251 and the resistor 252 provides a 1:1 ratio with the dynamic resistance of the motor. At 208 VAC input, the resistor 251 is in series connection with the motor and has a resistance that develops a ratio of about 0.7 (e.g. 0.733) with the dynamic resistance of the motor.

(24) General manufacturing tolerances for a blower vacuum motor will result in a practical tolerance of +/10% for the dynamic resistance of the population of blower vacuum motors. Resistive heating elements will have a practical tolerance up to +/1 ohm resistance. It is understood that the realized ratios between the resistance of the resistive circuit(s) of the heating element and the dynamic resistance of the motor will vary according to these practical limits of tolerances, and maintain the general relationship of the design ratios and result in the desired control of the voltage supplied to the blower vacuum motor in an acceptable way.

(25) It is understood that general tolerance on the input voltage provided by utility companies is typically+6%/13% from nominal voltage. The intent of the disclosed embodiments is not to ensure a particular blower vacuum motor will always be supplied with a specific nominal voltage, but rather the voltage supplied to the blower vacuum motor will be controlled within the same range of voltages that would normally be encountered with a dedicated voltage hand dryer.

(26) It is further understood that the embodiments disclosed herein do not limit the scope of the claims below. Additional embodiments involving more than two resistive heating element circuits and having varying ratios with the dynamic resistance of the blower vacuum motor can be developed in coordination with a universal voltage controller that would control the resistive circuits in either parallel or series electrically with the control circuit of the blower vacuum motor in order to adjust and control the voltage supplied to the blower vacuum motor. Additional separate resistive circuits of a heating element can be developed to expand the range of input power supply voltages to include 120, 208, 220, 240 and 277 VAC voltages.

(27) This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.