JP2001120432A - Electric hot-water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric hot-water heater with the reduced number of parts and miniaturized devices, capable of securely driving an electric pump used in the hot-water heater, by making the structure of the electric pump different from the structure of a traditional electric pump. SOLUTION: An electric pump 2 of this hot-water heater is comprised of a rotating magnetic field generating means 8 comprised of a rotating magnetic field generating coil 6 and an impeller with a permanent magnet 5. The electric pump 2 is driven by continuously increasing the output frequency of an inverter 11 from the start of operation by a control means 12 for controlling a switching means constituting the inverter 11 for driving the rotating magnetic field generating means 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater using an electric pump having an impeller driven by receiving a rotating magnetic field generated by a coil.

[0002]

2. Description of the Related Art FIG. 14 is a block diagram of a conventional electric water heater.
Shown in As shown in FIG. 14, the conventional electric water heater includes a container 61 for accommodating a liquid, a lead-out path 62 made of a glass tube or the like for leading the liquid out of the body, a circuit board 63, and an electric pump 64. . The electric pump 64 that discharges the liquid to the outside of the body through the outlet path 62 includes a DC motor 65 and a permanent magnet 6 that is directly connected to a rotation shaft of the DC motor 65.
6, a non-magnetic waterproof plate 67, an impeller 68, and a permanent magnet 69 attached to the impeller 67. The permanent magnet 66 and the permanent magnet 69 are magnetically coupled with the waterproof plate 67 interposed therebetween. Has become. In addition, the electric pump 64 is
1 is provided with a water intake port 70 through which liquid flows in from 1 and a water outlet port 71 provided on the outer periphery of the impeller 68.

The operation of a conventional electric water heater will be described with reference to FIG. When the user performs the water discharge operation, DC power is supplied to the DC motor 65 from the circuit board 63 and the permanent magnet 66 directly connected to the rotating shaft of the DC motor 65 is rotationally driven. Since the permanent magnet 69 rotates in synchronization with the permanent magnet 66 by the above-described magnetic coupling, the impeller 68 also rotates. Thus, the liquid flowing from the container 61 through the water inlet 70 and existing around the impeller 68 causes the liquid to flow out of the container from the water outlet 71 through the outlet path 62.

[0004]

As described above, in the conventional electric water heater, a permanent magnet is directly connected to a rotating shaft of a motor such as a DC motor, and a rotating magnetic field is generated by the permanent magnet. However, the conventional electric water heater has a problem that the motor size of the electric pump is large, so that the device becomes large. In addition, this raises the problem that the bottom of the container becomes high and the center of gravity becomes high, resulting in poor stability.

An object of the present invention is to solve the above-mentioned problems of the conventional electric water heater and to provide a compact electric water heater by reducing the size of the electric pump.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a container for accommodating a liquid, an electric pump for discharging the liquid in the container, and a discharge port for the electric pump. The electric pump has an impeller having a permanent magnet, a rotating magnetic field generating means having a plurality of coils, and an inverter for driving the rotating magnetic field generating means and a plurality of parts constituting the inverter. Control means for turning on and off the switching means, wherein the control means continuously increases the output frequency of the inverter at the time of start-up, and a magnetic field generated by a coil of the rotating magnetic field generation means; Since the electromagnetic force is generated by the field of the permanent magnet of the impeller, the impeller is rotated by the rotating magnetic field generated by the rotating magnetic field generating means. Can be dynamic, it is possible to make the apparatus compact. Further, by continuously increasing the output frequency of the inverter at the time of starting, it is possible to prevent the impeller from being out of synchronization with the rotating magnetic field generated by the rotating magnetic field generating means, so that an electric water heater having stable performance can be provided. realizable.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a container for storing a liquid, an electric pump for discharging the liquid in the container, and a lead-out path connected to a discharge port of the electric pump are provided. The electric pump has an impeller having a permanent magnet, and a rotating magnetic field generating means having a plurality of coils, and controls on / off of an inverter for driving the rotating magnetic field generating means and a plurality of switching means constituting the inverter. A control unit that continuously increases the output frequency of the inverter at the time of startup. The control unit performs a rotating magnetic field generated by the rotating magnetic field generating unit, and a permanent magnet included in the impeller. Since a rotational force is generated by the electromagnetic force of the field,
The impeller can be driven to rotate, and the device can be made compact. Further, by continuously increasing the output frequency of the inverter at the time of starting, it is possible to prevent the impeller from being out of synchronization with the rotating magnetic field generated by the rotating magnetic field generating means and stopping.

According to a second aspect of the present invention, in the first aspect of the present invention, the control means sets the output frequency of the inverter to a predetermined value at the time of starting, and makes the increase rate of the output frequency of the inverter substantially constant. The impeller can be prevented from being out of synchronization with the rotating magnetic field generated by the rotating magnetic field generating means and stopped by relatively simple control. .

According to a third aspect of the present invention, in the first aspect of the present invention, the control means sets the output frequency of the inverter to a predetermined value at the time of starting, and differentiates the output frequency of the inverter twice with time. By controlling the impeller to rotate at a lower speed at the start of startup, the impeller is reliably prevented from being out of synchronization, and the target flow rate of the electric pump is controlled. Can be shortened.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the control means sets the output frequency of the inverter to a predetermined value at the time of startup, and thereafter sets the output frequency of the inverter twice in time. The differential value is increased so as to be substantially constant, and thereafter, the increase rate of the output frequency of the inverter is made substantially constant to increase to the target frequency, and the impeller is rotationally driven at a lower speed at the start of startup. Accordingly, the impeller can be prevented from being out of synchronization, and the operation stop due to the out of synchronization of the impeller can be prevented with relatively simple control during speed increase.

[0011] The invention according to claim 5 provides the above-mentioned claims 1-4.
The invention according to any one of the above, further comprising an applied voltage setting means for controlling a voltage applied to a coil included in the rotating magnetic field generating means, wherein the applied voltage setting means is configured in accordance with an output frequency of the inverter set by the control means Setting the applied voltage of the rotating magnetic field generating means,
When the output frequency of the inverter is low, the current flowing through the coil constituting the rotating magnetic field generating means can be reduced, so that the capacity of the power supply of the device can be reduced and the coil can be prevented from generating heat. . Also, noise caused by an increase in the current flowing through the coil at the time of startup can be reduced.

[0012] The invention according to claim 6 is the above-mentioned invention.
In any one of the inventions described above, the control means is configured to energize a predetermined coil for a predetermined time among the coils constituting the rotating magnetic field generating means at the time of starting, and a position of a permanent magnet constituting the impeller Can be fixed at a predetermined position, thereby preventing loss of synchronization at the time of starting the impeller and preventing the impeller from rotating in the opposite direction.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows a configuration diagram of an electric water heater in one embodiment of the present invention. In FIG. 1, container 1
Is for storing a liquid such as water. The electric pump 2 is provided on the bottom of the container 1. Derivation route 3 is
For example, it is composed of a glass tube and a coupling hose made of resin, and discharges the liquid discharged from the electric pump 2 to the outside of the container 1.

The electric pump 2 comprises an impeller 4, a permanent magnet 5 embedded in the impeller 4, a rotating magnetic field generating means 8 composed of a coil 6 and an iron core 7, and a pump case 9. The impeller 4 and the rotating magnetic field generating means 8 Is disposed so as to sandwich the pump case 9. Pump case 9 is container 1
A water inlet 9a is provided on the bottom surface of the impeller 4, and a water outlet 9b is provided on the outer periphery of the impeller 4, and the water outlet 9b is connected to a connecting hose constituting the outlet path 3. The upper surface of the pump case 9 including the water inlet 9a is detachable, and the user can open and remove the impeller 4 by opening the upper surface. Therefore, even when the scale is attached to the inside of the pump case 9, the user can remove and wash the impeller 4, which is hygienic, and can prevent the friction between the impeller 5 and the pump case 9 due to the scale, thus providing stable performance. Can be secured.

The impeller 4 has four blades and a pump case 9.
Has a tube with an inner diameter slightly larger than the outer diameter of the stainless steel rotating shaft 10 attached to the upper surface of the water outlet 9b, and by inserting the rotating shaft 10 into this tube, the impeller 4 It is arranged rotatably about the shaft 10.

In the present embodiment, the permanent magnet 5 is constituted by four poles of a ferrite magnet so that it is magnetized in the axial direction. Although not particularly shown in FIG. 1, a yoke made of an iron plate having a thickness of 1 mm is attached to the permanent magnet 5 in order to form a magnetic circuit having low magnetic resistance. This is an example, and the permanent magnet 5 is not limited to the ferrite magnet, and the number of poles is not limited to four.

The rotating magnetic field generating means 8 is configured by connecting the coil 6 to a three-phase star connection. In the present embodiment, the coil 6 is wound around the teeth of the iron core 7, whereby a magnetic circuit having a small magnetic resistance can be formed, thereby facilitating the passage of the magnetic flux of the permanent magnet 5.

Although not shown in FIG. 1, the inverter 11 has a three-phase half-wave configuration with three switching means such as transistors and MOSFETs, and supplies three-phase power to the coil 6. Then, the rotating magnetic field generating means 8 generates a rotating magnetic field. Note that inverter 1
The configuration 1 is not limited to this, and may be, for example, a three-phase full-wave configuration or a two-phase configuration.

The control means 12 includes an inverter 11 composed of a microcomputer, a logic circuit, a transistor and the like.
The switching means constituting the inverter 11 is turned on and off so that the impeller 4 rotates at a predetermined speed.

The heater 13 warms the liquid in the container 1 and allows the control means 12 to adjust the temperature based on the temperature of the liquid.

Reference numeral 14 denotes a printed wiring board. In this embodiment, the rotating magnetic field generating means 8 including the coil 6 and the iron core 7 is provided on the printed wiring board 14 together with the inverter 11 and the control means 12. This simplifies the assembly of the device and lowers the assembly cost.

However, the rotating magnetic field generating means 8 is not necessarily limited to being mounted on the same printed wiring board as the inverter 11, and for example, the rotating magnetic field generating means 8 and the inverter 11 are provided on separate printed wiring boards. Alternatively, a connector may be provided at the input terminal of the rotating magnetic field generating means 8 so as to be connected to a printed wiring board on which the inverter 11 is mounted.

Although not particularly shown in FIG. 1, in this embodiment, when the user presses the tap switch, the control means 12 detects this and drives the electric pump 2 to discharge the tap water. However, this is an example, and for example, a volume type may be used, or hot water may be discharged by detecting a user's voice.

It should be noted that, although different from the electric water heater of this embodiment, an electric water heater having a boiling water purifying function is obtained by switching a part of the lead-out path, using the same electric pump as that for discharging the hot water, to the activated carbon or the like. It is also possible to apply hot water to perform a water purification action. For example, the electric pump of the present embodiment may be used for such a configuration.

FIG. 2 is a circuit block diagram of the electric water heater of this embodiment. As shown in FIG. 2, a series circuit including a water heater 22 and a relay 23 is connected to an AC power supply 21. The AC power source 21 is a heater 24 for keeping heat.
And a diode bridge 25 to supply power to a power supply circuit 26. The power supply circuit 26 is composed of, for example, a dedicated IC or the like, and supplies a 5 V DC power supply as a power supply for a microcomputer 27 and a drive circuit 28 for driving the inverter 11 and supplies three-phase power to the rotating magnetic field generating means 8 7V DC power is supplied as a power source for this.

The rotating magnetic field generating means 8 includes coils 8a, 8b,
8c. As shown in FIG.
a to 8c are connected to a 7V output terminal of the power supply circuit, and the other terminals are connected to the switching means 1 respectively.
1a to 11c. A regenerative current diode 29 for flowing a current of the coil when the switching means 11a to 11c are turned off is provided at both ends of each of the coils 8a to 8c.
a, 29b and 29c are connected.

The inverter 11 is constituted by a three-phase half-wave by three switching means 11a, 11b and 11c. This reduces the number of switching means by half compared to a three-phase full-wave configuration using six switching means, so that the cost can be reduced. However, the inverter 11 is not particularly limited to the three-phase half-wave configuration, but may have a three-phase full-wave configuration. In the case of three-phase full-wave, the number of switching means is six and the cost is high, but the efficiency is higher than that of three-phase half-wave, so the capacity of the power supply circuit can be reduced, Can be suppressed. In this embodiment, the switching means 11a to 11c
SFET is used. The MOSFET is a voltage-driven switching means and can be driven with a small current, so that the capacity of the power supply circuit 26 and the current capacity of the drive circuit 28 can be reduced.

The microcomputer 26 outputs an on / off signal to the drive circuit 28 at a frequency corresponding to the on / off signal of the switching means 11a, 11b, 11c so that the impeller speed reaches the target speed. That is, in the present embodiment, the switching means 11a to 11c are unilaterally turned on and off by the microcomputer without providing a means for detecting the rotation speed of the impeller.
It is driven as a synchronous motor. Further, in the present embodiment, the microcomputer 26 controls the switching means 11a to 11c constituting the inverter 11, and also controls the relay 23 to be turned on / off. Thereby, the heater 22 is controlled to be on / off, and the temperature of the liquid in the container 1 is adjusted.

The drive circuit 28 includes switching means 11a to
11c is composed of three transistors corresponding to the respective transistors. The MOSFET is turned on and off by amplifying the current of the output signal of the microcomputer by the transistor. However, this is only an example. For example, if the current required when the switching means 11a to 11c is on is small, the drive circuit 28 is removed and the microcomputer 27 directly switches the switching means 11a to 11c.
You may drive c. In this case, since the cost and the mounting area of the driving circuit are not required, the cost can be reduced and the mounting area can be reduced.

As described above, by outputting the control signal of the inverter 11 from the microcomputer 27, the control signal can be integrated with the microcomputer for controlling the heater, so that the mounting area can be reduced in size and the cost can be reduced. .

FIG. 3 is a timing chart showing the on / off state of the switching means 11a to 11b when the rotation speed of the impeller 4 is N1. As shown in FIG. 3, the switching means 11a is turned on during a period from t1 to t2 by a signal from the microcomputer 27, the switching means 11b is turned on during a period from t2 to t3, and the switching means c is turned on during a period from t3 to t4. Turns on.
That is, each of the switching means 11a to 11c is turned on for one third of one cycle, and the coils 6a to 6c corresponding to the respective switching means 11a to 11c are energized.
A rotating magnetic field having output frequencies a to 11c is generated. In addition,
The microcomputer 27 is provided with a timer in advance, and the timer controls the on / off of the switching means 11a to 11c sequentially every predetermined time. However, this is only an example, and for example, an external EPROM is provided without using a timer in the microcomputer, and the switching means 1 is provided by using its logical output.
On / off control of 1a to 11c may be performed.

FIG. 4 shows the structure of the rotating magnetic field generating means 8 from above. Six teeth are provided on the iron core at equal intervals on the circumference.
1a, 41b, 41c, 41d, 41e and 41f are wound in a concentrated winding configuration. A hole is made in the center of the iron core, and the iron core is fixed to the printed wiring board by passing a screw therethrough. Note that this is an example,
An air-core configuration without the teeth may be used, or a coil may be patterned on a printed wiring board. Further, a configuration of three slots may be used instead of a configuration of six slots, and the configuration is not limited to a three-phase configuration.

FIG. 5 is a wiring diagram of the coil in the first embodiment. The black circle represents the polarity of the coil, and when a current flows from the black circle side of the coil, the coil becomes an N pole. Therefore,
For example, when a current flows from the black circle side of the coil 40a, the coil 40a and the coil 40d become N poles, and no current flows through the other coils 40b, 40c, 40e, and the coil 40f. Therefore, a rotating magnetic field can be generated by sequentially controlling the on and off of the coils 40a to 40f. With such a configuration, since a concentrated winding configuration in which the electrical angle of the width of one coil is 120 degrees, the coil end is short, the electrical resistance of the coil 17 is small, and the copper loss is reduced. Although, it has an excellent effect of reducing the number of assembling steps, it is not particularly limited to the configuration of the present embodiment.
A coil configuration having an overlap such as having a coil width of 190 degrees in electrical angle may be used.

FIG. 6 is a time chart showing the target rotation speed of the impeller 4 from the start. In this embodiment, the time chart is stored in the microcomputer, and the inverter 11 is controlled based on the time chart so that a predetermined output frequency is obtained. Here, the operation will be described with reference to FIG. When the user presses a tap switch provided on the electric kettle, the microcomputer 27 detects this and switches on / off the switching means 11a to 11c at t1 at an output frequency corresponding to the rotation speed N1 [rpm]. In this embodiment, since the permanent magnet 5 has a four-pole configuration, the frequency f1 of the switching means 11a to 11c can be obtained by the following equation.

F1 = N1 / (2 × 60) The ON period of one switching means is one third of the output period of the inverter 11 in this embodiment, as shown in FIG.

Thereafter, when the time elapses and reaches t2, the microcomputer 27 controls the switching means 11a to 11b to turn on and off at an output frequency corresponding to the rotation speed N2 [rpm]. Further, at t3, the microcomputer 27 controls on / off of the switching means 11a to 11c at an output frequency corresponding to the rotation speed N3 [rpm].

As described above, by gradually increasing the output frequency of the inverter 11 by the microcomputer 27 from the time of starting, a sharp speed fluctuation is eliminated.
Even when torque is required when the impeller 4 starts up, the period during which one coil is energized is long, so that the impeller 4 can be reliably started, and loss of synchronization can be prevented.

(Embodiment 2) FIG. 7 is a time chart of the number of revolutions of the impeller 4 constituting the electric water heater according to the second embodiment of the present invention when the number of revolutions is increased. FIG.
(A) shows a time chart of the rotation speed of the impeller 4. In this time chart, as shown in FIG. 7A, the rotation speed increases in proportion to the time to the target rotation speed Nmax. FIG. 7B shows a time chart of the acceleration of the impeller 4. As shown in FIG. 7B, the acceleration is set to a constant value a1 during the period from t1 to t2. The configuration of the electric water heater and the configuration of the circuit system are the same as those in FIGS.

The operation will be described with reference to FIG. When the user presses a tap switch provided on the electric kettle, the microcomputer 27 detects this and starts to start at t1. Then, the rotation speed N = a1 × Δt based on the elapsed time Δt from the start time t1 and the acceleration a1.
The output frequency of the inverter 11 is controlled according to the following. Thus, the rotation speed of the impeller 4 can be set by a simple linear function expression from the time of startup, so that the rotation speed can be set in a short time even if the processing performance of the microcomputer 27 is poor. Therefore, the impeller 4 can be started without any extra memory.

However, this is only an example, and if the microcomputer has a sufficient memory, the switching means 11a for the period from t1 to t2 is stored in the memory.
11c may be stored, or an external memory may be used. In this case, the microcomputer 27 only needs to detect the elapsed time Δt from the activation time t1 by the timer, so that the processing speed can be made slower than in the case where the above-described linear function is used.

(Embodiment 3) FIG. 8 is a time chart of the rotational speed of the impeller constituting the electric water heater according to a third embodiment of the present invention when the rotational speed is started. FIG.
(A) shows a time chart of the rotation speed of the impeller 4. FIG. 8B shows a time chart of the acceleration of the impeller 4. As shown in FIG. 8B, in this embodiment, the acceleration increases in proportion to the time, and the rotation speed of the impeller is set based on the acceleration. Therefore, the value obtained by differentiating twice with respect to the time of the rotation speed of the impeller 4 gradually increases. The configuration of the electric water heater and the configuration of the circuit system are the same as those in FIGS.

The operation of this embodiment will be described with reference to FIG. When the user presses a tap switch provided on the electric kettle, the microcomputer 27 detects this and starts to start at t1. Thereafter, the acceleration a is set as a = Δa × Δt based on the elapsed time Δt from the activation start time t1 and the acceleration change amount Δa. The output frequency of the inverter 11 is controlled according to the rotation speed N = a × Δt based on the acceleration a and the elapsed time Δt.

As described above, by controlling the output frequency of the inverter 11 so as to increase the rotation speed of the impeller 4 in proportion to the square of time, the output frequency of the inverter 11 is reduced to a low frequency immediately after the impeller 4 is started. By doing so, the impeller 4 can be reliably started, and thereafter, the rotational speed of the impeller 4 can be increased to the target rotational speed Nmax in a short time.

(Embodiment 4) FIG. 9 is a time chart of the rotational speed of the impeller constituting the electric water heater according to a fourth embodiment of the present invention when the rotational speed is started. FIG.
(A) shows a time chart of the rotation speed of the impeller 4. FIG. 9B shows a time chart of the acceleration of the impeller 4. As shown in FIG. 9B, in this embodiment, in this time chart, the rotation speed of the impeller 4 is set while increasing the acceleration for a predetermined time from the start, and thereafter, the acceleration is increased until the target rotation speed is reached. The rotation speed of the impeller 4 is set to be constant. The configuration of the electric water heater and the configuration of the circuit system are the same as those in FIGS.

The operation of this embodiment will be described with reference to FIG. When the user presses the tap switch provided on the electric kettle, the microcomputer 27 detects this and starts the activation at t1. Thereafter, the acceleration a is set as a = Δa × Δt based on the elapsed time Δt from the activation start time t1 and the acceleration change amount Δa. The output frequency of the inverter 11 is controlled according to the rotation speed N = a × Δt based on the acceleration a and the elapsed time Δt. Thereafter, at t2, the microcomputer 27 sets the rotation speed of the impeller 4 while keeping the acceleration constant at the set value a1. The microcomputer 27 controls the inverter 11 according to the set rotation speed.
To control the output frequency.

As described above, the output frequency of the inverter 11 is controlled so as to increase the rotation speed of the impeller 4 in proportion to the square of the time during the predetermined time from the start-up, and thereafter the impeller 4 is controlled at a constant acceleration. By increasing the rotation speed,
Immediately after the impeller 4 is started, the output frequency of the inverter 11 is set to a low frequency so that the impeller 4 is started without fail. Even when the number of revolutions of the impeller 4 is increased, a steep start-up is prevented. Impeller 4
Can be prevented from being out of synchronization. In particular, in the case of a copper machine in which the inductance of the coils 8a to 8c constituting the rotating magnetic field generating means 8 is large, torque is required to accelerate immediately after the impeller 4 is started. Although synchronization may be lost, in this embodiment, the acceleration is reduced immediately after the start-up, so that the synchronization can be prevented.

(Embodiment 5) FIG. 10 shows a circuit system configuration of an electric water heater according to a fifth embodiment of the present invention. As shown in FIG. 8, the applied voltage control means 41 has a configuration of a step-down chopper circuit using a power transistor, a coil, and a capacitor. Is supplied with a desired DC voltage.

The microcomputer 42 includes the inverter 1
In addition to the on / off control of the switching means 11a to 11c and the on / off control of the relay 22, the on / off control of the power transistor is performed. Therefore, the microcomputer 42 controls the applied voltage control means 81
And the output frequency of the inverter 11 are both controlled, so that the applied voltage according to the output frequency of the inverter 11 can be easily controlled.

This embodiment is merely an example, and the applied voltage control means 41 is not limited to this. For example, the energization ratio of the coils 8a to 8c is controlled by turning on and off the switching means 11a to 11c at a high frequency. Or a configuration of a step-up chopper circuit. When on / off control of the switching means 11a to 11c is performed at a high frequency, an operation equivalent to that of the above-described step-down chopper circuit is obtained. In this case, since there is no need to provide a step-down chopper circuit, the mounting area can be reduced. In this embodiment, a MOSFET is used, and it is possible to cope with high-frequency on / off control. In the case of the step-up chopper circuit, the rotation speed range of the impeller 4 can be widened, so that if the flow rate is the same, the shape of the blades of the impeller 4 can be reduced, and the electric pump 3 can be downsized.

FIG. 11 shows the relationship between the rotation speed of the impeller 4 and the power supply voltage supplied by the applied voltage control means 41 in this embodiment. The power supply voltage is Vmin when the rotation speed is 0 rpm.
, And thereafter the power supply voltage is controlled to increase in proportion to the rotation speed. When the rotation speed of the impeller 4 is the maximum Nmax, the power supply voltage is set to Vmax. At this time, Vmax needs to be larger than the back electromotive force generated in the rotating magnetic field generating means 8 at Nmax. In addition, a constant current is always supplied to the coils 8a to 8c by making the rate of change of the power supply voltage with respect to the number of revolutions substantially equal to the rate of change of the back electromotive force generated in the coil 8 during rotation of the impeller 4. Can be. As a result, it is possible to drive only the required torque from the start of the impeller 4 to the target number of revolutions, so that the current flowing through the coil at low speed can be prevented from becoming an issue, and the heat generation of the coil and the failure of the switching means can be prevented. Noise reduction can be realized.

(Embodiment 6) FIG. 12 shows an electric pump 1 constituting an electric water heater according to a sixth embodiment of the present invention.
4 is a flowchart at the time of startup. Other configurations are the same as those in FIGS.

Hereinafter, the operation of the electric kettle of this embodiment will be described with reference to FIG. When the user turns on the hot water switch in step 51, the microcomputer 27 detects this and turns on the switching means 11a for a predetermined period T1 in step 52. Thereafter, in step 53, the output frequency of the inverter 11 is controlled according to the time chart shown in FIG. 7 to drive the inverter 11 to the target rotational speed Nmax.

FIG. 13 is a timing chart showing the on / off state of the switching means 11a to 11c immediately after the start of the electric pump 14. (A) is the switching means 11
The on / off state of a is shown. (B) shows the on / off state of the switching means 11b. (C) shows the on / off state of the switching means 11c.

The operation will be described with reference to FIGS. When the user presses the tap switch in step 51 of FIG. 12, the microcomputer 27 detects this and presses the tap switch.
The switching means 11a is turned on at t1 of the
a is energized. After that, when a predetermined period T1 has elapsed, FIG.
From t2 of 3, the switching means 11a to 11b are sequentially turned on and off based on the time chart in FIG.
Thereby, a rotating magnetic field is generated in the rotating magnetic field generating means 8, and
The impeller 4 is driven to rotate by acting on the field of the permanent magnet.

As described above, by turning on the predetermined switching means for a certain period when the electric pump is started, a predetermined coil is energized, and the permanent magnet of the impeller 4 is attracted by the magnetic field generated by this coil. Thus, the relative position between the permanent magnet and the rotating magnetic field generating means can be reliably fixed. Therefore, since the position of the permanent magnet is known, the coil to be energized first can be determined so that the rotation direction is not reversed, so that the electric pump can be started up reliably.

In the first to sixth embodiments, the electric pump having a so-called axial gap configuration in which the field direction of the permanent magnet is set to the direction of the rotation axis of the impeller 4 has been described. Without limiting, for example, while setting the field direction of the permanent magnet embedded in the impeller to be perpendicular to the rotation axis of the impeller,
Place the coil 1 in a horizontal position with respect to the coil.
The outer rotor 7 may be configured to rotate on the outside. In this case, the attractive force in the axial direction can be prevented by the permanent magnet provided on the impeller and the iron core constituting the rotating magnetic field generating means, so that the friction between the tip of the impeller and the pump case can be reduced, and the durability of the electric pump can be reduced. Can be improved.

[0057]

As described above, according to the first aspect of the present invention, the rotating force is generated by the rotating magnetic field generated by the rotating magnetic field generating means and the electromagnetic force generated by the field of the permanent magnet of the impeller. Therefore, the impeller can be driven to rotate, and the device can be made compact. Further, by continuously increasing the output frequency of the inverter at the time of starting, it is possible to prevent the impeller from being out of synchronization with the rotating magnetic field generated by the rotating magnetic field generating means and stopping.

According to the second aspect of the present invention, with a relatively simple control, the impeller can be prevented from being out of synchronization with the rotating magnetic field generated by the rotating magnetic field generating means and stopped. .

According to the third aspect of the invention, by rotating the impeller at a lower speed at the start of startup, the impeller is reliably prevented from being out of synchronization, and the time required to reach the target flow rate of the electric pump is shortened. can do.

According to the fourth aspect of the present invention, the impeller is rotated at a lower speed at the start of startup to prevent the impeller from being out of synchronization, and while the speed is increasing, the impeller is out of synchronization by relatively simple control. Can be prevented from being stopped.

According to the fifth aspect of the present invention, when the output frequency of the inverter is low, the current flowing through the coil constituting the rotating magnetic field generating means can be reduced, and the capacity of the power supply of the device can be reduced. In addition, heat generation of the coil can be prevented. Also, noise caused by an increase in the current flowing through the coil at the time of startup can be reduced.

According to the sixth aspect of the present invention, the position of the permanent magnet constituting the impeller can be fixed at a predetermined position, so that the synchronization at the time of starting the impeller is prevented, and the impeller is moved in the reverse direction. Rotation can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electric water heater showing one embodiment of the present invention.

FIG. 2 is a circuit system configuration diagram of the electric water heater.

FIG. 3 is a timing chart of the inverter of the electric water heater.

FIG. 4 is a configuration diagram of a rotating magnetic field generating means of the electric water heater.

FIG. 5 is a connection diagram of a coil constituting a rotating magnetic field generating means of the electric water heater.

FIG. 6 is a time chart for starting an electric pump in an electric water heater according to an embodiment of the present invention.

FIG. 7 is a time chart for starting an electric pump in an electric water heater according to an embodiment of the present invention.

FIG. 8 is a time chart for starting an electric pump in an electric water heater according to an embodiment of the present invention.

FIG. 9 is a time chart for starting an electric pump in an electric water heater according to an embodiment of the invention as set forth in claim 4.

FIG. 10 is a circuit system configuration diagram of an electric water heater according to an embodiment of the invention described in claim 5.

FIG. 11 is a graph showing the relationship between the output voltage of the applied voltage control means constituting the electric water heater and the rotation speed of the impeller.

FIG. 12 is a flowchart for starting an electric pump in an electric water heater according to an embodiment of the present invention.

FIG. 13 is a timing chart of an inverter for driving an electric pump in the electric water heater.

FIG. 14 is a configuration diagram of a conventional electric water heater.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Electric pump 3 Outgoing route 4 Impeller 5 Permanent magnet 6 Coil 7 Iron core 8 Rotating magnetic field generating means 9 Pump case 9a Water inlet 9b Water outlet 10 Rotating shaft 11 Inverter 12 Control means 13 Heater 14 Printed circuit board

 ──────────────────────────────────────────────────の Continued on the front page (72) Tomoya Toto, Inventor 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 4B055 AA34 BA10 BA35 CA62 CD61 GA14 GB12 GC31 GC40 GD01 GD04

Claims (6)

[Claims] 1. An impeller having a container for storing a liquid, an electric pump for discharging the liquid in the container, and an outlet connected to a discharge port of the electric pump, wherein the electric pump has a permanent magnet, A rotating magnetic field generating means having a plurality of coils, and an inverter for driving the rotating magnetic field generating means and a control means for controlling on / off of a plurality of switching means constituting the inverter; An electric water heater that continuously increases the output frequency of the inverter. 2. The electric water heater according to claim 1, wherein the control means sets the output frequency of the inverter to a predetermined value at the time of startup, and increases the output frequency of the inverter to a target frequency while keeping the increase speed substantially constant. 3. The electric device according to claim 1, wherein the control means sets the output frequency of the inverter to a predetermined value at the time of start-up, and controls the output frequency of the inverter so that a value obtained by differentiating the output frequency twice with time becomes substantially constant. Water heater. 4. The control means sets the output frequency of the inverter to a predetermined value at the time of start-up, and thereafter increases the output frequency of the inverter twice so as to be substantially constant. 2. The electric water heater according to claim 1, wherein the rate of increase of the output frequency of the inverter is increased to a target frequency while being substantially constant. 5. Apparatus for controlling a voltage applied to a coil included in a rotating magnetic field generating means, the applied voltage controlling means comprising: an applying voltage controlling means for controlling the rotating magnetic field generating means in accordance with an output frequency of an inverter set by the controlling means. The electric water heater according to claim 1, wherein an applied voltage is set. 6. The electric water heater according to claim 1, wherein the control means energizes a predetermined coil of the coils constituting the rotating magnetic field generating means for a predetermined time at the time of startup.