Washing machine

A washing machine includes a washing machine housing having electrical conducting properties and having an earth connection portion, a leaked water tub having electrical insulating properties and installed in a bottom part of the washing machine housing for accumulating leaked water, an electrode for detecting presence or absence of the leaked water in the leaked water tub, a leaked water detection circuit connected to the electrode, the leaked water detection circuit having an electrical insulating function, a retaining member having electrical insulating properties and retaining the electrode, and an attachment member having electrical conducting properties and attaching the electrode to the washing machine housing via the retaining member. The attachment member is electrically connected to the washing machine housing. In the leaked water tub, a lowest end of the attachment member is positioned on the lower side of a lowest end of the electrode. Thereby, a safe and inexpensive washing machine is realized.

This application is a 371 application of PCT/JP2012/001203 having an international filing date of Feb. 22, 2012, which claims priority to JP2011-036737 filed Feb. 23, 2011, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a washing machine having high safety.

BACKGROUND ART

For example, a washing machine described in Patent Document 1 has a dirt sensor such as a conductivity sensor for detecting a state of a washing liquid in a water tank, and executes control of a washing step based on a detection result of the state of the washing liquid such as dirt.

FIG. 4is a vertically sectional view of the washing machine described in Patent Document 1.

As shown inFIG. 4, a transparency detection portion63for detecting a transparency of the washing liquid is provided in a drainage port of a water tank62accommodating a washing tank61in which an agitation blade67is arranged on a bottom. The transparency of the washing liquid detected by the transparency detection portion63is converted into a voltage signal by a first control portion63aconfigured by an input unit, an output unit, and an arithmetic control unit. The first control portion63adrives a motor66for driving the agitation blade67via a motor drive portion65based on this voltage signal.

Between the washing tank61and the water tank62, a conductivity detection portion64for detecting conductivity of the washing liquid is provided. Based on the conductivity of the washing liquid detected by the conductivity detection portion64, a second control portion64aformed by an input unit, an output unit, and an arithmetic control unit determines a type of detergent. The second control portion64adrives the motor66via the motor drive portion65based on the determined type of detergent.

The second control portion64aextends a washing time in correspondence with the determined type of detergent.Patent Document 1: Japanese Unexamined Patent Publication No. 63-154196

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

As a detection portion (sensor) for detecting the state of the washing liquid like the transparency detection portion and the conductivity detection portion provided in the washing machine described in Patent Document 1, there is a detection portion (sensor) for applying an electric current to the washing liquid at the time of detection. For example, in order to detect leaked water due to deterioration of a seal member for sealing a joint of the water tank and breakage of a water supply passage or a drainage passage, an electrode of a leaked water detection portion for detecting the leaked water is provided in a bottom part of the washing machine. In a case where the leaked water overflows to an exterior of the washing machine, there is a possibility that a user contacts the leaked water electrically connected to the electrode so as to get an electric shock. As a countermeasure, it is thought that reinforced insulation is provided between the electrode of the leaked water detection portion and the user. However, the reinforced insulation requires high cost.

Thus, an object of the present invention is to provide a safe and inexpensive washing machine not requiring expensive reinforced insulation.

Means for Solving the Problems

In order to achieve the above object, the present invention is formed as follows.

According to an aspect of the invention, there is provided a washing machine, comprising: a washing machine housing having electrical conducting properties and having an earth connection portion; a leaked water tub having electrical insulating properties and installed in a bottom part of the washing machine housing for accumulating leaked water; an electrode for detecting presence or absence of the leaked water in the leaked water tub; a leaked water detection circuit connected to the electrode, the leaked water detection circuit having an electrical insulating function; a retaining member having electrical insulating properties and retaining the electrode; and an attachment member having electrical conducting properties and attaching the electrode to the washing machine housing via the retaining member, wherein the attachment member is electrically connected to the washing machine housing, and in the leaked water tub, a lowest end of the attachment member is positioned on a lower side of a lowest end of the electrode.

Effects of the Invention

According to the present invention, the safe and inexpensive washing machine can be realized by a simple configuration without requiring expensive reinforced insulation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is a washing machine including a washing machine housing having electrical conducting properties and having an earth connection portion, a leaked water tub having electrical insulating properties and installed in a bottom part of the washing machine housing for accumulating leaked water, an electrode for detecting presence or absence of the leaked water in the leaked water tub, a leaked water detection circuit connected to the electrode, the leaked water detection circuit having an electrical insulating function, a retaining member having electrical insulating properties and retaining the electrode, and an attachment member having electrical conducting properties and attaching the electrode to the washing machine housing via the retaining member, wherein the attachment member is electrically connected to the washing machine housing, and in the leaked water tub, a lowest end of the attachment member is positioned on a lower side of a lowest end of the electrode.

According to the present invention, the leaked water in the leaked water tub is brought into contact with the lowest end of the attachment member before being brought into contact with the electrode. The attachment member is electrically connected to the washing machine housing grounded by the earth connection portion. Thereby, even when contacting with the leaked water, a user does not get an electric shock. As a result, a safe and inexpensive washing machine is realized.

The leaked water detection circuit and the electrode may be electrically separated by a transformer. Thereby, safety of the washing machine is further improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that although the present invention will be described taking a drum washing machine as an example, the present invention is not limited to the drum washing machine. The present invention is applicable to an upright type washing machine.

FIG. 1is a vertically sectional view of the washing machine in the embodiment of the present invention.

As shown inFIG. 1, a cylindrical rotary drum1with a bottom has a plurality of water passage holes2in an outer peripheral part. The rotary drum1is rotatably arranged in a water tank3so that a rotation center line thereof is inclined downward from a front surface of the washing machine toward a back surface. A rotation shaft (rotation center axis)4extending in the substantially inclining direction is provided in a rotation center part of the rotary drum1. A motor5attached to a back part of the water tank3is coupled to this rotation shaft4. The rotary drum1is driven and rotated in the forward direction or in the reverse direction by the motor5. Several protuberances6are provided on an inner wall surface of the rotary drum1.

A lid body7openably and closably covers an opening portion formed on an upward inclined surface of a washing machine housing9which is positioned on the front surface side of the water tank3. By opening this lid body7, a laundry can be brought into the rotary drum1via a laundry outlet/inlet8.

The water tank3is oscillatably elastically supported on the washing machine housing9via an anti-vibration damper (not shown). In order to drain a washing liquid, one end of a drainage member10is connected to a lower part of the water tank3, and the other end of the drainage member10is connected to a drainage valve11. A water supply valve12supplies water into the water tank3via a water supply passage13.

A leaked water tub15having electrical insulating properties, for receiving and accumulating the washing liquid (leaked water), which leaked due to breakage of the water tank3, the water supply passage13, or the drainage valve11, is provided in a bottom part of the washing machine housing9. The leaked water tub15is manufactured from electrical insulating resin for example. In the leaked water tub15, an electrode (electrode sensor)54for detecting presence or absence of the leaked water in the leaked water tub15is arranged.

The washing machine housing9is provided with a back surface having electrical conducting properties and having an earth connection portion58for grounding. For example, the back surface of the washing machine housing9is manufactured from metal. A base frame70of the washing machine housing9also has electrical conducting properties and is manufactured from metal for example. The back surface of the washing machine housing9and the base frame70are in contact with each other (that is, electrically connected to each other).

The electrode54is retained by a retaining member71having electrical insulating properties and manufactured from resin. The electrode54is retained by the retaining member71in a state that a front end is directed downward, that is, the front end is directed toward a bottom of the leaked water tub15.

The insulating retaining member71is attached to an attachment member37, which having electrical conducting properties and manufactured from metal, by using a screw. The conductive attachment member37is attached (that is, electrically connected) to the washing machine housing9(base frame70). The leaked water accumulated in the leaked water tub15is detected by contact with the electrode54.

The conductive attachment member37extends downward in the leaked water tub15, and a lowest end thereof is positioned on the lower side of a front end (lowest end) of the electrode54. Therefore, before the leaked water is brought into contact with the front end of the electrode54, the leaked water is brought into contact with the lowest end of the attachment member37. The attachment member37is electrically connected to the back surface of the washing machine housing9grounded via the earth connection portion58. Thus, even when contacting with the leaked water overflowing from the leaked water tub15(that is, the leaked water electrically connected to the electrode54), a user does not get an electric shock. As a result, safety of the user is ensured.

It should be noted that the rotary drum1of the present embodiment is arranged so that the rotation center line thereof is inclined downward from the front surface of the washing machine toward the back surface. Instead of this, the rotary drum may be arranged in the washing machine so that the rotation center line direction of the rotary drum1matches with the substantially horizontal direction or the substantially vertical direction.

FIG. 2is a circuit diagram of the washing machine in the embodiment of the present invention.

As shown inFIG. 2, the washing machine has a rectifier29for converting AC power from an AC power source28into DC power, and a smoothing circuit configured by a choke coil30and a smoothing capacitor31for smoothing the DC power. A control portion16of the washing machine drives the motor5via an inverter23with the smoothed DC power and controls actions of the water supply valve12, the drainage valve11, and the like. Thereby, the control portion16controls a washing step, a rinsing step, and a water removal step.

The control portion16displays information inputted by the user via an input setting portion17for setting an operation course and the like on a display portion18so as to notify the user. When an operation is started by the user via the input setting portion17, the control portion16controls the actions of the drainage valve11, the water supply valve12, and the like via a load drive portion20based on a signal from a water level detection portion19for detecting a water level of the washing liquid in the water tub3, a signal from a leaked water detection portion27for detecting the leaked water via the electrode54, or the like, so as to execute a washing operation. It should be noted that in a case where an abnormality is detected, the control portion16notifies of the abnormality.

Further, the control portion16controls the inverter23via a drive circuit22based on a detection result of position detection portions21for detecting a position of a rotor of the motor5, so as to control rotation of the motor5.

The motor5is a DC brushless motor formed by a stator having three phase windings, and the rotor in which two polar permanent magnets are arranged on a ring although not shown. A first winding5a, a second winding5b, and a third winding5cforming the three phase windings of the stator are wound around an iron core provided with a slot.

The inverter23is formed by a plurality of switching elements including parallel circuits of power transistors (IGBT) and reverse conducting diodes. Specifically, the inverter23has a series circuit of a first switching element23aand a second switching element23b, a series circuit of a third switching element23cand a fourth switching element23d, and a series circuit of a fifth switching element23eand a sixth switching element23f. The three series circuits are connected in parallel.

Both ends of the series circuit of the switching elements are input terminals connected to a DC power source, and a connection point of the two switching elements forming the series circuit of the switching elements is an output terminal. The output terminals are connected to a U terminal, a V terminal, and a W terminal of the three phase windings. By selectively turning on/off the two switching elements forming the series circuit of the switching elements, the U terminal, the V terminal, and the W terminal are selectively brought into a positive voltage application state, a zero voltage application state, and an open voltage application state.

Turning on/off of the switching elements is controlled by the control portion16based on the detection result of the three position detection portions21a,21b,21cincluding Hall elements for detecting the position of the rotor. The position detection portions21a,21b,21care arranged in the stator at a 120-degree interval of an electric angle with facing the permanent magnets of the rotor.

While the rotor makes one rotation, the three position detection portions21a,21b,21coutput pulses at a 120-degree internal of an electrical angle. The control portion16detects a timing when a state of an output signal from any of the three position detection portions21a,21b,21cis changed. Based on the signal of the position detection portion21a,21b,21cwhose state is changed, the control portion16switches on/off the switching elements23ato23fand selectively brings the U terminal, the V terminal, and the W terminal into the positive voltage application state, the zero voltage application state, and the open voltage application state, so as to selectively apply electric power to the first winding5a,the second winding5b, and the third winding5cof the stator. The rotor is rotated by a magnetic field generated by the winding to which the electric power is applied.

The switching elements23a,23c,23eare respectively pulse-width modulation (PWM) controlled, for example, controlled by a PWM signal of repetition frequency of 10 kHz. The control portion16controls a DUTY ratio of the PWM signal so as to control the rotation number of the rotor. Every time when the state of the output signal from any of the three position detection portions21a,21b,21cis changed, the control portion16calculates a cycle of the output signal, and calculates the rotation number of the rotor from the calculated cycle. The control portion16PWM controls the switching elements23a,23c,23eso that the calculated rotation number of the rotor becomes the set rotation number.

A torque detection portion24is formed by a resistance25connected to the input terminals on one side of the inverter23, and an electric current detection circuit26connected to this resistance25. The torque detection portion24detects an input current of the inverter23, coverts the detected input current into a voltage signal, and outputs the voltage signal to the control portion16. The control portion16A/D converts the voltage signal inputted from the torque detection portion24, and computes the digital signal after conversion. In a case where the motor5is a DC brushless motor, torque of the motor5is substantially proportional to the input current of the inverter23. Therefore, by detecting an input current value of the inverter23by the electric current detection circuit26connected to the resistance25, the torque of the motor5can be detected.

FIG. 3shows a leaked water detection circuit60in the leaked water detection portion27.

As shown inFIG. 3, the leaked water detection circuit60is electrically separated from the electrode54by a transformer57so as to have a basic insulation function. By this transformer57, an electric shock of the user due to the leaked water electrically connected to the electrode54is further prevented. In the leaked water detection circuit60, the transformer57, an inverter56, and capacitors32,33form a parallel resonance circuit.

A diode34, a capacitor35, and a resistance36smooth a resonance output of the parallel resonance circuit. Based on a resistance value between both ends of the electrode54, the presence or the absence of the leaked water in the leaked water tub15is detected.

As described above, according to the present embodiment, the washing machine can prevent the electric shock of the user due to the leaked water by inexpensive basic insulation without providing expensive reinforced insulation to the leaked water detection portion27(leaked water detection circuit60). As a result, a safe and inexpensive washing machine can be realized.

It should be noted that reinforced insulation or basic insulation is generally defined by the Electrical Appliance and Material Safety Law and IEC (International Electrotechnical Commission).

The entire disclosure of Japanese Patent Application No. 2011-036737 filed on Feb. 23, 2011 including specification, drawings, and claims is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

As described above, the present invention can realize an inexpensive and safe washing machine by basic insulation without requiring reinforced insulation. Therefore, the present invention can be applied to various types of washing machines.