Tilted drum-type washing machine with pulsator and method for controlling the same

The drum type washing machine includes a tub of plastic having a wall portion for holding washing water and securing a driving unit thereto, and a front side sloped upward at a predetermined angle from ground, a drum rotatably mounted in the tub, a hollow drum shaft passed through the tub, and connected to the drum inside of the tub for transmission of driving power from a motor to the drum, at least one bearing for supporting the hollow drum shaft, a stator fixedly secured to the rear wall portion of the tub, a rotor connected to a rear end of the drum shaft to constitute a motor together with the stator, a pulsator rotatably mounted in the drum, a pulsator shaft mounted to pass through the hollow of the drum shaft, having a fore end connected to the pulsator, and pulsator control means for braking/releasing rotation the pulsator.

This application claims priority to International Application No. PCT/KR2005/001909 filed on Jun. 20, 2005, as well as Korean Applications P 2004-46105 filed on Jun. 21, 2004, P 2004-46106 filed on Jun. 21, 2004, P 2004-46107 filed on Jun. 21, 2004, and P 2004-46142 filed Jun. 21, 2004, all of which are incorporated by reference, as if fully set forth herein.

TECHNICAL FIELD

The present invention relates to drum type washing machines, and more particularly, to a drum type washing machine of a new structure, in which a structure of the drum type washing machine is improved, to make introduction and take out of laundry easy, and to enhance a washing performance.

BACKGROUND ART

In general, the washing machine is a home appliance for removing dirt from laundry by chemical decomposition of detergent and mechanical impact of water circulation.

Of the washing machines, since the drum type washing machine permits, not only to reduce a total height compared to a pulsator type washing machine having an upstanding cylindrical inner tub rotatably mounted therein, but also to increase a washing capacity more compared to a same size of the pulsator type washing machine, and cause no problem of entangling of laundry while reducing washing water consumption, it is a trend that demands for the drum type washing machine increases more and more.

A related art drum type washing machine will be described in detail, with reference to the attached drawings.

FIG. 1illustrates a section of a related art drum type washing machine, provided with a tub2suspended with dampers and springs in a cabinet1, a cylindrical drum3rotatably mounted in the tub2, and a driving unit coupled to the drum3with a shaft.

The driving unit provided to a rear of the tub2with a rotor4and a stator5, wherein a rotor shaft6rotatable with the drum3is directly coupled to the rotor4for transmission of a driving power from the rotor to the drum3directly without a pulley or a belt.

On a front of the cabinet1, there is a door10on an opening of the drum, and between the door10and the drum3, there is a gasket20for sealing.

Upon application of power to the drum type washing machine, the rotor4rotates by electromagnetic interaction with the stator5, to transmit rotation force thereof to the drum3through the rotor shaft6.

In this instance, the washing is made by an impact of drop of the laundry lifted by a lifter3aas the drum3rotates.

However, the related art drum type washing machine has a problem in that introduction/taking out laundry into/from drum3is not convenient since the user is required to squat or bend as the door10is at a center of the front of the cabinet1, and the drum3is mounted horizontally.

Moreover, the washing made only relying on rotation of the drum can not provide a good washing performance.

That is, since the related art drum type washing machine makes washing by a simple method of lifting and dropping laundry with the lifters, the related art drum type washing machine has a limit in enhancing a washing performance.

Meanwhile, even a related art drum type washing and drying machine also has the same problem.

DISCLOSURE

Technical Problem

An object of the present invention is to provide a tilted drum type washing machine of a new structure, which can make introduction and take out of laundry easy, reduce water consumption, and enhance washing performance, and effect, and a method for controlling the same.

TECHNICAL SOLUTION

The object of the present invention can be achieved by providing The drum type washing machine includes a tub of plastic having a wall portion for holding washing water and securing a driving unit thereto, and a front side sloped upward at a predetermined angle from ground, a drum rotatably mounted in the tub, a hollow drum shaft passed through the tub, and connected to the drum inside of the tub for transmission of driving power from a motor to the drum, at least one bearing for supporting the hollow drum shaft, a stator fixedly secured to the rear wall portion of the tub, a rotor connected to a rear end of the drum shaft to constitute a motor together with the stator, a pulsator rotatably mounted in the drum, a pulsator shaft mounted to pass through the hollow of the drum shaft, having a fore end connected to the pulsator, and pulsator control means for braking/releasing rotation of the rotation of the pulsator.

In another aspect of the present invention, a method for controlling a tilted drum type washing machine, in which rotation of a pulsator in a drum is controlled by braking/releasing a pulsator rotation control pulley, the tilted drum type washing machine comprising a tub of plastic having a wall portion for holding washing water and securing a driving unit thereto, and a front side sloped upward at a predetermined angle from ground, a drum rotatably mounted in the tub, lifters on an inside circumferential surface of the drum, a hollow drum shaft passed through the tub, and connected to the drum inside of the tub for transmission of driving power from a motor to the drum, at least one bearing for supporting the hollow drum shaft, a sleeve shaped bearing housing for supporting the bearing, a stator fixedly secured to the rear wall portion of the tub, a rotor bushing of an insulating material secured to a rear end of the drum shaft, a rotor secured to the rotor bushing for transmission of driving force to the drum shaft through the rotor bushing, a rotor secured to a rear end of the drum shaft to constitute a BLDC motor together with the stator, a pulsator rotatably mounted on an inside of the drum, having curved shape of washing fins on a main surface thereof, a pulsator shaft mounted to pass through the hollow of the drum shaft, having a fore end connected to the pulsator, a pulley positioned in rear of the rotor, and coupled to a rear end of the pulsator shaft, for controlling rotation of the pulsator, and a braking device including a solenoid secured to the tub, a plunger moving back and forth in the solenoid, so that the plunger brakes or releases the pulley depending on electric turn on/off of the solenoid, for braking/releasing rotation of the pulsator, the method comprising the steps of performing washing in a state the pulsator is held, and performing washing in a state the pulsator is released to rotate freely.

In the meantime, in another aspect of the present invention, a drum type washing machine includes a tub of plastic having a wall portion for holding washing water and securing a driving unit thereto, a front side sloped upward at a predetermined angle from ground, a hot air inlet in an upper side of a rear wall, and a hot air outlet in a lower side of a front, a drum rotatably mounted in the tub, having hot air pass through holes in a rear wall, a hollow drum shaft passed through the tub, and connected to the drum inside of the tub for transmission of driving power from a motor to the drum, at least one bearing for supporting the hollow drum shaft, a sleeve shaped bearing housing for supporting the bearing, a stator fixedly secured to the rear wall portion of the tub, a rotor connected to a rear end of the drum shaft to constitute a motor together with the stator, a pulsator rotatably mounted in the drum, having hot air supply holes in a main surface thereof, a pulsator shaft mounted to pass through the hollow of the drum shaft, having a fore end connected to the pulsator, pulsator control means for braking/releasing rotation of the rotation of the pulsator, and hot air supply means for supplying hot air into the drum to dry the laundry in the drum.

ADVANTAGEOUS EFFECTS

As has been described, the drum type washing machine in accordance with first, or second preferred embodiment of the present invention can improves product reliability of the user as the tilted tub enables easy introduction and taking out of the laundry, and to reduce consumption of water in washing.

Particularly, the rotation of the drum in a tilted state, and the provision of pulsator inside of the drum vary movement of the laundry and water circulation within the drum, which improves a washing performance.

That is, the positional change of the laundry caused by the sloped surface of the washing fins and the slope of the main surface of the pulsator makes back and forth movements of the laundry more active than the related art in which the laundry is merely lifted up by the lifters and dropped, to vary the movements of the laundry, and the water circulation, which improves a washing performance.

Moreover, the application of a new drying system in which hot air is center blown along an axis of the drum permits the air to penetrate deep into an inside of the drum, to improve a drying efficiency, and a drying performance.

The connection of the drying duct to the tub, making the gasket arranged in an exact symmetry permits uniform absorption of vibration of the tub, and, different from the related art, resolves the problem of unnecessary heating of the door.

The drying duct also serving as a balance weight improves a balance sustaining capability of the tub.

In the meantime, along with the improvement of the washing and drying performance, the provision of auto-balancers to a front and a rear of the drum for maintaining balance of the drum by means of fluid in addition to the balance weights mounted on the tub permits effective reduction of system vibration caused by en eccentric load in the drum during spinning.

BEST MODE

Preferred embodiments of the present invention will be described in more detail with reference toFIGS. 2 to 12.

A first preferred embodiment of the present invention will be described with reference toFIGS. 2 to 8.

FIG. 2illustrates a longitudinal section of a drum type washing machine in accordance with a first preferred embodiment of the present invention schematically,FIG. 3illustrates a key part section, an enlarged view of the “A” part inFIG. 2, showing a pulsator in stationary, andFIG. 4illustrates a key part section, an enlarged view of the “A” part inFIG. 2, showing a pulsator in rotation.

FIG. 5illustrates a perspective view of the pulsator inFIG. 2,FIG. 6illustrates a perspective view showing a pulsator rotation control pulley of the present invention as an example,FIG. 7illustrates a perspective view of a back side ofFIG. 6, andFIG. 8illustrates a perspective view of a rotor bushing inFIG. 3or4.

Referring toFIGS. 2 to 8, the drum type washing machine includes a tub2of plastic having a wall portion for holding washing water and securing a driving unit thereto, and a front side sloped upward at a predetermined angle from ground, a drum3rotatably mounted in the tub2, a hollow drum shaft6passed through the tub2, and connected to the drum3inside of the tub2for transmission of driving power from a motor to the drum, bearings113a, and113bfor supporting the hollow drum shaft6, a bearing housing113of a sleeve shape for holding the bearings113aand113b, a stator5fixedly secured to the rear wall portion of the tub2, a rotor4connected to a rear end of the drum shaft6to constitute a BLDC motor together with the stator5, a pulsator7rotatably mounted in the drum3, a pulsator shaft8mounted to pass through the hollow of the drum shaft6, having a fore end connected to the pulsator7, and pulsator control means for braking/releasing rotation of the rotation of the pulsator.

The pulsator control means includes a pulley15in rear of the rotor4connected to a rear end of the pulsator shaft8, for controlling rotation of the pulsator, and a braking device11for controlling rotation of the pulsator7in the drum3by braking/releasing the pulley15.

At a center of a rear side of the tub2, there is the bearing housing113insert molded thereto as one unit therewith, having the front and rear bearings113a, and113bpress fit therein for supporting the drum shaft6at a rear side of the drum3.

The stator5is fastened to the rear wall of the tub2with fastening members, such as bolts.

In the meantime, the pulsator shaft8is supported on oiless bearings800a, and800bmounted on a front and a rear of the shaft8, respectively.

Though it is preferable that the bearings113aand113b, supporting the hollow drum shaft6, are mounted on a front side and a rear side of the shaft respectively for secure supporting of the shaft, there is no limit in a number of bearings.

In this instance, mounting the bearings113aand113bfar from each other on the front side and rear side of the drum shaft6is favorable for secure supporting of the shaft.

It is favorable that, of the bearings113aand113bsupporting the hollow drum shaft6, the front side bearing113aof the drum shaft6has a diameter grater than a diameter of the rear side bearing113bfor minimizing vibration of the drum3during spinning, and making strength higher.

In front of the front side bearing113aof the drum shaft6, there is a water seal12for preventing water leakage, having a spring120atherein for pressing the water seal12toward an outside circumferential surface of the drum shaft6.

An outside of the water seal12is supported either on the bearing housing113, or a shape of the rear wall of the tub as shown inFIGS. 3 and 4.

The braking device11includes a solenoid11asecured to the tub2, and a plunger11bmoving back and forth in the solenoid11a, so that the plunger11bbrakes or releases the pulley15depending on electric turn on/off of the solenoid11a, for braking/releasing rotation of the pulsator7.

It is preferable that an elastic member, such as a compression spring11c, is mounted in the solenoid11a.

This is for the plunger11bto be lead to a position of the holding recess150ain the pulley15automatically after a moment even if the plunger11bmoves backward by elasticity, taking a chance the pulley15coupled to the pulsator7rotates owing to engagement based on friction of laundry in the drum following rotation of the drum3, even if the holding recess150ain the pulley15is not aligned with the plunger11bat the time the plunger11bmoves forward for braking the pulsator7, but comes into contact with an outside surface of a sidewall15bof the pulley11bspaced away from the holding recess150a.

Different from above example in which the solenoid11ais secured to the tub2, the braking device of the solenoid11amay be secured, not to the tub2, but to other place, such as the cabinet1, with the compression spring11cand the plunger11bprovided therein, so that the back and forth movement of the plunger11bfollowing electric turn on/off of the solenoid11abrakes/releases the pulley15, thereby controlling braking/releasing rotation of the pulsator7.

In the meantime, between the drum shaft6and the rotor4, there is a rotor bushing13of plastic for coupling to the drum shaft6and the rotor frame4ain a state the rotor bushing13is positioned in rear, or front of a rotor frame4a.

The rotor bushing13includes an engagement portion13afor placing in, and engagement with the drum shaft6at a center thereof, and a coupling portion13bextended in a radial direction from a circumference of the engagement portion13afor coupling with the rotor frame4a.

It is preferable that the coupling portion13bof the rotor bushing13includes a plurality of positioning projections formed as one body therewith and projected toward the rotor frame4a, or a plurality of fastening holes131bfor fastening to the rotor frame4awith bolts.

It is preferable that reinforcing ribs13care provided further at least one of the engagement portion13aand the coupling portion13bof the rotor busing13for reinforcement.

There are serration formed on an outside circumferential surface of a rear end portion of the drum shaft6, and on an inside circumferential surface of a center of the engagement portion13aof the rotor bushing opposite thereto, for engagement with each other.

In the meantime, on an outer side of the rear wall of the drum3, there is a spider16secured thereto for supporting the rear wall300of the drum and reinforcing the strength, and at a front end portion of the drum shaft6, there is a flange600in close contact with the spider16, for fastening the drum rear wall300, the spider16, and the flange600of the drum shaft6with fastening members17passed therethrough, together.

The pulsator shaft8has serrations on opposite end portion for engagement with the pulsator7and the pulley15, preferably each with an involute profile surface.

The pulley15includes a rear wall portion15acovering the rear wall of the rotor frame4a, a sidewall portion15bfor covering a sidewall of the rotor frame4aof steel fabricated by pressing, an engagement portion15cat a center of the rear wall portion15afor engagement with the pulsator shaft8, and the holding recess150ain the pulley15at a portion covering the rotor frame4afor being held by the braking device11.

The engagement portion15cof the pulley15has a boss shape projected from the pulley15such that the engagement portion15cis positioned on an inside of a rear end of the drum shaft6at the time of assembly of the pulley15in an assembly line.

The drum shaft6is formed of an SM45group of material, or stainless steel, wherein if the drum shaft6is formed of an SM45group of material, a surface of the drum shaft6is plated with chrome Cr for reducing wear, and friction, and enhancing corrosion resistance. In this instance, the surface of the drum shaft6is plated with chrome Cr, entirely, or partially for reduction of cost. In this case, of the surface of the drum shaft6, it is required to plate a sliding surface of the water seal12without fail.

In the meantime, it is favorable that the drum shaft6is formed of stainless steel even if it costs somewhat more, for reducing wear/friction of the slide surfaces of the water seal12and drum shaft6and securing corrosion resistance of the drum shaft6, positively.

On a surface of the pulsator7, there are washing fins7afor increasing friction of the laundry by making the laundry, lifted up by the rotation of the drum3and fallen down, to hit the washing fins7a, and moving the laundry back and forth within the drum3.

In this instance, though it is preferable that a main surface (i.e., a surface) of the pulsator7and the washing fins7aprovided at regular intervals thereon are formed as one body, it is not necessarily so.

In the meantime, the washing fin7ahas at least one sloped surface in a radial, or circumferential direction.

The main surface of the pulsator7has a predetermined curvature, and an outside diameter around 50˜80% of the inside diameter of the drum3.

A maximum height7aof the washing fin7aof the pulsator7is 5˜15% of the outside diameter of the pulsator.

Moreover, it is preferable that the drum3and the tub2are mounted such that axes thereof are tilted at 10˜30° to ground, for convenience of introduction/taking out of laundry, and enhancing a washing effect. Also, the tilted angle of 10˜30° range can prevent occurrence of excessive vibration.

If the tilted angle exceeds 30°, to make the drum3to rotate in a state tilted much, leading the laundry leaned on a rear side of the drum3, a washing performance drops and an excessive vibration occurs in spinning due to entangling of the laundry.

Accordingly, taking this into account, it is preferable that the tilting angle of the tub2is below 30°.

In the meantime, the drum3has a plurality of lifters3aon an inside circumferential surface for lifting up the laundry. There is a distance ‘D’ of approx. 30˜90 mm between the lifter3aand the washing fin of the pulsator7, more preferably, in a range of 60 mm, for preventing the laundry from being held between the lifter3aand the pulsator7to hold rotation of the pulsator7and the drum3.

In the meantime, it is preferable that auto-balancers9each filled with liquid, such as water, or salt water, are mounted on an inside and/or outside of a front, and a rear of the drum3, for reducing vibration in spinning.

For an example, the auto-balancers9may be mounted on the inside of the front and the outside of the rear of the drum3, or the inside of the front and the rear of the drum3.

Moreover, the auto-balancer9may have a single fluid chamber, or more favorably, double, triple, or quadruple fluid chambers on concentric circles, separated between inner and outer fluid chambers, for preventing the fluid from moving between the fluid chambers.

It is favorable that the auto-balancer9has a height ‘H’ greater than a width ‘W’ for reducing vibration of the drum3.

In the meantime, together with above, of course, between an inside surface of an upper surface of the cabinet1and an outside circumferential surface of an upper side of the tub2, there may be hanging springs2afor suspending the tub2, and, between a lower side of an outside circumference of the tub2and a bottom surface of the cabinet1, there may be dampers for damping vibration of the tub2in spinning.

The operation of the drum type washing machine of the present invention will be described.

The 10˜30 degrees of tilting of the drum3and the tub2with reference to front sides ground thereof enables convenient introduction, and taking out of laundry.

That is, when it is intended to introduce or take out laundry into/from the drum3, different from the related art drum type washing machine in which the user is required to stretch one hand in a state the user squats or bends, the drum type washing machine of the present invention enables easy handling of the laundry at the time of introduction or taking out laundry into/from the drum3, owing to the tilted tub2and the drum3.

Along with such convenience, the drum type washing machine of the present invention can improve the washing performance owing to the pulsator7mounted inside of the drum3.

That is, though the related art drum type washing machine has a limitation in enhancing the washing performance since the washing is achieved only by lifting up and dropping down of the laundry with the lifters3a, the drum type washing machine of the present invention can improve the washing performance significantly because the drum type washing machine of the present invention has the pulsator7mounted therein in addition to the tilted tub2and drum3, to add impact between the pulsator7and the laundry to the action of the lifters3a, and make the back and forth movement of the laundry more active owing to the tilting of the drum3and the shape of the pulsator7.

In more detail, in a state the tub2and the drum3are tilted, and the pulsator shaft8is passed through the hollow drum shaft6and connected to the pulley15in rear of the motor, as the plunger11bis placed in (seeFIG. 3), or moved away from (seeFIG. 4), the holding recess150ain the pulley150aby the action of the solenoid11aand the compression spring11cof the braking device11fixedly secured to the rear wall of the tub2or the like following control of power applied to the braking device, the pulley15is held or released. This holding or releasing of the pulley15implies that the pulsator7is held of freed.

According to this, as the pulsator7is held or freed to be rotatable in washing, varying movement of the laundry in the drum3, the washing performance can be improved.

In the meantime, in spinning too, the plunger11bmay be placed in the holding recess150aof the pulley15, to hold the pulsator7, or the plunger11bmay be moved away from the holding recess150aof the pulley15, to leave the pulsator7rotatable.

In the spinning, if the solenoid11ais turned on to make the plunger11bto move away from the holding recess150aof the pulley15, to leave the pulsator7to spin too if the drum3spins, the spinning of the pulsator7in this time is not a forced rotation like the drum by the direct driving force. That is, the pulsator7is rotated, not synchronized with a motor speed, but at a speed almost the same with the drum3as a rotation force of the drum is transmitted to the pulsator7owing to the laundry in the drum3placed on the pulsator7.

In the meantime, along with the improvement of the washing performance, the drum type washing machine of the present invention can reduce system vibration caused by an eccentric load in the drum3effectively in spinning by providing the auto-balancers9to the front and the rear of the drum3for balancing the drum by means of fluid separate from balance weights mounted on the tub2.

Particularly, though the drum type washing machine of the present invention is liable to have greater vibration at a rear side than the related art due to the tilted tub2and the drum3, the attachment of the auto-balancers9to the inside or outside of rear of the drum3enables effective reduction of vibration of the rear side.

Moreover, as described before, the tilted tub2also requires the drum3in the tub2to be tilted, to consume less washing water filled in the drum3in washing.

For an example, owing to the tilted drum3, washing water leans on a rear side of the drum3partially, and to carry out the washing after filling the washing water only just to put the laundry gathered on the rear side under the washing water.

In the meantime, the placement of the engagement portion15cof the pulley15in the drum shaft6in assembly of the pulley15shortens a total length of the drum type washing machine.

That is, if the engagement portion15cof the pulley15can not be placed in the drum shaft6in a tilted state, though the total length becomes longer, to reduce the capacity of the drum type washing machine, the placement of the engagement portion15cof the pulley15in the drum shaft6enables to reduce the total length, leading to increase the washing capacity, relatively.

In the meantime, a control process and operation of the pulley15will be described in washing of the drum type washing machine in accordance with the first preferred embodiment of the present invention.

A process for washing by rotating the drum3in a state the pulsator7is stationary will be described with reference toFIG. 3.

Referring toFIG. 3, if the plunger11bmoves forward to position in the holding recess150aof the pulley15, the pulley15can rotate no more, to hold the pulsator7in the drum3too.

In this state, if power is applied for washing, the rotor4rotates by electro-magnetic interaction with the stator5, to rotate the drum3coupled to the rotor4with a shaft.

In this instance, the drum3may rotate in left/right directions alternately under the control of a microcomputer (not shown), and the pulsator7is stationary.

According to this, the washing is performed as the laundry is lifted by the plurality of lifters3ain the drum3and dropped by gravity, when a portion of the laundry hits the pulsator7and the washing fin7ato move forward because the drum3is tilted.

Particularly, the washing machine of the present invention has a greater back and forth movement of the laundry dropped after lifted up by the lifters3athan the related art owing to the central projection of the washing fins7aand the pulsator7. That is, the sloped surface of the washing fins7a, the main surface curvature of the pulsator7, and the tilted angle, and so on cause positional change of the laundry.

Moreover, since the drum3rotates in a tilted state, and the pulsator7is stationary, a speed difference between the rotating drum3and the stationary pulsator7causes irregular and various forms of laundry movement and circulation of the washing water.

In this instance, the washing water circulation spreads the laundry gathered on a rear side of the drum3to various directions again, to help uniform washing of the laundry.

That is, in washing, the water circulation caused by collision between the washing water and the pulsator7, and impact between the laundry and the pulsator improves a washing capability and rinsing capability of the laundry, substantially.

Different from above, a washing in a state the pulsator7is rotatable as the braking on the pulley15is released will be described with reference toFIG. 4.

Referring toFIG. 4, if power is applied to the solenoid11ato move the plunger11bbackward, while compressing the compression spring11c, the plunger11bmoves away from the holding recess150aof the pulley15, leaving the pulley15, as well as the pulsator7rotatable.

Under this state, if power is applied for washing, the rotor rotates by the electro-magnetic interaction with the stator5, to rotate the drum3coupled to the rotor4with a shaft.

In this instance, as described before, the drum3can rotate in left/right directions alternately at predetermined intervals, and the pulsator7rotates in a left, or right direction under the interference of the laundry and the washing water circulating in the drum when the drum3rotates.

Accordingly, in washing the laundry by lifting the laundry with a plurality of lifters3aon an inside of the drum3and dropping the laundry by gravity, since the drum3is tilted, a portion of the laundry collides onto the rotating pulsator7.

The laundry7collided onto the pulsator7moves forward.

That is, alike a previous description, in this case too, the drum type washing machine of the present invention causes a positional change of the laundry owing to the sloped surface of the washing fin7a, the main surface curvature of the pulsator7, and the tilted angle, to increase back and forth movement of the laundry compared to the related art in which the laundry is simply lifted up by the lifters3aand dropped.

Along with this, because the pulsator7rotates not forcibly at a fixed speed though the pulsator7is in a rotatable state, there is a speed difference between the drum3and the pulsator7, to cause irregular and various forms laundry movement and washing water circulation in this time too.

That is, even if the relative speed difference is small compared to the state the pulsator7is stationary, there is a relative speed difference between the drum3and the pulsator7, which helps the movement of the laundry, that contributes to improvement of the washing capability and the rinsing capability.

In short, the drum type washing machine of the present invention can perform washing by using a relatively great speed difference in a state the pulsator7is held to be stationary, or by using a relatively small speed difference in a state the pulsator7is released to rotate freely.

Moreover, in washing, the washing may be performed by controlling the alternating time period of the drum3to be short in which the laundry does not drop in a state the pulsator7is held or released.

A second preferred embodiment of the present invention will be described in more detail with reference toFIGS. 9 to 12.

FIG. 9illustrates a longitudinal section of a drum type washing machine in accordance with a second preferred embodiment of the present invention schematically,FIG. 10illustrates a key part section, an enlarged view of the “A” part inFIG. 9, showing a pulsator in stationary, andFIG. 11illustrates a key part section, an enlarged view of the “A” part inFIG. 9, showing a pulsator in rotation.

FIG. 12illustrates a perspective view showing the pulsator inFIG. 9as an example.

Meanwhile, the pulley and the rotor bushing in the second embodiment is identical to the first embodiment, in descriptions related thereto,FIGS. 6 to 8will be referred to.

Referring toFIGS. 9 to 12, the drum type washing machine in accordance with a second preferred embodiment of the present invention includes a tub2of plastic having a wall portion for holding washing water and securing a driving unit thereto, a front side sloped upward at a predetermined angle from ground, a hot air inlet200in an upper side of a rear wall, and a hot air outlet210in a lower side of a front surface, a drum3rotatably mounted in the tub2having hot air pass through holes300bin a rear wall, a drying duct30fixedly secured to one side of an upper side of the rear wall of the tub2, having a heater32and a fan31mounted on an inside flow passage thereof for generating hot air, a condensing duct40for removing moist from hot air discharged through the hot air outlet210in a lower portion of the front of the tub2, a hollow drum shaft6passed through the tub2, and connected to the drum3inside of the tub2for transmission of driving power from a motor to the drum, bearings113a, and113bfor supporting the hollow drum shaft6, a bearing housing113of a sleeve shape for holding the bearings113aand113b, a stator5fixedly secured to the rear wall portion of the tub2, a rotor4connected to a rear end of the drum shaft6to constitute a BLDC motor together with the stator5, a pulsator7rotatably mounted in the drum3, a pulsator shaft8mounted to pass through the hollow of the drum shaft6, having a fore end connected to the pulsator7, a pulley15in rear of the rotor4connected to a rear end of the pulsator shaft8, and a braking device11for controlling rotation of the pulsator7in the drum3by braking/releasing the pulley15.

Between the tub2and the drying duct30, there is a thermal insulation plate50for preventing direct transmission of heat from the drying duct30to the tub, and on the rear wall300of the drum, there is a spider16fixedly secured thereto for supporting the drum3.

The pulsator7has a plurality of small hot air supply holes710in a main surface (i.e., a surface) for serving as a flow passage for supplying hot air to an inside of the drum3during drying, and preventing damage to the laundry in washing.

The pulsator7has a rib700at an edge of an outside circumference bent toward the rear wall300of the drum, and there is a forming portion300ain a shape in complementary to a shape of the rib700, for cutting off an air flow toward an outer side of the pulsator7.

Moreover, on an inside of the rear wall of the tub2, there is a cutoff rib220projected toward the rear wall300of the drum, for preventing the hot air introduced thereto through the hot air inlet200of the tub2from escaping to an outer side of the drum, and the spider16has a groove160in a shape in complementary to a shape of the cutoff rib220.

This is for preventing interference between the spider16of a tripod shape and the cutoff rib. Of course, a length of the cutoff rib may be formed differently, for not providing the groove160in the spider16.

At a center of a rear side of the tub2, there is the bearing housing113insert molded thereto as one unit therewith, having the front and rear bearings113a, and113bpress fit therein for supporting the drum shaft6at a rear side of the drum3.

The stator5is fastened to the rear wall of the tub2with fastening members, such as bolts.

In the meantime, the pulsator shaft8is supported on oiless bearings800a, and800bmounted on a front and a rear of the shaft, respectively.

Though it is preferable that the bearings113aand113b, supporting the hollow drum shaft6, are mounted on a front side and a rear side of the shaft respectively for secure supporting of the shaft, there is no limit in a number of bearings.

In this instance, mounting the bearings113aand113bfar from each other on the front side and rear side of the drum shaft6is favorable for secure supporting of the shaft.

It is favorable that, of the bearings113aand113bsupporting the hollow drum shaft6, the front side bearing113aof the drum shaft6has a diameter grater than a diameter of the rear side bearing113bfor minimizing vibration of the drum3during spinning, and making strength higher.

In front of the front side bearing113aof the drum shaft6, there is a water seal12for preventing water leakage, having a spring therein for pressing the water seal12toward an outside circumferential surface of the drum shaft6.

An outside of the water seal12is supported either on the bearing housing113, or a shape of the rear wall of the tub as shown inFIGS. 10 and 11.

The braking device11includes a solenoid11asecured to the tub2, and a plunger11bmoving back and forth in the solenoid11a, so that the plunger11bbrakes or releases the pulley15depending on electric turn on/off of the solenoid11a, for braking/releasing rotation of the pulsator7.

It is preferable that an elastic member, such as a compression spring11c, is mounted in the solenoid11a.

This is for the plunger11bto be lead to a position of the holding recess150ain the pulley15automatically if the pulley15coupled to the pulsator7rotates by an interference of the laundry following rotation of the drum3while the plunger11bis kept abut with a surface around the holding recess150aby an elastic force, even if the plunger11bbecomes to be positioned away from the holding recess150because the holding recess150ain the pulley15is not aligned with the plunger11bat the time the plunger11bmoves forward for braking the pulsator7.

Different from above example in which the solenoid11ais secured to the tub2, the braking device of the solenoid11amay be secured, not to the tub2, but to other place, such as the cabinet1, with the compression spring11cand the plunger11bprovided therein, so that the back and forth movement of the plunger11bfollowing electric turn on/off of the solenoid11abrakes/releases the pulley15, thereby controlling braking/releasing rotation of the pulsator7.

In the meantime, between the drum shaft6and the rotor4, there is a rotor bushing13of plastic for engagement to the drum shaft6and the rotor frame4ain a state the rotor bushing13is positioned in rear, or front of a rotor frame4a.

The rotor bushing13includes an engagement portion13afor placing in, and engagement with the drum shaft6at a center thereof, and a coupling portion13bextended in a radial direction from a circumference of the engagement portion13afor coupling with the rotor frame4a.

It is preferable that the coupling portion13bof the rotor bushing13includes a plurality of positioning projections formed as one body therewith and projected toward the rotor frame4a, or a plurality of fastening holes131bfor fastening to the rotor frame4awith bolts.

It is preferable that reinforcing ribs13care provided further at least one of the engagement portion13aand the coupling portion13bof the rotor busing13for reinforcement.

There are serration formed on an outside circumferential surface of a rear end portion of the drum shaft6, and on an inside circumferential surface of a center of the engagement portion13aof the rotor bushing opposite thereto, for engagement with each other.

In the meantime, on an outer side of the rear wall of the drum3, there is a spider16secured thereto for supporting the rear wall300of the drum and reinforcing the strength, and at a front end portion of the drum shaft6, there is a flange600in close contact with the spider16, for fastening the drum rear wall300, the spider16, and the flange600of the drum shaft6with fastening members17passed therethrough.

The pulsator shaft8has serrations on opposite end portion for engagement with the pulsator7and the pulley15, preferably each with an involute profile surface.

The pulley15includes a rear wall portion15acovering the rear wall of the rotor frame4a, a sidewall portion15bfor covering a sidewall of the rotor frame4aof steel fabricated by pressing, an engagement portion15cat a center of the rear wall portion15afor engagement with the pulsator shaft8, and the holding recess150ain the pulley15at a portion covering the rotor frame4afor being held by the braking device11.

The engagement portion15cof the pulley15has a boss shape projected from the pulley15such that the engagement portion15cis positioned on an inside of a rear end of the drum shaft6at the time of assembly of the pulley15in an assembly line.

The drum shaft6is formed of an SM45group of material, or stainless steel, wherein if the drum shaft6is formed of an SM45group of material, a surface of the drum shaft6is plated with chrome Cr for reducing wear, and friction, and enhancing corrosion resistance. In this instance, the surface of the drum shaft6is plated with chrome Cr, entirely, or partially for reduction of cost. In this case, of the surface of the drum shaft6, it is required to plate a sliding surface of the water seal12without fail.

In the meantime, it is favorable that the drum shaft6is formed of stainless steel even if it costs somewhat more, for reducing wear/friction of the slide surfaces of the water seal12and drum shaft6and securing corrosion resistance of the drum shaft6, positively.

On a surface of the pulsator7, there are washing fins7afor increasing friction of the laundry by making the laundry, lifted up by the rotation of the drum3and fallen down, to hit the washing fins7a, and moving the laundry back and forth within the drum3.

In this instance, though it is preferable that a main surface (i.e., a surface) of the pulsator7and the washing fins7aprovided at regular intervals thereon are formed as one body, it is not necessarily so.

In the meantime, the washing fin7ahas at least one sloped surface in a radial, or circumferential direction.

The main surface of the pulsator7has a predetermined curvature, and an outside diameter around 50˜80% of the inside diameter of the drum3.

A maximum height7aof the washing fin7aof the pulsator7is 5˜15% of the outside diameter of the pulsator.

Moreover, it is preferable that the drum3and the tub2are mounted such that axes thereof are tilted at 10˜30° to ground, for convenience of introduction/taking out of laundry, and enhancing a washing effect. Also, the tilted angle of 10˜30° range can prevent occurrence of excessive vibration.

If the tilted angle exceeds 30°, to make the drum3to rotate in a much tilted state, leading the laundry leaned on a rear side of the drum3, a washing performance drops and an excessive vibration occurs in spinning due to entangling of the laundry.

Accordingly, taking this into account, it is preferable that the tilting angle of the tub2is below 30°.

In the meantime, the drum3has a plurality of lifters3aon an inside circumferential surface for lifting up the laundry. There is a distance ‘D’ of approx. 30˜90 mm between the lifter3aand the washing fin of the pulsator7, for preventing the laundry from being held between the lifter3aand the pulsator7to hold rotation of the pulsator7and the drum3.

In the meantime, it is preferable that auto-balancers9each filled with liquid, such as water, or salt water, are mounted on a front, and a rear of the drum3, for reducing vibration in spinning.

In this instance, the auto-balancers9may be mounted on the inside of the front and the outside of the rear of the drum3, or the inside of the front and the rear of the drum3, respectively.

Moreover, the auto-balancer9may have a single fluid chamber, or more favorably, double, triple, or quadruple fluid chambers on concentric circles, separated between inner and outer fluid chambers, for preventing the fluid from moving between the fluid chambers.

It is favorable that the auto-balancer9has a height ‘H’ greater than a width ‘W’ for reducing vibration of the drum3.

In the meantime, together with above, of course, between an inside surface of an upper surface of the cabinet1and an outside circumferential surface of an upper side of the tub2, there may be hanging springs2afor suspending the tub2, and, between a lower side of an outside circumference of the tub2and a bottom surface of the cabinet1, there may be dampers for damping vibration of the tub2in spinning.

The operation of the drum type washing machine in accordance with the second preferred embodiment of the present invention will be described.

The 10˜30 degrees of tilting of the drum3and the tub2with reference to front sides ground thereof enables convenient introduction, and taking out of laundry.

That is, when it is intended to introduce or take out laundry into/from the drum3, different from the related art drum type washing machine in which the user is required to stretch one hand in a state the user squats or bends, the drum type washing machine of the present invention enables easy handling of the laundry at the time of introduction or taking out laundry into/from the drum3, owing to the tilted tub2and the drum3.

Along with such convenience, the drum type washing machine of the present invention can improve the washing performance owing to the pulsator7mounted inside of the drum3.

That is, though the related art drum type washing machine has a limitation in enhancing the washing performance since the washing is achieved only by lifting up and dropping down of the laundry with the lifters3a, the drum type washing machine of the present invention can improve the washing performance significantly because the drum type washing machine of the present invention has the pulsator7mounted therein in addition to the tilted tub2and drum3, to add impact between the pulsator7and the laundry to the action of the lifters3a, and make the back and forth movement of the laundry more active owing to the tilting of the drum3and the shape of the pulsator7.

In more detail, in a state the tub2and the drum3are tilted, and the pulsator shaft8is passed through the hollow drum shaft6and connected to the pulley15in rear of the motor, as the plunger11bis placed in, or moved away from, the holding recess150ain the pulley150aby the action of the solenoid11aand the compression spring11cof the braking device11fixedly secured to the rear wall of the tub2or the like following control of power applied to the braking device, the pulley15is held or released. This holding or releasing of the pulley15implies that the pulsator7is held of freed.

According to this, as the pulsator7is held or freed to be rotatable in washing, varying movement of the laundry in the drum3, the washing performance can be improved.

In the meantime, in spinning too, the plunger11bmay be placed in the holding recess150aof the pulley15, to hold the pulsator7, or the plunger11bmay be moved away from the holding recess150aof the pulley15, to leave the pulsator7rotatable.

In the spinning, if the solenoid11ais turned on to make the plunger11bto move away from the holding recess150aof the pulley15, to leave the pulsator7to spin too if the drum3spins, the spinning of the pulsator7in this time is not a forced rotation like the drum by the direct driving force. That is, the pulsator7is rotated, not synchronized with a motor speed, but at a speed almost the same with the drum3as a rotation force of the drum is transmitted to the pulsator7through the laundry when the drum3rotates due to the laundry placed on the pulsator7.

In the meantime, in drying, the hot air produced by the heater32in the drying duct30flows along the drying duct by forced blowing of the fan31and introduced into the hot air inlet200in the upper side of the rear wall.

In this instance, the cutoff rib220projected toward the rear wall300of the drum from an inside of rear wall of the tub2cuts off the hot air introduced through the hot air inlet200of the tub2from escaping toward an outer side of the drum.

Moreover, the groove160in the spider16in a shape in complementary to a shape of the cutoff rib220prevents interference between the cutoff rib220and the spider16.

In the meantime, the hot air introduced through the hot air inlet200passes through the hot air pass through hole300bin the rear wall of the drum3, and is supplied to an inside of the drum3through the plurality of hot air supply holes710in the main surface of the pulsator7in an optimal arrangement.

In this instance, the rib700at the edge of the circumference of the outside diameter of the pulsator7bent toward the rear wall300of the drum, and the forming portion300ain a shape on the rear wall700of the drum in complementary to the shape of the rib700at the edge of the pulsator7cut off air flow to an outer side of the pulsator7effectively, thereby enabling concentration of the hot air on a center portion of the drum3.

The high temperature, high humid air, having substantially center blown along an axis of the drum and dried the laundry, is discharged through the hot air outlet210in a lower side of the front of the tub2, introduced toward the condensing duct40, and turns to a low temperature, low humid air by condensing of the cooling water supplied through a condensing water tube60as the high temperature, high humid air passes the condensing water.

Then, the air introduced toward the drying duct30re-circulates as the air passes through a flow passage of the duct, is heated by the heater therein, and supplied to the drum3again. As such a circulating process is repeated, drying of the laundry is progressed.

Thus, the application of a new drying system in which the hot air is center blown along the axis of the drum3enables the drum type washing machine of the embodiment to improve drying efficiency and drying performance as the air supplied into the drum3can reaches deep into the inside of the drum, to make uniform drying of the laundry.

That is, the hot air is introduced from the drying duct30into the drum3through an upper portion of the rear of the tub2, flows through the drum3, and discharged through a lower portion of the front of the tub2. Accordingly, the hot air is supplied deep into the inside of the drum3uniformly, to improve the drying efficiency, and drying performance.

Different from a related art drum type washing machine and dryer, the connection of the drying duct30to the tub2resolves the problem of wear and tear of the gasket20.

Moreover, the connection of the drying duct30to the tub2makes an upper side and a lower side of the gasket20exact symmetry, enabling the gasket20to absorb vibration of the tub2, uniformly.

Furthermore, since the hot air is introduced into the drum3through the tub2without passing through the gasket20, different from the related art, the problem of unnecessary heating of the door is resolved.

The securing of the drying duct30and the condensing duct40to the tub2enables to dispense with a separate flexible member at a connection portion between the drying duct30and the tub2like the related art.

The drying duct30attached to the tub2also serves as a balancer weight, to improve a balance sustaining capability of the tub.

Moreover, the effective arrangement of the hot air pass through holes300bin the rear wall300of the drum can maximize a flow rate of the hot air introduced into the drum3while strength of the drum3.

In the meantime, along with the improvement of the washing and the drying performance, the drum type washing machine of the present invention can reduce system vibration caused by an eccentric load in the drum3effectively in spinning by providing the auto-balancers9to the front and the rear of an inside of the drum3for balancing the drum by means of fluid separate from balance weights mounted on the tub2.

Particularly, though the drum type washing machine of the embodiment is liable to have greater vibration at a rear side than the related art due to the tilted tub2and the drum3, the attachment of the auto-balancers9to the inside or outside of rear of the drum3enables effective reduction of vibration of the rear side.

Moreover, as described before, the tilted tub2also requires the drum3in the tub2to be tilted, to consume less washing water filled in the drum3in washing.

For an example, owing to the tilted drum3, washing water leans on a rear side of the drum3partially, and to carry out the washing after filling the washing water only just to put the laundry gathered on the rear side under the washing water.

In the meantime, the placement of the engagement portion15cof the pulley15in the drum shaft6in assembly of the pulley15shortens a total length of the drum type washing machine.

That is, if the engagement portion15cof the pulley15can not be placed in the drum shaft6in a tilted state, though the total length becomes longer, to reduce the capacity of the drum type washing machine, the placement of the engagement portion15cof the pulley15in the drum shaft6enables to reduce the total length, leading to increase the washing capacity, relatively.

In the meantime, a control process and operation of the pulley15will be described in washing or drying of the drum type washing machine in accordance with the preferred embodiment of the present invention.

A process for washing or drying by rotating the drum3in a state the pulsator7is stationary will be described with reference toFIG. 10.

Referring toFIG. 10, if the plunger11bmoves forward to position in the holding recess150aof the pulley15, the pulley15can rotate no more, to hold the pulsator7in the drum3too.

In this state, if power is applied for washing, the rotor4rotates by electro-magnetic interaction with the stator5, to rotate the drum3coupled to the rotor4with a shaft.

In this instance, the drum3may rotate in left/right directions alternately under the control of a microcomputer (not shown), and the pulsator7is stationary.

According to this, the washing is performed as the laundry is lifted by the plurality of lifters3ain the drum3and dropped by gravity, when a portion of the laundry hits the pulsator7and the washing fin7ato move forward because the drum3is tilted.

Particularly, the washing machine of the present invention has a greater back and forth movement of the laundry dropped after lifted up by the lifters3athan the related art owing to the central projection of the washing fins7aand the pulsator7. That is, the sloped surface of the washing fins7a, the main surface curvature of the pulsator7, and the tilted angle, and so on cause positional change of the laundry.

Moreover, since the drum3rotates in a tilted state, and the pulsator7is stationary, a speed difference between the rotating drum3and the stationary pulsator7causes irregular and various forms of laundry movement and circulation of the washing water.

In this instance, the washing water circulation spreads the laundry gathered on a rear side of the drum3to various directions again, to help uniform washing of the laundry.

That is, in washing, the water circulation caused by collision between the washing water and the pulsator7, and impact between the laundry and the pulsator improves a washing capability and rinsing capability of the laundry, substantially.

Different from above, a washing and drying in a state the pulsator7is rotatable as the braking on the pulley15is released will be described with reference toFIG. 11.

Referring toFIG. 11, if power is applied to the solenoid11ato move the plunger11bbackward, while compressing the compression spring11c, the plunger11bmoves away from the holding recess150aof the pulley15, leaving the pulley15, as well as the pulsator7rotatable.

Under this state, if power is applied for washing, the rotor rotates by the electro-magnetic interaction with the stator5, to rotate the drum3coupled to the rotor4with a shaft.

In this instance, as described before, the drum3can rotate in left/right directions alternately at predetermined intervals, and the pulsator7rotates in a left, or right direction under the interference of the laundry and the washing water circulating in the drum when the drum3rotates.

Accordingly, in washing the laundry by lifting the laundry with a plurality of lifters3aon an inside of the drum3and dropping the laundry by gravity, since the drum3is tilted, a portion of the laundry collides onto the rotating pulsator7.

The laundry7collided onto the pulsator7moves forward.

That is, alike a previous description, in this case too, the drum type washing machine of the present invention causes a positional change of the laundry owing to the sloped surface of the washing fin7a, the main surface curvature of the pulsator7, and the tilted angle, to increase back and forth movement of the laundry compared to the related art drum type washing machine in which the laundry is simply lifted up by the lifters3aand dropped.

Along with this, because the pulsator7rotates not forcibly at a fixed speed though the pulsator7is in a rotatable state, there is a speed difference between the drum3and the pulsator7, to cause irregular and various forms laundry movement and washing water circulation in this time too.

That is, even if the relative speed difference is small compared to the state the pulsator7is stationary, there is a relative speed difference between the drum3and the pulsator7, which helps the movement of the laundry, that contributes to improvement of the washing capability and the rinsing capability.

In short, the drum type washing machine of the present invention can perform washing by using a relatively great speed difference in a state the pulsator7is held to be stationary, or by using a relatively small speed difference in a state the pulsator7is released to rotate freely.

Moreover, in washing, the washing may be performed by controlling the alternating time period of the drum3to be short in which the laundry does not drop in a state the pulsator7is held or released.

In the meantime, the drum type washing machine of the present invention can perform spinning or drying in a state the pulsator7is fixed unable to rotate, or freed to rotate as it likes by controlling the braking device11.

The present invention is not limited to above embodiments, but variations and modifications in a variety of forms are possible as far as the variations and modifications do not depart from a scope of technical aspect of the present invention.

For an example, a small sized pulsator may be rotatably mounted on an inside circumference of the drum3.

INDUSTRIAL APPLICABILITY

As has been described, the drum type washing machine in accordance with first, or second preferred embodiment of the present invention can improves product reliability of the user as the tilted tub enables easy introduction and taking out of the laundry, and to reduce consumption of water in washing.

Particularly, the rotation of the drum in a tilted state, and the provision of pulsator inside of the drum vary movement of the laundry and water circulation within the drum, which improves a washing performance.

That is, the positional change of the laundry caused by the sloped surface of the washing fins and the slope of the main surface of the pulsator makes back and forth movements of the laundry more active than the related art in which the laundry is merely lifted up by the lifters and dropped, to vary the movements of the laundry, and the water circulation, which improves a washing performance.

Moreover, the application of a new drying system in which hot air is center blown along an axis of the drum permits the air to penetrate deep into an inside of the drum, to improve a drying efficiency, and a drying performance.

The connection of the drying duct to the tub, making the gasket arranged in an exact symmetry permits uniform absorption of vibration of the tub, and, different from the related art, resolves the problem of unnecessary heating of the door.

The drying duct also serving as a balance weight improves a balance sustaining capability of the tub.

In the meantime, along with the improvement of the washing and drying performance, the provision of auto-balancers to a front and a rear of the drum for maintaining balance of the drum by means of fluid in addition to the balance weights mounted on the tub permits effective reduction of system vibration caused by en eccentric load in the drum during spinning.