Title of Invention

"WASHING MACHINE"

Abstract

In an inventive washing machine, a circulation passage is formed extending vertically from a suction port 22 at the bottom of a washing tub 3 to a spouting port 23 at the middle of the side wall of the washing tub 3. A filtering chamber 45 is formed by attaching a filter cover to a passage wall 31, and a water introduction opening 33 leading to the filtering chamber 45 is formed in the passage wall 31. A lint filter including a filter bag 52 is removably set in the filtering chamber 45. When the pulsator 5 is rotated, water is pumped up from the bottom of an outer tub 2 by the pumping effect of back fins 5b of the pulsator 5, and the water is sent to the suction port 22. The water then flows upwards in a water passage 36, and some of the water is introduced into the filtering chamber 45, where waste matters borne in the water are caught by the filter bag 52. The rest of the water further flows upwards in the water passage 36, and is spouted from the spouting port 23 into the washing tub 3. Thus generating a powerful vertical water current, vertical alternation of the laundry is promoted. Since the difference in height between the suction port 22 and the spouting port 23 is small, an adequate amount of water is supplied to the filter bag 52 even when the water level in the washing tub 3 is low. Accordingly, high lint-catching efficiency is obtained irrespective of the water level.

Full Text

The present invention relates to a washing machine, particularly to a washing machine having a washing tub rotatably mounted in an outer tub. Fig. 6 is a vertical sectional view of an automatic washing machine disclosed in the Japanese Unexamined Patent Publication No. H8-66589, which shows a typical constitution of conventional washing machines having a washing tub rotatably mounted in an outer tub. Referring to Fig. 6, a washing tub 3 is sustained by a rotation shaft 4 provided at the bottom of an outer tub 2. The washing tub 3 has a cylindrical side wall having a number of perforations 3a, and a circulation passage 17 is provided to extend vertically along the side wall. The circulation passage 17 has a suction port 18 and a discharge port 19 at its lower and upper ends, respectively. The discharge port 19 is positioned beneath a balance ring 16 provided at the upper end of the side wall of the washing tub 3, and a net-like lint filter 20 is detachably attached to the discharge port 19. A pulsator 5 having radial back fins 5b on its back face is provided at a lower end of the washing tub 3 so that a space is constituted between the back face of the pulsator 5 and the bottom wall of the washing tub 3. When the pulsator 5 is rotated, the water between the bottom wall of the washing tub 3 and the bottom wall of the outer tub 2 is pumped up through water-passing holes 24 by the pumping effect of the back fins 5b. Part of the pumped water is sent to the suction port 18, is pushed upwards in the circulation passage 17, and is discharged from the discharge port 19 into the washing tub 3, where waste matters borne in the water, such as lint, are caught by the lint filter 20. The water discharged into the washing tub 3 then flows through the perforations 3a into the space between the washing tub 3 and the outer tub 2. Thus, the water circulates. By the conventional washing machine, when the level of water used for washing or rinsing is relatively high (at level LI in Fig. 6, for example), the water is pumped up into the circulation passage 17 with an adequately high flow rate, so that waste matters borne in the water are caught by the lint filter 20 efficiently. When, on the other hand, the amount of the laundry is small and, correspondingly, the water level is set relatively low (at level L2 in Fig. 6, for example), the pumping effect of the back fins 5b is low, so that the pressure for pumping water into the suction port 18 is not adequately high. As a result, the flow rate of the water pumped up into the circulation passage 17 decreases, so that the catching efficiency of waste matters by the lint filter 20 declines. Thus, an object of the present invention is to provide a washing machine wherein the catching efficiency of waste matters is maintained at a high level even when the amount of the laundry is small and washing or rinsing is performed with a relatively low water level. SUMMARY OF THE INVENTION Accordingly, the present invention proposes a washing machine including: a washing tub rotatably mounted in an outer tub; a pulsator rotatably provided at a lower end of the washing tub for constituting a pumping chamber between the back face thereof and the bottom wall of the washing tub; a plurality of back fins formed on the back face of the pulsator for pumping out water from the pumping chamber when the pulsator is rotated; a circulation passage extending along the side wall of the washing tub and having an inlet at the pumping chamber and an outlet being open to the inside of the washing tub at a level lower than a standard water level of the washing machine; and a lint-catching unit for branching a flow of water in the circulation passage and for catching solid matters borne in the flow of water. In the above description, the standard water level in the outer tub is a water level preset at about the middle of a preset range of water levels for washing or rinsing, where the water levels are preset corresponding to different amounts of the laundry. In the inventive washing machine, the pulsator provided in the lower end of the washing tub constitutes a casing-like space between the back face thereof and the bottom wall of the washing tub. In the present invention, the space is referred to as a pumping chamber because it functions as a casing of a pump. That is, when the pulsator is rotated for washing or rinsing, the water under the bottom wall of the washing tub, i.e. the water between the washing tub and the outer tub, is pumped up into the space by the pumping effect of the back fins of the pulsator rotating in the space. The pumped water flows outwards along the back face of the pulsator, and enters the circulation passage from the inlet. Then the water flows upwards in the circulation passage and is spouted from the outlet into the washing tub. Also, the water supplied to the inlet is branched by the lint-catching unit, where solid matters such as lint borne in the branched flow of water are caught. In this washing machine, the pressure required for pumping water into the circulation passage is lower than that in conventional washing machines, because the difference in height between the inlet and the outlet of the circulation passage is smaller. Accordingly, even when the level of water stored in the outer tub for washing or rinsing is relatively low, the flow rate of the water supplied through the circulation passage into the washing tub hardly decreases. Thus, the flow rate of the water passing through the lint-catching unit is maintained adequately high irrespective of the water level, so that lint and other waste matters are caught by the lint-catching unit with a constantly high efficiency. When the water level in the outer tub is higher than the standard water level, the water spouted from the outlet plunges directly into the laundry and passes it, whereby dirt or stains are effectively removed from the laundry in the washing process, and the detergent retained in the laundry is effectively extracted in the rinsing process. Thus, both washing and rinsing are carried out with higher performance. Further, by the inventive washing machine, a strong vertical water current is generated in the water by spouting water directly into the water, whereby the vertical alternation of the laundry is promoted effectively even when the amount of the laundry is large. Thus, washing or rinsing is performed evenly over the whole laundry. In a modification of the present invention, the washing machine further includes a second circulation passage extending along the side wall of the washing tub and having a second inlet at the pumping chamber and a second outlet being open to the inside of the washing tub at a level higher than a maximum water level of the washing machine. In the above description, the maximum water level in the outer tub is a water level preset at the highest of the above-described preset range of water levels. In this modification, the second circulation passage is functionally the same as the above-described conventional circulation passage. By such a constitution, some of the pumped water flows upwards in the second circulation passage and falls into the washing tub. The water fall directly strikes the laundry existing close to the surface of the water and passes through the laundry, whereby dirt or stains are effectively removed from the laundry in the washing process, and the detergent retained in the laundry is effectively extracted in the rinsing process. Further, the water fall also promotes the vertical alternation of the laundry. In this modification, a second lint-catching unit may be further provided at the second outlet, whereby the catching efficiency of lint or the like is further improved. In the inventive washing machine, the lint-catching unit may be constituted by: providing a passage wall for constituting the circulation passage in association with the side wall of the washing tub; providing a water introduction opening in the passage wall; and providing a removable lint filter into which water taken out from the circulation passage through the water introduction opening is introduced. By such a constitution, water being rid of solid matters after passing through the lint filter is supplied to the washing tub. Since the lint filter is removable, the user can easily clean it. In the above-described washing machine, a flow-resisting structure may be provided in the circulation passage so that the flow resistance of the circulation passage is larger at the downstream of the water introduction opening. By such a structure, the water pressure at around the water introduction opening increases, so that a part of the flowing water is assuredly introduced into the lint filter through the water introduction opening. In the above-described washing machine, the flow-resisting structure may include an elevation formed by elevating a part of the passage wall above the water introduction opening so that the distance between the passage wall and the side wall of the washing tub is smaller at the part than at the other part of the passage wall. By such a structure, the water flowing upwards in the circulation passage is blocked by the elevation, whereby some of the water is separated and flows into the water introduction opening. It is further preferable to shape the circulation passage to have a flat cross section and to form the elevation to cover a part of the cross section in the direction of the length. By such a structure, water flows smoothly at positions in the cross section that are away from the elevation, without being blocked by the elevation, so that the power of the water spouting from the outlet is prevented from being weakened. Such a effect can be obtained also by forming an elevation on the side wall of the washing tub. In addition, the flow-resisting structure having the above-described function may be constituted also by providing a rib having a length substantially vertical to the water flow direction or by disposing a net-like member having a proper resistance to water flow at above the water introduction opening. In the above-described washing machine, it is still preferable that a filter cover is detachably attached to the passage wall for constituting a filtering chamber in association with the passage wall, the filter cover having an opening or openings for passing water, and that the lint filter is removably set in the filtering chamber. By such a structure, since the lint filter is covered by the filter cover and is not exposed to the inside of the washing tub, the lint filter is prevented from being entangled with the laundry and being detached or unduly damaged. Since the filter cover is detachable, the user can clean the lint filter easily by detaching the filter cover and then taking out the lint filter. For the above-described structure, little additional space is required because the filtering chamber is disposed adjacent to the circulation passage with the passage wall in between. Further, the lint filter and the filter cover may be constituted so that the lint filter is detachably attached to the filter cover, and that the filter cover with the lint filter is attached to the passage wall or to the wall of the washing tub. By such a structure, the cleaning of the lint filter is more facilitated because the steps of detaching the filter cover and taking out the lint filter are accomplished at one time. The passage wall and the filter cover may be constituted so that: the passage wall has on its outside a hollow deformed toward the elevation; the filter cover has a cavity in its upper part, the cavity being deformed toward the passage wall and forming a protrusion at the side facing the passage wall; and the protrusion is engaged with the hollow of the passage wall when the filter cover is attached to the passage wall. By such a structure, the user can easily detach the filter cover by inserting a finger into the cavity and pulling it down. The cavity can have an adequate depth even without enlarging the distance between the filter cover and the passage wall. Therefore, the filtering chamber can be shaped flat and, accordingly, the filter cover can be designed not to project excessively in the washing tub. By such a structure, the laundry is hardly caught by the filter cover. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical sectional view of a washing machine embodying the present invention, viewed from a side. Fig. 2 is an enlarged end view showing the detailed structure of the section A of Fig. 1. Figs. 3A-3C are enlarged vertical sectional views showing the detailed structure of parts constituting a shorter circulation passage. Fig. 4 shows the shorter circulation passage viewed in the direction B of Fig. 2. Fig. 5 shows the main part of the shorter circulation passage viewed in the direction C of Fig. 3C Fig. 6 is a vertical sectional view of a conventional washing machine, viewed from a side. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT An embodiment of the present invention is described below, referring to Figs. 1-5. Fig. 1 is a vertical sectional view of a washing machine of the present embodiment, viewed from a side, and Fig. 2 is an enlarged end view showing the detailed structure of the section A (circulation passage 21) of Fig. 1. The washing machine has a housing 1 in which an outer tub 2 is sustained by four suspension arms (not shown). A washing tub 3 having a number of perforations 3a in its cylindrical side wall is rotatably mounted in the outer tub 2 on a rotation shaft 4 provided at the bottom of the outer tub 2. A pulsator 5 is rotatably provided in a sink-like portion at the bottom of the washing tub 3. The gap between the circumference of the pulsator 5 and the upper end of the sink-like portion is defined very narrow, so that a casinglike space (pumping chamber 3b) is formed between the pulsator 5 and the bottom wall of the washing tub 3. The driving power of a motor 6 fixed to the bottom wall of the outer tub 2 is transmitted to the washing tub 3 and the pulsator 5 via a motor pulley 7, a belt 8, a main pulley 9 and a power converter 10. At the rear part of the top of the housing 1 is provided a wat^r supply hose 11, one end of which is connected to a tap (not shown). The other end of the water supply hose 11 is connected via a supply valve 12 to a water dispenser 13 having a detergent box. To the rear part of the bottom of the outer tub 2 is connected a drain hose 14, which leads via a drain valve 15 to a drain port provided outside (not shown). A balance ring 16 is fixed to the upper end of the washing tub 3, and a longer circulation passage 17 is formed to extend vertically along the side wall of the washing tub 3 from the bottom of the washing tub 3 to a position beneath the balance ring 16. The longer circulation passage 17 has a suction port 18 and a discharge port 19 at its lower and upper ends, respectively. The suction port 18 leads to the pumping chamber 3b. A lint filter 20 for catching lint and other waste matters is detachably attached to the discharge port 19. In addition to the longer circulation passage 17, a shorter circulation passage 21 is formed to extend vertically along the side wall of the washing tub 3 from the bottom to the middle height thereof. The shorter circulation passage 21 has a suction port 22 and a spouting port 23 at its lower and upper ends, respectively. The suction port 22 leads to the pumping chamber 3b. In Fig. 1, the longer circulation passage 17 is in opposition to the shorter circulation passage 21 across the central axis of the washing tub 3. In practice, the number of the passages may be more than two and their positions may be arbitrary. For example, three circulation passages including one longer circulation passage and two shorter circulation passages may be disposed at angular intervals of 120°. Detailed structure of the shorter circulation passage 21 will be described later. The pulsator 5 has top fins 5a formed on its top face for stirring water, and back fins 5b formed on its back face. The fins on each face of the pulsator 5 extend radially at substantially equal angular intervals. Water-jet openings 5c penetrating vertically are provided in the circumference of the pulsator 5 at preset intervals. Beneath the pulsator 5 are provided water-passing holes 24 vertically penetrating the bottom wall of the washing tub 3. When water is stored in the outer tub 2 up to the level LI in Fig. 1, for example, and the pulsator 5 is rotated, the back fins 5b rotating in the pumping chamber 3b generate pumping effect. By this pumping effect, the water between the bottom wall of the washing tub 3 and the bottom wall of the outer tub 2, is pumped up through the water-passing holes 24 into the pumping chamber 3b, and the pumped water flows outwards along the back face of the pulsator 5. Some of the water is powerfully jetted upwards through the water-jet openings 5c. The rest of the water is supplied to the suction ports 18, 22 of the circulation passages 17, 21 by high pressure. The water current jetted upwards from the water-jet openings 5c moves around along with the rotation of the pulsator 5, so that the laundry existing in the lower part of the washing tub 3 evenly receives the water current from below. The water supplied to the suction port 18 flows upwards in the longer circulation passage 17, and falls from the discharge port 19 into the washing tub 3. Thus, the laundry existing close to the surface of the water in the washing tub 3 receives the water fall from above. The water supplied to the suction port 22 flows upwards in the shorter circulation passage 21, and is powerfully spouted from the spouting port 23 into the water in the washing tub 3. The laundry circling around with the water current circulating horizontally in the washing tub 3 receives the spouted water laterally. Thus, water is adequately supplied to and passes over the whole laundry, irrespective of the level where the laundry exists in the washing tub 3, so that dirt or stains are effectively removed from the laundry in the washing process, and the detergent retained in the laundry is effectively extracted in the rinsing process. Further, in addition to the horizontal water current generated by the top fins 5a, a water current circulating vertically is generated in the washing tub 3, whereby the vertical alternation of the laundry is promoted, and washing or rinsing is performed evenly. When water is discharged from the discharge port 19, the water passes the lint filter 20, and lint and other waste matters borne in the water are caught by the lint filter 20. For achieving this, it is necessary to supply water to the suction port 18 by a pressure high enough to push the water into the discharge port 19, because the difference in height between the suction port 18 and the discharge port 19 of the longer circulation passage 17 is substantially large. When, for example, washing or rinsing is performed with a relatively low water level (for example, level L2 in Fig. 1) because the amount of the laundry is small, the amount of water discharged from the discharge port 19 decreases because the pressure is low. As a result, the lint-catching efficiency by the lint filter 20 declines greatly. Hence, in the washing machine of the present embodiment, another lint filter 50 is provided to the shorter circulation passage 21. The structure of the shorter circulation passage 21 is described below, referring to Figs. 3A-5. The shorter circulation passage 21 includes: a main body 30 fixed to the side wall of the washing tub 3 (see Fig. 3C), which in association with the side wall constitutes a vertical water passage having a flat cross section; a filter cover 40 which is attached to the front of the main body 30 and constitutes a filtering chamber in association with the main body 30; and a lint filter 50 set in the filtering chamber. The main body 30 and the filter cover 40 are preferably made of synthetic resin such as polypropylene resin, for example. Referring to Figs. 3C and 5, a vertical passage wall 31 of the main body 30 is partially deformed backwards (or toward the side wall of the washing tub 3) to form a hollow portion 32, which forms an elevation at the back. A water introduction opening 33 for branching water is provided in the passage wall 31 below the hollow portion 32. Part of the passage wall 31 above the hollow portion 32 is greatly bulged forwards to form a projection 34, and the spouting port 23 extending horizontally is formed in the projection 34. Referring to Figs. 3A and 4, water-passing openings 41 are formed in the lower part of the filter cover 40. The middle of the upper part of the filter cover 40 is deeply deformed to form a hook part 42 to be engaged with the hollow portion 32. The hook part 42 has an opening at the front, into which the user can insert a finger. The hook part 42 has a ridge 43 formed on its top, which is engaged with a rib 35 formed at the edge of the projection 34 for securing the filter cover 40 to the main body 30. The lint filter 50 consists of: an annular holder 51 made of synthetic resin such as polypropylene resin; and a filter bag 52 consisting of a nylon net attached to the holder 51, as shown in Fig. 3B. In attaching the filter cover 40 to the main body 30, the holder 51 of the lint filter 50 is fitted into a socket 44 on the back of the filter cover 40 firstly, and after that the filter cover 40 is pushed onto the main body 30. Thus, the filter cover 40 is secured to the main body 30, as shown in Figs. 2 and 4. By such a structure, both a water passage 36 and a filtering chamber 45 have flat cross sections and do not project excessively into the washing tub 3, so that the laundry is not caught by the filter cover 40. When the filter cover 40 is to be detached from the main body 30, the user has only to insert a finger in the hook part 42 and pull it down toward the inside of the washing tub 3, whereby the engagement of the ridge 43 with the rib 35 is resolved, and the filter cover 40 is removed together with the lint filter 50. Thus, the user can clean the lint-filter 50 easily. In the washing machine of the present embodiment, when the pulsator 5 is rotated, water is supplied to the suction port 22 by the pumping effect of the back fins 5b. The water flows upwards in the water passage 36 formed between the passage wall 31 and the side wall of the washing tub 3, as shown by arrows Ab and Ac in Figs. 2 and 5. The space between the hollow portion 32 and the side wall of the washing tub 3 is narrower than at both sides of or below the space, so that the water flowing along the arrow Ab of Fig. 5 is blocked, and some of the water flows into the filtering chamber 45 through the water introduction opening 33. The rest of the water flowing upwards in the water passage 36 along the arrows Ac of Fig. 5, on the other hand, reaches the spouting port 23 without being blocked by the hollow portion 32, and is powerfully spouted into the washing tub 3. Thus, by forming the hollow portion 32, some of the water supplied to the suction port 22 is assuredly branched into the filtering chamber 45 without decreasing the power of spouting water from the spouting port 23. The water introduced into the filtering chamber 45 flows into the washing tub 3 through the water-passing openings 41, where waste matters borne in the water are caught by the filter bag 52 when the water passes through the filter bag 52. Since the difference in height between the suction port 22 and the spouting port 23 of the shorter circulation passage 21 is considerably small compared to that of the longer circulation passage 17, an adequate amount of water is pumped up and passes the lint filter 50 at high flow rate, even when the level of the water for washing or rinsing is low and the pressure for supplying water to the suction port 22 is correspondingly low. Thus, lint and other waste matters are caught with high efficiency. In the above-described embodiment, the water introduction opening 33 for branching water is provided in the middle of the passage wall 31. It is also possible that a water introduction opening for branching water is provided in proximity to the suction port 22 and another water passage for catching lint is formed extending from the water introduction opening to the filtering chamber 45. In the above-described embodiment, the lint filter 50 is constituted using filtering bag consisting of a nylon net. It is also possible to constitute the lint filter using a plate-like or padlike filtering member made of nonwoven fabric. It should be noted that the above-described embodiment is a mere example, and the present invention can be embodied in various ways within the spirit and scope thereof. 1. A washing machine comprising: a washing tub rotatably mounted in an outer tub; a pulsator rotatably provided at a lower end of the washing tub for constituting a pumping chamber between the back face thereof and the bottom wall of the washing tub; a plurality of back fins formed on the back face of the pulsator for pumping out water from the pumping chamber when the pulsator is rotated; a circulation passage extending along the side wall of the washing tub and having an inlet at the pumping chamber and an outlet being open to the inside of the washing tub at a level lower than a standard water level of the washing machine; and a lint-catching unit for branching a flow of water in the circulation passage and for catching solid matters borne in the flow of water. 2. The washing machine according to claim 1, further comprising a second circulation passage extending along the side wall of the washing tub and having a second inlet at the pumping chamber and a second outlet being open to the inside of the washing tub at a level higher than a maximum water level of the washing machine. 3. The washing machine according to claim 1 or 2, wherein the lint-catching unit is constituted by: providing a passage wall for constituting the circulation passage in association with the side wall of the washing tub; providing a water introduction opening in the passage wall; and providing a removable lint filter into which water taken out from the circulation passage through the water introduction opening is introduced. 4. The washing machine according to claim 3, wherein a flow-resisting structure is provided in the circulation passage so that a flow resistance of the circulation passage is larger at a downstream of the water introduction. 5. The washing machine according to claim 4, wherein the flow-resisting structure includes an elevation formed by elevating a part of the passage wall above the water introduction opening so that the distance between the passage wall and the side wall of the washing tub is smaller at the part than at the other part of the passage wall. 6. The washing machine according to claim 5, wherein a filter cover is detachably attached to the passage wall for constituting a filtering chamber in association with the passage wall, the filter cover having an opening or openings for passing water, and that the lint filter is removably set in the filtering chamber. 7. The washing machine according to claim 6, wherein the lint filter and the filter cover are constituted so that the lint filter is detachably attached to the filter cover, and that the filter cover with the lint filter is attached to the passage wall. 8. The washing machine according to claim 6 or 7, wherein the passage wall and the filter cover are constituted so that: the passage wall has on its outside a hollow deformed toward the elevation; the filter cover has a cavity in its upper part, the cavity being deformed toward the passage wall and forming a protrusion at the side facing the passage wall; and the protrusion is engaged with the hollow of the passage wall when the filter cover is attached to the passage wall. 9. A washing machine substantially as hereinbefore described with reference to the accompanying drawings.

Documents:

2820-mas-1998 abstract original.pdf

2820-mas-1998 claims granted.pdf

2820-mas-1998 description (complete) granted.pdf

2820-MAS-1998 AMANDED CLAIMS 25-02-2010.pdf

2820-MAS-1998 AMANDED PAGES OF SPECIFICATION 26-10-2009.pdf

2820-mas-1998 correspondance others.pdf

2820-MAS-1998 CORRESPONDENCE OTHERS 26-10-2009.pdf

2820-MAS-1998 OTHER DOCUMENT 26-10-2009.pdf

2820-MAS-1998 OTHER PATENT DOCUMENT 26-10-2009.pdf

2820-mas-1998- abstract.pdf

2820-mas-1998- claims.pdf

2820-mas-1998- correspondence others.pdf

2820-mas-1998- correspondence po.pdf

2820-mas-1998- description complete.pdf

2820-mas-1998- drawings.pdf

2820-mas-1998- form 1.pdf

2820-mas-1998- form 26.pdf

2820-mas-1998- form 3.pdf

2820-mas-1998- form 4.pdf

2820-mas-1998others.tif