US20120117735A1

US20120117735A1 - System for and method of detecting imbalance of a laundry machine

Info

Publication number: US20120117735A1
Application number: US12/946,911
Authority: US
Inventors: John R. Holden
Original assignee: BSH Home Appliances Corp
Current assignee: BSH Home Appliances Corp
Priority date: 2010-11-16
Filing date: 2010-11-16
Publication date: 2012-05-17
Also published as: CA2756323A1

Abstract

A system and method of using a fluid flow sensor for detection of load imbalance in a laundry machine. The invention includes a laundry machine, wherein the laundry machine includes a housing; a tub disposed in the housing; a drum rotatably disposed in the tub; a motor to rotate the drum; an outflow orifice at substantially the lowest point of the tub; a pump for draining the tub of water during a dewatering phase; and an outflow line between the outflow orifice and the pump. The system further includes a fluid flow sensor disposed inline with the outflow line, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and a controller adapted to measure motor speed variation and/or fluid flow rate variation, wherein the controller initiates an imbalance routine when a threshold value of variation in motor speed or fluid flow rate is exceeded.

Description

FIELD OF THE INVENTION

The present invention relates to a system for and method of detecting imbalance of a laundry machine. More particularly, the present invention relates to using a fluid flow sensor to facilitate detection of load imbalance in a laundry machine during operation.

BACKGROUND OF THE INVENTION

Domestic appliances in use today are designed to handle a heavy load of clothing to be cleaned. Due to the larger capacities of today's machines, special attention has to be given to the structural strength and operational controls of the machines to ensure their proper and safe operations.
In particular, load balancing is an important concern for laundry machines. A laundry machine typically has a wash drum for receiving a laundry load. After the washing and rinsing cycles are done, water is extracted from the clothing by spinning the drum at a relatively high speed. To effectively remove the water from the clothing, the rotational speed of the drum during the dewatering phase can be quite high, and can generate significant centrifugal force. When laundry is not evenly distributed within the laundry machine, the imbalance can cause significant vibrations of the drum that may result in severe mechanical stress and even structural damage to the machine, especially during the dewatering phase.
In one current approach to solve the problem, variation in motor speed is used. In this approach, the variation in motor speed occurring in one revolution of the wash drum is measured and compared to a limit value. If the limit value is exceeded the drum rotation is stopped, thereby redistributing the laundry load. However, in this conventional method, because the amount of vibrations is not directly measured, but rather imbalance is detected by variation in motor speed, a problem arises in that an abnormal vibration may be generated with respect to loads whose imbalance mass is hardly sensed through variation in motor speed. Thus, this approach may not accurately detect imbalance. Other current approaches, such as using pressure sensors mounted in a fluid transfer line to sense pressure variances in fluid flow to detect vibration of the tub during operation, require the use of pressure sensors or other costly equipment.
In accordance with the present invention, such disadvantages are avoided by providing a novel system and method of detecting imbalance of a laundry machine, which can be used to provide an alternate and potentially more cost effective means of detecting a load imbalance in a laundry machine during operation to prevent excessive mechanical stress and structural damage to the laundry machine.

SUMMARY OF THE INVENTION

In one aspect, the invention is directed to a system for detecting load imbalance in a laundry machine that includes a laundry machine, wherein the laundry machine includes a housing; a tub disposed in the housing; a drum rotatably disposed in the tub; a motor adapted to rotate the drum; an outflow orifice positioned at substantially the lowest point of the tub; a pump for draining the tub of at least water during a dewatering phase; and an outflow line providing a fluidic connection between the outflow orifice and the pump. The system may further include a fluid flow sensor disposed inline with, and in fluidic connection with the outflow line of the laundry machine, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and a controller adapted to measure at least motor speed variation of the motor and fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in motor speed or fluid flow rate is exceeded.
In another aspect, the invention is directed to a system for detecting load imbalance in a laundry machine that includes a laundry machine, wherein the laundry machine includes a housing; a tub disposed in the housing; a drum rotatably disposed in the tub; a motor adapted to rotate the drum; an outflow orifice positioned at substantially the lowest point of the tub; a pump for draining the tub of at least water during a dewatering phase; and an outflow line providing a fluidic connection between the outflow orifice and the pump. The system may further include a fluid flow sensor disposed inline with, and in fluidic connection with the outflow line of the laundry machine, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and a controller adapted to measure at least fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation fluid flow rate is exceeded.
In yet another aspect, the invention is directed to a method of detecting load imbalance in a laundry machine that includes providing a system for detecting load imbalance in a laundry machine. The system may include a laundry machine, wherein the laundry machine includes a housing; a tub disposed in the housing; a drum rotatably disposed in the tub; a motor adapted to rotate the drum; an outflow orifice positioned at substantially the lowest point of the tub; a pump for draining the tub of at least water during a dewatering phase; an outflow line providing a fluidic connection between the outflow orifice and the pump; a fluid flow sensor disposed inline with, and in fluidic connection with the outflow line of the laundry machine, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and a controller adapted to measure at least motor speed variation data of the motor and fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in motor speed or fluid flow rate is exceeded. The method may further include measuring at least the motor speed variation of the motor and the fluid flow rate variation as sensed by the fluid flow sensor; determining when the variation in motor speed or fluid flow rate exceeds a threshold value; and initiating the imbalance routine when the variation in motor speed or fluid flow rate exceeds a threshold value.
In still yet another aspect, the invention is directed to a method of detecting load imbalance in a laundry machine that includes providing a system for detecting load imbalance in a laundry machine. The system may include a laundry machine, wherein the laundry machine includes a housing; a tub disposed in the housing; a drum rotatably disposed in the tub; a motor adapted to rotate the drum; an outflow orifice positioned at substantially the lowest point of the tub; a pump for draining the tub of at least water during a dewatering phase; an outflow line providing a fluidic connection between the outflow orifice and the pump; a fluid flow sensor disposed inline with, and in fluidic connection with the outflow line of the laundry machine, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and a controller adapted to measure at least fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in fluid flow rate is exceeded. The method may further include measuring at least the fluid flow rate variation as sensed by the fluid flow sensor; determining when the variation fluid flow rate exceeds a threshold value; and initiating the imbalance routine when the variation in fluid flow rate exceeds a threshold value.
In a more specific aspect, the fluid flow sensor may preferably be disposed inline with, and in fluidic connection with, the outflow line of the laundry machine, and may be positioned at a point between the outflow orifice and the pump. The fluid flow sensor may alternatively be positioned on an outlet end of the pump.
In another more specific aspect, the imbalance routine may include stopping rotation of the drum to redistribute a laundry load.
In yet another more specific aspect, the controller may be adapted to measure the variation in motor speed occurring in one revolution of the drum.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of embodiments of the present invention will be better understood after a reading of the following detailed description, together with the attached drawings, wherein:

FIG. 1 is a perspective view of a laundry machine with an imbalance detection system in accordance with an exemplary embodiment the invention;

FIG. 2A is an illustrative view of a balanced load fluid flow during operation;

FIG. 2B is an illustrative view of an imbalanced load fluid flow during operation;

FIG. 3A is a graphical illustration of balanced load fluid flow rate variation over time during operation; and

FIG. 3B is a graphical illustration of imbalanced load fluid flow rate variation over time during operation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described more fully below with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The general manner in which laundry machine 100 of FIG. 1 operates is well known in the art and, therefore, a full description of its operation will not be made here. The invention disclosed herein is not necessarily limited to implementation in a vertical axis washing machine. Inasmuch as the invention is a laundry machine having a unique load imbalance detection capability, the invention may be equally applied in a horizontal or tilted axis washing machine. Moreover, the invention may be practiced in a variety of machines which may include different motor and transmission arrangements, pumps, recirculation arrangements, agitators or impellers, or controls.
Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a laundry machine 100 having a housing 105 including a tub 110 mounted therein. Tub 110 includes drum 115 disposed in a rotatable manner therein. Laundry machine 100 also includes a motor (not shown) adapted to rotate drum 115. Tub 110 is provided at substantially its lowest point with an outflow orifice 125, to which is connected in a liquid-tight manner with an outflow line 140, which in turn is further connected in a liquid-tight manner to a pump 135. Pump 135 is provided to control the level of washing fluid within tub 110, particularly the draining of water 120 from tub 110. Outflow line 140 includes a fluid flow sensor 130, disposed inline with and in fluid connection with outflow line 140. Fluid flow sensor 130 is preferably positioned at a point between outflow orifice 125 and pump 135. Alternatively, fluid flow sensor 130 may be positioned on at outlet end of pump 135, i.e., positioned at a point after pump 135. Laundry machine 100 further includes controller 145 adapted to receive data (including, but not limited to signal(s), motor speed variation, and/or fluid flow rate variation), at least from fluid flow sensor 130 and the motor of laundry machine 100. Controller 145 preferably includes control software (not shown) to facilitate a load rebalance routine when an imbalanced load is detected in laundry machine 100.
In operation, during a spin or water extraction phase (dewatering phase) of a washing operation, drum 115 is adapted to be rotated at increasingly high speeds. When a predetermined speed is reached, e.g., at a speed in the range of about 100 rpm-500 rpm, pump 135 is activated. Pump 135 functions to pump water 120 out of tub 110 through outflow line 140 via outflow orifice 125 during the dewatering phase of a washing operation. In a preferred embodiment, fluid flow sensor 130 disposed inline with, and in fluid connection with, outflow line 140, senses the flow rate of water 120 within outflow line 140 during the dewatering phase.
With reference to FIGS. 2 and 3, in FIG. 2A a balanced flow of water 120 within outflow line 140 is shown by balanced flow arrow 205 illustrating that the flow rate of water 120, within outflow line 140, is substantially constant during the dewatering phase of a washing operation when laundry machine 100 has a balanced load. In FIG. 2B, an imbalanced flow rate of water 120 within outflow line 140 is shown by imbalanced flow arrow 210 illustrating the flow rate of water 120, within outflow line 140, is not constant, but rather is variable (e.g., water 120 is sloshing about, or at least varying in rate, in outflow line 140 due to vibrations of tub 110 caused by the imbalanced load), during the dewatering phase of a washing operation when laundry machine 100 has an imbalanced load. This is further illustrated in FIGS. 3A-B. FIG. 3A graphically illustrates by line 305 a fluid flow rate that is substantially constant over time under balanced load conditions during the dewatering phase. In contrast, FIG. 3B illustrates by line 310 a fluid flow rate that is variable over time under imbalanced load conditions during the dewatering phase.
In operation, fluid flow sensor 130 senses the flow rate of water 120 that prevails in outflow line 140 and that, for its part, is impacted, at least in part, by vibrations of tub 110. As a result, vibrations in tub 110, caused by load imbalance for example, may be detected by fluid flow sensor 130. During the dewatering phase, the fluid flow rate in outflow line 140 is sensed by fluid flow sensor 130 and fluid flow rate variation sensed by fluid flow sensor 130, may be measured by controller 145. Controller 145 preferably includes an imbalance control system and software (not shown). In one embodiment, the imbalance control system and software, in addition to the fluid flow rate variation received from fluid flow sensor 130, is adapted to measure the variation in motor speed occurring in one revolution of drum 115 and compares it to a limit value, which if exceeded, may indicate a load imbalance state of laundry machine 100. In a preferred embodiment, fluid flow sensor 130 is adapted to be in communication with the imbalance control system and software of controller 145. The imbalance control system and software of controller 145 measures the variation in motor speed in one revolution of drum 115 and compares it to a limit value. If the variation in motor speed exceeds the limit value, then controller 145 initiates the imbalance control system and software to run a rebalance routine (e.g., stops drum 115 rotation, thereby redistributing the laundry load). If the limit value has not been exceeded, then prior to accelerating the drum at higher speeds through resonance, the imbalance control system and software of controller 145 measures the variation in the flow rate of water 120 as sensed by fluid flow sensor 130 and generates a final imbalance value (i.e., flow rate variation), and compares the final imbalance value to a limit value. If the final imbalance value exceeds the limit value, then controller 145 initiates the imbalance control system and software to run a rebalance routine (e.g., stops drum 115 rotation, thereby redistributing the laundry load).
In another embodiment, fluid flow sensor 130 may be used independently of, or in place of, measuring the variation in motor speed to determine load imbalance. In such an embodiment, during the dewatering phase, the imbalance control system and software of controller 145 measures the variation in the flow rate of water 120 as sensed by fluid flow sensor 130, and generates a flow rate variation value and compares it to a limit value. If the flow rate variation value exceeds the limit value, then controller 145 initiates the imbalance control system and software to run a rebalance routine (e.g., stops drum 115 rotation, thereby redistributing the laundry load).
The use of fluid flow sensor 130 with imbalance control system and software of controller 145 results in improved performance and reliability of laundry machine 100 by more reliably preventing an excessively imbalance load from spinning and to allow redistribution of the load in the event of an imbalance.
The present invention has been described in terms of exemplary embodiments. However, modifications and additions to these embodiments are apparent to those of ordinary skill in the art. It is intended that all such modifications and additions comprise a part of the present invention.

Claims

1. A system for detecting load imbalance in a laundry machine, comprising:

a laundry machine, wherein the laundry machine comprises:

a housing;

a tub disposed in the housing;

a drum rotatably disposed in the tub;

a motor adapted to rotate the drum;

an outflow orifice positioned at substantially the lowest point of the tub;

a pump for draining the tub of at least water during a dewatering phase; and

an outflow line providing a fluidic connection between the outflow orifice and the pump;

a fluid flow sensor disposed inline with, and in fluidic connection with, the outflow line of the laundry machine, wherein the fluid flow sensor senses fluid flow rate variation within the outflow line; and

a controller adapted to measure at least motor speed variation of the motor and fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in motor speed or fluid flow rate is exceeded.

2. The system of claim 1, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at a point between the outflow orifice and the pump.

3. The system of claim 1, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at an outlet end of the pump.

4. The system of claim 1, wherein the imbalance routine comprises stopping rotation of the drum to redistribute a laundry load.

5. The system of claim 1, wherein the controller is adapted to measure the variation in motor speed occurring in one revolution of the drum.

6. A system for detecting load imbalance in a laundry machine, comprising:

a laundry machine, wherein the laundry machine comprises:

a housing;

a tub disposed in the housing;

a drum rotatably disposed in the tub;

a motor adapted to rotate the drum;

an outflow orifice positioned at substantially the lowest point of the tub;

a pump for draining the tub of at least water during a dewatering phase; and

a controller adapted to measure at least fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in fluid flow rate is exceeded.

7. The system of claim 6, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at a point between the outflow orifice and the pump.

8. The system of claim 6, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at an outlet end of the pump.

9. The system of claim 6, wherein the imbalance routine comprises stopping rotation of the drum to redistribute a laundry load.

10. A method of detecting load imbalance in a laundry machine, comprising:

providing a system for detecting load imbalance in a laundry machine, comprising:

a laundry machine, wherein the laundry machine comprises:

a housing;

a tub disposed in the housing;

a drum rotatably disposed in the tub;

a motor adapted to rotate the drum;

an outflow orifice positioned at substantially the lowest point of the tub;

a pump for draining the tub of at least water during a dewatering phase; and

a controller adapted to measure at least motor speed variation of the motor and fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in motor speed or fluid flow rate is exceeded;

measuring at least the motor speed variation of the motor and the fluid flow rate variation as sensed by the fluid flow sensor;

determining when the variation in motor speed or fluid flow rate exceeds a threshold value; and

initiating the imbalance routine when the variation in motor speed or fluid flow rate exceeds a threshold value.

11. The method of claim 10, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at a point between the outflow orifice and the pump.

12. The system of claim 10, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned on an outlet end of the pump.

13. The method of claim 10, wherein the imbalance routine comprises stopping rotation of the drum to redistribute a laundry load.

14. The method of claim 8, wherein measuring at least the motor speed variation of the motor comprises measuring the variation in motor speed occurring in one revolution of the drum.

15. A method of detecting load imbalance in a laundry machine, comprising:

a laundry machine, wherein the laundry machine comprises:

a housing;

a tub disposed in the housing;

a drum rotatably disposed in the tub;

a motor adapted to rotate the drum;

an outflow orifice positioned at substantially the lowest point of the tub;

a pump for draining the tub of at least water during a dewatering phase; and

a controller adapted to measure at least fluid flow rate variation as sensed by the fluid flow sensor, wherein the controller initiates an imbalance routine when a threshold value of variation in fluid flow rate is exceeded;

measuring at least the fluid flow rate variation as sensed by the fluid flow sensor;

determining when the variation in fluid flow rate exceeds a threshold value; and

16. The method of claim 15, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned at a point between the outflow orifice and the pump.

17. The system of claim 15, wherein the fluid flow sensor is disposed inline with, and in fluidic connection with the outflow line of the laundry machine, and is positioned on an outlet end of the pump.

18. The method of claim 15, wherein the imbalance routine comprises stopping rotation of the drum to redistribute a laundry load.