JPH03118096A - Water level detector for washing machine - Google Patents

Abstract

PURPOSE:To detect the water level of a washing tank with simple configuration without providing an air hose by detecting a resistance value between electrodes provided on the both sides of a pressure detection body by utilizing a change in the resistance value of a pressure sensitive conductive rubber caused by the pressure of water in the washing tank. CONSTITUTION:A pressure detection body 23 is composed of a pressure sensitive conductive rubber 20, for which the resistance value in a thickness direction is changed according to the amount of distortion in the thickness direction, and electrodes 21 and 22 arranged on the both sides of the pressure sensitive conductive rubber 20 by a suitable adhering means. When the water is fed into a washing tank 1 and the water level is made higher than an opening part 9, the water pressure is impressed to a seal member 25 and the pressure sensitive conductive rubber 20 is compressed in the thickness direction. Generally, the pressure sensitive conductive rubber 30 is equipped with a character that the resistance value is lowered when it is compressed, and accordingly, the more the water pressure is increased, the more the resistance value between terminals 26 and 27 is reduced. Since the resistance value is widely changed together with the water level, the water level can be detected with high accuracy.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a water level detection device for a washing machine.

Conventional technology The conventional method for detecting the water level in washing machines was to install an air trap at the bottom of the washing tub, transmit the pressure from the air trap with an air hose, and detect this with a pressure detection device. The system was designed to detect the water level.

Problems to be Solved by the Invention However, such conventional methods require an air hose to transmit water pressure from the trap at the bottom of the washing tub to the pressure detection device, which increases the number of parts and assembly man-hours, and increases the number of man-hours. There were problems in terms of cost and reliability, such as measures to seal hose joints.

The present invention has been made in consideration of the above-mentioned problems with the conventional configuration, and firstly, it provides a water level detection device for a washing machine that can detect the water level of a washing tub with a simple configuration and without providing an air hose. The purpose is to provide Second, in relation to the first object, it is an object of the present invention to provide a water level detection device for a washing machine that can perform water level detection with even higher accuracy and can be easily assembled. Thirdly, in addition to the first and second purposes above, -
It is an object of the present invention to provide a water level detection device for a washing machine that can detect water level with high layer accuracy. A fourth object of the present invention is to provide a water level detection device for a washing machine that is configured to more reliably achieve the third object.

Means for Solving the Problems The first means for achieving the first object is to use a pressure-sensitive conductive rubber formed in a sheet shape and a pair of pressure-sensitive conductive rubber provided on both sides of the pressure-sensitive conductive rubber. a pressure sensing body comprising an electrode; a case supporting the pressure sensing body; This water level detection device for a washing machine is constructed of a flexible sealing member that prevents water from leaking, and is fixed to the bottom of the washing tub by appropriate support means.

In addition to the structure of the first means, the second means for achieving the second purpose includes a pressure-sensitive conductive rubber in which the pressure sensing body is formed in a sheet shape, and a pressure-sensitive conductive rubber on the surface of the pressure-sensitive conductive rubber. The water level detection device for a washing machine is composed of a first electrode provided uniformly, and second and third electrodes provided on the back surface, and the first electrode side is in contact with a sealing member. It is something.

The third means to achieve the third purpose is the first
In addition to the configuration of the second means, the case supports the pressure sensing body at the center and has an appropriate gap in the part where the pressure sensing body and the sealing member do not contact, and furthermore, the case supports the pressure sensing body at the center and has an appropriate gap between the outside world and the pressure sensing body. The present invention provides a water level detection device for a washing machine having a vent hole to ensure ventilation.

A fourth means of the present invention is that, in addition to the configuration of the third means, the case supports the pressure sensing body at the center, and the pressure sensing body and the sealing member are not in contact with each other, and the case is provided with a pressure-sensitive conductive rubber. A water level detection device for a washing machine is provided with a flexible support member having equal elastic properties.

The first means of operation is a simple structure that detects the resistance value between the electrodes provided on both sides of the pressure sensing body by using the change in the resistance value of the pressure-sensitive conductive rubber due to the water pressure in the washing tub. This is a washing machine water level detection device that detects water level. The second means is that among the first to third electrodes provided on both sides of the pressure sensing body,
The water level is detected by detecting the resistance value between the second and third electrodes on one side and measuring the resistance between the electrodes only from one side of the pressure sensing body, which is the first means. It is possible to perform water level detection with higher accuracy than by conventional methods, and it is also easy to assemble. In the third means, with respect to the first means or the second means, the pressure sensing body is provided only in the center of the space surrounded by the sealing member and the case, and a ventilation hole is provided in the gap. Water pressure applied to the sealing member can be stably transmitted to the pressure sensing body, and highly accurate water level detection with little detection variation can be performed.

In the fourth means, with respect to the first means or the second means, the pressure sensing body is provided only in the central part of the space surrounded by the sealing member and the case, and the flexible support means is provided in the remaining part. By.

The water pressure applied to the seal member can be stably transmitted to the pressure sensing body, the water level can be detected accurately with little detection variation, and the interior can be sealed, making it a highly reliable water level sensing device. be.

Embodiment FIG. 1 is a cross-sectional view of an embodiment in which the first means of the present invention is applied to a single tank type swamp washer. ■ is a washing tank, 2 is a dehydration tank, 3 is a pulsator that stirs the clothes inside the dehydration tank 2, 4 is a motor that provides rotational driving force to the dehydration tank 2 or the pulsator 3, 6
7 is a belt that transmits the rotational driving force of the motor 4, and 7 is a belt that decelerates the rotational driving force transmitted by the belt 6 to the dewatering tank 2.
Alternatively, it is a rotation transmitting section that transmits data to the pulsator 3. Reference numeral 8 denotes a water level detection device for a washing machine, which is the main feature of this embodiment, and has an opening 9 having an appropriate shape at the bottom of the washing tub 1, and an appropriate fixing device such as a bolt to cover this opening 9. It is fixed from the outside of the washing tub 1 by a member. The water level detection device 8 has a function of receiving water pressure in the washing tub 1 and converting it into a change in resistance value. Reference numeral 10 indicates a resistance detection section that detects the resistance value of this water level detection device 8, and reference numeral 11 indicates a control section that controls the entire washing machine. The control section 11 is the resistance detection section 1
The water level in the washing tub 1 is determined based on the resistance value of the water level detection device detected by 0.

FIG. 2 shows the configuration of the water level detection device 8 described above. The figure shows an elevational view seen from inside the washing tub 1 when the water level detection device 8 is attached to the washing tub 1, and an x-x shown in the elevational view.
'Shows a cross-sectional view.

In the figure, 20 is a pressure-sensitive conductive rubber whose resistance value in the thickness direction changes depending on the amount of strain in the thickness direction. 21 and 22 are electrodes arranged on both sides of the pressure-sensitive conductive rubber 20 by appropriate adhesive means;
- 22 constitutes a pressure sensing body 23. 24
25 is a case made of rubber, for example, which serves to prevent water leakage from inside the washing tub 1 and also acts as a diaphragm to transmit the water pressure inside the washing tub 1 to the pressure sensing member 24. This is a flexible seal member. Terminals 26 and 27 are electrically connected to the electrodes 21 and 22, respectively, and are connected to the resistance detection unit 10 described above.
is for detecting the resistance value between these terminals 26 and 27. Numerals 28 to 31 are holes through which bolts for fixing the water level detection device 8 are passed, and the water level detection device 8 is fixed near the bottom of the washing tub 1 as shown in FIG. The above-mentioned opening 9 at the bottom of the washing tub 1 is opened so as to coincide with the boundary line of the bent part where the case 24 is recessed (the broken line part indicated by A in the figure).

Next, the operation of the water level detection device 8 based on this configuration will be explained. When water is supplied to the washing tub 1 and the water level becomes higher than the opening 9, water pressure is applied to the sealing member 25, and the pressure-sensitive conductive rubber 20 is compressed in the thickness direction. Generally, pressure-sensitive conductive rubber has a property that its resistance value decreases when it is compressed, and therefore, as the water pressure increases, the resistance value between the terminals 26 and 27 decreases. FIG. 3 shows the relationship between the water level of the washing tub 1 and the resistance value between the terminals 26 and 27 in this embodiment. As shown in the figure, this resistance value changes greatly with the water level, and by utilizing this, the water level can be detected with high accuracy in this embodiment.

Next, an embodiment of the second means of the present invention will be described.

Figure 4 shows its configuration. In the embodiment of the second means, the external shape is the same as that of the first means, and the mounting and the like are also the same as those shown in FIG.

FIG. 4 shows an elevational view seen from inside the washing tub 1 when the water level detection device of the second means of the present invention is attached to the washing tub 1, and an xx' cross section shown in the elevational view. The figure shows.

In the figure, 40 is a pressure-sensitive conductive rubber whose resistance value in the thickness direction changes depending on the amount of strain in the thickness direction. Reference numeral 41 denotes a first electrode uniformly disposed on one surface of the pressure-sensitive conductive rubber 40 by suitable adhesive means, and 42 and 43 are similarly disposed on the other surface of the pressure-sensitive conductive rubber 40. Second and third electrodes are provided. These pressure-sensitive conductive rubber 40 and first electrode 41. The second electrode 42 and the third electrode 43 constitute a pressure sensing body 44 . 45 is a pressure sensing body 44
A supporting case 46 is a flexible seal made of, for example, rubber, which prevents water from leaking from inside the washing tub 1 and also acts as a diaphragm to transmit the water pressure inside the washing tub 1 to the pressure sensing body 44. It is a member. 47
and 48 are terminals electrically connected to the second electrode 42 and the third electrode 43, respectively, and similarly to the embodiment of the first means, the resistance detection unit 10 detects the resistance value between these terminals 47 and 48. It is used to detect. Numerals 49 to 52 are holes for passing bolts for fixing the water level detecting device of the present invention, and the water level detecting device of this embodiment is also located near the bottom of the washing tub 1 as shown in FIG. Fixed. Similarly, the opening 9 provided near the bottom of the washing tub l is opened so as to coincide with the boundary line of the bent part where the case 45 is recessed (the broken line part indicated by A in the figure).

Next, the operation of the water level detection device of this embodiment will be explained.

When water is supplied to the washing tub 1 and the water level becomes higher than the opening 9, water pressure is applied to the sealing member 46, and the pressure-sensitive conductive rubber 40 is compressed in the thickness direction. Generally, pressure-sensitive conductive rubber has a property that its resistance value decreases when it is compressed. - The resistance between the terminals 47 and 48 in the strength tree embodiment, that is, the resistance between the second electrode 42 and the third electrode 43, can be considered as follows. Figure 5 shows its conceptual diagram. In the figure, the terminal 53 corresponds to the first electrode 41, the terminal 54 corresponds to the second electrode 42, and the terminal 55 corresponds to the third electrode 43, and 56 to 58 indicate the resistance between these electrodes. . The resistance 56 is a resistance between the first electrode and the second electrode, and this resistance mainly affects the current flowing in the thickness direction of the pressure-sensitive conductive rubber 40. Similarly, the resistance 57 is a resistance between the first electrode and the third electrode, and this resistance mainly affects the current flowing in the thickness direction of the pressure-sensitive conductive rubber 40. Resistor 58 is the resistance between the second and third electrodes, which primarily affects the current traveling across pressure sensitive conductive rubber 40 . - For boat fishing, the resistance value of the pressure-sensitive conductive rubber 40 in the thickness direction changes greatly in response to strain in the thickness direction, and by adopting such a configuration, the resistance value in the thickness direction Changes can be appropriately understood. That is, in FIG. 5, resistance 58 does not change much, but resistances 56 and 57 each change significantly. In this way, changes in the resistance value of the pressure-sensitive conductive rubber 40 can be effectively detected. Therefore, also in this embodiment, the relationship between the water level in the washing tub 1 and the resistance value between the terminals 47 and 48 is similar to that shown in FIG. 3, and the higher the water level, the lower the resistance value. Since the changes are very large, the water level can be detected with high accuracy.

Even if the negative electrode 41 is not provided, the resistance 58 shown in FIG. 5 changes to some extent, so it is not impossible to grasp the change in resistance value, and it can be used depending on the required sensitivity.

Next, an embodiment of the third means of the present invention will be described.

Figure 6 shows its configuration. In the embodiment of the third means, the external shape is the same as that of the first means and the second means, and the mounting and the like have the same structure as shown in FIG. FIG. 6 shows an elevational view seen from the inside of the washing tub 1 when the water level detection device according to the third means of the present invention is attached to the washing tub 1, and a sectional view taken along the line xx' shown in the elevational view. It shows. In the figure, 60 is a pressure-sensitive conductive rubber whose resistance value in the thickness direction changes depending on the amount of strain in the thickness direction.

Reference numeral 61 denotes a first electrode uniformly disposed on one surface of the pressure-sensitive conductive rubber 60 by an appropriate adhesive means;
are second and third electrodes similarly disposed on the other surface of the pressure-sensitive conductive rubber 60, respectively. The pressure sensitive conductive rubber 60, the first electrode 61, the second electrode 62, and the third electrode 63 constitute a pressure sensing body 64. 65
66 is a case that supports the pressure sensing body 64, and 66 prevents water from leaking from inside the washing tub 1, and also acts as a diaphragm that transmits the water pressure inside the washing tub 1 to the pressure sensing body 64, and is made of rubber, for example. This is a flexible seal member. 67 and 68 are terminals electrically connected to the second electrode 62 and the third electrode 63, respectively, and as in the embodiments of the first means and the second means, the resistance detection unit IO is connected to these terminals 67.・It detects the resistance value between 68 and 68. The pressure sensing body 64 is arranged at the center of the case 65, and an appropriate gap 69 is provided between the pressure sensing body 64 and the seal member 66 at the periphery of the case 65. For this reason, a ventilation hole 70 is provided to ensure ventilation of this gap 69. This ventilation hole 7
If there is no zero, the air gap 69 will be in a sealed configuration, and the air inside will expand or contract due to temperature changes, etc., and stress that acts as a disturbance will be applied to the pressure-sensitive conductive rubber 60 together with the seal member 66. be. Numerals 71 to 74 are holes through which bolts are inserted for fixing this water level detection device, and the water level detection device is fixed near the bottom of the washing tub 1 as shown in FIG. 1, as in the first means and the second means. Ru. Similarly, the opening 9 near the bottom of the washing tub 1 is opened so as to coincide with the boundary line of the bent portion where the case 65 is recessed (the broken line portion indicated by A in the figure).

Next, the operation of the water level detection device of this embodiment will be explained.

When water is supplied to the washing tub L and the water level becomes higher than the opening 9, water pressure is applied to the sealing member 66 and the pressure-sensitive conductive rubber 60 is compressed in the thickness direction.At this time, pressure is detected. Since the body 64 is in contact with only the central portion of the sealing member 66, water pressure can be applied to the pressure sensing body 64 without being affected by complicated distortions around the sealing member 66. , stable pressure detection is possible.The pressure-sensitive conductive rubber 60 has a property that its resistance value decreases when it is compressed. The resistance between the electrode 62 and the third electrode 63 also decreases as the water pressure increases, as mentioned in the explanation of the second means.

Therefore, in this embodiment as well, the water level in the washing tub 1 and the terminal 67
・The relationship between 68 and the resistance value is similar to that shown in Figure 3, and as the water level rises, the resistance value decreases, and the change is very large, so it is necessary to accurately and stably detect the water level. I can do it.

In this embodiment, the pressure sensing body 64 of the second means is used, but it goes without saying that the same effect can be obtained even if the pressure sensing body 64 of the first means is used.

Next, an embodiment of the fourth means of the present invention will be described.

FIG. 7 shows its configuration. In the embodiment of the fourth means, the external shape is the same as that of the first means, second means, and third means, and the mounting structure etc. is the same as that shown in Fig. 1. I'm taking it.

FIG. 7 shows an elevational view of the water level detection device of the present invention viewed from inside the washing tub 1, and a sectional view taken along the line xx' shown in the elevational view. In the figure, 80 is a pressure-sensitive conductive rubber whose resistance value in the thickness direction changes depending on the amount of strain in the thickness direction. Reference numeral 81 denotes a first electrode uniformly disposed on one surface of the pressure-sensitive conductive rubber 80 by suitable adhesive means, and 82 and 83 are similarly disposed on the other surface of the pressure-sensitive conductive rubber 80. Second and third electrodes are provided. The pressure sensitive conductive rubber 80, the first electrode 81, the second electrode 82, and the third electrode 83 constitute a pressure sensing body 84. 85 is a case that supports the pressure sensing body 84; 86 is a case that prevents water from leaking from inside the washing tub 1, and detects the water pressure inside the washing tub 1 using the pressure sensing body 84;
It is a flexible sealing member made of rubber, for example, and also acts as a diaphragm for transmitting the signal. 87 and 88 are terminals electrically connected to the second electrode 82 and the third electrode 83, respectively, and similar to the embodiments of the first means, second means, and third means, the resistance detection unit 10
is for detecting the resistance value between these terminals 87 and 88. The pressure sensing body 84 is arranged in the center of the case 85,
A support member 89 is provided around the periphery of the case 85 to fill the space between the case 85 and the seal member 86. This support member 8
9 is made of a flexible material, such as rubber, which has approximately the same elastic properties as the pressure-sensitive conductive rubber 80. Numerals 90 to 93 are holes for passing bolts for fixing the water level detection device of this embodiment, and as in the first means, second means, and third means, as shown in FIG. is fixed near the bottom of the Similarly, the opening 9 near the bottom of the washing tub 1
is opened so as to coincide with the boundary line of the bent portion where the case 85 is recessed (the broken line portion indicated by A in the figure).

Next, the operation of the water level detection device of this embodiment will be explained.

When water is supplied to the washing tub 1 and the water level becomes higher than the opening 9, water pressure is applied to the sealing member 86, and the pressure-sensitive conductive rubber 80 is compressed in the thickness direction. At this time, the pressure sensing body 84 contacts only the central part of the sealing member 86, and by providing the support member 89 having almost the same elastic properties as the pressure-sensitive conductive rubber 80 in the peripheral part, the pressure sensing body 84 contacts only the central part of the sealing member 86. It is possible to stably apply water pressure to the pressure sensing body 84 without being affected by complicated distortions in the parts, and highly reliable pressure detection is possible.The pressure-sensitive conductive rubber 80 is It has the property that its resistance value decreases when it is compressed.
The resistance between the terminals 87 and 88 in this embodiment, that is, the resistance between the second electrode 82 and the third electrode 83, also decreases as the water pressure increases, as described in the explanation of the second means.

Therefore, in this embodiment as well, the water level in the washing tub 1 and the terminal 87
・The relationship between 88 and the resistance value is similar to that shown in Figure 3, and as the water level rises, the resistance value decreases, and the change is very large, so the water level can be detected stably with high accuracy. I can do it.

In this embodiment, the pressure sensing body 84 of the second means is used, but it goes without saying that the same effect can be obtained even if the pressure sensing body 84 of the first means is used.

Effects of the Invention The first means utilizes changes in the resistance value of pressure-sensitive conductive rubber due to water pressure in the washing tub, detects the resistance value between electrodes provided on both sides of the pressure sensing body, and measures the water level with a simple configuration. By adopting a configuration that detects water level, the water level can be detected with the simplest configuration without introducing pressure from an air trap with an air hose as in the conventional case. This eliminates the need for air hoses, contributing to a reduction in the number of parts and assembly man-hours, and also making it possible to solve problems in terms of reliability, such as sealing the joints of the air hoses.

With respect to the first means, the second means detects the resistance value between the second and third electrodes on one side of the first to third electrodes provided on both sides of the pressure sensing body. By adopting a configuration in which the water level is detected by measuring the inter-electrode resistance only from one side of the pressure sensing body, it is possible to take out the output from only one side of the pressure sensing body, and the first In addition to the effects of this method, more accurate water level detection can be achieved. The reason for this is that the first method has the advantage that the electrode structure of the pressure sensing body can be configured very easily, whereas on the sealing member side of the pressure sensing body, the wiring from the electrode is connected to the sealing member. If it is caught between the seal member and the seal member, there is a fear that stress that causes deformation or disturbance of the seal member is likely to occur.

Although the second method increases the number of electrodes in the pressure sensing body, there is no need to worry about this since detection can be performed with only wiring from one side of the pressure sensing body. Furthermore, for the same reason, the assembly method is also simple.

In the third means, with respect to the first means or the second means, the pressure sensing body is provided only in the center of the space surrounded by the sealing member and the case, and a ventilation hole is provided in the gap. Water pressure applied to the sealing member can be stably transmitted to the pressure sensing body, and in addition to the effects of the first means, highly accurate water level detection with little detection variation can be performed. The reason for this is that in the peripheral area where the seal member is supported by the case, complex stress is generated on the seal member due to the fact that it is fixed by the case, and if there is a pressure sensor in this area, it will receive disturbance pressure due to the stress. There is also a risk that it may be affected by In the third means, this problem is avoided, and the pressure sensing body is provided only in the center of the sealing member, so that such a concern is eliminated.

In the fourth means, with respect to the first means or the second means, the pressure sensing body is provided only in the central part of the space surrounded by the sealing member and the case, and the flexible support means is provided in the remaining part. As a result, the water pressure applied to the seal member can be stably transmitted to the pressure sensing body, and in addition to the effects of the first method, highly accurate water level detection with less detection variation can be performed, and the internal structure can be sealed, making it reliable. This constitutes a highly accurate water level detection device. Compared to the third means, it has a similar effect in that the pressure sensing body is disposed only in the center of the sealing member, but the third means cannot have a sealed structure inside the water level sensing device. Therefore, depending on the conditions, there is a risk that condensation may occur inside, causing problems. With the fourth means, such a concern is eliminated since a completely sealed structure can be achieved. Further, by making the support member of a material having elastic properties substantially equal to those of pressure-sensitive conductive rubber, the effect of the third means can be made even more ideal.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an example in which the first means is applied to a single-tub washing machine, Fig. 2 shows the detailed configuration of the main parts, and A is x in B of the same figure.
-x' sectional view, B is an elevational view, FIG. 3 is a graph showing the relationship between the water level and the resistance value of the pressure sensing body, and FIG. 4 shows the detailed configuration of the main part of the embodiment of the second means, A is xx in B of the same figure
'A is a cross-sectional view, B is an elevational view, FIG. 5 is a conceptual diagram showing the resistance between the respective electrodes, FIG. x-x' sectional view, B is an elevation view,
FIG. 7 shows a detailed configuration of an embodiment of the fourth means, in which A is a sectional view taken along the line xx' in B of the same figure, and B is an elevational view. DESCRIPTION OF SYMBOLS 1... Washing tub, 8... Water level detection device, 10... Resistance detection part, 20... Pressure-sensitive conductive rubber, 21, 22...
・Electrode, 23... Pressure sensing body, 24... Case, 2
5... Seal member, 40... Pressure-sensitive conductive rubber, 41
...first electrode, 42...second electrode, 43...
Third electrode, 44... Pressure sensing body, 64... Pressure sensing body, 69... Gap, 70... Ventilation hole, 84...
Pressure sensing body, 89... support member.

Claims (4)

[Claims] (1) A pressure sensing body consisting of a sheet-shaped pressure-sensitive conductive rubber and a pair of electrodes provided on both sides of the pressure-sensitive conductive rubber, and a case that supports this pressure sensing body. , a flexible sealing member that is in contact with the pressure sensing body, transmits pressure to the pressure sensing body in response to water pressure in the washing tub, and prevents water in the washing tub from leaking; A water level sensing device for a washing machine which is secured by suitable support means. (2) The pressure sensing body includes a pressure-sensitive conductive rubber formed in a sheet shape, a first electrode provided uniformly on the surface of the pressure-sensitive conductive rubber, and a second electrode provided on the back surface of the pressure-sensitive conductive rubber. The water level detection device for a washing machine according to claim 1, further comprising a third electrode, and the first electrode side is in contact with a sealing member. (3) The case supports the pressure sensing body at the center, has an appropriate gap in the part where the pressure sensing body and the sealing member do not contact, and further has a ventilation hole to ensure ventilation between this appropriate gap and the outside world. The water level detection device for a washing machine according to claim 1 or 2, comprising: (4) Claim 1, wherein the case supports the pressure sensing body at a central portion, and a flexible support member having elastic properties substantially equal to that of pressure-sensitive conductive rubber is provided in a portion where the pressure sensing body and the sealing member do not come into contact with each other. Or the washing machine water level detection device according to 2.