A liquid level detection device and a washing machine having the same

Abstract

The application discloses a liquid level detection device and a washing machine with the same, wherein the liquid level detection device comprises a first container, an air pocket, a flow meter and a second container. The air pocket is located outside the first container and communicates with the inner cavity of the first container; the first container is filled with liquid in the inner cavity and further communicates with the second container through a pipeline; the flow meter is installed on the pipeline; the volume change of the air pocket is opposite to and associated with the volume change of the inner cavity of the second container; when the air pocket is compressed to increase the volume and shrink, the liquid in the first container flows into the second container; when the air pocket is rebounded to decrease the volume and reduce the pressure, the liquid in the second container flows into the first container. The flow meter installed on the pipeline can detect the liquid flow, thereby corresponding to indicate the volume change of the air pocket, the pressure, and finally reflect the liquid level in the washing barrel. The structure is simple, the installation is simple, only the liquid level detection is performed, other actions of the washing machine are not participated in, the equipment loss is reduced, and the possibility of equipment failure caused by unnecessary actions is avoided.

Description

Technical Field

[0001] This invention belongs to the field of washing machines, and more specifically, relates to a liquid level detection device and a washing machine having the same. Background Technology

[0002] Washing machines need to detect the water level in the washing tub during washing, but existing liquid level detection devices are complex in structure and inconvenient to use.

[0003] Chinese patent application number 202120258439.X discloses a liquid level detection device and a washing machine having the same. The liquid level detection device needs to perform related action control during the washing machine's water storage and drainage while detecting the liquid level. Since it is inevitable to perform other operations besides the liquid level detection function, and the water storage and drainage actions of the washing machine occur multiple times during the washing process, the operation is inconvenient and the large number of mechanisms can easily cause equipment failure.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a liquid level detection device with simple structure, convenient installation and reliable operation.

[0006] Another object of the present invention is to provide a washing machine having the above-mentioned liquid level detection device.

[0007] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0008] A liquid level detection device includes a first container, an air tank, a flow meter, and a second container.

[0009] The gas chamber is located outside the first container and is connected to the inner cavity of the first container. The first container is filled with liquid and is also connected to the second container through a pipe, on which a flow meter is installed. The volume change of the gas chamber is opposite to and related to the volume change of the inner cavity of the second container. When the gas chamber is pressurized and its volume decreases, the liquid in the first container flows into the second container. When the gas chamber is pressurized and its volume rebounds, the liquid in the second container flows into the first container.

[0010] By setting up an air chamber connected to the inner cavity of the first container and linking it to a second container via a pipe, liquid can be discharged from the first container and flow into the second container through the pipe when the pressure on the air chamber changes, causing its volume to decrease. Conversely, when the pressure on the air chamber changes, causing its volume to increase, liquid flowing into the second container can be returned to the first container through the pipe. A flow meter installed on the pipe detects the liquid flow rate during the discharge of liquid from the first container into the second container, thus indicating the change in air chamber volume and the pressure on the air chamber. Since this liquid level detection device is installed in the washing machine in contact with the water in the washing tub, the pressure on the air chamber changes due to the water level in the tub, ultimately reflecting the liquid level in the washing tub.

[0011] Furthermore, the second container has a pressure plate installed in its inner cavity, which divides the inner cavity of the second container into two parts: a first inner cavity and a second inner cavity. The first inner cavity is connected to the first container, while the second inner cavity is isolated from the first container but connected to the outside. A spring is provided between the pressure plate and the wall of the second container, and the pressure plate can move under the action of the liquid and the spring to change the size of the first inner cavity.

[0012] As the air bag increases in pressure and decreases in volume, the liquid in the first container flows into the second container. Therefore, a pressure plate is installed in the inner cavity of the second container, dividing the inner cavity of the second container into two parts: a first inner cavity and a second inner cavity. The first inner cavity is connected to the first container, while the second inner cavity is isolated from the first container but connected to the outside. In this way, when the liquid in the first container flows into the second container, it will push the pressure plate to move, thereby increasing the liquid capacity of the first inner cavity. Since the second inner cavity of the second container is isolated from the first container but connected to the outside, the pressure plate will not be resisted by air compression when it moves.

[0013] Since it is necessary to push the liquid flowing from the first container into the second container back into the first container when the pressure on the outside of the gas bag decreases, a power device needs to be installed in the inner cavity of the second container to provide power to move the pressure plate and compress the first inner cavity. In this invention, a spring is installed between the pressure plate and the wall of the second container. As the pressure on the outside of the gas bag decreases, the pressure on the liquid in the first container decreases, and the pressure transmitted by the liquid to the pressure plate in the second container decreases. As a result, the pressure plate can move under the action of the spring to reduce the size of the first inner cavity and push the liquid in the second container into the first container.

[0014] Furthermore, a spring is provided in the second inner cavity, with both ends of the spring abutting against the pressure plate and the second container wall opposite to the pressure plate, respectively.

[0015] To facilitate installation and prevent corrosion of the spring, a spring is installed in the second inner cavity, with its two ends abutting against the pressure plate and the wall of the second container opposite the pressure plate, respectively.

[0016] Furthermore, the liquid level detection device also includes a pressure plate limiting rod. A hole is provided on the wall of the second container that forms the second inner cavity and is opposite to the pressure plate. One end of the pressure plate limiting rod is fixedly connected to the pressure plate, and the other end of the pressure plate limiting rod passes through the hole. A spring is sleeved on the outside of the pressure plate limiting rod.

[0017] To ensure the stability of the pressure plate during movement and prevent liquid leakage from the first inner cavity, the liquid level detection device also includes a pressure plate limiting rod. A hole is provided in the wall of the second container, which forms the second inner cavity and is opposite to the pressure plate. One end of the pressure plate limiting rod is fixedly connected to the pressure plate, and the other end passes through the hole. A spring is sleeved on the outside of the pressure plate limiting rod. Through the limiting action of the pressure plate limiting rod and the hole, the pressure plate will not tip over during movement, thus ensuring that the liquid in the first inner cavity does not leak.

[0018] Furthermore, the spring is a compression spring.

[0019] Since the spring is installed in the second inner cavity, and the spring needs to generate force to compress the volume of the first inner cavity, a compression spring is selected here.

[0020] Furthermore, a spring is provided in the first inner cavity, with the two ends of the spring connected to a pressure plate and the second container wall opposite to the pressure plate, respectively.

[0021] To compress the volume of the first inner cavity under pressure, another approach can be adopted: a spring can be installed in the first inner cavity, with its two ends connected to the pressure plate and the wall of the second container opposite the pressure plate, respectively. Here, the spring is a tension spring.

[0022] When the pressure of the liquid in the first inner cavity on the pressure plate decreases, the tension spring retracts from its original stretched state, providing tension to the pressure plate to move it, thereby compressing the volume of the first inner cavity and pushing the liquid in the first inner cavity back into the first container.

[0023] Furthermore, an air bag is fixed to the top of the first container and is connected to it.

[0024] To better meet the compact size requirement of the washing machine, an air chamber is fixed to the top of the first container, and the air chamber is connected to the inner cavity of the first container. In this way, when the liquid level detection device is installed at the bottom of the washing tub to detect the water level in the washing machine, the air chamber located at the top of the first container can contact the liquid in the washing tub without causing a waste of overall volume.

[0025] The present invention also provides a washing machine having the above-mentioned liquid level detection device, wherein the liquid level detection device is fixed below the washing tub and the air bag can contact the water at the bottom of the washing tub.

[0026] Since the liquid flow rate is measured by changing the pressure of an air chamber to determine the water level in the washing tub, the air chamber needs to be in contact with the water at the bottom of the tub to ensure the most accurate detection. Therefore, the liquid level detection device is fixed at the bottom of the washing tub, and the air chamber is in contact with the water at the bottom of the tub.

[0027] Furthermore, a hole is provided at the bottom of the washing tub, the first container is fixedly connected to the bottom of the washing tub and the bottom of the hole is sealed, and the air bag is located in the hole.

[0028] An air tank is placed in a hole at the bottom of the washing tub, allowing the water in the tub to act on it. The hole diameter is larger than the maximum diameter of the air tank. To prevent leakage, a first container is fixedly connected to the bottom of the washing tub and the bottom of the hole is sealed.

[0029] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0030] This invention discloses a liquid level detection device and a washing machine having the same. The liquid level detection device includes a first container, an air chamber, a flow meter, and a second container. The air chamber is located outside the first container and communicates with the inner cavity of the first container. The first container is filled with liquid and is also connected to the second container via a pipe. A flow meter is installed on the pipe. The volume change of the air chamber is opposite to and correlated with the volume change of the inner cavity of the second container. When the air chamber is compressed and its volume decreases, the liquid in the first container flows into the second container; when the air chamber is compressed and its volume rebounds, the liquid in the second container flows into the first container. By setting an air chamber outside the first container and communicating with the inner cavity of the first container, and connecting it to the second container via a pipe, the liquid in the first container can be discharged from the first container and flow into the second container via the pipe when the pressure on the air chamber changes, causing its volume to decrease; or, when the pressure on the air chamber changes, causing its volume to increase, the liquid flowing into the second container can be returned to the first container via the pipe. When liquid is discharged from the first container and flows into the second container through a pipe, a flow meter installed on the pipe can detect the liquid flow rate, thereby indicating the change in the volume of the air chamber and reflecting the pressure on the air chamber. This invention also proposes a washing machine with the aforementioned liquid level detection device. Since the liquid level detection device is installed in the washing machine in contact with the water in the washing tub, the pressure on the air chamber changes due to the water level in the washing tub. Therefore, the liquid flow rate detected by the flow meter installed on the pipe ultimately reflects the liquid level in the washing tub. Its structure is simple, installation is easy, and the liquid level detection device only performs liquid level detection and does not participate in other actions of the washing machine, greatly reducing equipment wear and avoiding the possibility of equipment failure caused by participating in unnecessary actions.

[0031] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0032] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0033] Figure 1 This is a schematic diagram of the liquid level detection device of the present invention installed on a washing machine;

[0034] Figure 2 This is a schematic diagram of the liquid level detection device of the present invention when the washing tub is not filled with water;

[0035] Figure 3 This is a schematic diagram of the liquid level detection device of the present invention when the washing tub is filled with water;

[0036] Figure 4 This is a schematic diagram of the installation of the liquid level detection device in the washing machine according to Embodiment 2 of the present invention;

[0037] Figure 5 This is a schematic diagram of the liquid level detection device in Embodiment 2 of the present invention when the washing tub is not filled with water;

[0038] Figure 6 This is a schematic diagram of the liquid level detection device in Embodiment 2 of the present invention when the washing tub is filled with water.

[0039] In the diagram: 1. Washing tub; 2. First container; 3. Second container; 4. Flow meter; 5. Air tank; 6. Second pressure plate; 7. Pressure plate; 8. Spring.

[0040] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] Example 1

[0045] This invention provides a liquid level detection device, combined with Figure 1-3 As shown, it includes a first container 2, an air tank 5, a flow meter 4, and a second container 3.

[0046] The air bag 5 is located outside the first container 2 and is connected to the inner cavity of the first container 2. The first container 2 is filled with liquid and is also connected to the second container 3 through a pipe. A flow meter 4 is installed on the pipe. The volume change of the air bag 5 is opposite to and related to the volume change of the inner cavity of the second container 3. When the air bag 5 is pressurized and its volume decreases, the liquid in the first container 2 flows into the second container 3. When the air bag 5 is pressurized and its volume rebounds, the liquid in the second container 3 flows into the first container 2.

[0047] By setting an air chamber 5 connected to the inner cavity of the first container 2 externally and connected to the second container 3 via a pipe, liquid in the first container 2 can be discharged into the second container 3 through the pipe when the pressure on the air chamber 5 changes, causing its volume to decrease; conversely, liquid flowing into the second container 3 can be returned to the first container 2 through the pipe when the pressure on the air chamber 5 changes, causing its volume to increase. When liquid is discharged from the first container 2 and flows into the second container 3, a flow meter 4 installed on the pipe can detect the liquid flow rate, thus indicating the change in the volume of the air chamber 5 and reflecting the pressure on it. Since this liquid level detection device is installed in the washing machine in contact with the water in the washing tub 1, the pressure on the air chamber 5 changes due to the water level in the washing tub 1, ultimately reflecting the liquid level in the washing tub 1.

[0048] In order to make the installation and fixation of the liquid level detection device more in line with the compact size of the washing machine, an air bag 5 is fixed on the top of the first container 2, and the air bag 5 is connected to the inner cavity of the first container 2. In this way, when the liquid level detection device is installed at the bottom of the washing tub 1 to detect the water level in the washing machine, the air bag 5 located at the top of the first container 2 can contact the liquid in the washing tub 1 without causing a waste of overall volume.

[0049] The second container 3 has a pressure plate 7 installed in its inner cavity, which divides the inner cavity of the second container 3 into a first inner cavity and a second inner cavity. The first inner cavity is connected to the first container 2, while the second inner cavity is isolated from the first container 2 but connected to the outside. A spring 8 is installed between the pressure plate 7 and the wall of the second container 3. The pressure plate 7 can move under the action of the liquid and the spring 8, thereby changing the size of the first inner cavity of the second container 3 that is connected to the first container 2. Specifically, in this structure, the change in the volume of the gas bag is opposite to and related to the change in the volume of the inner cavity of the second container, meaning that the change in the volume of the gas bag is opposite to and related to the change in the volume of the first inner cavity of the second container.

[0050] To achieve better sealing, a sealing ring is provided on the outer periphery of the pressure plate 7 to achieve a seal between the outer periphery of the pressure plate 7 and the wall of the second container 3.

[0051] As the air bag 5 shrinks due to increased external pressure, the liquid in the first container 2 flows into the second container 3. Therefore, the volume of the first inner cavity of the second container, which needs to be connected to the first container 2, can increase. Thus, when the liquid in the first container 2 flows into the second container 3, it will push the pressure plate 7 to move, thereby increasing the first inner cavity of the second container connected to the first container 2. The second inner cavity of the second container 3 is isolated from the first container 2 but connected to the outside. Therefore, the pressure plate 7 will not be resisted by air compression when it moves.

[0052] Since it is necessary to push the liquid flowing from the first container 2 into the second container 3 back into the first container 2 when the pressure on the outside of the air bag 5 decreases, a power device needs to be installed in the inner cavity of the second container 3 to provide power to move the pressure plate 7 and compress the first inner cavity of the second container 3 that is connected to the first container 2. In this invention, a spring 8 is provided between the pressure plate 7 and the wall of the second container 3. As the pressure on the outside of the air bag 5 decreases, the pressure on the liquid in the first container 2 decreases, and the pressure transmitted by the liquid to the pressure plate 7 in the second container 3 decreases. As a result, the pressure plate 7 can move under the action of the spring 8 to reduce the size of the first inner cavity of the second container 3 and push the liquid in the second container 3 into the first container 2.

[0053] To facilitate installation and prevent corrosion of the spring 8, a spring 8 is installed in the second inner cavity of the second container 3. The two ends of the spring 8 abut against the pressure plate 7 and the wall of the second container 3 opposite to the pressure plate 7, respectively. Since the spring 8 is installed in the second inner cavity, and the spring 8 needs to generate force to compress the volume of the first inner cavity of the second container 3, a compression spring 8 is selected here.

[0054] like Figure 2 , 3 As shown, the liquid level detection device also includes a pressure plate limiting rod. A hole is provided on the wall of the second container 3, which forms the second inner cavity and is opposite to the pressure plate 7. One end of the pressure plate limiting rod is fixedly connected to the pressure plate 7, and the other end of the pressure plate limiting rod passes through the hole. A spring is sleeved on the outside of the pressure plate limiting rod.

[0055] To ensure the stability of the pressure plate 7 during movement and prevent leakage of liquid from the first inner cavity of the second container 3, which is connected to the first container 2, the liquid level detection device also includes a pressure plate limiting rod. A hole is provided in the wall of the second container 3, which forms the second inner cavity and is opposite to the pressure plate 7. One end of the pressure plate limiting rod is fixedly connected to the pressure plate 7, and the other end passes through the hole. A spring is sleeved on the outside of the pressure plate limiting rod. Through the limiting effect of the pressure plate limiting rod and the hole, the pressure plate 7 will not tip over during movement, thus ensuring that the liquid in the first inner cavity of the second container 3, which is connected to the first container 2, does not leak.

[0056] In other embodiments, to compress the volume of the first inner cavity under the force applied to the pressure plate, another approach can be adopted: a spring is provided in the first inner cavity, with its two ends connected to the pressure plate and the wall of the second container opposite the pressure plate, respectively. Here, the spring is a tension spring. When the pressure of the liquid in the first inner cavity on the pressure plate decreases, the tension spring retracts from its original stretched state, providing tension to the pressure plate to move it, thereby compressing the volume of the first inner cavity and forcing the liquid in the first inner cavity back into the first container.

[0057] Example 2

[0058] The difference between this embodiment and Embodiment 1 is that:

[0059] Combination Figure 4-6 As shown, a second pressure plate 6 is provided in the inner cavity of the first container 2. The diameter of the second pressure plate 6 matches the inner diameter of the first container 2, and a sealing ring is provided on the outer periphery of the second pressure plate 6.

[0060] The second pressure plate 6 divides the inner cavity of the first container 2 into two parts. One part of the inner cavity is connected to the air bag and contains air. The other part of the inner cavity is filled with liquid and is connected to the second container through a pipe.

[0061] The second pressure plate 6 can move axially along the first container 2. In order to make the movement of the second pressure plate 6 stable, a limit rod is provided on one side of the second pressure plate 6. The limit rod is inserted into the connection port between the first container 2 and the pipeline.

[0062] When the air bag is compressed, the gas enters the inner cavity of the first container 2, thereby pushing the second pressure plate 6 to move and squeezing the liquid in another part of the inner cavity of the first container 2 to be discharged outward, and discharged to the second container through the pipeline and flow meter.

[0063] The present invention also provides a washing machine having any of the above-mentioned liquid level detection devices, wherein the liquid level detection device is fixed below the washing tub 1, and the air bag 5 can contact the water at the bottom of the washing tub 1.

[0064] Since the liquid flow rate is measured by changing the pressure of the air chamber 5 to determine the water level in the washing tub 1, the air chamber 5 needs to be in contact with the water at the bottom of the washing tub 1 to ensure the most accurate detection. Therefore, the liquid level detection device is fixed below the washing tub 1, and the air chamber 5 can contact the water at the bottom of the washing tub 1.

[0065] A hole is provided at the bottom of the washing tub 1. The first container 2 is fixedly connected to the bottom of the washing tub 1 and seals the bottom of the hole. The air bag 5 is located in the hole.

[0066] A hole is provided at the bottom of the washing tub 1, and an air bag 5 is placed in the hole to contact the water at the bottom of the washing tub 1, so that the water in the washing tub 1 can act on the air bag 5. The diameter of the hole is larger than the maximum diameter of the air bag 5. To prevent leakage, a first container 2 is fixedly connected to the bottom of the washing tub 1 and seals the bottom of the hole.

[0067] During the washing machine design phase, water is added to the washing tub 1 and the water level is detected. The air chamber 5 of the liquid level detection device is compressed, and the liquid in the first container 2 is squeezed and flows through the flow meter 4 into the second container 3. The flow meter 4 calculates the flow rate. Logical calculations are performed based on the detected water level in the washing tub 1 and the liquid flow rate of the flow meter 4. Using fuzzy algorithms and digital modeling, the water level in the washing tub 1 is correlated with the liquid flow rate of the flow meter 4. The corresponding results are archived and written into the washing machine computer board control device.

[0068] When the user adds water to the washing tub 1, the air chamber 5 of the liquid level detection device is compressed by increased pressure. The liquid in the first container 2 flows to the second container 3 through the flow meter 4. The washing machine computer board control device performs logic calculations and calculates the corresponding water level height value in the washing tub 1 based on the liquid flow meter 4, and displays and transmits it to the user through the display device.

[0069] This invention discloses a liquid level detection device and a washing machine having the same. The liquid level detection device includes a first container, an air chamber, a flow meter, and a second container. The air chamber is located outside the first container and communicates with the inner cavity of the first container. The first container is filled with liquid and is also connected to the second container via a pipe. A flow meter is installed on the pipe. The volume change of the air chamber is opposite to and correlated with the volume change of the inner cavity of the second container. When the air chamber is compressed and its volume decreases, the liquid in the first container flows into the second container; when the air chamber is compressed and its volume rebounds, the liquid in the second container flows into the first container. By setting an air chamber outside the first container and communicating with the inner cavity of the first container, and connecting it to the second container via a pipe, the liquid in the first container can be discharged from the first container and flow into the second container via the pipe when the pressure on the air chamber changes, causing its volume to decrease; or, when the pressure on the air chamber changes, causing its volume to increase, the liquid flowing into the second container can be returned to the first container via the pipe. When liquid is discharged from the first container and flows into the second container through a pipe, a flow meter installed on the pipe can detect the liquid flow rate, thereby indicating the change in the volume of the air chamber and reflecting the pressure on the air chamber. This invention also proposes a washing machine with the aforementioned liquid level detection device. Since the liquid level detection device is installed in the washing machine in contact with the water in the washing tub, the pressure on the air chamber changes due to the water level in the washing tub. Therefore, the liquid flow rate detected by the flow meter installed on the pipe ultimately reflects the liquid level in the washing tub. Its structure is simple, installation is easy, and the liquid level detection device only performs liquid level detection and does not participate in other actions of the washing machine, greatly reducing equipment wear and avoiding the possibility of equipment failure caused by participating in unnecessary actions.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A liquid level detection device, characterized in that: It includes a first container, an air tank, a flow meter, and a second container. An air bag is located outside the first container and communicates with the inner cavity of the first container; The first container is filled with liquid and is connected to the second container through a pipe, on which a flow meter is installed. The change in the volume of the air bag is opposite to and correlated with the change in the volume of the inner cavity of the second container; When the air bag is compressed and its volume decreases, the liquid in the first container flows into the second container; when the air bag is compressed and its volume rebounds, the liquid in the second container flows into the first container. The second container has a pressure plate installed in its inner cavity. A sealing ring is provided on the outer periphery of the pressure plate to seal between the outer periphery of the pressure plate and the wall of the second container. The pressure plate divides the inner cavity of the second container into two parts: a first inner cavity and a second inner cavity. The first inner cavity is connected to the first container, while the second inner cavity is isolated from the first container but connected to the outside. A spring is installed between the pressure plate and the wall of the second container. The pressure plate can move under the action of the liquid and the spring to change the size of the first inner cavity. A spring is installed in the second inner cavity. The two ends of the spring abut against the pressure plate and the wall of the second container opposite to the pressure plate, respectively. The spring is a compression spring. Alternatively, a spring is installed in the first inner cavity. The two ends of the spring are connected to the pressure plate and the wall of the second container opposite to the pressure plate, respectively. The spring is a tension spring.

2. The liquid level detection device according to claim 1, characterized in that: A second pressure plate is installed in the inner cavity of the first container. The diameter of the second pressure plate matches the inner diameter of the first container. The second pressure plate divides the inner cavity of the first container into two parts. One part of the inner cavity is connected to the air bag and is filled with air. The other part of the inner cavity is filled with liquid and is connected to the second container through a pipe. A flow meter is installed on the pipe. A limit rod is installed on one side of the second pressure plate. The limit rod is inserted into the connection port between the first container and the pipe.

3. The liquid level detection device according to claim 2, characterized in that: When a spring is installed in the second inner cavity, a hole is provided on the wall of the second container that forms the second inner cavity and is opposite to the pressure plate. It also includes a pressure plate limiting rod, one end of which is fixedly connected to the pressure plate, and the other end of which passes through the hole, with a spring sleeved on the outside of the pressure plate limiting rod.

4. The liquid level detection device according to claim 1, characterized in that: An air bag is fixed to the top of the first container and the air bag is connected to the inner cavity of the first container.

5. A washing machine, characterized in that: The liquid level detection device according to any one of claims 1-4 is fixed below the washing tub, and the air bag can contact the water at the bottom of the washing tub. A hole is provided at the bottom of the washing tub. The first container is fixedly connected to the bottom of the washing tub and seals the bottom of the hole. The air bag is located in the hole; the diameter of the hole is larger than the maximum diameter of the air bag.

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