JP7847399B2 - Water level detection device - Google Patents

Description

This invention relates to a water level detection device.

A liquid level detection device is known that includes a float with a magnet and a group of magnetically sensitive switches. Such a device detects the liquid level based on the change in the combination of detection states of the magnetically sensitive switches as the float displaces. The liquid level detection device described in Patent Document 1, in addition to the conventional configuration, passes current through a composite resistor and detects the liquid level based on the amount of current in the composite resistor. As a result, it eliminates the dead zone when the liquid level drops and simplifies the circuit.

Patent No. 3533457

However, even with conventional liquid level detection devices and the liquid level detection device described in Patent Document 1, detecting malfunctions in the magnetically sensitive switch group remains difficult.

The object of this invention is to provide a water level detection device capable of determining malfunctions in a magnetic sensor element used to detect water level.

According to one aspect of the present invention, the water level detection device comprises a float, a plurality of magnetic sensor elements, and a malfunction detection unit. The float has a magnet and moves up and down in the water depth direction in response to fluctuations in the water level. The plurality of magnetic sensor elements are arranged in a row in the water depth direction and detect the magnetism of the magnet. The malfunction detection unit determines a malfunction in the plurality of magnetic sensor elements based on the detection results of each of the plurality of magnetic sensor elements.

According to the water level detection device of the present invention, it is possible to determine a malfunction in the magnetic sensor element that detects the water level.

This is an external view of a humidifier equipped with a water level detection device according to this embodiment. This figure shows the cross-sectional structure of the tray of the humidifier shown in Figure 1. This figure shows a cross-sectional view of the water level detection device. This is a block diagram of the water level detection device. This diagram shows the relationship between the ON/OFF state of the magnetic sensor element and the water level. This diagram illustrates how to detect a malfunction where one of the magnetic sensor elements is constantly ON. This diagram illustrates how to determine a malfunction when more than a predetermined number of magnetic sensor elements are turned ON consecutively. This diagram illustrates how to detect a malfunction in which one of the magnetic sensor elements is permanently OFF.

The embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and detailed descriptions will not be repeated.

The water level detection device 200 according to this embodiment is installed in equipment such as humidifiers and dehumidifiers, and detects the water level of the water stored inside the equipment. Furthermore, the water level detection device 200 can determine a malfunction of the magnetic sensor element 230, which will be described later, based on the detection results.

In this embodiment, a humidifier 100 equipped with a water level detection device 200 will be described as an example. However, the water level detection device 200 in this embodiment is not limited to a humidifier and can be installed in any device, such as a dehumidifier, to detect the liquid level.

The humidifier 100 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is an external view of the humidifier 100 equipped with the water level detection device 200 of this embodiment.

The humidifier 100 shown in Figure 1 has a rectangular parallelepiped casing 11. The upper surface 12 of the casing 11 is provided with an outlet 14 for humidified air 13, switches 15 for operating the humidifier 100, a water inlet 16 for supplying water W for humidification to the humidifier 100, and a display unit 19, which will be described later.

A tray 20 containing humidifying water W is housed in the lower part of the casing 11. Figure 2 shows the cross-sectional structure of the tray 20 of the humidifier 100 shown in Figure 1. The tray 20 is, for example, a rectangular parallelepiped with an open top. However, the tray 20 can have any shape as long as it fits within the casing 11.

A humidifying filter 17 is installed vertically inside the tray 20. The tray 20 has a pair of side walls 23, 23, each provided with a first protruding wall 21 and a second protruding wall 22. The first protruding wall 21 and the second protruding wall 22 block both end faces 17a of the humidifying filter 17 in contact, preventing leakage of the airflow passing through the humidifying filter 17.

Furthermore, by providing the second protruding wall 22, a storage space 30 is formed between the second protruding wall 22 and the side wall 23 of the tray 20. This storage space 30 is for a water level detection device 200 that detects the water level W stored in the tray 20.

Next, the water level detection device 200 in the humidifier 100 will be described with reference to Figure 3. Figure 3 is a cross-sectional view of the water level detection device 200. As shown in this figure, the water level detection device 200 comprises a float 201 and a magnetic sensor 210.

The float 201 has a magnet 202 and rises and falls in the direction of water depth in response to fluctuations in water level. The shape of the float 201 is, for example, a rectangular cross-section corresponding to the cross-sectional shape of the containment space 30, and is rectangular in front view. However, the shape of the float 201 can be any shape as long as it can be contained within the containment space 30.

The storage space 30 shown in Figure 3 is formed vertically, extending from the bottom of the tray 20 to the upper part of the tray 20, for example, directly below the position where the handle 24 is installed. A float 201 is housed in the storage space 30. The float 201 is configured to float on the water W stored in the tray 20. The float 201 rises and falls in response to fluctuations in the water level of the water W.

The weight of magnet 202 is such that the float 201 on which the magnet 202 is attached floats in water W. The size of magnet 202 and float 201 is determined by this condition. Furthermore, the magnetic force is determined by the size of magnet 202.

Furthermore, as shown in Figures 2 and 3, two ribs 40 may be formed on the side wall 23 and the second protruding wall 22 of the tray 20, spaced apart from each other. The tips of the ribs 40 can contact the float 201. As a result, surface contact between the float 201 and the side wall 23 and the second protruding wall 22 of the tray 20 is prevented. This allows the float 201 to smoothly move up and down within the storage space 30 in response to fluctuations in the water level W inside the tray 20.

Next, the water level detection device 200 will be described with reference to Figures 3 and 4. Figure 4 is a block diagram of the water level detection device 200. As shown in Figures 3 and 4, the water level detection device 200 has a magnetic sensor 210. The magnetic sensor 210 has a vertically elongated substrate 220, a plurality of magnetic sensor elements 230, and a transmitting unit 240.

Each of the multiple magnetic sensor elements 230 detects the magnetism of the magnet 202 on the float 201. The multiple magnetic sensor elements 230 are arranged in a line in the direction of water depth. In the example shown in Figures 3 and 4, nine magnetic sensor elements 230 are arranged vertically, with adjacent elements maintaining a constant vertical gap between them.

Any magnetic sensor element 230 can be used as long as it is capable of detecting the magnetism of the magnet 202 provided on the float 201. For example, a Hall IC (Integrated Circuit) can be used.

Figure 3 shows the positional relationship between the storage space 30 in the tray 20 pushed into the casing 11 and the magnetic sensor 210 provided on the casing 11 in relation to it. As shown in this figure, when the tray 20 is pushed into the casing 11, the magnetic sensor 210 is mounted on the inner surface 18 of the casing 11, which corresponds to the storage space 30.

Next, the spacing between the magnetic sensor elements 230 in the magnetic sensor 210 will be explained with reference to Figure 3. As shown in Figure 3, the spacing between vertically adjacent magnetic sensor elements 230 is such that the magnet 202 can be detected regardless of the vertical position of the float 201 equipped with the magnet 202.

Specifically, the spacing between the magnetic sensor elements 230 can be such that any of the vertically adjacent magnetic sensor elements 230 can detect the magnet 202. Alternatively, the spacing can be such that both of a pair of vertically adjacent magnetic sensor elements 230 can detect the magnet 202. This allows for the detection of the height of the magnet 202, i.e., the water level of the water W in the tray 20. This spacing is determined based on the magnetic force of the magnet 202, derived from its size as described above.

Figure 5 shows the relationship between the ON and OFF states of the magnetic sensor element 230 and the water level. In Figure 5, ● indicates that the magnetic sensor element 230 is in the ON state, and ○ indicates that the magnetic sensor element 230 is in the OFF state.

As shown in Figure 5, the water level detection device 200 of this embodiment detects the water level of the tray 20 based on the magnetic sensor elements 230 that have been turned ON when the magnet 202 is detected and one of the detected magnetic sensor elements 230 turns ON, or when a pair of vertically adjacent magnetic sensor elements 230 that have been detected turn ON. If all of the magnetic sensor elements 230 turn ON, it is determined that the tray 20 is not set in the humidifier 100. The transmitting unit 240 in Figure 4 then transmits the detection results of the magnetic sensor elements 230 to the receiving unit 250, which will be described later.

As shown in Figure 5, the water level detection device 200 of this embodiment detects the magnet 202 using one or two magnetic sensor elements 230 located at positions corresponding to the fluctuating water level. However, the water level detection device 200 of this embodiment is not limited to the above configuration; the magnet 202 may be detected by a single magnetic sensor element 230. Alternatively, if the spacing between the magnetic sensor elements 230 is narrow, it is possible to detect the magnet 202 with three magnetic sensor elements 230. In other words, the number of magnetic sensor elements 230 located at corresponding positions that detect the fluctuating water level can be arbitrarily determined by the spacing between the magnetic sensor elements 230, the magnetic force of the magnet 202, etc.

As described above, the magnetic sensor element 230 is used to detect the water level of the humidifier 100. Therefore, if a malfunction occurs in the magnetic sensor element 230, it may become impossible to accurately detect the water level of the humidifier 100. The water level detection device 200 detects the malfunction of the magnetic sensor element 230, allowing for early detection of the malfunction. As a result, the situation where the water level of the humidifier 100 cannot be accurately detected can be avoided. The following describes how the water level detection device 200 of this embodiment detects the malfunction of the magnetic sensor element 230.

As shown in Figure 4, the water level detection device 200 further includes a receiving unit 250 and an arithmetic processing unit 260. The receiving unit 250 receives the detection result of the magnetic sensor element 230 from the transmitting unit 240. The arithmetic processing unit 260 includes a processor such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). The arithmetic processing unit 260 controls each element of the water level detection device 200. The arithmetic processing unit 260 includes a malfunction determination unit 261 and a control unit 262.

The malfunction detection unit 261 determines the malfunction of the multiple magnetic sensor elements 230 based on the detection results of each of the multiple magnetic sensor elements 230. If a malfunction occurs in a magnetic sensor element 230, for example, the magnetic sensor element 230 may remain constantly ON or constantly OFF.

The malfunction detection unit 261, when three or more magnetic sensor elements 230 are arranged in a row, determines malfunctions in multiple magnetic sensor elements 230 based on the ON/OFF states of non-adjacent magnetic sensor elements 230.

First, let's explain an example where one of the magnetic sensor elements 230 remains constantly ON. Figure 6 illustrates how to determine if one of the magnetic sensor elements 230 is constantly ON.

The malfunction detection unit 261 determines that at least one of the magnetic sensor elements 230, which are arranged in a row of three or more, has a malfunction if at least one of them is ON and a non-adjacent magnetic sensor element 230 is also ON.

For example, in Figure 6, the magnetic sensor element 230-5 is initially ON. If the water level in tray 20 is decreasing and the actual water level is within the detection range of the magnetic sensor element 230-3, then in addition to magnetic sensor element 230-5, magnetic sensor element 230-3 also turns ON. In other words, in addition to magnetic sensor element 230-5, magnetic sensor element 230-3, which is not adjacent to magnetic sensor element 230-5, also turns ON. In this case, the malfunction detection unit 261 determines that there is a malfunction in magnetic sensor element 230-5.

Furthermore, even if none of the magnetic sensor elements 230 are constantly ON, the two magnetic sensor elements 230-3 and 230-5, which are positioned above and below the OFF magnetic sensor element 230-4, may become ON. In this case, it can be determined that there is a malfunction in one of the ON magnetic sensor elements 230.

Furthermore, the malfunction detection unit 261 determines that there is a malfunction in the magnetic sensor elements 230 that have been turned ON consecutively if more than a predetermined number of the magnetic sensor elements 230 arranged in a row have been turned ON. Here, "determined number" includes the maximum number of magnetic sensor elements 230 that turn ON when the magnetism of the magnet 202 is detected. For example, in this embodiment, the maximum number of magnetic sensor elements 230 that turn ON when the magnetism of the magnet 202 is detected is two.

Figure 7 illustrates the determination of a malfunction when more than a predetermined number of magnetic sensor elements 230 are turned ON consecutively. For example, in Figure 7, magnetic sensor element 230-3 is initially ON. If the water level rises in this state, the next elements to turn ON, as is clear from Figure 5, are magnetic sensor elements 230-3 and 230-4. However, in Figure 7, three magnetic sensor elements 230-3 to 230-5 are ON, which is more than the predetermined number of two. In this case, the malfunction determination unit 261 determines that there is a malfunction in magnetic sensor elements 230-3 to 230-5, more specifically, in magnetic sensor element 230-5.

Next, we will explain an example where one of the magnetic sensor elements 230 is permanently OFF. Figure 8 illustrates how to determine the malfunction in which one of the magnetic sensor elements 230 is permanently OFF.

For example, if the water level rises and at least one of the multiple magnetic sensor elements 230 turns ON, and then a magnetic sensor element 230 that is not adjacent to the at least one magnetic sensor element 230 turns ON within a first predetermined time, the malfunction determination unit 261 determines that there is a malfunction in the magnetic sensor elements 230 between the at least one magnetic sensor element 230 and the magnetic sensor element 230 that turned ON.

Specifically, in Figure 8, when the water level is rising, magnetic sensor element 230-4 turns ON. Subsequently, when magnetic sensor element 230-6, which is not adjacent to magnetic sensor element 230-4, turns ON within the first predetermined time, the malfunction determination unit 261 determines that there is a malfunction in magnetic sensor element 230-5 between magnetic sensor element 230-4 and magnetic sensor element 230-6.

The reason for setting a "first predetermined time" here is as follows: For example, while the water level is within the detection range of magnetic sensor element 230-4, the tray 20 may be removed from the casing 11 of the humidifier 100, and water may be supplied directly to the tray 20. Afterward, when the tray 20 is set back into the casing 11, the water level in the tray 20 may have risen beyond the detection range of magnetic sensor element 230-5 and into the detection range of magnetic sensor element 230-6. In this case, magnetic sensor element 230-4 will turn ON, followed by magnetic sensor element 230-6, but this does not necessarily mean that magnetic sensor element 230-5 is malfunctioning.

Therefore, the time approximately required to remove tray 20 from casing 11, add water, and then reattach it to casing 11 is defined as the first predetermined time and used as a criterion for fault detection. If the time from when magnetic sensor element 230-4 turns ON until when magnetic sensor element 230-6 turns ON is shorter than the first predetermined time, it is determined that there is a fault in magnetic sensor element 230-5.

On the other hand, if the time between the activation of magnetic sensor element 230-4 and the activation of magnetic sensor element 230-6 is longer than the first predetermined time, it is determined that water supply should be performed with the tray 20 removed, and a malfunction in magnetic sensor element 230-5 is not detected.

Next, we will explain how to determine if the lowest magnetic sensor element 230-1 is constantly OFF. When the water level is falling, the malfunction determination unit 261 determines that there is a malfunction in the lowest magnetic sensor element 230-1 if the lowest magnetic sensor element 230-1 does not turn ON within a second predetermined time period after the magnetic sensor element 230-2, located one position above the lowest magnetic sensor element 230-1, turns ON.

Here, the "second predetermined time" includes the approximate time it takes for the water level to drop from one magnetic sensor element 230 to the magnetic sensor element 230 located one level below it. For example, if the humidifier 100 is operated continuously, the water in the tray 20 will be depleted in approximately 16 hours. In this embodiment, since there are nine magnetic sensor elements 230-1 to 230-9, it takes approximately 2 hours for the water level to drop from one magnetic sensor element 230 to the magnetic sensor element 230 located one level below it. Therefore, in this embodiment, the second predetermined time is set to 2 to 3 hours.

The malfunction detection unit 261 determines that there is a malfunction in the lowest magnetic sensor element 230-1 if the lowest magnetic sensor element 230-1 does not turn ON within a second predetermined time period of 2 to 3 hours after the magnetic sensor element 230-2, which is located one position above the lowest magnetic sensor element 230-1, turns ON on its own.

Next, we will explain how to determine if the uppermost magnetic sensor element 230-9 is constantly OFF. For example, if the water level is rising, and the rate of water level rise between the two magnetic sensor elements in front of the uppermost magnetic sensor element 230-9, namely magnetic sensor element 230-7 and magnetic sensor element 230-8, is determined to be faster than a predetermined rate, then if the uppermost magnetic sensor element 230-9 does not turn ON in this state, the malfunction determination unit 261 determines that there is a malfunction in the uppermost magnetic sensor element 230-9.

Here, "predetermined speed" includes the speed at which the water level rises when water is supplied to tray 20 vigorously and nonstop. If the speed of water level rise is faster than the predetermined speed, it is determined that water is being supplied vigorously and nonstop. In this case, the water level is unlikely to fall within the detection range of magnetic sensor element 230-8 and is likely to reach the detection range of the uppermost magnetic sensor element 230-9. If the uppermost magnetic sensor element 230-9 does not turn ON in this state, the malfunction determination unit 261 determines that there is a malfunction in the uppermost magnetic sensor element 230-9.

On the other hand, if the water level is rising, it may be determined that the rate of water level rise between the two magnetic sensor elements in front of the uppermost magnetic sensor element 230-9, namely magnetic sensor element 230-7 and magnetic sensor element 230-8, is slower than a predetermined rate. In this case, even if the uppermost magnetic sensor element 230-9 does not turn ON, the malfunction detection unit 261 does not determine that the uppermost magnetic sensor element 230-9 is malfunctioning. In other words, the malfunction detection unit 261 determines that the uppermost magnetic sensor element 230-9 is functioning normally.

If the water level rise rate between magnetic sensor element 230-7 and magnetic sensor element 230-8 is slower than a predetermined rate, the water supply rate is not fast, and the user is likely to supply water cautiously, stopping the water supply before reaching the uppermost magnetic sensor element 230-9, which is at the full water level. Therefore, the malfunction detection unit 261 does not determine that there is a malfunction in the uppermost magnetic sensor element 230-9, even if the uppermost magnetic sensor element 230-9 does not turn ON.

In this way, malfunctions in the magnetic sensor elements 230 can be easily determined based on the ON and OFF patterns of the multiple magnetic sensor elements 230. As a result, malfunctions in the magnetic sensor elements 230 can be detected early, preventing situations where the water level of the humidifier 100 cannot be accurately detected.

Furthermore, when a malfunction is detected in the magnetic sensor element 230, this fact may be indicated by the display unit 19 shown in Figure 1. Specifically, when the malfunction detection unit 261 determines that there is a malfunction in the magnetic sensor element 230, the control unit 262 causes the display unit 19 on the upper surface 12 of the casing 11 to indicate that a malfunction has been detected. This indication may be optical, such as the illumination or flashing of an LED (Light Emitting Diode). Alternatively, an acoustic indicator, such as a warning sound, may be used instead of the display unit 19. Other display methods are also possible, and the display method is arbitrary.

Furthermore, the display unit 19 may display the water level from the water supply level to the full level using multiple LEDs. In this case, the LEDs indicating the water level may also be used as LEDs for error notification. For example, the LEDs may light up when indicating the water level and blink when notifying an error. Alternatively, the LEDs may light up in a first display color when indicating the water level and in a second display color when notifying an error. Alternatively, an LED for error notification may be provided near the LEDs indicating the water level.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. The drawings schematically show each component for ease of understanding, and the thickness, length, number, spacing, etc., of each component shown may differ from the actual dimensions due to the limitations of drawing creation. Furthermore, the materials, shapes, dimensions, etc., of each component shown in the above embodiments are examples only and are not particularly limiting; various modifications are possible without substantially departing from the configuration of the present invention.

This invention provides a water level detection device and has industrial applicability.

200 Water level detection device 201 Float 202 Magnet 230 Magnetic sensor element 230-1 Lower magnetic sensor element 230-9 Uppermost magnetic sensor element 261 Malfunction detection unit

Claims (3)

A float equipped with a magnet that rises and falls in the direction of water depth in response to fluctuations in water level,
Multiple magnetic sensor elements are arranged in a row in the direction of the water depth and detect the magnetism of the magnet,
The system includes a malfunction determination unit that determines a malfunction in the plurality of magnetic sensor elements based on the detection results of each of the plurality of magnetic sensor elements,
The malfunction determination unit determines that there is a malfunction in the lowest magnetic sensor element when the water level is falling and the lowest magnetic sensor element does not turn ON within a second predetermined time after the magnetic sensor element located one position above the lowest magnetic sensor element turns ON, in a water level detection device. A float equipped with a magnet that rises and falls in the direction of water depth in response to fluctuations in water level,
Multiple magnetic sensor elements are arranged in a row in the direction of the water depth and detect the magnetism of the magnet,
The system includes a malfunction determination unit that determines a malfunction in the plurality of magnetic sensor elements based on the detection results of each of the plurality of magnetic sensor elements,
The malfunction determination unit determines that there is a malfunction in the uppermost magnetic sensor element when the water level is rising, the rate of water level rise between the two magnetic sensor elements in front of the uppermost magnetic sensor element is faster than a predetermined rate, and the uppermost magnetic sensor element does not turn ON. A float equipped with a magnet that rises and falls in the direction of water depth in response to fluctuations in water level,
Multiple magnetic sensor elements are arranged in a row in the direction of the water depth and detect the magnetism of the magnet,
The system includes a malfunction determination unit that determines a malfunction in the plurality of magnetic sensor elements based on the detection results of each of the plurality of magnetic sensor elements,
The malfunction detection unit determines that if the water level is rising and the rate of water level rise between the two magnetic sensor elements in front of the uppermost magnetic sensor element is slower than a predetermined rate, the uppermost magnetic sensor element does not turn ON, and the uppermost magnetic sensor element does not determine that there is a malfunction in the uppermost magnetic sensor element.