JPH0439632Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The invention is a pressure switch that can continuously detect changes in the detection target, and is particularly effective when continuously detecting the water level of the washing tub of a washing machine. can be used.

BACKGROUND ART Conventionally, a float switch has been used as a general detection means for detecting the water level in a washing tub, but when used in a washing machine, it has the drawback of clogging with lint, detergent, etc., and causing malfunctions. For this reason, as shown in FIG. 3, a pressure switch is generally used in which a diaphragm is actuated by air pressure and the diaphragm plate is raised against a spring force to close the contact.

Problems to be Solved by the Invention Conventional pressure switches can only detect water level at a single point because the contacts turn on and off at a constant air pressure, that is, at a constant water level. However, with the recent spread of microcomputers, fine-grained control is required, and for example, there is a need to continuously detect the water level in a washing tub instead of detecting it at a single point. Therefore, the present invention attempts to provide a pressure switch that continuously detects the object to be detected and is not affected by external disturbances.

Means for Solving the Problems The pressure switch according to the present invention includes an air hose connection portion through which air is sent in response to a change in a detection target, and a fixed frame to which a diaphragm operated by air pressure within the air hose is fixed, and the fixed frame A diaphragm plate and a permanent magnet with the diaphragm direction as the NS pole are installed inside, a ring-shaped closed magnetic path is installed outside the fixed frame, and a Hall element is installed in a part between the permanent magnet and the inner circumference of the ring-shaped closed magnetic path. The movement of the diaphragm due to air pressure, which changes in response to changes in the detection target such as the water level, is expressed as a continuous electrical signal change, which can be supplied to a microcomputer.

Effect The diaphragm is actuated by air pressure in response to changes in the detection target, and the position of the permanent magnet provided on the diaphragm plate changes, so the magnetic flux to the Hall element at the fixed position changes continuously. This change can be converted into voltage strength to detect a change in the object to be detected, and can be supplied to a microcomputer. Further, by providing a ring-shaped closed magnetic path outside the permanent magnet and the Hall element, it is possible to avoid the influence of leakage magnetic flux from the motor and earth's magnetism, which cause disturbances.

Example Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a pressure switch according to the present invention.

1 is a fixed frame, 2 is a molded frame having an air hose connection part, and 3 is a diaphragm that moves in response to air pressure from the air hose, and is attached to the inner wall of the fixed frame 1. 4 is a diaphragm plate that moves up and down within the fixed frame according to the movement of the diaphragm 3. 5 is a permanent magnet with NS poles in the diameter direction of the diaphragm,
The movement of the diaphragm 3 is detected via the diaphragm plate 4. 6 is a screw that adjusts the sensitivity of the diaphragm 3 to air pressure, and 7 is a spring provided between the adjusting screw 6 and the diaphragm plate. Reference numeral 8 denotes a ring-shaped closed magnetic path, which is composed of an iron ring inserted through the outer periphery of the fixed frame 1. Reference numeral 9 denotes a Hall element, which is provided in a part between the permanent magnet 5 and the inner circumference of the ring-shaped closed magnetic path 8. 10 is an annular frame in which the fixed frame 1 and the molding frame 2 are integrated.

The state of the magnetic flux before the diaphragm of the pressure switch configured as described above is activated is as shown in FIG. It flows through the Hall element 9 and returns to the S pole of the permanent magnet 5. Due to the magnetic flux to the Hall element 9 at this time, the Hall element 9 outputs a constant voltage. Next, when water is poured into the washing tub to be detected, the diaphragm is operated due to a change in air pressure depending on the water level, and the diaphragm plate 4 is raised. With this rise, the positional relationship between the ring-shaped closed magnetic path 8 and the permanent magnet 5 shifts, and the magnetic resistance of the magnetic path formed by the permanent magnet 5, the Hall element 9, and the ring-shaped closed magnetic path 8 increases. As the magnetic flux changes, the output voltage of the Hall element 9 changes, and changes in the water level can be continuously detected as changes in voltage.

In the above embodiment, an iron ring is used, but the ring is not limited to iron, and the same effect can be obtained with any magnetic ring.

Note that when using a Hall element, malfunctions due to earth's magnetism or magnetic flux leakage from the motor are a problem, but in the case of the present invention, a magnetic ring is provided outside the Hall element, resulting in the problem shown in Figure 2B. In this way, the disturbing magnetic flux that flows outward through the magnetic ring and causes problems can be almost completely shielded.

Effects of the invention A pressure switch with the above structure and function can continuously extract changes in water level as changes in voltage, and can detect changes in objects such as the water level in a washing machine in a continuous manner rather than by detecting a single point. The detailed information can be fed to a microcomputer, allowing advanced control functions to be performed. In addition, since detection is performed using a magnet, there is no risk of failure of the contact part because there are no contacts, and a highly reliable product that is not affected by disturbance magnetic fields due to the ring-shaped closed magnetic circuit can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the pressure switch according to the present invention, Fig. 2A is a plan view of the main part showing the state of distribution of magnetic flux of the permanent magnet in the product of the present invention, and Fig. 2B is a disturbing magnetic flux. FIG. 3 is a sectional view of a conventional pressure switch. 1... fixed frame, 2... forming frame, 3... diaphragm, 4... diaphragm plate, 5... permanent magnet,
8...Ring-shaped closed magnetic circuit, 9...Hall element.

Claims (1)

[Scope of utility model registration request] It is equipped with a molding frame having an air hose connection part through which air is sent in response to changes in the detection target, and a fixed frame in which a diaphragm operated by the air pressure in the air hose is fixed, and the diaphragm plate and its diametrical direction are mounted in the fixed frame. A pressure switch characterized in that a permanent magnet is provided as a pole, a ring-shaped closed magnetic path is provided on the outside of a fixed frame, and a Hall element is provided in a part between the permanent magnet and the inner circumference of the ring-shaped closed magnetic path.