JPH02120634A - Pressure sensor and water level detector - Google Patents

Abstract

PURPOSE:To enhance the humidity resistance and insulating resistance of a pressure sensor element by sealing the pressure receiving hole of a pressure- sensitive element by an insulating liquid. CONSTITUTION:An insulating liquid 15 is enclosed in the pressure receiving hole in contact with the pressure introducing port 2 under the diaphragm 6 of a pressure sensor 1 and seals the pressure receiving hole by surface tension because the diameter of the pressure introducing port 2 is about 1mmphi. By this method, even when steam or a conductive liquid enters the pressure introducing port 2, the dew condensation in the pressure receiving hole or the destruction of a pressure sensor element 5 is prevented and pressure can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a pressure sensor and a water level detection device using the pressure sensor.

(Prior Art) Conventionally, mechanical pressure sensors have often been used to measure water levels. This mechanical pressure sensor has been developed and put into practical use by improving its internal structure to provide linear characteristics with respect to water pressure.

The above mechanical pressure sensor will be explained using FIG. 10. For mechanical pressure sensor ■, large diaphragm 101. Diaphragm plate 102. Iron core 103° coil 1
04 etc. The diaphragm 101 is made of rubber, and the diaphragm plate 102 is made of plastic.

In the pressure sensor configured in this way, when pressure P is applied to the diaphragm 101 in the pressure sensor 100, the diaphragm 101 is deformed, and the diaphragm plate 102 is deformed.
is pushed up, and the change in inductance of the coil 104 is output due to the displacement of the iron core 103 to measure the water level.

This pressure sensor 100 has good insulation because the diaphragm 101 is made of rubber and the diaphragm plate 102 is made of plastic material.However, this pressure sensor 100- has a structure that is Since it is a mechanical type, there is a disadvantage that the sensor itself becomes large. Therefore, as an alternative to the above-mentioned mechanical pressure sensor 1, a water level detection device is constructed using a semiconductor pressure sensor. has been developed and put into practical use.

This semiconductor pressure sensor will be explained using FIG. In the figure, the semiconductor pressure sensor 110 is
A silicon pedestal 112 is provided in the envelope 111, and a silicon semiconductor crystal substrate which is the St pressure sensor element 113 is provided on the silicon pedestal 112. A part of this silicon semiconductor crystal substrate is a thin 8i pressure sensor diaphragm 114. It becomes.

A diffused resistor is formed on this 8i pressure sensor diaphragm 114 as a pressure sensitive element. Further, the semiconductor pressure sensor 110 is provided with a pressure introduction port 115 and an air hole 116. 117 is an envelope lid, and 118 is a pin.

In the semiconductor pressure sensor 110 configured in this way, pressure is applied to the pressure introduction port 115, and the pressure is applied to the pressure introduction port 115.
Through this, pressure is applied to the Si pressure sensor diaphragm 114. This pressure is transferred to the Si pressure sensor diaphragm 114.
Pressure is measured using the piezo effect of the diffusion resistor above. This semiconductor pressure sensor 110 is very small because it uses a semiconductor, and has good sensitivity because it uses a piezo effect.

However, when this semiconductor pressure sensor is used in a water level detection device, when the pressure medium contains water vapor or the medium itself is conductive, the pressure receiving part of the pressure sensor (Si pressure sensor diaphragm 114
) may condense or be exposed to a conductive substance, which may destroy the Si pressure sensitive element 113 itself, and may also cause electric shock to the human body.

(Problems to be Solved by the Invention) As described above, conventional pressure sensors and water level detection devices using pressure sensors cannot be used when the pressure medium contains water vapor or when the medium itself is conductive. If the pressure receiving part of the pressure sensor is exposed to dew condensation or conductive substances, the pressure sensor element itself may be destroyed, and there is also a risk of electric shock to the human body.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a pressure sensor and a water level detection device using the pressure sensor that are small and improve the moisture resistance and insulation resistance of the sensor element. do.

Another object of the present invention is to provide a pressure sensor having a structure that allows moisture resistance and insulation resistance of the pressure sensor to be simply imparted during the manufacturing process of the sensor application device, independently of the sensor manufacturing process. Another object of the present invention is to provide a water level detection device using a pressure sensor.

[Structure of the invention]

(Means for solving Section 4♂1) In order to achieve the above object, the pressure sensor of the present invention seals insulating liquid from the pressure receiving hole of the pressure sensing element, and the diaphragm of the pressure sensor is filled with this liquid. The sensing atmosphere is separated from the diaphragm by sealing. In addition, a water level detection device using a pressure sensor connects the pressure receiving hole of the pressure sensor and a water tank through a resin-made, usable thin tube, and connects the space in the thin tube created by the water supplied to the water tank. It is characterized by separating the diaphragm part and the water tank by sealing in an insulating liquid.

(Function) In the pressure sensor configured as described above, by filling the insulating liquid from the pressure receiving hole of the I"5 pressure element of the pressure sensor, the surface tension of the liquid causes the liquid to flow out from the pressure receiving space of the pressure sensor. The diaphragm part of the pressure sensor can be sealed without falling. Therefore, even if the pressure medium contains water vapor or the medium itself is conductive, there will be no condensation in the pressure receiving hole of the pressure sensor. Pressure can be measured without destroying the sensor element itself.In addition, in a water level detection device using a pressure sensor, an insulating Even if the pressure medium contains water vapor or the medium itself is conductive, it will prevent condensation from forming in the pressure receiving hole of the pressure sensor.
Water level can be measured without destroying the pressure sensor element itself. In addition, in the manufacturing process of pressure sensors,
Since the encapsulation work can be easily carried out during the manufacturing of the application device, it is possible to prevent moisture resistance and insulation resistance from deteriorating over time.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a sectional view showing an embodiment of the pressure sensor of the present invention.

In the figure, a pressure sensor 1 includes an envelope 3 having a pressure inlet 2 and a silicon pedestal 4.
A silicon semiconductor crystal substrate, which is the pressure sensor element 5, is provided above, and a part of this silicon semiconductor crystal substrate (
The pressure inlet 2 (above) is a diaphragm 6. The thickness of this diaphragm 6 is approximately 30 μm, and the lower part thereof serves as a pressure receiving hole.

Further, a diffused resistor 7 is formed on the diaphragm 6 as a pressure sensitive element. This diffused resistor 7 is formed on the diaphragm 6 of the pressure sensor element 5, as can be seen from the cross-sectional view of FIG. An 810□ film 8 is formed on the pressure sensor element 5 on which the diffused resistor 7 is formed so as to provide an open portion on the diffused resistor 7. A person 1 contact 9 is formed in the open portion on the diffused resistor 7, and the person 1 contact 9 and the pad 10 are connected by aluminum wiring. This pad 10 is connected to a pin 12 with a bonding wire 11.

Further, the envelope 3 of the semiconductor pressure sensor 1 is provided with an air hole 13 for removing air from the space created above the pressure sensor element 5 in order to take the difference between the measured pressure and the atmospheric pressure. . 14 is an envelope lid for isolating the pressure sensor element 5 from the outside. Further, the air hole 13 may be provided not in the envelope 3 but in the envelope lid 14.

An insulating liquid 15 is sealed in a pressure receiving hole in the lower part of the diaphragm 6 that is in contact with the pressure introduction port 2 . Since the diameter of the pressure inlet 2 of this insulating liquid 15 is approximately 1 mm,
The pressure receiving hole in contact with the pressure introduction port 2 at the bottom of the diaphragm 6 is sealed by surface tension.

The insulating liquid 15 is supplied with pressure from a pressure receiving hole in contact with the pressure inlet 2 at the lower part of the diaphragm 6, as shown in the cross-sectional view of a pressure sensor according to a modification of the embodiment of the present invention in FIG. It may be enclosed so as to cover up to the introduction port 2. In this case as well, since the diameter of the pressure introduction port 2 is approximately 1×, the insulating liquid 15 seals the pressure receiving hole due to surface tension. In the semiconductor pressure sensor 1 configured in this manner, pressure is applied to the pressure introduction port 2, and pressure is applied to the diaphragm 6 of the pressure sensor element 5 through the pressure introduction port 2. This pressure is measured using the piezo effect of the diffusion resistor 7 formed on the diaphragm 6.

Even if water vapor or conductive liquid can enter the pressure introduction port 2, the insulating liquid 15 is sealed in the space between the pressure receiving hole of the diaphragm 6 of the pressure sensor element 5 and the pressure introduction port 2. Pressure sensor element 5 using water vapor or conductive liquid
The pressure receiving hole can be prevented from condensation and destruction. In addition, effects on the human body such as electric shock can be prevented.

Therefore, the pressure received by the pressure receiving hole of the diaphragm 6 of the pressure sensor element 5 can be measured by using the piezo effect of the diffusion resistor 7 formed on the diaphragm 6 to measure the change in electrical resistance.
The measured signal is sent from the pad 10 through the bonding wire 11 to the pin 12, and from this pin 12 is sent to a control device (not shown) for control, thereby controlling the moisture resistance and insulation resistance of the sensor element 5. In addition, it is possible to perform control with high sensitivity.

Next, a water level detection device using the pressure sensor of the present invention will be explained.

FIG. 4 is a sectional view showing an embodiment of a water level detection device using the pressure sensor of the present invention.

The pressure inlet 21 of the pressure sensor shown in the figure and the water tank 22 are connected by an insulating and flexible thin tube 23 made of resin.
5 and the space inside the water tank 22 are communicated with each other. This thin tube 23
The air 24 in the space inside is cut off from the air in the atmosphere by water being supplied to the water tank 22, and the air remaining in the space in the thin tube 23 due to changes in the water level of the water 25 supplied to the water tank 22. 24 is compressed. Further, an insulating liquid 26 is sealed in the thin tube 23. An insulating liquid 26 in the M pipe 23 electrically isolates the water 25 supplied to the water tank 22 and the pressure receiving hole 35 of the pressure sensor 20, and also
The water vapor 27 generated from the pressure sensor 1 and the pressure receiving hole 30
Cut off the supply to the

The air 24 remaining in the space inside the thin tube 23 is removed from the water tank 2 described above.
The water 25 supplied to the pressure sensor 20 is compressed by a change in the water level, and the pressure change received by the pressure receiving hole 35 of the pressure sensor 20 is converted into an electric signal, and this electric signal is provided on the same circuit board 28 as the pressure sensor 20. The control circuit 29 detects the water level.

In addition, it is resinous and flexible! If the neutral liquid 26 in the It pipe 23 is closely connected to the pressure sensor and the pressure inlet 21 and the narrow tube 23, the insulating liquid 26 will not fall toward the water tank 22 due to surface tension. do not have.

Next, the operation of the water level detection device of the present invention having the above configuration will be described. When water 25 is supplied into the water tank 22, the water 25 flows into the thin tube 23 connected to the water tank 22.

As the water 25 flows in, the air between the insulating liquid 26 and the water 25 in the thin tube 23 becomes air containing water vapor 27 generated from the water 25.

However, the insulating liquid 2G provided in the thin tube 23 seals the air containing the water 25 and water vapor 27 from flowing into the pressure introduction port 21 of the pressure sensor 20. Moreover, even if the water level in the water tank 22 changes,
As described above, the insulating liquid 261 provided in the thin tube 23 seals off the water 25 and water vapor 27 from flowing into the pressure receiving holes 35 of the pressure sensors. When the air 24 remaining in the space in the thin tube 23 is compressed by a change in the water level of the water 25, the pressure sensor converts the change in pressure received by the pressure receiving hole 35 into an electrical signal, and converts this electrical signal into a pressure sensor. The water is sent to a control circuit 29 provided on the same circuit board 28 as the sensor 20, and this control circuit 29 detects the water level. Therefore, even when the pressure medium contains water vapor 27 or the medium itself is conductive, the water level can be adjusted without condensing the pressure receiving hole 35 of the pressure sensor B or destroying the pressure sensor cord. can be measured.

In addition, in this embodiment, as shown in the cross-sectional views of the modified examples of the water level detection device using the pressure sensor of the present invention in FIG. 5 and FIG. By providing the 0-shaped portion 30 or bending a part of the thin tube 23, which is similarly made of resin and flexible, into a loop shape 31ζ, and filling the 0-shaped portion 30 and the loop portion 31 with the insulating liquid 26. Even if the surface tension of the insulating liquid 26 becomes tight due to transportation and vibration of the main body of the water level detecting device, the insulating liquid 26 will not reach the water tank 22.
It will not fall in any direction. Furthermore, as shown in the cross-sectional view of a modified example of the water level detection device using the pressure sensor of the present invention in FIG. A 1■ line part 32 is provided in this 0 character part 30,
By making the length of this straight portion 32 longer than the moving distance due to the pressure of the insulating liquid 26 enclosed, the weight of the insulating liquid 26 itself when the insulating liquid 26 moves due to pressure can be reduced. It is possible to prevent loss of pressure applied to the pressure sensor due to 1. Water level can be detected more accurately.

Next, a case will be described in which the water level detection device using the pressure sensor of the present invention is used in a washing machine.

FIG. 8 is a sectional view showing an embodiment in which a water level detection device using a pressure sensor of the present invention is used in a washing machine.

In the figure, the washing machine main body 40 washes and rinses laundry.
A water tank 41 for dehydration, a rotating tank 42 provided in this water tank 41, and a motor 43 for rotating this rotating tank 42.
, a flexible resin thin tube 44 connected to the bottom of the water tank 41, and a pressure sensor 4 disposed at the other end of this thin tube 44.
5, a water supply valve (not shown), a drain valve 46, etc. An insulating liquid 47 is sealed in the resinous and flexible thin W 44 . The other end of the thin tube 44 is closely connected to a pressure receiving hole (not shown) of a pressure sensor 45,
The air 48 in the space inside the thin tube 44 is shut off from the air in the atmosphere, and the air 48 remaining in the space inside the thin tube 44 is compressed by changes in the water level of the water 49 supplied to the water tank 41. In addition, the insulating liquid 47 in the thin tube 44 causes the water tank 4 to
1. The supplied water 49 and the pressure receiving hole of the pressure sensor 45 are cut off, and the water vapor 50 generated from the water 49 and the pressure receiving hole of the pressure sensor 45 are cut off.

When the air 48 remaining in the space in the thin tube 44 is compressed due to a change in the water level of the water 49 supplied to the water tank 41,
Changes in the pressure received by the pressure receiving hole of the pressure sensor 45 are converted into an electrical signal, this electrical signal is sent from the pressure sensor 45 to a control circuit (not shown), and the water level of the water 49 in the water tank 41 is detected by this control circuit. It is configured as follows.

Next, the operation of the washing machine of the present invention with the above configuration will be explained using the operating characteristic diagram shown in FIG. 9 when the water level detection device using the pressure sensor of the present invention is used in the washing machine. To use this washing machine for the first time, turn on the power switch, select the water level (for example, high water level) according to the laundry load on the operation panel (not shown), put the laundry and detergent, and turn on the start switch. throw into. This action causes the control circuit to send a signal to the drain valve 46 and the water supply valve, open the closed water supply valve, close the drain valve 46, and supply water.

Water 49 is supplied into the water tank 41 by this water supply, and at the same time, a thin tube 44 made of resin and flexible is connected to the bottom of the water tank 41.
Water 49 also comes inside. When the air 48 remaining in the space in the thin tube 44 is compressed by the change in the water level of the water 49, the change in pressure received by the pressure receiving hole of the pressure sensor 45 is converted into an electric signal, and this electric signal is converted into an electric signal. sensor 45
When the control circuit reaches a preset water level (high water level in this case), it closes the water supply valve and at the same time rotates the motor 43 to rotate the rotary tank 42 and wash the water. Perform the process. This washing process lasts for a predetermined period of time, and when this washing process is completed, the motor 43 is stopped, the drain valve 46 is opened, and the water 49 in the water tank 41 is drained. This draining step is also continued for a predetermined period of time, and when the draining step is completed, the water supply valve that had been closed is opened again, the drain valve 46 is closed, and water is supplied. This water supply fills water 49 in the water tank 41.
is supplied, and at the same time, water 49 also enters a resinous and flexible thin tube 44 connected to the bottom of the water tank 41. When the air 48 remaining in the space in the thin tube 44 is compressed by the change in the water level of the water 49, the change in pressure received by the pressure receiving hole of the pressure sensor 45 is converted into an electric signal, and this electric signal is converted into an electric signal. from the sensor 45 to a control circuit (not shown);
When the control circuit reaches a preset water level (high water level in this case), the water supply valve is closed and the motor 43 is simultaneously activated.
The rinsing process is performed by rotating the rotary tank 42 and rotating the rotary tank 42. This rinsing process lasts for a predetermined period of time, and when the rinsing process is completed, the motor 43 is stopped, the drain valve 46 is opened, and the water 49 in the water tank 41 is drained.

This draining step is also continued for a predetermined period of time, and when the draining step is completed, the above-mentioned rinsing step is repeated two or three times to perform the dewatering step.

By operating in this way, water vapor 50 is added to the water 49.
Even if there is an insulating liquid 47 sealed in the thin tube 44, the pressure sensor 45 can be used without condensing the pressure receiving hole of the pressure sensor 45 or destroying the pressure sensor element. The water level of the water tank 41 can be measured accurately.

The present embodiment is not limited to this, and the thin tube 44 may be made of resin and flexible thin tube 44 with a U-shaped portion provided in a part thereof as in the previous embodiment, or similarly resinous and flexible thin tube 44. By bending a part of 44 into a loop shape and filling insulating liquid 47 in this U-shaped part and the loop part, the main body of the washing machine ■
Even if the surface tension of the insulating liquid 47 weakens due to transportation and vibration, the insulating liquid 47 can be prevented from falling toward the water tank 41. In addition, a U-shaped part is provided in a part of the resinous and flexible thin 144, and a straight part is provided in this U-shaped part, and the length of this straight part moves with the pressure of the insulating liquid 47 enclosed. By making it longer than the distance, it is possible to prevent loss in the pressure applied to the pressure sensor 45 due to the weight of the insulating liquid 47 itself when the insulating liquid 47 moves due to pressure, Water level can be detected more accurately.

〔Effect of the invention〕

According to the present invention, by sealing the pressure receiving hole of the pressure sensing element of the pressure sensor with an insulating liquid, even when the pressure medium contains water vapor or the medium itself is conductive, , pressure can be measured without condensing the pressure receiving hole of the pressure sensor or destroying the pressure sensor element itself. In addition, in a water level detection device using a pressure sensor, an insulating liquid is filled in the space in the thin tube connected to the pressure receiving hole of the pressure sensing element of the pressure sensor, so that water vapor is not contained in the pressure medium. Even when the medium itself is conductive, the water level can be measured without condensing the pressure receiving hole of the pressure sensor or destroying the pressure sensor element itself.

In addition, since the pressure receiving hole is sealed with liquid, the liquid can move freely within the space in response to pressure changes, and is reliable without being lost during pressure changes. This has the effect of enabling highly accurate pressure detection.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the pressure sensor of the present invention;
FIG. 2 is a sectional view showing the configuration of a pressure sensor element according to an embodiment of the present invention, FIG. 3 is a sectional view of a pressure sensor according to a modification of the embodiment of the present invention, and FIG. 4 is a sectional view showing the configuration of a pressure sensor element according to an embodiment of the present invention. A sectional view showing an example of a water level detection device using a pressure sensor, FIG.
6 and 7 are cross-sectional views of modified examples of the water level detection device using the pressure sensor of the present invention, and FIG. 8 shows an embodiment in which the water level detection device using the pressure sensor of the present invention is used in a washing machine. FIG. 9 is an operational characteristic diagram when the water level detection device using the pressure sensor of the present invention is used in a washing machine, FIG. 10 is a cross-sectional view of a conventional mechanical pressure sensor, and FIG. 11 is a diagram of the conventional mechanical pressure sensor. FIG. 2 is a cross-sectional view of a semiconductor pressure sensor. 1, 20.45... Pressure sensor 2.21... Pressure receiving hole 5... Sensor element 6... Diaphragm 7... Diffusion resistor 15, 26.47... Insulating liquid 22, 41... Water tanks 23, 44... Thin tubes 24, 48... Air tank... Washing machine body No. l Figure Agent Patent attorney Noriyuki Chika Yudo Hirodai Uji 2 Figure rod Figure 26 + ε sword τ Shibu No. 40 Shi4 J11 stop

Claims (3)

[Claims] (1) In a pressure sensor that has a pressure-sensitive element and converts changes in applied pressure from the front or back surface of the pressure-sensitive element into an electrical signal, the pressure-receiving hole of the pressure-sensitive element is sealed with an insulating liquid. A pressure sensor characterized by: (2) In a pressure sensor that has a pressure-sensitive element and converts changes in applied pressure from the front or back surface of the pressure-sensitive element into an electrical signal, an insulating liquid is filled from the pressure inlet of the pressure-sensitive element. A pressure sensor, characterized in that a pressure receiving hole of the pressure sensor is sealed. (3) The pressure receiving hole of the pressure sensor and a water tank are connected by a thin tube, and the water supplied to the water tank blocks the air in the space inside the thin tube from the air in the atmosphere, and the water level supplied to the water tank is Compressing the air remaining in the space in the capillary by a change in
In a water level detection device using a pressure sensor that converts pressure changes at this time into electrical signals, a flexible thin tube made of resin is used as the thin tube, and an insulating liquid is sealed in the space inside the thin tube. A water level detection device characterized by: