JPH0240518A - Pressure detector for vacuum cleaner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure detector for a vacuum cleaner that can measure the pressure of a vacuum cleaner.

(Prior Art) As a pressure detector for detecting external pressure, there is a pressure detector disclosed in, for example, Japanese Patent Application Laid-open No. 130321/1982. were obtained through intensive research, and a vertical cross-sectional side view is shown in Fig. 5.

In the figure, 1 is a resistance circuit board on which a predetermined circuit pattern is formed by printing etc., and a pair of electrodes 2a, 2b are provided on the upper part.
is formed. Reference numeral 3 denotes a contact element that comes into contact with the electrode forming surface of the resistance circuit board 1, and is made of a conductive elastic material, and its tip is always in contact with the resistance circuit board 1. Reference numeral 4 denotes a plunger made of an insulating material, and is provided with four parts 4a for attaching the contactor 3 and a projection part 4b to which external pressure is applied. Reference numeral 5 denotes an exterior case that houses each of the above components.

The protrusion 4b of the plunger 4 can freely slide on the inner wall surface of the outer case 5.
When b is pressed, the plunger 4 moves downward in the figure, and the contact 3 is pressurized. At this time, the contact area of the contactor 3 with respect to the resistance circuit board 1 gradually changes as it changes from a non-pressure state to a pressurization state, forming an electrically parallel variable resistance circuit. Therefore, from the change in the resistance value measured at which contact point between the contactor 3 and the resistor circuit board 1, the plunger 4
It is possible to detect the pressure acting on the

[Problem to be solved by the invention]

The pressure detector configured as described above can accurately and stably detect a wide range of pressure from pressure 0 to a predetermined pressure, and has an excellent practical advantage. However, when used in a dusty place like a vacuum cleaner,
There is a risk that dust may enter between the plunger 4 and the outer case 5, resulting in poor durability, making it unsuitable for detecting the pressure of gases, etc., and having problems such as being unable to detect pressure differences between different external pressures. Ta.

This invention was made with attention to these problems, and is capable of detecting gas pressure, improving durability and reliability, and detecting pressure differences between different external pressures. The present invention provides a pressure detector with high accuracy and stability.

[Means to solve the problem]

A pressure detector for a vacuum cleaner according to the present invention includes a resistive circuit board having at least one pair of electrodes, and a contactor made of a conductive elastic body and in contact with the electrode-forming surface of the resistor circuit board. The resistor circuit board is held airtightly between a first diaphragm to which the resistor circuit board is attached, and a second diaphragm provided on the opposite side of the resistor circuit board to face the first diaphragm. 1st
and a first diaphragm on both ends of the outer case holding the second diaphragm. A through hole communicating with the second diaphragm is provided, and the through hole is passed through the first diaphragm. The pressure of the fluid acting on the second diaphragm is detected from the resistance value that changes due to the deformation of the contact.

Further, the pressure detector for a vacuum cleaner of the present invention is configured to detect the pressure acting on the first diaphragm to which the contactor is attached from the resistance value of the contactor, and detect the pressure acting on the second diaphragm from the resistance value of the contactor. It is also configured to detect from the resistance value of the contact, and furthermore, the difference between the pressure acting on the first diaphragm and the pressure acting on the second diaphragm is similarly detected from the resistance value of the contact. It is configured as follows.

[Effect]

In the vacuum cleaner pressure detector of the present invention, the resistance circuit board is held between the two diaphragms while maintaining airtightness, so there is a risk that dust etc. may enter the contact area between the resistance circuit board and the contact. Moreover, since through holes are provided on both sides of the outer case, pressure differences between different external pressures can be detected.

〔Example〕

FIG. 1 is a sectional view showing a first embodiment of the present invention. In the figure, 11 is a resistor circuit board having at least one pair of electrodes, on which a predetermined circuit pattern is formed by printing or the like, and through holes 11a .

flb is provided. 12 is this resistor circuit board 11
A contactor made of a conductive elastic material and in contact with the electrode-formed surface of the
3 is a first diaphragm to which this contactor 12 is attached;
14 is a second diaphragm provided on the opposite side of the resistor circuit board 11 to face the first diaphragm 13;
The resistance circuit board 11 is held between these two diaphragms 13 and 14 while maintaining airtightness. Reference numeral 15 denotes an exterior case holding the first and second diaphragms 13 and 14, each of which has a first diaphragm 15 on both ends. Through holes 15a and 15b communicating with the second diaphragms 13 and 14 are provided, and a through hole tsb communicating with the second diaphragm 14 is provided in the external connection portion 15c. Further, on the inner surface of the exterior case 15, first and second diaphragms 13 and 1 are provided.
Protrusions 15d and 15e are formed for fixing 4.

FIG. 2 is a cross-sectional view showing details of the resistor circuit board 11, in which a resistor 16 is provided by means such as printing, and the pair of electrodes 17a and 17b described above are also provided.

FIG. 3 shows the shape of the contact 12, which is formed into a conical shape from the tip 12a to the contact surface 12b, and the tip 12a is always in contact with the resistance circuit board 11. In addition, the outer peripheral portion is a first diaphragm 13.
The pressure-receiving portion of the diaphragm 13 is in close contact with a recess 12d therebetween.

The contactor 12 is molded from a conductive elastic body, and this conductive elastic body may be made of a known material obtained by adding a conductivity imparting agent such as carbon black to a polymeric elastic material such as rubber. things can be used. In addition, the shape is preferably such that when it comes into contact with the resistance circuit board 11, it is a point contact (or a line contact is also possible) when no pressure is applied, and the contact area increases as the pressure increases. It is shaped like a cone.

Next, the operation will be explained.

The pressure detector shown in FIG. 1 is configured to detect negative pressure, and is used with the external connection portion 15c connected to, for example, negative pressure piping. Then, when negative pressure acts on the pressure receiving part of the second diaphragm 14 through the through hole 15b, this negative pressure also acts on the first diaphragm 13 to which the contact 12 is attached, and the contact 12 is attached to the resistance circuit board 11. Pressed. At this time, the contact area of the contactor 12 with the resistance circuit board 11 gradually increases as the negative pressure increases. That is,
The contact area gradually changes from the point contact state when the pressure is 0 depending on the magnitude of the negative pressure, and an electrically parallel variable resistance circuit is formed as described above.

Therefore, the magnitude of the negative pressure can be detected from a change in the resistance value measured at the contact portion between the contactor 12 and the resistance circuit board 11.

Here, the first and second diaphragms 13 and 14 have a function of sealing against the resistance circuit board 11 and the contacts 12, and have a dust-proof structure 7. Therefore, there is no possibility that dust or the like will enter the contact portion between the resistance circuit board 11 and the contactor 12 from the outside during pressure detection. Therefore, pressure detection can always be performed accurately, stably, and with good responsiveness, resulting in improved durability and reliability.

Note that although the above example is for detecting negative pressure, if the external connection portion 15c is provided in the through hole 15a communicating with the first diaphragm 13, positive pressure can also be detected. Moreover, pressure detection can be performed not only for gas but also for liquid. At this time, unlike conventional methods, a plunger is not used, making it ideal for detecting pressure of gases, etc.

FIG. 4 is a sectional view showing a second embodiment of the invention. In this embodiment, the pressure difference between two different external pressures, that is, the difference between the pressure acting on the first diaphragm 13 and the pressure acting on the second diaphragm 14, is also detected from the resistance value of the contact 12. An external connection portion 15f is also provided for the through hole 15a. In this case, the side where the external pressure acts on the first diaphragm 13 to which the contactor 12 is attached is used as the high pressure (positive pressure) side, and the side where the external pressure acts on the second diaphragm 14 is used as the low pressure (negative pressure) side.

With this configuration, the pressure difference between the pressure acting on the first diaphragm 13 on the high pressure side and the pressure acting on the second diaphragm 14 on the low pressure side can be reduced by the contactor as in the above embodiment. It can be detected from 12 resistance values. At that time, the resistance circuit board 11 has a through hole 11a,
flb is provided to keep the air pressure in the space 18 sandwiched between the two diaphragms 13 and 14 constant, making it possible to detect changes in reduced pressure and pressure differences.

(Effects of the Invention) As explained above, according to the present invention, a resistor circuit board is held between two diaphragms while maintaining airtightness,
In addition, through holes are provided on both sides of the exterior case that communicate with the diaphragms, and the pressure acting on each diaphragm is detected from the resistance value of the contact that deforms when it comes into contact with the resistor circuit board, so it is possible to detect the resistor circuit board from the outside. There is no risk of dust entering the contact area of the contactor, which improves durability and reliability. It also has the effect of being able to detect the pressure difference between two different external pressures, and with high accuracy and stability. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the first embodiment of the invention, FIG. 2 is a sectional view showing details of the resistor circuit board shown in FIG. 1, and FIG. 3 is a sectional view showing the shape of the contact shown in FIG. 1. , FIG. 4 is a sectional view showing a second embodiment of the present invention, and FIG. 5 is a longitudinal sectional side view showing a conventional pressure detector. I --- Resistance circuit board 2 --- One contact 3 --- First diaphragm 4 --- Second diaphragm 5 --- Exterior case b --- Through hole b --------A pair of electrodes

Claims (4)

[Claims] (1) a resistive circuit board having at least one pair of electrodes;
A first contactor is provided with a contact made of a conductive elastic material and is in contact with the electrode forming surface of the resistance circuit board.
and a second diaphragm provided on the opposite side of the resistor circuit board to face the first diaphragm. Through holes communicating with the first and second diaphragms are provided at both ends of the exterior case holding the diaphragm, and the pressure acting on the diaphragm through the through holes is adjusted to a resistance value that changes with deformation of the contact. A pressure detector for a vacuum cleaner characterized by detecting pressure from (2) The pressure detector for a vacuum cleaner according to claim 1, wherein the pressure acting on the first diaphragm to which the contactor is attached is detected from the resistance value of the contactor. (3) The pressure detector for a vacuum cleaner according to claim 1, wherein the pressure acting on the second diaphragm is detected from the resistance value of the contact. (4) The pressure detector for a vacuum cleaner according to claim 1, wherein the difference between the pressure acting on the first diaphragm and the pressure acting on the second diaphragm is detected from the resistance value of the contact.