JPS5831852B2 - pressure sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure sensor that converts a fluid pressure change into a mechanical displacement, and further extracts this mechanical displacement as an electrical resistance change using a resistor.

Conventionally, pressure sensors convert fluid pressure changes into mechanical displacement, and then increase this mechanical displacement as changes in electrical quantity. They used utensils, etc.

When a differential transformer is used to convert this mechanical displacement into a change in electrical quantity, the movable core of the differential transformer is connected to a pressure conversion member such as a diaphragm that converts pressure changes into mechanical displacement. By moving this movable iron core, the voltage obtained on the secondary side of the differential transformer was changed.

However, it has the disadvantage that it is structurally very difficult to obtain desired characteristics of the change in electrical quantity with respect to pressure change.

Additionally, when a variable resistor is used to convert mechanical displacement into a change in electrical quantity, the slider of the variable resistor is connected to the pressure conversion member that converts pressure changes into mechanical displacement. The resistance value of the variable resistor was changed by the movement of this slider.

In this case, by changing the shape of the resistor of a variable resistor, the change characteristics of the amount of electricity with respect to pressure changes can be arbitrarily changed over a wide range, such as obtaining the desired characteristics of the change characteristics of the amount of electricity with respect to pressure changes. They are not very suitable and lack practicality, especially those that use wire-wound resistance as the resistor.
Adjustments were made by changing the winding of the wire-wound resistor, which was extremely time-consuming.

The present invention has been made in view of such conventional problems, and will be described below with reference to the drawings of FIGS. 1 to 4 showing one embodiment of the present invention.

In the figure, reference numeral 1 denotes a cylindrical housing with only one end open, and a disc-shaped connecting housing 2 connects the peripheral edge of the housing 1 to the housing 1 so as to close the opening of the housing 1. It is attached by caulking the periphery of the opening.

This connecting housing 2 is provided with a tube portion 3 having a through hole 3a, and this tube portion 3 is attached to a location where pressure to be detected is generated.

Reference numeral 4 denotes a diaphragm of a pressure conversion member that converts pressure changes into mechanical displacement, and the peripheral edge of this diaphragm 4 is attached to the opening of the housing 1 together with the connecting housing 2 so as to close this opening, The connecting housing 2 forms a space 5 that communicates with a location where pressure to be detected is generated through the through hole 3a of the connecting housing 2.

Reference numeral 6 denotes a pipe connected to the diaphragm 4 so as to be able to transmit mechanical displacement by bringing one end surface into contact with the substantially central part of the diaphragm 4.
By press-fitting it into the hole of the cylindrical metal fitting 7 fixed in the recess 1a of the housing 1, it is slidably fitted into the shaft body 8 fixed to the housing 1, and one end is connected to the flange 6a of the vibro, and the other end is connected to the metal fitting 7.
The diaphragm 4 is compressed by the compression spring 9 in contact with the diaphragm 4.
biased in the direction.

Here, the vibro and the shaft 8 constitute a transmission member that performs mechanical movement together with the diaphragm 4, which is a pressure converting member, and the shaft 8 is press-fitted into the hole of the metal fitting γ, and its Recess 1a where metal fitting 7 is provided in housing 1
Since the shaft body 8 is fixed to the casing 1 by being fixed to the casing 1, the shaft body 8 can be firmly fixed to the casing 1 even when the wall thickness of the casing 1 is thin.

Reference numeral 10 denotes a support ring whose one end is fixed to the inner wall surface of the housing 1 via a prismatic spacer 11 with a bolt 12 and a nut 13, and this support ring 10 is provided with a gap 10a in which the transmission member is located. Further, a screw hole 10b is provided at the other end of the support ring 10, and an adjustment screw 15 rotatably supported on the housing 1 by a stopper 14 is screwed into the screw hole 10b. supporting the ends.

Reference numeral 16 denotes a triangular prism-shaped resistor added to the support ring 10 so as to be located above the gap 10a of the support ring 10, and this resistor 16 is constructed by winding a wire around a triangular prism-shaped base.

Furthermore, guide grooves 16a are provided at both ends of the resistor 16.

Reference numeral 17 denotes a contact member having a linear contact piece 18 with a rectangular cross section that contacts the resistor 16 in an inclined and slidable manner, and this contact member 17 includes a metal plate 19 on which the contact piece 18 is disposed; It is constituted by an L-shaped plate spring 20 that urges this metal plate 19 in the direction of the resistor 16, and this contact body 1
7 connects the plate spring 20 to the flange 6a of the vibro and the nut 2.
1 and the U-shaped anti-rotation spring 22 is clamped through one end thereof, thereby being connected to the vibro.

Further, the resistor 1 is provided at both ends of the upper part of the metal plate 19.
Projecting pieces 19a are provided so as to be slidably fitted into guide grooves provided at both ends of the holder 6.

Note that the contact piece 18 is formed on the end surface of the metal plate 19 by making an oblique U-shaped cut in the metal plate 19 and bending a part of the metal plate 19 at the cut. A contact piece 18 having a rectangular cross section and a linear shape is provided on the metal plate 19 and is inclined with respect to the metal plate 19 and has a longitudinal end surface located on the metal plate 19 .

Further, the contact piece 18 is in contact with the resistor 16 at an acute angle portion of the resistor 16 .

In addition, the rotation prevention spring that prevents the rotation of the contact body 1T is
One end is fixed to the vibro, and the other end is fixed together with the support ring 10 to a location where the support ring 10 is fixed to the inner wall surface of the housing 1 via a spacer 11.

According to the above configuration, when the pressure in the space 5, that is, the pressure to be measured increases, the diaphragm 4 is displaced in the direction of pushing up the vibro against the force of the compression spring 9 that urges the pipe 4 in the direction of the diaphragm 4. and push the vibro upward.

As a result, the contact body 1T moves upward, and the contact point between the resistor 16 and the contact piece 18 of the contact body 1T moves, changing the resistance.

In this way, the magnitude of the pressure applied to the diaphragm 4 can be measured and detected based on the change in resistance.

Next, the characteristics of electrical resistance change with respect to pressure change when the shape of the linear contact piece 18 is appropriately selected will be explained.

For example, if a downwardly curved arc-shaped contact piece 18 is used which contacts the resistor 16 at an angle from left to right as shown in FIG. The characteristics are as shown by curve a in FIG. 6, and when using a straight contact piece 18 that contacts the resistor 16 from left to right at an angle as shown in FIG. The characteristic of electrical resistance change is as shown in the straight line in Fig. 6, and as shown in Fig. 5C, the resistor 16 moves from left to right.
When an upwardly curved arc-shaped contact piece 18 is used, which is in contact with an inclined surface, the characteristic of electrical resistance change with respect to pressure change is as shown by curve C in FIG.

That is, by arbitrarily changing the shape of the linear contact piece 18, it is possible to obtain a desired characteristic of electrical resistance change with respect to pressure change, and since the shape of the linear contact piece 18 is changed, it is very time-consuming. It is practical as it allows the characteristics to be easily changed over a wide range without requiring additional pressure sensors, and furthermore, because the structure is simple, the pressure sensor itself is also small and lightweight (it can be rubbed).

In addition, in this embodiment, the resistor 16 is connected by the adjusting screw 15.
Since it supports the other end of the support ring 10 with the
By operating this adjustment screw 15 to move the other end of the support ring 10 up and down, the relative contact position between the resistor 16 and the contact piece 18 can be changed, and the change in electrical resistance in response to a change in pressure can be changed. Fine adjustments can be made.

Moreover, since the resistor 16 is shaped like a triangular prism and is brought into contact with the contact piece 18 at this acute angle portion, it is possible to reduce errors in the resistance value at the contact position.

Furthermore, by changing the spring constant of the compression spring 9 that urges the vibro in the direction of the diaphragm 4, the detected pressure value at which the diaphragm 4 is displaced can be changed.

Furthermore, the contact piece 18 disposed on the metal plate 19 and the resistor 1
6 means that the metal plate 19 is biased toward the resistor 16 by the L-shaped plate spring 20, so there is no possibility of contact failure, and the protruding piece 19a provided on the metal plate 19 and the resistor By fitting into the guide groove 16a provided in the body 16, the contact pressure between the contact piece 18 and the resistor 16 does not change depending on the contact position, and can always be brought into contact with a constant pressure.

It goes without saying that the same effect as described above can be obtained even if the resistor 16 is provided with a protruding piece and the metal plate 19 is provided with a guide groove.

Further, in the above embodiment, the contact piece 18 is provided on the metal plate 19 by making a U-shaped cut in the metal plate 19 and bending it at the cut, but the contact piece 18 is not limited to this. , even if the contact piece 18 is provided by extruding a part of the metal plate 19, as shown in FIG.
Furthermore, as shown in FIGS. 8 and 9, the contact piece 18 may be provided by joining a round bar-shaped wire rod or a square bar-shaped wire rod to the metal plate 19.

Similarly, the contact body 17 is not limited to that of this embodiment, and may be constructed by bending a round rod-like rigid wire into a predetermined shape as shown in FIGS. 10a and 10b. Furthermore, the resistor 16 may be fixed to the vibrocc and the resistor 16 may be slid.

Furthermore, in addition to changing the shape of the linear contact piece 18,
At the same time, it is possible to tilt the resistor 16 and support it, or change the shape of the resistor 16 so that the width changes in the longitudinal direction as shown in FIG. By configuring the resistor 16 to change, the characteristics of electrical resistance change with respect to pressure change can be changed over a wider range than when only changing the shape of the contact piece 18.

The pressure sensor of this embodiment works under positive pressure, but as shown in FIG. 12, instead of the diaphragm 4, a bellows 23 filled with gas at a constant pressure (including vacuum) is used as a pressure converting member.
If used, it can also be used as a pressure sensor that operates under negative pressure.

As described above, the pressure sensor of the present invention includes a pressure conversion member that converts a pressure change into a mechanical displacement, a resistor, and a linear contact piece that slidably contacts the resistor at an angle. a contact body, one of the resistor and the contact body is fixed, and the other is slid by a transmission member that performs mechanical displacement together with the pressure conversion member, and the mechanical displacement of the pressure conversion member is controlled. By changing the shape of the linear contact piece arbitrarily, it is possible to obtain the characteristics of the electrical resistance change in response to the desired pressure change. This is an excellent device in that the characteristics can be changed over a wide range very easily without any effort, and furthermore, the pressure sensor itself can be made smaller and lighter.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the internal structure of a pressure sensor according to an embodiment of the present invention, Fig. 2 is a plan view of the sensor as seen inside after disassembling it, and Fig. 3a shows the main parts of the sensor. Exterior perspective view,
Fig. 3 is a sectional view thereof, Fig. 4 is an external perspective view of the main parts of the sensor, Fig. 5 a''-c is an explanatory diagram showing an example of the shape of the main parts of the eye sensor, and Fig. 6 The figure is a characteristic diagram of electrical resistance change with respect to pressure change corresponding to the example of Fig. 5 a"'-c,
7 to 9 are sectional views showing other embodiments of the main parts of the same sensor shown in FIGS. 3a and 3b, and FIG. 10a is sectional views shown in FIG.
10 is a side view thereof, and FIG. 11 is a plan view showing another embodiment of the essential parts of the sensor shown in FIG. FIG. 12 is a sectional view showing the internal structure of a pressure sensor according to another embodiment of the present invention. 1...Housing, 1a...Recess, 4...
...Diaphragm (pressure conversion member), 6...
Pipe, 7...Metal fitting, 8...Shaft, 1
5...Adjustment screw, 16...Resistor,
17...Contact body, 18...Contact piece, 1
9...Metal plate, 19a...Protruding piece, 2
0...Plate spring, 23...Bellows (pressure conversion member).

Claims (1)

[Claims] 1. A pressure conversion member that converts pressure changes into mechanical displacement;
It comprises a resistor and a contact body having a linear contact piece that is slidably in contact with the resistor, and one of the resistor and the contact body is fixed, and the other is fixed. A pressure sensor, characterized in that it is slid by a transmission member that performs mechanical movement together with the pressure conversion member, and converts mechanical displacement of the pressure conversion member into an electrical resistance change. 2. The pressure sensor according to claim 1, wherein the contact body is constituted by a metal plate provided with a contact piece and a leaf spring that urges the metal plate toward the resistor. 3. The pressure sensor according to claim 2, wherein the contact piece is constructed by making a U-shaped cut in the metal plate and bending a part of the metal plate at the cut. 4. The pressure sensor according to claim 2, wherein the contact piece is formed by extrusion molding a tab portion of a metal plate. 5. The pressure sensor according to claim 1, wherein the contact body is constructed by bending a rigid metal rod into a predetermined shape. 6. Claim 1, characterized in that a guide groove is provided at both ends of either the resistor or the contact body, and a protruding piece that slidably fits into the guide groove is provided on the other side. Pressure sensor as described. T. The pressure sensor according to claim 1, wherein the relative contact position between the resistor and the contact piece of the contact body can be adjusted by an adjustment screw. 8. The pressure sensor according to claim 1, wherein the resistor has a triangular prism shape, and its acute angle portion contacts the contact piece of the contact body. 9. The pressure sensor according to claim 1, wherein the resistor is configured such that the resistance value of the resistor changes non-uniformly as the contact body moves over the resistor in the longitudinal direction. . 10 Claims characterized in that the transmission member is constituted by a pipe connected to the pressure conversion member so as to be able to transmit mechanical displacement, and a shaft fixed to a casing into which the pipe is slidably fitted. The pressure sensor according to item 1. 11. Claim 10, characterized in that the shaft body is fixed to the casing by press-fitting the shaft body into a hole of a cylindrical metal fitting and fixing this metal fitting to a recess provided in the casing.
Pressure sensor described in section.