JP2754830B2 - Pressure sensor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor configured to convert a gas pressure change into an electric quantity and detect the change, for example, for detecting the clogging of a duct air conditioner. Things.

<Prior art and its problems> As a conventional pressure sensor of this type, for example,
As disclosed in Japanese Patent No. 86324, etc., a rubber diaphragm or diaphragm box (hereinafter referred to as a diaphragm or the like) is used as a pressure sensing element, and the displacement of the plunger interlocked with the displacement accompanying the pressure change of the diaphragm or the like. Is known via a differential transformer, or a change in the distance between a magnet attached to the diaphragm or the like and a Hall IC disposed opposite to the magnet.

However, in the conventional pressure sensor as described above,
Since the diaphragm and the like constituting the pressure sensing element are made of rubber, the detection accuracy is easily affected by a change in the surrounding environmental temperature. In particular, when the ambient temperature is low, the hardness of the rubber diaphragm and the like increases, and even when the same pressure change occurs, the displacement of the diaphragm and the like is different from that at normal temperature, and the pressure detection accuracy deteriorates. There was.

In addition, in order to reduce the influence of the detection accuracy due to the change in the surrounding environmental temperature as described above, it is conceivable to increase the pressure receiving area of the diaphragm or the like, but in this case, the shape of the diaphragm or the like becomes larger. Almost in proportion, the entire pressure sensor becomes large, and hardening of the diaphragm or the like at a low temperature is inevitable, so that the influence on the detection accuracy due to the temperature change cannot be fundamentally solved.

<Object of the Invention> The present invention has been made in view of the conventional problems as described above, and a pressure that can greatly reduce the influence on the detection accuracy due to a change in environmental temperature while keeping the whole compact. It is intended to provide a sensor.

<Structure and Effect of the Invention> A pressure sensor according to the present invention is made of a metal, which is disposed so as to partition the case into two pressure chambers and is displaced in accordance with a pressure difference between the two pressure chambers. A pressure sensing element composed of an electrodeposited bellows, a plunger interlocking with the displacement of the pressure sensing element, a magnet attached to the tip of the plunger, a hall element arranged opposite to the magnet, And a circuit for detecting a change in the facing distance to the magnet as an electric quantity.

According to the present invention, since the metal electrodeposition bellows is used as the pressure detecting element, the metal electrodeposition bellows and the metal electrodeposition bellows are changed with a change in the pressure difference between the two pressure chambers partitioned by the metal electrodeposition bellows. The plunger interlocked with this displaces, but the pressure-displacement characteristics at this time can be maintained almost constant regardless of the level of the surrounding environmental temperature, and the magnet attached to the tip of the plunger and the opposing magnet The accuracy of the entire sensor can be determined only by the temperature characteristic of the circuit unit that detects a change in distance from the Hall element to be measured as an electric quantity.

Thereby, the influence on the detection accuracy due to the change in the environmental temperature can be extremely reduced, and a pressure sensor with high detection accuracy can be obtained.

Also, therefore, compared to conventional rubber diaphragms, it becomes possible to use electrodeposited bellows having a smaller shape,
This has the effect that the entire sensor is easily made compact.

<Embodiment of the Invention> Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of the entire pressure sensor according to the present invention,
FIG. 2 is a plan view thereof, and FIG. 3 is a transverse sectional view taken along the line III-III of FIG. In these figures, 1A is a cylindrical resin case body having a flange portion 1a, 1B is a cylindrical resin upper cover having a flange portion 1b and one pressure port 2, and these case body 1A and upper cover A disc-shaped resin base 1C having a vent hole 1c is interposed between the flange 1a and the flange portion 1b, and a bolt / nut 3 is formed between the two flange portions 1a and 1b.
The case 1 for a sensor is configured by fixing the sensor case 1 through the.

Reference numeral 4 denotes a lower cover made of resin, which has another pressure port 5 communicating with the inside of the case body 1A, and is fixed to the lower surface of the case body 1A via screws 6. 7 is a terminal block,
The terminal 8 is mounted on the upper surface of the upper cover 1B, and the terminal 8 protrudes into the upper cover 1B.

Reference numeral 9 denotes a metal electrodeposited bellows serving as a pressure sensing element, which is formed in a cylindrical shape with a bottom, and whose upper end flange portion 9a is engaged with a step formed near the opening end of the case main body 1A to form a case. By being housed and arranged in a concentric manner in the main body 1A, the inside of the case 1 is partitioned into a pressure chamber A communicating with one pressure port 2 and a pressure chamber B communicating with the other pressure port 5, and these two The pressure chambers A and B are configured to be displaced in the vertical direction in the drawing according to the pressure difference between the pressure chambers.

Reference numeral 10 denotes a plunger, which is fitted into a cylindrical portion 1d integrally protruding downward from the center of the base 1C, and has a lower end contacting the center of the bottom surface of the electrodeposited bellows 9. , In conjunction with the vertical displacement of the electrodeposition bellows 9.

Reference numeral 11 denotes a permanent magnet, and a yoke 12 is provided at the upper end of the plunger 10.
Mounted through. Reference numeral 13 denotes a Hall element, which is fixed to the center of the base 1C so as to face the permanent magnet 11. Reference numeral 14 denotes a printed circuit board, which is screwed to the upper surface of the base 1C, and constitutes a circuit unit for detecting a change in the opposing distance between the magnet 11 and the Hall element 13 as a voltage amount, via a lead wire 17. And is electrically connected to the terminal 8.

Reference numerals 15 and 16 denote auxiliary springs which balance the position of the electrodeposition bellows 9 when the pressure difference between the two pressure chambers A and B is zero. Table
18,19 are provided.

Next, the operation of the pressure sensor having the above configuration will be described.

When there is a difference between the pressures of the gas supplied from the pressure ports 2 and 5 to the pressure chambers A and B, the electrodeposition bellows 9 is vertically displaced. The plunger 10 moves up and down in conjunction with the displacement of the electrodeposition bellows 9, and the facing distance between the magnet 11 and the Hall element 13 changes.
Since the output voltage to the printed circuit board 14 fluctuates, the output voltage is led to a meter (not shown) through the lead wire 17 and the terminal 8 to detect the differential pressure between the pressure ports 2 and 5. it can.

Here, in the present invention, the influence of the surrounding environmental temperature is obtained by using a metal electrodeposition bellows 9 which maintains a substantially constant pressure-displacement characteristic regardless of a change in the surrounding environmental temperature as a pressure sensing element. And the predetermined pressure detection can always be performed with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of the entire pressure sensor according to the present invention, FIG. 2 is a plan view thereof, and FIG. 3 is a transverse sectional view taken along the line III-III of FIG. 1 ... case, 2,5 ... pressure port, 9 ... metal electrodeposited bellows, 10 ... plunger, 11 ... permanent magnet, 13 ...
Hall element, 14 …… Printed circuit board (circuit part), A, B ……
Pressure chamber.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01L 9/14 G01L 7/06

Claims (1)

(57) [Claims] 1. A pressure sensing element comprising a case, a metal electrodeposition bellows disposed so as to partition the inside of the case into two pressure chambers, and displaced in accordance with a pressure difference between the two pressure chambers. A plunger interlocked with the displacement of the pressure sensing element, a magnet attached to the tip of the plunger, a Hall element arranged opposite to the magnet, and a change in the opposing distance between the Hall element and the magnet are electrically measured. And a circuit unit for detecting the amount.