JPS59137835A - Diaphragm type pressure sensor - Google Patents

Abstract

PURPOSE:To prevent breakdown due to excessive pressure difference, by opening a container by the pressure difference when the pressure difference between pressure media, which are contacted with both surfaces of the diaphragm of a pellet, exceeds a specified value, thereby communicating the inside and the outside of the container. CONSTITUTION:For example, a first pressure medium through a first through hole 14 is a free atmosphere, and a second pressure medium through a pressure conducting pipe 17 is a pressurized atmosphere, which is the object to be measured. In correspondence with the pressure difference between the first and second pressure madia, a diaphragm 21 of a pellet 20 is curved downward. The amount of change is converted to the amount of electricity by a piezo electric resistor part 23, and the result is taken out of lead pins 13. When said pressure difference exceeds a specified value, a thin film 16 is broken, and the inside and the outside of a container 10 are communicated.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to a diaphragm pressure sensor.

(b) Conventional technology In this type of sensor, approximately 20μ made of silicon, etc.
The diaphragm is deformed by the differential pressure of each pressure medium that is in contact with both sides of the diaphragm, and the amount of deformation is converted into an electrical quantity by a piezoresistive section provided on the diaphragm to detect pressure. Therefore, if the differential pressure becomes too large, the diaphragm will be destroyed, but with conventional sensors,
No consideration has been given to destruction caused by such excessive differential pressure.

(c) Purpose of the Invention The present invention attempts to stop further increase in the differential pressure before the diaphragm breaks down.

(D) Structure of the Invention The structural feature of the present invention is that a diaphragm-type pressure sensor pellet is housed in a container, and when the pressure difference between each pressure medium in contact with both surfaces of the diaphragm of the pellet becomes a predetermined value or more, The container is provided with a differential pressure release means that is opened by pressure to establish communication between the inside and outside of the container.

(e) Example As shown in the drawing, in the sensor of this example, a pressure sensor pellet (20) is housed in a container (10).

The container (10) includes a header (11) and a cap (12) hermetically sealed thereto.
11) passes through and holds the lead pins (13) in an airtight manner, and has a first through hole (14) at the center and a second through hole (15) at the periphery. The presence of the second through hole (15) is in accordance with the invention, the outside of which is closed with an aluminum thin film (16) fixed to the header (11).

The pressure tube (12) is provided with a pressure pipe (17) through which the sensor and the pressure source can be connected.

The pressure sensor pellet (20) is made of silicon and includes an ultra-thin diaphragm (21) and a thick annular base (22) surrounding it.The diaphragm (21) is equipped with piezoresistors (23) (23)...・It is a well-known thing with.

The electrode of the pellet (20) is connected to the ρ pin (13) by a lead wire (24). The pressure cell and sapelet (20) are firmly fixed on the header (11) via the annular intermediate base (25) made of silicon, and the first part of the header (11)
Cover the through hole (14). Pellet (20) and intermediate base (2
5) Furthermore, the intermediate base and the hem (11) are each hermetically sealed with an adhesive, so that the first pressure medium passing through the first through hole (14) of the header (11) is in contact with the pellet (20). contacting only the back surface, while the second through the pressure pipe (17)
The pressure medium will contact only the surface of the pellet (20).

Therefore, in the above sensor, for example, the first through hole (14)
If the first pressure medium passing through the pressure medium is an atmospheric atmosphere, and the second EE force medium passing through the pressure guiding pipe (17) is a pressurized atmosphere to be measured, then depending on the differential pressure between the first and second pressure medium, The diaphragm (21) of the pellet (20) curves downward, and the amount of change is converted into an amount of electricity by the piezoresistive portion (23), which is transferred to the outside via the lead pin (13). At this time, when the differential pressure becomes larger than a predetermined value, the thin film (16) is torn and the inside and outside of the container (10) communicate with each other, thereby eliminating the differential pressure and causing the diaphragm (21) to break. is prevented. Therefore, the sensor can be used again by closing the second through hole (15) with a new thin film. Since the thin film is located on the high pressure side, the broken thin film fragments are conveniently scattered outward and do not enter the cap (12). In addition, thin film (
Of course, the thickness of the diaphragm (16) is determined so that it ruptures before being destroyed by the excessive differential pressure of the diaphragm.For example, if the thickness of the diaphragm (21) is 20 μm, the thickness of the thin film (16) is approximately 10 μm. Appropriate.

In this way, the thin film (16) opens when the differential pressure of each pressure medium in contact with both sides of the diaphragm (21) reaches a predetermined level or more, thereby opening the thin film (16) to open the container (10) to communicate between the inside and outside of the container (10). However, a similar function can also be implemented in other forms, such as check valves that open outwards at a pressure difference above a certain level - in particular in the case of check valves, which automatically open again when said pressure difference falls. It closes automatically, so the sensor can continue to be used.

It is also possible to provide the differential pressure release means on the cap (12) side, or to configure the pressure medium with a liquid.

(f) Effects of the Invention According to the diaphragm type pressure sensor of the present invention, when an excessive pressure difference occurs with respect to the diaphragm, the pressure difference release means immediately removes the pressure difference, thereby avoiding destruction of the diaphragm.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing an embodiment of the present invention, in which (10) 4 is a container 11, (20) is a sensor pellet, and (16) is a thin film as a differential pressure release means.

Claims (1)

[Claims] (1) A diaphragm-type pressure sensor pellet is housed in a container, and when the pressure difference between the pressure media in contact with both sides of the diaphragm of the pellet exceeds a predetermined value, the pellet is opened by the pressure difference. A diaphragm type pressure sensor characterized in that the container is provided with differential pressure release means for communicating the inside and outside of the container. (2. In claim 1, the diaphragm pressure sensor is characterized in that the differential pressure release means is a fixed membrane. (3) In claim 1, the differential pressure release means is A diaphragm pressure sensor characterized in that it is a check valve. (4) In any one of claims 1 to 3, the differential pressure release means is configured to release pressure to the pressure medium on the high to pressure side. A diaphragm type pressure sensor characterized by being provided with a contact hole.