JP4301077B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor using a semiconductor for measuring the pressure of each part of an internal combustion engine, and more particularly to a structure for preventing a pressure introduction hole from being blocked by dust or the like.

Diesel engines have recently become stricter in exhaust gas regulations, especially NOx (nitrogen oxide) reduction, and therefore, it is necessary to lower the combustion temperature. For this reason, EGR (Exhaust Gas
The amount of recirculation is increased, and a large amount of particulate matter such as carbon comes out to the intake side. In general, a pressure sensor is used for EGR flow measurement.

  Further, the DPF (Diesel Particle Filter) method is currently most effective for reducing particulate matter such as carbon in the exhaust gas, and a pressure sensor is used for detecting filter clogging.

  Any pressure sensor is installed in an environment where it is exposed to a large amount of particulate matter such as carbon.

  In the conventional pressure sensor, a semiconductor pressure sensor 2 is attached to an intake manifold or an EGR return passage 1 as shown in FIG. At this time, the pressure introducing hole 3 of the normal pressure sensor has a large inner diameter but no protective wall is provided. Therefore, although there is a time difference, the dust 5 deposited on the wall surface 4 of the passage 1 does not cover the wall surface. There was a drawback that it was transmitted and deposited, and eventually closed the introduction hole. In particular, a cooler mechanism has recently been installed in the EGR path to lower the temperature of the exhaust gas to be recirculated, so that it becomes moist soot and easily adheres to the wall surface. It is easy to block. If the pressure introduction hole is blocked, the pressure cannot be accurately transmitted to the pressure sensor, and the pressure sensor cannot transmit the correct pressure signal to the engine control control unit, which has a problem that adversely affects engine control and the like. .

  Japanese Patent Application Laid-Open No. 2002-181651 discloses a structure for preventing contamination of a sensor chip of a pressure sensor. This structure is such that dirt does not adhere to the sensing part of the sensor chip, but no consideration is given to the problem that dust or the like adheres to the inlet part of the pressure introduction hole and blocks the introduction hole.

JP 2002-181651 A

An object of the present invention is to provide a pressure sensor that prevents the pressure introduction hole from being blocked by the accumulation of dust near the pressure introduction hole entrance .

The object is to provide a rubber sensor in which a hole is formed in a pressure sensor including a housing for forming a pressure introduction hole and a semiconductor for converting a pressure change of a medium to be measured introduced through the pressure introduction hole into an electric signal. An elastic body is provided, and the rubber-like elastic body is installed in the pressure introducing hole so that a tip portion protrudes from the housing, and the inflow of dust is suppressed in a portion which becomes an inner surface of the hole of the rubber-like elastic body A plurality of protective walls are formed, a slit is provided in the tip of the rubber-like elastic body and the protective wall, and pressure is introduced into the semiconductor through a hole in the rubber-like elastic body. This is achieved by a pressure sensor characterized in that.

According to the present invention, that Do is possible to prevent a problem blocking the pressure introduction hole with a material such as dust deposited on the vicinity of the pressure introducing hole of the pressure sensor. For example, even under highly polluted environmental conditions when used in a diesel engine or the like, the pressure introduction hole is not blocked by soot, and the engine control is not adversely affected and the reliability can be improved.

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

  FIG. 2 is a cross-sectional view when a semiconductor pressure sensor according to an embodiment of the present invention is mounted in a passage such as an intake manifold.

  In the pressure sensor, the pressure of the measurement medium is transmitted to the sensor chip 11 equipped with a semiconductor strain gauge through the pressure introduction hole 3 provided in the housing 10. The sensor chip is protected with a substance 12 on the gel for protection. The sensor chip is mounted on the case 13 and connected to a terminal 14 provided on the case by wire bonding 15 to supply power and output signals. The terminal 14 is connected to a connector terminal 16 insert-molded in the housing 10 by welding at a projection portion 17. The case 13 is fixed by casting an epoxy resin 18, and the epoxy resin 18 prevents pressure leakage. The connector portion 19 is connected to an external power supply / signal output harness together with the connector terminal 16.

In the present embodiment, the dust inflow protective wall 20 installed in the pressure introducing hole is separated from the rubber elastic body. First, by adopting a structure in which the protective wall 21 at the distal end protrudes into the passage, the inflow of dust that travels through the wall surface into the pressure introduction hole is prevented. At this time, the material of the protective wall 21 is made of a rubber-like elastic body (for example, silicone rubber, fluorine rubber, fluorosilicone rubber, etc.), so that the protective wall 21 vibrates when the flow velocity of the pressure medium in the passage changes. In addition, even if dust adheres to the protective wall 21, there is an effect of shaking off. At this time, it is more effective to provide the slit portion 22 so that the protective wall easily vibrates.

  Further, a protective wall 23 is provided on the inner surface of the pressure introducing hole to suppress the inflow of dust. The protective wall 23 is directed downward so that it is easy to fall even if dust adheres. This protective wall 23 vibrates with the pressure change caused by the change in the flow velocity of the pressure measuring medium when the main protective wall is made of a rubber-like elastic body, as in the case of the protective wall 21 part. Drop it. Further, by providing a slit portion in the same manner as the protective wall 21, the protective wall is easily vibrated, and the effect of dropping the attached dust is improved. Providing a plurality of protective walls 23 inside the pressure introduction hole 3 has an effect of further suppressing dust entering the inside.

  The dust inflow protective wall 20 is provided with a flange portion 24 for preventing excessive insertion and a flange portion 25 for preventing dropping, and is installed in the pressure sensor pressure introduction hole.

  FIG. 3 is a view showing only the dust inflow protection wall 20 installed in the pressure sensor pressure introduction hole of FIG. 2 which is an embodiment of the present invention.

  The upper part of FIG. 3 is a view of the dust inflow protection wall 20 as viewed from above. The middle part is a longitudinal sectional view, and the lower part is a view as seen from the top. The pressure introducing hole 3 has a shape divided by the slit portion of the protective wall 23 when viewed from above or below.

  An object of the present invention is to prevent pressure introduction holes due to dust of a semiconductor pressure sensor for an internal combustion engine from being blocked by dust, but pressure used in an environment where dust is contained in a pressure measurement medium. It can be applied to the pressure introduction hole structure of the sensor.

Sectional drawing of the pressure introduction hole part of the conventional pressure sensor. Sectional drawing of the pressure sensor which provided the dust protection wall of this invention. FIG. 3 is a cross-sectional view of only the dust protection wall in FIG. 2 and a view from above and below.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Passage | path, 2 ... Pressure sensor, 3 ... Pressure introduction hole, 4 ... Wall surface, 5 ... Dust, 23 ... Protective wall.

Claims (2)

A housing forming a pressure introducing hole;
In the pressure sensor having a semiconductor for converting a pressure change of the medium to be measured introduced via the pressure introduction hole into an electric signal,
It has a rubbery elastic body with holes,
The rubber-like elastic body is installed in the pressure introducing hole so that the tip portion protrudes from the housing,
A plurality of protective walls for suppressing the inflow of dust are formed on the inner surface of the hole of the rubber-like elastic body,
A slit is provided in the tip portion of the rubber-like elastic body and the protective wall,
A pressure sensor configured to introduce pressure into the semiconductor through a hole of the rubber-like elastic body . In claim 1,
A pressure sensor, wherein the rubber-like elastic body is made of silicone rubber, fluorine rubber, or fluorosilicone rubber .

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