JP2008268129A - Pressure sensor mounting structure - Google Patents

Abstract

A pressure sensor mounting structure capable of avoiding adverse effects caused by deposit intrusion is provided.
A pressure sensor includes a small-diameter portion having a detection portion at a distal end, a large-diameter portion located on a proximal end side, and a seal portion located between the small-diameter portion and the large-diameter portion. The sensor mounting hole 201 includes a small diameter hole 202 surrounding the small diameter part 101 of the pressure sensor 100 in a non-contact state, a large diameter hole 203 surrounding the large diameter part 102 of the pressure sensor 100, and A step hole portion 204 is provided between the small diameter hole portion 202 and the large diameter hole portion 203 and the seal portion 33 of the pressure sensor contacts with the small diameter portion 101 of the pressure sensor 100 and the sensor mounting hole 201. A bellows seal 300 is mounted in the gap between the small diameter hole portion 202.
[Selection] Figure 1

Description

  The present invention relates to a pressure sensor mounting structure incorporated in an internal combustion engine.

  A pressure sensor that detects various pressures in a combustion chamber of an internal combustion engine using a piezoelectric element or the like is known from Patent Document 1. This pressure sensor is attached to a sensor mounting hole formed in a cylinder head or the like. The seal between the pressure sensor and the sensor mounting hole is performed by pressing an annular shoulder formed in the pressure sensor against an annular step formed in the sensor mounting hole. A gap (processing clearance) is formed between the detection portion and the sensor mounting hole.

Japanese Utility Model Publication No. 6-86049

  By the way, when the in-cylinder pressure of an internal combustion engine is detected using a pressure sensor as disclosed in Patent Document 1, an organic compound generated with the combustion of fuel in the combustion chamber is removed from the tip of the pressure sensor and the sensor mounting hole. Intrusions and deposits in the voids (processing clearance) between them and tends to carbonize and solidify over time. Such deposits, so-called deposits, become a heat transfer medium between the detection part of the pressure sensor and the cylinder head. Since the temperature change of the detection unit is a large factor that affects the measurement accuracy of the pressure sensor, the change in the heat dissipation characteristics of the detection unit due to the deposit causes a decrease in the reliability of the detection value by the pressure sensor. Further, if deposits are accumulated in the gap (processing clearance), the pressure sensor may be destroyed when the pressure sensor is removed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure sensor mounting structure capable of avoiding adverse effects caused by deposit intrusion.

  A pressure sensor mounting structure according to the present invention is a pressure sensor mounting structure in which a pressure sensor is mounted in a sensor mounting hole formed in a sensor mounting member, and the pressure sensor includes a small-diameter portion having a detection portion at a tip thereof. A large-diameter portion located on the proximal end side and a seal portion located between the small-diameter portion and the large-diameter portion, and the sensor mounting hole is in a non-contact state with respect to the small-diameter portion of the pressure sensor. A small-diameter hole that surrounds the large-diameter hole that surrounds the large-diameter portion of the pressure sensor, and a step that is located between the small-diameter hole and the large-diameter hole and that the seal portion of the pressure sensor contacts. And a bellows seal is mounted in a gap between the small diameter portion of the pressure sensor and the small diameter hole portion of the sensor mounting hole.

  According to this configuration, since the bellows seal is mounted in the gap between the small diameter portion of the pressure sensor and the small diameter hole portion of the sensor mounting hole, the gap between the small diameter portion of the pressure sensor and the small diameter hole portion of the sensor mounting hole is Deposits can be prevented from accumulating in the voids.

  In the above configuration, the bellows seal is made of metal and is elastically deformable, and is in contact with the outer peripheral surface of the small diameter portion of the sensor and the inner peripheral surface of the small diameter hole portion of the sensor mounting hole. Configuration can be adopted.

  According to this configuration, the metal bellows seal is in contact with the outer peripheral surface of the small diameter portion of the sensor and the inner peripheral surface of the small diameter hole portion of the sensor mounting hole, thereby increasing the heat dissipation of the pressure sensor and stabilizing the detection characteristics. Turn into.

  According to the present invention, it is possible to reliably prevent the deposit from entering between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole by the bellows seal, and it is possible to avoid an adverse effect due to the penetration of the deposit.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic cross-sectional view showing a mounting structure for a sensor mounting hole formed in a cylinder head 200 as a sensor mounting member of a pressure sensor 100 according to an embodiment of the present invention.

  The pressure sensor 100 includes a small-diameter portion 101 having a pressure-receiving diaphragm 10 as a detection portion at a distal end, a large-diameter portion 102 located on the proximal end side, a connector portion 103 connected to the large-diameter portion 102, a small-diameter portion 101 and a large-diameter portion. The seal portion 33 is located between the diameter portion 102 and the like.

  On the other hand, the sensor mounting hole 201 formed in the cylinder head 200 communicates with the combustion chamber 205, and the sensor mounting hole 201 surrounds the small diameter portion 101 of the pressure sensor 100 in a non-contact state. 202, a large-diameter hole portion 203 surrounding the large-diameter portion 102 of the pressure sensor 100, and a stage located between the small-diameter hole portion 202 and the large-diameter hole portion 203 and the seal portion 33 of the pressure sensor 100 abuts. And a hole 204.

  In the pressure sensor 100, the pressure receiving diaphragm 10, the cylindrical metal case 20, the cylindrical metal stem 30, and the cylindrical housing 40 are integrated by welding, brazing, adhesion, or the like. The connector portion 103 is connected to the housing 40.

  The housing 40 is made of, for example, a metal such as stainless steel, and a screw portion 41 for fixing to the large-diameter hole portion 203 of the sensor mounting hole 201 is formed on the outer surface thereof. That is, the pressure sensor 100 is fixed to the large-diameter hole 203 formed by the screw hole of the cylinder head 200 by screw connection.

  The metal stem 30 is a member made of metal such as stainless steel processed into a hollow cylindrical shape. The end on the metal case 20 side is an opening 31, and the end on the housing 40 side is a thin distortion portion 32. Yes.

  The strained portion 32 of the metal stem 30 is distorted by the application of the pressure P received by the pressure receiving diaphragm 10. The strainer 32 is provided with a detection element 50 that generates a signal based on the strain due to the pressure P.

  The above-described seal portion 33 is formed on the outer peripheral surface of the metal stem 30, and this seal portion 33 is a tapered surface as shown in FIG. 1, and the pressure sensor 100 is screwed into the sensor mounting hole 201. At this time, the sensor mounting hole 201 is sealed by closely contacting (contacting) the stepped hole portion 204.

  The metal case 20 is made of metal such as stainless steel, and is fitted into and fixed to the opening 31 of the metal stem 30. The pressure receiving diaphragm 10 is joined to the tip of the metal case 20.

  The pressure receiving diaphragm 10 is, for example, a metal circular plate such as stainless steel, and is deformed and deformed by application of pressure P.

  A pressure transmission member 60 is provided in the space formed by the hollow portion of the metal stem 30 and the hollow portion of the metal case 20. The pressure transmission member 60 is formed in a rod shape with a metal such as stainless steel or a material such as ceramics.

  Each end of the pressure transmission member 60 is in contact with the strained portion 32 of the metal stem 30 and the pressure receiving diaphragm 10 in a state where a load is applied, and the pressure P is applied to the pressure transmission member 60 from the pressure receiving diaphragm 10. It is applied to the strained portion 32 of the metal stem 30 through.

  The pressure P received by the pressure receiving diaphragm is transmitted to the distortion portion 32 of the metal stem 30, and a signal is output from the detection element 50 based on the distortion of the distortion portion 32.

  A wiring substrate 42 made of a ceramic substrate or the like is provided inside the housing 40. An IC chip 43 is mounted on the wiring board 42 and is electrically connected to the wiring board 42. The IC chip 43 forms a circuit for amplifying and adjusting the output from the detection element 50.

  In the housing 40, the IC chip 43 and the detection element 50 are electrically connected by a wiring member 44. As the wiring member 44, a lead wire, a flexible printed circuit board, etc. are employ | adopted.

  The connector portion 103 described above is connected to the housing 40 via an O-ring 45. The connector portion 103 is made of a resin such as PPS (polyphenylene sulfide), and a metal terminal 103a is integrated with the connector portion 103 by insert molding or the like.

  The connector portion 103 is assembled to the housing 40 with one end side inserted into the opening portion of the housing 40, and the edge portion of the opening portion of the housing 40 is caulked to the connector portion 103, whereby the connector portion 103 and the housing 40 are assembled. And are integrally fixed.

  In the housing 40, the terminal 103 a of the connector portion 103 is electrically connected to the wiring board 42. The terminal 103a can be electrically connected to an electronic control unit (ECU) or the like of the automobile, whereby the pressure sensor 100 can exchange signals with the outside.

  A gap (processing clearance) CL is formed between the small diameter portion 101 of the pressure sensor 100 and the small diameter hole portion 202 of the sensor mounting hole 201. The width of the gap CL is, for example, about 0.5 mm. A bellows seal 300 is attached to the gap CL.

  As shown in FIG. 2, the bellows seal 300 is formed in a bellows shape, and is formed of a metal material having durability and corrosion resistance such as SUS630 (precipitation hardening treatment) or Inconel.

  The bellows seal 300 is formed to be elastically deformable, and as shown in FIG. 1, the outer peripheral surface and inner peripheral surface thereof are the outer peripheral surface of the small diameter portion 101 of the pressure sensor 100 and the small diameter hole of the sensor mounting hole 201. It arrange | positions so that it may contact with the internal peripheral surface of the part 202, respectively.

  Further, the bellows seal 300 is disposed over substantially the entire length of the small diameter portion 101 of the pressure sensor 100.

  The bellows seal 300 is fixed in the gap CL between the small diameter portion 101 of the pressure sensor 100 and the small diameter hole portion 202 of the sensor mounting hole 201 by elastic deformation, but there are various methods for fixing the bellows seal 300. Can be adopted.

  As described above, by arranging the bellows seal 300 in the gap CL between the small diameter portion 101 of the pressure sensor 100 and the small diameter hole portion 202 of the sensor mounting hole 201, the small diameter portion 101 of the pressure sensor 100 and the sensor mounting hole 201 are disposed. It is possible to reliably prevent the deposit generated in the combustion chamber from entering the gap CL formed between the small-diameter hole portion 202 and the deposit does not accumulate in the gap CL. As a result, it can suppress that the detection characteristic of the pressure sensor 100 changes.

  Further, since the metal bellows seal 300 is in contact with the substantially entire length of the small diameter portion 101 and the small diameter hole portion 202 of the pressure sensor 100, a large heat conduction area can be secured, and the pressure sensor 100 can be connected to the cylinder via the bellows seal 300. Heat is easily radiated to the head 200. Thereby, the influence of the heat to the pressure sensor 100 can be relieved.

It is a schematic sectional drawing which shows the attachment structure of the pressure sensor which concerns on one Embodiment of this invention. It is a figure which shows the external appearance of a bellows seal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Diaphragm 20 for receiving pressure ... Metal case 30 ... Metal stem 33 ... Seal part 40 ... Housing 50 ... Detection element 60 ... Pressure transmission member 100 ... Pressure sensor 101 ... Small diameter part 102 ... Large diameter part 103 ... Connector part 200 ... Cylinder head (Sensor mounting member)
201 ... Sensor mounting hole 202 ... Small diameter hole 203 ... Large diameter hole 204 ... Step hole 205 ... Combustion chamber 300 ... Bellows seal CL ... Air gap

Claims (2)

A pressure sensor mounting structure in which a pressure sensor is mounted in a sensor mounting hole formed in a sensor mounting member,
The pressure sensor includes a small diameter portion having a detection portion at a distal end, a large diameter portion located on the proximal end side, and a seal portion located between the small diameter portion and the large diameter portion,
The sensor mounting hole includes a small diameter hole portion that surrounds the small diameter portion of the pressure sensor in a non-contact state, a large diameter hole portion that surrounds the large diameter portion of the pressure sensor, and the small diameter hole portion and the large diameter hole. A step hole portion that is located between the pressure sensor and the seal portion of the pressure sensor contacts,
A pressure sensor mounting structure, wherein a bellows seal is mounted in a gap between the small diameter portion of the pressure sensor and the small diameter hole portion of the sensor mounting hole. The bellows seal is made of metal and elastically deformable,
The pressure sensor mounting structure according to claim 1, wherein the pressure sensor is in contact with an outer peripheral surface of the small-diameter portion of the pressure sensor and an inner peripheral surface of the small-diameter hole portion of the sensor mounting hole.

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