JP2008101989A - Sensor, its mounting structure and mounting method - Google Patents

Abstract

Deposits deposited and deposited in a gap between a detection portion of a pressure sensor and a sensor mounting hole adversely affect heat dissipation characteristics of the pressure sensor.
A sensor mounting structure according to the present invention in which an in-cylinder pressure sensor 10 is mounted in a sensor mounting hole 13 formed in a cylinder head 11 includes a small-diameter portion 10b having a detection portion 10a at a distal end and a large end portion positioned on a proximal end side. The in-cylinder pressure sensor 10 includes a diameter portion 10c and a step portion 10d positioned between the small diameter portion 10b and the large diameter portion 10c, and a small diameter hole portion 13a surrounding the small diameter portion 10b in a non-contact state. The sensor mounting hole 13 has a large-diameter hole portion 13b surrounding the large-diameter portion 10c, and a step hole portion 13c that is located between the small-diameter hole portion 13a and the large-diameter hole portion 13b and contacts the step portion 10d. In addition, the sealing agent 14 is filled between the small diameter portion 10 b and the small diameter hole portion 13 a, and an excess reservoir portion of the sealing agent 14 is formed between the in-cylinder pressure sensor 10 and the sensor mounting hole 13.
[Selection] Figure 2

Description

  The present invention relates to a sensor such as a pressure sensor incorporated in an internal combustion engine, a mounting structure thereof, and a mounting method.

  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. Sealing 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 is formed between the detection part on the tip side of the pressure sensor and the sensor mounting hole to reduce heat conduction between the detection part of the pressure sensor and the cylinder head so that the heat dissipation characteristics of the detection part do not change. Consideration.

Japanese Utility Model Publication No. 6-86049

  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 caused between the tip of the pressure sensor and the sensor mounting hole. It has been found that it adheres and accumulates in the annular gap between them and carbonizes and solidifies 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.

[Object of invention]
An object of the present invention is to provide a sensor capable of avoiding adverse effects due to the invasion of foreign matter, a mounting structure thereof, and a mounting method.

  The first embodiment of the present invention is a sensor mounting in which a sensor mounting hole having a small diameter hole, a large diameter hole, and a step hole located between the small diameter hole and the large diameter hole is formed. A small-diameter portion that is attached to the member and is filled with a sealant between the small-diameter hole portion of the sensor attachment hole, a large-diameter portion that is at least partially surrounded by the large-diameter hole portion of the sensor attachment hole, and these small diameters A sensor that is located between the small diameter portion and the large diameter portion, and has a step portion that contacts the step hole portion of the sensor mounting hole, and is located between the small diameter portion and the step portion; and Further, the sensor mounting hole is further provided with an escape portion that defines a reservoir of excess sealing agent.

  In the present invention, in the state where the sensor is mounted in the sensor mounting hole, the gap between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole is filled with the sealant, and the heat dissipation characteristics of the small diameter portion are defined by the sealant. . The relief portion formed in the sensor defines a part of a reservoir portion that accommodates excess sealing agent when the sensor is attached to the sensor mounting hole.

  In the sensor according to the first aspect of the present invention, the outer peripheral edge of the escape portion may abut on the stepped hole portion of the sensor mounting hole. Alternatively, the escape portion may have an annular groove portion having a smaller diameter than the small diameter portion.

  According to a second aspect of the present invention, there is provided a sensor mounting structure in which a sensor is mounted in a sensor mounting hole formed in a sensor mounting member, wherein the sensor is positioned at a proximal end side with a small diameter portion having a detection portion at a distal end. And a step portion positioned between the small diameter portion and the large diameter portion, and the sensor mounting hole includes a small diameter hole portion that surrounds the small diameter portion of the sensor in a non-contact state. A large-diameter hole that surrounds the large-diameter portion of the sensor, and a step-hole portion that is located between the small-diameter hole portion and the large-diameter hole portion and that contacts the step portion of the sensor, A sealant is filled between the small-diameter portion of the sensor and the small-diameter hole portion of the sensor mounting hole, and a surplus sealant reservoir is formed between the sensor, the stepped hole portion, and the small-diameter hole portion. It is characterized by this.

  In the present invention, the gap between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole is filled in advance with the sealant, and the heat dissipation characteristics of the small diameter portion are defined by the sealant. The reservoir portion functions as a portion that accommodates excess sealing agent when the sensor is attached to the sensor mounting hole.

  In the sensor mounting structure according to the second aspect of the present invention, the sensor mounting hole further includes an annular groove portion positioned between the small diameter hole portion and the step hole portion and having a larger diameter than the small diameter hole portion. The groove part may face the pool part.

  The sensor mounting member may be a cylinder head of an internal combustion engine, and the sensor may be a pressure sensor such as an in-cylinder pressure sensor using a piezoelectric element or the like or a combustion pressure sensor.

  According to a third aspect of the present invention, there is provided a method for mounting a sensor in a sensor mounting hole formed in a sensor mounting member, wherein the sensor is positioned on a proximal end side with a small diameter portion having a detection portion at a distal end. And a step portion positioned between the small diameter portion and the large diameter portion, and the sensor mounting hole includes a small diameter hole portion that surrounds the small diameter portion of the sensor in a non-contact state. A large-diameter hole that surrounds the large-diameter portion of the sensor, and a step-hole portion that is located between the small-diameter hole portion and the large-diameter hole portion and that contacts the step portion of the sensor, Forming a sealant layer around the small diameter portion of the sensor so as to have an outer diameter equal to or larger than an inner diameter of the small diameter hole portion of the sensor mounting hole, and forming the small diameter portion of the sensor on which the sealant layer is formed Insert from the large-diameter hole side of the sensor mounting hole, and the sensor, the stepped hole and the front A step of introducing surplus sealing agent into a gap formed between the small-diameter hole and a step of fixing the sensor step so that the stepped portion of the sensor is pressed against the stepped hole of the sensor mounting hole; It is characterized by comprising.

  In the present invention, when the small-diameter portion of the sensor in which the sealant layer is formed is inserted from the large-diameter hole side of the sensor mounting hole, an excess sealant is formed between the sensor and the step hole portion and the small-diameter hole portion. It is accommodated in the gap portion, and the sealant is filled without a gap between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole.

  In the sensor mounting method according to the third aspect of the present invention, prior to the step of forming the sealant layer around the small diameter part of the sensor, the step of masking the tip of the small diameter part of the sensor and the layer of the sealant are formed. Further, prior to the step of inserting the small diameter portion of the sensor from the large diameter hole portion side of the sensor mounting hole, a step of removing masking at the tip of the small diameter portion of the sensor can be further provided.

  According to the sensor of the present invention, the sensor is provided with a relief portion that is located between the small diameter portion and the step portion and that defines an accumulation portion of an excess sealant between the sensor mounting hole and the small diameter portion of the sensor. As a result of filling the gap between the sensor mounting hole and the small-diameter hole portion of the sensor mounting hole with the sealing agent, the heat dissipation characteristics of the small-diameter portion can be kept constant by the sealing agent. In addition, it is possible to prevent a problem that foreign matter or the like enters between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole.

  When the escape portion has an annular groove portion having a diameter smaller than that of the small diameter portion, the design of the volume of the reservoir portion can be relatively easily changed.

  According to the sensor mounting structure of the present invention, the sensor includes a small-diameter portion having a detection portion at the distal end, a large-diameter portion located on the proximal end side, and a step portion located between the small-diameter portion and the large-diameter portion. A small-diameter hole that surrounds the small-diameter portion of the sensor in a non-contact state, a large-diameter hole that surrounds the large-diameter portion of the sensor, and the sensor is positioned between the small-diameter hole and the large-diameter hole. The sensor mounting hole has a step hole portion with which the step portion contacts, and a sealant is filled between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole, and the sensor, the step hole portion and the small diameter hole portion Since the excess sealant reservoir is formed between the two, the heat dissipation characteristics of the small diameter part can be kept constant by the sealant. In addition, it is possible to prevent a problem that foreign matter or the like enters between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole.

  If the reservoir includes an annular groove that is located between the small-diameter hole and the large-diameter hole of the sensor mounting hole and has a larger diameter than the small-diameter hole, the volume of the reservoir should be designed relatively easily. Can do.

  According to the sensor mounting method of the present invention, the sealant layer is formed around the small diameter portion of the sensor so as to have an outer diameter equal to or larger than the inner diameter of the small diameter hole portion of the sensor mounting hole, and the sensor is provided with the sealant layer The small diameter part of the sensor is inserted from the large diameter hole side of the sensor mounting hole, and excess sealant is introduced into the gap formed between the sensor and the step hole part and the small diameter hole part, On the other hand, since the step portion of the sensor is fixed so as to be pressed in close contact, the sealing agent can be filled between the small diameter portion of the sensor and the sensor mounting hole without any gap. Moreover, since the surplus sealing agent is also accommodated in the gap, it is possible to prevent a problem that the sealing agent adheres to the detection portion of the sensor.

  Before forming the sealant layer around the small diameter part of the sensor, mask the tip of the small diameter part of the sensor and remove the small diameter part of the sensor with the sealant layer from the large diameter hole side of the sensor mounting hole. When the masking at the tip of the small diameter portion of the sensor is removed before insertion, it is possible to more reliably prevent a problem that the sealant adheres to the detection portion of the sensor.

  An embodiment in which the sensor according to the present invention is applied to an in-cylinder pressure sensor incorporated in a spark ignition engine will be described in detail with reference to FIGS. 1 to 5, but the present invention is not limited to such an embodiment. It can be applied to any other technique belonging to the spirit of the invention.

  FIG. 1 schematically shows a cross-sectional structure of the present embodiment before attachment of the in-cylinder pressure sensor, and FIG. 2 schematically shows a cross-sectional structure of the attachment state.

  The in-cylinder pressure sensor 10 in the present embodiment uses a piezoelectric element (electrostrictive element) to extract an electrical output corresponding to the amount of strain of the detection unit 10a, and uses fastening means (not shown) such as a screw. It is fixed to the cylinder head 11. The in-cylinder pressure sensor 10 is located between a small diameter portion 10b having a detection portion 10a facing the combustion chamber 12 at a distal end, a large diameter portion 10c located on the proximal end side, and the small diameter portion 10b and the large diameter portion 10c. And a stepped portion 10d. The step portion 10d in the present embodiment is formed by a conical surface having a tapered annular shape. The internal structure of the in-cylinder pressure sensor 10 itself is well known in the art and is not directly related to the present invention, so that the description thereof is omitted.

  A sensor mounting hole 13 formed in the cylinder head 11 has a small-diameter hole portion 13 a that communicates with the small-diameter portion 10 b of the in-cylinder pressure sensor 10 in a non-contact state with the in-cylinder pressure sensor 10. A large-diameter hole portion 13b that accommodates the large-diameter portion 10c, a step-hole portion 13c that is located between the small-diameter hole portion 13a and the large-diameter hole portion 13b and that contacts the step portion 10d of the in-cylinder pressure sensor 10, It has an annular groove part 13d that is located between the step hole part 13c and the small diameter hole part 13a and has a larger diameter than the small diameter hole part 13a. The step hole portion 13 c in the present embodiment is formed by a conical surface having a tapered annular shape corresponding to the step portion 10 d of the in-cylinder pressure sensor 10. In the present invention, the depth, that is, the inner diameter of the annular groove portion 13d that defines the reservoir portion is such that the contact width between the stepped portion 10d and the stepped hole portion 13c serving as a seal surface between the in-cylinder pressure sensor 10 and the sensor mounting hole 13 is too narrow. It is desirable from the standpoint of ensuring these sealing properties that they should not be set. Further, the groove width of the annular groove portion 13d, that is, the length along the direction parallel to the axis of the small diameter hole portion 13a (the vertical direction in the figure) is determined by the excess sealing agent 14 when the mounting method described later is carried out. It is necessary to set the length so as not to completely fill the annular groove 13d.

  In the present embodiment, the detection unit 10a of the in-cylinder pressure sensor 10 is positioned on the same plane with respect to the inner wall surface of the cylinder head 11 facing the combustion chamber 12, but in order to reduce the influence of thermal radiation due to the flame, You may make it make the position of the detection part 10a retreat from the inner wall face of the cylinder head 11 (separate from the combustion chamber 12).

  In addition, when using the in-cylinder pressure sensor in which the external thread portion is formed as the fastening means described above on the base end side (step portion 10d side) of the small diameter portion 10b, the internal thread portion and the small diameter hole portion of the sensor mounting hole into which the external thread portion is screwed. It is effective to form an annular groove portion 13d with 13a. That is, in any case, it is preferable to form the annular groove portion 13 adjacent to the small diameter hole portion 13a.

  Between the small-diameter portion 10b of the sensor and the small-diameter hole portion 13a of the sensor mounting hole 13, the above-described sealing agent 14 is filled without a gap. The sealing agent 14 may be any material that does not have fluidity and has stable physical and chemical properties and heat resistance, and a material mainly composed of carbon, alumina, spinel, aron ceramics, or the like may be employed. it can.

  As described above, since the sealing agent 14 is filled between the small diameter portion 10b of the in-cylinder pressure sensor 10 and the small diameter hole portion 13a of the sensor mounting hole 13, the combustion of fuel in the combustion chamber 12 is prevented. A foreign matter such as deposit generated along with this does not enter the periphery of the detection unit 10a. As a result, the heat radiation characteristic of the detection unit 10a of the in-cylinder pressure sensor 10 is kept constant by the sealant 14 surrounding the detection unit 10a, and stable measurement can be performed.

  The procedure of the method of attaching the in-cylinder pressure sensor 10 having such a structure will be described below. First, the detection portion 10a on the front end surface of the in-cylinder pressure sensor 10 is closed with a masking tape (not shown), and a subsequent sealing agent application operation is performed. At this time, the sealing agent 14 is prevented from adhering to the detection unit 10a.

  Next, the sealing agent 14 is applied to the outer periphery of the small diameter portion 10b of the in-cylinder pressure sensor 10 to form a sealing agent layer. The thickness of the sealing agent layer is set to be larger than the width of the gap between the small diameter portion 10b and the small diameter hole portion 13a, that is, the outer diameter of the sealing agent layer is set to be larger than the inner diameter of the small diameter hole portion 13a. It is preferable to do. The sealing agent 14 is required to be softer than the aluminum alloy constituting the cylinder head 11 in the present embodiment, which is a member that defines the sensor mounting hole 13, and specifically, carbon, alumina, Spinel, Aron ceramics, etc. are fixed to the outer periphery of the small-diameter portion 10b using any appropriate method such as dipping, spray coating, spraying, and baking.

  After forming the layer of the sealing agent 14 on the outer peripheral surface of the small diameter portion 10b of the sensor in this way, the masking tape is removed from the front end surface of the in-cylinder pressure sensor 10, and care is taken so that the front end surface does not hit the sensor mounting hole 13. The small diameter portion 10 b of the in-cylinder pressure sensor 10 is inserted from the large diameter hole portion 13 b side of the sensor mounting hole 13. A state in the middle of this insertion operation is shown in FIG. Since the outer diameter of the layer of the sealing agent 14 is larger than the inner diameter of the small-diameter hole portion 13a, the excess sealing agent 14 is peeled off at the boundary portion between the small-diameter hole portion 13a and the annular groove portion 13d and is deposited in the annular groove portion 13d. Go. As a result, the gap between the small diameter portion 10b and the small diameter hole portion 13a can be completely filled with the sealant 14. Finally, as shown in FIG. 2, the sensor step portion 10 d presses against the step hole portion 13 c of the sensor mounting hole 13 in a close contact state, and in this state, the in-cylinder pressure sensor 10 is fixed to the cylinder head 11. The

  If the thickness of the layer of the sealing agent 14 formed on the outer peripheral surface of the small diameter portion 10b is made too thick, the surplus sealing agent 14 will spread over the entire annular groove 13d in the process of inserting the in-cylinder pressure sensor 10 into the sensor mounting hole 13. It must be noted that the filling may flow to the sealing surface between the stepped portion 10d and the stepped hole portion 13c, which may impair these sealing properties.

  Without forming the annular groove 13d as described above, a gap serving as a reservoir for excess sealing agent 14 may be formed between the in-cylinder pressure sensor 10, the step hole 13c, and the small diameter hole 13a. . Such a structure of another embodiment of the present invention is schematically shown in FIGS. 4 and 5, but the same reference numerals are given to elements having the same functions as those of the previous embodiment, and duplicate descriptions are omitted. It shall be. That is, in the embodiment shown in FIG. 4, the shape of the in-cylinder pressure sensor 10 itself with respect to the sensor mounting hole 13 is utilized to remove excess sealing agent 14 between the in-cylinder pressure sensor 10 and the step hole 13c and the small diameter hole 13a. A gap 15 is formed as a reservoir. More specifically, an escape portion 10e that faces the gap portion 15 is formed between the step portion 10d of the step portion 10d of the in-cylinder pressure sensor 10 and the small diameter portion 10b, and thereby, a surplus seal agent 14 is accumulated. A gap 15 is defined. Since the outer peripheral edge of the relief portion 10e in this embodiment is in contact with the step hole portion 13c of the sensor mounting hole 13, the small diameter side of the step hole portion 13c also defines a part of the gap portion 15. It will be. In the embodiment shown in FIG. 5, an annular groove portion 10f having a diameter smaller than that of the small diameter portion 10b is formed between the small diameter portion 10b and the step portion 10d of the in-cylinder pressure sensor 10, and a portion surrounded by the annular groove portion 10f is a gap. Used as part 15. The present invention includes those having such a structure.

  In the above-described embodiment, the in-cylinder pressure sensor 10 has been described. However, other sensors such as a combustion pressure sensor for detecting the pressure of the fuel supplied to the combustion chamber 12 of the internal combustion engine and the mounting structure and mounting method thereof are also applicable. Needless to say, it can be applied.

  As described above, the present invention should be construed only from the matters described in the scope of the claims, and in the above-described embodiments, the matters described in all the changes and modifications included in the concept of the present invention are described. Other than possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

It is an exploded sectional view showing typically the state before attachment in one embodiment which applied the present invention to the cylinder pressure sensor. It is sectional drawing which represents typically the state after mounting | wearing of the cylinder pressure sensor shown in FIG. It is sectional drawing which represents typically the state in the middle of attachment of the in-cylinder pressure sensor shown in FIG. It is sectional drawing which represents typically other embodiment which applied this invention to the cylinder pressure sensor. It is sectional drawing which represents typically another embodiment which applied this invention to the cylinder pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 In-cylinder pressure sensor 10a Detection part 10b Small diameter part 10c Large diameter part 10d Step part 10e Relief part 10f Annular groove part 11 Cylinder head 12 Combustion chamber 13 Sensor mounting hole 13a Small diameter hole part 13b Large diameter hole part 13c Step hole part 13d Annular groove part 14 Sealant 15 Cavity

Claims (6)

A sensor mounting member having a small-diameter hole portion, a large-diameter hole portion, and a step-hole portion positioned between the small-diameter hole portion and the large-diameter hole portion is attached to the sensor attachment member, A small-diameter portion filled with a sealant between the small-diameter hole portion, a large-diameter portion at least partially surrounded by the large-diameter hole portion of the sensor mounting hole, and between the small-diameter portion and the large-diameter portion. A sensor that is positioned and has a stepped portion that abuts against the stepped hole portion of the sensor mounting hole,
A sensor further comprising an escape portion located between the small diameter portion and the step portion and defining a reservoir portion of an excess sealing agent between the sensor mounting hole.   The sensor according to claim 1, wherein the escape portion has an annular groove portion having a smaller diameter than the small diameter portion. A sensor mounting structure in which a sensor is mounted in a sensor mounting hole formed in a sensor mounting member,
The sensor includes a small-diameter portion having a detection portion at a distal end, a large-diameter portion located on the base end side, and a step 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 sensor in a non-contact state, a large diameter hole portion that surrounds the large diameter portion of the sensor, and the small diameter hole portion and the large diameter hole portion. And a step hole portion with which the step portion of the sensor abuts,
A sealant is filled between the small diameter portion of the sensor and the small diameter hole portion of the sensor mounting hole,
A sensor mounting structure, wherein a surplus sealant reservoir is formed between the sensor and the sensor mounting hole.   The sensor mounting hole is located between the small diameter hole portion and the step hole portion, and further has an annular groove portion having a diameter larger than that of the small diameter hole portion, and the annular groove portion faces the pool portion. The sensor mounting structure according to claim 3, wherein: A method for mounting a sensor in a sensor mounting hole formed in a sensor mounting member,
The 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 step 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 sensor in a non-contact state, a large diameter hole portion that surrounds the large diameter portion of the sensor, and the small diameter hole portion and the large diameter hole portion. And a step hole portion with which the step portion of the sensor abuts,
Forming a sealant layer around the small diameter portion of the sensor so as to have an outer diameter equal to or larger than the inner diameter of the small diameter hole portion of the sensor mounting hole;
Insert the small-diameter portion of the sensor in which the layer of the sealing agent is formed from the large-diameter hole side of the sensor mounting hole, and put an excess of the sealing agent in the gap formed between the sensor and the sensor mounting hole. A guiding step,
And a step of fixing the stepped portion of the sensor so that the stepped portion of the sensor is pressed in close contact with the stepped hole portion of the sensor mounting hole. Masking the tip of the small diameter portion of the sensor prior to forming the layer of the sealing agent around the small diameter portion of the sensor; and
Prior to the step of inserting the small diameter portion of the sensor formed with the sealant layer from the large diameter hole portion side of the sensor mounting hole, and further removing the masking of the tip of the small diameter portion of the sensor. The sensor mounting method according to claim 5, wherein:

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