JP2021009118A - Cylinder inner pressure sensor - Google Patents

Abstract

To provide a cylinder inner pressure sensor that is able to improve the strength of a cap portion.SOLUTION: A cylinder inner pressure sensor comprises: a cap portion comprising a cylindrical first part having on an outer peripheral surface thereof a tapering surface abutting on an engine, and a cylindrical second part having on an outer peripheral surface thereof a cylindrical surface continuing to an axial rear-end side of the first part; a membrane joined to the first part via a first weld part; and a diaphragm joined to the second part via a second weld part and that deforms as the membrane deforms. An inner peripheral surface of the cap portion has a plurality of steps that are located nearer to the axis as they extend to the leading-end side. In a cross-section including the axis, the position of the intersection of the tapering surface and the cylindrical surface is located on the leading-end side from the position of the root of the following leading-end side step from the step nearest to the second weld part.SELECTED DRAWING: Figure 2

Description

The present invention relates to an in-cylinder pressure sensor that detects the pressure in the combustion chamber of an engine.

As an in-cylinder pressure sensor, Patent Document 1 inputs a cylindrical cap portion, a membrane arranged at the opening of the cap portion and deforms according to the in-cylinder pressure, and a force corresponding to the deformation of the membrane by a displacement member. Those provided with a diaphragm and a sensor element that outputs a signal corresponding to the distortion of the diaphragm are disclosed. A conical tapered surface that abuts on the engine and a cylindrical surface that is continuous with the rear end side of the tapered surface are formed on the outer peripheral surface of the cap portion. The in-cylinder pressure sensor is attached with the tapered surface of the cap portion pressed against the engine.

JP-A-2017-40516

In the technique of Patent Document 1, there is a demand for improving the strength of the cap portion so that there is no risk of damage even if an excessive force due to vibration or the like is applied to the cap portion from the engine.

The present invention has been made in order to meet this demand, and an object of the present invention is to provide an in-cylinder pressure sensor capable of improving the strength of the cap portion.

In order to achieve this object, the in-cylinder pressure sensor of the present invention has a cylindrical first portion and a first portion in which the diameter is increased toward the rear end in the axial direction and a tapered surface in contact with the engine is formed on the outer peripheral surface. A cap portion having a cylindrical second portion formed on the outer peripheral surface having a cylindrical surface connected to the rear end side in the axial direction of the above and connected to the tapered surface is joined to the first portion via a first welded portion. A membrane that closes the opening of the first part and deforms in response to pressure, and a displacement member that is located at the rear end of the membrane and has a rod shape extending along the axis and is displaced in the axial direction as the membrane is deformed. It is provided with a diaphragm that is joined to the two parts via a second weld and deforms with the displacement of the displacement member, and a sensor element that is arranged on the diaphragm and outputs a signal based on the strain amount of the diaphragm. A plurality of steps located closer to the axis toward the tip side are formed on the inner peripheral surface, and the position of the intersection of the tapered surface and the cylindrical surface is the step closest to the second weld in the cross section including the axis. It is on the tip side of the position of the base of the step on the next tip side.

According to the in-cylinder pressure sensor according to claim 1, the position of the intersection of the tapered surface and the cylindrical surface of the cap portion in the cross section including the axis is the step from the step closest to the second weld to the next tip side. It is on the tip side of the position of the base. As a result, the radial distance between the base of the step and the outer peripheral surface of the cap portion can be increased as compared with the case where the position of the intersection is on the rear end side of the position of the base of the step. , The area of the cut surface perpendicular to the axis at the base of the step can be increased. Stress concentration is likely to occur at the base of the step and it is likely to be the starting point of fracture. However, since the stress is reduced by increasing the cross-sectional area of the base of the step, the strength of the cap portion can be improved.

According to the in-cylinder pressure sensor according to claim 2, the length of the line segment that passes through the base of the step and intersects the tapered surface perpendicularly in the cross section including the axis is shorter than the length of the tapered surface. As a result, the heat transferred from the membrane to the first portion of the cap portion can be easily transferred from the tapered surface of the first portion to the engine, and can be difficult to transfer to the second portion of the cap portion. As a result, it is possible to make it difficult to transfer heat to the diaphragm bonded to the second portion, so that in addition to the effect of claim 1, the thermal influence of the sensor element arranged on the diaphragm can be suppressed.

It is a partial cross-sectional view of the in-cylinder pressure sensor in the 1st Embodiment. It is sectional drawing of the in-cylinder pressure sensor. It is an enlarged view of the part shown by III of FIG. It is sectional drawing of the cap part. It is sectional drawing of the cap part. It is sectional drawing of the in-cylinder pressure sensor in 2nd Embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional view of the in-cylinder pressure sensor 10 according to the first embodiment. FIG. 2 is a cross-sectional view including the axis O of the in-cylinder pressure sensor 10, and FIG. 3 is an enlarged view of a portion shown by III in FIG. In FIG. 2, the rear end side of the in-cylinder pressure sensor 10 is not shown. The lower side of the paper surface in FIG. 1 is referred to as the front end side of the in-cylinder pressure sensor 10, and the upper side of the paper surface is referred to as the rear end side of the in-cylinder pressure sensor 10 (the same applies to FIGS. 2 to 6).

As shown in FIG. 1, the in-cylinder pressure sensor 10 is a device that detects the pressure in the combustion chamber 103 in a state of being attached to the engine 100. The in-cylinder pressure sensor 10 includes a housing 11 extending along the axis O. In FIG. 1, the cable arranged in the housing 11 is not shown (the same applies in FIG. 2).

The housing 11 is made of a metal material having heat resistance and gas resistance (for example, stainless steel, low carbon steel, etc.). The housing 11 includes a shaft portion 12 formed in a cylindrical shape and a cap portion 13 connected to the tip of the shaft portion 12. A screw portion 14 and a tool engaging portion 15 are provided on the outer peripheral surface of the housing 11.

The screw portion 14 is a male screw that is formed in the screw hole 101 of the engine 100 and is therefore attached to a screw (not shown). The tool engaging portion 15 is a portion where a tool (not shown) such as a wrench used for tightening the screw portion 14 is engaged. The screw hole 101 of the engine 100 is connected to the combustion chamber 103. In the engine 100, an annular contact surface 102 facing the opposite side of the combustion chamber 103 is formed on the inner surface of the screw hole 101 that is closer to the combustion chamber 103 than the female screw.

As shown in FIG. 2, in the housing 11, the shaft portion 12 and the cap portion 13 are arranged in this order from the rear end side to the front end side. The shaft portion 12 is a member whose tip portion is formed in a cylindrical shape at least. The cap portion 13 is a cylindrical member in which a conical tapered surface 16 whose diameter increases toward the rear end and a cylindrical surface 17 connected to the rear end side of the tapered surface 16 are formed on the outer peripheral surface. When the screw portion 14 of the housing 11 is tightened into the screw hole 101 of the engine 100, the tapered surface 16 is pressed against the contact surface 102 of the engine 100 by an axial force.

The cap portion 13 includes a first portion 19 on the front end side of the intersection 18 of the tapered surface 16 and the cylindrical surface 17, and a second portion 22 on the rear end side of the intersection 18. The cap portion 13 including the first portion 19 and the second portion 22 is integrally made by cutting, forging, or the like. The boundary between the first part 19 and the second part 22 is a plane perpendicular to the axis O.

As shown in FIG. 3, the cap portion 13 has an annular tip surface 20 connected to the tip end side of the tapered surface 16 and an annular tip surface located inside the tip surface 20 in the radial direction and on the rear end side of the tip surface 20. It has a facing surface 21 and. The tip-facing surface 21 is a surface on which the membrane 30 is arranged.

It will be described back to FIG. The membrane 30 is a thin metal circular thin membrane that closes the opening of the first portion 19. The heat receiving plate 31 is a thin metal circular plate that covers the membrane 30. The entire circumference of the edge portion of the membrane 30 is joined to the tip facing surface 21 of the cap portion 13 by the first welded portion 32. In the present embodiment, the first welded portion 32 is a welded portion formed by a laser beam irradiated to the membrane 30.

The heat receiving plate 31 is joined to the inner portion of the membrane 30 in the radial direction from the first welded portion 32 by the third welded portion 33. In the present embodiment, the third welded portion 33 is a point-shaped welded portion formed by a laser beam irradiated to the center of the heat receiving plate 31. Since the third welded portion 33 is formed in the center of the heat receiving plate 31, the third welded portion 33 can hardly exert the influence of the radial thermal expansion and contraction of the heat receiving plate 31 on the membrane 30.

The membrane 30 is provided with a columnar displacement member 34 extending from the center of the membrane 30 toward the rear end side along the axis O. In the present embodiment, the membrane 30 and the displacement member 34 are integrally formed by, for example, forging or cutting, using a metal material such as stainless steel. However, the present invention is not limited to this, and it is naturally possible to integrate the membrane 30 and the displacement member 34 by welding or the like after forming the membrane 30 and the displacement member 34 separately.

A connecting member 35 and a diaphragm 40 are arranged between the displacement member 34 and the housing 11. The connecting member 35 is a metal cylindrical member arranged along the displacement member 34 on the outer side in the radial direction of the displacement member 34. The connecting member 35 is provided with an annular first overhanging portion 36 that projects outward in the radial direction from the tip end portion of the connecting member 35. The fourth weld 37 joins the rear end of the connecting member 35 to the rear end of the displacement member 34. In the present embodiment, the fourth welded portion 37 is a welded portion formed by irradiation with a laser beam.

The diaphragm 40 is a metal annular member arranged between the connecting member 35 and the housing 11. The diaphragm 40 includes an annular film portion 41 arranged perpendicular to the axis O, and a cylindrical first tubular portion extending from a portion of the film portion 41 on the displacement member 34 side to the tip side along the displacement member 34. A second tubular portion 43 having a shape extending from a portion of the film portion 41 on the housing 11 side to the tip end side along the inner peripheral surface of the housing 11 is provided. The axial length of the second tubular portion 43 is shorter than the axial length of the first tubular portion 42. The second tubular portion 43 is provided with an annular second overhanging portion 44 that projects outward in the radial direction from the vicinity of the center in the axial direction of the second tubular portion 43.

The first tubular portion 42 is arranged on the rear end side of the connecting member 35 with respect to the first overhanging portion 36. The tip of the first tubular portion 42 is abutted against the first overhanging portion 36. The second overhanging portion 44 of the diaphragm 40 is arranged between the shaft portion 12 and the cap portion 13. The film portion 41, the first tubular portion 42, the second tubular portion 43, and the second overhanging portion 44 are integrally molded.

The fifth weld 45 joins the tip of the connecting member 35 to the tip of the first cylinder 42. The second welded portion 46 joins the rear end portion 23 (see FIG. 3) of the second portion 22 to the second overhanging portion 44 over the entire circumference. The sixth welded portion 47 joins the tip end portion of the shaft portion 12 to the second overhanging portion 44 over the entire circumference. In the present embodiment, the fifth welded portion 45, the second welded portion 46, and the sixth welded portion 47 are welded portions formed by irradiation with a laser beam.

A sensor element 48 is fixed to the diaphragm 40. The sensor element 48 is a strain gauge that converts the mechanical strain amount of the diaphragm 40 into an electric amount. Two sensor elements 48 are fixed at two locations sandwiching the axis O of the film unit 41.

The sensor element 48 is fixed on the film portion 41 by a connecting portion 49 formed of a bonding material such as an adhesive. The output signal of the sensor element 48 is transmitted to an electric circuit (not shown) built in the in-cylinder pressure sensor 10 by a cable (not shown) connected to the sensor element 48.

The housing 11, the membrane 30, the heat receiving plate 31, the displacement member 34, the connecting member 35, and the diaphragm 40 of the in-cylinder pressure sensor 10 are joined in the following order, for example. First, the connecting member 35 is inserted into the inside of the first tubular portion 42 from the tip end side of the diaphragm 40, and then the diaphragm 40 and the connecting member 35 are connected by the fifth welded portion 45.

Separately from this, after the membrane 30 provided with the displacement member 34 is brought into contact with the tip facing surface 21 of the cap portion 13, the membrane 30 is joined to the cap portion 13 by the first welded portion 32. Next, the heat receiving plate 31 is joined to the membrane 30 by the third welded portion 33. The displacement member 34 is inserted into the connecting member 35, the rear end portion 23 of the cap portion 13 is abutted against the second overhanging portion 44, and then the displacement member 34 and the connecting member 35 are joined by the fourth welded portion 37. Finally, the cap portion 13 and the second overhanging portion 44 are joined by the second welded portion 46, and then the shaft portion 12 and the second overhanging portion 44 are joined by the sixth welded portion 47.

In the in-cylinder pressure sensor 10, when the screw portion 14 is tightened in the screw hole 101 of the engine 100 (see FIG. 1), the tapered surface 16 of the cap portion 13 is pressed against the contact surface 102 (see FIG. 1) of the engine 100. The tip surface 20 of the cap portion 13 and the heat receiving plate 31 are exposed to the combustion chamber 103. Axial force is applied to the cap portion 13 due to the tightening of the screw portion 14.

In the in-cylinder pressure sensor 10, when the membrane 30 is bent by receiving the pressure (in-cylinder pressure) of the combustion chamber 103, the displacement member 34 is displaced in the axial direction. The displacement of the displacement member 34 is transmitted to the first cylinder portion 42 of the diaphragm 40 via the connecting member 35. Since the second overhanging portion 44 provided on the second tubular portion 43 of the diaphragm 40 is fixed to the housing 11, mechanical strain is generated in the film portion 41 due to the axial displacement of the first tubular portion 42. The sensor element 48 generates an output signal according to the amount of mechanical strain of the film unit 41. The electric circuit (not shown) built in the in-cylinder pressure sensor 10 calculates the in-cylinder pressure based on the output signal of the sensor element 48.

As shown in FIG. 3, the inner peripheral surface 24 of the cap portion 13 connecting the rear end portion 23 of the cap portion 13 and the tip facing surface 21 is located closer to the axis O (see FIG. 2) toward the tip side. A plurality of steps are formed. In the present embodiment, the first stage 25 and the second stage 26 are formed in order from the rear end side. The first stage 25 is the stage closest to the second welded portion 46, and the second stage 26 is a stage located on the tip side next to the first stage 25. The first stage 25 and the second stage 26 are planes perpendicular to the axis O. The radial length of the rear end portion 23 of the second portion 22 on the rear end side of the first stage 25 is shorter than the radial length of the tapered surface 16.

The inner peripheral surface of the rear end portion 23 is in contact with the outer peripheral surface of the second tubular portion 43 of the diaphragm 40. As a result, when joining the cap portion 13 to the diaphragm 40, the second tubular portion 43 of the diaphragm 40 is fitted to the rear end portion 23 of the cap portion 13, the cap portion 13 is fixed to the diaphragm 40, and then the second overhang is extended. A second welded portion 46 can be formed between the portion 44 and the rear end portion 23. Since the cap portion 13 can be positioned and fixed using the diaphragm 40 before welding, the diaphragm 40 and the cap portion 13 can be easily welded by the second welding portion 46.

FIG. 4 is a cross-sectional view of the cap portion 13. FIG. 4 shows the portion shown by III in FIG. The inner peripheral surface 24a shown in FIG. 4 is a virtual surface when the second stage 26 is omitted, and the inner peripheral surface 24b is a virtual surface when the first stage 25 is omitted. When the cap portion 13 is manufactured so as to have the inner peripheral surface 24a, the cap portion 13 becomes thicker in the radial direction, so that the heat of the membrane 30 or the heat receiving plate 31 heated by the combustion gas is after the cap portion 13. It is easily transmitted to the end portion 23, and is easily affected by heat on the sensor element 48 (see FIG. 2) and the like. When the cap portion 13 is manufactured so as to have the inner peripheral surface 24b, the cap portion 13 becomes thinner in the radial direction, so that the mechanical strength of the cap portion 13 decreases. On the other hand, by forming the first stage 25 and the second stage 26 on the inner peripheral surface 24 of the cap portion 13, the heat conduction and mechanical strength of the cap portion 13 can be appropriately adjusted.

It will be described back to FIG. In the cross section including the axis O, the line segment 28 is the length of the straight line perpendicular to the tapered surface 16 cut out by the corner formed on the inner peripheral surface 24 of the cap portion 13 by the second step 26 and the tapered surface 16. Is the shortest. The base 27 of the second stage 26 is a point shared by the line segment 28 and the inner peripheral surface 24. The position of the intersection 18 of the tapered surface 16 and the cylindrical surface 17 of the cap portion 13 is closer to the tip side than the position of the base 27 of the second step 26. Further, in the cross section including the axis O, the length L1 of the line segment 28 is shorter than the length L2 of the tapered surface 16.

FIG. 5 is a cross-sectional view of the cap portion 13. FIG. 5 shows the portion shown by III in FIG. The tapered surface 16a shown in FIG. 5 is a virtual line segment parallel to the tapered surface 16. The position of the intersection 18a between the tapered surface 16a and the cylindrical surface 17 is on the rear end side of the position of the base 27 of the second stage 26. The radial distance L3 between the base 27 of the second stage 26 and the outer peripheral surface (cylindrical surface 17) is the radial distance L4 between the base 27 of the second stage 26 and the outer peripheral surface (tapered surface 16a). Longer than. The distance L3 is the length of the line segment perpendicular to the axis O among the line segments connecting the base 27 and the cylindrical surface 17. The distance L4 is the length of the line segment 29 perpendicular to the axis O among the line segments connecting the base 27 and the tapered surface 16a.

The cap portion 13 has the base 27 of the second stage 26 and the outer peripheral surface (cylindrical surface 17) as compared with the case where the intersection 18a is located on the rear end side of the base 27 of the second stage 26 (distance L4). Since the radial distance L3 between the two can be increased, the cross-sectional area of the cap portion 13 at the base 27 of the second stage 26 can be increased accordingly. Since the base 27 of the second stage 26 is a portion whose shape changes, stress concentration is likely to occur and it is likely to be a starting point of fracture. However, since the stress is reduced by increasing the cross-sectional area at the base 27, the strength of the cap portion 13 can be improved.

As shown in FIG. 3, the membrane 30 is bonded to the first portion 19 by the first welded portion 32, and the membrane 30 is covered with the heat receiving plate 31, so that the membrane 30 is from the combustion chamber 103 (see FIG. 1). Heat is transferred from the membrane 30 to the first part 19. When the cross-sectional area of the cap portion 13 at the base 27 of the second stage 26 becomes large, heat is easily transferred from the first portion 19 to the second portion 22 of the cap portion 13.

In the in-cylinder pressure sensor 10, since the length L1 of the line segment 28 passing through the base 27 of the second stage 26 and intersecting the tapered surface 16 perpendicularly is shorter than the length L2 of the tapered surface 16, the first part 19 to the second part The path through which heat is transferred from the tapered surface 16 of the first part 19 to the engine 100 is wider than the path through which heat is transferred to 22. Therefore, the heat transferred from the membrane 30 to the first portion 19 of the cap portion 13 can be easily transferred from the tapered surface 16 of the first portion 19 to the engine 100 (see FIG. 1), and the second portion 22 of the cap portion 13 can be easily transferred. It can be difficult to move to. As a result, it is possible to make it difficult to transfer heat to the diaphragm 40 joined to the second portion 22, so that the heat effect of the sensor element 48 arranged on the diaphragm 40 can be suppressed. Therefore, the accuracy of pressure detection by the sensor element 48 can be ensured.

The second embodiment will be described with reference to FIG. In the first embodiment, the case where the first stage 25 and the second stage 26 of the cap portion 13 are planes perpendicular to the axis O has been described. On the other hand, in the second embodiment, the case where the first stage 61 and the second stage 62 of the cap portion 51 are conical surfaces will be described. In the in-cylinder pressure sensor 50 in the second embodiment, a cap portion 51 is arranged in place of the cap portion 13 of the in-cylinder pressure sensor 10 in the first embodiment. The parts described in the first embodiment are designated by the same reference numerals, and the following description will be omitted. FIG. 6 is a cross-sectional view of the in-cylinder pressure sensor 50. FIG. 6 is a cross-sectional view including the axis O (see FIG. 2), and the portion shown by III in FIG. 2 is shown.

The cap portion 51 is a cylindrical member in which a conical tapered surface 52 whose diameter increases toward the rear end and a cylindrical surface 53 connected to the rear end side of the tapered surface 52 are formed on the outer peripheral surface. Since the angle formed by the tapered surface 52 and the cylindrical surface 53 of the cap portion 51 is rounded, the intersection 54 between the straight line extending the tapered surface 52 and the straight line extending the cylindrical surface 53 is referred to as the tapered surface 52. The intersection point 54 with the cylindrical surface 53 is set. The cap portion 51 includes a first portion 55 on the front end side from the position of the intersection 54 and a second portion 58 on the rear end side from the position of the intersection 54.

The cap portion 51 includes an annular tip surface 56 connected to the tip side of the tapered surface 52, and an annular tip facing surface 57 located inside the tip surface 56 in the radial direction and on the rear end side of the tip surface 56. I have. The membrane 30 arranged on the tip facing surface 57 is joined to the first portion 55 by the first welded portion 32. The rear end portion 59 of the second portion 58 is joined to the second overhanging portion 44 of the diaphragm 40 (see FIG. 2) by the second welded portion 46.

On the inner peripheral surface 60 of the cap portion 51 that connects the rear end portion 59 of the cap portion 51 and the tip facing surface 57, a plurality of steps located closer to the axis O (see FIG. 2) toward the tip side are formed. ing. In the present embodiment, the first stage 61 and the second stage 62 are formed in order from the rear end side. The first stage 61 is the stage closest to the second welded portion 46, and the second stage 62 is a stage located on the tip side next to the first stage 61. The first stage 61 and the second stage 62 are conical surfaces whose diameters are reduced toward the tip side.

The base 63 of the second step 62 has the longest length of the line segments formed by the second step 62 on the inner peripheral surface 60 of the cap portion 51 and the tapered surface 52 cuts a straight line perpendicular to the tapered surface 52. It refers to a point shared by the short line segment 64 and the inner peripheral surface 60. The position of the intersection 54 between the tapered surface 52 and the cylindrical surface 53 of the cap portion 51 is closer to the tip side than the position of the base 63 of the second step 62. As a result, the radial distance between the base 63 of the second stage 62 and the cylindrical surface 53 is longer than that of the case where the position of the intersection 54 is on the rear end side of the position of the base 63 of the second stage 62. Therefore, the cross-sectional area of the cap portion 51 at the base 63 of the second stage 62 can be increased. As a result, the strength of the cap portion 51 can be improved as in the first embodiment.

Since the first stage 61 and the second stage 62 are conical surfaces whose diameters are reduced toward the tip side, in the cross section including the axis O, the inner peripheral surface 60 is formed at the base 63 of the second stage 62 and the base 61a of the first stage 61. The angle of formation can be obtuse. As a result, the stress concentration at the base 63 of the second stage 62 and the base 61a of the first stage 61 can be relaxed, so that the strength of the cap portion 51 can be further improved.

Further, the length L1 of the line segment 64 is shorter than the length L2 of the tapered surface 52. Since the corner formed by the tapered surface 52 and the tip surface 56 of the cap portion 51 is also rounded, the intersection 65 and the intersection 54 between the straight line extending the tapered surface 52 and the straight line extending the tip surface 56 The distance L2 between them is defined as the length L2 of the tapered surface 52. As a result, the heat transferred from the membrane 30 to the first portion 55 of the cap portion 51 can be easily transferred from the tapered surface 52 of the first portion 55 to the engine 100 (see FIG. 1), while the second portion 58 of the cap portion 51. It can be difficult to move to. As a result, it is possible to make it difficult to transfer heat to the diaphragm 40 joined to the second portion 58, so that the thermal influence of the sensor element 48 arranged on the diaphragm 40 can be suppressed as in the first embodiment.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily inferred.

In the embodiment, the case where the first steps 25, 61 and the second steps 26, 62 are formed on the inner peripheral surfaces 24, 60 of the cap portions 13, 51 has been described, but the present invention is not necessarily limited to this. Of the inner peripheral surfaces 24, 60 of the cap portions 13, 51, it is naturally possible to form one or more stages between the second stages 26, 62 and the tip surfaces 20, 56.

In the embodiment, of the inner peripheral surfaces 24, 60 of the cap portions 13, 51, the portion between the first stage 25, 61 and the second stage 26, 62, and the second stage 26, 62 and the tip facing surface. The case where the portion between the parts 21 and 57 is a cylindrical surface, that is, the case where these portions are parallel to the axis O in the cross section including the axis O has been described. However, it is not always limited to this. Of course, it is possible to make at least one of these sites a conical surface that shrinks in diameter toward the tip. In this case as well, the same effects as those of the first embodiment and the second embodiment can be realized.

In the embodiment, the case where the membrane 30 is bonded to the tip facing surfaces 21 and 57 of the cap portions 13 and 51 has been described, but the present invention is not necessarily limited to this. Of course, it is possible to omit the tip facing surfaces 21 and 57 and join the membrane 30 to the tip surfaces 20 and 56 of the cap portions 13 and 51 by the first welded portion 32.

In the embodiment, the case where the cylindrical connecting member 35 is arranged between the displacement member 34 and the diaphragm 40 that transmit the deformation of the membrane 30 to the rear end side of the housing 11, is not necessarily limited to this. It's not a thing. The shape of the connecting member 35 can be set arbitrarily.

In the embodiment, the case where the connecting member 35 is arranged between the displacement member 34 and the diaphragm 40 has been described, but the present invention is not necessarily limited to this. Of course, it is possible to omit the connecting member 35 and directly join the diaphragm 40 to the displacement member 34.

In the embodiment, the case where the diaphragm 40 in which the cylindrical first cylinder portion 42 and the second cylinder portion 43 are connected to the annular film portion 41 to which the sensor element 48 is fixed is used has been described, but the present invention is not necessarily limited to this. It is not something that can be done. Of course, it is possible to omit the first cylinder portion 42 and the second cylinder portion 43 and use a diaphragm made of a circular film portion (disk). In this case, the outer edge of the circular diaphragm is joined to the second portions 22, 58 of the cap portions 13, 51 by the second welded portion 46. The rod-shaped or tubular displacement member that is displaced in the axial direction as the membrane 30 is deformed is arranged so as to transmit a force to the center of the diaphragm. The sensor element 48 is arranged at a portion of the diaphragm where the strain is large. The number of sensor elements 48 to be arranged on the diaphragm is appropriately set.

In the embodiment, the case where the first welded portion 32 and the second welded portion 46 are formed by laser welding has been described, but the present invention is not necessarily limited to this. Of course, it is possible to form the welded portion by another joining method. Other joining methods include, for example, electron beam welding.

In the embodiment, the case where the point-shaped third welded portion 33 is formed at the center of the heat receiving plate 31 has been described, but the present invention is not necessarily limited to this. Of course, it is possible to make the third weld 33 into another shape such as an annular shape. Further, in the embodiment, the case where the heat receiving plate 31 covering the membrane 30 is arranged has been described, but the present invention is not necessarily limited to this. Of course, it is possible to omit the heat receiving plate 31.

In the second embodiment, the angle formed by the tapered surface 52 and the cylindrical surface 53 and the angle formed by the tapered surface 52 and the tip surface 56 of the cap portion 51 are rounded. How to obtain the length L2 of 52 has been described. Similarly, when the angle formed by the tapered surface 52 and the cylindrical surface 53 and the angle formed by the tapered surface 52 and the tip surface 56 are chamfered, the length L2 of the intersection 54 and the tapered surface 52 is set. Can be sought. Further, in the case where the angle formed by the tapered surface 16 and the cylindrical surface 17 and the angle formed by the tapered surface 16 and the tip surface 20 are rounded or chamfered in the first embodiment, the intersection 18 is similarly formed. And the length L2 of the tapered surface 16 can be obtained.

In the embodiment, the in-cylinder pressure sensors 10 and 50 having the conical tapered surfaces 16 and 52 have been described, but the present invention is not necessarily limited to this. Of course, it is possible to make the tapered surfaces 16 and 52 into a spherical band shape. Also in this case, the same effect as that of the in-cylinder pressure sensors 10 and 50 in the embodiment can be realized.

When the tapered surfaces 16 and 52 are spherical, the intersection of the tapered surface and the cylindrical surfaces 17 and 53 in the cross section including the axis O is a curve indicating the tapered surface among the points on the straight line indicating the cylindrical surfaces 17 and 53. It means the point of sharing one point of. That is, the intersection of the tapered surface and the cylindrical surfaces 17, 53 in the cross section including the axis O refers to the tip of a straight line indicating the cylindrical surfaces 17, 53.

Further, when the tapered surfaces 16 and 52 are spherical, the length L1 of the line segment that passes through the roots 27 and 63 of the second steps 26 and 62 in the cross section including the axis O and intersects the tapered surface perpendicularly is the tapered surface. The length of a line segment that intersects a tangent line perpendicularly. When the tapered surfaces 16 and 52 are spherical, the length L2 of the tapered surface is the length of the tapered surface that abuts on the contact surface 102 of the engine 100 along the tapered surface in the cross section including the axis O. Say that.

10,50 In-cylinder pressure sensor 13,51 Cap part 16,52 Tapered surface 17,53 Cylindrical surface 18,54 Intersection point 19,55 Part 1 22,58 Part 2 Part 24,60 Inner peripheral surface 25,61 1st stage ( The step closest to the second weld)
26,62 2nd stage (stage on the next tip side)
27,63 Root 28,64 Line segment 30 Membrane 32 1st weld 34 Displacement member 40 Diaphragm 46 2nd weld 48 Sensor element 100 Engine L1 Line segment length L2 Tapered surface length O-axis

Claims (2)

The diameter increases toward the rear end in the axial direction, and the tapered surface that comes into contact with the engine is connected to the cylindrical first portion formed on the outer peripheral surface and the rear end side in the axial direction of the first portion, and is connected to the tapered surface. A cap portion including a cylindrical second portion having a continuous cylindrical surface formed on the outer peripheral surface, and a cap portion.
A membrane that is joined to the first part via a first weld, closes the opening of the first part, and deforms in response to pressure.
A displacement member that is located at the rear end of the membrane, has a rod shape extending along the axis, and is displaced in the axial direction as the membrane is deformed.
A diaphragm that is joined to the second part via a second weld and deforms with the displacement of the displacement member.
An in-cylinder pressure sensor that is arranged on the diaphragm and includes a sensor element that outputs a signal based on the strain amount of the diaphragm.
On the inner peripheral surface of the cap portion, a plurality of steps located closer to the axis toward the tip side are formed.
In the cross section including the axis, the position of the intersection of the tapered surface and the cylindrical surface is the in-cylinder pressure on the tip side of the position of the base of the step on the next tip side from the step closest to the second welded portion. Sensor. The in-cylinder pressure sensor according to claim 1, wherein the length of a line segment that passes through the base of the step and intersects the tapered surface perpendicularly in the cross section including the axis is shorter than the length of the tapered surface.

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