JP2017201277A - Intra-cylinder pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intra-cylinder pressure sensor with which it is possible to suppress an intra-cylinder pressure transmitted to a sensor element at abnormal combustion time.SOLUTION: An intra-cylinder pressure sensor 20 comprises a housing 21, a body 22, a diaphragm 30, a sensor element 51 and a force transmission member 55. The intra-cylinder pressure sensor 20 includes a seal 60 for sealing a gap between a cylinder head 10 and itself when fitted to the cylinder head 10, the seal 60 being formed in annular form so as to enclose the outer circumferential surface of the diaphragm 30 and the outer circumferential surface of the body 22 all around in the circumferential direction. The distance between the inner circumferential surface of the seal 60 and the outer circumferential surface of the diaphragm 30 and outer circumferential surface of the body 22 is set to such a distance that a flame occurring due to combustion in a combustion chamber 16 of an internal combustion engine propagates to the outer circumferential surface of the body 22 at abnormal combustion time due to occurrence of preignition or knocking and does not propagate to the outer circumferential surface of the body 22 at normal combustion time that is not the abnormal combustion time.SELECTED DRAWING: Figure 1

Description

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

  The in-cylinder pressure sensor described in Patent Document 1 has a cylindrical housing and a body connected to one end of the housing. The body has a bottomed cylindrical shape, and is arranged so that the end on the housing side becomes the bottom and the end opposite to the housing becomes the opening. A flexible diaphragm is fixed to the opening of the body. The diaphragm bends in response to the in-cylinder pressure that is the pressure in the combustion chamber. The in-cylinder pressure received by the diaphragm is transmitted to the bottom of the body through a force transmission member disposed inside the body. A sensor element is fixed to the bottom. The sensor element is distorted together with the bottom due to the in-cylinder pressure transmitted to the bottom, and the output signal is changed according to the amount of distortion. That is, the sensor element outputs a signal corresponding to the in-cylinder pressure. A signal from the sensor element is output to a detection unit provided in the in-cylinder pressure sensor. The detection unit detects the in-cylinder pressure based on a signal from the sensor element.

JP 2008-70190 A

  When abnormal combustion such as preignition or knocking occurs in the combustion chamber, excessive pressure acts on the in-cylinder pressure sensor. In the in-cylinder pressure sensor described in Patent Document 1, since the sensor element is distorted according to the in-cylinder pressure, the amount of distortion may be excessive during abnormal combustion. In order to improve the durability of the sensor element, it is desirable to suppress the in-cylinder pressure transmitted to the sensor element during abnormal combustion.

  An in-cylinder pressure sensor for solving the above problems includes a cylindrical housing, a body fixed to one end portion of the housing and having a through-hole penetrating in the axial direction of the housing, and the housing in the body A diaphragm that is fixed to an end opposite to the side and closes one end of the through hole, a sensor element that is housed in the housing and changes an output signal in accordance with pressure, and the body of the body A cylinder pressure sensor that is inserted through the through-hole, has one end connected to the sensor element, and the other end connected to the diaphragm, and is assembled to the cylinder head, A seal that seals a gap with the cylinder head, and the seal surrounds the outer peripheral surface of the diaphragm and the outer peripheral surface of the body over the entire circumference. The distance between the inner peripheral surface of the seal and the outer peripheral surface of the diaphragm and the outer peripheral surface of the body is such that a flame generated by combustion in the combustion chamber of the internal combustion engine causes preignition and knocking. The distance is set to a distance that does not propagate to the outer peripheral surface of the body during normal combustion but not during abnormal combustion.

  In the above configuration, the gap between the seal, the diaphragm and the body is set so that the flame does not propagate to the outer peripheral surface of the body in normal combustion, and the flame propagates to the outer peripheral surface of the body in abnormal combustion where the in-cylinder pressure increases. Yes. Therefore, at the time of abnormal combustion, the flame generated by the combustion can be propagated to the outer peripheral surface of the body, and the body can be thermally expanded. Due to the thermal expansion of the body, the diaphragm is displaced in the axial direction of the housing, and the distance between the diaphragm and the sensor element is increased. Thereby, a part of the displacement when the diaphragm is bent by the in-cylinder pressure is absorbed between the force transmission member and the diaphragm, and the pressure acting on the sensor element is suppressed. Therefore, according to the said structure, the cylinder pressure transmitted to a sensor element at the time of abnormal combustion can be suppressed.

Sectional drawing which shows typically the structure of one Embodiment of a cylinder pressure sensor. Sectional drawing which expands and shows the peripheral part of the seal | sticker of a cylinder pressure sensor. Sectional drawing which shows typically the propagation aspect of the flame at the time of abnormal combustion. Sectional drawing which shows typically the propagation aspect of the flame at the time of normal combustion. Sectional drawing which expands and shows the peripheral part of the seal | sticker in other embodiment of a cylinder internal pressure sensor. Sectional drawing which shows the state of the seal | sticker at the time of abnormal combustion in the same embodiment. Sectional drawing which shows typically the structure in other embodiment of a cylinder pressure sensor.

An embodiment of an in-cylinder pressure sensor will be described with reference to FIGS.
As shown in FIG. 1, the cylinder head 10 of the internal combustion engine is provided with an attachment hole 11 to which the in-cylinder pressure sensor 20 is attached. The attachment hole 11 communicates with the combustion chamber 16 of the internal combustion engine and is formed in a substantially cylindrical shape. The attachment hole 11 has a small-diameter chamber 12 that communicates with the combustion chamber 16 and a tapered chamber 13 that communicates with the small-diameter chamber 12. The taper chamber 13 is formed in a shape whose diameter is increased as it is separated from the small-diameter chamber 12 side. A medium diameter chamber 14 communicates with the taper chamber 13. The diameter of the medium diameter chamber 14 is larger than the diameter of the small diameter chamber 12. A large-diameter chamber 15 communicates with the medium-diameter chamber 14. The diameter of the large-diameter chamber 15 is larger than the diameter of the medium-diameter chamber 14. A female screw 15 </ b> A is formed on the inner peripheral surface of the large-diameter chamber 15.

  The cylinder internal pressure sensor 20 has a cylindrical housing 21. A male screw 21 </ b> A is formed on the outer peripheral surface of the housing 21. The male screw 21 </ b> A of the housing 21 is screwed into the female screw 15 </ b> A of the large diameter chamber 15. Thereby, the in-cylinder pressure sensor 20 is assembled to the cylinder head 10.

  A body 22 is fixed to one end of the housing 21 on the combustion chamber 16 side (upper side in FIG. 1). The body 22 is made of a metal such as SUS304. The body 22 has a main body portion 23 that is in contact with an end surface of one end portion of the housing 21, and an extending portion 24 that extends from the main body portion 23 toward the inside of the housing 21 in a cylindrical shape. . The main body portion 23 is formed with a through hole 25 extending through the main body portion 23 in the axial direction of the housing 21 (the vertical direction in FIG. 1). The through hole 25 communicates with the inside of the extension part 24. The end portion of the main body portion 23 on the combustion chamber 16 side constitutes a reduced diameter portion 27 that is reduced in diameter compared with the enlarged diameter portion 26 that is the end portion of the main body portion 23 on the housing 21 side (lower side in FIG. 1). doing. In the main body 23, the enlarged diameter portion 26 and the reduced diameter portion 27 are connected by an inclined portion 28 whose diameter is increased toward the enlarged diameter portion 26 side. In the cross section shown in FIG. 1, the inclined surface 28 </ b> A that is the outer peripheral surface of the inclined portion 28 extends in parallel with the opposing wall surface 13 </ b> A of the tapered chamber 13.

  The body 22 is provided with a diaphragm 30 on the end surface of the reduced diameter portion 27. The outer diameter of the reduced diameter portion 27 and the outer diameter of the diaphragm 30 are the same, and the outer peripheral surface of the reduced diameter portion 27 and the outer peripheral surface of the diaphragm 30 are flush with each other. The diaphragm 30 and the body 22 are fixed to each other by, for example, welding the outer peripheral surface over the entire circumference. The diaphragm 30 is made of a material having a smaller linear expansion coefficient than the material constituting the body 22, for example, a metal such as SUS630.

  The diaphragm 30 closes one end of the through hole 25 of the body 22. The diaphragm 30 includes a flexible portion 31 having flexibility and a peripheral portion 32 that is connected to the periphery of the flexible portion 31 and abuts against the end surface of the body 22. The flexible portion 31 is displaced to the housing 21 side with respect to the peripheral portion 32, the transmission portion 33 constituting the central portion of the diaphragm 30, and the shoulder portion 34 connecting the transmission portion 33 and the peripheral portion 32. It consists of. The shoulder portion 34 has a convex curved shape on the combustion chamber 16 side. When the diaphragm 30 is thermally expanded by the combustion heat in the combustion chamber 16, the relative position of the transmission portion 33 in the diaphragm 30 may shift to the housing 21 side. The shape of the shoulder portion 34 is set in advance so that the relative position of the transmission portion 33 does not change when the diaphragm 30 is thermally expanded. That is, by setting the length and thickness of the shoulder portion 34, the displacement of the transmission portion 33 toward the housing 21 during thermal expansion of the diaphragm 30 is absorbed by the displacement of the shoulder portion 34 toward the combustion chamber 16 side. The relative position of the transmission unit 33 is prevented from shifting.

  A counter member 40 is provided inside the housing 21. The facing member 40 has a columnar insertion portion 41 and a cylindrical tube portion 42 erected on the end surface of the insertion portion 41 opposite to the combustion chamber 16 side. The cylinder portion 42 extends in a direction away from the diaphragm 30. The outer diameter of the insertion part 41 and the cylinder part 42 is the same. The cylindrical portion 42 is formed with a locking portion 42A that protrudes outward from the outer peripheral surface. The locking portion 42A is fixed to the end surface of the extending portion 24 of the body 22, for example, by welding. The insertion portion 41 is inserted into the extension portion 24 of the body 22, and the outer peripheral surface thereof is in contact with the inner peripheral surface of the extension portion 24. The insertion part 41 and the cylinder part 42 are made of, for example, metal such as SUS630, and are configured as an integrated object. A housing chamber 50 is constituted by the end surface of the facing member 40 on the diaphragm 30 side, the inner peripheral surface of the body 22, and the end surface of the diaphragm 30 on the housing 21 side.

  A sensor element 51 is accommodated in the accommodation chamber 50. One end surface of the sensor element 51 is fixed to the insertion part 41 of the facing member 40 and is located inside the extension part 24. Therefore, it can be said that the sensor element 51 is accommodated in the housing 21. The sensor element 51 is made of, for example, an intrinsic semiconductor, and the resistance value changes according to pressure. The sensor element 51 is connected to a pair of terminals 53 via a pair of lead wires 52. Each terminal 53 extends in the axial direction of the housing 21 through the insertion portion 41 of the opposing member 40 and is formed in an elongated shape. Each terminal 53 is connected to a circuit portion (not shown) of the in-cylinder pressure sensor 20. The circuit unit is provided with a constant current circuit and a detection circuit. A constant current is supplied to the sensor element 51 through the constant current circuit. Therefore, when pressure acts on the sensor element 51 and the resistance value of the sensor element 51 changes, the voltage generated between the pair of lead wires 52 changes. A detection signal corresponding to this voltage is output to the detection circuit.

  A glass block 56 is fixed to the other end surface of the sensor element 51 on the combustion chamber 16 side, for example, by anodic bonding. A first rod 57 is fixed to the glass block 56. The first rod 57 is formed in a hemispherical shape having a curved top surface opposite to the glass block 56 side. One end of the second rod 58 is connected to the top surface of the first rod 57. The second rod 58 is inserted through the through hole 25 of the body 22. The other end of the second rod 58 is connected to the transmission portion 33 of the diaphragm 30. The second rod 58 has a shape in which the contact surface with the diaphragm 30 is curved. The 1st rod 57 and the 2nd rod 58 have heat insulation, for example, are constituted from ceramics. The glass block 56, the first rod 57, and the second rod 58 constitute a force transmission member 55. That is, the force transmission member 55 is inserted into the through hole 25 penetrating the body 22 in the axial direction of the housing 21, and one end is connected to the sensor element 51 and the other end is connected to the diaphragm 30.

  The in-cylinder pressure, which is the pressure in the combustion chamber 16, acts on the diaphragm 30 through the small diameter chamber 12 and the tapered chamber 13 of the attachment hole 11. When the in-cylinder pressure acts on the diaphragm 30, the flexible portion 31 bends toward the housing 21 side. As a result, pressure acts on the sensor element 51 from the transmission portion 33 via the second rod 58, the first rod 57, and the glass block 56. A signal from the sensor element 51 is output to the detection circuit, and the cylinder pressure is detected by the detection circuit.

  The in-cylinder pressure sensor 20 is also provided with a seal 60 that seals a gap with the cylinder head 10 when assembled to the cylinder head 10. The seal 60 has elasticity and is made of a metal such as SUS630. The seal 60 is formed in an annular shape so as to surround the outer peripheral surface of the diaphragm 30 and the outer peripheral surface of the body 22 over the entire circumferential direction. As shown in FIG. 2, the seal 60 includes one end portion 61 that is in contact with the body 22 and the other end portion 62 that is in contact with the cylinder head 10. One end surface 61 </ b> A on the body 22 side in the one end portion 61 is inclined along the inclined surface 28 </ b> A of the body 22. Therefore, the seal 60 and the body 22 are in surface contact. Further, the other end 62 of the seal 60 is rounded inward in the radial direction. The other end 62 formed by rounding is easily elastically deformed. The seal 60 is sandwiched between the inclined surface 28 </ b> A of the body 22 and the wall surface 13 </ b> A of the tapered chamber 13. In this state, the other end portion 62 of the seal 60 which is rounded is held in a state of being elastically deformed by being pressed in the axial direction. Therefore, the seal 60 is pressed against the wall surface 13 </ b> A of the taper chamber 13 by the reaction force of the other end 62. As a result, the seal 60 prevents the gas flowing from the combustion chamber 16 into the mounting hole 11 from flowing outward in the radial direction from the seal 60.

  The seal 60 is provided such that the inner peripheral surface 63 thereof is separated from the outer peripheral surface of the diaphragm 30 and the outer peripheral surface of the reduced diameter portion 27 of the body 22. Further, the seal 60 is provided such that the outer peripheral surface thereof is separated from the wall surface 13 </ b> A of the taper chamber 13 and the wall surface of the medium diameter chamber 14.

  The flame when the combustion gas burns in the combustion chamber 16 propagates from the combustion chamber 16 into the mounting hole 11. The distance D between the inner peripheral surface 63 of the seal 60 and the outer peripheral surface of the diaphragm 30 and the outer peripheral surface of the body 22 indicates that the flame generated by combustion in the combustion chamber 16 of the internal combustion engine is abnormally burned due to the occurrence of pre-ignition or knocking. The distance is set to a distance that does not propagate to the outer peripheral surface of the body 22 during normal combustion, which is not during abnormal combustion, while sometimes propagating to the outer peripheral surface of the body 22. In the seal 60, the inner peripheral surface of the one end portion 61 and the innermost peripheral portion of the other end portion 62 are in the same position in the radial direction, and the inner peripheral surface 63 of the seal 60 is configured by these. When the flame propagates through the gap between the seal 60 and the diaphragm 30 and the body 22, heat is taken away by the seal 60, the diaphragm 30 and the body 22. Therefore, the smaller the distance D is, the more difficult the flame propagates. On the other hand, assuming that the distance D is constant even if combustion heat is applied, the higher the in-cylinder pressure, the easier it is for the flame to propagate through the gap between the seal 60, the diaphragm 30 and the body 22. The distance D can be obtained in advance by experiments and simulations based on this viewpoint, and is set to 0.1 mm, for example.

With reference to FIG.3 and FIG.4, the effect of this embodiment is demonstrated.
As indicated by solid arrows in FIG. 3, the flame generated by the combustion propagates from the combustion chamber 16 to the mounting hole 11 of the cylinder head 10. In the attachment hole 11, the flame propagates from the combustion chamber 16 side toward the in-cylinder pressure sensor 20 side. In the present embodiment, the distance D between the seal 60 and the diaphragm 30 and the body 22 is set between the inner peripheral surface 63 of the seal 60 and the outer peripheral surface of the body 22 at the time of abnormal combustion when the in-cylinder pressure increases. Is set to propagate. Therefore, as indicated by solid line arrows in FIG. 3, during abnormal combustion, the flame propagates between the inner peripheral surface 63 of the seal 60 and the outer peripheral surface of the body 22. As a result, the body 22 directly receives the combustion heat and thermally expands. Due to the thermal expansion of the body 22, the diaphragm 30 is displaced toward the combustion chamber 16 (upper side in FIG. 3) in the axial direction of the housing 21. As a result, the distance between the diaphragm 30 and the sensor element 51 is increased. When the distance between the diaphragm 30 and the sensor element 51 is increased, a part of the displacement when the diaphragm 30 is bent by the in-cylinder pressure at the time of abnormal combustion is between the first rod 57 and the second rod 58, Absorbed between the two rods 58 and the diaphragm 30. Thereby, the pressure which acts on the sensor element 51 is suppressed. Therefore, according to the present embodiment, the in-cylinder pressure transmitted to the sensor element 51 during abnormal combustion can be suppressed.

  Further, in the present embodiment, the distance D between the seal 60 and the diaphragm 30 and the body 22 is such that flames generated by combustion during normal combustion do not propagate between the inner peripheral surface 63 of the seal 60 and the outer peripheral surface of the body 22. The distance is set. Therefore, as indicated by solid arrows in FIG. 4, the flame propagating through the mounting hole 11 during normal combustion is extinguished without propagating between the inner peripheral surface 63 of the seal 60 and the outer peripheral surface of the body 22. . Thereby, combustion heat is not directly transmitted to the body 22, and thermal expansion of the body 22 is suppressed. Although heat is transmitted to the diaphragm 30 by the propagation of the flame, as described above, the displacement of the transmitting portion 33 when the diaphragm 30 is thermally expanded can be suppressed by adapting the shape of the shoulder portion 34. ing. Thus, in this embodiment, the change in the distance between the diaphragm 30 and the sensor element 51 during normal combustion is suppressed. Therefore, according to the present embodiment, the in-cylinder pressure can be accurately transmitted to the sensor element 51 via the force transmission member 55 during normal combustion.

  Further, the body 22 is made of a material having a large linear expansion coefficient as compared with the linear expansion coefficient of the material constituting the diaphragm 30. Therefore, the amount of thermal expansion of the body 22 during abnormal combustion is larger than when the linear expansion coefficient of the material constituting the body 22 is equal to the linear expansion coefficient of the material constituting the diaphragm 30. Therefore, according to this embodiment, the amount of displacement of the diaphragm 30 in the axial direction during abnormal combustion can be increased.

The above embodiment can be implemented with the following modifications.
-The structure of a seal is not restricted to what was mentioned above. For example, the configuration shown in FIG. 5 may be adopted. In the configuration shown in FIG. 5, configurations similar to those in the above embodiment are denoted by common reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, the seal 70 is sandwiched between the body 22 and the cylinder head 10. The seal 70 includes one end portion 71 that is in contact with the body 22 and the other end portion 72 that is in contact with the cylinder head 10. One end surface 71 </ b> A of the one end portion 71 of the seal 70 that contacts the inclined portion 28 of the body 22 is inclined along the inclined surface 28 </ b> A of the inclined portion 28. Therefore, the seal 70 and the body 22 are in surface contact. The inner peripheral surface 71B of the one end portion 71 is formed in a tapered shape so as to be positioned radially outward as the combustion chamber 16 side (upper side in FIG. 5) in the axial direction of the housing 21 (vertical direction in FIG. 5). . Therefore, the area of the inner peripheral surface 71B of the seal 70 is larger than that of the above embodiment. Note that the distance between the inner peripheral surface 71B of the seal 70 and the outer peripheral surface of the diaphragm 30 and the outer peripheral surface of the body 22 increases toward the combustion chamber 16 side. This distance is such that a flame generated by combustion in the combustion chamber 16 of the internal combustion engine propagates to the outer peripheral surface of the body 22 at the time of abnormal combustion due to the occurrence of pre-ignition or knocking, while the body 22 at the time of normal combustion not at the time of abnormal combustion. It is set to a distance that does not propagate to the outer peripheral surface of. That is, the distance D1 in the radial direction between the end surface of the reduced diameter portion 27 of the body 22 and the inner peripheral surface 71B of the seal 70 indicates that the flame generated by combustion during the normal combustion is further on the housing 21 side (lower side in FIG. 5). Is set not to propagate to The other end 72 of the seal 70 is rounded inward in the radial direction.

  As indicated by the white arrow in FIG. 6, the in-cylinder pressure acts on the inner peripheral surface 71 </ b> B of the seal 70. In the above configuration, since the pressure receiving area of the seal 70 is larger than that of the above embodiment, the deformation amount of the seal 70 when receiving the in-cylinder pressure is large. That is, as shown by a solid line in FIG. 6, at the time of abnormal combustion with high in-cylinder pressure, the seal 70 is pushed radially outward and elastically deformed compared to the state at the time of normal combustion (two-dot chain line in FIG. 6). . Thereby, the distance between the inner peripheral surface 71B of the seal 70 and the outer peripheral surface of the body 22 is increased. As the distance between the inner peripheral surface 71B of the seal 70 and the outer peripheral surface of the body 22 increases, the amount of heat of the flame propagated through this gap increases. Therefore, the amount of heat transmitted to the body 22 during abnormal combustion increases, and the amount of displacement of the diaphragm 30 in the axial direction can be increased. Therefore, even with such a configuration, an appropriate configuration can be realized in suppressing the in-cylinder pressure transmitted to the sensor element 51 during abnormal combustion.

  When the abnormal combustion is completed, the pressure that has been applied is released, so that the seal 70 returns to the state shown in FIG. During normal combustion, the in-cylinder pressure is lower than that during abnormal combustion. Therefore, even if the in-cylinder pressure acts on the seal 70, the seal 70 is not easily elastically deformed radially outward. Therefore, during normal combustion, the distance D1 between the end surface of the reduced diameter portion 27 of the body 22 and the inner peripheral surface 71B of the seal 70 is maintained, and the propagation of the flame to the outer peripheral surface of the body 22 is suppressed.

  As long as the seals 60 and 70 can be sandwiched between the body 22 and the cylinder head 10, the inclined surface 28A and the wall surface 13A of the tapered chamber 13 do not necessarily have to be parallel.

  In the above embodiment, the seals 60 and 70 are sandwiched between the body 22 and the cylinder head 10, but the seal may be sandwiched between the housing 21 and the cylinder head 10 as shown in FIG. 7. In this configuration, the body portion 23 of the body 22 is formed in a cylindrical shape whose outer diameter does not change in the axial direction of the housing 21 (the vertical direction in FIG. 7). The outer diameter of one end surface of the housing 21 on the combustion chamber 16 side is larger than the outer diameter of the main body 23 of the body 22. On one end face of the housing 21, one end 81 of the seal 80 is in contact with the outer side in the radial direction from the portion where the main body 23 of the body 22 is fixed. The other end 82 of the seal 80 is in contact with the wall surface 13 </ b> A of the tapered chamber 13 of the cylinder head 10. The gap with the cylinder head 10 can also be sealed by the seal 80 having such a configuration. Even in such a configuration, the distance between the inner peripheral surface 80A of the seal 80 and the outer peripheral surface of the diaphragm 30 and the outer peripheral surface of the body 22 is such that a flame generated by combustion in the combustion chamber 16 of the internal combustion engine The distance is set to a distance that does not propagate to the outer peripheral surface of the body 22 during normal combustion but not during abnormal combustion, while propagating to the outer peripheral surface of the body 22 during abnormal combustion due to the occurrence of ignition or knocking.

  If the gap with the cylinder head 10 can be sealed, the other end portions 62, 72, 82 of the seals 60, 70, 80 may not be rounded radially inward. For example, you may comprise so that the end surface of the other end parts 62, 72, and 82 and the wall surface 13A of the taper chamber 13 may surface-contact.

  The linear expansion coefficient of the material constituting the body 22 may be equal to the linear expansion coefficient of the material constituting the diaphragm 30 or may be smaller than the linear expansion coefficient of the material constituting the diaphragm 30.

  In the seal 60, the inner peripheral surface of the one end portion 61 and the innermost peripheral portion of the other end portion 62 are formed in the same position in the radial direction, but the configuration of the seal 60 is not limited to this. . That is, if the distance D can be set to a distance at which the flame generated by combustion propagates to the outer peripheral surface of the body 22 during abnormal combustion but does not propagate to the outer peripheral surface of the body 22 during normal combustion, The inner peripheral surface of one end portion 61 of 60 may be on the inner side or the outer side in the radial direction than the innermost peripheral portion of the other end portion 62.

  Although abnormal combustion and normal combustion are defined as combustion modes in the combustion chamber 16, abnormal combustion is due to knocking or pre-ignition, and normal combustion refers to other combustion excluding knocking and pre-ignition. Say.

  DESCRIPTION OF SYMBOLS 10 ... Cylinder head, 11 ... Mounting hole, 12 ... Small diameter chamber, 13 ... Tapered chamber, 13A ... Wall surface, 14 ... Medium diameter chamber, 15 ... Large diameter chamber, 15A ... Female thread, 16 ... Combustion chamber, 20 ... In-cylinder pressure sensor , 21 ... Housing, 21A ... Male screw, 22 ... Body, 23 ... Body part, 24 ... Extension part, 25 ... Through-hole, 26 ... Expanded part, 27 ... Reduced part, 28 ... Inclined part, 28A ... Inclined surface , 30 ... Diaphragm, 31 ... Flexible part, 32 ... Peripheral part, 33 ... Transmission part, 34 ... Shoulder part, 40 ... Opposing member, 41 ... Insertion part, 42 ... Tube part, 42A ... Locking part, 50 ... Accommodating Chamber 51 ... Sensor element 52 ... Lead wire 53 ... Terminal 55 ... Force transmission member 56 ... Glass block 57 ... First rod 58 ... Second rod 60 ... Seal 61 ... One end 61A ... One end face, 62 ... the other end, 63 ... an inner peripheral face, 70 ... a seal, 7 ... one end, 71A ... end surface, 71B ... inner peripheral surface, 72 ... the other end, 80 ... seal, 80A ... inner peripheral surface, 81 ... end, 82 ... the other end.

Claims (1)

A tubular housing;
A body that is fixed to one end of the housing and has a through-hole that penetrates in the axial direction of the housing;
A diaphragm that is fixed to an end of the body opposite to the housing and closes one end of the through hole;
A sensor element housed in the housing, the output signal of which changes according to pressure;
A cylinder pressure sensor having a force transmission member inserted through the through-hole of the body, having one end connected to the sensor element and the other end connected to the diaphragm;
Having a seal that seals the gap with the cylinder head when assembled to the cylinder head;
The seal is formed in an annular shape so as to surround the outer peripheral surface of the diaphragm and the outer peripheral surface of the body over the entire circumference in the circumferential direction.
The distance between the inner peripheral surface of the seal and the outer peripheral surface of the diaphragm and the outer peripheral surface of the body is such that the flame generated by combustion in the combustion chamber of the internal combustion engine is in the abnormal combustion due to the occurrence of pre-ignition or knocking. An in-cylinder pressure sensor that is set to a distance that does not propagate to the outer peripheral surface of the body during normal combustion but not during abnormal combustion.

Images