JP5006695B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor suitable for use in a combustion pressure sensor for detecting the pressure in a combustion chamber of an internal combustion engine.

  Conventionally, a combustion pressure sensor (pressure sensor) that is attached to an engine (internal combustion engine) and detects the pressure of a combustion chamber is known, for example, in Patent Documents 1 to 3 and the like. Each of these types of pressure sensors is configured as a pressure sensor with a built-in amplifier. In the housing, there is at least a piezoelectric element that converts pressure into an electrical signal, and a circuit board that processes an electrical signal obtained from the piezoelectric element. And a lead for electrically connecting the piezoelectric element and the circuit board. The reason why the amplifier (circuit board) is built in the pressure sensor is that the electric signal obtained by the piezoelectric element of the pressure sensor is transmitted to the in-vehicle controller (in-vehicle computer) via the transmission cable, and the weak electric power transmitted by the transmission cable This is to avoid the problem of causing malfunction (false detection) due to disturbance noise superimposed on the signal, and in addition to avoiding the use of an expensive low noise cable that is not easily affected by noise.

On the other hand, this type of pressure sensor is exposed to a severe temperature environment that changes from a low temperature to a high temperature (about −40 to 350 ° C.). Therefore, when a circuit board is built in the pressure sensor, the pressure sensor can withstand these temperature environments. In particular, it is necessary to take measures to prevent disconnection of the joint portion (connection portion) due to thermal expansion and contraction. Therefore, in the conventional pressure sensor described above, the lead connecting the piezoelectric element and the circuit board is provided with a curved portion (folded portion) for absorbing thermal expansion and contraction, and an internal portion for releasing the displacement of the lead caused by thermal expansion and contraction. Space was secured.
JP-A-63-148137 Japanese Utility Model Sho 63-73648 JP-A-5-126667

  However, the conventional pressure sensor described above has the following problems.

  First, it is necessary to provide the lead with a curved part (bent part) for absorbing thermal expansion and contraction, and to secure an internal space for escaping the lead displacement caused by thermal expansion and contraction, which complicates the internal structure. This leads to a decrease in manufacturability, an increase in manufacturing man-hours, and a cost increase.

  Second, when a pressure sensor is attached to an engine, it is exposed not only to severe temperature environments but also to poor vibration environments, but it is necessary to secure an internal space for escaping the lead displacement. Unnecessary vibrations, that is, shaking and co-vibration other than transmitted vibrations are allowed. Therefore, the relative displacement of the lead due to unnecessary vibration may cause disconnection of the joint (connection portion), poor contact, and the like, and the reliability is not sufficient.

  An object of the present invention is to provide a pressure sensor that solves the problems in the background art.

  In order to solve the above-described problems, the present invention includes at least a piezoelectric element 3 that converts pressure into an electric signal, a circuit board portion 4 that processes an electric signal obtained from the piezoelectric element 3, and a piezoelectric element. When the pressure sensor 1 including the element 3 and the lead portion 5 that electrically connects the circuit board portion 4 is configured, the front housing portion using different materials is obtained by dividing the housing 2 into at least front and rear portions. The substrate housing chamber 11 is provided in the rear housing portion 2r, the circuit board portion 4 is housed in the substrate housing chamber 11, and the lead portion 5 is linear. It is formed by a pin member 5p having a circular cross section, one end 5s side of the lead part 5 is penetrated through the circuit board part 4, and the circuit board part 4 is in contact with the circuit board part 4s on the opposite side. In addition, the other end 5t of the lead portion 5 is connected to the electrode portion 6 on the piezoelectric element 3 side accommodated in the front housing portion 2f via a coil spring 7c which is a compressed conductive elastic member 7, and a circuit. The substrate storage chamber 11 that stores the substrate portion 4 is filled with an insulating filler 12.

  In this case, according to a preferred aspect of the invention, a stainless steel material can be used for the front housing portion 2f, and a carbon steel component U forged, press-molded or casted by a carbon steel material is used for the rear housing portion 2r. be able to. The filler 12 can contain at least one or more synthetic resins having rigidity when solid, rubber or synthetic resin having elasticity when solid, and one or more ceramic powders having insulation properties when solid. The pressure sensor 1 can be applied to a combustion pressure sensor 1s that detects the pressure in the combustion chamber Mr of the internal combustion engine M.

  According to the pressure sensor 1 according to the present invention having such a configuration, the following remarkable effects can be obtained.

  (1) The lead part 5 is formed by a linear pin member 5p, and the one end 5s side of the lead part 5 is passed through the circuit board part 4 and connected to the circuit board part 4 on the opposite side of the circuit board part 4. At the same time, the other end 5t of the lead portion 5 is connected to the electrode portion 6 on the piezoelectric element 3 side through the compressed elastic member 7 having conductivity, so that the bending for absorbing thermal expansion and contraction provided in the lead portion 5 is performed. It is not necessary to secure an internal space for escaping the portion (folded portion) or its displacement, and it is possible to improve manufacturability, reduce manufacturing man-hours, and reduce manufacturing costs by simplifying the internal structure.

  (2) Since it is not necessary to secure a curved portion (bent portion) for absorbing thermal expansion and contraction provided in the lead portion 5 and an internal space for escaping the displacement, it is possible to prevent the lead portion 5 from being adversely affected by the vibration environment. Can do. Therefore, it is possible to avoid disconnection of the joint (connection part) due to vibration, poor contact, etc., and to greatly improve the reliability. The pressure sensor 1 according to the present invention can control the pressure of the combustion chamber Mr of the internal combustion engine M. It is optimal for use in the combustion pressure sensor 1s to be detected.

  (3) The housing 2 is divided into at least two parts in the front and rear, and is configured by a combination of the front housing part 2f and the rear housing part 2r using different materials. For example, the affected temperature environment and various parts arranged inside Therefore, it is possible to select an optimal material for each of the above, and it is possible to improve performance, improve reliability, and further contribute to cost reduction.

  (4) Since the coil spring 7 c is used as the elastic member 7, it is possible to reliably absorb the relative displacement of the lead portion 5 due to expansion and contraction while ensuring the linearity and balance of the lead portion 5.

  (5) Since the substrate housing chamber 11 is provided in the housing 2 and the insulating material 12 is filled in the substrate housing chamber 11 in which the circuit board portion 4 is housed, the circuit board portion 4 corresponding to the use environment is provided. Protection can be strengthened.

  (6) According to a preferred embodiment, if a stainless steel material is used for the front housing portion 2f and a carbon steel part U forged, press-molded or casted by a carbon steel material is used for the rear housing portion 2r, the pressure sensor 1 is used. The tip portion (detection head portion) can be constructed to withstand a high temperature environment, and the manufacturing cost of the rear housing portion 2r having a complicated shape that is difficult to cut can be reduced. In addition, while ensuring the moldability of the rear housing part 2r, it is an optimal housing from the viewpoints of heat resistance, mechanical strength, bondability (waterproofness) between the front housing part 2f and the rear housing part 2r, and reduction of effects on thermal expansion and contraction. 2 can be obtained.

  (7) According to a preferred embodiment, the filler 12 includes at least one or more synthetic resins having rigidity when solid, rubber or synthetic resin having elasticity when solid, and ceramic powder having insulation properties when solid. In addition, it is possible to ensure vibration resistance (vibration absorption), heat resistance (heat dissipation), waterproofness (moisture resistance), insulation, and the like according to the usage environment, and to obtain a synergistic effect thereof.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of the pressure sensor 1 according to the present embodiment will be specifically described with reference to FIGS.

  The overall appearance configuration of the pressure sensor 1 is shown in FIGS. The pressure sensor 1 includes a detection head portion 51, a mounting screw portion 52, a tool locking portion 53, and a connector portion 54 from the front side, and is entirely covered by the housing 2 except for the detection head portion 51 and the connector portion 54. .

  Therefore, the pressure sensor 1 having such a configuration can be used as a combustion pressure sensor 1s for detecting the pressure (combustion pressure) of the combustion chamber Mr of the internal combustion engine (engine) M as shown in FIG. In FIG. 7, reference numeral 61 denotes an engine cylinder, 62 denotes an engine piston, 63 denotes a spark plug, and the pressure sensor 1 can be attached to a cylinder head 61 h of the engine cylinder 61. In this case, at the time of attachment, the attachment screw portion 52 of the pressure sensor 1 is screwed into the screw hole portion formed through the cylinder head 61 h and is fastened and fixed by the tool engaged with the tool locking portion 53. As a result, the detection head portion 51 faces the inside of the combustion chamber Mr, and the combustion pressure of the combustion chamber Mr acts on the detection head portion 51. The connector unit 54 is connected to an in-vehicle controller (in-vehicle computer) 65 through a transmission cable 66.

  On the other hand, FIG. 3 shows the overall internal structure of the pressure sensor 1. The housing 2 is configured by a combination of a front housing part 2f and a rear housing part 2r which are divided into two parts in the front and rear directions. In this case, the front housing part 2f is manufactured by using a material that can withstand at least the use temperature environment of −40 to 350 [° C.] in order to constitute the detection head part 51 facing the inside of the high temperature combustion chamber Mr. Specifically, it is desirable to use a stainless steel material having high heat resistance, for example, JIS: SUS630, JIS: SUS316 or the like. Both SUS630 and SUS316 have sufficient heat resistance and mechanical strength, but SUS316 is slightly inferior to SUS630 in mechanical strength, so SUS630 is the best material to use for the front housing part 2f. is there.

  On the other hand, since the rear housing part 2r is not directly exposed to the combustion chamber Mr, heat resistance is not questioned more than the front housing part 2f. However, since the rear housing part 2r has a complicated shape that is not easy to cut and increases the amount of use, the carbon steel part U that is forged, press-formed, or cast from a carbon steel material in consideration of cost. It consists of. As the carbon steel material, for example, JIS: S20C, JIS: S25C or the like is preferably used. S20C and S25C can be forged, press-molded or casted, and are advantageous in terms of cost. In addition, it has necessary heat resistance and mechanical strength, and can be welded to the above-described SUS630, so that necessary joining properties (waterproofness) can be ensured. S20C was used for the illustrated rear housing part 2r.

  As described above, the housing 2 is divided into the front and rear parts, and is configured by combining the front housing part 2f and the rear housing part 2r using different materials. Therefore, there is an advantage that an optimum material can be selected for each of the above-mentioned relationships, thereby contributing to performance improvement, reliability improvement, and cost reduction. In particular, since a stainless steel material is used for the front housing portion 2f and a carbon steel component U forged, press-molded, or cast with a carbon steel material is used for the rear housing portion 2r, the tip portion (detection head portion) of the pressure sensor 1 is used. Can be constructed to withstand a high temperature environment, and the manufacturing cost of the rear housing part 2r having a complicated shape that is not easy to cut can be reduced. In addition, while ensuring the moldability of the rear housing portion 2r, the housing is optimal from the viewpoints of heat resistance, mechanical strength, jointability (waterproofness) between the front housing portion 2f and the rear housing portion 2r, and reduction of effects on thermal expansion and contraction. 2 can be obtained.

  1 and 2 show an enlarged view of the detection head portion 51 including the front housing portion 2f. The front housing part 2f is formed in a cylindrical shape as a whole, and the piezoelectric element 3 and the electrode part 22 are accommodated in the front part, and the diaphragm head 21 is fixed to the front end part of the front housing part 2f. The diaphragm head 21 is formed by integrally forming a diaphragm portion 21d to which pressure acts, a flange portion 21f that forms a peripheral portion of the diaphragm head 21, and a transmission portion 21t that is provided on the rear surface of the diaphragm portion 21d. The diaphragm head 21 is made of an alloy diaphragm having high elasticity and excellent durability, heat resistance, and touch resistance. After the diaphragm head 21, a piezoelectric element 3 that converts pressure acting on the diaphragm portion 21d into an electric signal is disposed. For the piezoelectric element 3, for example, a langate (LTG), preferably a langate single crystal material already proposed by the present applicant (see Japanese Patent Application Laid-Open No. 2006-250711) can be used. The transmission portion 21t also serves as one electrode portion that is in surface contact with the front surface of the piezoelectric element 3. The other electrode portion 22 is disposed after the piezoelectric element 3. The electrode portion 22 integrally includes an element-side electrode portion 22s that is in surface contact with the rear surface of the piezoelectric element 3 and a protruding lead-side electrode portion 6 that protrudes on the opposite side. A donut-shaped insulating ring 24 formed of alumina ceramics or the like is fitted into the electrode portion 22 (electrode portion 6). Thereby, the electrode part 6 is accommodated in the center hole of the insulating ring 24, and the insulating ring 24 is provided with a spring accommodating recess 26 into which one end of a coil spring 7c (elastic member 7) to be described later enters.

  Further, a cylindrical insulating pipe 27 is accommodated in the rear portion of the front housing portion 2f. The insulating pipe 27 has a lead insertion hole 28 through which a front portion 5f of the lead portion 5 described later is inserted. The intermediate portion of the front housing portion 2f functions as a stopper for the insulating ring 24 and the insulating pipe 27, and provides a small-diameter insertion hole to allow the spring accommodating recess 26 and the lead insertion hole 28 to communicate with each other. Reference numeral 29 denotes an elastic body interposed between the rear end portion of the insulating pipe 27 and the front housing portion 2f.

  On the other hand, as shown in FIG. 3, the rear housing portion 2r is formed in a cylindrical shape as a whole, and is provided with a mounting screw portion 52 on the outer peripheral surface of the front portion and a tool locking portion 53 on the outer peripheral surface of the rear portion. And the rear end of the front housing part 2f mentioned above is joined to the front end of the rear housing part 2r. Further, the tool locking portion 53 is formed to have a relatively large diameter, and the substrate housing chamber 11 is provided therein, and a connector portion 54 is attached to the rear end of the rear housing portion 2r to close the substrate housing chamber 11. Note that the tool locking portion 53 may be a hexagonal shape similar to that of the bolt head, for example, as long as a tightening tool is locked. The shape of the tool locking portion 53 depends on other shapes. Can be replaced.

  On the other hand, a guide pipe 31 made of Teflon (registered trademark) is accommodated in the mounting screw portion 52 which is the front portion of the rear housing portion 2r. The guide pipe 31 has a lead insertion hole 32 through which an intermediate part 5m of the lead part 5 described later is inserted. Further, the substrate housing chamber 11 houses the circuit board portion 4 that processes (amplifies) an electric signal obtained from the piezoelectric element 3. As shown in FIG. 4, the circuit board portion 4 is a printed wiring board, and a plurality of electronic components 35... Are mounted on the printed wiring board and three plug pins 37 a, 37 b, extending into the connector portion 54. 37c is joined and configured.

  A lead portion 5 is connected to the center of the circuit board portion 4. For this reason, the circuit board portion 4 has a lead insertion hole 36 through which the one end 5s of the lead portion 5 is inserted (penetrated). The lead portion 5 is integrally formed by a linear pin member 5p having a circular cross section, and extends from the front end of the intermediate portion 5m, an intermediate portion 5m inserted into the lead insertion hole 32 of the guide pipe 31, and the intermediate portion. The front part 5f is inserted into the insulating pipe 27 by being formed with a smaller diameter than the part 5m, and the rear part 5r is extended from the rear end of the intermediate part 5m and formed with a larger diameter than the intermediate part 5m. As a material of the lead part 5, brass, beryllium copper, or the like can be used. In this case, brass is desirable in consideration of workability and cost merit. On the other hand, beryllium copper is desirable in view of electrical conductivity, high temperature strength, reliability, and the like.

  Moreover, 7c is a coil spring which comprises the elastic member 7, and uses the coil spring made from an alloy which is highly elastic and excellent in durability, heat resistance, touch resistance and the like. Therefore, this coil spring 7c can use the same material as the diaphragm head 21 mentioned above. The coil spring 7c selects a length that can be interposed between the electrode portion 6 and the other end 5t (front portion 5f) of the lead portion 5 in a compressed state, and the diameter of the front portion 5f of the lead portion 5 is selected. Select the same or slightly smaller diameter.

  On the other hand, the connector portion 54 includes a connector base portion 41 that is integrally formed of an insulating material such as alumina ceramics and that has a front end portion inserted into the rear end of the rear housing portion 2r (substrate housing chamber 11) to close the rear end. . The connector base portion 41 constitutes the connector portion 54 by passing through the three plug pins 37a, 37b, 37c described above and projecting into the connector base portion 41.

  Next, a method for assembling the pressure sensor 1 having such a structure will be described with reference to FIGS.

  First, the detection head unit 51 is assembled. In this case, as shown in FIG. 1, the insulating ring 24 and the electrode portion 22 are accommodated from the front end of the front housing portion 2 f and the piezoelectric element 3 is accommodated. And the flange part 21f of the diaphragm head 21 is fixed to the front end of the front housing part 2f by welding. In addition, the insulating pipe 27 is accommodated in the interior from the rear end of the front housing portion 2f, and the elastic body 29 is accommodated, and crimping is performed by a crimping portion 30 integrally formed at the rear end of the front housing portion 2f. Then, as shown in FIG. 3, the coil spring 7 c is accommodated inside the insulating pipe 27. As a result, the front end of the coil spring 7 c is accommodated in the spring accommodating recess 26. Thereafter, a rear housing part 2r accommodating the guide pipe 31 is prepared, and the front end of the rear housing part 2r is fitted to the rear end of the front housing part 2f and fixed by welding.

  On the other hand, a separately manufactured circuit board portion 4 is prepared. As described above, a plurality of electronic components 35 and three plug pins 37a, 37b, and 37c are mounted on the circuit board portion 4. Moreover, the lead part 5 is prepared, and as shown in FIG. 4, the rear part 5r (one end 5s) of the lead part 5 is inserted into the lead insertion hole 36 of the circuit board part 4 from the back surface 4r side to the front surface 4f side. Make it protrude slightly. Then, a predetermined wiring pattern on the rear portion 5r of the lead portion 5 and the surface 4f side is connected by soldering or the like.

  If the circuit board part 4 to which the lead part 5 is connected is obtained, the lead part 5 is inserted from the board housing chamber 11 into the lead insertion hole 32 of the guide pipe 31, and the front part 5f of the lead part 5 (the other end 5t). To the lead insertion hole 28 of the insulating pipe 27 and the circuit board portion 4 is accommodated in the substrate accommodating chamber 11 and set at a predetermined position. Thereby, the coil spring 7c is interposed in a compressed state between the tip surface of the electrode portion 6 and the other end 5t of the lead portion 5, and the electrode portion 6 and the lead portion 5 are electrically connected via the coil spring 7c. .

  In addition, the substrate housing chamber 11 is filled with an insulating filler 12. Thereby, as shown in FIG. 3, the internal space from the substrate housing chamber 11 to the guide pipe 31 is filled with the filler 12. By filling the filler 12, it is possible to enhance protection of the circuit board portion 4 corresponding to the use environment. The filler 12 may contain one or more synthetic resins having rigidity when solid, rubber or synthetic resin having elasticity when solid, and ceramic powder having insulation properties when solid. As the synthetic resin having rigidity when solid, for example, an epoxy resin can be used, and as the rubber or synthetic resin having elasticity when solid, for example, a polyurethane resin or the like can be used. Furthermore, in an aspect in which two or more individual fillers are included, a rubber or synthetic resin having elasticity when solid is applied to the entire circuit board portion 4 in advance to provide a coating layer having a certain thickness. A mode in which a synthetic resin having rigidity is sometimes filled or a mode in which a synthetic material of synthetic resin and ceramic powder (placera) is used is included. By appropriately using such a filler 12, vibration resistance (vibration resistance), heat resistance (heat dissipation), waterproofness (moisture resistance), insulation, etc. can be ensured according to the use environment, and the synergistic effect of these. An effect can also be obtained.

  Next, an elastic body 42 such as an elastic ring is attached to the connector base 41 and inserted into the rear end of the rear housing 2r. At this time, the three plug pins 37a, 37b, 37c are passed through the insertion holes provided in the connector base 41. Then, the connector base 41 is fixed to the rear end of the rear housing part 2r by caulking the caulking part 43 formed integrally with the rear end of the rear housing part 2r. As a result, the substrate housing chamber 11 is closed, and the connector portion 54 to which the transmission cable 66 can be connected is obtained.

  Next, the usage method and operation | movement of the pressure sensor 1 which concern on this embodiment are demonstrated with reference to FIGS.

  As described above, since the pressure sensor 1 can be used as the combustion pressure sensor 1s, it can be attached to an engine M such as an automobile to detect the combustion pressure as shown in FIG. When the pressure sensor 1 is attached to the engine M, the attachment screw portion 52 of the pressure sensor 1 is screwed into the screw hole portion of the cylinder head 61h, and is fastened and fixed by a tool locked to the tool locking portion 53.

  On the other hand, when the engine 11 is operated, pressure (combustion pressure) is applied to the diaphragm portion 21 d of the diaphragm head 21. As a result, the electric charge generated in the piezoelectric element 3 due to the pressure acting on the piezoelectric element 3 sandwiched between the electrode part (transmission part) 21t and the electrode part 22 becomes the electrode part 6, the coil spring 7c, and the lead part 5. Is applied to the circuit board part 4 via Then, predetermined processing (amplification processing) is performed on a weak electric signal by the circuit board unit 4, and is given to the in-vehicle controller (in-vehicle computer) 65 through the connector unit 54 and the transmission cable 66.

  In this case, since the pressure sensor 1 is attached to the engine M such as an automobile, it is usually exposed to a severe temperature environment (temperature fluctuation) of about −40 to 350 [° C.]. Therefore, the lead portion 5 repeats relative displacement with respect to the housing 2 due to thermal expansion and contraction of the housing 2, particularly the rear housing 2 r and the lead portion 5. In FIG. 8, the length of the lead portion 5 at normal temperature is Ls, the length of the lead portion 5 at high temperature is Lm, the length of the rear housing 2r at normal temperature is Hs, and the length of the rear housing 2r at high temperature is Assuming that the height is Hm, the relative displacement width K of the coil spring 7c is K = (Lm−Ls) − (Hm−Hs). The maximum is about 0.06 [mm]. In FIG. 8, Po indicates a fixed end of the pressure sensor 1.

  Further, when the pressure sensor 1 described above is attached to the engine M, tightening is performed from a tool. The axial force at this time is 12 [kN] at the maximum, and when tightened by the maximum axial force, the housing 2 is It has been confirmed that the pressure sensor 1 is shortened by about 150 [μm] with respect to the tip of the pressure sensor 1.

  On the other hand, the allowable displacement of the illustrated coil spring 7c is 1.32 [mm], and the above-described displacement width K (about 0.06 [mm]) and shortening due to tightening (about 150 [μm]) are considered. However, the expansion and contraction of the lead portion 5 can be sufficiently absorbed by the coil spring 7c. By using such a coil spring 7c for the elastic member 7, it is possible to reliably absorb the relative displacement of the lead part 5 due to stress reduction and thermal expansion and contraction while ensuring the linearity and balance of the lead part 5. it can.

  Therefore, according to such a pressure sensor 1 according to the present embodiment, the lead portion 5 is formed by the linear pin member 5p, the one end 5s side of the lead portion 5 is passed through the circuit board portion 4, and the circuit In order to connect to the circuit board part 4 on the opposite side of the board part 4, and to connect the other end 5t of the lead part 5 to the electrode part 6 on the piezoelectric element 3 side via a compressed conductive elastic member 7. In addition, it is not necessary to secure a curved part (bent part) for absorbing thermal expansion and contraction provided in the lead part 5 and an internal space for escaping the displacement, improving the manufacturability by reducing the internal structure, reducing the number of manufacturing steps, and manufacturing. Cost can be reduced. Further, since it becomes unnecessary to secure a curved portion (folded portion) for absorbing thermal expansion and contraction provided in the lead portion 5 and an internal space for escaping the displacement, it is possible to prevent an adverse effect on the lead portion 5 due to the vibration environment. it can. Therefore, it is possible to avoid disconnection of the joint (connection part) due to vibration, contact failure, and the like, and to greatly improve reliability.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and departs from the gist of the present invention in the detailed configuration, shape, material, quantity, numerical value, and the like. It can be changed, added, or deleted as long as it is not.

  For example, the configuration (form) in the whole or details of the pressure sensor 1 can be arbitrarily configured as long as it includes the main configuration of the present invention. Further, the materials used for the piezoelectric element 3, the coil spring 7c, the front housing portion 2f, the rear housing portion 2r, the lead portion 5 and the like are not limited to the examples, and can be appropriately selected.

  The pressure sensor 1 is optimally used as a combustion pressure sensor 1s for detecting the pressure of the combustion chamber Mr of the internal combustion engine M, as shown in the example. It can be used as a pressure sensor for various applications in other fields such as an environment with large vibrations.

Sectional side view which shows the internal structure of the detection head part in the pressure sensor which concerns on the best embodiment of this invention, XX sectional view in FIG. Sectional side view showing the internal structure of the pressure sensor, A partial cross-sectional side view showing components used for the main part configuration of the pressure sensor, External side view of the pressure sensor, Exterior view of the pressure sensor, The block diagram which shows the state which attached the same pressure sensor to the engine, Action diagram of the pressure sensor,

Explanation of symbols

  1: pressure sensor, 1s: combustion pressure sensor, 2: housing, 2f: front housing part, 2r: rear housing part, 3: piezoelectric element, 4: circuit board, 5p: pin member, 5s: one end of lead, 5t: The other end of the lead, 6: electrode portion, 7: elastic member, 7c: coil spring, 11: substrate housing chamber, 12: filler, M: internal combustion engine, Mr: combustion chamber, U: carbon steel parts

Claims (5)

  In the housing, at least a piezoelectric element that converts pressure into an electric signal, a circuit board part that processes an electric signal obtained from the piezoelectric element, and a lead part that electrically connects the piezoelectric element and the circuit board part In this pressure sensor, the housing is divided into at least two parts in the front-rear direction to form a combination of a front housing part and a rear housing part using different materials, and a substrate housing chamber is provided in the rear housing part. The circuit board portion is housed in the substrate housing chamber, the lead portion is formed by a linear cross-sectional pin member, and one end side of the lead portion is passed through the circuit board portion, and An elastic member having a conductive property that is connected to the circuit board part on the opposite side of the circuit board part and the other end of the lead part is compressed. It is connected to the electrode part on the piezoelectric element side accommodated in the front housing part via a coil spring, and the substrate accommodation chamber containing the circuit board part is filled with an insulating filler. Pressure sensor.   The pressure sensor according to claim 1, wherein the front housing portion uses a stainless steel material.   The pressure sensor according to claim 1 or 2, wherein the rear housing portion uses a carbon steel part that is forged, press-molded, or cast from a carbon steel material.   The filler includes at least one or more synthetic resins having rigidity when solid, rubber or synthetic resin having elasticity when solid, and one or more ceramic powders having insulation properties when solid. The pressure sensor according to 2 or 3.   The pressure sensor according to claim 1, wherein the pressure sensor is applied to a combustion pressure sensor that detects a pressure in a combustion chamber of an internal combustion engine.

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