JP6231987B2 - Pressure detection device - Google Patents

Description

  The present invention relates to an electrical transmission means of a pressure detection device mounted on an engine or the like.

  Conventionally, for example, a pressure detection device using a piezoelectric element has been proposed in order to detect the pressure in a combustion chamber attached to an engine. When such a pressure detection device is attached to the tip of a functional member facing the combustion chamber of the engine, in order to extract an electrical signal (detection signal) from the piezoelectric element of the pressure detection device, the tip of the functional member, In addition, an electrical transmission means that extends and connects to a pressure detection device facing the combustion chamber of the engine is essential.

  As an electrical transmission means of this type, an insulating layer made of resin is formed around the conductor portion (center conductor), a shielding layer (outer conductor) made of, for example, a metal braid is formed around the insulating layer, and the shielding layer is further formed. A coaxial cable in which a protective layer made of a resin is formed around is known. In this cable structure, a coaxial cable formed by coating an electrolytic metal plating layer around an insulating layer instead of a metal braid is disclosed (for example, see Patent Document 1).

  In addition, a coaxial cable is disclosed in which an insulating coating made of resin is formed on the outer periphery of the central conductor, and a shield conductor is formed on the outer periphery of the insulating layer by electroless and / or electrolytic metal plating (see, for example, Patent Document 2).

  Furthermore, it is also conceivable to transmit an electrical signal to the outside using a flexible printed circuit board (hereinafter abbreviated as FPC) as an electrical transmission means of the pressure detection device.

JP 2007-48719 A JP 2005-149892 A

  By the way, a pressure detection device used in an engine or the like vibrates with a pressure change in the combustion chamber. And when such vibrations act on the electrical transmission means provided in the pressure detection device, in the coaxial cable as in the conventional example, the shielding layer formed by metal plating is cracked and peeled, resulting in As a result, noise is superimposed on the electrical signal from the coaxial cable, and in the worst case, the coaxial cable may be disconnected. In addition, in the connection using a coaxial cable or FPC, the position of the coaxial cable or FPC on the pressure detection device side and the electrode position on the external device side that receives a signal from the pressure detection device must be aligned and assembled. Since the mounting direction (circumferential mounting angle) is limited, there is a problem of poor workability.

  Further, the electrical transmission means connected to the pressure detection device facing the combustion chamber of the engine needs to extend and connect to the tip of the functional member through a slight gap inside the functional member. Therefore, since the conventional coaxial cable has a large diameter, there is a problem that it is difficult to pass such a small gap.

  An object of the present invention is to solve the above-mentioned problems, and to provide a pressure detection device that includes an electrical transmission means that is resistant to vibration and impact and can be easily mounted on the outer periphery of the tip of a functional member.

  In order to solve the above-described problem, a pressure detection device according to the present invention is a cylindrical pressure detection device configured to detect the internal pressure of a cylinder by being mounted on the outer periphery of the tip of a functional member facing the combustion chamber of the engine. A pressure receiving member that receives pressure from outside, a pressure transmission member that transmits pressure from the pressure receiving member, a piezoelectric element that abuts on the pressure transmission member to detect pressure fluctuations, and an electrode that abuts on the piezoelectric element A piezoelectric element that outputs an electrical signal corresponding to pressure from two opposing electrodes, and one electrode of the piezoelectric element abuts a casing that supports the piezoelectric element to become a ground electrode, and the other electrode Abuts against an electrode member provided between the pressure transmission member and the piezoelectric element, and the electrode member is electrically connected by an electrical transmission means via a connection terminal, and the electrical transmission means is an annular connection. The electrode Is characterized by transmitting electrical signals to the external device by the connection electrodes.

  In this case, according to a preferred aspect of the invention, one or a plurality of piezoelectric elements are arranged along the circumferential direction inside the casing, and the piezoelectric elements can be alternately arranged via spacers. On the other hand, the connection terminal can be connected to the electrical transmission means through a through hole provided in the spacer and the casing. In addition, it is desirable to interpose a spring between the connection terminal and the electrode member. Further, the connection electrode can be integrally provided with an elongated extension electrode extending from a predetermined portion of the electrode surface, and this extension electrode can be electrically connected to the tip of the connection terminal exposed from the through hole. On the other hand, the connection electrode may be provided with an electrode surface orthogonal to the center line of the housing, and the external electrode of the external device may be electrically connected to this electrode surface, or accommodated in the inner surface of the opening on the housing side. A cylindrical electrode surface may be provided, and an external electrode of the external device may be electrically connected to the electrode surface. When an electrode surface orthogonal to the center line of the housing is provided, claw portions can be formed at a plurality of locations on the outer periphery of the electrode surface and can be fixed to the housing side via the claw portions. Moreover, a cylindrical external electrode can be provided in the external device, and the electrode surface of the connection electrode can be electrically connected to the external electrode by soldering. On the other hand, when a cylindrical electrode surface to be accommodated in the inner surface of the opening on the housing side is provided, it can be electrically connected to the electrode surface by press-fitting an external electrode of an external device. In this case, a plurality of annularly arranged elastic electrodes can be provided on the electrode surface, and the elastic electrodes can be brought into contact with an external electrode of an external device to be electrically connected.

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

  (1) According to the present invention, since the electrical signal from the pressure detection device is directly transmitted to the external device side by the electrical transmission means formed of the annular connection electrode, it is not necessary to use a coaxial cable or FPC, and the external Since it can be reliably transmitted to the device, it is possible to provide a pressure detection device that is resistant to vibration and impact.

  (2) By using the connection electrode having an annular shape, the mounting direction of the pressure detection device is not limited, and the assembly of the device is facilitated, for example, it can be easily mounted on the outer periphery of the tip of the functional member. Furthermore, since it is possible to connect to the electrode on the external device side using the entire circumference of the connection electrode, it is possible to secure a large electrical connection area. As a result, the resistance value of the connection becomes extremely small, and a small level electric signal can be reliably obtained. It is possible to provide a pressure detection device with excellent reliability that can be transmitted to

  (3) According to a preferred embodiment, when a plurality of piezoelectric elements are arranged along the circumferential direction inside the housing, and the piezoelectric elements are alternately arranged via spacers, the pressure can be detected uniformly in a balanced manner, High-precision pressure detection is possible. On the other hand, even if there is only one piezoelectric element, it is possible to accurately and easily incorporate the arrangement position with the spacer formed in the C shape, and there is no loss with respect to the piezoelectric element. Pressure transmission is possible. Further, by balancing the stress, no chipping or cracking of the piezoelectric element occurs, and the cost can be reduced by reducing the number of piezoelectric elements.

  (4) According to a preferred embodiment, if the connection terminal is connected to the electrical transmission means through the spacer and the through hole provided in the housing, the connection terminal connected to the electrical transmission means is positioned and positioned. Can do. Moreover, a functional member such as a fuel injection device can be disposed in the opening in the cylindrical casing, and there is no need to secure an extra space for the pressure detection device.

  (5) If a spring is interposed between the connection terminal and the electrode member according to a preferred embodiment, even if the positional relationship between the connection terminal and the electrode member varies due to external pressure, the spring is connected to the electrode member by the spring force of the spring. The terminals can be securely connected electrically.

  (6) According to a preferred embodiment, the connection electrode is integrally provided with an elongated extension electrode extending from a predetermined portion of the electrode surface, and the extension electrode is electrically connected to the tip of the connection terminal exposed from the through hole. If the connection is made, the tip of the connection terminal can be directly connected to the extension electrode, so that an electrical signal from the piezoelectric element can be reliably transmitted to the connection electrode via the connection terminal.

  (7) According to a preferred embodiment, if the connection electrode is provided with an electrode surface orthogonal to the center line of the housing, and the external electrode of the external device is electrically connected to the electrode surface, Since the electrode surface can be provided in parallel to the end surface, the electrode dimension in the center line direction can be further reduced while ensuring a wide electrode area, thereby contributing to the downsizing of the pressure detection device.

  (8) According to a preferred embodiment, a plurality of claw portions are formed at a plurality of locations on the outer periphery of the electrode surface, and a plurality of connection electrodes are fixed to the housing side via the claw portions. Therefore, the connection electrode can be securely fixed.

  (9) According to a preferred aspect, if the electrode surface of the connection electrode is electrically connected to the cylindrical external electrode of the external device by soldering, an annular shape is formed with respect to the external electrode. The entire circumference of the connection electrode can be soldered. As a result, a large electrical connection area can be secured, resistance to vibration and impact, and the resistance value of the connection is small, so that a low-level electrical signal can be reliably transmitted to an external device. Moreover, the mounting direction of the pressure detection device is not limited, and the device can be easily assembled.

  (10) According to a preferred aspect, the connection electrode is provided with a cylindrical electrode surface accommodated in the inner surface of the opening on the housing side, and the external electrode of the external device is electrically connected to the electrode surface. For example, since the electrode surface can be provided by using the inner surface on the housing side, a wider electrical connection area can be secured. As a result, a structure that is resistant to vibrations and shocks can be obtained, and since the resistance value of the connection is small, a low-level electric signal can be reliably transmitted to the external device.

  (11) If the external electrode of the external device is press-fitted into the cylindrical electrode surface according to a preferred embodiment, press-fitting connection is possible, so that no soldering work is required. As a result, the number of assembly steps of the device can be reduced.

  (12) According to a preferred embodiment, a plurality of annularly arranged elastic electrodes are provided on a cylindrical electrode surface, and the elastic electrodes are brought into contact with and electrically connected to the external electrodes of the external device. Since the connection electrode and the electrode on the external device side are connected by a plurality of elastic electrodes, the soldering operation is unnecessary, and the number of assembly steps of the device can be reduced. In addition, since the entire circumference of the connection electrode is connected by the electrode on the external device side and the elastic electrode, a large electrical connection area can be secured, it is resistant to vibration and impact, and the resistance value of the connection is small. A level electric signal can be reliably transmitted to an external device.

It is a schematic block diagram of the engine with which the pressure detection apparatus of this invention is mounted | worn. It is sectional drawing along the centerline of the pressure detection apparatus of 1st Embodiment. It is the expanded sectional view which expanded the area | region A of sectional drawing of FIG. It is the expanded sectional view which expanded the area | region B of sectional drawing of FIG. It is a perspective view of the pressure detection apparatus of a 1st embodiment. It is a perspective view for demonstrating the connection electrode of 1st Embodiment. It is sectional drawing of the piezoelectric element vicinity which cut | disconnected the pressure detection apparatus of 1st Embodiment shown in FIG. 2 by the cutting line FF '. It is sectional drawing for demonstrating the example of mounting to the fuel-injection apparatus of the pressure detection apparatus of 1st Embodiment. It is a block diagram for demonstrating the pressure detection operation | movement of the pressure detection apparatus of 1st Embodiment. It is sectional drawing along the centerline of the pressure detection apparatus of 2nd Embodiment. It is a perspective view for demonstrating the connection electrode of 2nd Embodiment. It is sectional drawing along the centerline of the pressure detection apparatus of 3rd Embodiment. It is the rear view of the connection electrode simple substance which looked at the connection electrode of 3rd Embodiment from the back side of the pressure detection apparatus.

  1: engine, 2: cylinder block, 2a: cylinder, 4: cylinder head, 4a: communication hole, 4b: communication hole, 5: spark plug, 6: injector unit, 7: fuel injection device, 10: pressure detection device, 80: pressure detection device, 90: pressure detection device, 10a: opening, 11: front outer housing, 12: front inner housing, 13: rear housing, 13c: through hole, 14: pressure receiving ring, 15: pressure Transmission ring, 16: piezoelectric element group, 17: electrode member, 20 housing, 31: electrode connector, 81: electrode connector, 91: electrode connector, 32: connection electrode, 82: connection electrode, 92: connection electrode, 32a: Electrode surface, 82a: Electrode surface, 32b: Extension electrode, 82b: Extension electrode, 92b: Extension electrode, 32c: Claw part, 32d: Claw part, 32e: Claw part, 33: Connector housing, 5 : Connection terminal, 56: Coil spring, 71: Internal housing, 72: External housing, 75: External electrode, 76: Solder, 77: Amplifier circuit, 78: Control circuit, 82a: Press-fit electrode surface, 92a: Holding spring , 171 to 176: Spacer

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

  First, features of each embodiment will be described. A feature of the first embodiment is a pressure detection device that electrically connects a connection electrode having an annular electrode surface orthogonal to a center line of a housing to an electrode on an external device side by soldering. A feature of the second embodiment is a pressure detection device that electrically connects a connection electrode having a cylindrical press-fit electrode surface to an electrode on the external device side by press-fitting. A feature of the third embodiment is a pressure detecting device that is electrically connected by bringing a connection electrode having a plurality of elastic electrodes arranged in an annular shape into contact with an electrode on the external device side.

  First, a schematic configuration of an engine to which the pressure detection device according to the first to third embodiments of the present invention is mounted will be described with reference to FIG. In addition, although the example which mounts | wears with the pressure detection apparatus of 1st Embodiment is demonstrated here, the pressure detection apparatus of 2nd Embodiment and 3rd Embodiment which are mentioned later can also be mounted | worn similarly. In FIG. 1, reference numeral 1 denotes an engine to which the pressure detection device of the present invention is attached. The engine 1 includes a cylinder block 2 having a cylinder 2a, a piston 3 that reciprocates in the cylinder 2a, and a cylinder head 4 that is fastened to the cylinder block 2 and forms a combustion chamber C together with the cylinder 2a, the piston 3, and the like. I have.

  The engine 1 is mounted on the cylinder head 4 and ignites the fuel to explode the air-fuel mixture in the combustion chamber C. The engine 1 is mounted on the cylinder head 4 and injects fuel into the combustion chamber C. In addition, an injector unit 6 for detecting the pressure in the combustion chamber C is further provided. The cylinder head 4 is provided with two communication holes for communicating the combustion chamber C and the outside. One of the communication holes 4a has a spark plug 5 and the other communication hole 4b has an injector unit 6. Each is attached in a penetrating state.

  The injector unit 6 as a functional member for an engine is constituted by a fuel injection device 7 that injects fuel into the combustion chamber C, and a pressure detection device 10 that is a first embodiment of the present invention attached to the fuel injection device 7. To do. Here, the fuel injection device 7 includes a main body portion 7a disposed outside the combustion chamber C, and a columnar tip portion 7b extending from the main body portion 7a toward the combustion chamber C.

  On the other hand, the pressure detection device 10 has a function of detecting the internal pressure (combustion pressure: arrow D) in the combustion chamber C, and is attached to the outer periphery of the tip portion 7 b of the fuel injection device 7. And this pressure detection apparatus 10 is comprised by the cylindrical shape which has the opening part penetrated so that it may mention later.

First embodiment

  Next, the structure of the pressure detection apparatus 10 of 1st Embodiment is demonstrated using FIGS. 2 is a cross-sectional view in the center line direction of the pressure detection device 10 of the first embodiment, and FIGS. 3 and 4 are enlarged cross-sectional views of a region A and a region B shown in FIG. FIG. 5 is an external perspective view of the pressure detection device 10, and illustration of the connector housing 33 is omitted for explanation.

  In the following description, when the injector unit 6 is configured together with the fuel injection device 7, the side facing the combustion chamber C in the pressure detection device 10 is referred to as the “front side” and is opposite to the combustion chamber C. The facing side is referred to as the “back side”. In addition, a region A in FIG. 2 indicates a piezoelectric element peripheral region for detecting pressure, and a region B indicates a connection terminal peripheral region for transmitting an electric signal. The cutting line FF ′ in FIG. 2 will be described later.

  Here, the pressure detection device 10 has a cylindrical shape as a whole, and is provided with an opening 10a penetrating from the front side to the back side and accommodating the tip side of the tip portion 7b in the fuel injection device 7 shown in FIG. It has been. That is, the tip end portion 7b (indicated by a two-dot chain line in FIG. 2) of the fuel injection device 7 is accommodated in the opening 10a of the cylindrical pressure detection device 10. The details of the connection relationship between the pressure detection device 10 and the tip 7b of the fuel injection device 7 will be described later.

  The structure of the pressure detection device 10 includes a front outer casing 11 having a cylindrical shape and a cylindrical shape, and is disposed concentrically with the front outer casing 11 inside the front outer casing 11. A front inner housing 12 having a cylindrical shape, a rear housing 13 attached to the rear side of the front outer housing 11 and the front inner housing 12, and an annular shape and the front outer housing 11. And a pressure receiving ring 14 as a pressure receiving member that is attached to the front side of the front inner housing 12 and receives pressure from the outside.

  Further, an electrode connector 31 made of an insulating material having a cylindrical shape and incorporating a ring-shaped connection electrode 32 is disposed on the rear side of the rear housing 13, and further has a cylindrical shape, A connector housing 33 is provided that covers the entire circumference of the electrode connector 31 from the outside. In addition, in the region surrounded by the pressure receiving ring 14, the front outer casing 11, the front inner casing 12, and the rear casing 13, the pressure transmission ring 15, the piezoelectric element group 16, the connection terminal 52, and the like are arranged. A detailed description of each component will be described later.

  Next, details of the casing of the pressure detection device 10 will be described with reference to FIGS. As described above, the front outer casing 11 has a cylindrical shape, and a notch for fitting an outer end portion of a pressure receiving tip portion (described later) of the pressure receiving ring 14 into an inner end portion of the front surface side. 11a is formed (see FIGS. 3 and 4).

  As described above, the front inner casing 12 has a cylindrical shape, and the outer diameter thereof is smaller than the inner diameter of the front outer casing 11 described above. Further, a notch 12a for fitting the inner end portion of the pressure receiving tip portion of the pressure receiving ring 14 is formed on the outer side of the front end portion of the front inner housing 12 (see FIGS. 3 and 4). In addition, a notch 12b for fitting the inner side of the front side of the rear case 13 is formed on the outer side of the rear side of the front inner case 12 (see FIGS. 3 and 4).

  The rear housing 13 has a cylindrical shape, and includes a ground electrode layer 13b that functions as a ground electrode of the piezoelectric element group 16 on an end surface on the front surface side of the rear housing 13 (see FIG. 3). Here, the rear housing 13 has a front stage 131 that is set to have the same outer diameter as the inner diameter of the front outer casing 11 on the front surface side, and an outer diameter of the front outer casing 11 on the rear side of the front stage 131. It has a middle step 132 set to the same outer diameter, and a rear step 133 set to the same outer diameter as the inner diameter of the front outer casing 11 on the back side of the middle step 132 (see FIGS. 3 and 4).

  The ground electrode layer 13b described above is formed on the front end surface of the front stage 131 of the rear housing 13 over substantially the entire circumference. In addition, a notch 131a for fitting the outer end of the rear side of the front outer casing 11 is formed on the outer side of the front end of the front step 131 by the middle step 132 (FIGS. 3 and 3). 4). Further, the inner side of the front portion of the front stage 131 has a structure that is fitted into the notch 12b provided on the outer side of the rear side of the front inner housing 12 described above.

  Here, the front outer casing 11, the front inner casing 12, and the rear casing 13 are collectively referred to as a casing 20. Since the casing 20 is present at a position facing the combustion chamber C that can be at a high temperature or a position close to the combustion chamber C, the housing 20 is manufactured using a material that can withstand at least a temperature range of −40 ° C. to 350 ° C. It is desirable. Further, as will be described later, since the rear casing 13 is used as a grounding target of the piezoelectric element group 16, it is desirable that the rear casing 13 be manufactured using a conductive material. Specifically, the housing 20 may be configured using a stainless steel material having high heat resistance and conductivity, such as JIS standard SUS630, SUS316, SUS430, or the like.

  Then, laser welding is performed over the entire circumference in a state where the rear end of the front outer casing 11 is fitted into a notch 131a provided on the outer end of the front end of the rear casing 13. It is fixed with. Further, the notch 12b on the back side of the front inner housing 12 is fixed by laser welding over the entire circumference in a state of being fitted to the front surface side of the rear housing 13. As a result, the front outer casing 11 and the rear casing 13 are laser welded, and the front inner casing 12 and the rear casing 13 are laser welded to complete the integrated casing 20.

  Note that the ground electrode layer 13b provided on the end surface of the front portion 131 on the front surface side of the rear housing 13 is configured by laminating a single layer or a plurality of layers of a highly conductive metal thin film on the rear housing 13. . As such a ground electrode layer 13b, an inner layer using, for example, Ti as an adhesion strengthening layer is stacked on the rear casing 13, and an intermediate layer using, for example, Pt as a diffusion preventing layer is stacked on the inner layer. For example, a laminate in which a bonding layer using, for example, Au is stacked on the uppermost layer can be used.

  Next, the internal space formed in the housing 20 of the pressure detection device 10 will be described with reference to FIGS. 3 and 4. In the pressure detection device 10, a cylindrical inner space 10 b is formed in a region surrounded by the front outer casing 11, the front inner casing 12, the rear casing 13, and the pressure receiving ring 14 described above. The internal space 10b has an annular shape and is disposed on the back side of the pressure receiving ring 14, and a pressure transmission ring 15 as a pressure transmission member for transmitting the pressure from the pressure receiving ring 14 to the back side, and the pressure A piezoelectric element group 16 is provided between the back side of the transmission ring 15 and the end surface of the front stage 131 of the rear housing 13 and converts the pressure received from the pressure transmission ring 15 into an electrical signal. Details of the piezoelectric element group 16 will be described later.

  Next, details of the pressure receiving ring 14 will be described with reference to FIGS. 3 and 4. The pressure receiving ring 14 is provided so as to close an annular gap formed on the front side by the front outer casing 11 and the front inner casing 12 arranged concentrically. The pressure receiving ring 14 is exposed to the outside, that is, the combustion chamber C (see FIG. 1) side, thereby receiving a pressure receiving tip 14a that receives the internal pressure of the combustion chamber C of the cylinder 2a, and a pressure receiving tip on the back side of the pressure receiving tip 14a. The transmission portion 14b that transmits the pressure received by the portion 14a to the pressure transmission ring 15 is integrally formed. Then, the outer end of the pressure receiving tip 14a of the pressure receiving ring 14 is laser welded over the entire circumference in a state where it is fitted into a notch 11a provided inside the front end of the front outer casing 11. Is fixed.

  The inner end of the pressure receiving tip 14a of the pressure receiving ring 14 is laser welded over the entire circumference in a state where the inner end of the pressure receiving ring 14 is fitted into a notch 12a provided on the outer side of the front side of the front inner housing 12. Is fixed. And the transmission part 14b provided in the pressure receiving ring 14 is positioned with respect to both the inner peripheral surface of the front outer housing 11 and the outer peripheral surface of the front inner housing 12 so as not to contact both surfaces. The material constituting the pressure receiving ring 14 is made of an alloy having high elasticity and excellent durability, heat resistance, and corrosion resistance in consideration of being exposed to the combustion chamber C at high temperature and high pressure. For example, SUH660 or the like can be used.

  The pressure receiving ring 14 receives the combustion pressure from the combustion chamber C (arrow D in FIG. 3) by the pressure receiving tip portion 14a, and the combustion pressure D is transmitted to the pressure transmission ring 15 via the transmission portion 14b. It is transmitted to the piezoelectric element group 16 in contact with the ring 15 and converted into an electric signal described later.

  The pressure transmission ring 15 has an annular shape, and has a rectangular cross section. The outer diameter of the pressure transmission ring 15 is smaller than the inner diameter of the front outer casing 11, and the inner diameter is larger than the outer diameter of the front inner casing 12. . In addition, the pressure transmission ring 15 is good to comprise with ceramic materials, such as an alumina which has heat resistance and insulation.

  Further, an electrode member 17 that functions as an output electrode for outputting an electrical signal from the piezoelectric element group 16 is provided on the end surface on the back side of the pressure transmission ring 15. The electrode member 17 is annularly arranged on the end surface on the back side of the pressure transmission ring 15 over the entire circumference. That is, the electrode member 17 is provided between the pressure transmission ring 15 and the piezoelectric element group 16.

  As an example, the electrode member 17 includes an annular insulating film formed on one side of a highly conductive metal film that is a member different from the pressure transmission ring 15, and an end face on the back side of the pressure transmission ring 15 with an adhesive or the like. It is good to fix and arrange. Alternatively, the electrode member 17 integrated with the pressure transmission ring 15 may be formed by directly forming a highly conductive metal film on the end face of the pressure transmission ring 15. In other words, the end surface on the back side of the pressure transmission ring 15 becomes a conductive electrode surface by providing the electrode member 17.

  Next, the through hole formed in the rear housing 13 will be described with reference to FIG. In FIG. 4, a through hole 13 c that penetrates the rear housing 13 along the center line direction is formed at a predetermined position of the rear housing 13. The front side of the through hole 13c is connected to the internal space 10b that accommodates the pressure transmission ring 15 and the piezoelectric element group 16 described above, and the back side of the through hole 13c is connected to a notch 31c (described later) of the electrode connector 31. ing. The through hole 13c has a function of positioning the connection terminal 52 while inserting the connection terminal 52, exposing the connection terminal 52 from the internal space 10b to the electrode connector 31 side.

  Next, the connection terminal 52 will be described with reference to FIG. The connection terminal 52 is composed of a metal rod-like body having heat resistance and conductivity, and has a butting portion 52a that abuts against the electrode member 17 provided on the end surface of the pressure transmission ring 15, and a back side of the butting portion 52a. A stop portion 52b having a diameter larger than that of the abutting portion 52a and a connection portion 52c including a tip portion located further on the back side are integrally formed. The shape of the connection terminal 52 is not particularly limited.

  The connection terminal 52 is inserted into the through hole 13 c of the rear housing 13 from the inner space 10 b side, and the connection portion 52 c is exposed to the electrode connector 31 side adjacent to the rear housing 13. The tip of the connection portion 52c exposed to the electrode connector 31 side is laser welded to an extension electrode 32b described later, but detailed description thereof is omitted here.

  When the connection portion 52c of the connection terminal 52 is inserted into the through hole 13c, the connection portion 52 is inserted into the positioning tube 55 and positioned inside the through hole 13c. In addition, a coil spring 56 that is wound around the outer peripheral surface of the abutting portion 52 a of the connection terminal 52 and contacts the electrode member 17 to electrically connect the electrode member 17 and the connection terminal 52 is disposed. Due to the spring force of the coil spring 56, the end on the front side of the coil spring 56 contacts the electrode member 17, and the end on the back side of the coil spring 56 contacts the stop 52 b of the connection terminal 52. Thereby, even if the positional relationship between the pressure transmission ring 15 to which the electrode member 17 is fixed and the connection terminal 52 fluctuates due to external pressure, the electrode member 17 and the connection terminal 52 are reliably connected via the coil spring 56. Electrically connected.

  Further, in the vicinity of the outlet of the through-hole 13 c, an O-ring 57 is fitted into the connection portion 52 c of the connection terminal 52 in order to keep waterproof and dustproof at the time of manufacture. The O-ring 57 can prevent moisture and the like from entering the internal space 10b from the outside.

  Next, the connection electrode 32 and the electrode connector 31 as the electrical transmission means that are the features of the first embodiment will be described with reference to FIGS. 2, 5, and 6. FIG. 6 is a perspective view of a single connection electrode 32 removed from the electrode connector 31. 2, 5, and 6, the cylindrical electrode connector 31 is attached to the rear side of the rear housing 13, and the outer diameter thereof is set to be substantially the same as the outer diameter of the rear stage portion 133 of the rear housing 13. The inner diameter is set slightly larger than the inner diameter of the rear stage portion 133 of the rear housing 13 (see FIG. 2).

  The electrode connector 31 is divided into a front surface portion 31a on the front surface side and a back surface portion 31b on the back surface side, and the outer diameter of the back surface portion 31b is set slightly smaller than the outer diameter of the front surface portion 31a (FIG. 2, FIG. (See FIG. 5). The electrode connector 31 is integrated by a fitting structure (not shown) of the front surface portion 31a and the back surface portion 31b after the annular connection electrode 32 is inserted into the back surface portion 31b.

  Further, a notch 31c is formed in a part of the outer periphery of the front surface portion 31a of the electrode connector 31, and the tip of the connecting portion 52c of the connecting terminal 52 inserted into the through hole 13c is formed by the notch 31c. Is exposed to the outside.

  Thus, the connection electrode 32 is fitted into the electrode connector 31, and the electrode connector 31 is attached to the back side of the rear housing 13, that is, the back side of the housing 20. In this attached state, the connection electrode 32 fitted in the electrode connector 31 has an annular electrode surface 32 a orthogonal to the center line of the housing 20, and the electrode surface 32 a It is exposed at the end face of the back surface portion 31b (see FIG. 5).

  The connection electrode 32 has an elongated extension electrode 32b extending from a predetermined location on the electrode surface 32a toward the front surface side. Claw portions 32c to 32e are formed at a plurality of locations on the outer periphery of the electrode surface 32a of the connection electrode 32 (see FIG. 6).

  Here, the annular electrode surface 32a, as will be described in detail later, is a portion that is electrically connected to the electrode on the external device side by soldering. The extension electrode 32b is electrically connected at its distal end to the connection portion 52c of the connection terminal 52 by laser welding. Further, the plurality of claw portions 32 c to 32 e are fitted into the back surface portion 31 b of the electrode connector 31. Thereby, the connection electrode 32 can be reliably fixed to the electrode connector 31 (housing 20 side) (see FIGS. 5 and 6). For example, the connection electrode 32 is preferably a conductive member obtained by plating phosphor bronze.

  Next, the connector housing 33 that covers the electrode connector 31 from the outside will be described. In FIG. 2, the connector housing 33 has a cylindrical shape, and is composed of a front surface portion 33a on the front surface side and a back surface portion 33b on the back surface side. The outer diameter of the back surface portion 33b is larger than the outer diameter of the front surface portion 33a. Slightly smaller and integrated. Here, the inner diameter of the front surface portion 33 a of the connector housing 33 is set to be substantially the same as the outer diameter of the rear stage portion 133 of the rear housing 13 and the outer diameter of the front surface portion 31 a of the electrode connector 31. Further, the inner diameter of the back surface portion 33 b of the connector housing 33 is set to be substantially the same as the outer diameter of the back surface portion 31 b of the electrode connector 31.

  Next, the piezoelectric element group 16 incorporated in the pressure detection device 10 will be described with reference to FIGS. 2, 3, and 7. FIG. 7 is a cross-sectional view of the vicinity of the piezoelectric element group 16 cut along the cutting line FF ′ in FIG. 2, 3, and 7, the piezoelectric element group 16 includes a cylindrical rear housing 13 in an internal space 10 b between the back surface of the pressure transmission ring 15 and the front surface of the rear housing 13. A plurality of elements are arranged along the circumferential direction, supported by the rear housing 13.

  The outer side of the piezoelectric element group 16 is covered with a front outer casing 11, and the inner side is covered with a front inner casing 12. In the present embodiment, the six piezoelectric elements 161 to 166 are arranged at substantially equal intervals, but the number of the piezoelectric element groups 16 may be less than six or more.

  Here, the piezoelectric elements 161 to 166 have a common configuration, and each of them has a piezoelectric body 16a processed into a rectangular parallelepiped shape, a front-side electrode 16b formed on the front end face of the piezoelectric body 16a, and a piezoelectric element. A rear-side electrode 16c formed on an end surface on the back side of the body 16a (see FIG. 3). The front-side electrode 16b and the rear-side electrode 16c are formed such that a highly conductive metal film is opposed to the piezoelectric body 16a.

  The piezoelectric body 16a can be exemplified by using a langasite crystal (a langasite, a langagate, a langanite, LGTA) having a piezoelectric longitudinal effect and a piezoelectric transverse effect, quartz, gallium phosphate, or the like. In the piezoelectric element group 16 of the present embodiment, a langasite single crystal is used as a piezoelectric body.

  In each of the piezoelectric elements 161 to 166, each front-side electrode 16 b abuts on an electrode member 17 provided on the end face of the pressure transmission ring 15, and each rear-side electrode 16 c is a ground electrode provided on the rear housing 13. It abuts on the layer 13b (see FIG. 3).

  Spacers 171 to 176 are arranged in the circumferential gaps of the piezoelectric elements 161 to 166, and the piezoelectric elements 161 to 166 function so as to be arranged at substantially equal intervals (see FIG. 7). In addition, a spacer through hole 171 a for penetrating the connection terminal 52 is provided in a substantially central portion of the spacer 171, and the connection terminal 52 passes therethrough. The material of the spacers 171 to 176 is ceramic (alumina, zirconia) or the like, but the material is not limited as long as it is an insulating material. As described above, since the plurality of piezoelectric element groups 16 are arranged at equal intervals along the circumferential direction inside the housing 20, the pressure from the outside can be uniformly received in a balanced manner, and highly accurate pressure detection is possible. Is possible.

  Next, an outline of the assembly procedure of the pressure detection device 10 will be described with reference to FIG. In FIG. 2, as described above, the front outer casing 11, the front inner casing 12, and the rear casing 13 are assembled, and laser welding is performed on each to form an integrated casing 20. Each component (pressure transmission ring 15, piezoelectric element group 16, connection terminal 52, etc.) is incorporated inside the housing 20. Finally, the pressure receiving ring 14 is composed of the front outer housing 11 and the front inner housing 12. It is inserted into the front side of the plate and fixed by laser welding.

  Next, as described above, the electrode connector 31 is integrated with the connection electrode 32 by fitting the connection electrode 32 into the back surface portion 32b and then fitting the front surface portion 32a and the back surface portion 32b. Thereby, the tip of the extension electrode 32 b of the connection electrode 32 is exposed to the notch 31 c of the electrode connector 31.

  Next, the electrode connector 31 is attached in a predetermined direction to the rear surface side (rear stage portion 133) of the rear housing 13 of the integrated housing 20. That is, the electrode connector is located at a position where the connection portion 52c of the connection terminal 52 exposed from the through hole 13c of the rear housing 13 and the tip of the extension electrode 32b exposed to the notch portion 31c of the electrode connector 31 are in contact. 31 is attached.

  Since the contact position between the connection portion 52c of the connection terminal 52 and the extension electrode 32b of the connection electrode 32 is exposed to the outside by the cutout portion 31c of the electrode connector 31, laser irradiation is performed from above the cutout portion 31c. In step (not shown), the connection portion 52 of the connection terminal 52 and the extension electrode 32b of the connection electrode 32 are electrically connected by laser welding.

  Next, the front portion 33a of the connector housing 33 is inserted from the back side of the electrode connector 31, and further, the front end portion 33a is inserted into the middle step portion 132 of the rear case 13 of the case 20 with the front end integrated. After that, the entire circumference of the middle step 132 of the rear housing 13 and the front end 33a of the connector housing 33 are fixed by laser welding (welding point: G1). Thereby, the housing 20 and the connector housing 33 are securely coupled, and the electrode connector 31 is covered with the connector housing 33 and fixed to the housing 20. Thereby, the integrated pressure detection apparatus 10 is completed.

  The electrode surface 32a of the connection electrode 32 is exposed to the outside from the connector housing 33, and since the connection electrode 32 is incorporated in the insulating electrode connector 31, the connection electrode 32 and the connector housing 33 are It is electrically insulated.

  Thus, since the integrated pressure detection device 10 has a cylindrical shape and has an opening 10a therein, the tip 7b of the fuel injection device 7 can be disposed in the opening 10a, and the fuel The injection device 7 and the pressure detection device 10 can be incorporated into the cylinder block 2 as one injector unit 6 (see FIG. 1). Thereby, it is not necessary to provide a new communication hole in the cylinder block 2 for the pressure detection device 10, and a pressure detection device excellent in space efficiency can be provided.

  Next, the electrical connection structure of the pressure detection device according to the first embodiment will be described with reference to FIGS. 2 to 4 and FIG. 7. First, each rear electrode 16c provided on the back side of the piezoelectric elements 161 to 166 constituting the piezoelectric element group 16 is in contact with the ground electrode layer 13b provided in the rear casing 13 as described above. Electrically connected. Here, since the rear casing 13 is conductive, the rear casing 13 and the ground electrode layer 13b are in an electrically connected state (see FIG. 3).

  Here, when the injector unit 6 composed of the fuel injection device 7 and the pressure detection device 10 is attached to the cylinder head 4 shown in FIG. 1, at least the front outer casing 11 is electrically connected to the metal cylinder head 4. Connected. Since this cylinder head 4 is connected to the cylinder 2 a and is electrically grounded, the rear side electrodes 16 c of the piezoelectric elements 161 to 166 of the pressure detection device 10 are connected to the rear casing 13 and the front outer casing 11. Is connected to the ground electrode of the injector unit 6 through the ground. As a result, the rear side electrode 16c, which is one electrode of the piezoelectric element group 16, is connected to the ground electrode of the entire engine 1, so that the influence of electrical noise from the outside is cut off and highly accurate pressure detection is performed. Can be realized.

  On the other hand, each front side electrode 16b provided on the front side of the piezoelectric elements 161 to 166 constituting the piezoelectric element group 16 is in contact with the electrode member 17 provided on the end face of the pressure transmission ring 15 to be electrically connected. Connected to. With such a configuration, the piezoelectric element group 16 is sandwiched between the ground electrode layer 13 b of the rear housing 13 and the electrode member 17 and is electrically connected.

  That is, the individual piezoelectric elements 161 to 166 of the piezoelectric element group 16 are connected in parallel between the ground electrode layer 13 b and the electrode member 17. For this reason, each electric charge generated by the pressure received by each of the piezoelectric elements 161 to 166 is averaged by parallel connection and output as one electric signal, so that there is a slight difference in the position of the piezoelectric elements 161 to 166. The pressure difference due to, the characteristic variation of each piezoelectric element, etc. are canceled by averaging, and high-precision pressure detection can be realized.

  Further, since the pressure transmission ring 15 has an insulating property as described above, the pressure transmission ring 15 and the electrode member 17 are fixed, but are electrically insulated. Is also insulated from the surrounding front outer casing 11 and front inner casing 12.

  On the other hand, the electrode member 17 is electrically connected to the connection terminal 52 via the coil spring 56 (see FIG. 4). Further, as described above, in the connection terminal 52, the connection part 52c is exposed to the notch 31c of the electrode connector 31 through the through hole 13c, and the connection part 52c and the extension electrode 32b of the connection electrode 32 are electrically connected by laser welding. Connected. That is, the electrode member 17 that functions as an output electrode in contact with the front side electrode 16 b of the piezoelectric element group 16 is electrically connected to the connection electrode 32 via the connection terminal 52.

  As a result, the electrical signal from the piezoelectric element group 16 is transmitted to the connection electrode 32. As will be described later, the electrical signal can be transmitted to the external device by connecting the connection electrode 32 to the electrode on the fuel injection device 7 side. it can.

  Further, the transmission path of the electrical signal from the connection terminal 52 to the connection electrode 32 is made of metal and electrically connected to each other by the internal space 10b, the positioning tube 55, and the electrode connector 31 each made of an insulator. The front outer casing 11, the front inner casing 12, the rear casing 13, and the connector housing 33 are electrically insulated. Further, since the position of the connection terminal 52 is regulated by the through hole 13 c and the positioning tube 55, the connection terminal 52 contacts the outer peripheral surface of the front outer casing 11 and the inner peripheral surface of the front inner casing 12. No (see FIG. 4).

  In this way, the electrical connection of the pressure detection device 10 is such that a connection route is formed for each of the front side electrode 16b and the rear side electrode 16c of the piezoelectric element group 16, the rear side electrode 16c is grounded, and the front side electrode 16b is grounded. An electrical signal is transmitted from the side electrode 16b to an external device.

  Next, an example of mounting the tip 7b (see FIG. 1) of the fuel injection device 7 as an example of the pressure detection device 10 as an engine functional member to the outer periphery will be described with reference to FIG. FIG. 8 shows that the tip 7 b of the fuel injection device 7 is incorporated in the opening 10 a of the pressure detection device 10. In FIG. 8, the distal end portion 7 b of the fuel injection device 7 has a double structure of an inner casing 71 made of a substantially cylindrical metal and a substantially cylindrical outer casing 72 that covers the outer side of the inner casing 71. ing.

  The internal housing 71 is inserted into the opening 10 a of the pressure detection device 10, and the nozzle 7 c provided at the tip of the internal housing 71 is exposed from the front side of the pressure detection device 10. With this structure, the nozzle 7 c at the tip 7 b of the fuel injection device 7 can inject fuel into the combustion chamber C from the opening 10 a on the front side of the pressure detection device 10.

  On the other hand, the outer casing 72 is fitted to the stepped portion 33c at the boundary between the front surface portion 33a and the rear surface portion 33b of the connector housing 33 of the pressure detecting device 10, and laser welding is performed on the entire circumference of the stepped portion 33c. (Welding location: G2), the connector housing 33 and the external housing 72 are fixed, and the pressure detection device 10 and the fuel injection device 7 are integrated.

  In addition, cylindrical insulating members 73 and 74 having a double structure are provided in the gap between the inner casing 71 and the outer casing 72, and a cylinder that is an electrode on the external device side is provided in the gap between the insulating members 73 and 74. A shaped external electrode 75 is formed. With this structure, the external electrode 75 is sandwiched between the double-layer insulating members 73 and 74 so that it does not contact either the inner casing 71 or the outer casing 72 and is electrically insulated. ing.

  Further, the tip portion of the external electrode 75 has, for example, a three-dimensional uneven step on the entire circumference, and when the pressure detection device 10 is incorporated in the fuel injection device 7, the pressure is close to the tip portion of the external electrode 75. The electrode surface 32 a of the annular connection electrode 32 of the detection device 10 is set to be positioned. Here, after arranging the thread solder as an example around the entire circumference of the recess 75a at the tip of the external electrode 75, the thread solder is melted by incorporating the pressure detection device 10 and heating it at a predetermined temperature for a certain period of time. The electrode surface 32 a of the connection electrode 32 of the pressure detection device 10 and the external electrode 75 on the fuel injection device 7 side are electrically connected by solder 76.

  As a result, the pressure detection device 10 is attached to the fuel injection device 7, and an electric signal from the piezoelectric element group 16 incorporated in the pressure detection device 10 can be transmitted to the external electrode 75. Further, since the connection electrode 32 of the pressure detection device 10 is formed in an annular shape, it can be connected to the entire circumference of the cylindrical external electrode 75 of the fuel injection device 7 by solder 76. As described above, the connection electrode 32 is provided with the electrode surface 32a orthogonal to the center line of the housing 11, and the external electrode of the external device is electrically connected to the electrode surface 32a. The electrode surface 32a can be provided in parallel to the end surface on the side. As a result, the electrode dimensions in the center line direction can be further reduced while ensuring a wide electrode area, thereby contributing to a reduction in size of the pressure detection device 10. Moreover, since the electrode surface 32a of the connection electrode 32 is electrically connected to the cylindrical external electrode of the external device by soldering, the entire circumference of the annular connection electrode 32 can be soldered to the external electrode. It becomes. As a result, a large electrical connection area can be secured, resistance to vibration and impact, and the resistance value of the connection is small, so that a low-level electrical signal can be reliably transmitted to an external device. Moreover, the mounting direction of the pressure detection device is not limited, and the device can be easily assembled.

  Further, since the connection portion between the annular connection electrode 32 and the cylindrical external electrode 75 of the pressure detection device 10 extends over the entire circumference, the mounting direction of the pressure detection device 10 and the fuel injection device 7 (the mounting angle in the circumferential direction). ) Is not limited, and the pressure detection device 10 may be attached to the fuel injection device 7 in any direction. Thereby, an assembly of an apparatus can be performed easily. In addition, the shape of the external electrode 75 on the fuel injection device 7 side with respect to the annular connection electrode 32 is not limited to a cylindrical shape, but an arc shape having a predetermined width with respect to the connection electrode 32 or a band shape, or the like The electrode shape may be sufficient. In other words, the external electrode 75 may not be connected over the entire circumference of the annular connection electrode 32, and a part of the connection electrode 32 in the circumferential direction may be connected to the external electrode 75.

  In this case, although the electrical connection area of the connection electrode 32 and the external electrode 75 becomes narrow, since the connection electrode 32 has an annular shape, the mounting direction of the pressure detection device 10 and the fuel injection device 7 (circumferential mounting angle). The effect of not being limited is the same as that of the cylindrical external electrode 75. Further, the fact that the external electrode 75 is not limited to a cylindrical shape is the same in the second and third embodiments described later. The external electrode 75 is not directly connected to the fuel injection device 7 but will be described in detail later, but after passing through an amplifier circuit as an external device that converts an electrical signal of the pressure detection device 10, the fuel injection device 7. Or connected to other devices.

  Next, an outline of the pressure detection operation of the pressure detection device 10 attached to the engine 1 will be described with reference to the block diagram of FIG. In addition, refer to FIGS. 2 to 8 for the configuration of the pressure detection device 10. In FIG. 9, the pressure detection device 10 includes a pressure receiving ring 14, a pressure transmission ring 15, a piezoelectric element group 16, a connection terminal 52, a connection electrode 32, and the like, and is covered with a housing 20 (shown by a broken line).

  On the other hand, the fluctuation of the combustion pressure (arrow D) as the internal pressure generated in the combustion chamber C in the cylinder block 2 of the engine 1 is transferred to the piezoelectric element group 16 via the pressure receiving ring 14 and the pressure transmission ring 15 of the pressure detecting device 10. Works. At this time, the vibration generated with the fluctuation of the combustion pressure D includes a frequency component of about several KHz at the maximum.

  In this example, the piezoelectric element group 16 includes piezoelectric elements 161 to 166 arranged at equal intervals along the circumferential direction of the casing (see FIG. 7), and the piezoelectric elements 161 to 166 are substantially uniform. Electric charges corresponding to fluctuations in the combustion pressure D are generated. The electric charges generated in the piezoelectric bodies 16a constituting the piezoelectric elements 161 to 166 pass through the electrode members 17 provided on the end surfaces of the pressure transmission ring 15 as electric signals P1 from the front side electrodes 16b of the piezoelectric bodies 16a. To the connection terminal 52.

  Next, the electrical signal P <b> 1 transmitted to the connection terminal 52 is transmitted to the connection electrode 32 connected to the connection terminal 52. Further, the electrical signal P1 transmitted to the connection electrode 32 is transmitted to the amplifier circuit 77 which is a part of the external device via the external electrode 75 on the external device side to which the connection electrode 32 is connected. The amplifier circuit 77 includes an integrating circuit, integrates the electric signal P1 having a differentiated waveform, converts the electric signal P1 into a pressure signal P2, and transmits the pressure signal P2 to the control circuit 78 that controls the engine 1, whereby the fuel injection device 7 And the spark plug 5 is controlled.

  Further, the rear-side electrode 16c on the back side of the piezoelectric elements 161 to 166 constituting the piezoelectric element group 16 is electrically connected to the cylinder block 2 through the housing 20 from the ground electrode layer 13b and becomes a ground electrode. As a result, the entire housing 20 and the cylinder block 2 of the pressure detecting device 10 are grounded, so that external electrical noise can be reduced.

  Since the connection electrode 32 is formed in an annular shape, it can be electrically connected to the entire circumference of the cylindrical external electrode 75 (see FIG. 8) formed in the fuel injection device 7, and as a result, the electrical connection area Therefore, it is possible to provide a highly reliable pressure detecting device that is free from breakage or disconnection even when subjected to vibration or impact over a long period of time from the engine 1. As described above, the pressure detection device of the present invention has an excellent effect that it can be easily mounted on the outer periphery of the distal end portion of the fuel injection device 7 that is a functional member, provided with electrical transmission means that is resistant to vibration and impact. Yes.

Second embodiment

  Next, the structure of the pressure detection apparatus of 2nd Embodiment is demonstrated using FIG. In addition, FIG. 10 is sectional drawing along the centerline of the pressure detection apparatus of 2nd Embodiment. Here, the pressure detection device of the second embodiment has a configuration in which the connection electrode has a cylindrical press-fit electrode surface, and the basic configuration is the same as that of the first embodiment, and therefore the same number is assigned to the same element. A part of the overlapping explanation is omitted.

  In FIG. 10, reference numeral 80 denotes a pressure detection device according to the second embodiment. Similar to the pressure detection device 10 of the first embodiment, the pressure detection device 80 includes a front outer casing 11 having a cylindrical shape, a cylindrical shape, and inside the front outer casing 11. A front inner housing 12 arranged concentrically with the front outer housing 11, a rear housing 13 having a cylindrical shape and attached to the back side of the front outer housing 11 and the front inner housing 12, A pressure receiving ring 14 that has an annular shape and is attached to the front side of the front outer casing 11 and the front inner casing 12 and receives pressure from the outside.

  Further, the pressure transmission ring 15 that transmits the pressure from the pressure receiving ring 14 to the back surface side, and the back surface side of the pressure transmission ring 15 and the end surface on the front surface side of the rear housing 13 are received from the pressure transmission ring 15. And a piezoelectric element group 16 for converting the pressure into an electrical signal. Since the configuration and function of each of these elements are the same as in the first embodiment, detailed description thereof is omitted.

  Next, a connection electrode and an electrode connector as electrical transmission means, which is a feature of the second embodiment, will be described with reference to FIGS. FIG. 11 is a perspective view showing a state in which the connection electrode of the second embodiment is removed from the electrode connector. 10 and 11, the electrode connector 81 is attached to the rear side of the rear housing 13, and the outer diameter thereof is set to be substantially the same as the outer diameter of the rear stage portion 133 of the rear housing 13, and the inner diameter is the rear housing. The inner diameter of the rear stage 133 of the body 13 is set slightly larger.

  The electrode connector 81 is divided into a front surface portion 81a on the front surface side and a back surface portion 81b on the back surface side, and the outer diameter of the back surface portion 81b is set slightly smaller than the outer diameter of the front surface portion 81a. The electrode connector 81 is integrated by a fitting structure (not shown) of the front surface portion 81a and the back surface portion 81b after the annular connection electrode 82 is inserted into the back surface portion 81b.

  Further, a notch 81c is formed in a part of the outer periphery of the front surface portion 81a of the electrode connector 81, and the tip of the connecting portion 52c of the connecting terminal 52 inserted into the through hole 13c by the notch 81c. Part is exposed to the outside.

  The connection electrode 82 has a cylindrical press-fit electrode surface 82 a on the inner surface, and the press-fit electrode surface 82 a is positioned inside the electrode connector 81 by the connection electrode 82 being fitted into the electrode connector 81. Moreover, it has the elongate extension electrode 82b extended toward the front side from the predetermined location of the connection electrode 82. As shown in FIG.

  As in the first embodiment, the extension electrode 82b is electrically connected at its distal end to the connection portion 52c of the connection terminal 52 by laser welding. For example, the connection electrode 82 is preferably a conductive member obtained by plating phosphor bronze.

  Here, as in the first embodiment, when the tip 7b of the fuel injection device 7 is inserted into the opening 10a of the pressure detection device 10 (see FIG. 8), the press-fit electrode surface 82a of the connection electrode 82 is opened. Since it is exposed to the entire inner periphery of the portion 10a, it contacts the tip 7b of the fuel injection device 7 inserted into the opening 10a. At this time, although not shown, the shape of the external electrode on the fuel injection device 7 side is formed as an annular electrode surface that is in contact with the press-fit electrode surface 82a over the entire circumference, and the inner diameter of the press-fit electrode surface 82a and the fuel The outer diameter of the external electrode on the injection device 7 side is made substantially the same, and the external electrode surface on the fuel injection device 7 side is set to fit into the press-fit electrode surface 82a by press-fitting.

  The connector housing 33 having a cylindrical shape and covering the electrode connector 81 from the outside has the same configuration and function as the connector housing 33 of the first embodiment. The electrode connector 81 is fixed and integrated.

  With the above structure, the pressure detection device 80 of the second embodiment transmits an electrical signal from the piezoelectric element group 16 to the connection electrode 82 via the connection terminal 52, and is further electrically connected by press-fitting. Can be transmitted to the external electrode on the side. As described above, since the connection electrode 82 and the external electrode are connected by press-fitting, a process such as a soldering operation is not required, and an assembly operation for mounting the pressure detection device 80 on the fuel injection device 7 can be easily performed. it can.

  Further, since the press-fit electrode surface 82a of the connection electrode 82 is cylindrical, it can be brought into contact with the electrode surface on the fuel injection device 7 side by press-fitting around the entire circumference. As a result, a large electrical connection area with the electrode surface on the fuel injection device 7 side can be ensured, the connection is reliable, it is resistant to vibration and impact, the resistance value of the connection is reduced, and a small level electric signal is generated. Can communicate reliably. Furthermore, since the connection portion between the annular connection electrode 82 and the external electrode of the pressure detection device 80 extends over the entire circumference of the connection electrode 82, the mounting direction of the pressure detection device 80 and the fuel injection device 7 is not limited, and pressure detection is performed. The device 80 may be mounted in any direction with respect to the fuel injection device 7. Thereby, the assembly work of an apparatus can be performed easily.

Third embodiment

  Next, the structure of the pressure detection apparatus of 3rd Embodiment is demonstrated using FIG. FIG. 12 is a cross-sectional view taken along the center line of the pressure detection device of the third embodiment. Here, the pressure detection device of the third embodiment is configured to have a plurality of elastic electrodes in which connection electrodes are arranged in a ring shape. Accordingly, since the basic configuration is the same as that of the first embodiment, the same elements are denoted by the same reference numerals, and a part of overlapping description is omitted.

  In FIG. 12, reference numeral 90 denotes the pressure detection device of the third embodiment. Similar to the pressure detection device 10 of the first embodiment, the pressure detection device 90 includes a front outer casing 11 having a cylindrical shape, a cylindrical shape, and inside the front outer casing 11. A front inner housing 12 arranged concentrically with the front outer housing 11, a rear housing 13 having a cylindrical shape and attached to the back side of the front outer housing 11 and the front inner housing 12, A pressure receiving ring 14 that has an annular shape and is attached to the front side of the front outer casing 11 and the front inner casing 12 and receives pressure from the outside.

  Further, the pressure transmission ring 15 that transmits the pressure from the pressure receiving ring 14 to the back surface side, and the back surface side of the pressure transmission ring 15 and the end surface on the front surface side of the rear housing 13 are received from the pressure transmission ring 15. And a piezoelectric element group 16 for converting the pressure into an electric signal. Since the configuration and function of each of these elements are the same as in the first embodiment, detailed description thereof is omitted.

  Next, a connection electrode and an electrode connector as electrical transmission means, which is a feature of the third embodiment, will be described with reference to FIGS. FIG. 13 is a rear view of a single connection electrode when the connection electrode of the third embodiment is viewed from the back side of the pressure detection device 90. 12 and 13, the electrode connector 91 is attached to the rear side of the rear casing 13, and the outer diameter thereof is set to be substantially the same as the outer diameter of the rear stage portion 133 of the rear casing 13, and the inner diameter is the rear casing. The inner diameter of the rear stage 133 of the body 13 is set slightly larger.

  The electrode connector 91 is divided into a front surface portion 91a on the front surface side and a back surface portion 91b on the back surface side, and the outer diameter of the back surface portion 91b is set slightly smaller than the outer diameter of the front surface portion 91a. The electrode connector 91 is integrated by a fitting structure (not shown) of the front surface portion 91a and the back surface portion 91b after the annular connection electrode 92 is inserted into the back surface portion 91b.

  Further, a notch 91c is formed in a part of the outer periphery of the front surface portion 91a of the electrode connector 91, and the tip of the connecting portion 52c of the connecting terminal 52 inserted into the through hole 13c is formed by the notch 91c. Part is exposed to the outside.

  The connection electrode 92 has a plurality of holding springs 92a as elastic electrodes arranged in an annular shape along the entire inner periphery, and the holding springs 92a are inserted into the electrode connector 91, It is located all around the inside of the electrode connector 91. Moreover, it has the elongate extension electrode 92b extended toward the front side from the predetermined location of the connection electrode 92. As shown in FIG.

  As in the first embodiment, the extension electrode 92b is electrically connected at its distal end to the connection portion 52c of the connection terminal 52 by laser welding. For example, the connecting electrode 92 is preferably a conductive member obtained by plating phosphor bronze.

  Here, as in the first embodiment, when the tip 7b of the fuel injection device 7 is inserted into the opening 10a of the pressure detection device 90 (see FIG. 8), the holding spring 92a of the connection electrode 92 is opened. Since it is exposed to the entire inner periphery of the portion 10a, it contacts the tip 7b of the fuel injection device 7 inserted into the opening 10a. At this time, although not illustrated, the shape of the external electrode on the fuel injection device 7 side is formed as an annular electrode surface that contacts the pressing spring 92a over the entire circumference, and the outer diameter of the electrode surface is the pressing spring. The diameter 92a is set to a diameter that contacts the entire circumference of the external electrode and bends by a predetermined amount. Thereby, when the tip 7b of the fuel injection device 7 is inserted into the opening 10a of the pressure detection device 90, all the pressing springs 92a exposed to the entire inner periphery of the opening 10a are moved to the fuel injection device 7. The external electrode on the side is contacted with a predetermined spring pressure, and the external electrode on the pressure detection device 90 and the fuel injection device 7 side is electrically connected.

  The connector housing 33 having a cylindrical shape and covering the electrode connector 91 from the outside has the same configuration and function as the connector housing 33 of the first embodiment. The electrode connector 91 is fixed and integrated.

  With the above structure, the pressure detection device 90 according to the third embodiment transmits an electrical signal from the piezoelectric element group 16 to the connection electrode 92 via the connection terminal 52, and further, the electrical pressure is detected by the plurality of holding springs 92 a of the connection electrode 92. Can be transmitted to the external electrode on the side of the fuel injection device 7 to be connected. Thus, since the connection electrode 92 and the external electrode are connected by the spring pressure of the holding spring 92a, a process such as a soldering operation is not required, and an assembly operation for mounting the pressure detection device 90 on the fuel injection device 7 is performed. It can be done easily.

  Furthermore, since a plurality of holding springs 92 a are arranged in an annular shape along the entire inner periphery of the connection electrode 92, the presser spring 92 a contacts the electrode surface on the fuel injection device 7 side on the entire periphery of the connection electrode 92. As a result, a large electrical connection area with the electrode surface on the fuel injection device 7 side can be ensured, the connection is reliable, it is resistant to vibration and impact, the resistance value of the connection is reduced, and a small level electric signal is generated. Can communicate reliably.

  Further, since the connection portion between the annular connection electrode 92 and the external electrode of the pressure detection device 90 extends over the entire circumference of the connection electrode 92, the mounting direction of the pressure detection device 90 and the fuel injection device 7 is not limited, and pressure detection is performed. The device 90 may be attached in any direction with respect to the fuel injection device 7. Thereby, the assembly work of an apparatus can be performed easily. In the present embodiment, the electrode spring on the side of the external device is brought into contact with the deflection of the holding spring 92a. Therefore, even if there is some variation in the size of the connection electrode 92 and the size of the external electrode, the contact state is less affected. There is. Note that the number of the presser springs 92a formed on the entire circumference of the connection electrode 92 is not particularly limited as long as it is arranged in an annular shape.

  Further, in the present embodiment, the plurality of pressing springs 92a of the connection electrode 92 are annularly arranged along the entire inner periphery of the connection electrode 92, but the position of the pressing spring 92a is not limited to this. For example, although not shown, the connection electrode 92 is configured as an electrode surface (see the electrode surface 32a in FIG. 6) perpendicular to the center line of the housing, as in the first embodiment, and a plurality of pressing members are formed on the electrode surface. You may form so that a spring may be cyclic | annular and a presser spring may bend in the centerline direction of a housing | casing. The external electrode on the fuel injection device 7 side may be formed as an annular electrode surface orthogonal to the center line corresponding to the position of the holding spring.

  With this structure, when the distal end portion 7b of the fuel injection device 7 is inserted into the opening 10a of the pressure detection device 90, a plurality of holding springs formed in an annular shape on the electrode surface orthogonal to the center line of the casing are on the fuel injection device 7 side. Therefore, a pressure detecting device having the same effect as that of the second embodiment can be realized.

  Although various embodiments have been described in detail above, the present invention is not limited to such embodiments, and the detailed configuration, shape, material, quantity, and the like are within the scope that does not depart from the spirit of the present invention. , Can be changed, added and deleted arbitrarily. Further, the functional member to which the pressure detection device of the present invention is attached is not limited to the fuel injection device, and any device incorporated in the engine can be applied.

  The pressure detection device according to the present invention can be used when measuring the pressure in the combustion chamber of the engine, particularly when detecting the combustion pressure by attaching it to the outer periphery of the tip of a spark plug, an injector or the like.

Claims (11)

In a pressure detection device configured in a cylindrical shape that detects the internal pressure of a cylinder by being mounted on the outer periphery of the tip of a functional member facing the combustion chamber of the engine,
A pressure receiving member that receives pressure from the outside, a pressure transmission member that transmits pressure from the pressure receiving member, a piezoelectric element that contacts the pressure transmission member to detect pressure fluctuations, and an electrode member that contacts the piezoelectric element And
The piezoelectric element outputs an electrical signal corresponding to pressure from two opposing electrodes,
One of the electrodes of the piezoelectric element becomes a ground electrode by abutting on a housing supporting the piezoelectric element,
The other electrode contacts the electrode member provided between the pressure transmission member and the piezoelectric element,
The electrode member is electrically connected to the electrical transmission means via a connection terminal,
The electrical transmission means includes an annular connection electrode, and transmits the electrical signal to an external device through the connection electrode.   2. The pressure detecting device according to claim 1, wherein one or a plurality of the piezoelectric elements are arranged along a circumferential direction inside the casing, and the piezoelectric elements are alternately arranged via a spacer.   The pressure detection device according to claim 2, wherein the connection terminal is connected to the electrical transmission means through a through hole provided in the spacer and the casing.   4. The pressure detecting device according to claim 1, wherein a spring is interposed between the connection terminal and the electrode member.   The said connection electrode has an electrode surface orthogonal to the centerline of the said housing | casing, The external electrode of the said external apparatus is electrically connected to this electrode surface, The any one of Claims 1-4 characterized by the above-mentioned. The pressure detection apparatus as described.   The connection electrode integrally has an elongated extension electrode extending from a predetermined portion of the electrode surface, and the extension electrode is electrically connected to a tip portion of the connection terminal exposed from the through hole. The pressure detection device according to claim 5.   The pressure detecting device according to claim 5 or 6, wherein the connection electrode has a claw portion formed at a plurality of locations on the outer periphery of the electrode surface, and is fixed to the housing side through the claw portion.   8. The external device has a cylindrical external electrode, and the electrode surface of the connection electrode is electrically connected to the external electrode by soldering. Pressure sensing device.   The said connection electrode has the cylindrical electrode surface accommodated in the inner surface of the opening part by the side of the said housing | casing, The external electrode of the said external apparatus is electrically connected to this electrode surface. The pressure detection device according to any one of 5.   The pressure detection device according to claim 9, wherein the electrode surface is electrically connected by press-fitting an external electrode of the external device.   The pressure according to claim 9 or 10, wherein the electrode surface has a plurality of elastic electrodes arranged in an annular shape, and the elastic electrodes are in electrical contact with the external electrodes of the external device. Detection device.

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